- Preexisting cardiovascular disease, the only exception being well controlled essential hypertension with a sitting blood pressure of <155 systolic and <90 diastolic without any evidence of structural heart disease or one episode of myocardial infarction > 8 months ago. A past history of the any of the following are exclusions: congestive heart failure, atrial fibrillation, pulmonary hypertension, anticoagulant drug therapy, thromboembolic events, cardiomyopathy or a myocardial infarction within the past 8 months.