3. Patients with significant cardiac illness such as symptomatic coronary artery disease or previous history of myocardial infarction, impaired left ventricle function (EF <55%) on account of any organic disease such as hypertension or valvular heart disease or serious cardiac arrhythmia requiring therapy. Patients with an electrocardiogram (EKG) disclosing an absolute QT interval >460 msec in the presence of serum potassium >/=4.0 mEq/L and magnesium >/= 1.8 mg/dL. Patients with heart rate less than 50.