6. History of any one or more of the following cardiovascular conditions within the past 6 months: a) Cardiac angioplasty or stenting ; b) Myocardial infarction ; c) Unstable angina ; d) Coronary artery bypass graft surgery ; e) Symptomatic peripheral vascular disease ; f) Class III or IV congestive heart failure, as defined by the New York Heart Association (NYHA)