(P151) ANTICOAGULATION FOR ATRIAL FIBRILLATION IN PATIENTS WITH CHRONIC KIDNEY DISEASE STAGES 4 AND 5, NOT ON DIALYSIS

Background: Patients with advanced chronic kidney disease (CKD) stage 4 (eGFR = 15-29 mL/min/m2) and stage 5 (eGFR < 15 mL/min/m2) were excluded from major direct oral anticoagulants (DOAC) trials for atrial fibrillation (AF). Nevertheless, the safety and effectiveness of these agents have been shown in several large cohort studies in patients with non-valvular AF (NVAF) and stage 4/5 CKD. We aim to evaluate the use of oral anticoagulation (OAC) amongst patients with CKD stages 4 and 5 (non-dialyzed) in a large Canadian academic center.

METHODS AND RESULTS: We completed a single-center cross-sectional evaluation of patients followed at the McGill University Health Center CKD clinic in Quebec, Canada. We included patients with CKD stages 4 and 5 and excluded patients currently or imminently on dialysis (arteriovenous shunt created, peritoneal dialysis catheter installed). eGFR was calculated using the CKD-EPI formula. The most recent electrocardiograms of each patient were reviewed. We identified patients with AF based on diagnoses noted in the chart or electrocardiogram. We calculated CHADS2-65, CHA2DS2-VASc and HAS-BLED scores. We compared continuous variables with two-tailed T-test and categorical values by chi-square test. In 211 patients with CKD stages 4 and 5 (non-dialyzed), the prevalence of AF was 18% (n=38). Patients with AF were older (mean age 80.5±8.6 years), 68% were male, and the majority had CKD stage 4 (95%). Two patients had valvular AF. Of the 36 patients with NVAF, 12 (33%) were on warfarin, 20 (56%) were on DOAC, and 4 (11%) were not anticoagulated. For patients on apixaban (90% of DOAC used), 61% were on doses adherent to the Health Canada drug monograph which are based on age, weight, and serum creatinine. The patients treated with warfarin had higher mean CHA2DS2-VASc scores than patients treated with DOAC (5.8 versus 4.6; p=0.03). Patients treated with warfarin also had more cerebrovascular and peripheral vascular disease than patients on DOAC (58.3% versus 20%; p=0.03 and 50% versus 15%; p=0.03, respectively).

Conclusion: Apixaban has become the dominant OAC in our contemporary cohort of non-dialyzed patients with CKD stages 4 and 5. However, a substantial proportion of patients were on doses not adherent to the Health Canada drug monograph, non-anticoagulated or anticoagulated with warfarin. Understanding the reasons for these findings may modify AC practice, improve stroke prevention, and reduce bleeding events in this high-risk population.