Abstract TMP107: Association Between Apixaban Concentration And Clinical Outcomes In Asians With Atrial Fibrillation

Abstract

Background and Purpose: Real-world data regarding apixaban concentrations are sparse. This prospective study aimed to investigate the association between apixaban concentration and thromboembolic or major bleeding events among Asians with atrial fibrillation. Methods: Atrial fibrillation patients older than 20 years, administered apixaban, and had a CHA2DS2-VASc score ≥2 points were enrolled. Peak and trough blood samples were collected to measure apixaban concentrations using ultra-high-performance liquid chromatography with tandem mass spectrometry. A Cox proportional hazard model was used to investigate the factors associated with thromboembolic or major bleeding events. Univariate followed by multivariate logistic regression analyses were performed to determine the factors associated with high or low apixaban concentrations. Results: From November 01, 2016 to February 28, 2021, 279 participants (56.3% male) were enrolled. Compared to clinical trials, 22 (7.9%) patients had trough concentration lower than the expected range, and 76 (27.2%) patients had peak concentration higher than the expected range. The average follow-up duration was 1.52±1.20 years. Low trough concentration was associated with thromboembolic events (hazard ratio [HR] and 95% confidence interval [CI], 6.75 [1.10 to 41.21]; p=0.04). Conversely, high creatinine clearance was inversely associated with thromboembolism (HR and 95% CI, 0.94 [0.90 to 1.00]; p=0.04). Off-label underdose regimen and suboptimal adherence were identified as significant factors (odds ratio and 95% CI, 4.12 [1.49 to 11.42], and 3.50 [1.11 to 11.03], respectively) for predicting lower-than-expected trough concentration. Conclusions: Thromboembolic events in apixaban therapy were associated with low trough concentrations. Further, unnecessary reduction in apixaban dose and impaired apixaban adherence predicted low trough concentrations. Measurement of apixaban concentrations may be required in certain populations.