A prospective study of estimated glomerular filtration rate and outcomes in patients with atrial fibrillation: the Loire Valley Atrial Fibrillation Project.

BACKGROUND: Atrial fibrillation (AF) is more likely to develop in patients with chronic kidney disease (CKD) than in individuals with normal renal function, and patients with CKD are more likely to suffer ischemic stroke (IS)/thromboembolism (TE). To our knowledge, no prior study has considered the impact of estimated glomerular filtration rate (eGFR) on bleeding. We investigated the relationship of eGFR to IS/TE, mortality, and bleeding in an AF population unrestricted by age or comorbidity.

METHODS: Patients with nonvalvular AF (NVAF) were stratified into five categories according to eGFR (≥ 90, 60-89, 30-59, 15-29, and < 15 mL/min/1.73 m2), analyzing risk factors, all-cause mortality, bleeding, and IS/TE. Of 8,962 eligible individuals, 5,912 had NVAF and available serum creatinine data, with 14,499 patient-years of follow-up.

RESULTS: The incidence rates of IS/TE were 7.4 and 7.2 per 1,000 person-years in individuals not receiving and receiving anticoagulation therapy, respectively. Rates of all-cause mortality were 13.4 and 9.4 per 1,000 person-years, respectively, and of major bleeding, 6.2 and 9.0 per 1,000 person-years, respectively. Rates increased with decreasing eGFR, with IS/TE rates being lower in individuals receiving oral anticoagulation (OAC) therapy. eGFR was not an independent predictor of IS/TE on multivariate analyses. When the benefit of IS reduction is balanced against the increased risk of hemorrhagic stroke, the net clinical benefit (NCB) was clearly positive in favor of OAC use.

CONCLUSIONS: Incidence rates of IS/TE, mortality, and bleeding increased with reducing eGFR across the whole range of renal function. OAC use was associated with a lower incidence of IS/TE and mortality at 1 year compared with individuals not receiving anticoagulants in all categories of renal function as measured by eGFR. The NCB balancing IS against serious bleeding was positive in favor of OAC use among patients with renal impairment.