Long-term prognosis of patients with paroxysmal atrial fibrillation complicating acute myocardial infarction. SPRINT Study Group.

The aim of the study was to assess the relationship between paroxysmal atrial fibrillation during acute myocardial infarction and the long-term prognosis of patients after acute myocardial infarction. The incidence of paroxysmal atrial fibrillation among 5803 consecutive hospitalized patients was 9.9% (557/5803). Incidence rose with increasing age (less than or equal to 59 years, 4.2%), (60-69 years, 10.5%), (greater than or equal to 70 years, 16.0%) and was slightly (but not significantly) higher in women (11.0%) than in men (9.6%). The presence of congestive heart failure and mean age represented two major discriminants between patients with paroxysmal atrial fibrillation (70% and 68.6 years) in comparison with their counterparts (35% and 62.3% years). Hospital mortality was significantly higher (25.5%) in patients with paroxysmal atrial fibrillation than in those without (16.2%). However, the effect of paroxysmal atrial fibrillation disappeared when other factors influencing the short term prognosis (i.e. heart failure) were taken into account by a multivariate logistic regression analysis. The covariate adjusted relative odds of in-hospital mortality then fell to 0.82. The 1- and 5-year mortality rates were 18.6% and 43.3% in patients with paroxysmal atrial fibrillation as compared to 8.2% and 25.4% (P less than 0.001), respectively, in patients free of paroxysmal atrial fibrillation. Using a proportional hazards analysis of mortality through the first quarter of 1988 (average follow-up time, 5.5 years) the net risk of dying among patients with paroxysmal atrial fibrillation complicating the acute myocardial infarction is estimated at 1.28 (90% confidence interval, 1.12-1.46) relative to counterparts free of the complication.(ABSTRACT TRUNCATED AT 250 WORDS)