FDA Expands Camzyos to Teenagers With Obstructive Hypertrophic Cardiomyopathy

The FDA has expanded the approval of Camzyos (mavacamten), from Bristol Myers Squibb, to include adolescents aged 12 to 17 (weighing at least 30 kg) with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). Announced on October 1, 2026, the decision makes Camzyos an option to improve functional capacity and symptoms in teenagers with a condition that, until now, had no approved targeted medicine for their age group.

What hypertrophic cardiomyopathy is

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease, affecting roughly one in 500 people. Gene variants cause the heart muscle to contract too forcefully and to grow abnormally thick, particularly the wall between the two lower chambers. In the obstructive form, the thickened muscle partly blocks blood leaving the heart. People may have breathlessness, chest pain, palpitations, dizziness or fainting, especially during exertion. HCM is also a leading cause of sudden cardiac death in young people, including athletes.

Why teenagers need options

HCM often emerges or worsens during adolescence, when the body is growing quickly. Teenagers with symptoms have relied on older drugs such as beta blockers and calcium channel blockers, which ease symptoms without addressing the cause, on restrictions on sport and exercise, and, in severe cases, on open-heart surgery to remove thickened muscle. Symptoms and activity limits can weigh heavily at an age when school, sport and social life matter enormously.

How Camzyos works

Camzyos is a cardiac myosin inhibitor. Myosin is the motor protein that powers each heartbeat; in HCM, too many myosin motors engage at once, so the heart over-contracts and cannot relax properly. Mavacamten dials down that excess contraction, reducing the obstruction and letting the heart fill more easily. It was the first drug to target the underlying mechanism of the disease, and was approved for adults in 2022.

The trial behind the approval

The expansion is based on SCOUT-HCM, a Phase 3, double-blind, randomized trial in 44 adolescents aged 12 to under 18. After 28 weeks, those on Camzyos had a statistically significant reduction in the pressure gradient across the heart’s outflow tract, the standard measure of obstruction, compared with placebo.

Safety

Because Camzyos weakens contraction, its main risk is weakening it too much, reducing the heart’s pumping function. In SCOUT-HCM, no patient’s ejection fraction fell below 50%, no one stopped treatment because of side effects, and serious adverse events were similar between groups (two patients on Camzyos, two on placebo). No new safety concerns were identified. In adults, the drug is prescribed under a safety program requiring regular echocardiograms to check heart function, and attention to drug interactions.

How HCM is found and managed in young people

HCM in teenagers is often picked up after a relative is diagnosed, after a heart murmur or abnormal ECG is noticed, or following symptoms such as fainting during exercise. Diagnosis rests on an echocardiogram, sometimes with cardiac MRI and genetic testing. Management is about more than symptoms: cardiologists assess each patient’s risk of dangerous heart rhythms and may recommend an implantable defibrillator for those at highest risk. Advice on sport has also shifted in recent years, away from blanket bans and toward individual decisions made with a specialist. A drug that reduces obstruction adds to that toolkit; it does not replace rhythm-risk assessment or family screening.

How widely it is used

According to BMS, more than 25,000 patients in the US have been treated with Camzyos, prescribed by over 5,000 clinicians, and it is cleared in more than 60 countries. The company says discussions with regulators elsewhere about pediatric use are under way. BMS senior vice president Al Reba called the approval “an important milestone for young patients and families facing a serious cardiovascular disease with significant unmet medical need.”

What it doesn’t cover

The approval applies only to the obstructive form of HCM. Many patients have non-obstructive disease, where the muscle is thickened but does not block blood flow; a large trial of mavacamten in that group did not meet its goals. The trial in teenagers was also small and short, measuring obstruction rather than long-term outcomes such as heart failure or sudden death, and it does not cover children under 12.

A growing drug class

Camzyos is no longer the only cardiac myosin inhibitor: a second drug in the class, aficamten, has reached the market for adults, giving cardiologists a choice. Competition is likely to bring more data on which patients benefit most, and whether these drugs can change the long-term course of the disease rather than just relieve symptoms.

What it means for families

For teenagers whose symptoms are not controlled by standard medicines, the approval offers a targeted option that may reduce obstruction and improve the ability to be active, potentially delaying or avoiding surgery. Because HCM runs in families, a diagnosis in one person should prompt screening of close relatives. Decisions about treatment and exercise should be made with a cardiologist experienced in HCM. This is regulatory news, not medical advice.