Joseph Rossano, MD, discusses the benefits of mavacamten in HCM patients

In a recent interview with Contemporary Pediatrics, Joseph Rossano, MD, MS, FAAP, FACC, shared groundbreaking results from the SCOUT-HCM trial, a prospective, randomized, placebo-controlled study evaluating the safety and efficacy of mavacamten (Camzyos; MyoKardia, Inc) in pediatric patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM). The trial specifically targeted adolescents suffering from significant left ventricular outflow tract (LVOT) obstruction.

The study’s primary end point was the reduction of the Valsalva LVOT gradient at 28 weeks. Rossano reported a “dramatic reduction” in obstruction among those treated with mavacamten. Most patients achieved reductions to levels no longer classified as obstructive. Key secondary and exploratory end points—including maximal LVOT gradients, biomarkers of heart injury, and New York Heart Association Functional Classification—also showed significant improvement compared with the placebo group.

A critical point of discussion was whether these improvements represented true reverse remodeling or were merely secondary effects of gradient reduction. Rossano expressed optimism, noting that mavacamten is among the first therapies to target the underlying pathophysiology of HCM directly.

Historically, pediatric HCM treatment has relied on extrapolated adult data and symptom management, with questionable effectiveness. Seeing improvements in wall thickness and substantial drops in biomarkers suggests the potential for favorable heart remodeling and a shift in the disease’s natural history.

Despite the physiological data, patient-reported symptoms did not show a clear disparity in improvement during the 28-week study. Rossano attributed this complication to the lack of validated symptom scoring tools for pediatric HCM patients, a known limitation in the field. He emphasized that while exercise data showed these patients were physically limited, long-term data are essential to reconcile clinical markers with subjective symptoms.

Regarding safety, the trial reported very low adverse events, well balanced between the mavacamten and placebo groups. No patients experienced a drop in ventricular function below an ejection fraction of 50%, providing a reassuring safety signal for the use of cardiac myosin inhibitors in young populations. Rossano concluded that while the study was small, the results suggest mavacamten could fundamentally change the treatment paradigm for pediatric HCM, potentially sparing young hearts from the “relentless damage” caused by long-term obstruction.

No relevant disclosures.

Reference

A study to evaluate mavacamten in adolescents with symptomatic obstructive hypertrophic cardiomyopathy. ClinicalTrials.gov. Updated December 19, 2025. Accessed April 1, 2026. https://clinicaltrials.gov/study/NCT06253221