Cardiac Resynchronization for Heart Failure

Cardiac conduction abnormalities may worsen heart failure by disrupting the coordination of left ventricular contraction, making it even less effective. This pathophysiologic insight suggests that judiciously applied electrical stimuli could improve the coordination and efficiency of left ventricular contraction (1). The clinical value of this new approach, called cardiac resynchronization therapy (CRT), has been evaluated in several randomized, controlled clinical trials. This evidence is summarized in a systematic review by McAlister and associates in this issue (2), which also contains a companion article by Nichol and coworkers (3) analyzing the cost-effectiveness of using CRT in patients with heart failure.

Randomized trials are essential tests of the effect of therapy on clinical outcomes, but trials of implanted devices are particularly challenging. Most of the studies of CRT have been small, which limits the conclusions that can be drawn. Another challenge is that the technology is rapidly evolving. Current CRT devices are combined with an implantable cardioverter defibrillator (ICD), but only a few trials with limited outcome data have directly tested the value of adding CRT capability to an ICD. The evidence about use of CRT in heart failure is therefore relatively thin, especially in comparison with the solid evidence about pharmacologic treatments such as angiotensin-converting enzyme inhibitors and β-blockers.

Two major goals of heart failure treatment are to improve either the length or quality of the patient's life. As reviewed …