Response to Coceani: Has CRT Earned a Class I Recommendation?

In his provocative article,1 Dr Coceani raises several important issues about the validity of the class IA indication for cardiac resynchronization therapy (CRT) in current American Heart Association/American College of Cardiology/Heart Rhythm Society2,3 and European Society of Cardiology4,5 guidelines for device-based therapy and heart failure management. Recommendations from these documents include low ejection fraction, prolonged QRS duration, and New York Heart Association functional class III or ambulatory Class IV as criteria for the statement that a CRT device should be considered. Dr Coceani points out that a substantial fraction of patients who received biventricular devices fail to improve clinically and cites data showing that many factors can potentially influence responses to CRT. Factors such as intraventricular mechanical dyssynchrony, lead position, location and extent of myocardial scarring, ventricular anatomy, mitral regurgitation, the type of conduction abnormality, and so forth, have all been shown potentially to influence CRT response. Given these observations, Dr Coceani concludes that a class IA indication is not justified on the basis …