Case #2 - Evaluation of Suspected Device Malfunction on ECG

by Luke Cunningham, MD, Henry D. Huang, MD, and Yochai Birnbaum, MD

A 62-year-old man with nonischemic cardiomyopathy, a history of Boston Scientific biventricular implantable cardioverter-defibrillator placement (in 2011), ventricular tachycardia after radiofrequency ablation (April and November 2014), paroxysmal atrial fibrillation, and severe mitral regurgitation presented with acute exacerbation of heart failure. A resting electrocardiogram (ECG) showed normal sequential atrioventricular (AV) pacing at a heart rate of 63 beats/min. Baseline device settings were DDD with a lower rate of 60 beats/min, an upper rate of 115 beats/min, a minimum sensed AV delay of 135 ms, and a minimum paced AV delay of 180 ms. The patient underwent mitral valve replacement. Three days later, the pacemaker rate was increased to 80 beats/min, and an ECG showed pacing concomitantly within the T wave in beats 5 and 13 of the rhythm strip (Fig. 1).