Differential Rates of Guideline-Directed Medical Therapy Modification in C-MIC and Control Patients: Results from the C-MIC II Trial.

BACKGROUND: In the C-MIC II trial, C-MIC therapy improved outcomes in patients with heart failure (HF) with reduced ejection fraction (HFrEF). We evaluated whether differences in background HF medication adjustments influenced the observed benefits. METHODS: Ambulatory patients with chronic non-ischemic HFrEF receiving guideline-directed medical therapy (GDMT) were enrolled. The primary outcome was change in GDMT and diuretic intensity over 6 months. Treatment effects on left ventricular ejection fraction (LVEF), Kansas City Cardiomyopathy Questionnaire Overall Summary Score (KCCQ-OSS), and 6-minute walk distance (6MWD) were assessed by baseline sodium-glucose cotransporter-2 inhibitor (SGLT2i) use for consistency. RESULTS: Among 65 patients, 25 (39%) had GDMT adjustments (C-MIC device: 44%; control 33%; p= 0.390). GDMT intensity increased in controls (Δ +0.36) but decreased (Δ -0.16; p= 0.100) in C-MIC group. Diuretic intensity decreased in C-MIC group (Δ -0.10) but increased in controls (Δ +0.12; p= 0.200). When stratified by baseline SGLT2i use, C-MIC therapy induced consistent improvements in LVEF (SGLT2i: +6% [95% CI 3-9; p<0.001] vs. without SGLT2i: +4% [95% CI 2-7; p=0.003]), KCCQ-OSS (SGLT2i: +42 points [95% CI 26-58; p<0.001] vs. without SGLT2i: +40 [95% CI 28-51; p<0.001]) and 6MWD (SGLT2i: +150 meters [95% CI 88-212; p<0.001] vs. without SGLT2i: +141 meters (95% CI 63-219; p<0.001]). CONCLUSION: Medication intensity decreased in C-MIC-treated patients but increased in controls, driven primarily by escalation of diuretics, likely reflecting worsening HF. Consistent improvements in LVEF, 6MWD and KCCQ-OSS across SGLT2i subgroups suggest that the observed benefits are independent of background pharmacologic intensification.