COMPARISON OF EFFICACY OF 3 AND 12 MONTHS' ANTICOAGULANT THERAPY AFTER MYOCARDIAL INFARCTION: A Controlled Clinical Trial

Abstract

In a controlled clinical trial 208 patients with myocardial infarction were randomised into two groups. The patients in group A were given anticoagulant treatment for 3 months, the patients in group B for 12 months. All the patients were under 70 years of age and had not previously had a myocardial infarction. 10 patients were withdrawn from the investigation for different reasons, leaving 101 patients in group A and 97 in group B. The comparability between the two groups was found to be good. The intensity of the treatment was moderate. The average mean prothrombin-proconvertin value per week was 24·8% in both groups in the first 3 months, and 22·4% in group B during the whole 12 months. In group A 9 patients had 11 reinfarctions, 4 sudden deaths occurred, and the mortality was 6·9%. In group B there were 5 reinfarctions, 7 sudden deaths, and a mortality of 8·3%. There were 3 extracardiac thromboembolic episodes in group A and none in group B. None of these episodes proved fatal. 1 patient died of subarachnoidal hæmorrhage. No statistically significant difference between the groups with regard to death-rate or reinfarction-rate could be demonstrated. There was no difference in the results between patients over and under 60 years of age. The investigation supports the opinion that following myocardial infarction there is no indication for anticoagulant therapy beyond the first 3 months with moderate intensity of treatment as used in this study.