A first-ever win for a disease with no treatments

For patients with nonobstructive hypertrophic cardiomyopathy (HCM), there have been no approved drugs — until now. The phase 3 ACACIA-HCM trial, presented at the European Society of Cardiology Congress 2026 and simultaneously published in the New England Journal of Medicine, showed that aficamten (Myqorzo), a cardiac myosin inhibitor already approved for obstructive HCM, significantly improved both symptom burden and exercise capacity in nonobstructive HCM patients — a historic first in a controlled trial.

Across 518 adults at 160 sites in 19 countries, aficamten beat placebo on both primary endpoints at 36 weeks, with benefits emerging as early as 12 weeks. A responder analysis found that 53% of aficamten-treated patients achieved a meaningful clinical response across multiple domains, versus just 13% on placebo. The drug was associated with a higher rate of LVEF reductions and early discontinuations, though all three deaths in the trial occurred in the placebo arm.

By the numbers:

• KCCQ score improvement: 11.4 pts (aficamten) vs. 8.4 pts (placebo) — a 3-point advantage (P = .02)
• Peak VO₂ change: +0.64 vs. −0.03 mL/kg/min — a 0.67 mL/kg/min difference (P = .003)
• Clinical responders (≥3 of 5 domains): 53% vs. 13% (P < .001)
• LVEF < 50%: 10.5% (aficamten) vs. 0.8% (placebo)
• Discontinuation due to adverse events: 7.0% vs. 1.9%

Why it matters: Nonobstructive HCM is a progressive, debilitating disease with no proven pharmacologic treatments beyond heart transplantation. These results position aficamten as a potential first-ever approved therapy for this population, pending regulatory review — a meaningful step forward for patients who currently have nowhere else to turn.