Anna M. McDivit, MD

A 23-year-old man presents to the emergency department with the sudden onset of palpitations, lightheadedness, and dyspnea, accompanied by weakness and nausea, which started earlier in the evening. He estimates that he has experienced 15 similar episodes, lasting minutes to hours, since the age of 16, with the last one 3 years ago. These episodes typically end by themselves or with self-induced vomiting and lying supine. The current episode did not resolve with these maneuvers.

He has never received medical attention for these symptoms. He has no chest pain, orthopnea, paroxysmal nocturnal dyspnea, lower extremity edema, or syncope. He has had no recent illness, contacts with sick people, or travel.

The patient’s history includes a “childhood heart murmur,” which resolved, and also mild asthma. He is otherwise healthy but has not received regular medical care. He used to play competitive soccer but quit because playing made his symptoms of dyspnea on exertion and palpitations much worse.

He uses marijuana frequently and alcohol occasionally. He does not smoke tobacco or use other recreational drugs. Other than infrequent use of albuterol, he does not take any prescription or over-the-counter medications. He has no allergies. He knows of no family history of arrhythmia or sudden cardiac death.

Physical examination. On initial examination, his temperature is 36.4°C (97.5°F), heart rate 230 bpm, systolic blood pressure 60 mm Hg, respiratory rate 30 breaths per minute, oxygen saturation 100% while breathing room air, and body mass index 25 kg/m².

He is awake, anxious, and appears ill. He speaks only in short sentences. A focused cardiac examination reveals a regular tachycardia with no appreciable murmur or extra heart sounds; the apical impulse is not displaced. His lungs are clear. His abdomen is soft and nontender. He has 2+ pulses on a scale of 0 to 4+, with no peripheral edema.

His initial electrocardiogram (ECG) (Figure 1) shows a heart rate of 260 bpm and a regular wide complex tachycardia, defined as a rate greater than 100 bpm and a QRS complex wider than 0.12 seconds.

FOCUS ON REGULAR WIDE COMPLEX TACHYCARDIA

1. Which of the following is not in the differential diagnosis of regular wide complex tachycardia?

• Monomorphic ventricular tachycardia
• Orthodromic atrioventricular reentrant tachycardia 
• Antidromic atrioventricular reentrant tachycardia
• Sinus tachycardia with bundle branch block

Orthodromic atrioventricular reentrant tachycardia is not in the differential diagnosis.

Wide complex tachycardia can occur when the impulse originates outside the normal conduction system or when there is abnormal ventricular activation through the atrioventricular (AV) node and His-Purkinje system.

The main distinction to make when diagnosing the cause of a wide complex tachycardia is between the following:

Monomorphic ventricular tachycardia, which originates from a single ventricular focus that depolarizes the adjacent myocardium in a stepwise fashion, causing a wide QRS complex that does not begin in the native conduction system, and

Sinus tachycardia with bundle branch block, ie, supraventricular tachycardia with aberrant conduction within the normal conduction system. 

Three different conduction patterns are seen with atrioventricular reentrant tachycardia (Figure 2):

Sinus depolarization (Figure 2), in which the atrial impulse travels down the AV node, and the accessory pathway can be hidden and not contribute to the surface ECG.

Orthodromic atrioventricular reentrant tachycardia (Figure2), in which the depolarizing impulse travels antegrade down the AV node, then propagates from the ventricle back to the atria via the accessory pathway, resulting in a narrow QRS.

Antidromic atrioventricular reentrant tachycardia (Figure 2), in which the depolarization travels antegrade down the accessory pathway then propagates from the ventricle back to the atria via the AV node, resulting in a wide complex QRS with a delta wave.

Important features of the patient’s electrocardiogram (Figure 1) are consistent with antidromic atrioventricular reentrant tachycardia:

• “Buried” retrograde P waves, which are best seen in the continuous strip of lead II as a positive deflection notching in the negative nadir of the wave
• The PR segment is short, suggesting retrograde atrial depolarization
• The P wave is followed by a slow slurred upstroke (delta wave), best seen in lead I.

Treatment depends on diagnosis

Distinguishing supraventricular tachycardia from ventricular tachycardia is important, as the treatments differ. Supraventricular tachycardia is treated with adenosine, calcium channel blockers, and beta-blockers, which are not only ineffective for ventricular tachycardia, but rarely may precipitate hemodynamic deterioration.

Also important is distinguishing pre-excitation atrial fibrillation from other types of supraventricular tachycardia with aberrancy, because the nodal blockade used to treat other causes of the condition may worsen the tachycardia via the accessory pathway. If pre-excitation atrial fibrillation is suspected on the basis of an irregular wide complex tachycardia with delta waves on ECG, then procainamide—a sodium channel blocker that affects the cardiac action potential and prolongs the refractory period of the accessory pathway—can be used to help control the arrhythmia.¹

Brugada criteria aid diagnosis

Adapted from Brugada P, et al. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation 1991; 83:1649–1659, with permission from Lippincott Williams & Wilkins.

In 1991, Brugada et al² devised an algorithm to differentiate ventricular tachycardia from supraventricular tachycardia with aberrancy in the setting of regular wide complex tachycardia (Figure 3). It has a sensitivity of 98.7% and a specificity of 96.5% for diagnosing ventricular tachycardia and 96.5% sensitivity and 98.7% specificity for diagnosing supraventricular tachycardia with aberrant conduction. Using the algorithm, only 11 (ie, 2%) of the 544 tachycardias in their study were misclassified.^2–4

The Brugada algorithm consists of four criteria, with the presence of any leading to a diagnosis of ventricular tachycardia:

• Absence of an RS complex in all precordial leads (the QRS complexes in precordial leads have all negative or all positive deflections).
• An RS interval in at least one precordial lead of at least 100 ms (the interval is measured from the onset of R to the nadir of the S wave).
• AV dissociation, as determined by the existence of P waves marching out independent of the QRS complexes, capture beats (narrow QRS complexes resulting from the rare occasion when an intrinsic P wave conducts down the native pathway), or fusion beats (combined capture beat and ventricular beat, resulting in a different morphology than most of the wide QRS complexes present).
• Leads V₁, V₂, and V₆ satisfying the classic morphologic criteria for ventricular tachycardia.

If none of these criteria are met, supraventricular tachycardia is diagnosed.

In our patient, we can further confirm the diagnosis of antidromic atrioventricular reentrant tachycardia by using Brugada criteria to exclude ventricular tachycardia (Figure 3): the ECG (Figure 1) shows an RS complex in multiple precordial leads, the maximum RS interval is less than 100 ms in the precordial leads, there is no evidence of AV dissociation (lead II in the continuous strip shows buried P waves associated with QRS), and morphologic criteria are not met for ventricular tachycardia in leads V₁, V₂, and V₆. 

IS CARDIOVERSION NEEDED?

According to the American Heart Association guidelines for advanced cardiopulmonary life support, patients with tachyarrhythmias who are hemodynamically unstable should undergo cardioversion immediately.⁵

Our patient, who has a heart rate faster than 200 bpm and a systolic blood pressure of only 60 mm Hg, undergoes synchronized cardioversion in the emergency department. Immediately afterward, his ECG (Figure 4) demonstrates sinus rhythm with pre-excitation consistent with type B Wolff-Parkinson-White syndrome.

Once he is hemodynamically stable, a more thorough physical examination is performed. Examination of the head, ears, eyes, nose, and throat is unremarkable. He has no jugular venous distention or carotid bruits. His lungs are clear to auscultation bilaterally, without wheezes. His cardiac examination shows a regular rate and rhythm, normal first and second heart sounds, and no murmurs, rubs, or gallops.

WHICH DIAGNOSTIC STUDIES ARE NEEDED?

Laboratory tests

In an otherwise healthy young patient presenting with an arrhythmia, the initial laboratory workup should focus on a precipitating illness or a disease state that may incite an arrhythmia.

Our patient is evaluated for infection or septic shock (white blood cell count with differential), anemia (hemoglobin), thyrotoxicosis (thyroid-stimulating hormone and free thyroxine levels), drug abuse (urine toxicology screen), and cardiac syndromes including structural heart disease and myocardial injury (cardiac enzymes and B-type natriuretic peptide).⁶

His initial laboratory tests show normal electrolyte levels and renal function, leukocytosis with a white blood cell count of 15.6 × 10⁹/L (normal 4.0–10.0), mildly elevated thyroid-stimulating hormone, and a negative urine toxicology screen.

Transthoracic echocardiography

For a young patient presenting with pre-excitation on ECG and hemodynamic instability, transthoracic echocardiography to evaluate chamber size and look for structural abnormalities is a reasonable option.

Our patient undergoes transthoracic echocardiography, which demonstrates normal left ventricular size and function with a left ventricular ejection fraction of 69%, moderate right atrial enlargement, and mild right ventricular enlargement (Figure 5). The septal leaflet of the tricuspid valve is apically displaced, and there is mild regurgitation.

DIAGNOSIS: EBSTEIN ANOMALY

These findings are consistent with Ebstein anomaly. It can be recognized on transthoracic echocardiography as adherence of the septal and posterior tricuspid valve leaflets to the myocardium due to failure of the tissue to detach during embryogenesis, apical displacement of the annulus, right atrial enlargement, and right ventricular enlargement.^7–10 Apical displacement of the tricuspid valve is a hallmark finding and must be more than 20 mm or 8 mm/m² of body surface area to make the diagnosis.^11–13 ECG often demonstrates right atrial enlargement, first-degree atrial ventricular block, and right bundle branch block.

Ebstein anomaly is a rare embryonic developmental abnormality of the tricuspid valve. It occurs in 1 to 5 of 200,000 live births, accounting for approximately 0.5% of all congenital heart disease.^14,15 Most cases are sporadic and result from failure of the ventricle to delaminate during embryogenesis of the tricuspid valve, resulting in apical displacement of either the septal, posterior, or, very rarely, anterior leaflet of the tricuspid valve.^7,8 The prevalence is higher in infants whose mothers took lithium during early pregnancy.¹⁶

2. Which of the following is not a common finding associated with Ebstein anomaly?

• Apical displacement of the septal leaflet of the tricuspid valve
• Wolff-Parkinson-White syndrome
• Accessory bypass tract
• Tachyarrhythmias
• Increased risk of sudden death
• Left-sided heart failure

The answer is left-sided heart failure. Ebstein anomaly is associated with increased risk of tachyarrhythmias, right-sided heart failure, and sudden death.^7,8,17,18 In Ebstein anomaly, the tricuspid valve forms closer to the apex, so the part of the right ventricle that is superior to the displaced tricuspid valve functions as the right atrium, thus the term “atrialized” right ventricle. These abnormalities create an environment for accessory pathways, most commonly type B Wolff-Parkinson-White syndrome.¹⁹ Biventricular dysfunction can occur in rare severe cases.^7,8,18

Our patient is found to have an accessory tract-mediated antidromic atrioventricular reentrant tachycardia in the setting of Wolff-Parkinson-White syndrome and Ebstein anomaly. This is further confirmed with an electrophysiology study demonstrating a right posterior accessory pathway.

