The impact of new onset atrial fibrillation on mid-term cardiac mortality in patients with acute myocardial infarction

Abstract

Purpose: Although Atrial Fibrillation (AF) is commonly seen in patients with acute Myocardial Infarction (MI), clinical implications of the condition have not fully elucidated. Since transition from sinus rhythm to AF in the acute phase of MI may further deteriorate hemodynamics, the study objective was to elucidate the impact of new-onset AF on prognosis of acute MI patients. Methods: The study included 722 consecutive patients with acute MI. During index hospitalization period, AF was documented in 113 patients (AF group). The remaining 609 patients consist of non-AF group. The AF group was further divided into two groups; new-onset AF after admission (New-AF) group (n=76, 10.5%), and preexisting AF (Pre-AF) group (n=37, 5.1%). The cardiac mortality during 90 days after the onset of MI was compared among the subgroups. Results: The AF group was older and had more impaired renal function and a higher Killip class than the Non-AF group on admission. During the follow-up period, 62 patients (8.6%) died due to cardiac causes: pump failure (n=44), ventricular arrhythmias (n=9), cardiac rupture (n=8), and re-infarction (n=1). Cardiac mortality was significantly higher in AF group (n=25, 21.2%) than in Non-AF group (n=37, 6.1%) (HR of 4.0, 95% CI 2.4-6.7, p<0.001). This worse prognosis persisted regardless of the type of AF (Figure A). After adjusting other co-factors, New-AF (HR=2.3, 95% CI=1.2-4.4, p=0.013), but not Pre-AF (HR=1.4, 95% CI=0.5-3.8), remained as an independent predictor of cardiac mortality. New-AF was also disclosed to be an independent predictor of death due to pump failure (HR=2.4, 95% CI=1.1-5.0, p=0.02) (Figure B). ![Figure][1] Conclusion: New-AF may be an independent predictor of mid-term cardiac mortality, especially for pump failure death, in patients with acute MI. [1]: pending:yes