- Unstable angina or myocardial infarction within 6 months prior to enrollment, New York Heart Association (NYHA) Class III or IV heart failure, uncontrolled angina, history of severe coronary artery disease, severe uncontrolled ventricular arrhythmias, sick sinus syndrome, or EKG evidence of acute ischemia or Grade 3 conduction system abnormalities unless subject has a pacemaker