Don't Rush to Implant a Dual-Chamber ICD

Studies showing that implantable cardioverter-defibrillators (ICDs) effectively prevent sudden cardiac death in high-risk patients have been conducted mostly on single-chamber ICDs programmed to provide backup ventricular pacing, typically at 40 bpm (VVI-40). Cardiologists have assumed that ICDs with dual-chamber pacing benefit patients by allowing optimization of pharmacologic therapy for heart failure, by limiting supraventricular arrhythmias, and by optimizing resting and exercise heart rates. This manufacturer-supported, single-blind study challenges that assumption.

Dual-chamber ICDs with backup VVI-pacing capacity were implanted in 506 patients (mean age, 65) who had standard indications for ICD therapy and did not have indications for…