4. Active Grade III-V cardiac failure as defined by the New York Heart Association Criteria. Uncontrolled angina, or MI within 6 months. Diagnosed or suspected congenital long QT syndrome. Any history of clinically significant ventricular arrhythmias (such as ventricular tachycardia, ventricular fibrillation, or Torsades de pointes). Prolonged QTc interval on pre-entry electrocardiogram (> 470 msec). Patients currently taking drugs that are generally accepted to have a risk of causing Torsades de Pointes (unless these can be changed to acceptable alternatives)