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

Problem

Atrial fibrillation (AF) is the most common clinically significant arrhythmia in the adult population. AF is a potent risk factor for stroke and mortality; people with AF have a fivefold increased risk of stroke and a twofold increased risk of death. Anticoagulation reduces the risk of stroke (and systemic embolism) and of death at the cost of a risk of bleeding complications. Recent changes in clinical AF guidelines have broadened the scope of patients eligible for anticoagulants, however there is limited subsequent real world evidence of outcomes of patients newly diagnosed with atrial fibrillation.

Approach

GARFIELD-AF is an ongoing, observational, international registry of newly diagnosed AF patients with ≥1 additional risk factor for stroke. 51,270 participants were prospectively enrolled from 35 countries in five sequential cohorts and are being followed up for minimum of two years; UK participants were recruited in primary care. Using UK data from the GARFIELD-AF registry, we investigated the one-year event rates for all-cause mortality, stroke / systemic embolism (SE), and major bleeding in the first four cohorts. 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

2650 UK patients were enrolled between June 2010 and August 2015. At baseline, mean (SD) age was 74.4 (9.7) years and 43% were female. The mean (SD) CHA2DS2VASc and HAS-BLED scores were 3.3 (1.4) and 1.8 (0.9), respectively. 62.7% of patients were prescribed anticoagulant therapy (AC) at diagnosis (with or without an antiplatelet [AP]), 24.6% received AP only and 12.8% received neither AC nor AP. At one-year follow up, the crude events rates (95% CI) of all-cause mortality, stroke/SE and major bleeding were: 4.06 (3.35 to 4.92), 2.23 (1.72 to 2.90) and 1.15 (0.80 to 1.65) per 100 person-years, respectively. The adjusted hazards ratios (95% CI) for the UK relative to the global average across the 35 countries in GARFIELD-AF were: 0.69 (0.58 to 0.83) for all-cause mortality, 1.29 (1.04 to 1.77) for stroke/SE and 0.92 (0.64 to 1.38) for major bleeding. The rate of non-cardiovascular mortality was higher than the rate of cardiovascular mortality (1.97 vs 1.26 per 100 person-years). The most frequently recorded causes of cardiovascular deaths were: congestive heart failure (31.25%), ischemic stroke (15.63%) and myocardial infarction (12.50%).

Consequences

The most frequent major clinical outcome at one-year following diagnosis of AF was death. Mortality was driven by non-cardiovascular causes and stroke-related mortality was low, possibly due to >60% being anticoagulated following diagnosis. Nevertheless, the rate of stroke, but not major bleeding, was higher in the UK compared with global average across 35 countries; further analysis will be undertaken to elucidate the reasons for these differences.