Clinical trials versus clinical practice in the secondary prevention of myocardial infarction.

To examine whether the results of trials on the secondary prevention of myocardial infarction have led to a change of prescription practice, the discharge forms of a random sample of 737 patients admitted to a university hospital with a diagnosis of acute myocardial infarction (MI) with Q wave from 1982 to 1988 were examined. Information about cardiovascular and other risk factors, contraindications, and prescription of beta-adrenoceptor antagonists (beta AA), acetylsalicylic acid (ASA) and calcium channel blockers (CCB) was collected. The prescription of these drugs was analysed in relation to clinical variables and the date of patients' discharge from hospital. During the 7 years of follow-up, the prescription of beta AA increased gradually from 20% to 30-35%; the prescription of CCB was above 30% during the same period and did not change significantly with time. The prescription of ASA increased from 0% to 30-35% in the last 3 years of follow-up. Contraindications to beta AA were present in 23.2% of cases and contraindications to ASA in 14.4%. In a multivariate analysis, hypertension (odds ratio 2.29, 95% confidence interval 1.55-3.38) and the period 1986-1988 (OR 2.27, 95% CI 1.57-3.30) were associated with the prescription of beta AA, although the prescription of beta AA decreased significantly with advancing age. Other variables inversely associated with the prescription of beta AA were contraindications (OR 0.41, 95% CI 0.24-0.66) and the presence of heart failure during admission (OR 0.08, 95% CI 0.03-0.20).(ABSTRACT TRUNCATED AT 250 WORDS)