TREATMENT FOR EBSTEIN ANOMALY

3. Which treatment is advised for Ebstein anomaly?

• Observation alone
• Standard heart failure medications
• Radiofrequency catheter ablation
• Tricuspid valve repair or replacement
• Biventricular reconstruction
• Heart transplant

The answer is all of the above. Observation alone is advised for patients with mild symptoms, no evidence of right-to-left shunting, and only mild cardiomegaly. Medical management includes an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, a beta-blocker, and diuretics. Radiofrequency catheter ablation is the first-line therapy for patients with symptomatic Wolff-Parkinson-White syndrome.²⁰ A patient who develops worsening right-sided heart failure, cyanosis, paradoxical emboli, or frequent tachyarrhythmias should be considered for corrective surgery, which may include tricuspid valve repair or replacement, or biventricular reconstruction.^7,8,21 Cardiac transplant is reserved for severe cases.⁸

On hospital day 4, our patient undergoes successful radiofrequency catheter ablation without complications. At follow-up 3 months later, he continues to do well, with resolution of his symptoms and no further evidence of pre-excitation. His postprocedure ECG no longer shows delta waves.

TAKE-HOME POINTS

• For a patient with regular wide complex tachycardia, the first step is to assess hemodynamic stability. If the patient is hemodynamically unstable, emergent cardioversion is indicated.
• The differential diagnosis for regular wide complex tachycardia includes supraventricular tachycardia with aberrancy (orthodromic atrioventricular reentrant tachycardia, antidromic atrioventricular reentrant tachycardia, atrial tachycardia), and ventricular tachycardia.
• When pre-excited atrial fibrillation is suspected, AV nodal blocking agents should be avoided, as they may worsen tachyarrhythmia. Sodium channel blockers such as procainamide can help slow down the conduction of the accessory pathway.
• Ebstein anomaly is diagnosed on transthoracic echocardiography as apical displacement of the tricuspid valve resulting in atrialization of the right ventricle.
• Patients with Ebstein anomaly have a higher risk of death from right-sided heart failure and tachyarrhythmias, most commonly type B Wolff-Parkinson-White syndrome.
• Ebstein anomaly is medically managed with standard heart failure medications, including neurohormonal blockade therapies.
• Patients with Ebstein anomaly and cyanosis require surgical intervention with either valve repair or replacement.
   

Acknowledgment: We thank Dr. William Collins for his contribution in reviewing the manuscript and his technical expertise in developing some of the figures.

A 23-year-old man presents to the emergency department with the sudden onset of palpitations, lightheadedness, and dyspnea, accompanied by weakness and nausea, which started earlier in the evening. He estimates that he has experienced 15 similar episodes, lasting minutes to hours, since the age of 16, with the last one 3 years ago. These episodes typically end by themselves or with self-induced vomiting and lying supine. The current episode did not resolve with these maneuvers.

He has never received medical attention for these symptoms. He has no chest pain, orthopnea, paroxysmal nocturnal dyspnea, lower extremity edema, or syncope. He has had no recent illness, contacts with sick people, or travel.

The patient’s history includes a “childhood heart murmur,” which resolved, and also mild asthma. He is otherwise healthy but has not received regular medical care. He used to play competitive soccer but quit because playing made his symptoms of dyspnea on exertion and palpitations much worse.

He uses marijuana frequently and alcohol occasionally. He does not smoke tobacco or use other recreational drugs. Other than infrequent use of albuterol, he does not take any prescription or over-the-counter medications. He has no allergies. He knows of no family history of arrhythmia or sudden cardiac death.

Physical examination. On initial examination, his temperature is 36.4°C (97.5°F), heart rate 230 bpm, systolic blood pressure 60 mm Hg, respiratory rate 30 breaths per minute, oxygen saturation 100% while breathing room air, and body mass index 25 kg/m².

He is awake, anxious, and appears ill. He speaks only in short sentences. A focused cardiac examination reveals a regular tachycardia with no appreciable murmur or extra heart sounds; the apical impulse is not displaced. His lungs are clear. His abdomen is soft and nontender. He has 2+ pulses on a scale of 0 to 4+, with no peripheral edema.

His initial electrocardiogram (ECG) (Figure 1) shows a heart rate of 260 bpm and a regular wide complex tachycardia, defined as a rate greater than 100 bpm and a QRS complex wider than 0.12 seconds.

FOCUS ON REGULAR WIDE COMPLEX TACHYCARDIA

1. Which of the following is not in the differential diagnosis of regular wide complex tachycardia?

• Monomorphic ventricular tachycardia
• Orthodromic atrioventricular reentrant tachycardia 
• Antidromic atrioventricular reentrant tachycardia
• Sinus tachycardia with bundle branch block

Orthodromic atrioventricular reentrant tachycardia is not in the differential diagnosis.

Wide complex tachycardia can occur when the impulse originates outside the normal conduction system or when there is abnormal ventricular activation through the atrioventricular (AV) node and His-Purkinje system.

The main distinction to make when diagnosing the cause of a wide complex tachycardia is between the following:

Monomorphic ventricular tachycardia, which originates from a single ventricular focus that depolarizes the adjacent myocardium in a stepwise fashion, causing a wide QRS complex that does not begin in the native conduction system, and

Sinus tachycardia with bundle branch block, ie, supraventricular tachycardia with aberrant conduction within the normal conduction system. 

Three different conduction patterns are seen with atrioventricular reentrant tachycardia (Figure 2):

Sinus depolarization (Figure 2), in which the atrial impulse travels down the AV node, and the accessory pathway can be hidden and not contribute to the surface ECG.

Orthodromic atrioventricular reentrant tachycardia (Figure2), in which the depolarizing impulse travels antegrade down the AV node, then propagates from the ventricle back to the atria via the accessory pathway, resulting in a narrow QRS.

Antidromic atrioventricular reentrant tachycardia (Figure 2), in which the depolarization travels antegrade down the accessory pathway then propagates from the ventricle back to the atria via the AV node, resulting in a wide complex QRS with a delta wave.

Important features of the patient’s electrocardiogram (Figure 1) are consistent with antidromic atrioventricular reentrant tachycardia:

• “Buried” retrograde P waves, which are best seen in the continuous strip of lead II as a positive deflection notching in the negative nadir of the wave
• The PR segment is short, suggesting retrograde atrial depolarization
• The P wave is followed by a slow slurred upstroke (delta wave), best seen in lead I.

Treatment depends on diagnosis

Distinguishing supraventricular tachycardia from ventricular tachycardia is important, as the treatments differ. Supraventricular tachycardia is treated with adenosine, calcium channel blockers, and beta-blockers, which are not only ineffective for ventricular tachycardia, but rarely may precipitate hemodynamic deterioration.

Also important is distinguishing pre-excitation atrial fibrillation from other types of supraventricular tachycardia with aberrancy, because the nodal blockade used to treat other causes of the condition may worsen the tachycardia via the accessory pathway. If pre-excitation atrial fibrillation is suspected on the basis of an irregular wide complex tachycardia with delta waves on ECG, then procainamide—a sodium channel blocker that affects the cardiac action potential and prolongs the refractory period of the accessory pathway—can be used to help control the arrhythmia.¹

Brugada criteria aid diagnosis

Adapted from Brugada P, et al. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation 1991; 83:1649–1659, with permission from Lippincott Williams & Wilkins.

In 1991, Brugada et al² devised an algorithm to differentiate ventricular tachycardia from supraventricular tachycardia with aberrancy in the setting of regular wide complex tachycardia (Figure 3). It has a sensitivity of 98.7% and a specificity of 96.5% for diagnosing ventricular tachycardia and 96.5% sensitivity and 98.7% specificity for diagnosing supraventricular tachycardia with aberrant conduction. Using the algorithm, only 11 (ie, 2%) of the 544 tachycardias in their study were misclassified.^2–4

The Brugada algorithm consists of four criteria, with the presence of any leading to a diagnosis of ventricular tachycardia:

• Absence of an RS complex in all precordial leads (the QRS complexes in precordial leads have all negative or all positive deflections).
• An RS interval in at least one precordial lead of at least 100 ms (the interval is measured from the onset of R to the nadir of the S wave).
• AV dissociation, as determined by the existence of P waves marching out independent of the QRS complexes, capture beats (narrow QRS complexes resulting from the rare occasion when an intrinsic P wave conducts down the native pathway), or fusion beats (combined capture beat and ventricular beat, resulting in a different morphology than most of the wide QRS complexes present).
• Leads V₁, V₂, and V₆ satisfying the classic morphologic criteria for ventricular tachycardia.

If none of these criteria are met, supraventricular tachycardia is diagnosed.

In our patient, we can further confirm the diagnosis of antidromic atrioventricular reentrant tachycardia by using Brugada criteria to exclude ventricular tachycardia (Figure 3): the ECG (Figure 1) shows an RS complex in multiple precordial leads, the maximum RS interval is less than 100 ms in the precordial leads, there is no evidence of AV dissociation (lead II in the continuous strip shows buried P waves associated with QRS), and morphologic criteria are not met for ventricular tachycardia in leads V₁, V₂, and V₆. 

IS CARDIOVERSION NEEDED?

According to the American Heart Association guidelines for advanced cardiopulmonary life support, patients with tachyarrhythmias who are hemodynamically unstable should undergo cardioversion immediately.⁵

Our patient, who has a heart rate faster than 200 bpm and a systolic blood pressure of only 60 mm Hg, undergoes synchronized cardioversion in the emergency department. Immediately afterward, his ECG (Figure 4) demonstrates sinus rhythm with pre-excitation consistent with type B Wolff-Parkinson-White syndrome.

Once he is hemodynamically stable, a more thorough physical examination is performed. Examination of the head, ears, eyes, nose, and throat is unremarkable. He has no jugular venous distention or carotid bruits. His lungs are clear to auscultation bilaterally, without wheezes. His cardiac examination shows a regular rate and rhythm, normal first and second heart sounds, and no murmurs, rubs, or gallops.

WHICH DIAGNOSTIC STUDIES ARE NEEDED?

Laboratory tests

In an otherwise healthy young patient presenting with an arrhythmia, the initial laboratory workup should focus on a precipitating illness or a disease state that may incite an arrhythmia.

Our patient is evaluated for infection or septic shock (white blood cell count with differential), anemia (hemoglobin), thyrotoxicosis (thyroid-stimulating hormone and free thyroxine levels), drug abuse (urine toxicology screen), and cardiac syndromes including structural heart disease and myocardial injury (cardiac enzymes and B-type natriuretic peptide).⁶

His initial laboratory tests show normal electrolyte levels and renal function, leukocytosis with a white blood cell count of 15.6 × 10⁹/L (normal 4.0–10.0), mildly elevated thyroid-stimulating hormone, and a negative urine toxicology screen.

