Although the onset of symptoms can occur at any age, typically, symptoms begin between the ages of 20 and 40. Symptoms vary but result from left ventricular outflow tract (LVOT) obstruction, diastolic dysfunction, myocardial ischemia, and supraventricular and ventricular arrhythmias. The histological features of HCM include myocyte hypertrophy and disarray, as well as interstitial fibrosis. Hypertrophy is also frequently associated with left ventricular diastolic dysfunction. In the majority of patients, HCM has a relatively benign course. However, HCM is also an important cause of sudden cardiac death, particularly in adolescents and young adults.