Safety, Performance and Efficacy of Cardiac Contractility Modulation Delivered by the 2-Lead Optimizer Smart System: The FIX-HF-5C2 Study

Introduction:  Prior studies of CCM^TM employed a 3-lead Optimizer® System.  A new 2-lead system eliminated the need for an atrial lead. This study tested the safety and effectiveness of the 2-lead system compared to the 3-lead system.   

Methods:  Patients with New York Heart Association (NYHA) III/IVa symptoms despite medical therapy, left ventricular ejection fraction (LVEF) 25-45%, not eligible for CRT could participate.  All subjects received an Optimizer 2-lead implant. The primary endpoint was the estimated difference in the change of peak VO₂ from baseline to 24 weeks between FIX-HF-5C2 (2-lead system) subjects relative to control subjects from the prior FIX-HF-5C (3-lead system) study.  Changes of NYHA were a secondary endpoint. The primary safety endpoint was a comparison of device-related adverse events between FIX-HF-5C2 and FIX-HF-5C subjects. 

Results: 60 subjects, 88% male, 66±9 years old with LVEF 34±6% were included. Baseline characteristics were similar between FIX-HF-5C and FIX-HF-5C2 subjects except that 15% of FIX-HF-5C2 subjects had permanent atrial fibrillation versus 0% in FIX-HF-5C.  CCM delivery did not differ significantly between 2- and 3-lead systems (19,892±3472 vs. 19,583±4998 CCM signals/day, CI of difference [-12228,1847]).  Change of peak VO₂ from baseline to 24 weeks was 1.72 (95% Bayesian credible interval [BCI]:1.02,2.42) ml/kg/min greater in the 2-lead device group versus controls.  83.1% of 2-lead subjects compared to 42.7% of controls experienced ≥1 class NYHA improvement (p<0.001).  There were decreased Optimizer-related adverse events with the 2- lead compared to the 3-lead system (0% vs. 8%, p=0.03).

Conclusions:  The 2-lead system effectively delivers comparable amount of CCM signals (including in subjects with atrial fibrillation) as the 3-lead system, is equally safe and improves peak VO₂ and NYHA. Device-related adverse effects are less with the 2-lead system.

Tags: Cardiac Contractility Modulation, CCM, CPX