Aficamten Shows Major Promise for Nonobstructive HCM
Managing patients with nonobstructive hypertrophic cardiomyopathy remains a major clinical challenge. Until now, clinicians lacked proven medical therapies to address the underlying disease biology. However, recent phase 3 results from the ACACIA-HCM trial demonstrate meaningful clinical progress. Investigators evaluated aficamten, a novel cardiac myosin inhibitor, in patients with symptomatic nonobstructive disease.
Trial Design in Nonobstructive Hypertrophic Cardiomyopathy
The ACACIA-HCM study was a multinational, double-blind, randomized trial. Researchers enrolled 517 adult patients across global medical centers. Participants received either oral aficamten or placebo for up to 72 weeks. The starting dose was 5 mg daily, with titration up to 20 mg based on echocardiographic response. Additionally, investigators selected dual primary endpoints to evaluate functional and subjective responses. These endpoints measured changes in peak oxygen uptake and Kansas City Cardiomyopathy Questionnaire scores at week 36.
Key Clinical Efficacy and Safety Findings
Patients receiving aficamten achieved statistically significant improvements across both primary endpoints. Specifically, the KCCQ clinical summary score increased by 11.4 points with aficamten compared to 8.4 points with placebo. Peak oxygen consumption also improved significantly in the aficamten cohort. Furthermore, secondary outcomes such as functional class and biomarker levels favored the active drug. In terms of safety, reversible reductions in ejection fraction below 50% occurred in 10.5% of aficamten patients. Consequently, careful echocardiographic monitoring remains essential during active dose adjustments.
Clinical Implications for Practice
These findings provide strong evidence for targeted myosin inhibition in this underserved population. Currently, physicians rely mainly on empiric symptom management with standard cardiac medications. Therefore, aficamten represents a potential breakthrough in disease-specific management. Clinicians can expect improved exercise capacity and enhanced daily functioning for their symptomatic patients.
Frequently Asked Questions
Q1: What is the mechanism of action of aficamten?
Aficamten is a selective cardiac myosin inhibitor that reduces excessive myocardial contractility and relaxes heart muscle.
Q2: What were the primary endpoints of the ACACIA-HCM trial?
The trial evaluated changes at 36 weeks in peak oxygen uptake and the Kansas City Cardiomyopathy Questionnaire score.
Q3: How was left ventricular ejection fraction managed during the trial?
Clinicians monitored ejection fraction regularly via echocardiography and adjusted medication doses if values fell below 50%.
References
- Masri A et al. Aficamten for Symptomatic Nonobstructive Hypertrophic Cardiomyopathy. N Engl J Med. 2026 Aug 28. doi: 10.1056/NEJMoa2603021. PMID: 42663312.
- European Society of Cardiology. Aficamten trial brings positive news for patients living with non-obstructive hypertrophic cardiomyopathy. ESC Congress 2026 News.
