5. Compromised cardiac function (left ventricular ejection fraction <55% as determined on a screening cardiac MRI or echocardiogram). Subjects may be receiving ACE (angiotensin converting enzyme) inhibitors or beta blockers, ARB (angiotensin II receptor antagonist) or aldosterone blocker/thiazide diuretic; however they must have initiated treatment more than 3 months prior to screening to ensure stable therapy.