Background: Several studies have been performed to analyze the significance of atrial fibrillation (AF) following acute myocardial infarction (AMI). In this study, we evaluated the prognostic significance of AF considering timing of its occurrence after the first AMI.
Methods- This investigation is a prospective multivariate study (cohort type); among 500 consecutive first infarct survivors who were admitted to our heart center over a 2-year period (1998-2000).
Results: Among 500 consecutive patients (pts), 66 pts (13.2%) had AF. These pts were divided into two groups A (n=36) and B (n=30), who developed AF within and after 24 hours of onset of AMI, respectively. The infarct occurred mainly (62.8%) in the proximal right coronary artery in A group (p<0.05), left ventricular ejection fraction was more decreased in B group (p<0.05); and also mitral regurgitation was more frequent in this group (p<0.05). According to multivariate analyses; older age, female sex, hypertension, ventricular hypertrophy, ventricular tachycardia, ventricular fibrillation, pericarditis, atrioventricular block (AVB) especially complete AVB, intraventricular conduction disturbance, high admission Killip class, pulmonary congestion, heart failure in hospital and 1 year follow-up mortality were higher in both groups compared to the sinus rhythm group. AF was an independent predictor of cardiac death (in-hospital and 1 year followup) in A group (odds ratio 2.29, 95% confidence interval!'1 to 4.1, p<0.05), and B group (odds ratio 4.21, 95% confidence interval 2.1 to 7.9,p<0.05), respectively.
Conclusion: The appearance of AF within or after 24 hours of first AMI is a useful parameter for evaluation of the cardiac status and prognosis of patients with AMI. We also found that emergence of AF is more common in right coronary artery lesions.