A 72-year-old man comes to the office due to palpitations and mild fatigue for the last 3 weeks. He has otherwise been feeling well. The patient walks 2 miles around his neighborhood twice per week with no chest pain or shortness of breath. Medical history is remarkable for benign prostatic hyperplasia, for which he takes terazosin. He drinks 1-2 cups of coffee every day and a glass of wine once or twice per month. Temperature is 37 C (98.6 F), blood pressure is 128/68 mm Hg, and pulse is 78/min and irregular. Physical examination reveals a 2/6 early-peaking systolic murmur at the right upper sternal border. Carotid pulses are prompt and full bilaterally. The lungs are clear to auscultation. There is no peripheral edema. ECG is shown in the exhibit. Which of the following is most likely the strongest risk factor for this patient's presentation?
Atrial fibrillation | |
Pathogenesis |
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Clinical |
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Diagnosis |
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HTN = hypertension; MS = mitral stenosis. | |
This patient with several weeks of palpitations and fatigue has atrial fibrillation, which is recognized on ECG by an irregularly irregular rhythm (irregular R-R intervals) and an absence of organized P waves. Atrial fibrillation usually occurs in the setting of atrial remodeling, which describes changes to the atrial myocardium that result from both normal aging and underlying comorbidities that cause atrial dilation (eg, hypertension, heart failure, mitral valve disease). Coronary artery disease and its associated risk factors (eg, diabetes mellitus, smoking) are also associated with atrial fibrillation, although their contribution may be primarily driven by ischemia that leads to left ventricular dysfunction and consequent left atrial dilation.
Age, independent of comorbidities, is one of the strongest risk factors for atrial fibrillation. Atrial fibrillation is relatively rare in those age <40, but the prevalence is estimated at approximately 10% in those age >75 and approaches 20% in those age >85.
(Choices B and D) After remodeling has created a susceptible substrate, certain triggers (eg, increased sympathetic drive) can initiate atrial fibrillation. Heavy alcohol use (eg, large binges or chronic ingestion of >1-2 drinks per day) is one such trigger, but occasional alcohol intake is unlikely to significantly contribute. High caffeine intake (eg, coffee) may somewhat encourage the triggering of atrial fibrillation (via increased sympathetic stimulation), but there is little evidence to support this association.
(Choice C) This patient's early peaking systolic murmur at the right upper sternal border with prompt and full carotid pulses is consistent with mild aortic stenosis. Both mitral regurgitation and especially mitral stenosis are strongly associated with atrial fibrillation as these valvular defects can cause left atrial dilation even in the absence of heart failure. However, aortic stenosis typically must be severe to cause left atrial dilation; mild aortic stenosis is not associated with atrial fibrillation.
(Choice E) Beta adrenergic agonists (eg, albuterol) may sometimes trigger atrial fibrillation by stimulating the generation of ectopic conduction foci. However, terazosin is an alpha blocker and does not significantly affect cardiac conduction.
Educational objective:
Age, independent of comorbidities, is one of the strongest risk factors for atrial fibrillation as age-related change to the atrial myocardium is one of the primary contributors to atrial remodeling. Left atrial dilation is the other primary contributor to atrial remodeling; therefore, comorbidities that cause left atrial dilation (eg, hypertension, heart failure, mitral valve disease) are also strongly associated with atrial fibrillation.