2. Patient with significant or malignant ventricular arrhythmias, defined as a patient being treated for ventricular tachycardia and/or ventricular fibrillation with an implantable cardioverter/defibrillator (ICD) or a patient being treated with Amiodarone for these same tachyarrhythmias. (Note: having an implantable cardioverter/defibrillator (ICD) per se, in a patient who does not have significant or malignant ventricular arrhythmias, does not exclude the patient from this study.)