Approach to Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy is a genetic disease characterized by marked left ventricular (LV) hypertrophy. A dynamic LV outflow obstruction is present in approximately 20% of patients. Many affected individuals remain asymptomatic throughout life, others develop heart failure symptoms or atrial fibrillation (AF), and some die suddenly, often young and in the absence of previous symptoms. Stratification of sudden death risk is based on several markers, including a previous cardiac arrest, sustained ventricular tachycardia, family history of sudden death, extreme LV hypertrophy (>/= 30 mm), syncope, nonsustained ventricular tachycardia on Holter, and abnormal exercise blood pressure response. The implantable cardioverter-defibrillator is the most effective treatment for sudden death prevention, and should be considered in patients with either one strong or multiple risk factors. Important symptoms of heart failure develop in a minority of patients, largely as a consequence of diastolic dysfunction, and are usually treated with beta blockers, or verapamil. In patients with LV obstruction and severe symptoms unresponsive to medications, myectomy operation or alcohol septal ablation is indicated for relieving the gradient and improving quality of life. AF develops in approximately 20% of patients. Amiodarone is the most effective medication for preventing AF recurrences. In chronic AF, beta blockers or verapamil are usually effective for heart rate control. The threshold for anticoagulants is low, because even brief AF episodes have a substantial embolization risk.