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Presentations at the Heart Failure Society of America meeting reported favorable findings from small studies of cardiac microcurrent therapy, including a reanalysis of exercise-test results and early experience with a less invasive implant. Researchers and a session discussant said the results need testing in larger, sham-controlled trials; the next planned study is expected to enroll 60 people.
Researchers presenting at the Heart Failure Society of America annual meeting reported additional favorable findings for cardiac microcurrent therapy, an implanted treatment being studied for heart failure, but experts cautioned that the evidence remains preliminary. A reanalysis of exercise-test data from the small C-MIC II trial and early results from a 10-person subcutaneous-implant study support further research, not a conclusion that the treatment works; a planned 60-person sham-controlled trial is intended to provide a stronger test.
In a post hoc analysis of C-MIC II, investigators reexamined six-month cardiopulmonary exercise test results using a blinded core laboratory. Among the 42 people included in that analysis, the reported change in absolute peak oxygen uptake was 208.7 mL/min with C-MIC, compared with 7.3 mL/min among non-implanted controls. The difference did not reach statistical significance (P=0.079). Other reported measures favored the treatment group: peak metabolic equivalents changed by 1.0 versus 0.1 (P=0.021), and percent-predicted peak VO2 changed by 13.8% versus 0.5% (P=0.021). Weight-adjusted peak VO2 increased by 2.70 mL/min/kg, according to the presentation.
Dragana Kosevic, MD, of Cardiovascular Institute Dedinje in Belgrade, said the objective exercise-test findings supported functional benefits seen in C-MIC II, while calling for larger randomized studies. The reanalysis addressed a limitation of the original trial, which used exercise-test values reported by trial sites without central adjudication. However, it was post hoc, included 42 participants, and only five of the trial’s seven sites contributed data.
A separate presentation examined a subcutaneous version of the device, in which the generator and lead are placed under the skin. Stefan Simovic, MD, of the University of Kragujevac described a comparison involving 10 C-MIC III participants with subcutaneous implants, 10 matched participants who had surgical implants in C-MIC II, and 10 matched controls from C-MIC II. The group reported comparable changes in ejection fraction, six-minute walking distance and quality-of-life scores. The comparison was small and drew on separate studies, so it cannot establish that the two implant approaches are equally effective.
A Less Invasive Implant Still Needs Testing
The work matters because it examines both whether C-MIC’s reported effects hold up under a more standardized exercise-test review and whether the device can be delivered without the earlier surgical approach. A subcutaneous procedure performed by an electrophysiologist in a catheterization lab under moderate sedation could broaden how the implant is delivered, if later studies establish safety and benefit. That practical possibility is distinct from proof of clinical effectiveness.
People with heart failure may already rely on established treatments and implanted devices. The current evidence does not show that C-MIC can replace or improve on those options. The unusually large exercise-capacity change drew direct skepticism at the meeting, underscoring why larger controlled trials are needed before patients or clinicians can judge the therapy’s likely benefit.
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From C-MIC II to C-MIC IV
C-MIC is intended to address electrical-field changes in heart muscle 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 affecting heart structure and function. This is a proposed biological explanation, not an established account of how the treatment produces clinical effects.
C-MIC II randomized 65 people with refractory, non-ischemic heart failure with reduced ejection fraction to surgical epicardial implantation or control. The original trial reported improvements in ejection fraction, symptoms, functional capacity and quality of life at six months; peak VO2 showed a favorable trend but did not reach statistical significance. C-MIC III is a first-in-human study of the subcutaneous approach. Its earlier six-month report described improvements from baseline, including a six-point rise in ejection fraction, a 90-meter increase in six-minute walking distance and a 30-point increase in the Kansas City Cardiomyopathy Questionnaire score. Those are within-study changes, not proof of benefit against a sham procedure.
“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 Veterans Affairs Health Care System and UCSF Medical Center
Effect Size and Device Safety Remain Open
The available studies are too small to settle whether C-MIC improves outcomes or establish the size of any benefit. C-MIC II was open-label and enrolled dozens, not hundreds, of participants; its exercise-test reanalysis was post hoc and not based on all seven sites. C-MIC III’s subcutaneous evidence came from only 10 implanted participants and a matched comparison with people in another trial. Matching cannot remove every difference between groups, and the C-MIC III participants had more advanced disease at baseline, including lower ejection fractions and greater ventricular dilation.
Safety questions also remain, particularly for people with existing implants or coronary stents. Teerlink raised concerns about possible interactions with implantable cardioverter-defibrillators, cardiac resynchronization therapy, baroreflex activation therapy, cardiac contractility modulation and stents. The meeting report did not establish whether such interactions occur or how they would be managed. It also remains unclear whether the favorable findings will persist in a sham-controlled study that includes a broader heart-failure population.
The Planned Sham-Controlled Test
The next major evaluation described at the meeting is C-MIC IV, a planned sham-controlled crossover trial of 60 people with left-ventricular ejection fractions between 20% and 40%. According to Simovic, it will use the subcutaneous device and include participants with both ischemic and non-ischemic heart failure, expanding beyond the groups included in C-MIC II and III. The source report did not provide a start date, recruitment timeline or expected completion date.
That trial will need to clarify whether the therapy’s effects exceed those associated with a sham procedure, and provide more information about safety in patients with other cardiac devices or stents. Until results are available, the presentations amount to early evidence supporting continued investigation rather than a basis for routine use.
Key Questions
What is cardiac microcurrent therapy?
C-MIC is an implanted system that delivers microcurrents to the heart. Researchers propose that it may affect heart-muscle structure and function, but its mechanism and clinical benefit remain under study.
Do the studies prove that C-MIC works?
No. The reported findings come from small studies and a post hoc analysis. The C-MIC II exercise-test analysis included 42 people, and the subcutaneous-implant comparison included 10 people with that device. Larger controlled trials are needed.
What did the exercise-test reanalysis find?
At six months, several measures favored C-MIC, including peak metabolic equivalents and percent-predicted peak VO2. The reported absolute peak VO2 difference did not reach statistical significance (P=0.079), and the analysis was post hoc.
What is the planned C-MIC IV trial?
As described at the meeting, C-MIC IV is a planned 60-person sham-controlled crossover trial of the subcutaneous device. It is expected to include people with ischemic and non-ischemic heart failure and ejection fractions from 20% to 40%; a timeline was not reported.
Is the subcutaneous device known to be safe with other heart implants?
The meeting report did not establish whether C-MIC interacts with devices such as defibrillators or cardiac resynchronization systems, or with coronary stents. Those questions remain unresolved and require study.
Source: rss