Transthoracic echocardiography

For a young patient presenting with pre-excitation on ECG and hemodynamic instability, transthoracic echocardiography to evaluate chamber size and look for structural abnormalities is a reasonable option.

Our patient undergoes transthoracic echocardiography, which demonstrates normal left ventricular size and function with a left ventricular ejection fraction of 69%, moderate right atrial enlargement, and mild right ventricular enlargement (Figure 5). The septal leaflet of the tricuspid valve is apically displaced, and there is mild regurgitation.

DIAGNOSIS: EBSTEIN ANOMALY

These findings are consistent with Ebstein anomaly. It can be recognized on transthoracic echocardiography as adherence of the septal and posterior tricuspid valve leaflets to the myocardium due to failure of the tissue to detach during embryogenesis, apical displacement of the annulus, right atrial enlargement, and right ventricular enlargement.^7–10 Apical displacement of the tricuspid valve is a hallmark finding and must be more than 20 mm or 8 mm/m² of body surface area to make the diagnosis.^11–13 ECG often demonstrates right atrial enlargement, first-degree atrial ventricular block, and right bundle branch block.

Ebstein anomaly is a rare embryonic developmental abnormality of the tricuspid valve. It occurs in 1 to 5 of 200,000 live births, accounting for approximately 0.5% of all congenital heart disease.^14,15 Most cases are sporadic and result from failure of the ventricle to delaminate during embryogenesis of the tricuspid valve, resulting in apical displacement of either the septal, posterior, or, very rarely, anterior leaflet of the tricuspid valve.^7,8 The prevalence is higher in infants whose mothers took lithium during early pregnancy.¹⁶

2. Which of the following is not a common finding associated with Ebstein anomaly?

• Apical displacement of the septal leaflet of the tricuspid valve
• Wolff-Parkinson-White syndrome
• Accessory bypass tract
• Tachyarrhythmias
• Increased risk of sudden death
• Left-sided heart failure

The answer is left-sided heart failure. Ebstein anomaly is associated with increased risk of tachyarrhythmias, right-sided heart failure, and sudden death.^7,8,17,18 In Ebstein anomaly, the tricuspid valve forms closer to the apex, so the part of the right ventricle that is superior to the displaced tricuspid valve functions as the right atrium, thus the term “atrialized” right ventricle. These abnormalities create an environment for accessory pathways, most commonly type B Wolff-Parkinson-White syndrome.¹⁹ Biventricular dysfunction can occur in rare severe cases.^7,8,18

Our patient is found to have an accessory tract-mediated antidromic atrioventricular reentrant tachycardia in the setting of Wolff-Parkinson-White syndrome and Ebstein anomaly. This is further confirmed with an electrophysiology study demonstrating a right posterior accessory pathway.

TREATMENT FOR EBSTEIN ANOMALY

3. Which treatment is advised for Ebstein anomaly?

• Observation alone
• Standard heart failure medications
• Radiofrequency catheter ablation
• Tricuspid valve repair or replacement
• Biventricular reconstruction
• Heart transplant

The answer is all of the above. Observation alone is advised for patients with mild symptoms, no evidence of right-to-left shunting, and only mild cardiomegaly. Medical management includes an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, a beta-blocker, and diuretics. Radiofrequency catheter ablation is the first-line therapy for patients with symptomatic Wolff-Parkinson-White syndrome.²⁰ A patient who develops worsening right-sided heart failure, cyanosis, paradoxical emboli, or frequent tachyarrhythmias should be considered for corrective surgery, which may include tricuspid valve repair or replacement, or biventricular reconstruction.^7,8,21 Cardiac transplant is reserved for severe cases.⁸

On hospital day 4, our patient undergoes successful radiofrequency catheter ablation without complications. At follow-up 3 months later, he continues to do well, with resolution of his symptoms and no further evidence of pre-excitation. His postprocedure ECG no longer shows delta waves.

TAKE-HOME POINTS

• For a patient with regular wide complex tachycardia, the first step is to assess hemodynamic stability. If the patient is hemodynamically unstable, emergent cardioversion is indicated.
• The differential diagnosis for regular wide complex tachycardia includes supraventricular tachycardia with aberrancy (orthodromic atrioventricular reentrant tachycardia, antidromic atrioventricular reentrant tachycardia, atrial tachycardia), and ventricular tachycardia.
• When pre-excited atrial fibrillation is suspected, AV nodal blocking agents should be avoided, as they may worsen tachyarrhythmia. Sodium channel blockers such as procainamide can help slow down the conduction of the accessory pathway.
• Ebstein anomaly is diagnosed on transthoracic echocardiography as apical displacement of the tricuspid valve resulting in atrialization of the right ventricle.
• Patients with Ebstein anomaly have a higher risk of death from right-sided heart failure and tachyarrhythmias, most commonly type B Wolff-Parkinson-White syndrome.
• Ebstein anomaly is medically managed with standard heart failure medications, including neurohormonal blockade therapies.
• Patients with Ebstein anomaly and cyanosis require surgical intervention with either valve repair or replacement.
   

Acknowledgment: We thank Dr. William Collins for his contribution in reviewing the manuscript and his technical expertise in developing some of the figures.

A 23-year-old man presents to the emergency department with the sudden onset of palpitations, lightheadedness, and dyspnea, accompanied by weakness and nausea, which started earlier in the evening. He estimates that he has experienced 15 similar episodes, lasting minutes to hours, since the age of 16, with the last one 3 years ago. These episodes typically end by themselves or with self-induced vomiting and lying supine. The current episode did not resolve with these maneuvers.

He has never received medical attention for these symptoms. He has no chest pain, orthopnea, paroxysmal nocturnal dyspnea, lower extremity edema, or syncope. He has had no recent illness, contacts with sick people, or travel.

The patient’s history includes a “childhood heart murmur,” which resolved, and also mild asthma. He is otherwise healthy but has not received regular medical care. He used to play competitive soccer but quit because playing made his symptoms of dyspnea on exertion and palpitations much worse.

He uses marijuana frequently and alcohol occasionally. He does not smoke tobacco or use other recreational drugs. Other than infrequent use of albuterol, he does not take any prescription or over-the-counter medications. He has no allergies. He knows of no family history of arrhythmia or sudden cardiac death.

Physical examination. On initial examination, his temperature is 36.4°C (97.5°F), heart rate 230 bpm, systolic blood pressure 60 mm Hg, respiratory rate 30 breaths per minute, oxygen saturation 100% while breathing room air, and body mass index 25 kg/m².

He is awake, anxious, and appears ill. He speaks only in short sentences. A focused cardiac examination reveals a regular tachycardia with no appreciable murmur or extra heart sounds; the apical impulse is not displaced. His lungs are clear. His abdomen is soft and nontender. He has 2+ pulses on a scale of 0 to 4+, with no peripheral edema.

His initial electrocardiogram (ECG) (Figure 1) shows a heart rate of 260 bpm and a regular wide complex tachycardia, defined as a rate greater than 100 bpm and a QRS complex wider than 0.12 seconds.

FOCUS ON REGULAR WIDE COMPLEX TACHYCARDIA

1. Which of the following is not in the differential diagnosis of regular wide complex tachycardia?

• Monomorphic ventricular tachycardia
• Orthodromic atrioventricular reentrant tachycardia 
• Antidromic atrioventricular reentrant tachycardia
• Sinus tachycardia with bundle branch block

Orthodromic atrioventricular reentrant tachycardia is not in the differential diagnosis.

Wide complex tachycardia can occur when the impulse originates outside the normal conduction system or when there is abnormal ventricular activation through the atrioventricular (AV) node and His-Purkinje system.

The main distinction to make when diagnosing the cause of a wide complex tachycardia is between the following:

Monomorphic ventricular tachycardia, which originates from a single ventricular focus that depolarizes the adjacent myocardium in a stepwise fashion, causing a wide QRS complex that does not begin in the native conduction system, and

Sinus tachycardia with bundle branch block, ie, supraventricular tachycardia with aberrant conduction within the normal conduction system. 

Three different conduction patterns are seen with atrioventricular reentrant tachycardia (Figure 2):

Sinus depolarization (Figure 2), in which the atrial impulse travels down the AV node, and the accessory pathway can be hidden and not contribute to the surface ECG.

Orthodromic atrioventricular reentrant tachycardia (Figure2), in which the depolarizing impulse travels antegrade down the AV node, then propagates from the ventricle back to the atria via the accessory pathway, resulting in a narrow QRS.

Antidromic atrioventricular reentrant tachycardia (Figure 2), in which the depolarization travels antegrade down the accessory pathway then propagates from the ventricle back to the atria via the AV node, resulting in a wide complex QRS with a delta wave.

Important features of the patient’s electrocardiogram (Figure 1) are consistent with antidromic atrioventricular reentrant tachycardia:

• “Buried” retrograde P waves, which are best seen in the continuous strip of lead II as a positive deflection notching in the negative nadir of the wave
• The PR segment is short, suggesting retrograde atrial depolarization
• The P wave is followed by a slow slurred upstroke (delta wave), best seen in lead I.

Treatment depends on diagnosis

Distinguishing supraventricular tachycardia from ventricular tachycardia is important, as the treatments differ. Supraventricular tachycardia is treated with adenosine, calcium channel blockers, and beta-blockers, which are not only ineffective for ventricular tachycardia, but rarely may precipitate hemodynamic deterioration.

Also important is distinguishing pre-excitation atrial fibrillation from other types of supraventricular tachycardia with aberrancy, because the nodal blockade used to treat other causes of the condition may worsen the tachycardia via the accessory pathway. If pre-excitation atrial fibrillation is suspected on the basis of an irregular wide complex tachycardia with delta waves on ECG, then procainamide—a sodium channel blocker that affects the cardiac action potential and prolongs the refractory period of the accessory pathway—can be used to help control the arrhythmia.¹

Brugada criteria aid diagnosis

Adapted from Brugada P, et al. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation 1991; 83:1649–1659, with permission from Lippincott Williams & Wilkins.

In 1991, Brugada et al² devised an algorithm to differentiate ventricular tachycardia from supraventricular tachycardia with aberrancy in the setting of regular wide complex tachycardia (Figure 3). It has a sensitivity of 98.7% and a specificity of 96.5% for diagnosing ventricular tachycardia and 96.5% sensitivity and 98.7% specificity for diagnosing supraventricular tachycardia with aberrant conduction. Using the algorithm, only 11 (ie, 2%) of the 544 tachycardias in their study were misclassified.^2–4

The Brugada algorithm consists of four criteria, with the presence of any leading to a diagnosis of ventricular tachycardia:

• Absence of an RS complex in all precordial leads (the QRS complexes in precordial leads have all negative or all positive deflections).
• An RS interval in at least one precordial lead of at least 100 ms (the interval is measured from the onset of R to the nadir of the S wave).
• AV dissociation, as determined by the existence of P waves marching out independent of the QRS complexes, capture beats (narrow QRS complexes resulting from the rare occasion when an intrinsic P wave conducts down the native pathway), or fusion beats (combined capture beat and ventricular beat, resulting in a different morphology than most of the wide QRS complexes present).
• Leads V₁, V₂, and V₆ satisfying the classic morphologic criteria for ventricular tachycardia.

