- Known ejection fraction <45%, regardless of a history of heart failure. Heart failure and a history of heart failure with an ejection fraction of 40-50% may occur with a normal ejection fraction now referred to as Heart Failure With Preserved Ejection Fraction (HFpEF) or "diastolic dysfunction". A low ejection fraction is not always associated with heart failure. Our technology of measuring ejection fraction is by no means perfect. It is acceptable to use MET in larger than usual starting doses of MET for rate control or patients with "diastolic dysfunction", but not systolic dysfunction. Thus, a patient who has an ejection fraction of 42% may possibly have an ejection fraction of 37%, possible lower. Thus the investigators want to avoid the possibility of a patient with a history of heart failure does not receive MET unless the investigators feel systolic heart failure is not present.