- Presence of cardiac disease including acute MI within past 6 weeks, unstable angina, uncontrolled arrhythmias causing symptoms, active endocarditis, myocarditis, or pericarditis,symptomatic aortic stenosis, uncontrolled heart failure, syncope in the past 6 weeks, severe untreated hypertension at rest (>180 mmHg systolic, >100 mmHg diastolic)