Who Should Receive the Subcutaneous Implanted Defibrillator?

The evolution of implantable cardioverter defibrillator (ICD) technology for the past 3 decades has been nothing short of explosive, incorporating progressively transvenous leads, multizone programming, dual chamber antibradycardia pacing, antitachycardia pacing (ATP), sophisticated single- and dual-chamber discrimination algorithms, cardiac resynchronization therapy (CRT), and programmable options numbering into the thousands. As a consequence, ICDs have been used to treat patients with a variety of clinical needs, including those with a known history of ventricular tachycardia (VT), survivors of out of hospital cardiac arrest, patients with requirements for pacing or resynchronization with concomitant indications for an ICD, and patients who do not fit within these categories but are at risk for sudden cardiac death (SCD).Response by Rav Acha and Milan on p 1244Typically, the efficacy of most cardiac therapies is assessed initially on the sickest patients or those at highest risk. Such was the case for the ICD that was initially approved only for patients who had survived cardiac arrest. These early systems had epicardial leads and no pacing capabilities. Subsequently, transvenous lead systems and other advances were made in ICD technology, as noted above. However, these devices were approved and used based on the demonstration of the ability to detect and to terminate VT and ventricular fibrillation (VF). In fact, more complex therapies are not always better for patient outcomes. The Dual Chamber and VVI Implantable Defibrillator (DAVID) trial showed that indiscriminate right ventricular pacing is associated with increased risk of heart failure hospitalization and death, and more recent analyses continue to question the overuse of dual chamber devices.1,2 Similarly, CRT may be associated with more heart failure hospitalization among patients without QRS prolongation.3The landmark prospective randomized trials showed a mortality benefit of ICDs for both primary and secondary prevention of SCD. The early …