Atrial Fibrillation in the Setting of Acute Myocardial Infarction: The GUSTO-I Experience fn1fn1This study was funded by grants from Genentech, South San Francisco, California; Bayer Corporation, New York, New York; CIBA-Corning, Medfield, Massachusetts; ICI Pharmaceuticals, Wilmington, Delaware; and Sanofi Pharmaceuticals, Paris, France.

OBJECTIVES: We examined the clinical predictors and angiographic and clinical outcomes associated with atrial fibrillation in the setting of acute myocardial infarction (MI). BACKGROUND: This condition has been studied primarily in prethrombolytic era small trials. METHODS: We compared baseline clinical characteristics, short-term clinical and angiographic outcomes and 1-year mortality of patients enrolled in the Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO-I) trial with atrial fibrillation on admission electrocardiography (n = 1,026 [2.5%]) or after enrollment (n = 3,254 [7.9%]) and those without atrial fibrillation (n = 36,611 [89.6%]). Univariable and multivariable analyses were used to assess relations between baseline factors and the development of atrial fibrillation. RESULTS: Patients with any atrial fibrillation more often had three-vessel coronary artery disease and initial Thrombolysis in Myocardial Infarction (TIMI) grade < 3 flow than those without the arrhythmia. In-hospital stroke was increased in patients with atrial fibrillation (3.1% vs. 1.3%, p = 0.0001), mainly ischemic stroke (1.8% vs. 0.5%, p = 0.0001). Significant multivariable predictors of later atrial fibrillation included advanced age, higher peak creatine kinase levels, worse Killip class and increased heart rate. The unadjusted mortality rate was significantly higher at 30 days (14.3% vs. 6.2%, p = 0.0001) and at 1 year (21.5% vs. 8.6%, p < 0.0001) in patients with atrial fibrillation. The adjusted 30-day mortality rate remained significantly higher with any (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.2 to 1.4) or later (OR 1.4, 95% CI 1.3 to 1.5) atrial fibrillation but not with baseline atrial fibrillation (OR 1.1, 95% CI 0.88 to 1.3). CONCLUSIONS: Atrial fibrillation in the setting of acute MI independently predicts stroke and 30-day mortality. More aggressive treatment strategies in this subgroup may be warranted and deserve further study.