Hypertrophic Cardiomyopathy in Black Patients: Catch It Early

Hypertrophic cardiomyopathy, or HCM, is a genetic condition where the heart muscle grows too thick. It is the most common inherited heart disease, affecting roughly 1 in 500 people, and it is one of the leading causes of sudden cardiac death in people under 35, including athletes. Here is the part that gets lost: HCM is treatable, and most people who have it and get the right care live a normal lifespan. The thickened muscle can be seen on an ultrasound of the heart. The people at highest risk can be protected. The danger for Black patients is not the disease itself. It is getting to the diagnosis and the specialist too late.

In HCM, a gene that controls how heart muscle is built carries a change, and the wall of the heart's main pumping chamber thickens. The CDC describes it as the most common inherited heart disease, where the heart muscle is thickened. That thick muscle can block blood leaving the heart, stiffen the chamber so it fills poorly, and disrupt the heart's electrical signals. In some people that electrical disruption triggers a dangerous rhythm, which is why HCM is a known cause of sudden death in adolescents and young athletes.

A lot of people with HCM feel nothing for years. The CDC notes that a person may have no symptoms at all, which is exactly why a family history matters and why it is sometimes found only after a relative collapses. The condition is common: a 2015 analysis in the Journal of the American College of Cardiology put the prevalence at about 1 in 500 and argued the true number is probably higher, because many cases are never identified.

The largest look at this question followed 2,467 patients with HCM across a multi-center registry and was published in JAMA Cardiology in 2020. The Black patients in that registry were diagnosed younger, at an average age of 36, and they were more likely to arrive already in advanced heart failure: about 23 percent presented in NYHA class III or IV, the stages where everyday activity leaves you short of breath. That is a picture of disease that was caught late, after symptoms had time to build.

Part of the late catch is misattribution. Thick heart muscle in a Black patient is easy to blame on long-standing high blood pressure, which is also common and also thickens the heart wall. In a young, active patient, the same thick muscle gets explained away as an athlete's heart, a normal adaptation to training. Both explanations can be wrong, and both can send a real HCM diagnosis years down the road. Symptoms like breathlessness or palpitations get attributed to weight, stress, or being out of shape instead of triggering an ultrasound of the heart.

The same registry showed the gap continues after diagnosis. Black patients received genetic testing less often (about 54 percent versus 62 percent) and had a sarcomere gene change identified less often. That second number is partly biology, because the gene panels were built mostly from people of European ancestry and miss variants more often in Black patients, and partly a testing gap. Either way, a family loses the chance to screen relatives with a known gene. Black patients also underwent septal reduction, the procedure that relieves a blocked heart, less often: about 15 percent versus 23 percent. The authors concluded these patterns reflect inequities in care, not milder disease.

A separate 2021 analysis in the Journal of the American Heart Association found the same shape in a different group of Black HCM patients: younger at diagnosis, more than a third in NYHA class III or IV, and a low rate of genetic testing. When the same gaps show up in two independent studies, the message is consistent. The fix is not waiting and watching. It is getting to a cardiologist and, when HCM is confirmed, to a center that treats it.

HCM does not always announce itself, but when it does, these are the signals that should lead to an echocardiogram and an ECG, not reassurance:

• Fainting or near-fainting during or right after exertion. This is the one to take most seriously. Passing out while working out, playing, or running is not normal and needs a heart workup.
• Chest pain or pressure, especially with activity.
• Shortness of breath that is new or worse than your fitness explains.
• Heart palpitations, a racing, pounding, or fluttering heartbeat.
• A family history of sudden, unexplained, or early death, particularly anyone who died suddenly before 50, drowned for no clear reason, or died in a single-car crash with no explanation.

Diagnosis is straightforward once someone looks. An echocardiogram (an ultrasound of the heart) shows the thickened muscle and whether blood flow out of the heart is blocked. An ECG records the electrical pattern and is abnormal in most people with HCM. A cardiac MRI and a Holter monitor add detail. None of these require you to be sick first. If you have the warning signs or the family history, you can ask for them.

HCM runs in families. Each first-degree relative of a person with HCM, meaning every parent, sibling, and child, has about a 50 percent chance of carrying the same gene change. The 2024 American Heart Association and American College of Cardiology guideline recommends that first-degree relatives be evaluated, either with periodic heart imaging or, when the family's gene change is known, with genetic testing that can rule them in or out. This is the single highest-value action a family can take, because it finds at-risk relatives before a symptom or a collapse does. If someone in your family has been diagnosed with HCM, ask your own doctor for a referral to be screened.

HCM is one of cardiology's success stories. The 2024 AHA/ACC guideline lays out a clear ladder, and most people never need to climb past the first rung:

• Medications first. Beta-blockers and certain calcium channel blockers ease symptoms and relax the heart. They are the starting point for most people.
• Septal reduction for blocked blood flow that medication does not control. Septal myectomy, an open-heart operation that shaves away the thick muscle, has excellent results when done at a high-volume center. Alcohol septal ablation is a catheter-based alternative for selected patients.
• An implantable cardioverter-defibrillator (ICD) for people at high risk of sudden death. It sits under the skin and shocks a dangerous rhythm back to normal. The decision is based on a risk assessment, not on everyone.
• Mavacamten, a newer option. This drug (brand name Camzyos) was approved by the FDA in 2022 as the first medication that targets the overactive heart-muscle protein behind obstructive HCM. In the EXPLORER-HCM trial in The Lancet, 37 percent of patients on mavacamten met the main goal of improved exercise capacity and symptoms, compared with 17 percent on placebo.

Because Black patients are referred less often for septal reduction and genetic testing, the practical takeaway is to push for a specialist. HCM is managed best at centers that see a lot of it. If you have heart failure on top of HCM, our guide to heart failure in Black patients and why it starts earlier covers what to watch for.

Start with a cardiologist, and ask directly for an echocardiogram and an ECG if you have warning signs or a family history of sudden death. If HCM is confirmed, ask for a referral to a cardiomyopathy or HCM center of excellence, and ask about genetic counseling so your relatives can be screened. You can find a Black cardiologist in our directory who will take your symptoms and your family history seriously the first time. Bring a list: who in your family died young or suddenly, what symptoms you have and when they happen, and the question you most want answered.