A myocardial infarction within 12 months Uncontrolled angina within 6 months Congestive heart failure within 6 months. Diagnosed or suspected congenital long QT syndrome. Any history of ventricular arrhythmias (such as ventricular tachycardia, ventricular fibrillation, or Torsades de pointes). Any history of second or third degree heart block (may be eligible if currently have a pacemaker) Heart rate <50/minute on pre-entry electrocardiogram Uncontrolled hypertension.