If none of these criteria are met, supraventricular tachycardia is diagnosed.

In our patient, we can further confirm the diagnosis of antidromic atrioventricular reentrant tachycardia by using Brugada criteria to exclude ventricular tachycardia (Figure 3): the ECG (Figure 1) shows an RS complex in multiple precordial leads, the maximum RS interval is less than 100 ms in the precordial leads, there is no evidence of AV dissociation (lead II in the continuous strip shows buried P waves associated with QRS), and morphologic criteria are not met for ventricular tachycardia in leads V₁, V₂, and V₆. 

IS CARDIOVERSION NEEDED?

According to the American Heart Association guidelines for advanced cardiopulmonary life support, patients with tachyarrhythmias who are hemodynamically unstable should undergo cardioversion immediately.⁵

Our patient, who has a heart rate faster than 200 bpm and a systolic blood pressure of only 60 mm Hg, undergoes synchronized cardioversion in the emergency department. Immediately afterward, his ECG (Figure 4) demonstrates sinus rhythm with pre-excitation consistent with type B Wolff-Parkinson-White syndrome.

Once he is hemodynamically stable, a more thorough physical examination is performed. Examination of the head, ears, eyes, nose, and throat is unremarkable. He has no jugular venous distention or carotid bruits. His lungs are clear to auscultation bilaterally, without wheezes. His cardiac examination shows a regular rate and rhythm, normal first and second heart sounds, and no murmurs, rubs, or gallops.

WHICH DIAGNOSTIC STUDIES ARE NEEDED?

Laboratory tests

In an otherwise healthy young patient presenting with an arrhythmia, the initial laboratory workup should focus on a precipitating illness or a disease state that may incite an arrhythmia.

Our patient is evaluated for infection or septic shock (white blood cell count with differential), anemia (hemoglobin), thyrotoxicosis (thyroid-stimulating hormone and free thyroxine levels), drug abuse (urine toxicology screen), and cardiac syndromes including structural heart disease and myocardial injury (cardiac enzymes and B-type natriuretic peptide).⁶

His initial laboratory tests show normal electrolyte levels and renal function, leukocytosis with a white blood cell count of 15.6 × 10⁹/L (normal 4.0–10.0), mildly elevated thyroid-stimulating hormone, and a negative urine toxicology screen.

Transthoracic echocardiography

For a young patient presenting with pre-excitation on ECG and hemodynamic instability, transthoracic echocardiography to evaluate chamber size and look for structural abnormalities is a reasonable option.

Our patient undergoes transthoracic echocardiography, which demonstrates normal left ventricular size and function with a left ventricular ejection fraction of 69%, moderate right atrial enlargement, and mild right ventricular enlargement (Figure 5). The septal leaflet of the tricuspid valve is apically displaced, and there is mild regurgitation.

DIAGNOSIS: EBSTEIN ANOMALY

These findings are consistent with Ebstein anomaly. It can be recognized on transthoracic echocardiography as adherence of the septal and posterior tricuspid valve leaflets to the myocardium due to failure of the tissue to detach during embryogenesis, apical displacement of the annulus, right atrial enlargement, and right ventricular enlargement.^7–10 Apical displacement of the tricuspid valve is a hallmark finding and must be more than 20 mm or 8 mm/m² of body surface area to make the diagnosis.^11–13 ECG often demonstrates right atrial enlargement, first-degree atrial ventricular block, and right bundle branch block.

Ebstein anomaly is a rare embryonic developmental abnormality of the tricuspid valve. It occurs in 1 to 5 of 200,000 live births, accounting for approximately 0.5% of all congenital heart disease.^14,15 Most cases are sporadic and result from failure of the ventricle to delaminate during embryogenesis of the tricuspid valve, resulting in apical displacement of either the septal, posterior, or, very rarely, anterior leaflet of the tricuspid valve.^7,8 The prevalence is higher in infants whose mothers took lithium during early pregnancy.¹⁶

2. Which of the following is not a common finding associated with Ebstein anomaly?

• Apical displacement of the septal leaflet of the tricuspid valve
• Wolff-Parkinson-White syndrome
• Accessory bypass tract
• Tachyarrhythmias
• Increased risk of sudden death
• Left-sided heart failure

The answer is left-sided heart failure. Ebstein anomaly is associated with increased risk of tachyarrhythmias, right-sided heart failure, and sudden death.^7,8,17,18 In Ebstein anomaly, the tricuspid valve forms closer to the apex, so the part of the right ventricle that is superior to the displaced tricuspid valve functions as the right atrium, thus the term “atrialized” right ventricle. These abnormalities create an environment for accessory pathways, most commonly type B Wolff-Parkinson-White syndrome.¹⁹ Biventricular dysfunction can occur in rare severe cases.^7,8,18

Our patient is found to have an accessory tract-mediated antidromic atrioventricular reentrant tachycardia in the setting of Wolff-Parkinson-White syndrome and Ebstein anomaly. This is further confirmed with an electrophysiology study demonstrating a right posterior accessory pathway.

TREATMENT FOR EBSTEIN ANOMALY

3. Which treatment is advised for Ebstein anomaly?

• Observation alone
• Standard heart failure medications
• Radiofrequency catheter ablation
• Tricuspid valve repair or replacement
• Biventricular reconstruction
• Heart transplant

The answer is all of the above. Observation alone is advised for patients with mild symptoms, no evidence of right-to-left shunting, and only mild cardiomegaly. Medical management includes an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, a beta-blocker, and diuretics. Radiofrequency catheter ablation is the first-line therapy for patients with symptomatic Wolff-Parkinson-White syndrome.²⁰ A patient who develops worsening right-sided heart failure, cyanosis, paradoxical emboli, or frequent tachyarrhythmias should be considered for corrective surgery, which may include tricuspid valve repair or replacement, or biventricular reconstruction.^7,8,21 Cardiac transplant is reserved for severe cases.⁸

On hospital day 4, our patient undergoes successful radiofrequency catheter ablation without complications. At follow-up 3 months later, he continues to do well, with resolution of his symptoms and no further evidence of pre-excitation. His postprocedure ECG no longer shows delta waves.

TAKE-HOME POINTS

• For a patient with regular wide complex tachycardia, the first step is to assess hemodynamic stability. If the patient is hemodynamically unstable, emergent cardioversion is indicated.
• The differential diagnosis for regular wide complex tachycardia includes supraventricular tachycardia with aberrancy (orthodromic atrioventricular reentrant tachycardia, antidromic atrioventricular reentrant tachycardia, atrial tachycardia), and ventricular tachycardia.
• When pre-excited atrial fibrillation is suspected, AV nodal blocking agents should be avoided, as they may worsen tachyarrhythmia. Sodium channel blockers such as procainamide can help slow down the conduction of the accessory pathway.
• Ebstein anomaly is diagnosed on transthoracic echocardiography as apical displacement of the tricuspid valve resulting in atrialization of the right ventricle.
• Patients with Ebstein anomaly have a higher risk of death from right-sided heart failure and tachyarrhythmias, most commonly type B Wolff-Parkinson-White syndrome.
• Ebstein anomaly is medically managed with standard heart failure medications, including neurohormonal blockade therapies.
• Patients with Ebstein anomaly and cyanosis require surgical intervention with either valve repair or replacement.
   

Acknowledgment: We thank Dr. William Collins for his contribution in reviewing the manuscript and his technical expertise in developing some of the figures.

A 61-year-old white man presents with progressive fatigue, which began several months ago and has accelerated in severity over the past week. He says he has had no shortness of breath, chest pain, or symptoms of heart failure, but he has noticed a decrease in exertional capacity and now has trouble completing his daily 5-mile walk.

He saw his primary physician, who obtained an electrocardiogram that showed a new left bundle branch block. Transthoracic echocardiography indicated that his left ventricular ejection fraction, which was 60% a year earlier, was now 35%.

He has hypertension, dyslipidemia, type 2 diabetes, and chronic kidney disease. Although he was previously morbidly obese, he has lost more than 100 pounds with diet and exercise over the past 10 years. He also used to smoke; in fact, he has a 30-pack-year history, but he quit in 1987. He has a family history of premature coronary artery disease.

Physical examination. His heart rate is 75 beats per minute, blood pressure 142/85 mm Hg, and blood oxygen saturation 96% while breathing room air. He weighs 169 pounds (76.6 kg) and he is 6 feet tall (182.9 cm), so his body mass index is 22.9 kg/m².

Electrocardiography reveals sinus rhythm with a left bundle branch block and left axis deviation (Figure 1), which were not present 1 year ago.

Chest roentgenography is normal.

A WORRISOME PICTURE

1. Which of the following is associated with left bundle branch block?

• Myocardial injury
• Hypertension
• Aortic stenosis
• Intrinsic conduction system disease
• All of the above

All of the above are true. For left bundle branch block to be diagnosed, the rhythm must be supraventricular and the QRS duration must be 120 ms or more. There should be a QS or RS complex in V₁ and a monophasic R wave in I and V₆. Also, the T wave should be deflected opposite the terminal deflection of the QRS complex. This is known as appropriate T-wave discordance with bundle branch block. A concordant T wave is nonspecific but suggests ischemia or myocardial infarction.

Potential causes of a new left bundle branch block include hypertension, acute myocardial infarction, aortic stenosis, and conduction system disease. A new left bundle branch block with a concomitant decrease in ejection fraction, especially in a patient with cardiac risk factors, is very worrisome, raising the possibility of ischemic heart disease.

MORE CARDIAC TESTING

The patient undergoes more cardiac testing.

Transthoracic echocardiography is done again. The left ventricle is normal in size, but the ejection fraction is 35%. In addition, stage 1 diastolic dysfunction (abnormal relaxation) and evidence of mechanical dyssynchrony (disruption in the normal sequence of activation and contraction of segments of the left ventricular wall) are seen. The right ventricle is normal in size and function. There is trivial mitral regurgitation and mild tricuspid regurgitation with normal right-sided pressures.

A gated rubidium-82 dipyridamole stress test yields no evidence of a fixed or reversible perfusion defect.

Left heart catheterization reveals angiographically normal coronary arteries.

