Cardiac contractility modulation in HFrEF patients with QRS duration 120-149 ms: reduction in heart failure hospitalizations and improvement in functional outcome.

Background: A subset of heart failure (HF) patients qualifies for cardiac resynchronization therapy (CRT). However, a 30% CRT non-responder rate persists, with patients with narrower QRS durations (i.e., QRSd 120-149 ms) receiving less or inconsistent benefit. CCM may be an important alternative therapy option but has largely been evaluated only in HF patients with QRSd <120 ms.

Objectives: Primarily to evaluate the impact of cardiac contractility modulation (CCM) on HF-related hospitalizations and secondarily on left ventricular EF (LVEF) as well as quality of life in HF patients with QRSd 120-149 ms, compared to QRSd <120 ms.

Methods: CCM-REG enrolled 503 HF patients with a follow-up of up to 2 yrs. Hospitalization rates were available for 1 yr pre-implant. Safety was assessed by comparison of actual versus MAGGIC score- or SHFM-predicted mortality.

Results: Among 111/455 subjects with QRSd 120-149 ms (mean QRSd 130±8 ms, age 68±10 yrs, 20% female, LVEF 29±9%, 82% NYHA class III), CCM diminished HF-related hospitalization rate by 72% (pre- vs. post-implant 0.90 vs. 0.25 events/per patient-yr over 2 yrs; p<0.001). LVEF improved by 7±8% (p=0.01 vs. baseline), MLWHFQ score by 10±23 pts (p=0.01 vs. baseline), and NYHA class by 0.5±0.7 classes (<0.001 vs. baseline). The effect size was similar to that in the QRSd <120 ms patients. Mortality within first year was 19% in QRSd 120-149 ms patients, i.e., not significantly different from the MAGGIC score or SHFM prediction.

Conclusions: CCM significantly improved HF control in NYHA III HFrEF patients with moderately prolonged QRSd 120-149 ms. The effect was similar to patients with QRSd <120ms.