Two year outcomes of patients with newly diagnosed atrial fibrillation: UK findings from the GARFIELD-AF registry

Problem

Atrial fibrillation (AF) increases the risk of stroke fivefold and the risk of death twofold. Anticoagulation therapy reduces the risk of stroke (and systemic embolism, SE) and death at the cost of an increased risk of bleeding. The last decade has seen the refinement of stroke and bleeding risk stratification schemes and the emergence of non-VKA anticoagulants (NOACs) which provides a wide range of anticoagulant options. These developments transformed the management of AF, however, there is limited real-world evidence of the clinical outcomes of the current management of AF.

Approach

The Global Anticoagulant Registry in the FIELD (GARFIELD-AF) registry is a prospective, observational, multi-centre, international study of patients with newly diagnosed AF with ≥1 additional risk factor for stroke. UK participants were recruited in primary care, and diagnosed with AF between 2011 and 2016. We investigated the two-year event rates for all-cause mortality, stroke/systemic embolism (SE) and major bleeding in the UK cohort. Event rates were calculated per 100 person-years of observation with corresponding 95% confidence intervals (CI); only the first occurrence of each event was taken into account.

Findings

A total of 3572 UK participants were prospectively enrolled in five sequential cohorts. At baseline, the mean age (SD) was 74.8 (9.0) years, and 41.7% of participants were females. The mean (SD) CHA2DS2VASc and HAS-BLED scores were 3.3 (1.5) and 1.6 (0.9) respectively. At diagnosis 64.7% received anticoagulant therapy (45.7% VKA and 19% NOAC, with or without an antiplatelet), 20.7% received an antiplatelet only, and 13.3% received neither anticoagulant nor antiplatelet therapy.At two-year follow up, the rates (95% CI) of all-cause mortality, stroke/SE, and major bleeding were 4.13 (3.68 to 4.65), 1.65 (1.37 to 1.99), and 0.78 (1.37 to 1.99) per 100 person-years respectively. Cardiovascular death occurred at a rate of 1.10 (0.88 to 1.39) per 100 person-years and constituted 26.7% of deaths. Non-cardiovascular death occurred at a rate of 2.15 (1.83 to 2.53) per 100 person years and constituted 52% of deaths. The remaining deaths (22.2%) were of undetermined cause. Ischemic stroke accounted for 3.2% of all known causes of death.

Consequences

In this contemporary AF study population, death remains the most frequent outcome, occurring at 2.5 times the rate of stroke/SE and over 5 times the rate of major bleeding. Compared with patients in a US AF registry (ORBIT AF) diagnosed between 2010 and 2011, our study population has a lower mortality rate (4.13 vs 5.43 per 100 person years), similar stroke rate (1.65 v 1.57 per 100 person years) and lower rate of major bleeding (0.78 vs 3.32 per 100 person-years). This suggests an improved prognosis of patients with AF with maintained clinical benefit of stroke reduction but less harm from serious bleeding.