DIAGNOSTIC EVALUATION A complete patient history and thorough review of systems will enable the clinician to identify the risk factors for A-fib and establish a diagnosis (see Table 1).1,4,5 Evaluation should also include a detailed physical examination. Upon initial cardiovascular assessment, the patient’s apical pulse may be rapid, irregular, or disorganized during auscultation. If underlying A-fib is related to a valvular abnormality, an audible murmur may be auscultated.5
Workup for A-fib includes the standard 12-lead ECG, chest radiograph, thyroid function test, and echocardiogram. The 12-lead ECG is definitive for making the diagnosis of A-fib (see Figure 1). A-fib is characterized by irregular R-R intervals when atrioventricular conduction is present, absence of distinct repeating P waves, and irregular atrial activity.1
If the patient describes episodes consistent with A-fib that is not detectable at the office visit, 24- or 48-hour ambulatory Holter monitoring may be revealing. Event monitors can be used to determine the frequency with which the patient experiences A-fib over an extended period of time (up to 30 days).6
As part of the differential diagnosis of A-fib, clinicians need to consider other possible atrial conduction abnormalities, including atrial flutter, atrial tachycardia, atrioventricular nodal reentry tachycardia, multifocal atrial tachycardia, and Wolff-Parkinson-White syndrome.5
To rule out other etiologies, consider performing the following examinations and tests4
• A chest x-ray can rule out undiagnosed lung disease (eg, chronic obstructive pulmonary disease). • To exclude hyperthyroidism as a cause of the patient’s symptoms, thyroid function testing and a physical examination for exophthalmos, carotid bruits, and thyromegaly are needed. • Echocardiography is useful to exclude valvular abnormalities and/or heart failure. • A complete blood cell count will rule out any infectious process or anemic state. • Renal function studies and a comprehensive metabolic panel will detect signs of renal failure or electrolyte imbalance. • Cardiac enzyme measurement can help rule out the occurrence of a myocardial event. • A brain natriuretic peptide test can identify if heart failure is a contributing factor.
