New‐onset atrial fibrillation in patients with acute coronary syndrome may be associated with worse prognosis and future heart failure

Abstract Background The purpose of this study was to evaluate the prognostic value of atrial fibrillation (AF) in patients with acute coronary syndrome (ACS). Methods A total 648 of consecutive ACS patients were divided into non‐AF and all‐AF groups. The all‐AF group was further subdivided into new‐onset AF and pre‐existing AF groups. We compared prognosis among these groups using the Cox regression analysis. Results The mean follow‐up period was 1.4 ± 1.2 years. Overall patient numbers were 538 in non‐AF and 110 in all‐AF groups (67 in new‐onset AF and 43 in pre‐existing AF). Seventy‐eight all‐cause deaths and 42 cardiac deaths were observed. New‐onset AF had a worse prognosis than the other groups in the Kaplan‐Meier analysis (P = 0.025) after observation. Cox regression analysis indicated no significant difference for all‐cause death among the three groups. The hazard ratio of congestive heart failure requiring hospitalization was significantly higher in the all‐AF and new‐onset AF group than in the non‐AF group. Multivariate logistic regression analysis revealed that renal dysfunction, peripheral arterial disease, Killip classification ≥2, and left ventricular ejection fraction (LVEF) were independent predictors of all‐cause death. The new‐onset AF group had the highest prevalence of Killip classification ≥2 and the lowest LVEF. Conclusion In our study, AF was not an independent predictor of all‐cause death, but new‐onset AF may be associated with worse prognosis and future heart failure.