Cardiac microcurrent (C-MIC) therapy continues to generate excitement and skepticism in heart failure research. At the Heart Failure Society of America annual meeting, a post hoc analysis of the randomized C-MIC II trial used a blinded core lab to re-evaluate cardiopulmonary exercise tests. The analysis showed improvements in peak metabolic equivalents and percent-predicted peak VO2, and a weight-adjusted peak VO2 gain of 2.70 mL/min/kg, but the absolute peak VO2 difference did not reach statistical significance (P=0.079).
The magnitude of benefit drew sharp comment from discussant John Teerlink, who said he was 'highly skeptical' of the effect size while remaining enthusiastic about advancing the field. Investigator Dragana Kosevic acknowledged the results seemed 'too good to be true' and called for larger randomized studies. The original C-MIC II trial was open-label and enrolled only 65 patients, with CPET data originally site-reported rather than centrally adjudicated.
Separately, early data from the C-MIC III first-in-human study suggest the therapy can be delivered subcutaneously rather than via surgical epicardial implant. In a matched comparison of 10 subcutaneous-implant patients against surgical-implant patients and controls, improvements in LVEF, six-minute walking distance, and quality-of-life scores were comparable. The subcutaneous approach is less invasive, but the sample is tiny and the treated patients had more advanced disease at baseline. The field now awaits C-MIC IV, a sham-controlled crossover trial enrolling 60 patients with both ischemic and non-ischemic heart failure, which will also need to address concerns about interference with existing cardiac devices.