Anticoagulation and antiplatelet strategies used in Sweden in patients with myocardial infarction and concomitant atrial fibrillation: nationwide cohort study.

BACKGROUND

Optimal antithrombotic therapy and its duration, whether triple therapy with dual antiplatelets plus oral anticoagulant (OAC), or dual antithrombotic therapy with an antiplatelet plus OAC, is uncertain for patients with myocardial infarction (MI) and atrial fibrillation (AF).

METHODS

Patients registered in SWEDEHEART (Swedish Web-system for enhancement and development of evidence-based care in heart disease evaluated according to recommended therapies) for their first MI between 2011 and 2021 with a history or new-onset AF were included (n=26 574). Linkage between SWEDEHEART and Swedish administrative health databases was performed, and pseudonymised data analysed.

RESULTS

Over time, OAC use at discharge after MI tripled from 27% in 2011 to 77% in 2021, with direct OACs (DOACs) largely replacing warfarin, predominantly in combination with a single antiplatelet. The strongest factors for initiating OAC therapy were the performance of coronary angiography (OR 1.53 (1.40-1.68)), and percutaneous coronary intervention (OR 1.49 (1.39-1.61)). However, the year of the MI was the most predictive variable associated with OAC initiation, with an OR of 9.31 (7.92-10.95) in 2021 compared with 2011. The clinical factors associated with lower likelihood of OAC initiation were dementia, liver disease, cancer and ST-elevation MI (STEMI) versus non-STEMI.

CONCLUSIONS

Use of OAC has increased over the years in patients with MI and concurrent AF, primarily driven by the increased adoption of DOACs. Additionally, there has been a shift in antithrombotic combinations, with most patients in recent years receiving DOAC in combination with a single antiplatelet, reflecting the nationwide implementation of recent evidence and guidelines. However, significant variation in antithrombotic therapy strategies remains.