ECG response: May 6, 2014.

Abstract

ECG Challenge: A 76-year-old man with a nonischemic cardiomyopathy is admitted to the hospital because of progressive weight gain and worsening peripheral edema. He notes that he has gained 12 pounds over the past 2 weeks. He states that he has been compliant with all of his medications, but does admit to dietary indiscretion. ECG A shows that the first 5 QRS complexes are regular at a rate of 48 bpm. There is a P wave before each of these QRS complexes (+) with a stable PR interval (0.24 s). The P wave is positive in leads I, II, aVF, and V4 to V6. Hence, this is a sinus bradycardia with a first-degree atrioventricular (AV) block or prolonged AV conduction. The QRS complex duration is increased, but there is a beat-to-beat variation in the width (ie, 0.12 and 0.14 s). The wider QRS complex has a typical right bundle branch block morphology with an RSR′ in lead V1 (→) and a broad …