Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people and athletes. Many patients, however, remain asymptomatic or only have a few symptoms. Diagnosis and risk stratification are based on a thorough clinical and ultrasound examination made by a cardiologist and on determination of the severity of the disease. An implantable cardioverter defibrillator (ICD) is the most effective therapy against sudden death.