Abstract Body: Objective: Direct oral anticoagulants are Factor Xa inhibitors that are prescribed widely for both arterial and venous thromboprophylaxis. Apixaban and rivaroxaban are used interchangeably clinically but differences in their ability to inhibit thrombus formation may favor one over the other for specific clot types. However, there is a paucity of data detailing the objective differences these medications have on coagulation. Hence, this study aimed to quantify the differences between apixaban and rivaroxaban using objective viscoelastic testing (TEG) and calibrated automated thrombography (CAT) specifically in regards to thrombin generation(TG).
Methods: This was a prospective cohort study including patients with peripheral artery disease (PAD) undergoing revascularization from November 2022- February 2024. Patients were stratified based on anticoagulant therapy: rivaroxaban or apixaban. Coagulation profiles and TG in plasma were evaluated using TEG, platelet mapping (PM), and CAT from 1-month postoperative whole blood samples. Descriptive statistics were applied to characterize each group, and a Wilcox test was conducted to assess differences between rivaroxaban and apixaban groups. Pearson correlation coefficient evaluated the relationship between CAT and TEG within anticoagulant groups.
Results: A total of 25 patients were analyzed, of which 56% were on apixaban, with an average age of 72 years. All demographic variables were comparable in both groups, with no statistically significant differences. On CAT analysis, the apixaban group exhibited a higher rate of TG compared to the rivaroxaban group (66.52nM/min vs. 35.8nM/min, p=0.02). In the apixaban group, a decrease in TEG reaction time (R-time) was associated with an increase in CAT thrombin rate (p=0.04) and peak TG (p=0.04), which may imply enhanced thrombin inhibitory activity over time. Conversely, an increase in R-time was associated with an increase in the CAT thrombin lag time(p=0.02). In the rivaroxaban group, increases in the TEG adenosine diphosphate (ADP) maximum amplitude (MA) (p=0.03) and arachidonic acid(AA) MA (p<0.001) were both associated with a prolonged CAT lag time, which might suggest a prolonged clot initiation phase.
Conclusion: The apixaban group demonstrated a higher rate TG, with a decrease in R-time correlating with an increased thrombin generation rate and peak thrombin. In contrast, increases in ADP/AA MA in the rivaroxaban group were associated with a prolonged lag time.