Efficacy and Safety of Mavacamten in the Treatment of Hypertrophic Cardiomyopathy: A Systematic Review

BACKGROUND: Current pharmacological options for hypertrophic cardiomyopathy (HCM) are not disease-specific; while it treats symptoms, mavacamten targets the underlying pathology. We aim to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive HCM.

METHODS: This systematic review of the literature followed the PRISMA guidelines. Title/abstract and topics were searched using the following term: "mavacamten". The electronic research literature databases included the Cochrane Library, MedLine, and clinicaltrials.gov from July to August 2022. Primary efficacy endpoint was to assess clinical response at the end of treatment compared with baseline, defined as, at least one New York Heart Association (NYHA) class reduction. Two secondary endpoints from baseline were determined. The first was defined as improvement in mixed venous oxygen pressure (pVO2). The second was defined as reduction of the post-exercise left ventricular outflow tract (LVOT) gradient.

RESULTS: We included in our analyses data from four studies that met our review eligibility criteria. There were three randomised placebo-controlled clinical trials and one non-randomised open-label clinical trial. All four studies showed a reduction in NYHA class from mavacamten use. Three out of four studies demonstrated >1 NYHA functional class improvement ranging from 34% to 80%, while only one study showed a smaller percentage of patients remaining at class 3. Three out of four studies measured pVO2 as an outcome, and all three studies noticed an increase in peak oxygen consumption after mavacamten treatment. Additionally, three out of four studies measured post-exercise LVOT gradient reduction as an outcome and all three found significant reduction in the post-exercise LVOT gradient after treatment. The most commonly observed adverse side effects were atrial fibrillation and decreased left ventricular ejection fraction, but all participants recovered without long-term sequelae and only one patient dropped out of the trial.

CONCLUSIONS: Mavacamten has a greater efficacy than placebo in the treatment of HCM. It also showed promising tolerability and efficacy profiles in the treatment of HCM in adults. The three endpoints used in the evaluation of studies were reduction in NYHA class, increase in pVO2, and post-exercise LVOT gradient reduction. Mavacamten showed greater reduction in NYHA, larger effects on increase of pVO2, and significant reduction of the LVOT gradient. Mavacamten was also found to be well tolerated, like the placebo. The side effect profile was limited for the majority of individuals taking mavacamten. In the future, authors recommended dose-optimisation studies, and studies that evaluate mavacamten both in comparison to, and in conjunction with other current treatments.