Observational Study Lends Support To CRT Guidelines

A large observational study published in JAMA suggests that patients with left bundle-branch block (LBBB) and longer QRS duration derive the most benefit from a cardiac resynchronization therapy defibrillator (CRT-D). The findings appear to support current, but often criticized, guidelines from the American College of Cardiology, American Heart Association, and the Heart Rhythm Society, in which a class I recommendation is restricted to patients with LBBB and QRS duration of 150 ms or greater.