Implementation of new antithrombotic treatment strategies and outcome improvements in patients with myocardial infarction and atrial fibrillation over 20 years: a nationwide cohort study

Abstract Background Patients with myocardial infarction (MI) and concomitant atrial fibrillation (AF) present a therapeutic challenge in antithrombotic treatment. Despite new drugs and updated guidelines over two decades, their implementation and associated outcomes remain unclear. Methods We used data from the Swedish Heart Registry (SWEDEHEART) and national administrative health databases, analysing 352,822 hospital survivor cases with myocardial infarction (MI) in 2-year intervals from 2000 to 2021. Of these, 71,513 (20.3%) had concomitant atrial fibrillation (AF) and formed the main study population. Trends in antithrombotic therapy and one-year risks of outcomes were compared between the AF and non-AF populations. The primary outcome was ischaemic stroke and systemic embolism. Secondary outcomes included major bleeding and cardiovascular (CV) death. Among patients with AF, the effect of time on outcomes was evaluated using standardisation and logistic regression, accounting for differences in baseline characteristics and in-hospital treatment and discharge medication. Results Among MI cases with AF, the use of oral anticoagulants increased from 17% to 69% between 2000/01 and 2020/21, primarily driven by the adoption of direct oral anticoagulants (DOACs) in the later part of the study period. In later years, DOACs were most often used in combination with a single antiplatelet agent (Figure 1A). Among patients with AF the one-year risk of ischaemic stroke and systemic embolism declined from 5.9% in 2000/01 to 2.1% in 2020/21 (Figure 1B). Similar trends were observed for CV death, which decreased from 19.6% to 10.5%, while the risk of major bleeding increased from 3.9% in 2000/01, peaked at 7.5% in 2016/17, and then declined to 6.4% in 2020/21. Compared to MI cases without AF, the relative decline in the one-year risk of ischaemic stroke and systemic embolism, and CV death was more pronounced among those with AF (Figure 1B). Among patients with MI and AF, standardised analyses showed that most of the improvement in the one-year risk of ischaemic stroke and systemic embolism could be explained by the increased use of coronary revascularisation and the prescription of oral anticoagulants at discharge, including DOACs (Figure 2). Conclusions Oral anticoagulant use, particularly DOACs, increased in patients with MI and concomitant AF between 2000 and 2021, coinciding with reduced rates of ischaemic stroke and systemic embolism, and CV mortality. With greater utilisation of oral anticoagulants, especially in combination with antiplatelet agents, the risk of major bleeding increased. However, in recent years, the major bleeding risk has slightly declined due to a shift from triple therapy to DOAC in combination with a single antiplatelet agent. These findings highlight the impact of evolving antithrombotic strategies and the implementation of evidence-based guidelines.Figure 1 Figure 2