Severity of renal impairment in patients with heart failure and atrial fibrillation: implications for non‐vitamin K antagonist oral anticoagulant dose adjustment

AIMS: The non-vitamin K antagonist oral anticoagulants (NOACs) have varying degrees of renal elimination which may be challenging in patients with heart failure (HF) and atrial fibrillation (AF). We examined the severity and variation in renal impairment, and the proportion of patients requiring NOAC cessation or dose reduction. METHODS AND RESULTS: A retrospective analysis of patients with HF and AF in the Candesartan in Heart failure Assessment of Reduction in Mortality and Morbidity programme was carried out. Trends in renal impairment over 26 months were defined using Cockcroft-Gault (CG), simplified Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. Mean estimated glomerular filtration rate (eGFR) was worse at every time point in patients with AF compared with those without AF, the difference being ∼11 mL/min (CG), 9 mL/min (CKD-EPI), and 7 mL/min (MDRD). As renal function declined, CG classified a greater proportion of patients as having moderate or severe CKD and agreement with MDRD/CKD-EPI declined. At least moderate renal impairment was present in a quarter of patients with AF at baseline, a third by study completion, and approaching a half at least once during follow-up. The projected need for NOAC dose reduction was accordingly high, though it varied between individual NOACs due to different criteria for adjustment. CONCLUSIONS: Renal impairment in patients with HF and AF is common, fluctuates, progresses, and frequently mandates NOAC dose reduction, though the need for cessation is rare. Baseline renal function, the method of estimating GFR, and intensity of monitoring should be considered when commencing oral anticoagulation.