Impact of ejection fraction on the clinical response to cardiac resynchronization therapy in mild heart failure.

Background: Current guidelines recommend cardiac resynchronization therapy (CRT) in mild heart failure (HF) patients with QRS prolongation and ejection fraction (EF) ≤30%. To assess the effect of CRT in less severe systolic dysfunction, outcomes in the REsynchronization reVErses Remodeling in Systolic left vEntricular dysfunction (REVERSE) study were evaluated in which patients with left ventricular (LV) ejection fraction (LVEF) >30% were included.
Methods and Results: The results of patients with baseline EF >30% (n=177) and those with EF ≤30% (n=431), as determined by a blinded core laboratory, were compared. In the LVEF >30% subgroup, there was a trend for improvement in the clinical composite response with CRT ON versus CRT OFF (P=0.06) and significant reductions in LV end systolic volume index (-6.7 ± 21.1 versus 2.1 ± 17.6 mL/m(2); P=0.01) and LV mass (-20.6 ± 50.5 versus 5.0 ± 42.4 g; P=0.04) after 12 months. The time to death or first HF hospitalization was significantly prolonged with CRT (hazard ratio, 0.26; P=0.012). In the LVEF <30% subgroup, significant improvements in clinical composite response (P=0.02), reverse remodeling parameters, and time to death or first HF hospitalization (hazard ratio, 0.58; P=0.047) were observed. After adjusting for important covariates, the CRT ON assignment remained independently associated with improved time to death or first HF hospitalization (hazard ratio, 0.54; P=0.035), whereas there was no significant interaction with LVEF.
Conclusions: Among subjects with mild HF, QRS prolongation, and LVEF >30%, CRT produced reverse remodeling and similar clinical benefit compared with subjects with more severe LV systolic dysfunction.
Clinical Trial Registration- Url: http://www.clinicaltrials.gov. Unique identifier: NCT00271154.