- Unstable angina or myocardial infarction within 6 months prior to randomization, NYHA Class III or IV heart failure, uncontrolled angina, history of severe coronary artery disease, uncontrolled or persistent atrial fibrillation/flutter, history of ventricular fibrillation, ventricular tachycardia/torsade de pointes, sick sinus syndrome, or electrocardiographic evidence of acute ischemia or Grade 3 conduction system abnormalities unless subject has a pacemaker