Patients with atrial fibrillation (AF) being treated with warfarin, compared with nonvitamin K antagonist oral anticoagulants (NOACs), report significantly higher rates of cardiovascular (CV) death, ischemic stroke/transient ischemic attack/systemic embolization (IS/TIA/SE), or major bleeding (MB), regardless of SAMe-TT2R2 score. These findings were published in the journal BMC Cardiovascular Disorders.
Patients were recruited from 27 hospitals in Thailand between 2014 and 2020 into the COOL-AF Thailand (Cohort of Antithrombotic Use and Optimal International Normalized Ratio Level in Patients with Nonvalvular Atrial Fibrillation in Thailand) registry, a multicenter, prospective cohort of patients with nonvalvular AF.
A total of 3461 patients with AF were recruited into the COOL-AF Thailand registry. Of the individuals eligible for study inclusion, 2340 patients were taking warfarin and 228 were taking NOACs. The average participant age was 68.8±10.7 years. Overall, 72.5% of the patients had hypertension and 54.2% had renal disease.
Results of the study showed that, among the participants, 13.0% of those taking warfarin and 9.2% of those taking NOACs met the efficacy outcome. Additionally, 6.6% of those taking warfarin and 4.8% of those taking NOACs met the safety outcome.
Following adjustment for confounders, overall, warfarin-treated participants reported significantly more secondary outcomes compared with NOAC-treated participants (11.4% vs 7.5%, respectively; adjusted hazard ratio, 1.74; 95% CI, 1.10-2.99; P =.045), regardless of SAMe-TT2R2 score.
The most notable limitation of this study is the fact that a low event rate is reported for CV death in the warfarin group, whereas no CV death is reported in the NOAC group. Thus, a much larger study population might be needed to examine CV death more accurately as an outcome variable. Additionally, the results may not be generalizable.
“AF patients taking warfarin had a significantly higher rate of CV death or IS/TIA/SE or major bleeding compared to those taking NOACs regardless of SAMe-TT2R2 score,” the study authors wrote.
Methavigul K, Yindeengam A, Krittayaphong R. Efficacy and safety outcomes of patients with atrial fibrillation compared between warfarin and non-vitamin K antagonist oral anticoagulants based on SAMe-TT2R2 score. BMC Cardiovasc Disord. Published online January 23, 2023.1186/s12872-023-03053-w