Comparison of Dabigatran and Vitamin K Antagonists in Patients with Atrial Fibrillation in Real-World Practice

Introduction

Thromboembolic complications are the most common cause of morbidity and mortality in patients with atrial fibrillation. Although anticoagulant therapy reduces the risk of ischemic cerebrovascular accidents (strokes), there is still room for improvement in bleeding control. The introduction of direct oral anticoagulants (DOACs) into clinical practice has opened up the possibility of reducing bleeding incidents while at least comparably reducing the risk of strokes and systemic embolism. These findings from controlled studies should be complemented by data from real-world clinical practice. This is provided by the GLORIA-AF study, whose final results were published this March.

Study Methodology

GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is an international prospective non-interventional registry that included patients over 18 years of age with newly diagnosed atrial fibrillation (< 3 months) and a risk of strokes according to a CHA₂DS₂VASc score ≥ 1. The incidence of all forms of strokes (ischemic, hemorrhagic, or idiopathic), major bleeding (according to the criteria of the International Society on Thrombosis and Haemostasis /ISTH/), life-threatening bleeding, myocardial infarction (MI), overall mortality, and a composite outcome including strokes, systemic embolism, MI, cardiovascular death, and life-threatening bleeding were monitored. To compare dabigatran with VKAs, a cohort of patients with a matching propensity score was created to account for potential differences in patient characteristics between the two groups.

Results

Patients treated with dabigatran, compared to those treated with VKAs, had significantly lower risks of major bleeding (hazard ratio [HR] 0.61; 95% confidence interval [CI] 0.42-0.88) and lower overall mortality (HR 0.78; 95% CI 0.63-0.97). A non-significant reduction in the incidence of strokes (HR 0.89; 95% CI 0.59-1.34), MI (HR 0.89; 95% CI 0.53-1.48), and the composite outcome (HR 0.85; 95% CI 0.67-1.07) was observed with dabigatran compared to VKAs.

Discussion

Dabigatran and warfarin were also compared in clinical practice in two American registries. The US Medicare AF study, which included 134,414 patients with atrial fibrillation, demonstrated a lower risk of ischemic strokes, intracranial bleeding, and overall mortality with dabigatran therapy. Similar results were obtained from an analysis of data from the US Department of Defense. The risk of major bleeding was comparable in both therapeutic groups in these studies, unlike the findings from the GLORIA-AF study. This difference in safety profiles is most likely due to different dabigatran dosing, as 110 mg twice daily is not available in the USA. Lower risks of major bleeding and overall mortality with DOACs compared to warfarin were demonstrated by analyses of data from the worldwide GARFIELD-AF and ORBIT-AF registries.

Conclusion

The GLORIA-AF study is a unique study comparing the efficacy and safety of dabigatran and VKAs. It involved the largest and most diverse group of patients and had one of the longest follow-up periods of 3 years. Its results showed that patients with atrial fibrillation treated with dabigatran have a lower risk of major bleeding and lower overall mortality compared to those treated with VKAs. The incidence of strokes and MI was comparable in both groups. An undeniable advantage of this study is that the data used for the analysis come directly from clinical practice.

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Source: Huisman M. V., Teutsch C., Lu S. et al. Dabigatran versus vitamin K antagonists for atrial fibrillation in clinical practice: final outcomes from Phase III of the GLORIA-AF registry. Clin Res Cardiol 2022; 111: 548-559, doi: 10.1007/s00392-021-01957-1.