Pacemakers and defibrillators for congestive heart failure.

Although medical therapy is the primary therapy for patients with heart failure, the use of pacemakers to improve cardiac hemodynamics is under investigation. Despite promising initial results, controlled studies have not verified the benefit of application of VDD or DDD pacing to a nonselected population of severely symptomatic congestive heart failure (CHF) patients to simply shorten their atrioventricular (AV) delay. There is increasing interest in pacing the left side of the heart or simultaneously pacing the right and left ventricles. Early studies suggest that these techniques may produce favorable hemodynamic effects in patients with CHF. Controlled, randomized studies are now underway. Further, it has been shown that sudden cardiac death accounts for 50% of deaths in patients with CHF. The value of an implantable cardioverter defibrillator (ICD) in secondary prevention of sudden cardiac death is well established. The use of ICD for primary prevention of sudden cardiac death in patients with CHF is being actively evaluated. Several large multicenter trials are underway, some combined with biventricular pacing, and should provide useful data in the coming years.