Early identification of patients who may require electrical control treatment.

Patients who are at increased risk of sudden death generally have significant underlying organic heart disease, but this is not always the case. The majority of patients at risk include those with the idiopathic long QT syndrome, the Wolff-Parkinson-White disorder, mitral valve prolapse, coronary heart disease, and cardiomyopathy. A history of syncope or presyncope and/or frequent or repetitive runs of ventricular ectopic beats are common prodromal findings in patients with a potentially life-threatening problem. Potential candidates for implantable antiarrhythmic devices include high-risk patients in whom an effective antiarrhythmic agent cannot be identified or those who cannot tolerate indicated antiarrhythmic agents because of adverse side effects.