Greater involvement of the patient and family in decision-making, clarity on the role of genetic testing and parameters for team-oriented care, and use of high-volume specialty centers are cornerstones of the first update in almost a decade of the American Heart Association/American College of Cardiology guideline for patients with hypertrophic cardiomyopathy (HCM).
Dr. Seema Mital
The update lists 133 recommendations for HCM care in six categories: shared decision-making; role of high-volume HCM centers; diagnosis, initial evaluation, and follow-up; risk assessment and prevention of sudden cardiac death (SCD); management of HCM; and lifestyle considerations for patients.
“The guideline puts the patient front and center in the shared decision-making process and emphasizes the importance of incorporating patient’s lifestyle choices and preferences when making complex, life-altering decisions,” writing committee vice chair Seema Mital, MD, of the University of Toronto and the Hospital for Sick Children, also in Toronto, said in an interview.
The fully updated guideline, authored by a joint committee of the AHA and ACC with input from other specialty societies, has been published online in the Journal of the American College of Cardiology. It replaces the 2011 guideline.
Another key component of the update is the strong recommendation to utilize multidisciplinary care, said Matthew W. Martinez, MD, a writing committee member and sports cardiologists at Morristown (N.J.) Medical Center. “This is not only as a part of shared decision-making, but really in care for the patients,” he said, “that there’s a level of expertise that is provided by centers of excellence who handle HCM, and we did lay out some recommendations with regards to surgery, imaging, interventionists, and management with electrophysiology, and the care of athletes with potential for HCM and pregnant women.”
Dr. Matthew W. Martinez
The update ranks recommendations by class of recommendation (COR), ranging from strong benefit much greater than risk to harm with risk exceeding benefit, and level of evidence (LOE). The recommendation for shared decision making, for example, carries at COR of 1, the highest rating, and a mid-level LOE of B-NR, meaning from nonrandomized studies. Patients who need septal reduction therapy (SRT) should be referred to a comprehensive or primary HCM center – a recommendation with a COR of 1 but an LOE of C-LD, meaning there are limited data.
From diagnosis to follow-up
The most extensive list of recommendations falls under the category covering diagnosis, initial evaluation and follow-up. They include a three-generation family history as part of the initial diagnostic assessment (COR, 1; LOE, B-NR), high-level recommendations for use of transthoracic echocardiogram in the initial work-up, every 1 or 2 years or when the patient’s status changes in confirmed cases, as well as parameters for using other imaging and diagnostic tests. Cardiovascular MRI, for example, is indicated when echocardiography is inconclusive (COR, 1; LOE, B-NR) and in other scenarios. When echocardiography is inconclusive but cardiac MRI isn’t available, cardiac CT is an option, albeit at a lower level of evidence (COR, 2b; LOE, C-LD).
Heart rhythm assessment has a high level of recommendation in multiple scenarios, even in first-degree relatives of HCM patients. Invasive hemodynamic assessment is in order for candidates of SRT whose left ventricular (LV) outflow tract obstruction status is unknown. This category also sets parameters for angiography, and exercise stress testing.
The most extensive recommendations for diagnosis and follow-up cover genetic testing; it consists of nine high-level recommendations.
“The guideline highlights not only the importance of genetic testing of an affected patient and genetic screening of family members, but also emphasizes ongoing reassessment of variant classification as this may evolve with time and change how we recommend ongoing family screening,” Dr. Mital noted.
“The guideline proposes initiating screening of family members at the earliest regardless of age given HCM can manifest at any age in affected families,” she added.
The guideline notes that the usefulness of genetic testing to evaluate the risk of sudden cardiac death (SCD) is uncertain. There’s even guidance for implementing those test results. Further testing is recommended for patients who are genotype positive and phenotype negative for HCM (COR, 1; LOE, B-NR). Those same patients may participate in competitive sports (COR, 2a; LOE, C-LD), but a pacemaker isn’t recommended as a primary prevention (COR, 3 [no benefit]; LOE, B-NR).
Risk evaluation and prevention
For SCD risk evaluation and prevention, the guideline spells out five components for the initial and follow-up evaluations (COR, 1; LOE, B-NR). That includes maximal LV wall thickness, ejection fraction, and LV apical aneurysm. The section include multiple recommendations for patient selection for placement of an implantable cardioverter-defibrillator (ICD). For example, it’s recommended for patient’s who’ve had a heart attack or sustained ventricular tachycardia (COR, 1; LOE, B-NR), but not so much for patients without risk factors or for participating in sports (COR, 3 [harm]; LOE, B-NR). The guideline even provides recommendations for selecting an ICD.
Management recommendations address when medical therapy is indicated, including which therapies are indicated for specific scenarios, as well as higher level interventions such as SRT for severely symptomatic patients with obstructive HCM (COR, 2b; LOE, C-LD) and surgical myectomy with ablation in patients with HCM and atrial fibrillation (COR, 2a; LOE, B-NR). This section also provides recommendations for managing patients with HCM and ventricular arrhythmias or advanced heart failure.
The guideline also includes a host of lifestyle considerations. Mild to moderate exercise is beneficial (COR, 1; LOE, B-NR), but athletes with HCM should consult with an “expert provider” (COR, 1; LOE, C, meaning based on expert opinion). Truck drivers, pilots and people who do strenuous physical labor with HCM should meet specific standards.
These recommendations again emphasize the role of shared decision-making, said Dr. Martinez. “It’s not a cookie-cutter discussion. It is taking all of the information, incorporating what the patient’s needs are, and then making sure you appropriately tell them what are the risks of exercising and not exercising. I have as many discussions through the day about what the risks of exercise are as I do the risks of not exercising.”
Refining nomenclature, pathophysiology
The writing committee addressed the nomenclature for HCM. The use of HCM to describe increased LV wall thickness linked to systemic diseases or secondary to LV hypertrophy “can lead to confusion,” the committee stated, so other cardiac or systemic causes of LV hypertrophy shouldn’t be labeled HCM. Other etiologies can cause secondary LV hypertrophy that can overlap with HCM; clinical markers and testing can help differentiate these mimickers from HCM. When echocardiography is inconclusive, cardiovascular MRI is indicated (COR, 1; LOE, B-NR).
The guideline update also provides clarity on the pathophysiology of HCM: It consists of dynamic LV outflow tract obstruction, mitral regurgitation, diastolic dysfunction, myocardial ischemia, arrhythmias, or autonomic dysfunction. “For a given patient with HCM, the clinical outcome may be dominated by one of these components or may be the result of a complex interplay,” the guideline states. The clinical evaluation should consider all these conditions.
This update also provides “clear separation” between care of HCM with and without obstruction, Dr. Martinez said. “The role of advanced therapies and referrals with advanced treatment options such as heart transplantation or CRT therapy in this group is different than before, recognizing that people with obstruction have symptoms that may be similar to those without obstruction, and the individual should be [thoroughly] investigated to make sure that you can discern between those two groups to make appropriate recommendations.”
The guideline was developed in collaboration with and endorsed by the American Association for Thoracic Surgery, American Society of Echocardiography, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society for Cardiovascular Magnetic Resonance. It’s also been endorsed by the Pediatric & Congenital Electrophysiology Society.
Dr. Mital and Dr. Martinez have no relevant financial relationships to disclose.
SOURCE: Mital S et al. J Am Coll Cardiol. 2020 Nov 20. doi: 10.1016/j.jacc.2020.08.044.