Magnetic resonance imaging (MRI) shows a moderately hypertrophied left ventricle with moderately to severely depressed systolic function (left ventricular ejection fraction 27%). The left ventricle appears dyssynchronous. Delayed-enhancement imaging reveals patchy delayed enhancement in the basal septum and the basal inferolateral walls. These findings suggest cardiac sarcoidosis, with a sensitivity of nearly 100% and a specificity of approximately 78%.¹

SARCOIDOSIS IS A MULTISYSTEM DISEASE

Sarcoidosis is a multisystem disease characterized by noncaseating granulomas. Almost any organ can be affected, but it most commonly involves the respiratory and lymphatic systems.² Although infectious, environmental, and genetic factors have been implicated, the cause remains unknown. The prevalence is approximately 20 per 100,000, being higher in black³ and Japanese ⁴ populations.

CARDIAC SARCOIDOSIS

2. What percentage of patients with sarcoidosis have cardiac involvement?

• 10%–20%
• 20%–30%
• 50%
• 80%

Cardiac involvement is seen in 20% to 30% of patients with sarcoidosis.^5–7 However, most cases are subclinical, and symptomatic cardiac involvement is present in only about 5% of patients with systemic sarcoidosis.⁸ Isolated cardiac sarcoidosis has been described in case reports but is rare.⁹

The clinical manifestations of cardiac sarcoidosis depend on the location and extent of granulomatous inflammation. In a necropsy study of 113 patients with cardiac sarcoidosis, the left ventricular free wall was the most common location, followed by the interventricular septum.¹⁰

3. How does cardiac sarcoidosis most commonly present?

• Conduction abnormalities
• Ventricular tachycardia
• Cardiomyopathy
• Sudden death
• None of the above

Common presentations of cardiac sarcoidosis include conduction system disease and arrhythmias (which can sometimes result in sudden death), and heart failure.

Conduction abnormalities due to granulomas (in the active phase of sarcoidosis) and fibrosis (in the fibrotic phase) in the atrioventricular node or bundle of His are the most common presentation of cardiac sarcoidosis.⁹ These lesions may result in relatively benign first-degree heart block or may be as potentially devastating as complete heart block.

In almost all patients with conduction abnormalities, the basal interventricular septum is involved.¹¹ Patients who develop complete heart block from sarcoidosis tend to be younger than those with idiopathic heart block. Therefore, complete heart block in a young patient should raise the possibility of this diagnosis. ¹²

Ventricular tachycardia (sustained or nonsustained) and ventricular premature beats are the second most common presentation. Up to 22% of patients with sarcoidosis have electrocardiographic evidence of ventricular arrythmias. ¹³ The cause is believed to be myocardial scar tissue resulting from the sarcoid granulomas, leading to electrical reentry.¹⁴ Sudden death due to ventricular tachyarrhythmias or conduction blocks accounts for 25% to 65% of deaths from cardiac sarcoidosis.^9,15,16

Heart failure may result from sarcoidosis when there is extensive granulomatous disease in the myocardium. Depending on the location of the granulomas, both systolic and diastolic dysfunction can occur. In severe cases, extensive granulomas can cause left ventricular aneurysms.

The diagnosis of cardiac sarcoidosis as the cause of heart failure can be difficult to establish, especially in patients without evidence of sarcoidosis elsewhere. Such patients are often given a diagnosis of idiopathic dilated cardiomyopathy. However, compared with patients with idiopathic dilated cardiomyopathy, those with cardiac sarcoidosis have a greater incidence of advanced atrioventricular block, abnormal wall thickness, focal wall motion abnormalities, and perfusion defects of the anteroseptal and apical regions.¹⁷

Progressive heart failure is the second most frequent cause of death (after sudden death) and accounts for 25% to 75% of sarcoid-related cardiac deaths.^9,18,19

DIAGNOSING CARDIAC SARCOIDOSIS

4. How is cardiac sarcoidosis diagnosed?

• Electrocardiography
• Echocardiography
• Computed tomography
• Endomyocardial biopsy
• There are no guidelines for diagnosis

Given the variable extent and location of granulomas in sarcoidosis, the diagnosis of cardiac sarcoidosis is often challenging.

To make the diagnosis of sarcoidosis in general, the American Thoracic Society² says that the clinical picture should be compatible with this diagnosis, noncaseating granulomas should be histologically confirmed, and other diseases capable of producing a similar clinical or histologic picture should be excluded.

A newer diagnostic tool, the Sarcoidosis Three-Dimensional Assessment Instrument,²⁰ incorporates two earlier tools.^20,21 It assesses three axes: organ involvement, sarcoidosis severity, and sarcoidosis activity and categorizes the diagnosis of sarcoidosis as “definite,” “probable,” or “possible.”²⁰

In Japan, where sarcoidosis is more common, the Ministry of Health and Welfare²² says that cardiac sarcoidosis can be diagnosed histologically if operative or endomyocardial biopsy specimens contain noncaseating granuloma. In addition, the diagnosis can be suspected in patients who have a histologic diagnosis of extracardiac sarcoidosis if the first item in the list below and one or more of the rest are present:

• Complete right bundle branch block, left axis deviation, atrioventricular block, ventricular tachycardia, premature ventricular contractions (> grade 2 of the Lown classification), or Q or ST-T wave abnormalities
• Abnormal wall motion, regional wall thinning, or dilation of the left ventricle on echocardiography
• Perfusion defects on thallium 201 myocardial scintigraphy or abnormal accumulation of gallium citrate Ga 67 or technetium 99m on myocardial scintigraphy
• Abnormal intracardiac pressure, low cardiac output, or abnormal wall motion or depressed left ventricular ejection fraction on cardiac catheterization
• Nonspecific interstitial fibrosis or cellular infiltration on myocardial biopsy.

The current diagnostic guidelines from the American Thoracic Society² and the Japanese Ministry of Health and Welfare²² and the Sarcoidosis Three-Dimensional Assessment Instrument,²⁰ however, do not incorporate newer imaging studies as part of their criteria.

A DEFINITIVE DIAGNOSIS

5. Endomyocardial biopsy often provides the definitive diagnosis of cardiac sarcoidosis.

• True
• False

False. Endomyocardial biopsy often fails to reveal noncaseating granulomas, which have a patchy distribution.¹³ Table 2 summarizes the accuracy of tests for cardiac sarcoidosis.

Electrocardiography is abnormal in up to 50% of patients with sarcoidosis,²³ reflecting the conduction disease or arrhythmias commonly seen in cardiac involvement.

Chest radiography classically shows hilar lymphadenopathy and interstitial disease, and may show cardiomegaly, pericardial effusion, or left ventricular aneurysm.

Echocardiography is nonspecific for sarcoid disease, but granulomatous involvement and scar tissue of cardiac tissue may appear hyperechogenic, particularly in the ventricular septum or left ventricular free wall.²⁴

Angiography. Primary sarcoidosis rarely involves the coronary arteries,²⁵ so angiography is most useful in excluding the diagnosis of atherosclerotic coronary artery disease.

Radionuclide imaging with thallium 201 in patients with suspected cardiac sarcoidosis may be useful to suggest myocardial involvement and to exclude cardiac dysfunction secondary to coronary artery disease. Segmental areas with defective thallium 201 uptake correspond to fibrogranulomatous tissue. In resting images, the pattern may be similar to that seen in coronary artery disease. However, during exercise, perfusion defects increase in patients who have ischemia but actually decrease in those with cardiac sarcoidosis.²⁶

Nevertheless, some conclude that thallium scanning is too nonspecific for it to be used as a diagnostic or screening test.^27,28 The combined use of thallium 201 and gallium 67 may better detect cardiac sarcoidosis, as gallium is taken up in areas of active inflammation.

Positron-emission tomography (PET) with fluorodeoxyglucose F 18 (FDG), with the patient fasting, appears to be useful in detecting the early inflammation of cardiac sarcoidosis^29–34 and monitoring disease activity.^30,31 FDG is a glucose analogue that is taken up by granulomatous tissue in the myocardium.³⁴ The uptake in cardiac sarcoidosis is in a focal distribution.^30,31,34 The abnormal FDG uptake resolves with steroid treatment.^31,32

MRI has promise for diagnosing cardiac sarcoidosis. With gadolinium contrast, MRI has superior image resolution and can detect cardiac involvement early in its course.^{27,29,35–44}

Inflammation of the myocardium due to sarcoid involvement appears as focal zones of increased signal intensity on both T2-weighted and early gadolinium T1-weighted images. Late myocardial enhancement after gadolinium infusion is the most typical finding of cardiac sarcoidosis on MRI, and likely represents fibrogranulomatous tissue.²⁷ Delayed gadolinium enhancement is also seen in myocardial infarction but differs in its distribution.^1,35,45 Cardiac sarcoidosis most commonly affects the basal and lateral segments. In one study, the finding of delayed enhancement had a sensitivity of 100% and a specificity of 78%,^1,27 though it may not sufficiently differentiate active inflammation from scar.³⁰

Like FDG-PET, MRI has also been shown to be useful for monitoring treatment.^33,46 However, PET is more useful for follow-up in patients who receive a pacemaker or implantable cardioverter-defibrillator, in whom MRI is contraindicated. One case report²⁹ described using both delayed-enhancement MRI and FDG-PET to diagnose cardiac sarcoidosis.

TREATMENT

6. How is cardiac sarcoidosis currently treated?

• Implantable cardioverter-defibrillator
• Corticosteroids
• Heart transplantation
• All of the above
• None of the above

Corticosteroids

Corticosteroids are the mainstay of treatment of cardiac sarcoidosis, as they attenuate the characteristic inflammation and fibrosis of sarcoid granulomas. The goal is to prevent compromise of cardiac structure or function.⁴⁷ Although most of the supporting data are anecdotal, steroids have been shown to improve ventricular contractility,⁴⁸ arrhythmias,⁴⁹ and conduction abnormalities.⁵⁰ MRI and FDG-PET studies have shown cardiac lesions resolving after steroids were started.^31,45,46

The optimal dosage remains unknown. Initial doses of 30 to 60 mg daily, gradually tapered over 6 to 12 months to maintenance doses of 5 to 10 mg daily, have been effective.^45,51

Relapses are common and require vigilant monitoring.

Alternative agents such as cyclophosphamide (Cytoxan),⁵² methotrexate (Rheumatrex), ⁵³ and cyclosporine (Sandimmune)⁵⁴ can be given to patients whose disease does not respond to corticosteroids or who cannot tolerate their side effects.

