by Rida Laeeq, MD, Mark Pollet, MD, Nadeen Faza, MD, and Yochai Birnbaum, MD
A 62-year-old man with nonischemic cardiomyopathy (left ventricular [LV] ejection fraction, 0.30–0.34) presented for evaluation of weakness. In 2011, he had undergone placement of a D224TRK Consulta® CRT-D (Medtronic, Inc.; Minneapolis, Minn) biventricular implantable cardioverter-defibrillator. The pacemaker, programmed in DDD mode, had a lower rate limit of 60 beats/min (cycle length, 1,000 ms) and an upper limit of 130 beats/min (cycle length, 430 ms), a paced atrioventricular (AV)-delay period of 130 ms, and a sensed AV-delay period of 100 ms. The LV lead threshold was 1.25 V at 0.6 ms and was programmed to deliver 1.75 V at 0.6 ms. The right atrial and right ventricular leads were in standard positions. The electrocardiogram appeared as follows (Fig. 1).
