Keys to successful cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) improves functional status in selected groups of patients with heart failure and has achieved widespread use. However, approximately one-third of patients fail to benefit from CRT. Many of these failures can be attributed to improper patient selection, suboptimal left ventricular lead placement and device programming and inadequate medical therapy. This article addresses these issues and proposes an approach to improving the results of CRT.