Cardiac Resynchronization Therapy to Prevent Heart Failure: Gathering Momentum

According to American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines, cardiac resynchronization therapy (CRT) is a Class I indication in individuals with NYHA class III or IV heart failure and prolonged QRS duration. Whether the benefit of CRT extends to NYHA class II patients is less clear, and the data on NYHA class I patients are limited to findings from a short-term study showing improvements in LV remodeling (JW Cardiol Oct 29 2008). Long-awaited findings from the international MADIT-CRT trial addressing the use of CRT in patients with NYHA class I and II heart failure are now available.

From December 22, 2004, through April 23, 2008, researchers enrolled 1820 patients with QRS durations of ≥130 milliseconds, LV ejection fractions of ≤30%, and either ischemic cardiomyopathy and NYHA class I or II symptoms or nonischemic cardiomyopathy and NYHA class II symptoms. The participants were randomized in a 3:2 ratio to receive an implantable cardioverter-defibrillator with or without CRT. In June 2009 the trial was halted early because of demonstrated superiority of CRT-ICD.

During an average follow-up of 2.4 years, the primary composite endpoint of acute congestive heart failure and all-cause mortality occurred in 187 of 1089 patients in the CRT-ICD group (17.2%) and in 185 of 731 patients in the ICD-only group (25.3%). Because mortality was low, this result was driven by the reduction in heart failure events. In addition, LVEF improved more in CRT-ICD patients than in ICD-only patients (11% vs. 3%). The benefits did not differ between the ischemic and nonischemic cardiomyopathy subgroups.