NITRATES IN MYOCARDIAL-INFARCTION - INFLUENCE ON INFARCT SIZE, REPERFUSION, AND VENTRICULAR REMODELING

Objective-To assess the possible benefits of intravenous isosorbide di nitrate in acute myocardial infarction and oral isosorbide mononitrate in subacute myocardial infarction. Methods-316 patients presenting wi th acute myocardial infarction were entered into double blind placebo controlled clinical trials assessing infarct size by enzyme release, v entricular size and function by echocardiography, reperfusion by conti nuous It lead ST segment monitoring and late potentials by high resolu tion electrocardiography. Results-301 patients, of whom 292 (97%) rece ived thrombolytic treatment, were randomised on admission to intraveno us isosorbide dinitrate or placebo. Overall, there was no significant effect of treatment on infarct size, ST segment resolution, ventricula r remodelling, or late potentials at day 3. A trend was observed towar ds a reduction in infarct size in patients with non-Q wave infarction treated with isosorbide dinitrate. Heterogeneity of nitrate effect was observed in relation to the degree of ST segment elevation on present ation with a clear benefit of isosorbide dinitrate in patients with mo derate ST segment elevation (472 U/I v 704 U/l, P = 0.003) and a trend towards a deleterious effect in patients with marked ST segment eleva tion (1152 Un v 1058 Un, P = 0.2). ST segment re-elevation was more co mmon among patients receiving nitrate treatment than in those assigned to placebo (29 v 16, P < 0.05). Some 160 patients underwent a further randomisation to sustained release isosorbide mononitrate or placebo on day 3. Echocardiographic volumes after 6 weeks of treatment were si milar in the two groups. Conclusions-No benefit was observed with admi nistration of nitrates in the treatment groups as a whole for either a cute or subacute infarction. There was, however, evidence of heterogen eity of effect in the different subgroups of acute infarction, and the possibility that nitrates may have differing actions in different gro ups of patients should be considered.