Beta blockers after myocardial infarction: have trials changed practice?

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)

Medical management of acute myocardial infarction in Ireland: information from the Second International Study of Infarct Survival (ISIS-2)

We report the management of the 831 patients from 18 hospitals which constituted the Irish component of the 17,183 subjects enrolled in the ISIS-2 trial which studied the effects of streptokinase infusion and aspirin therapy given to patients presenting within 24 hours of the onset of suspected acute myocardial infarction. 34% of Irish patients (IP) presented for treatment within 4 hours of the development of symptoms. This compared to 44% of the overall group (OG) (p less than 0.001). This represented the lowest percentage of patients presenting within 4 hours in any of the participating countries. The mean delay time from onset of symptoms was 7.9 hours in IP compared to 6.9 in OG (p less than 0.001). The mean delay time in Ireland was longer than the mean delay time in any of the participating countries. The mean age and systolic blood pressure at presentation was similar in both groups. It was planned to treat 12% IP with aspirin compared to 10% OG (p-NS), and 71% IP with subcutaneous heparin compared with 47% OG (p less than 0.001). Intravenous heparin was planned treatment in 20% IP and 24% OG (p less than 0.01). Planned oral anticoagulant therapy was similar in both groups (p-NS). Planned use of intravenous betablockers occurred in only 2% IP and 6% OG (p less than 0.001). 9% IP and 22% OG received steroids before streptokinase infusion (p less than 0.001). 65% IP and 47% OG received subcutaneous heparin (p less than 0.001). The use of intravenous heparin and oral anticoagulants was similar in IP and OG (p-NS).(ABSTRACT TRUNCATED AT 250 WORDS)

British Heart Foundation surveys (1987 and 1989) of United Kingdom treatment policies for acute myocardial infarction

Consultant physicians and cardiologists were surveyed early in 1987 and 1989 to document the management policies for the treatment of acute myocardial infarction in United Kingdom hospitals and to assess the influence of major clinical trials on these policies. The response rate to both these surveys was high (84% (1178 physicians) in 1987 and 76% (982 physicians) in 1989). The percentage of physicians that reported using antiplatelet therapy "routinely" in acute myocardial infarction rose from 9% in 1987 to 84% in 1989 while those who reported using it "rarely or never" fell from 42% to 3%. Similarly, "routine" use of fibrinolytic therapy rose from 2% to 68%, and use "rarely or never" fell from 53% to 3%. This increase in the reported use of fibrinolytic therapy was accompanied by greater certainty about its efficacy and relative safety and by a general widening of the indications for its use. The use of other treatments in acute myocardial infarction (for example, the general use of anticoagulants, beta blockers, nitrates, calcium antagonists, or prophylactic antiarrhythmic agents) seemed to change little during this period, although the routine use of coronary angiography and oral anticoagulants after fibrinolytic therapy fell substantially between 1987 and 1989 (from 23% to 4%, and from 24% to 7% respectively). Fibrinolytic and antiplatelet therapy were accepted into the routine management of myocardial infarction during a relatively short period that coincided with the reporting of several positive controlled trial results. Clinical trials have rarely been seen to have had such a great impact on practice. In this case the rapid acceptance of the trial results may have been due to the consistency and reliability of the estimates of the size of the benefits (and risks) of therapy seen in these unusually large studies.

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The case of GISSI in changing the attitudes and practice of Italian cardiologists

This report first describes the efficiency achieved by a large scale clinical trial (GISSI), which is widely recognized as having made an important contribution to the therapy of AMI, and second emphasizes how a comprehensive research project based upon an innovative clinical trial methodology can influence the attitude and the scientific productivity of a professional community operating within a national health system. To understand the methodology of GISSI, one must appreciate both the cultural and institutional setting in which the first GISSI trial took place as well as the strong economic and scientific expectation surrounding the second GISSI trial.