Selecting Patients for Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with heart failure. International guidelines unanimously endorse QRS prolongation to identify candidates for implantation, based on over 4,000 patients randomized in landmark trials. Small, observational, nonrandomized studies with surrogate end points have promoted echocardiography as a superior method of patient selection. Over 30 dyssynchrony parameters have been proposed. Most lack validation in appropriate clinical settings, including demonstration of short- and long-term reproducibility and intra- and interobserver variability. Prospective multicenter trials have proved informative in unexpected ways. In core laboratories, parameters exhibit striking variability, poor reproducibility, and limited predictive power. We are concerned that many centers today are using these techniques to select patients for CRT. Publication density and bias have misinformed clinical decision making. Echocardiographic parameters have no place in denying potentially life-saving treatment or in exposing patients to unnecessary risks and draining health care resources. Such measures should not stray beyond the research environment unless validated in randomized trials with robust clinical end points. The electrocardiogram remains a simple, inexpensive, and reproducible tool that identifies patients likely to benefit from CRT. Patient selection must use the parameter prospectively validated in landmark clinical trials: the QRS duration.