Cardiac resynchronization therapy using a pacemaker or a defibrillator: Patient selection and evidence to support it.

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure (HF), myocardial dysfunction and prolonged ventricular depolarization on surface electrocardiogram. CRT can be delivered by a pacemaker (CRT-P) or a combined pacemaker-defibrillator (CRT-D). Although these two types of devices are very different in size, function, and cost, current published guidelines do not distinguish between them, leaving the choice of which device to implant to the treating physician and the informed patient. In this paper, we review the published CRT clinical trial literature with focus on the outcomes of HF patients treated with CRT-P versus CRT-D. We also attempt to provide guidance as to the appropriate choice of CRT device type, in the absence of randomized prospective trials geared to answer this specific question.