MP-4 - GUIDELINE DIRECTED ANTICOAGULANT TREATMENT AND DOSING IN A CONTEMPORARY CANADIAN ATRIAL FIBRILLATION COHORT

Background: Current Canadian Cardiovascular Society (CCS) guidelines endorse the CHADS-65 algorithm to guide stroke/systemic embolism prevention and direct oral anticoagulant (DOAC) therapy in non-valvular atrial fibrillation (AF). However, there are a paucity of contemporary data regarding concordance of routine Canadian clinical practice with guideline recommended thromboprophylactic therapy and DOAC dosing. Accordingly, we sought to evaluate the rates and factors associated with non-guideline directed thromboprophylaxis and DOAC dosing in a Canadian AF population.

METHODS AND RESULTS: TRANSECT-AF was a registry of Canadian physicians (n=175) that reported AF cases and thromboprophylactic management (March 2021-August 2023). Patients ≥18 years old with non-valvular AF and available thromboprophylaxis data were included and categorized as guideline directed therapy (GDT) or non-guideline directed therapy (NGDT), based on concordance of their reported thromboprophylaxis with the CHADS-65 algorithm. Patients on GDT with a DOAC were then further categorized as receiving concordant or discordant dosing, based on concordance of DOAC dose with CCS guideline recommended dose. Baseline characteristics were compared between groups and multivariable logistic regression was performed to identify factors independently associated with NGDT and discordant DOAC dosing.

Of 3043 AF patients, 338 (11%) were on NGDT and 257 (76%) of these NGDT patients were not treated with anticoagulation (Table 1). Patients in the NGDT group were younger, had fewer comorbidities, higher eGFR, lower thromboembolic risk, and were more likely to be on an antiplatelet agent (Table 1). Treatment with an antiplatelet agent and higher renal function were independently associated with NGDT, while older age and prior heart failure were independently associated with GDT (Table 2A). Of the 2437 patients on GDT with a DOAC, 771 (32%) were treated with a dose that was discordant with the CCS guideline-recommendation. Patients in the discordant dosing group were older, more often female, had lower eGFR, more frequently had a prior thromboembolic event, had higher thromboembolic and bleeding risk scores, and were more often on a dose-reduced DOAC (Table 1). Relative to apixaban use, dabigatran, edoxaban or rivaroxaban use were independently associated with discordant dosing (Table 2B).


Conclusion: In this contemporary Canadian AF registry, we observed an 11% rate of non-guideline directed thromboprophylaxis and a 36% rate of guideline discordant DOAC dosing. Lower thromboembolic risk patients on antiplatelet therapy and higher thromboembolic risk patients on non-apixaban DOACs may represent target populations for quality improvement in AF antithrombotic management.