Hypertrophic Cardiomyopathy (HCM) is a genetic condition characterized by the thickening of the heart muscle. This thickening reduces the size of the heart’s left ventricular cavity, impairing the heart’s ability to pump blood effectively and causing the muscle to stiffen. HCM is the most common cause of sudden cardiac death (SCD) in young athletes, making the decision about sports participation require strict, personalized medical guidance.
Why Physical Exertion Poses a Danger
Intense physical exertion increases the strain on a heart compromised by Hypertrophic Cardiomyopathy. During maximal effort, the body demands increased oxygenated blood flow, which the thickened heart muscle struggles to meet. The heart’s stiffened walls and smaller chamber size prevent it from filling properly and pumping the required volume of blood (impaired diastolic function).
Maximal exercise triggers a surge of adrenaline and catecholamines, which can cause electrical instability. This stress, combined with high oxygen demand, can lead to a temporary reduction in blood flow to the inner heart muscle (subendocardial ischemia). The primary danger is that this physiological stress leads to life-threatening arrhythmias, such as ventricular tachycardia or ventricular fibrillation, which cause sudden cardiac arrest.
The Required Medical Evaluation for Athletes
Any individual with Hypertrophic Cardiomyopathy considering physical activity must undergo evaluation by a cardiologist specializing in inherited heart diseases or sports cardiology. This process starts with a detailed review of the patient’s and family’s medical history, checking for unexplained syncope, chest pain during exertion, or sudden cardiac death in relatives under 40.
Diagnostic testing is required to assess the condition’s severity and the individual’s risk profile. A transthoracic echocardiogram measures left ventricle thickness and assesses blood flow, looking for obstruction. This imaging is complemented by an electrocardiogram (EKG) to detect abnormal electrical patterns and ambulatory monitoring (Holter monitor) to capture non-sustained ventricular arrhythmias.
A stress test, often combined with an echocardiogram, observes how the heart responds to exertion, looking for an abnormal blood pressure response or outflow tract obstruction. Genetic testing may also be recommended to identify the specific mutation and inform prognosis. The final decision on activity level involves shared decision-making, weighing the benefits of exercise against the risk of a life-threatening event.
Categorizing Safe Versus Restricted Activities
Guidelines for sports participation separate high-intensity, high-risk activities from low-to-moderate recreational activities. Competitive sports are high-risk because they involve intense, sustained exertion and adrenaline surges. Athletes diagnosed with HCM are advised not to participate in most competitive sports.
Prohibited sports have both high static and high dynamic components, requiring sustained muscle tension and bursts of high-speed movement. Activities involving significant weightlifting or isometrics are also restricted due to the high static pressure placed on the heart. The high cardiovascular demand in these sports acts as a dangerous trigger for ventricular arrhythmias. Examples include:
- Basketball
- Ice hockey
- Soccer
- Competitive running
- Football
Activities considered low-risk are typically non-competitive and maintain a steady, low heart rate. These low-intensity activities have minimal to moderate dynamic and static components. Examples include low-intensity walking, golf, bowling, and leisurely cycling. Medical evidence supports the safety and benefit of personalized, low-to-moderate intensity exercise programs for HCM patients compared to a sedentary lifestyle. This personalized approach allows some sports with moderate dynamic components to be considered safe, provided the patient has a low-risk profile and consistent clinical surveillance. Intensity must be managed to prevent heart rates that trigger a dangerous response.
How Implantable Devices Affect Participation
For individuals with Hypertrophic Cardiomyopathy at high risk for sudden cardiac death, an Implantable Cardioverter-Defibrillator (ICD) may be recommended to terminate life-threatening arrhythmias. An ICD delivers an electrical shock to restore a normal heart rhythm if a dangerous arrhythmia is detected. While the device acts as a safety net, its presence does not automatically grant permission to return to high-risk competitive sports.
The primary restriction is the risk of device malfunction and injury during high-impact or contact sports. Direct impact to the chest can damage the ICD generator or cause the leads to fracture or dislodge, potentially preventing the device from working or leading to inappropriate shocks. High-intensity activity also increases the likelihood of receiving a shock, which may be triggered inappropriately by a fast, non-lethal heart rhythm. Receiving a shock during competition can cause injury, syncope, and psychological distress.