Impact of atrial fibrillation and the clinical outcomes in patients with acute myocardial infarction from the K-ACTIVE registry.

Background: The clinical incidence and impact of atrial fibrillation (AF) in Japanese acute myocardial infarction (AMI) patients is not fully understood.

Methods: To elucidate the clinical incidence and impact of AF on in-hospital mortality in AMI patients, we analyzed a Japanese observational prospective multicenter registry of acute myocardial infarction (K-ACTIVE: Kanagawa ACuTe cardIoVascular rEgistry), which spans 2015 to 2019. A major adverse cardiac event (MACE) was defined as cardiovascular death, non-fatal myocardial infarction (MI), and non-fatal stroke. For assessing bleeding events, Bleeding Academic Research Consortium (BARC) type 3 or 5 was used. MACE plus BARC type 3 or 5 bleeding were considered as composite events. The clinical outcomes were followed for 1 year.

Results: The total of 5059 patients included 531 patients with AF (10.5%) and 4528 patients with sinus rhythm (SR; 89.5%). AF patients were significantly older and tended to have more comorbidities than SR patients. Oral anticoagulation therapy (OAC) was used in 44% of AF patients while single antiplatelet therapy was selected for 52% of patients with OAC. Crude in-hospital mortality was significantly greater in AF patients than in SR patients (10.4%, 5.0%, respectively, p < 0.01). The multivariate analysis was adjusted for age, sex, diabetes, hypertension, hemodialysis, smoking, previous MI, body mass index, Killip classification, out of hospital cardiac arrest, and OAC. In-hospital mortality was still significantly greater in AF patients than in SR patients in the logistic regression analysis [adjusted odds ratio 2.02 (1.31-3.14)]. AF was an independent risk factor for MACE and composite events in the Cox proportional hazards model [adjusted risk ratio (ARR) 1.91 (1.36-2.69), p < 0.01; ARR 1.72 (1.25-2.36), p < 0.01]. In contrast, AF was not an independent risk factor for bleeding [ARR 1.71 (0.79-3.71), p = 0.18].

Conclusion: In Japanese AMI patients, AF was often observed and was associated with worse MACE but not worse bleeding.