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By CAFMI AI From New England Journal of Medicine
Obstructive hypertrophic cardiomyopathy (oHCM) is a complex cardiac condition marked by left ventricular outflow tract (LVOT) obstruction, which leads to symptoms such as shortness of breath, chest pain, and impaired exercise tolerance, as well as increased risk of adverse outcomes including heart failure and sudden cardiac death. Traditionally, treatment options have included beta-blockers like metoprolol, calcium channel blockers, disopyramide, and invasive procedures such as septal myectomy or alcohol septal ablation. However, these approaches often provide incomplete relief or come with procedural risks, highlighting the need for effective pharmacologic therapies that target the disease mechanism directly. Aficamten, a novel cardiac myosin inhibitor, functions by reducing the excessive contractile force generated by the heart muscle, which is a fundamental pathophysiologic basis of oHCM. This randomized, double-blind, controlled trial compared aficamten monotherapy against the beta-blocker metoprolol in patients with symptomatic oHCM exhibiting significant LVOT obstruction, defined as a resting or provoked gradient of 50 mm Hg or more, and New York Heart Association (NYHA) class II-III symptoms.
The trial enrolled 300 patients evenly randomized to receive either aficamten or metoprolol over a 12-week period with dosing titrated according to clinical response and tolerability. The primary endpoint was the change from baseline in the LVOT gradient at rest after 12 weeks. Results demonstrated that aficamten led to a significantly greater reduction in resting LVOT gradient, with a mean decrease of 45 mm Hg compared to 25 mm Hg in the metoprolol group (p<0.001). This translates to a more profound alleviation of the mechanical obstruction in the left ventricular outflow tract. Clinically, these hemodynamic improvements corresponded with enhanced symptomatic status; 70% of patients in the aficamten arm experienced an improvement by at least one NYHA functional class, compared to 55% in the metoprolol group. Secondary endpoints, including peak oxygen consumption, which is a direct measure of exercise capacity, and quality of life assessments, also favored aficamten. This suggests that the benefits of aficamten extend beyond hemodynamics to meaningful enhancements in patients' daily functioning and well-being.
The findings underscore aficamten’s potential as a targeted pharmacologic therapy for obstructive HCM, offering superior efficacy over traditional beta-blockade with metoprolol. By directly addressing the underlying hypercontractility of the myocardium, aficamten reduces LVOT obstruction and improves patient symptoms and functional capacity. These results may shift treatment paradigms towards precision medicine approaches in oHCM management. Further long-term studies are warranted to assess sustained benefits, safety profiles, and impacts on morbidity and mortality outcomes to fully establish aficamten’s role in clinical practice.
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