Association between rivaroxaban and the prognosis of patients with acute myocardial infarction and new-onset atrial fibrillation

Background: New-onset atrial fibrillation (AF) in the setting of acute myocardial infarction (AMI) is associated with higher risks of stroke and mortality. However, current guidelines lack specific antithrombotic recommendations for this population. This study aimed to explore the association between rivaroxaban and the prognosis of patients with AMI and new-onset AF. Methods: This retrospective cohort study included patients with AMI and new-onset AF receiving dual antiplatelet therapy between August 2016 and June 2023 in Tianjin, China. New-onset AF (transient or nontransient) was defined as the first diagnosis of AF following AMI. The primary outcome was stroke. Results: 2477 patients were identified, including 141 rivaroxaban users and 2336 patients without oral anticoagulants (OAC). Over a median follow-up of 922 days, rivaroxaban users had a 5.7% lower risk of stroke than non-OAC users, although this was not statistically significant (19.9% vs. 25.6%; P=.152). Despite the suggestion of a protective trend, multivariable Cox regression showed that rivaroxaban use was not associated with a lower risk of stroke (hazard ratio, 0.77; 95% confidence interval, 0.52–1.13, P=.187). After propensity score matching, 155 transient (rivaroxaban: 42; non-OAC: 113) and 295 nontransient AF patients (rivaroxaban: 85; non-OAC: 210) were included. No significant association was observed between rivaroxaban and stroke, ischemic stroke, hemorrhagic stroke, all-cause mortality, cardiovascular mortality, bleeding, or major bleeding. Conclusion: No significant association was observed between rivaroxaban and clinical outcomes in patients with AMI and new-onset AF. Given the small sample size and limited statistical power, the findings are exploratory and require further validation.