Implantable cardioverter-defibrillator

Sudden death due to ventricular tachyarrhythmias or conduction block accounts for 30% to 65% of deaths in patients with cardiac sarcoidosis.¹⁰ The rates of recurrent ventricular tachycardia and sudden death are high, even with antiarrhythmic drug therapy.⁵⁵

Although experience with implantable cardiac defibrillators is limited in patients with cardiac sarcoidosis,^55–58 some have argued that they be strongly considered to prevent sudden cardiac death in this high-risk group.^57,58

Heart transplantation

The largest body of data on transplantation comes from the United Network for Organ Sharing database. In the 65 patients with cardiac sarcoidosis who underwent cardiac transplantation in the 18 years from October 1987 to September 2005, the 1-year post-transplant survival rate was 88%, which was better than in patients with all other diagnoses (85%). The 5-year survival rate was 80%.^59,60

Recurrence of sarcoidosis within the cardiac allograft and transmission of sarcoidosis from donor to recipient have both been documented after heart transplantation.^61,62

CAUSES OF DEATH

7. What is the most common cause of death in patients with cardiac sarcoidosis?

• Respiratory failure
• Conduction disturbances
• Progressive heart failure
• Ventricular tachyarrhythmias
• None of the above

The prognosis of symptomatic cardiac sarcoidosis is not well defined, owing to the variable extent and severity of the disease. The mortality rate in sarcoidosis without cardiac involvement is about 1% to 5% per year.^63,64 Cardiac involvement portends a worse prognosis, with a 55% survival rate at 5 years and 44% at 10 years.^17,65 Most patients in the reported series ultimately died of cardiac complications of sarcoidosis, including ventricular tachyarrhythmias, conduction disturbances, and progressive cardiomyopathy.^10,17

Since corticosteroids, pacemakers, and implantable cardioverter-defibrillators have begun to be used, the cause of death has shifted from sudden death to progressive heart failure.⁶⁶

CASE CONTINUED

Electrophysiologic testing revealed inducible monomorphic sustained ventricular tachycardia. The patient subsequently had a biventricular cardioverter-defibrillator implanted. He was started on an angiotensin-converting enzyme inhibitor and a beta-blocker for his heart failure. Further imaging of his chest and abdomen revealed lesions in his thyroid and liver. As of this writing, he is undergoing further workup. Because of active infection with Clostridium difficile, steroid therapy was deferred.

A 61-year-old white man presents with progressive fatigue, which began several months ago and has accelerated in severity over the past week. He says he has had no shortness of breath, chest pain, or symptoms of heart failure, but he has noticed a decrease in exertional capacity and now has trouble completing his daily 5-mile walk.

He saw his primary physician, who obtained an electrocardiogram that showed a new left bundle branch block. Transthoracic echocardiography indicated that his left ventricular ejection fraction, which was 60% a year earlier, was now 35%.

He has hypertension, dyslipidemia, type 2 diabetes, and chronic kidney disease. Although he was previously morbidly obese, he has lost more than 100 pounds with diet and exercise over the past 10 years. He also used to smoke; in fact, he has a 30-pack-year history, but he quit in 1987. He has a family history of premature coronary artery disease.

Physical examination. His heart rate is 75 beats per minute, blood pressure 142/85 mm Hg, and blood oxygen saturation 96% while breathing room air. He weighs 169 pounds (76.6 kg) and he is 6 feet tall (182.9 cm), so his body mass index is 22.9 kg/m².

Electrocardiography reveals sinus rhythm with a left bundle branch block and left axis deviation (Figure 1), which were not present 1 year ago.

Chest roentgenography is normal.

A WORRISOME PICTURE

1. Which of the following is associated with left bundle branch block?

• Myocardial injury
• Hypertension
• Aortic stenosis
• Intrinsic conduction system disease
• All of the above

All of the above are true. For left bundle branch block to be diagnosed, the rhythm must be supraventricular and the QRS duration must be 120 ms or more. There should be a QS or RS complex in V₁ and a monophasic R wave in I and V₆. Also, the T wave should be deflected opposite the terminal deflection of the QRS complex. This is known as appropriate T-wave discordance with bundle branch block. A concordant T wave is nonspecific but suggests ischemia or myocardial infarction.

Potential causes of a new left bundle branch block include hypertension, acute myocardial infarction, aortic stenosis, and conduction system disease. A new left bundle branch block with a concomitant decrease in ejection fraction, especially in a patient with cardiac risk factors, is very worrisome, raising the possibility of ischemic heart disease.

MORE CARDIAC TESTING

The patient undergoes more cardiac testing.

Transthoracic echocardiography is done again. The left ventricle is normal in size, but the ejection fraction is 35%. In addition, stage 1 diastolic dysfunction (abnormal relaxation) and evidence of mechanical dyssynchrony (disruption in the normal sequence of activation and contraction of segments of the left ventricular wall) are seen. The right ventricle is normal in size and function. There is trivial mitral regurgitation and mild tricuspid regurgitation with normal right-sided pressures.

A gated rubidium-82 dipyridamole stress test yields no evidence of a fixed or reversible perfusion defect.

Left heart catheterization reveals angiographically normal coronary arteries.

Magnetic resonance imaging (MRI) shows a moderately hypertrophied left ventricle with moderately to severely depressed systolic function (left ventricular ejection fraction 27%). The left ventricle appears dyssynchronous. Delayed-enhancement imaging reveals patchy delayed enhancement in the basal septum and the basal inferolateral walls. These findings suggest cardiac sarcoidosis, with a sensitivity of nearly 100% and a specificity of approximately 78%.¹

SARCOIDOSIS IS A MULTISYSTEM DISEASE

Sarcoidosis is a multisystem disease characterized by noncaseating granulomas. Almost any organ can be affected, but it most commonly involves the respiratory and lymphatic systems.² Although infectious, environmental, and genetic factors have been implicated, the cause remains unknown. The prevalence is approximately 20 per 100,000, being higher in black³ and Japanese ⁴ populations.

CARDIAC SARCOIDOSIS

2. What percentage of patients with sarcoidosis have cardiac involvement?

• 10%–20%
• 20%–30%
• 50%
• 80%

Cardiac involvement is seen in 20% to 30% of patients with sarcoidosis.^5–7 However, most cases are subclinical, and symptomatic cardiac involvement is present in only about 5% of patients with systemic sarcoidosis.⁸ Isolated cardiac sarcoidosis has been described in case reports but is rare.⁹

The clinical manifestations of cardiac sarcoidosis depend on the location and extent of granulomatous inflammation. In a necropsy study of 113 patients with cardiac sarcoidosis, the left ventricular free wall was the most common location, followed by the interventricular septum.¹⁰

3. How does cardiac sarcoidosis most commonly present?

• Conduction abnormalities
• Ventricular tachycardia
• Cardiomyopathy
• Sudden death
• None of the above

Common presentations of cardiac sarcoidosis include conduction system disease and arrhythmias (which can sometimes result in sudden death), and heart failure.

Conduction abnormalities due to granulomas (in the active phase of sarcoidosis) and fibrosis (in the fibrotic phase) in the atrioventricular node or bundle of His are the most common presentation of cardiac sarcoidosis.⁹ These lesions may result in relatively benign first-degree heart block or may be as potentially devastating as complete heart block.

In almost all patients with conduction abnormalities, the basal interventricular septum is involved.¹¹ Patients who develop complete heart block from sarcoidosis tend to be younger than those with idiopathic heart block. Therefore, complete heart block in a young patient should raise the possibility of this diagnosis. ¹²

Ventricular tachycardia (sustained or nonsustained) and ventricular premature beats are the second most common presentation. Up to 22% of patients with sarcoidosis have electrocardiographic evidence of ventricular arrythmias. ¹³ The cause is believed to be myocardial scar tissue resulting from the sarcoid granulomas, leading to electrical reentry.¹⁴ Sudden death due to ventricular tachyarrhythmias or conduction blocks accounts for 25% to 65% of deaths from cardiac sarcoidosis.^9,15,16

Heart failure may result from sarcoidosis when there is extensive granulomatous disease in the myocardium. Depending on the location of the granulomas, both systolic and diastolic dysfunction can occur. In severe cases, extensive granulomas can cause left ventricular aneurysms.

The diagnosis of cardiac sarcoidosis as the cause of heart failure can be difficult to establish, especially in patients without evidence of sarcoidosis elsewhere. Such patients are often given a diagnosis of idiopathic dilated cardiomyopathy. However, compared with patients with idiopathic dilated cardiomyopathy, those with cardiac sarcoidosis have a greater incidence of advanced atrioventricular block, abnormal wall thickness, focal wall motion abnormalities, and perfusion defects of the anteroseptal and apical regions.¹⁷

Progressive heart failure is the second most frequent cause of death (after sudden death) and accounts for 25% to 75% of sarcoid-related cardiac deaths.^9,18,19

DIAGNOSING CARDIAC SARCOIDOSIS

4. How is cardiac sarcoidosis diagnosed?

• Electrocardiography
• Echocardiography
• Computed tomography
• Endomyocardial biopsy
• There are no guidelines for diagnosis

Given the variable extent and location of granulomas in sarcoidosis, the diagnosis of cardiac sarcoidosis is often challenging.

To make the diagnosis of sarcoidosis in general, the American Thoracic Society² says that the clinical picture should be compatible with this diagnosis, noncaseating granulomas should be histologically confirmed, and other diseases capable of producing a similar clinical or histologic picture should be excluded.

A newer diagnostic tool, the Sarcoidosis Three-Dimensional Assessment Instrument,²⁰ incorporates two earlier tools.^20,21 It assesses three axes: organ involvement, sarcoidosis severity, and sarcoidosis activity and categorizes the diagnosis of sarcoidosis as “definite,” “probable,” or “possible.”²⁰

In Japan, where sarcoidosis is more common, the Ministry of Health and Welfare²² says that cardiac sarcoidosis can be diagnosed histologically if operative or endomyocardial biopsy specimens contain noncaseating granuloma. In addition, the diagnosis can be suspected in patients who have a histologic diagnosis of extracardiac sarcoidosis if the first item in the list below and one or more of the rest are present:

• Complete right bundle branch block, left axis deviation, atrioventricular block, ventricular tachycardia, premature ventricular contractions (> grade 2 of the Lown classification), or Q or ST-T wave abnormalities
• Abnormal wall motion, regional wall thinning, or dilation of the left ventricle on echocardiography
• Perfusion defects on thallium 201 myocardial scintigraphy or abnormal accumulation of gallium citrate Ga 67 or technetium 99m on myocardial scintigraphy
• Abnormal intracardiac pressure, low cardiac output, or abnormal wall motion or depressed left ventricular ejection fraction on cardiac catheterization
• Nonspecific interstitial fibrosis or cellular infiltration on myocardial biopsy.

The current diagnostic guidelines from the American Thoracic Society² and the Japanese Ministry of Health and Welfare²² and the Sarcoidosis Three-Dimensional Assessment Instrument,²⁰ however, do not incorporate newer imaging studies as part of their criteria.

A DEFINITIVE DIAGNOSIS

5. Endomyocardial biopsy often provides the definitive diagnosis of cardiac sarcoidosis.

• True
• False

False. Endomyocardial biopsy often fails to reveal noncaseating granulomas, which have a patchy distribution.¹³ Table 2 summarizes the accuracy of tests for cardiac sarcoidosis.

Electrocardiography is abnormal in up to 50% of patients with sarcoidosis,²³ reflecting the conduction disease or arrhythmias commonly seen in cardiac involvement.

Chest radiography classically shows hilar lymphadenopathy and interstitial disease, and may show cardiomegaly, pericardial effusion, or left ventricular aneurysm.

