Objectives: We sought to determine the effects of cardiac resynchronization therapy (CRT) in New York Heart Association (NYHA) functional class II heart failure (HF) and NYHA functional class I (American College of Cardiology/American Heart Association stage C) patients with previous HF symptoms.

Background: Cardiac resynchronization therapy improves left ventricular (LV) structure and function and clinical outcomes in NYHA functional class III and IV HF with prolonged QRS.

Methods: Six hundred ten patients with NYHA functional class I or II heart failure with a QRS > or =120 ms and a LV ejection fraction < or =40% received a CRT device (+/-defibrillator) and were randomly assigned to active CRT (CRT-ON; n = 419) or control (CRT-OFF; n = 191) for 12 months. The primary end point was the HF clinical composite response, which scores patients as improved, unchanged, or worsened. The prospectively powered secondary end point was LV end-systolic volume index. Hospitalization for worsening HF was evaluated in a prospective secondary analysis of health care use.

Results: The HF clinical composite response end point, which compared only the percent worsened, indicated 16% worsened in CRT-ON compared with 21% in CRT-OFF (p = 0.10). Patients assigned to CRT-ON experienced a greater improvement in LV end-systolic volume index (-18.4 +/- 29.5 ml/m2 vs. -1.3 +/- 23.4 ml/m2, p < 0.0001) and other measures of LV remodeling. Time-to-first HF hospitalization was significantly delayed in CRT-ON (hazard ratio: 0.47, p = 0.03).

Conclusions: The REVERSE (REsynchronization reVErses Remodeling in Systolic left vEntricular dysfunction) trial demonstrates that CRT, in combination with optimal medical therapy (+/-defibrillator), reduces the risk for heart failure hospitalization and improves ventricular structure and function in NYHA functional class II and NYHA functional class I (American College of Cardiology/American Heart Association stage C) patients with previous HF symptoms. (REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction [REVERSE]; NCT00271154).