Study to Compare TWA Test and EPS Test for Predicting Patients at Risk for Life-threatening Heart Rhythms (ABCD Study)

The ABCD clinical study is designed to determine if a T-Wave Alternans (TWA) test is equivalent to an Electrophysiology Study (EPS) in predicting life-threatening heart rhythms in patients with ischemic heart disease, left ventricular dysfunction, and non-sustained tachycardia. Patients undergo both the TWA test and EP study and receive an Implantable Cardioverter Defibrillator (ICD)if either of the tests show the patient is at risk. The patient is then followed for 2 years. The incidence of a ventricular tachyarrhythmia events and total mortality are to be evaluated over the duration of the study.