A 42-year-old man comes to the office due to fatigue and shortness of breath. His symptoms began 6 months ago with decreased exercise tolerance during his typical morning jog. Since then, his fatigue has gradually progressed and he has also had occasional palpitations, which he describes as his "heart races fast." The patient reports a weight gain of 5 kg (11 lb) over the last month and has had shortness of breath with mild exertion and leg swelling for the past 2 weeks. The patient does not remember any recent viral illness and has no prior medical conditions. He takes no medications, is a lifelong nonsmoker, and drinks alcohol occasionally. Family history is unremarkable. Temperature is 37.2 C (99 F), blood pressure is 122/80 mm Hg, pulse is 135/min and irregular, and respirations are 18/min. Jugular venous pressure is 12 cm H₂O. Lung examination reveals decreased breath sounds at the bases with occasional bibasilar crackles. Cardiac examination reveals a 2/6 holosystolic murmur best heard at the apex. There is 2+ bilateral lower extremity pitting edema. Blood cell counts, serum chemistry, and TSH are within normal limits. ECG is shown in the exhibit. Echocardiography shows a dilated and diffusely hypokinetic left ventricle with an ejection fraction of 25%. The right ventricle is mildly hypokinetic. The left atrium is mildly dilated. There is a central jet of moderate mitral regurgitation. Which of the following is most likely to provide the greatest long-term improvement in this patient's left ventricular function?

Question

Quizplus · Accepted Answer

This patient's presentation (6 months of fatigue and palpitations preceding more recent symptoms of decompensated heart failure) is most consistent with tachycardia-induced cardiomyopathy due to atrial fibrillation with rapid ventricular response. Chronic tachycardia, typically >120 bpm for a period of weeks or months, can lead to myocardial cellular changes, left ventricular (LV) dilation, and impaired LV function. Other arrhythmias that have been implicated include atrial flutter, multifocal atrial tachycardia, reentrant supraventricular tachycardia, ventricular tachycardia, and, in rare cases, frequent premature ventricular contractions. Patients typically present with palpitations or symptoms of decompensated heart failure. Diagnostic evaluation in such patients should include ECG or ambulatory Holter monitoring to document arrhythmia episodes, echocardiogram to assess LV function, and testing to rule out myocardial ischemia. Depending on the etiology of the tachycardia, therapy involves restoring normal sinus rhythm or aggressive control of rapid ventricular rate (eg, with beta blockers). Adequate heart rate control often results in significant or complete recovery of LV function over a period of months. (Choice A) Afterload reduction is important for patients with cardiomyopathy due to prolonged systemic hypertension; however, this patient is currently normotensive, making hypertension-induced cardiomyopathy less likely. (Choice B) Anti-ischemic therapy (eg, coronary artery revascularization) can lead to significant improvement in LV function in patients with left main or multivessel coronary artery disease. However, ischemic cardiomyopathy is less likely in this relatively young man without significant coronary artery disease risk factors. (Choice C) Diuresis and fluid optimization are important in the management of cardiomyopathy and decompensated heart failure. Although diuresis often results in some improvement in LV function, marked improvement is not typical. Adequate heart rate control may result in complete normalization of LV function in this patient. (Choice E) Mitral regurgitation (MR) with a central (rather than eccentric) regurgitation jet is consistent with secondary MR due to mitral annulus dilation in the setting of dilated cardiomyopathy (functional MR). Mitral valve surgery is generally not helpful for secondary MR as the valve cusps are intrinsically normal. Medical therapy for dilated cardiomyopathy is most appropriate. Educational objective: Tachycardia-induced cardiomyopathy can develop in patients with persistent tachyarrhythmias and prolonged periods of rapid ventricular rate. Treatment in such patients is aimed at restoration of sinus rhythm or aggressive control of ventricular rate, which often leads to significant or complete recovery of left ventricular function. __________ References: Left ventricular dysfunction due to atrial fibrillation in patients initially believed to have idiopathic dilated cardiomyopathy. (http://www.ncbi.nlm.nih.gov/pubmed/1598871) Tachycardia-induced heart failure. (http://www.ncbi.nlm.nih.gov/pubmed/21461112) 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines (http://www.ncbi.nlm.nih.gov/pubmed/33332149)

A 42-Year-Old Man Comes to the Office Due to Fatigue