A double-blind trial to assess long-term oral anticoagulant therapy in elderly patients after myocardial infarction. Report of the Sixty Plus Reinfarction Study Research Group.
In a randomised double-blind multicentre clinical trial the effect of continued oral anticoagulant therapy after a myocardial infarction was assessed in a group of patients over 60 years of age. Half of the 878 patients who had been on anticoagulants ever since their primary myocardial infarction received placebos instead of the anticoagulant; the others continued anticoagulant therapy. All were followed for 2 years. The levels of hypocoagulability reached in the group on anticoagulants were such that, of the registered prothrombin times ('Thrombotest'), 72% were between 107 and 180 s. 2-year total mortality was 13.4% in the placebo group and 7.6% in the group treated with anticoagulants (p = 0.017. 2-year incidence of recurrent myocardial infarction was 15.9% in the placebo group and 5.7% in the anticoagulant treated group (p = 0.0001). The incidence of intracranial events was 5.6% in the placebo group and 3.1% in the group on anticoagulants (p = 0.18). Major haemorrhagic episodes were reported by 3 placebo patients and by 27 patients treated with anticoagulants. No fatal extracranial haemorrhages were seen. In this selected group of elderly patients, continuation of intensive and stable oral anticoagulant therapy substantially reduced the risk of recurrent myocardial infarction and thereby of cardiac death.