At the European Society of Cardiology (ESC) Congress in Munich on Friday, cardiologists presented the first phase 3 trial to show benefit for patients with non-obstructive hypertrophic cardiomyopathy (HCM).
The ACACIA-HCM study of aficamten, a drug that dampens excessive heart-muscle contraction, met both of its primary goals.
That matters because HCM is the most common inherited heart disease and, per the ACC/AHA guideline, the leading cause of sudden cardiac death in young people.
Many patients live with symptoms for years before anyone connects the dots.
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HCM makes part of the heart muscle abnormally thick, which stiffens the pump and can disturb its rhythm.
The American Academy of Family Physicians, summarizing the ACC/AHA guideline, puts the asymptomatic prevalence at roughly one in 500 to one in 200 U.S. adults.
Symptoms typically appear with exertion and include chest pain, breathlessness, palpitations and fainting, but they are quiet enough that many people chalk them up to stress or being out of shape.
8 warning signs to know
1. Breathlessness that outstrips the effort. Stairs, a hill or a light bike ride leaves you fighting for air. A stiff, thickened left ventricle fills less well, so the lungs congest sooner than the workload should predict.
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2. Chest pressure during exertion. Not a sharp pang but a heavy squeeze or tightness, brought on by activity and eased by rest. The thickened muscle demands more oxygen than the coronary arteries can deliver under load.
3. Palpitations at rest or during exercise. A pounding, fluttering or "skipping" sensation, as Medical News Today describes it. The abnormal muscle disturbs the heart's electrical system and raises the risk of arrhythmia.
4. Fainting or near-fainting. A sudden drop-out on the field, on the stairs, or when standing up from a chair. The ACC/AHA guideline treats unexplained syncope as a marker of higher sudden-death risk.
5. Unexplained fatigue. Deep tiredness that adequate sleep does not fix. A less efficient pump means the body's tissues receive less oxygenated blood.
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6. Exercise intolerance beyond what fitness explains. Workouts you used to do easily now feel impossible, and progress stalls no matter the training plan. In HCM the limiter is the pump, not the muscles.
7. A heart murmur picked up incidentally. Many diagnoses begin when a clinician hears an unexpected murmur, or a routine ECG looks abnormal. HCM is often discovered this way.
8. Family history of sudden cardiac death before 50. Because HCM is inherited, the ACC/AHA guideline recommends the same evaluation for all first-degree relatives of a patient. A close family member who died suddenly and young is a signal that warrants cardiology assessment.
Why the new trial matters
For non-obstructive HCM, no drug had previously been proven to target the underlying hypercontractility. Aficamten is a cardiac myosin inhibitor, meaning it reduces excessive contraction of the heart muscle.
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In the ACACIA-HCM trial, 516 adults were randomized to aficamten or placebo. After 36 weeks, quality-of-life scores on the Kansas City Cardiomyopathy Questionnaire rose by 11.4 points on the drug versus 8.4 on placebo. Peak oxygen consumption rose by 0.64 mL/kg/min on aficamten versus a drop of 0.03 mL/kg/min on placebo.
Reduced pumping strength (left-ventricle ejection fraction below 50%) occurred in 10% of aficamten patients and 1% on placebo. Cytokinetics, the drug's developer, has said it will discuss the data with the U.S. FDA.
When to see a doctor
The ACC/AHA guideline calls for a three-generation family history, a physical exam, an ECG and an echocardiogram in anyone with suspected HCM.
Anyone with unexplained fainting during exercise, breathlessness that does not fit their fitness level, or a close relative who died suddenly and young should ask a physician for an evaluation.
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Under the current guideline, moderate-intensity exercise is safe and recommended in patients with stable HCM.
This article is made and published by Mie Hermansen, who may have used AI in the preparation.