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BACKGROUND: In nonobstructive hypertrophic cardiomyopathy (nHCM), there are no approved medical therapies. Impaired myocardial energetics is a potential cause of symptoms and exercise limitation. Ninerafaxstat, a novel cardiac mitotrope, enhances cardiac energetics. OBJECTIVES: To evaluate the safety and efficacy of ninerafaxstat in nHCM. METHODS: Patients with HCM and left ventricular (LV) outflow gradient <30 mmHg, ejection fraction ≥50% and peak VO2 <80% predicted, were randomized to ninerafaxstat 200 mg BID or placebo (1:1) for 12 weeks. Primary endpoint was safety and tolerability with efficacy outcomes also assessed as secondary endpoints. RESULTS: A total of 67 patients with nHCM were enrolled at 12 centers (57 yrs ± 11.8; 55% women). Serious adverse events occurred in 11.8% (4/34) in the ninerafaxstat group and 6.1% of patients (2/33) in placebo. From baseline to 12 weeks, ninerafaxstat was associated with significantly better ventilatory efficiency (VE/VCO2 slope) compared to placebo with a least square (LS) mean difference between the groups of -2.1 (95% CI, -3.4, -0.6; p=0.006), with no significant difference in pVO2 (p=0.9). KCCQ-CCS was directionally though not significantly improved with ninerafaxstat vs. placebo (LS mean, 3.2 [95% CI, -2.9, 9.2; p=0.2]), though was statistically significant when analyzed post-hoc in the 35 patients with baseline KCCQ-CSS ≤80 (LS mean, 9.4 [95% CI, 0.2, 18.5; p=0.04]). CONCLUSIONS: In symptomatic nHCM, novel drug therapy targeting myocardial energetics was safe and well tolerated and associated with better exercise performance and health status among those most symptomatically limited. The findings support assessing ninerafaxstat in a Phase 3 study.

Original publication




Journal article


J Am Coll Cardiol

Publication Date



cardiac energetics, clinical trial, exercise capacity, health status, ninerafaxstat, nonobstructive hypertrophic cardiomyopathy