Short- and long-term prognosis of previous and new-onset atrial fibrillation in ST-segment elevation acute myocardial infarction.

INTRODUCTION AND OBJECTIVES The impact of atrial fibrillation on the prognosis of myocardial infarction is still the subject of debate. We analyzed the influence of previous and new-onset atrial fibrillation on in-hospital and long-term prognosis in patients with acute myocardial infarction. METHODS Prospective study of 4284 patients with ST-segment elevation acute myocardial infarction. We studied all-cause in-hospital and long-term mortality (median, 7.2 years) using adjusted models. RESULTS In total, 3.2% of patients had previous atrial fibrillation and 9.8% had new-onset atrial fibrillation. In general, both groups of patients had a high baseline risk profile and an increased likelihood of in-hospital complications. The crude in-hospital mortality rate was higher in patients with previous atrial fibrillation than in those with new-onset atrial fibrillation (22% vs 12%; P<.001; 30% vs 10%; P<.001). The long-term mortality rate was 11.11/100 patient-years in patients with previous atrial fibrillation and 5.35/100 patient years in those with new-onset atrial fibrillation (both groups, P<.001). New-onset fibrillation alone (odds ratio=1.55; 95% confidence interval, 1.08-2.22) was an independent predictor of in-hospital mortality. Previous atrial fibrillation (hazard ratio=1.24; 95% confidence interval, 0.94-1.64) and new-onset atrial fibrillation (hazard ratio=0.98; 95% confidence interval, 0.80-1.21) were not independent predictors of long-term mortality. CONCLUSIONS New-onset atrial fibrillation during hospitalization is an independent risk factor for in-hospital mortality in acute myocardial infarction.