RISK OF STROKE DURING LONG-TERM ANTICOAGULANT-THERAPY IN PATIENTS AFTER MYOCARDIAL-INFARCTION

Myocardial infarction survivors have an increased risk of stroke, whic h is reduced with long-term anticoagulant therapy. However, an estimat ed 10-times increase in risk of bleeding during such treatment has bee n reported. We evaluated the risk of stroke in patients after a myocar dial infarction and examined the relationship of the risk of intracran ial hemorrhage or cerebral infarction and the intensity of anticoagula nt therapy. The study population consisted of 3,404 post-myocardial in farction patients who took part in a randomized, double-blind, placebo -controlled trial. Patients were randomized to treatment with anticoag ulants (international normalized ratio range, 2.8-4.8) or matching pla cebo. Mean follow-up was more than 3 years. The incidence of stroke an alyzed on ''intention-to-treat'' was 0.7 per 100 patient-years in the anticoagulant patients against 1.2 in placebo, a hazard ratio of 0.60, with 95% confidence interval of 0.40 to 0.90. In the anticoagulation group, 15 patients had cerebral infarction and 17 an intracranial blee ding, 3 of which occurred after withdrawal of treatment. In the placeb o group, the numbers were 43 and 2. Of the 14 intracranial bleeds duri ng anticoagulation, 6 occurred at an international normalized ratio be tween 3.0 and 4.0 and 8 at greater than 4.0. These results confirm tha t long-term anticoagulant therapy substantially reduces the risk of st roke in postmyocardial infarction patients. The increased risk of blee ding complications associated with anticoagulant therapy is offset by a marked reduction in ischemic events. The risk of intracranial bleedi ng is directly related to the intensity of anticoagulant treatment.