Clinical effects of cardiac contractility modulation in heart failure with mildly reduced systolic function

AIMS: Increasing attention is being given to patients with heart failure and ‘mid‐range’ left ventricular ejection fraction (LVEF, ≥40% and <50%) for whom there are no approved therapies that improve prognosis. We aim to assess for the first time the effects of cardiac contractility modulation (CCM) therapy in this patient population. METHODS AND RESULTS: We assessed the effects of 6‐ month CCM therapy on functional status, exercise tolerance and quality of life in a subgroup of 53 patients with a LVEF of 40–45% recruited in previous CCM studies, including 37 patients in the CCM group and 16 in the control group. New York Heart Association classification improved by ≥1 class from baseline to 24 weeks in 80.6% (95% confidence interval [62.5%, 92.5%]) of patients in the CCM group compared with 57.1% in the control group (95% confidence interval [28.9%, 82.3%], P = 0.15). Six‐minute walk distance increased significantly in the CCM group with a net between‐group treatment effect of 53.9 ± 74.2 m (P = 0.05). Peak VO(2) improved in the CCM group with a net between‐group treatment effect of 2.0 ± 2.8 mL/kg/min (P = 0.02). Minnesota Living with Heart Failure Questionnaire score decreased from baseline to 24 weeks with a net between‐group treatment effect of −13.1 ± 21.0 (P = 0.10). There were no significant differences in the adverse event rate between the CCM and control groups. CONCLUSIONS: These preliminary results suggest that CCM exerts favourable effects on exercise tolerance and quality of life in patients with LVEF in the range of 40–45% with an acceptable safety profile. Further randomized controlled studies are planned to prove these effects.