A 63-year-old man comes to the office due to shortness of breath on mild exertion over the last 6 months. He has no chest pain, syncope, palpitations, or weight loss. The patient has ischemic cardiomyopathy, and he underwent coronary artery bypass grafting a year ago. He is receiving guideline-based optimal pharmacotherapy for heart failure. He appears comfortable at rest with no significant respiratory distress. Blood pressure is 122/80 mm Hg and pulse is 62/min and regular. Oxygen saturation is 96% on room air. S3 is heard at the apex. Scattered bibasilar crackles are heard at the lung bases. Abdominal examination is unremarkable. There is 1+ lower extremity edema bilaterally. Laboratory results are as follows: Transthoracic echocardiography shows left ventricular dilation with a left ventricular ejection fraction of 25%. Which of the following ECG findings would be an indication for further management in this patient?

Question

A 63-year-old man comes to the office due to shortness of breath on mild exertion over the last 6 months.  He has no chest pain, syncope, palpitations, or weight loss.  The patient has ischemic cardiomyopathy, and he underwent coronary artery bypass grafting a year ago.  He is receiving guideline-based optimal pharmacotherapy for heart failure.  He appears comfortable at rest with no significant respiratory distress.  Blood pressure is 122/80 mm Hg and pulse is 62/min and regular.  Oxygen saturation is 96% on room air.  S3 is heard at the apex.  Scattered bibasilar crackles are heard at the lung bases.  Abdominal examination is unremarkable.  There is 1+ lower extremity edema bilaterally.  Laboratory results are as follows:  Transthoracic echocardiography shows left ventricular dilation with a left ventricular ejection fraction of 25%.  Which of the following ECG findings would be an indication for further management in this patient?

Quizplus · Accepted Answer

Explanation: This patient has ischemic cardiomyopathy with severe left ventricular (LV) systolic dysfunction and is on optimal medical therapy. Nonetheless, he continues to have New York Heart Association (NYHA) class III heart failure symptoms. Abnormal ventricular conduction in severe heart failure can impair ventricular synchrony and adversely affect cardiac function. In selected patients, cardiac resynchronization therapy with simultaneous pacing of the right and left ventricles (biventricular pacing) has been shown to improve exercise tolerance and NYHA functional class, and reduce the rates of recurrent hospitalization and overall mortality. class III Current guidelines recommend biventricular pacing devices for patients in sinus rhythm who meet all of the following criteria: LV ejection fraction <35% NYHA class II, III, or IV heart failure symptoms (ie, the presence of any symptoms) Left bundle branch block with QRS duration >150 msec. Many of these patients also meet criteria for an implantable cardioverter-defibrillator (ICD) to prevent sudden cardiac death and can undergo combination ICD and biventricular pacemaker placement. criteria (Choice A) Deep Q waves in leads V1-V4 are consistent with previous anterior myocardial infarction. This patient has ischemic cardiomyopathy with previous coronary artery bypass grafting; anterior Q waves on ECG are not unexpected and would not alter further management. (Choice B) First-degree atrioventricular block (PR interval >200 msec) represents delayed conduction from the sinoatrial node to the ventricles. Patients with marked prolongation of the PR interval (eg, >300 msec) may rarely develop symptoms, but otherwise the condition is benign with minimal effect on cardiac function and requires no intervention. (Choice C) Left axis deviation is often present in patients with LV hypertrophy; such a finding on ECG would not alter management in a patient with severe LV dysfunction. (Choice E) A prolonged corrected QT interval (QTc) of 480 msec warrants monitoring but would not significantly affect management in this patient, who is not taking medications known to significantly prolong the QTc (eg, dofetilide, haloperidol) and who does not have hypokalemia or hypomagnesemia. Educational objective: Cardiac resynchronization therapy with a biventricular pacing device is recommended in patients in sinus rhythm with the combination of symptomatic heart failure, left ventricular ejection fraction <35%, and left bundle branch block with QRS duration >150 msec. References: Impact of QRS duration on clinical event reduction with cardiac resynchronization therapy: meta-analysis of randomized controlled trials. (http://www.ncbi.nlm.nih.gov/pubmed/21670335) 2012 ACCF/AHA/HRS focused update of the 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. (http://www.ncbi.nlm.nih.gov/pubmed/22965336) 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/23741058)

A 63-Year-Old Man Comes to the Office Due to Shortness