- Impaired cardiac function including any one of the following: Screening ECG with a QTc > 450 msec; Patients with congenital long QT syndrome; History or presence of sustained ventricular tachycardia; Any history of ventricular fibrillation or torsades de pointes; Bradycardia defined as heart rate < 50 beats per minute (patients with a pacemaker and heart rate >= 50 beats per minute are eligible); Patients with a myocardial infarction or unstable angina within 6 months of study entry; Congestive heart failure (NY Heart Association class III or IV); Right bundle branch block and left anterior hemiblock (bifascicular block)