Impact of chronic antithrombotic therapy on hospital course of patients with acute myocardial infarction.

ABSTRACT

BACKGROUND: Little is known about the influence of chronic antithrombotic therapy on treatment and clinical outcome in patients with acute ST-elevation myocardial infarction (STEMI). HYPOTHESIS: The purpose of this study was to investigate the hospital course of STEMI patients on antithrombotics. METHODS: We analyzed data of consecutive patients with STEMI, who were prospectively enrolled in the German Acute Coronary Syndromes registry between July 2000 and November 2002. Overall, 8224 patients were stratified into 3 groups group 1 had no prior chronic antithrombotic medication (n = 6004), group 2 was on chronic acetylsalicylic acid (ASA) therapy (n = 2022), and group 3 was on chronic oral anticoagulation therapy (n = 198). RESULTS: Patients on antithrombotic medication were older and had a higher baseline risk profile. The rate of patients receiving early reperfusion (group 1 74.6%, group 2 61.2%, group 3 52.0%) and guideline-adherent adjustment therapy was lower among patients on antithrombotics. Age and left bundle branch block were strong negative predictors for early reperfusion therapy in patients with prior antithrombotic treatment. Infarct size measured by peak creatine kinase level was lower in patients on antithrombotics. Hospital mortality (group 1 8.0%, group 2 12.8%, group 3 16.2%) and major bleeding complications (group 1 1.6%, group 2 2.0%, group 3 4.1%) were highest in patients on oral anticoagulants. However, after adjustment for confounding factors, prior ASA (odds ratio [OR] 0.98, 95% confidence interval [CI] 0.80-1.21) and oral anticoagulant treatment (OR 1.06, 95% CI 0.66-1.71) were not independent predictors for in-hospital death. CONCLUSIONS: Despite a higher risk profile, patients with STEMI on a chronic antithrombotic therapy were less likely to receive early reperfusion therapy. However, after adjustment, prior ASA or oral anticoagulant therapy was not associated with higher in-hospital mortality.