Two-year outcomes of UK patients newly diagnosed with atrial fibrillation: findings from the prospective observational cohort study GARFIELD-AF

Background: Outcomes of patients newly diagnosed with atrial fibrillation (AF) in the post-vitamin K antagonist only era are not well known.

Aim: To determine the two-year outcomes of patients newly diagnosed with AF, and the effectiveness of oral anticoagulants in everyday practice.

Design & Setting: Observational prospective cohort study in UK primary care.

Method: 3574 patients aged ≥18 years with a new AF diagnosis were enrolled. We applied a propensity score using an overlap weighting scheme to obtain unbiased estimates of the treatment effect of anticoagulation vs no anticoagulation on the occurrence of death, non-haemorrhagic stroke/systemic embolism(SE) and major bleeding within 2 years of diagnosis.

Results: Overall, 65.8% received anticoagulant therapy, 20.8% received an antiplatelet only; 13.4% received neither. During the study period, the overall incidence rates (95% CI) of all-cause mortality, non-haemorrhagic stroke/SE, and major bleeding were 4.15 (3.69 to 4.66), 1.45 (1.19 to 1.77), and 1.21 (0.97 to 1.50) per 100 person-years respectively. Anticoagulation treatment compared with no anticoagulation treatment was associated with significantly lower all-cause mortality aHR 0.70 (95% CI 0.53 to 0.93), significantly lower risk of non-haemorrhagic stroke/SE (aHR 0.39 [95% CI 0.24 to 0.62]) and a non-significant higher risk of major bleeding (aHR 1.31 [(95% CI 0.77 to 2.24]).

Conclusions: Our data support a benefit of anticoagulation in reducing stroke and death, without an increased risk of a major bleed among patients with new onset AF. Anticoagulation of the group of patients at high risk of stroke not receiving anticoagulation may further improve outcomes.