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

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 ( = 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.