- Evidence of any known or suspected medical contraindications for use of varenicline (e.g., recent (within past two months) cardiovascular instability (including myocardial infarction or unstable angina; uncontrolled hypertension, significant neurological sequelae of cerebrovascular disease, or severe congestive heart failure (New York Heart Association class III or IV), severe chronic obstructive pulmonary disease; uncontrolled gastrointestinal, hepatic, or endocrine disease; or severe renal impairment.