A 53-year-old man is admitted to the hospital with a 4-week history of fatigue and decreased exercise tolerance. Climbing 2 flights of stairs causes significant dyspnea. He has had occasional palpitations for months but no chest pain. Medical history is unremarkable, and a routine checkup 6 months ago was normal. The patient had 2 binge-drinking episodes last month but usually drinks only in moderation. He does not routinely take any medications. Blood pressure is 150/90 mm Hg and pulse is 130/min and irregular. Lungs are clear on auscultation. ECG shows no clear P waves. Echocardiography shows left atrial dilation, left ventricular dilation with global hypokinesis and an ejection fraction of 35%, and moderate central mitral regurgitation. Which of the following interventions is most likely to restore left ventricular function in this patient?

Question

A 53-year-old man is admitted to the hospital with a 4-week history of fatigue and decreased exercise tolerance.  Climbing 2 flights of stairs causes significant dyspnea.  He has had occasional palpitations for months but no chest pain.  Medical history is unremarkable, and a routine checkup 6 months ago was normal.  The patient had 2 binge-drinking episodes last month but usually drinks only in moderation.  He does not routinely take any medications.  Blood pressure is 150/90 mm Hg and pulse is 130/min and irregular.  Lungs are clear on auscultation.  ECG shows no clear P waves.  Echocardiography shows left atrial dilation, left ventricular dilation with global hypokinesis and an ejection fraction of 35%, and moderate central mitral regurgitation.  Which of the following interventions is most likely to restore left ventricular function in this patient?

Quizplus · Accepted Answer

This patient with a several-week history of dyspnea and fatigue has a rapid and irregular pulse with ECG showing no clear P waves, consistent with atrial fibrillation with rapid ventricular response (ie, rate >100/min). His history of palpitations suggests the atrial fibrillation has been occurring for months. An elevation in ventricular contraction rate (eg, >100/min) sustained for weeks or more often causes left ventricular (LV) dilation and cardiomyocyte dysfunction; this is known as tachycardia-induced cardiomyopathy and is the most likely cause of the LV dysfunction in this patient. The LV dysfunction in tachycardia-induced cardiomyopathy is usually reversible with slowing of the ventricular contraction rate, which can be accomplished with either improved rate control or reestablishment of sinus rhythm (ie, rhythm control). The prevention of tachycardia-induced cardiomyopathy is one of the primary objectives of adequate rate or rhythm control of atrial fibrillation. rate or rhythm control (Choice A) Coronary artery revascularization can lead to significant improvement in LV function in patients with ischemic heart disease. However, ischemic heart disease more commonly causes segmental (rather than global) hypokinesis, and this patient's normal checkup 6 months ago is more suggestive of new-onset atrial fibrillation leading to LV dysfunction due to sustained tachycardia. (Choices B, C, and D) Reductions in preload (eg, with diuretics or venous vasodilators) and afterload (eg, with arterial vasodilators) reduce cardiac work and can improve LV function in patients with systolic dysfunction. Inotropic agents (eg, digoxin) can also improve LV function via an increase in cardiac contractility. However, all these interventions are used for symptomatic management of LV systolic dysfunction. Tachycardia-induced cardiomyopathy is usually reversible with reduced heart rate; therefore, reducing this patient's heart rate via rate or rhythm control is most appropriate. (Choice F) Mitral valve repair is indicated for patients with LV systolic dysfunction in the setting of severe primary mitral regurgitation (ie, from a defect within the valve itself). This patient's mitral regurgitation is only moderate and most likely secondary to LV dilation; therefore, surgery is unlikely to be helpful. secondary Educational objective: An elevation in ventricular contraction rate (eg, >100/min) that is sustained for weeks or more can cause left ventricular dilation and cardiomyocyte dysfunction known as tachycardia-induced cardiomyopathy. The cardiomyopathy is usually reversible with slowing of the ventricular contraction rate; in atrial fibrillation this is accomplished via improved rate control or reestablishment of sinus rhythm (ie, rhythm control). 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)

A 53-Year-Old Man Is Admitted to the Hospital with a 4-Week