Time trends in adherence to guideline recommendations for anticoagulation therapy in patients with atrial fibrillation and myocardial infarction.

Background: Poor adherence to guideline recommendations for anticoagulation in patients with acute myocardial infarction (MI) and atrial fibrillation (AF) is previously reported. The aim of the present cohort study was to assess time trends in prescription of anticoagulation therapy in a nationwide registry-based cohort of patients with acute MI and AF.

Methods: All patients, registered in the Norwegian Myocardial Infarction Registry (NORMI) between 2013 and 2019 with ECG-verified AF at hospitalisation, were included in the cohort study. The primary outcome was the prescription rate of anticoagulation therapy at hospital discharge and follow-up through 2019.

Results: AF was observed in 8565 (10.9% of 78369) patients registered in the NORMI from 2013 through 2019. The congestive heart failure, hypertension, age ≥75 (doubled), diabetes, stroke (doubled), vascular disease, age 65-75, and sex (female) score was ≥2 in 7845 (92%) of the hospitalised patients with AF, and in 7174 (96%) of 7440 patients discharged alive. Only 3704 (47.2%) of these patients were treated with anticoagulation prior to the MI. The prescription rate of anticoagulation therapy at discharge was 55% in 2013, increasing to 78% in 2019 (annual per cent change 6.0 (95% CI 0.7 to 11.6)). Patients prescribed anticoagulation therapy had reduced risk of all types of stroke or death at follow-up compared with patients without prescription of anticoagulation therapy (multivariate-adjusted HR 0.8, 95% CI 0.7 to 0.8, p<0.001).

Conclusions: The prescription rate of anticoagulation therapy in patients with MI and AF increased during the study period, but many patients were still undertreated with respect to stroke prevention.