- Unstable cardiac disease, including history of myocardial infarction within 1 year of screening, recurrent episodes of ventricular tachycardia despite appropriate medical therapy, decompensated congestive heart failure, or dilated cardiomyopathy with left ventricular ejection fraction < 40%), or a family history of Long QT Syndrome, or unexplained death in an otherwise healthy individual between the ages of 1 and 30 years.