The C-MIC II follow-up study: safety and efficacy results 12 months after deactivation of cardiac microcurrent therapy

Abstract
Aims:
The C-MIC II trial demonstrated benefits of 6 months of cardiac microcurrent (C-MIC) therapy in patients with nonischaemic heart failure with reduced ejection fraction (HFrEF). The prospective C-MIC II follow-up study evaluates safety and efficacy outcomes post-device deactivation.

Methods
Primary safety-related endpoints included all-cause, cardiovascular and device-related mortality, hospitalizations, and adverse events (AEs). Secondary efficacy-related endpoints included changes in left ventricular ejection fraction (LVEF), Kansas City Cardiomyopathy Questionnaire Overall Summary Score (KCCQ-OSS), 6-min walk distance (6MWD), New York Heart Association (NYHA) class, and device reactivation rate. Here, we report 12-month results comparing the 6-month time point (at the end of active therapy) with the 18-month time point (12 months post-deactivation).

Results
Of 32 eligible patients, 31 (97%) were enrolled. At 12 months post-device deactivation, 3 patients (10%) were hospitalized and 1 died (3%); none were device-related. One device-related AE occurred and was resolved completely. Improvements in LVEF [vs pre-implantation: +6%; 95% confidence interval (CI) 5–8; P < .0001] and KCCQ-OSS (vs pre-implantation: +43 points; 95% CI 36–49; P < .0001) were sustained and unchanged from 6 months (LVEF: −0.1%; 95% CI −2 to 2; P = .87; KCCQ-OSS: −2; 95% CI −8 to 4; P = .49). The 6MWD remained improved (vs pre-implantation: +150 m; 95% CI 109–191; P < .0001), with a modest decrease (−31 m; 95% CI −56– to −7; P = .013) from 6 months. Improvements in NYHA class (≥1-class improvement in 77% patients) were sustained. Three (10%) patients required device reactivation.

Conclusion
Among patients previously treated with C-MIC device, improvements in LVEF, 6MWD, NYHA class, and KCCQ-OSS were sustained, with a favourable safety profile 12 months post-deactivation.