Clinical impact of renal function changes in patients with atrial fibrillation receiving anticoagulation with marginal renal function

Abstract Background Renal function changes were frequently observed in patients with marginal renal function. Renal function is one of crucial components to determine the doses and types of oral anticoagulants in atrial fibrillation (AF) patients and also closely associated with the risk of stroke and bleeding. However, the incidence of renal function changes and its impact on the clinical outcomes were not well-elucidated in anticoagulated AF patients. Purpose To evaluate renal function changes during follow-up in anticoagulated AF patients with marginal renal function defined as estimated glomerular filtration rate (eGFR) 45 to 60 ml/min/1.73m2. We also analysed the association between renal function changes and clinical outcomes. Methods Using a Korean nationwide claims database, we included anticoagulated AF patients who underwent a national health examination from January 2014 to December 2018 and also had follow-up examination within 2-year. Patients with eGFR 45 to 60 ml/min/1.73m2 at baseline examination were included. Based on the follow-up eGFR values, patients were categorised into three groups according to the change in renal function: maintained group (maintaining follow-up eGFR ranges from eGFR 45 to 60 ml/min/1.73m2), improved group (eGFR 60 ml/min/1.73m2), and aggravated group (eGFR 45 ml/min/1.73m2). After follow-up examination, ischemic stroke, major bleeding, end-stage renal disease (ESRD), all-cause death, and the composite of all clinical outcomes were evaluated. Results A total of 5126 patients were included: 42.3 % of patients (n=2170) maintained their renal function at follow-up examination, renal function of 44.4 % of patients (n=2276) were improved, whereas 13.3% of patients (n=680) were aggravated at follow-up examination. The mean eGFR values at baseline of maintained, improved, and aggravated groups were 54.2±4.1, 55.5±3.7, and 52.2±4.3 ml/min/1.73m2, respectively (p0.001). The aggravated group was older, had higher CHA2DS2-VASc scores, and had more prevalent comorbidities, including hypertension, diabetes, prior myocardial infarction, and heart failure, than other groups. After multivariable adjustment, the aggravated group was associated with significantly higher risks of major bleeding, ESRD, all-cause death, and the composite outcome (HR 95% confidence interval, 1.46 1.03-2.07, p=0.035; 1.49 1.24-1.80, p0.001; 9.29 4.92-17.6, p0.001; 1.57 1.36-1.83, p0.001, respectively). Conclusion In the anticoagulated AF patients with marginal renal function, a substantial proportion of patients (13%) experienced renal function decline below eGFR 45 ml/min/1.73m2 within 2-year. Renal function decline was associated with higher risks of major bleeding, ESRD, all-cause death and the composite outcome than those maintained their baseline renal function. Performing regular check-ups of renal function and protecting renal function should be emphasised in anticoagulated patients with AF and marginal renal function.