Efficacy of mavacamten in patients with hypertrophic cardiomyopathy and mid-ventricular obstruction: case series

Background: Mavacamten is a cardiac-specific myosin inhibitor approved for treatment of adults with hypertrophic cardiomyopathy (HCM) symptomatic for left ventricular outflow tract (LVOT) obstruction. Since obstruction is favoured by a hyper-contractile state, it would be logical to suppose that mavacamten may also be effective in patients with mid-ventricular obstruction (MVO). We present our experience with two HCM patients having MVO effectively treated with mavacamten. Case summary: The first case is a 55-year-old woman presenting with dyspnoea and exertional fatigue, with obstructive HCM (HOCM) and mid-ventricular peak gradient of 77 mmHg associated with LVOT obstruction. The treatment with mavacamten 5 mg daily determined relief of symptoms. At 16-week follow-up, there was a significant reduction of peak gradient (11 mmHg in mid-ventricular tract) and a significant decrease in NT-proBNP levels from 1287 to 178 ng/L. The second case is a 55-year-old woman with predominant mid-ventricular HOCM (peak gradient 52 mmHg) and past history of septal myectomy, with a residual significant gradient measured at LVOT level. The patient was started on mavacamten 5 mg daily, subsequently up-titrated to 10 mg. At 16-week follow-up, there was a significant reduction of peak gradient to 10 mmHg and a significant decrease in NT-proBNP levels from 3910 to 718 ng/L. Discussion: These two cases highlight the efficacy of mavacamten in the reduction of MVO, suggesting that it may be a valid therapeutic option also in patients with isolated MVO, frequently more difficult to be adequately treated.