Impact of oral anticoagulation in patients with atrial fibrillation at very low thromboembolic risk.

Objective: To investigate reasons for and impact of oral anticoagulation (OAC) in patients with atrial fibrillation (AF) at very low thromboembolic risk.

Methods: Individuals with CHADS-VASc score 0 (men) or 1 (women) from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) were studied. Baseline characteristics according to OAC use were evaluated by logistic regression analysis. Non-haemorrhagic stroke or systemic embolism, major bleeding, cardiovascular and all-cause mortality were compared.

Results: From 2224 low CHADS-VASc patients in GARFIELD-AF, 44% received OAC. In an adjusted model, increasing age up to 65 years (OR (95% CI)=1.31 (1.19 to 1.44)) and persistent AF (OR (95% CI)=3.25 (2.44 to 4.34)) or permanent AF (OR (95% CI)=2.29 (1.59 to 3.30)) versus paroxysmal/unclassified AF were associated with OAC use. Concomitant antiplatelet therapy (OR (95% CI)=0.21 (0.17 to 0.27)) was inversely associated. Crude incidence rates per 100 person-years over 2 years in patients on OAC versus not on OAC were 0.32 (95% CI 0.14 to 0.71) vs 0.30 (95% CI 0.14 to 0.63) for non-haemorrhagic stroke or systemic embolism, 0.21 (95% CI 0.08 to 0.57) vs 0.17 (95% CI 0.06 to 0.46) for major bleeding, 0.26 (95% CI 0.11 to 0.64) vs 0.26 (95% CI 0.12 to 0.57) for cardiovascular mortality and 0.74 (95% CI 0.44 to 1.25) vs 0.99 (95% CI 0.66 to 1.49) for all-cause mortality.

Conclusions: In contrast to guideline recommendations, almost half of real-world patients with AF at a very low thromboembolic risk according to the CHADS-VASc score receive OAC. Persistent or permanent AF and increasing age up to 65 years are associated with OAC use, while concomitant antiplatelet therapy shows an inverse association. Regardless whether patients received OAC therapy, few thromboembolic and bleeding events occur, highlighting the low risk of this population.