Precision Medicine Breakthrough: Mavacamten Markedly Reduces Heart Obstruction in Teens with Hypertrophic Cardiomyopathy

Children's Hospital of Philadelphia findings offer hope for pediatric cardiac patients and their families

PHILADELPHIA, March 29, 2026 /PRNewswire/ -- Researchers at Children's Hospital of Philadelphia (CHOP) reported today that adolescents with hypertrophic cardiomyopathy (HCM) who took mavacamten experienced reduced obstruction, allowing blood to flow more easily from the heart. The research, presented today at the American College of Cardiology's Annual Scientific Session in New Orleans, was also published in the New England Journal of Medicine.

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease and is characterized by abnormal thickening and stiffness of the heart muscle, which can obstruct blood flow. HCM can cause chest pain, dizziness, shortness of breath, and swelling, and can progress to heart failure, dangerous arrhythmias or sudden cardiac death. Mavacamten, a medication that reduces myosin activity to improve cardiac function, is approved for adults. However, this research is the first to assess the drug in adolescents, who typically have more severe disease.

"I've cared for children with obstructive hypertrophic cardiomyopathy for decades, and treatment options have been limited to symptom-focused medications or invasive surgery," said Joseph Rossano, MD, MS, the study's lead author and Chief of the Division of Cardiology at Children's Hospital of Philadelphia. "If this drug receives FDA approval for teens, it could offer a transformative, precision medicine approach as the first pediatric-specific targeted therapy for this condition."

In the study, global trials sites enrolled 44 teens (ages 12 to <18) with symptomatic obstructive HCM. Of those, 23 participants randomly received mavacamten and 21 received a placebo for 28 weeks. The trial was double-blind, meaning that neither families nor doctors knew who got the drug. The researchers measured change in the pressure gradient across the heart's outflow tract during a Valsalva maneuver (a standard way to provoke the obstruction) from the start to week 28.

After 28 weeks, patients taking mavacamten experienced a significant drop in the blockage leaving the heart (about 48.5 mm Hg) compared with almost no change (0.5 mm Hg) in the placebo group. Side effects were similar in both groups, and all patients met a key safety threshold. Overall, mavacamten greatly reduced the obstruction in adolescents with HCM and appeared safe in this study.

Additionally, blood markers that indicate heart damage fell in patients taking mavacamten but rose in those on placebo. That pattern suggests mavacamten may do more than ease symptoms; it could slow disease progression and even reverse some damage to the heart.

"These results are encouraging as they suggest the drug might help the heart heal, changing the patient's underlying biology over time instead of just relieving symptoms," said Rossano. "If these findings are confirmed with further research, we'll want to look at starting treatment in children sooner, before the heart has experienced years of damage."

This study was supported by Bristol Myers Squibb.

Joseph Rossano, MD, is a paid consultant to Bristol Myers Squibb and served as the site principal investigator for the SCOUT-HCM Study at Children's Hospital of Philadelphia.

Rossano et al. "Mavacamten in Adolescents with Obstructive Hypertrophic Cardiomyopathy." NEJM. Online March 29, 2026.

About Children's Hospital of Philadelphia:
A non-profit, charitable organization, Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals, and pioneering major research initiatives, the hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country. The institution has a well-established history of providing advanced pediatric care close to home through its CHOP Care Network, which includes more than 50 primary care practices, specialty care and surgical centers, urgent care centers, and community hospital alliances throughout Pennsylvania and New Jersey. CHOP also operates the Middleman Family Pavilion and its dedicated pediatric emergency department in King of Prussia, the Behavioral Health and Crisis Center (including a 24/7 Crisis Response Center) and the Center for Advanced Behavioral Healthcare, a mental health outpatient facility. Its unique family-centered care and public service programs have brought Children's Hospital of Philadelphia recognition as a leading advocate for children and adolescents. For more information, visit https://www.chop.edu. 

Contact: Natalie Solimeo
Children's Hospital of Philadelphia
267-426-6246
[email protected]

SOURCE Children's Hospital of Philadelphia