Platelet function testing in cardiac surgery: A comparative study of electrical impedance aggregometry and thromboelastography.

Point of care platelet function tests are increasingly used to assess drug-related platelet inhibition prior to cardiac surgery. Numerous devices are available including Thromboelastography (TEG® PlateletMapping™). The latest generation TEG® - the TEG® 6 - has recently been released incorporating a cartridge-based system with a PlateletMapping cartridge. In this study, the performance of the TEG® 6 PlateletMapping was compared to that of Multiple Electrode Aggregometry (MEA) performed with the Multiplate™. Preoperative platelet function tests were performed on 50 cardiac surgery patients. Two sets of tests were performed using arachidonic acid and ADP assessing for aspirin and ADP antagonists, respectively, assessing the MEA area under the curve (AUC) in comparison to the TEG® maximal amplitude (MA) and percentage inhibition. For both arachidonic acid and ADP, the MEA AUC did not correlate with either the TEG® MA or % inhibition by Pearson's correlation. The Bland-Altman plots, however, indicated that there might be good agreement between the tests with either reagents, accounting for the different scales of measurement.