1. NYHA cardiac class 3-4 heart disease as well as impaired cardiac function defined as: LVEF < 45% as determined by MUGA scan or electrocardiogram; Complete left bundle branch block; Use of cardiac pacemaker; ST depression of > 1 mm in 2 or more leads and/or T wave inversions in 2 or more continuous leads; Congenital long QT syndrome; History of, or presence of significant ventricular or atrial tachyarrhythmia's; Clinically significant resting bradycardia (< 50 bpm); QTc > 450 msec on screening ECG (using the QTcF formula);