Abstract
Background: There is no established surrogate indicator for the efficacy and safety of dabigatran. Although activated partial thromboplastin time (APTT) may be an index of safety for dabigatran, the risk factors for the development of prolonged APTT while taking dabigatran is unclear. The purpose of this study was to find risk factors contributing to prolonged APTT.
Methods and Results: 394 plasma samples from 108 patients (67±9 years of age, 70 men) with non-valvular atrial fibrillation (NVAF) at our hospital were analyzed. Median APTT in patients taking dabigatran 220 mg/day was 39.4 seconds (range 19.9-88.6), with a positive correlation between APTT and age (R2=0.04, p<0.01) and a negative correlation between APTT and creatinine clearance (Ccr) (R2=0.07, p<0.01). Median APTT in patients taking dabigatran 300 mg/day was 39.8 seconds (range 24.8-66.6), with a negative correlation between APTT and Ccr (R2=0.09, p<0.01). In multivariable analysis, significant associations were found between APTT and the following risk factors: age ≥70 years, gender, weight, Ccr, and dose of dabigatran. Twelve patients (11%) developed bleeding complication. In receiver operating characteristic analysis, the cut-off value of APTT for bleeding-related adverse effects was 50.4 seconds. In multivariate analysis, Ccr and P-glycoprotein inhibitor were significant risk factors associated with prolongation of APTT to 50 seconds.
Conclusions: We identified the risk factors contributing to prolonged APTT during dabigatran treatment in NVAF patients.