Echocardiography is nonspecific for sarcoid disease, but granulomatous involvement and scar tissue of cardiac tissue may appear hyperechogenic, particularly in the ventricular septum or left ventricular free wall.²⁴

Angiography. Primary sarcoidosis rarely involves the coronary arteries,²⁵ so angiography is most useful in excluding the diagnosis of atherosclerotic coronary artery disease.

Radionuclide imaging with thallium 201 in patients with suspected cardiac sarcoidosis may be useful to suggest myocardial involvement and to exclude cardiac dysfunction secondary to coronary artery disease. Segmental areas with defective thallium 201 uptake correspond to fibrogranulomatous tissue. In resting images, the pattern may be similar to that seen in coronary artery disease. However, during exercise, perfusion defects increase in patients who have ischemia but actually decrease in those with cardiac sarcoidosis.²⁶

Nevertheless, some conclude that thallium scanning is too nonspecific for it to be used as a diagnostic or screening test.^27,28 The combined use of thallium 201 and gallium 67 may better detect cardiac sarcoidosis, as gallium is taken up in areas of active inflammation.

Positron-emission tomography (PET) with fluorodeoxyglucose F 18 (FDG), with the patient fasting, appears to be useful in detecting the early inflammation of cardiac sarcoidosis^29–34 and monitoring disease activity.^30,31 FDG is a glucose analogue that is taken up by granulomatous tissue in the myocardium.³⁴ The uptake in cardiac sarcoidosis is in a focal distribution.^30,31,34 The abnormal FDG uptake resolves with steroid treatment.^31,32

MRI has promise for diagnosing cardiac sarcoidosis. With gadolinium contrast, MRI has superior image resolution and can detect cardiac involvement early in its course.^{27,29,35–44}

Inflammation of the myocardium due to sarcoid involvement appears as focal zones of increased signal intensity on both T2-weighted and early gadolinium T1-weighted images. Late myocardial enhancement after gadolinium infusion is the most typical finding of cardiac sarcoidosis on MRI, and likely represents fibrogranulomatous tissue.²⁷ Delayed gadolinium enhancement is also seen in myocardial infarction but differs in its distribution.^1,35,45 Cardiac sarcoidosis most commonly affects the basal and lateral segments. In one study, the finding of delayed enhancement had a sensitivity of 100% and a specificity of 78%,^1,27 though it may not sufficiently differentiate active inflammation from scar.³⁰

Like FDG-PET, MRI has also been shown to be useful for monitoring treatment.^33,46 However, PET is more useful for follow-up in patients who receive a pacemaker or implantable cardioverter-defibrillator, in whom MRI is contraindicated. One case report²⁹ described using both delayed-enhancement MRI and FDG-PET to diagnose cardiac sarcoidosis.

TREATMENT

6. How is cardiac sarcoidosis currently treated?

• Implantable cardioverter-defibrillator
• Corticosteroids
• Heart transplantation
• All of the above
• None of the above

Corticosteroids

Corticosteroids are the mainstay of treatment of cardiac sarcoidosis, as they attenuate the characteristic inflammation and fibrosis of sarcoid granulomas. The goal is to prevent compromise of cardiac structure or function.⁴⁷ Although most of the supporting data are anecdotal, steroids have been shown to improve ventricular contractility,⁴⁸ arrhythmias,⁴⁹ and conduction abnormalities.⁵⁰ MRI and FDG-PET studies have shown cardiac lesions resolving after steroids were started.^31,45,46

The optimal dosage remains unknown. Initial doses of 30 to 60 mg daily, gradually tapered over 6 to 12 months to maintenance doses of 5 to 10 mg daily, have been effective.^45,51

Relapses are common and require vigilant monitoring.

Alternative agents such as cyclophosphamide (Cytoxan),⁵² methotrexate (Rheumatrex), ⁵³ and cyclosporine (Sandimmune)⁵⁴ can be given to patients whose disease does not respond to corticosteroids or who cannot tolerate their side effects.

Implantable cardioverter-defibrillator

Sudden death due to ventricular tachyarrhythmias or conduction block accounts for 30% to 65% of deaths in patients with cardiac sarcoidosis.¹⁰ The rates of recurrent ventricular tachycardia and sudden death are high, even with antiarrhythmic drug therapy.⁵⁵

Although experience with implantable cardiac defibrillators is limited in patients with cardiac sarcoidosis,^55–58 some have argued that they be strongly considered to prevent sudden cardiac death in this high-risk group.^57,58

Heart transplantation

The largest body of data on transplantation comes from the United Network for Organ Sharing database. In the 65 patients with cardiac sarcoidosis who underwent cardiac transplantation in the 18 years from October 1987 to September 2005, the 1-year post-transplant survival rate was 88%, which was better than in patients with all other diagnoses (85%). The 5-year survival rate was 80%.^59,60

Recurrence of sarcoidosis within the cardiac allograft and transmission of sarcoidosis from donor to recipient have both been documented after heart transplantation.^61,62

CAUSES OF DEATH

7. What is the most common cause of death in patients with cardiac sarcoidosis?

• Respiratory failure
• Conduction disturbances
• Progressive heart failure
• Ventricular tachyarrhythmias
• None of the above

The prognosis of symptomatic cardiac sarcoidosis is not well defined, owing to the variable extent and severity of the disease. The mortality rate in sarcoidosis without cardiac involvement is about 1% to 5% per year.^63,64 Cardiac involvement portends a worse prognosis, with a 55% survival rate at 5 years and 44% at 10 years.^17,65 Most patients in the reported series ultimately died of cardiac complications of sarcoidosis, including ventricular tachyarrhythmias, conduction disturbances, and progressive cardiomyopathy.^10,17

Since corticosteroids, pacemakers, and implantable cardioverter-defibrillators have begun to be used, the cause of death has shifted from sudden death to progressive heart failure.⁶⁶

CASE CONTINUED

Electrophysiologic testing revealed inducible monomorphic sustained ventricular tachycardia. The patient subsequently had a biventricular cardioverter-defibrillator implanted. He was started on an angiotensin-converting enzyme inhibitor and a beta-blocker for his heart failure. Further imaging of his chest and abdomen revealed lesions in his thyroid and liver. As of this writing, he is undergoing further workup. Because of active infection with Clostridium difficile, steroid therapy was deferred.

A 61-year-old white man presents with progressive fatigue, which began several months ago and has accelerated in severity over the past week. He says he has had no shortness of breath, chest pain, or symptoms of heart failure, but he has noticed a decrease in exertional capacity and now has trouble completing his daily 5-mile walk.

He saw his primary physician, who obtained an electrocardiogram that showed a new left bundle branch block. Transthoracic echocardiography indicated that his left ventricular ejection fraction, which was 60% a year earlier, was now 35%.

He has hypertension, dyslipidemia, type 2 diabetes, and chronic kidney disease. Although he was previously morbidly obese, he has lost more than 100 pounds with diet and exercise over the past 10 years. He also used to smoke; in fact, he has a 30-pack-year history, but he quit in 1987. He has a family history of premature coronary artery disease.

Physical examination. His heart rate is 75 beats per minute, blood pressure 142/85 mm Hg, and blood oxygen saturation 96% while breathing room air. He weighs 169 pounds (76.6 kg) and he is 6 feet tall (182.9 cm), so his body mass index is 22.9 kg/m².

Electrocardiography reveals sinus rhythm with a left bundle branch block and left axis deviation (Figure 1), which were not present 1 year ago.

Chest roentgenography is normal.

A WORRISOME PICTURE

1. Which of the following is associated with left bundle branch block?

• Myocardial injury
• Hypertension
• Aortic stenosis
• Intrinsic conduction system disease
• All of the above

All of the above are true. For left bundle branch block to be diagnosed, the rhythm must be supraventricular and the QRS duration must be 120 ms or more. There should be a QS or RS complex in V₁ and a monophasic R wave in I and V₆. Also, the T wave should be deflected opposite the terminal deflection of the QRS complex. This is known as appropriate T-wave discordance with bundle branch block. A concordant T wave is nonspecific but suggests ischemia or myocardial infarction.

Potential causes of a new left bundle branch block include hypertension, acute myocardial infarction, aortic stenosis, and conduction system disease. A new left bundle branch block with a concomitant decrease in ejection fraction, especially in a patient with cardiac risk factors, is very worrisome, raising the possibility of ischemic heart disease.

MORE CARDIAC TESTING

The patient undergoes more cardiac testing.

Transthoracic echocardiography is done again. The left ventricle is normal in size, but the ejection fraction is 35%. In addition, stage 1 diastolic dysfunction (abnormal relaxation) and evidence of mechanical dyssynchrony (disruption in the normal sequence of activation and contraction of segments of the left ventricular wall) are seen. The right ventricle is normal in size and function. There is trivial mitral regurgitation and mild tricuspid regurgitation with normal right-sided pressures.

A gated rubidium-82 dipyridamole stress test yields no evidence of a fixed or reversible perfusion defect.

Left heart catheterization reveals angiographically normal coronary arteries.

Magnetic resonance imaging (MRI) shows a moderately hypertrophied left ventricle with moderately to severely depressed systolic function (left ventricular ejection fraction 27%). The left ventricle appears dyssynchronous. Delayed-enhancement imaging reveals patchy delayed enhancement in the basal septum and the basal inferolateral walls. These findings suggest cardiac sarcoidosis, with a sensitivity of nearly 100% and a specificity of approximately 78%.¹

SARCOIDOSIS IS A MULTISYSTEM DISEASE

Sarcoidosis is a multisystem disease characterized by noncaseating granulomas. Almost any organ can be affected, but it most commonly involves the respiratory and lymphatic systems.² Although infectious, environmental, and genetic factors have been implicated, the cause remains unknown. The prevalence is approximately 20 per 100,000, being higher in black³ and Japanese ⁴ populations.

CARDIAC SARCOIDOSIS

2. What percentage of patients with sarcoidosis have cardiac involvement?

• 10%–20%
• 20%–30%
• 50%
• 80%

Cardiac involvement is seen in 20% to 30% of patients with sarcoidosis.^5–7 However, most cases are subclinical, and symptomatic cardiac involvement is present in only about 5% of patients with systemic sarcoidosis.⁸ Isolated cardiac sarcoidosis has been described in case reports but is rare.⁹

The clinical manifestations of cardiac sarcoidosis depend on the location and extent of granulomatous inflammation. In a necropsy study of 113 patients with cardiac sarcoidosis, the left ventricular free wall was the most common location, followed by the interventricular septum.¹⁰

3. How does cardiac sarcoidosis most commonly present?

• Conduction abnormalities
• Ventricular tachycardia
• Cardiomyopathy
• Sudden death
• None of the above

Common presentations of cardiac sarcoidosis include conduction system disease and arrhythmias (which can sometimes result in sudden death), and heart failure.

