- Cardiac dysfunction : LVEF <45% by echocardiography, using pacemaker,Congenital long QT syndrome or a known family history of long QT syndrome, History of or presence of clinically significant ventricular or atrial tachyarrhythmias, Clinically significant resting brachycardia (<50 beats per minute),QTc > 450 msec on baseline ECG (using the QTcF formula), Myocardial infarction within 12 months prior to starting study, Other clinically significant heart disease (e.g. unstable angina, congestive heart failure or uncontrolled hypertension).