Cardiac Microcurrent Therapy Raises Eyebrows In Heart Failure

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Presentations at the Heart Failure Society of America meeting reported further early findings for cardiac microcurrent therapy, including a post hoc exercise-test analysis and initial results with a subcutaneous implant. Researchers and a trial discussant stressed that the small, early studies cannot establish the treatment’s effectiveness or safety; a 60-person sham-controlled trial is planned.

Researchers presenting at the Heart Failure Society of America annual meeting reported additional early findings for cardiac microcurrent therapy, or C-MIC, including a reanalysis of exercise-test results and preliminary experience with a subcutaneous implant. The findings drew interest but also skepticism over the size of the reported benefits; the studies remain too small to establish whether the device works or how safely it can be used.

In a post hoc analysis of the randomized C-MIC II trial, investigators reassessed six-month cardiopulmonary exercise test results using a blinded core laboratory. Among 42 participants in the reanalysis, reported changes favored C-MIC over non-implanted controls in peak metabolic equivalents and percent-predicted peak oxygen uptake. The differences in those measures were statistically significant, with P values of 0.021. The reported difference in absolute peak VO2 was 208.7 versus 7.3 mL/min, but did not meet the conventional threshold for statistical significance (P=0.079).

Dragana Kosevic, MD, of Cardiovascular Institute Dedinje in Belgrade, reported a 2.70 mL/min/kg increase in weight-adjusted peak VO2 for the C-MIC group. She said the core-lab results supported functional benefits, while calling for larger randomized studies. The reanalysis addressed a limitation of the original trial, which used exercise-test values reported by study sites rather than central adjudication. However, only five of seven sites contributed to the reanalysis.

Stefan Simovic, MD, of the University of Kragujevac presented preliminary evidence on a subcutaneous version of the device. His group compared 10 first-in-human C-MIC III participants with matched patients from C-MIC II and controls from that earlier trial. The presentation reported comparable improvements in ejection fraction, six-minute walking distance and quality-of-life scores for the subcutaneous group. The comparison was small and non-randomized; the C-MIC III participants also had more advanced heart disease at baseline.

A Less Invasive Device, Still Unproven

The move from an epicardial implant requiring surgery to a subcutaneous system could make the procedure more accessible if further trials show it is effective and safe. The early reports address both a potential treatment option for people with heart failure and the practical question of whether the device can be implanted using a less invasive approach.

But the reported changes should not be read as proof of clinical benefit. The C-MIC II analysis involved a small subset of participants, and the subcutaneous evidence came from just 10 first-in-human recipients compared with matched groups rather than a randomized test. Heart failure patients and clinicians therefore lack reliable evidence from these presentations about whether C-MIC improves outcomes over time, or which patients might benefit.

From Epicardial Implant to C-MIC III

C-MIC is being developed to address changes in the heart’s electrical fields associated with myocardial edema and impaired left-ventricular function. The proposed mechanism is that microcurrents may shift activated fibroblasts toward a less fibrogenic state, potentially reducing stiffness and changing heart structure and function. This remains a proposed explanation, not a demonstrated mechanism of clinical benefit.

The earlier C-MIC II trial randomized 65 people with refractory, non-ischemic heart failure with reduced ejection fraction. It reported improvements in ejection fraction, symptoms, functional capacity and quality of life at six months compared with controls, while peak VO2 only trended toward benefit in the original analysis. The newer core-lab reanalysis revisited the exercise-test data. C-MIC III then began testing a subcutaneous approach in a small first-in-human study, with earlier six-month results reported as improvements from baseline in ejection fraction, walking distance and quality of life.

“I am highly skeptical of the magnitude of the benefit that you folks are showing, but I remain actually very enthusiastic about moving this forward.”

— John Teerlink, MD, of the San Francisco VA and UCSF Medical Center

Benefit and Device Risks Remain Open

The presentations do not settle whether C-MIC improves heart-failure outcomes. C-MIC II was small and open-label, the exercise-test reanalysis included 42 people, and the subcutaneous comparison included only 10 recipients. The matched groups also differed in disease severity at baseline, limiting how confidently their results can be compared. It is not clear whether the early changes will persist or translate into fewer hospitalizations, longer survival or sustained improvements in daily life.

Safety and device interactions also need further study. Teerlink raised questions about people with existing implanted devices, including defibrillators and cardiac resynchronization systems, as well as other heart-failure devices and coronary stents. The meeting report does not provide definitive answers about compatibility, electrical effects or risks in those patients.

C-MIC IV to Test the Approach

The next major evaluation described at the meeting is C-MIC IV, a planned 60-person sham-controlled crossover trial. It is expected to test the subcutaneous device in participants with left-ventricular ejection fractions of 20% to 40%, including people with ischemic as well as non-ischemic heart failure. That expands the population beyond the earlier studies, which excluded ischemic cardiomyopathy and people with previously implanted devices.

The planned trial should provide a more rigorous comparison than the current small studies, but its size means questions may remain even after results are available. The source report did not specify the trial’s start date, expected completion date or a timetable for results. Until those data emerge, C-MIC should be regarded as an investigational therapy, not an established heart-failure treatment.

Key Questions

What is cardiac microcurrent therapy?

C-MIC is an investigational implanted device that delivers microcurrents to the heart. Researchers propose that it may affect heart tissue changes linked to impaired function, but the mechanism and clinical benefits have not been established.

Did the new analysis prove that C-MIC works?

No. The post hoc analysis found differences favoring C-MIC on some six-month exercise-test measures, but it involved 42 participants and was not a new, large confirmatory trial. One reported peak VO2 comparison did not reach statistical significance.

What is different about the subcutaneous device?

Instead of a surgical epicardial implant, the subcutaneous system places its generator and lead under the skin, with lead position checked by fluoroscopy. Early experience involved 10 first-in-human recipients, so the approach needs larger studies.

What will C-MIC IV test?

The planned 60-person sham-controlled crossover trial is expected to test the subcutaneous device in people with ejection fractions of 20% to 40%, including participants with ischemic and non-ischemic heart failure. Timing and results are not yet specified in the report.

Source: rss