A recent analysis of over 6,000 patients receiving mavacamten through the FDA's Risk Evaluation and Mitigation Strategy (REMS) program confirms the drug's continued effectiveness in treating obstructive hypertrophic cardiomyopathy (HCM). The study, presented at the 2024 American Heart Association Scientific Sessions, revealed that few patients experienced left ventricular dysfunction or heart failure after one year of treatment.
The findings, also published in Circulation: Heart Failure, echo earlier studies, reinforcing mavacamten's potential to improve the quality of life for HCM patients and reduce the need for septal reduction therapy (SRT). According to Dr. Milind Desai, Director of the Hypertrophic Cardiomyopathy Center at Cleveland Clinic and lead author of the study, this is the largest study to date on mavacamten, showing favorable outcomes in a broad U.S. population.
Mavacamten: A Novel Cardiac Myosin Inhibitor
Mavacamten, a novel cardiac myosin inhibitor, is the first drug approved in the U.S. for symptomatic obstructive HCM. Clinical trials have demonstrated its ability to improve left ventricular outflow tract (LVOT) gradient, alleviate symptoms, enhance physical function, and decrease the necessity for SRT. However, due to its potential to reduce left ventricular ejection fraction (LVEF) and cause heart failure, mavacamten is available only through the REMS program, which mandates regular monitoring for heart failure and LVEF below 50% via echocardiograms, as well as screening for drug interactions.
Key Findings from the REMS Analysis
The REMS database included 6,299 patients treated with mavacamten between April 2022 and February 2024, with 60% being women and 65% over the age of 60. Among the 5,573 patients with submitted status forms:
- 4.6% reported LVEF below 50%
- 1.3% reported hospitalization for heart failure
- 0.3% reported both
For the 1,929 patients treated for at least one year, the percentages were similar or lower:
- 4.0% reported LVEF below 50%
- 1.5% reported hospitalization for heart failure
- 0.2% reported both, but later resumed treatment at a lower dose
Additional findings indicated that 57% of patients treated for at least six months achieved a post-Valsalva LVOT (vLVOT) gradient under 30 mmHg at three months, increasing to 70% at six months. The majority (97%) started treatment with the recommended 5 mg daily dose, and 74% continued on 5 mg or 10 mg per day to maintain vLVOT gradient reduction, with only 6% requiring the highest dosage of 15 mg per day.
Clinical Implications and Future Directions
Dr. Desai emphasized the significance of the findings, noting that very few patients experienced LVEF under 50% or heart failure symptoms requiring hospitalization, and those who did often resumed treatment. The REMS program's effectiveness in monitoring patient safety was also highlighted, with high compliance from prescribers and pharmacies and minimal instances of contraindicated medications or dose reductions due to drug interactions.
Dr. Maran Thamilarasan, a Cleveland Clinic cardiologist, noted the consistency between the real-world REMS data and clinical trial results, expressing anticipation for longer-term data on the medication's effects and benefits. Future research may explore the possibility of reducing the frequency of echocardiograms required for monitoring.
The study was funded by Bristol Myers Squibb, the parent company of MyoKardia, the developer of mavacamten.
