- Impaired cardiac function including any of the following: Screening ECG with a QTc greater than 450 msec, patients with congenital long QT syndrome, history of unsustained ventricular tachycardia, any history of ventricular fibrillation or torsades de pointes, bradycardia defined as heart rate less than 50 beats per minutes, patients with a myocardial infarction or unstable angina within 6 months of study entry, congestive heart failure, right bundle branch block or left anterior hemiblock