- History of cardiac disease (e.g., New York Heart Association functional class II, III, or IV, myocardial infarction within the last 6 months, ventricular tachyarrhythmias requiring ongoing treatment, unstable angina, or other significant cardiovascular diseases. In addition, patients with documented or presumed coronary artery disease or cerebrovascular disease should not be enrolled if, in the judgment of the investigator, an acute decrease in hemoglobin by up to 4 g/dL (as may be seen with ribavirin therapy) would not be well tolerated.