People with hypertrophic cardiomyopathy (HCM) — often an inherited disease marked by abnormally thickened heart muscle — face a looming risk of heart failure, arrhythmia, and sudden cardiac arrest. Many experience no signs and don’t realize they have the condition, while others suffer progressively worse symptoms such as chest pain, shortness of breath, and palpitations. HCM can make exercise unsafe and is the leading cause of sudden cardiac death among young athletes, though such events are rar