Conduction abnormalities due to granulomas (in the active phase of sarcoidosis) and fibrosis (in the fibrotic phase) in the atrioventricular node or bundle of His are the most common presentation of cardiac sarcoidosis.⁹ These lesions may result in relatively benign first-degree heart block or may be as potentially devastating as complete heart block.

In almost all patients with conduction abnormalities, the basal interventricular septum is involved.¹¹ Patients who develop complete heart block from sarcoidosis tend to be younger than those with idiopathic heart block. Therefore, complete heart block in a young patient should raise the possibility of this diagnosis. ¹²

Ventricular tachycardia (sustained or nonsustained) and ventricular premature beats are the second most common presentation. Up to 22% of patients with sarcoidosis have electrocardiographic evidence of ventricular arrythmias. ¹³ The cause is believed to be myocardial scar tissue resulting from the sarcoid granulomas, leading to electrical reentry.¹⁴ Sudden death due to ventricular tachyarrhythmias or conduction blocks accounts for 25% to 65% of deaths from cardiac sarcoidosis.^9,15,16

Heart failure may result from sarcoidosis when there is extensive granulomatous disease in the myocardium. Depending on the location of the granulomas, both systolic and diastolic dysfunction can occur. In severe cases, extensive granulomas can cause left ventricular aneurysms.

The diagnosis of cardiac sarcoidosis as the cause of heart failure can be difficult to establish, especially in patients without evidence of sarcoidosis elsewhere. Such patients are often given a diagnosis of idiopathic dilated cardiomyopathy. However, compared with patients with idiopathic dilated cardiomyopathy, those with cardiac sarcoidosis have a greater incidence of advanced atrioventricular block, abnormal wall thickness, focal wall motion abnormalities, and perfusion defects of the anteroseptal and apical regions.¹⁷

Progressive heart failure is the second most frequent cause of death (after sudden death) and accounts for 25% to 75% of sarcoid-related cardiac deaths.^9,18,19

DIAGNOSING CARDIAC SARCOIDOSIS

4. How is cardiac sarcoidosis diagnosed?

• Electrocardiography
• Echocardiography
• Computed tomography
• Endomyocardial biopsy
• There are no guidelines for diagnosis

Given the variable extent and location of granulomas in sarcoidosis, the diagnosis of cardiac sarcoidosis is often challenging.

To make the diagnosis of sarcoidosis in general, the American Thoracic Society² says that the clinical picture should be compatible with this diagnosis, noncaseating granulomas should be histologically confirmed, and other diseases capable of producing a similar clinical or histologic picture should be excluded.

A newer diagnostic tool, the Sarcoidosis Three-Dimensional Assessment Instrument,²⁰ incorporates two earlier tools.^20,21 It assesses three axes: organ involvement, sarcoidosis severity, and sarcoidosis activity and categorizes the diagnosis of sarcoidosis as “definite,” “probable,” or “possible.”²⁰

In Japan, where sarcoidosis is more common, the Ministry of Health and Welfare²² says that cardiac sarcoidosis can be diagnosed histologically if operative or endomyocardial biopsy specimens contain noncaseating granuloma. In addition, the diagnosis can be suspected in patients who have a histologic diagnosis of extracardiac sarcoidosis if the first item in the list below and one or more of the rest are present:

• Complete right bundle branch block, left axis deviation, atrioventricular block, ventricular tachycardia, premature ventricular contractions (> grade 2 of the Lown classification), or Q or ST-T wave abnormalities
• Abnormal wall motion, regional wall thinning, or dilation of the left ventricle on echocardiography
• Perfusion defects on thallium 201 myocardial scintigraphy or abnormal accumulation of gallium citrate Ga 67 or technetium 99m on myocardial scintigraphy
• Abnormal intracardiac pressure, low cardiac output, or abnormal wall motion or depressed left ventricular ejection fraction on cardiac catheterization
• Nonspecific interstitial fibrosis or cellular infiltration on myocardial biopsy.

The current diagnostic guidelines from the American Thoracic Society² and the Japanese Ministry of Health and Welfare²² and the Sarcoidosis Three-Dimensional Assessment Instrument,²⁰ however, do not incorporate newer imaging studies as part of their criteria.

A DEFINITIVE DIAGNOSIS

5. Endomyocardial biopsy often provides the definitive diagnosis of cardiac sarcoidosis.

• True
• False

False. Endomyocardial biopsy often fails to reveal noncaseating granulomas, which have a patchy distribution.¹³ Table 2 summarizes the accuracy of tests for cardiac sarcoidosis.

Electrocardiography is abnormal in up to 50% of patients with sarcoidosis,²³ reflecting the conduction disease or arrhythmias commonly seen in cardiac involvement.

Chest radiography classically shows hilar lymphadenopathy and interstitial disease, and may show cardiomegaly, pericardial effusion, or left ventricular aneurysm.

Echocardiography is nonspecific for sarcoid disease, but granulomatous involvement and scar tissue of cardiac tissue may appear hyperechogenic, particularly in the ventricular septum or left ventricular free wall.²⁴

Angiography. Primary sarcoidosis rarely involves the coronary arteries,²⁵ so angiography is most useful in excluding the diagnosis of atherosclerotic coronary artery disease.

Radionuclide imaging with thallium 201 in patients with suspected cardiac sarcoidosis may be useful to suggest myocardial involvement and to exclude cardiac dysfunction secondary to coronary artery disease. Segmental areas with defective thallium 201 uptake correspond to fibrogranulomatous tissue. In resting images, the pattern may be similar to that seen in coronary artery disease. However, during exercise, perfusion defects increase in patients who have ischemia but actually decrease in those with cardiac sarcoidosis.²⁶

Nevertheless, some conclude that thallium scanning is too nonspecific for it to be used as a diagnostic or screening test.^27,28 The combined use of thallium 201 and gallium 67 may better detect cardiac sarcoidosis, as gallium is taken up in areas of active inflammation.

Positron-emission tomography (PET) with fluorodeoxyglucose F 18 (FDG), with the patient fasting, appears to be useful in detecting the early inflammation of cardiac sarcoidosis^29–34 and monitoring disease activity.^30,31 FDG is a glucose analogue that is taken up by granulomatous tissue in the myocardium.³⁴ The uptake in cardiac sarcoidosis is in a focal distribution.^30,31,34 The abnormal FDG uptake resolves with steroid treatment.^31,32

MRI has promise for diagnosing cardiac sarcoidosis. With gadolinium contrast, MRI has superior image resolution and can detect cardiac involvement early in its course.^{27,29,35–44}

Inflammation of the myocardium due to sarcoid involvement appears as focal zones of increased signal intensity on both T2-weighted and early gadolinium T1-weighted images. Late myocardial enhancement after gadolinium infusion is the most typical finding of cardiac sarcoidosis on MRI, and likely represents fibrogranulomatous tissue.²⁷ Delayed gadolinium enhancement is also seen in myocardial infarction but differs in its distribution.^1,35,45 Cardiac sarcoidosis most commonly affects the basal and lateral segments. In one study, the finding of delayed enhancement had a sensitivity of 100% and a specificity of 78%,^1,27 though it may not sufficiently differentiate active inflammation from scar.³⁰

Like FDG-PET, MRI has also been shown to be useful for monitoring treatment.^33,46 However, PET is more useful for follow-up in patients who receive a pacemaker or implantable cardioverter-defibrillator, in whom MRI is contraindicated. One case report²⁹ described using both delayed-enhancement MRI and FDG-PET to diagnose cardiac sarcoidosis.

TREATMENT

6. How is cardiac sarcoidosis currently treated?

• Implantable cardioverter-defibrillator
• Corticosteroids
• Heart transplantation
• All of the above
• None of the above

Corticosteroids

Corticosteroids are the mainstay of treatment of cardiac sarcoidosis, as they attenuate the characteristic inflammation and fibrosis of sarcoid granulomas. The goal is to prevent compromise of cardiac structure or function.⁴⁷ Although most of the supporting data are anecdotal, steroids have been shown to improve ventricular contractility,⁴⁸ arrhythmias,⁴⁹ and conduction abnormalities.⁵⁰ MRI and FDG-PET studies have shown cardiac lesions resolving after steroids were started.^31,45,46

The optimal dosage remains unknown. Initial doses of 30 to 60 mg daily, gradually tapered over 6 to 12 months to maintenance doses of 5 to 10 mg daily, have been effective.^45,51

Relapses are common and require vigilant monitoring.

Alternative agents such as cyclophosphamide (Cytoxan),⁵² methotrexate (Rheumatrex), ⁵³ and cyclosporine (Sandimmune)⁵⁴ can be given to patients whose disease does not respond to corticosteroids or who cannot tolerate their side effects.

Implantable cardioverter-defibrillator

Sudden death due to ventricular tachyarrhythmias or conduction block accounts for 30% to 65% of deaths in patients with cardiac sarcoidosis.¹⁰ The rates of recurrent ventricular tachycardia and sudden death are high, even with antiarrhythmic drug therapy.⁵⁵

Although experience with implantable cardiac defibrillators is limited in patients with cardiac sarcoidosis,^55–58 some have argued that they be strongly considered to prevent sudden cardiac death in this high-risk group.^57,58

Heart transplantation

The largest body of data on transplantation comes from the United Network for Organ Sharing database. In the 65 patients with cardiac sarcoidosis who underwent cardiac transplantation in the 18 years from October 1987 to September 2005, the 1-year post-transplant survival rate was 88%, which was better than in patients with all other diagnoses (85%). The 5-year survival rate was 80%.^59,60

Recurrence of sarcoidosis within the cardiac allograft and transmission of sarcoidosis from donor to recipient have both been documented after heart transplantation.^61,62

CAUSES OF DEATH

7. What is the most common cause of death in patients with cardiac sarcoidosis?

• Respiratory failure
• Conduction disturbances
• Progressive heart failure
• Ventricular tachyarrhythmias
• None of the above

The prognosis of symptomatic cardiac sarcoidosis is not well defined, owing to the variable extent and severity of the disease. The mortality rate in sarcoidosis without cardiac involvement is about 1% to 5% per year.^63,64 Cardiac involvement portends a worse prognosis, with a 55% survival rate at 5 years and 44% at 10 years.^17,65 Most patients in the reported series ultimately died of cardiac complications of sarcoidosis, including ventricular tachyarrhythmias, conduction disturbances, and progressive cardiomyopathy.^10,17

Since corticosteroids, pacemakers, and implantable cardioverter-defibrillators have begun to be used, the cause of death has shifted from sudden death to progressive heart failure.⁶⁶

CASE CONTINUED

Electrophysiologic testing revealed inducible monomorphic sustained ventricular tachycardia. The patient subsequently had a biventricular cardioverter-defibrillator implanted. He was started on an angiotensin-converting enzyme inhibitor and a beta-blocker for his heart failure. Further imaging of his chest and abdomen revealed lesions in his thyroid and liver. As of this writing, he is undergoing further workup. Because of active infection with Clostridium difficile, steroid therapy was deferred.