Highlights from

ACC 2021

American College of Cardiology Annual Congress 2021

Virtual 15-17 May 2021

Mavacamten emerges as a new therapy for hypertrophic cardiomyopathy

Summary: Mavacamten improved the function and quality of life in patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM) compared with placebo. Prof John Spertus (St. Luke’s Mid America Heart Institute, US) presented a health status analysis of the previously published phase III EXPLORER-HCM trial results.1-3

Current guideline-recommended pharmacological management of HCM consists mainly of beta-blockers or calcium channel blockers. Mavacamten is a first-in-class myosin inhibitor that directly addresses the pathophysiological mechanism underlying HCM. The EXPLORER-HCM (NCT03470545) trial was a phase III randomised, double-blind, placebo-controlled study that compared the outcomes in patients with obstructive HCM treated with mavacamten (n=123) with those treated with a placebo (n=128).2 Patients received a once-daily dose of either mavacamten or placebo for 30 weeks followed by an 8-week washout period, for a total intervention of 38 weeks. The Kansas City Cardiomyopathy Questionnaire (KCCQ) was administered at baseline and again at weeks 6, 12, 18, 30 (end of treatment), and 38 (end of study). The KCCQ asks about symptoms, physical function, social function, and quality of life. Scores can range from 0 (ie poor score) to 100 (ie favourable score). At week 30, 36% of participants in the mavacamten arm had achieved clinically meaningful improvements in their KCCQ score, as compared with only 15% of participants in the placebo arm. Conversely, at week 30, a greater proportion (23%) of patients in the placebo arm showed either no change or a deterioration in their KCCQ score, as compared with only 9% in the mavacamten arm. Significantly, this improvement was no longer realised at week 38 (ie following the washout period). Researchers concluded that mavacamten represents a new potential strategy for improving symptoms, activities of daily living, and patient satisfaction.

  1. Spertus J A. Health status benefits of mavacamten in patients with symptomatic obstructive hypertrophic cardiomyopathy: results from the EXPLORER-HCM randomized clinical trial. ACC 2021 Scientific Session, 15-17 May 2021
  2. Olivotto I, Oreziak A et al. Mavacamten for treatment of symptomatic obstructive hypertrophic cardiomyopathy (EXPLORER-HCM): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet 2020;396:759-769 [full text] (subscription required)
  3. Spertus J A, Fine J T. Mavacamten for treatment of symptomatic obstructive hypertrophic cardiomyopathy (EXPLORER-HCM): health status analysis of a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet 2021 online 15 May 2021 [full text] (subscription required)

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Article image: J-Elgaard

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