IDENTIFICATION OF PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY AT HIGH-RISK FOR SUDDEN-DEATH

Patients with hypertrophic cardiomyopathy are at increased risk for su dden death. Recent studies have improved our ability to risk-stratify such patients and have elucidated several potential mechanisms of sudd en death and syncope. Certain noninvasive tests, such as signal-averag ed electrocardiography and measurements of cardiac autonomic function and QT/QT dispersion, are often abnormal in hypertrophic cardiomyopath y, but are not useful for risk stratification. Myocardial ischemia det ermined by exercise thallium scintigraphy, however, identifies young p atients with hypertrophic cardiomyopathy who are at high risk for card iac arrest and syncope. Nonsustained ventricular tachycardia on ambula tory Holter monitoring in the absence of symptoms of impaired consciou sness is associated with a benign prognosis and is not predictive of s udden death. Conversely, ventricular tachycardia induced at electrophy siologic study identifies adult patients with hypertrophic cardiomyopa thy who subsequently experience sudden death. Finally, characterizatio n of the natural history of the genetic defects will increasingly beco me an integral part of risk evaluation in hypertrophic cardiomyopathy.