Key result
Point-of-care PT correlates strongly with rivaroxaban anti-Xa levels post-dose in dogs.
Why the study?
The chromogenic anti-Xa assay, the gold standard for monitoring rivaroxaban, is not available as a cage-side diagnostic test for clinical use.
Do point-of-care PT and TEG correlate with anti-Xa concentrations for monitoring the anticoagulant effects of rivaroxaban in dogs?
Do point-of-care PT and TEG correlate with anti-Xa concentrations for monitoring the anticoagulant effects of rivaroxaban in dogs?
Effect estimate: R = 0.82
p-value: p=<0.001
Point-of-care PT and TEG can be practically used for therapeutic monitoring of rivaroxaban in dogs, with a 1.5-1.9x delay in PT and R values indicating therapeutic anti-Xa concentrations.
May enable point-of-care PT/TEG monitoring of rivaroxaban in dogs; leaves open prospective clinical validation.
BACKGROUND: The chromogenic anti-Xa assay, the gold standard for monitoring the anti-Xa effect of rivaroxaban, is not available as a cage-side diagnostic test for use in a clinical setting. HYPOTHESIS/OBJECTIVES: To evaluate clinical modalities for measuring the anticoagulant effects of rivaroxaban using a point-of-care prothrombin time (PT) and thromboelastography (TEG). ANIMALS: Six healthy Beagle dogs. METHODS: Prospective, experimental study. Four different doses of rivaroxaban (0.5, 1, 2, and 4 mg/kg) were administered PO to dogs. Single PO and 3 consecutive dosing regimens also were assessed. Plasma rivaroxaban concentration was determined using a chromogenic anti-Xa assay, point-of-care PT, and TEG analysis with 4 activators (RapidTEG, 1 : 100 tissue factor [TF100], 1 : 3700 tissue factor [TF3700], and kaolin), and results were compared. Spearman correlation coefficients were calculated between ratios (peak to baseline PT; peak reaction time [R] of TEG to baseline [R] of TEG) and anti-Xa concentration. RESULTS: Anti-Xa concentration had a significant correlation with point-of-care PT (R = 0.82, P < .001) and RapidTEG-TEG, TF100-TEG, and TF3700-TEG (R = 0.76, P < .001; R = 0.82, P < .001; and R = 0.83, P < .001, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: Overall, a 1.5-1.9 × delay in PT and R values of TEG 3 hours after rivaroxaban administration is required to achieve therapeutic anti-Xa concentrations of rivaroxaban in canine plasma. The R values of TEG, specifically using tissue factors (RapidTEG, TF100, TF3700) and point-of-care PT for rivaroxaban can be used practically for therapeutic monitoring of rivaroxaban in dogs.
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Bae et al. (2019) studied Healthy (n=6). Rivaroxaban vs. Baseline (pre-administration) was evaluated on Correlation between plasma anti-Xa concentration and point-of-care prothrombin time (PT) (R = 0.82, p=<0.001). Anti-Xa concentration significantly correlated with point-of-care prothrombin time (R = 0.82) and specific thromboelastography parameters 3 hours after rivaroxaban administration in dogs.
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