The ECG is rarely normal. It shows left atrial abnormality and left ventricular hypertrophy, with left anterior fascicular block in about 20% of patients. Septal hypertrophy may also produce nonspecific infe¬rior and apical Q waves mimicking myocardial infarction. The cardiac silhouette enlarges when ventricular systolic function deteriorates. Two-dimensional echocardiography is diagnostic, although systolic cavity obliteration and the outflow gradient may lessen with aging, ren¬dering the systolic anterior motion of the mitral valve more importani. An ambulatory ECO to document arrhythmias should probably be ob¬tained annually, because serious arrhythmias are often asymptomatic