Circulation: Heart Failure

Safety, Performance, and Efficacy of Cardiac Contractility Modulation Delivered by the 2-Lead Optimizer Smart System

Charles Jost MD

The FIX-HF-5C2 Study
Phi Wiegn, MD, Rodrigo Chan, MD, Charles Jost, MD, Benjamin R. Saville, PhD, Helen Parise, ScD, David Prutchi, PhD, Peter E. Carson, MD, Angela Stagg, BS, Rochelle L. Goldsmith, PhD, Daniel Burkhoff, MD PhD, Department of Clinical Cardiac Electrophysiology, Dallas VA Medical Center, TX (P.W.). Chan Heart Rhythm Institute, Mesa, AZ (R.C.). Southwest Cardiovascular Associates, Mesa, AZ (C.J.). Berry Consultants, Austin, TX (B.R.S.). Independent Consultant, Las Vegas, NV (H.P.). Impulse Dynamics, Mt. Laurel, New Jersey (D.P.). Department of Medicine, Washington VA Medical Center, DC (P.E.C.). Exercise Physiology Laboratory, Columbia University Medical Center, New York (R.L.G.). Cardiovascular Research Foundation, New York (D.B.).

Abstract Background:
Prior studies of cardiac contractility modulation (CCM) 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 this 2-lead system compared with the 3-lead system.

Methods:
Patients with New York Heart Association III/IVa symptoms despite medical therapy, a left ventricular ejection fraction 25% to 45%, and not eligible for cardiac resynchronization therapy could participate. All subjects received the Optimizer 2-lead implant. The primary end point 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 in New York Heart Association symptoms were a secondary end point. The primary safety end point was a comparison of device-related adverse events between the FIX-HF-5C2 and FIX-HF-5C subjects.

Results:
Sixty subjects, 88% male, 66±9 years old with a left ventricular ejection fraction 24±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 versus 19 583±4998 CCM signals/day, CI of difference [-1228 to 1847]). The change of peak VO2 from baseline to 24 weeks was 1.72 (95% Bayesian credible interval, 1.02 2.42)mL/kg per minute greater in the 2-lead device group versus controls. 83.1% of 2-lead subjects compared with 42.7% of controls experienced ≥ 1 class New York Heart Association symptom improvement (P<0.001). There were decreased Optimizer-related adverse events with the 2-lead system compared with the 3-lead system (0% versus 8%; P=0.03).

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

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