Indications for cardiac resynchronization therapy: should they be extended?

Cardiac resynchronization therapy (CRT) has been shown to improve symptoms and quality of life of patients suffering from systolic heart failure refractory to medical therapy. It also induces a positive left ventricular remodelling process during long-term follow-up. However, based on classical indications for CRT, only a minority of patients with heart failure will benefit from this therapy and approximately one-third of patients implanted will not improve. There is a need for better methods with which to identify potential responders to CRT more accurately. Such methods might enable the identification of patients with a right bundle branch block pattern or standard pacing indications who could benefit from CRT. Better identification methods might also help to avoid heart failure progression in less symptomatic patients with a depressed left ventricular ejection fraction. (C) 2003 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.