RESUMO
OBJECTIVES: This study sought to determine the incidence and significance of new-onset atrial fibrillation as a risk factor for long-term stroke and mortality after cardiac surgery. DESIGN: A prospective cohort study. SETTING: Two large tertiary public hospitals. PARTICIPANTS: The study comprised 3008 patients who underwent coronary artery bypass grafting and/or valve surgery from 2008 to 2012. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: New-onset atrial fibrillation was analyzed as a risk factor for postoperative stroke using a multivariate logistic regression model after adjustment for potential confounders. A Cox regression model with time-dependent variables was used to analyze relationships between new-onset atrial fibrillation and postoperative survival. New-onset atrial fibrillation was detected in 573 (19.0%) patients. Stroke occurred in 234 (7.8%) patients during the mean postoperative follow-up period of six ± two years. The incidence of postoperative stroke in patients with new-onset atrial fibrillation (9.9%) and patients with both preoperative and postoperative atrial fibrillation (13.8%) was higher than in patients with no atrial fibrillation (6.8%) (p = 0.002). New-onset atrial fibrillation (odds ratio, 1.53; 95% confidence interval [CI], 1.08-2.18; p = 0.017) was identified as an independent risk factor for postoperative stroke. A total of 518 (17.2%) mortalities occurred within the mean postoperative follow-up period of eight ± two years. New-onset atrial fibrillation was associated with shorter survival (hazard ratio, 1.49; 95% CI, 1.22-1.81; p < 0.001) compared with patients with no atrial fibrillation. CONCLUSIONS: New-onset atrial fibrillation is a significant risk factor for long-term stroke and mortality after cardiac surgery. Close monitoring and treatment of this condition may be necessary to reduce the risk of postoperative stroke and mortality.