摘要Background Atrial fibrillation (AF) occurs commonly in patients with acute myocardial infarction (MI) and is associated with an increased long-term mortality.This study aimed to investigate the clinical characteristics and outcomes of AF in in-hospital elderly Chinese patients with acute MI.Methods A total of 967 patients with acute MI,aged≥65 years,were categorized on the basis of the absence or presence of AF.Patients with documented AF were classified into two subgroups: the ongoing AF group and the new-onset AF group.We retrospectively evaluated the clinical profile,in-hospital outcomes,and effects of revascularization on the incidence of AF in elderly patients with acute MI.Results AF was documented in 100 (11.53%) patients and the incidence of new-onset AF was 6.51% during hospitalization.History of old MI and cerebrovascular events were more common in patients with AF than in those without AF (P<0.001,P<0.01,respectively).The incidence of AF was higher in patients with non-ST elevated MI (P=0.014),inferior wall MI (P=0.004) and cardiac function of Killip class III or IV (P=0.008).Patients with AF had more complication of pneumonia (P=0.003) and longer hospital stay.Left circumflex coronary artery involvement was more common in patients with AF (compared with patients without AF,P <0.001).Percutaneous coronary intervention or coronary artery bypass grafting significantly decreased the incidence of new-onset AF from 7.97% to 3.82% (P=0.017).AF depended to heart failure,increased the in-hospital mortality.Conclusions AF is common in elderly patients with acute MI and is associated with poorer clinical outcomes.Revascularization reduces the incidence of AF and thus improves the clinical outcomes in these patients.