Theophylline adenosine dipyridamole (CTAD) and citrate evaluation to survey unfractionated heparin treatment: a delayed centrifugation validation for anti-Xa measurement?

Abstract

aPTT and anti-Xa were measured in citrate and CTAD anticoagulant samples from 93 patients. Delayed centrifugation was performed in citrate samples from 31 additional patients, with hourly aPTT and anti-Xa measurement from 1 to 6 hours. In 14 of these last patients, PF4 release was also evaluated with Human CXCL4/PF4 Quantikine ELISA Kit. We observed a significant correlation between citrate and CTAD anticoagulant for aPTT (r2=0.94) and anti-Xa (r2=0.95). With Bland-Altman correlation, a minor bias was observed for anti-Xa (-0.025±0.041). Delayed centrifugation in citrated anticoagulant showed an excellent concordance from 1 to 4 hours for aPTT (-4.0±5.3 s) and anti-Xa (1.10-9±0.058 UI/mL) measurements. Moreover, PF4 release was not different between 1 hour (31.5±14.7 ng/mL) and 4 hours (33.8±11.8 ng/mL). We have demonstrated that anti-Xa measurement for unfractionated heparin should be done 4 hours in citrated plasma and that CTAD was not better than citrate. However, these initial findings require confirmation using other aPTT and calibrated anti-Xa assays.