Platelet‐mapping assay for monitoring antiplatelet therapy during mechanical circulatory support in children: A retrospective observational study

ESSENTIALS: Thromboelastography (TEG)‐platelet mapping (PM) assay is used for antiplatelet‐drug monitoring. The TEG‐PM was evaluated for dypiridamole and aspirin monitoring in 4 BH‐implanted children. Some TEG‐PM tracings were atypical leading to wrong results. The TEG‐PM has to be improved for antiplatelet‐drug monitoring during ventricular assistance. INTRODUCTION: The complex hemostatic changes associated with Berlin Heart (BH) implantation in children require a challenging antithrombotic treatment. The aim of this retrospective analysis was to evaluate the thromboelastography (TEG)‐platelet mapping (PM) assay to monitor antiplatelet therapy in children implanted with a BH. METHODS: TEG‐PM was performed in 4 BH‐implanted patients receiving dipyridamole and aspirin, and 9 healthy volunteers. Patients’ antiplatelet therapy was adjusted to TEG‐PM results. Light transmission aggregometry (LTA) was also available for 2 of these patients. RESULTS: Between 2009 and 2014, 4 BH‐implanted patients received a dual antiplatelet therapy monitored by TEG‐PM. In 2 patients, 18 of 34 tracings were atypical, because the maximum amplitude due to fibrin never stabilized, which made difficult antiplatelet therapy adjustment as recommended by BH's guidelines. To overcome this difficulty, TEG‐PM and LTA were next performed in parallel. However, both methods led to different decisions to adjust antiplatelet therapy in 57% of the cases. In order to better understand this atypical tracing, TEG‐PM was also performed in 9 volunteers and surprisingly 3 of them had the same atypical tracing. This atypical tracing was corrected by adding apyrase, suggesting that adenosine diphosphate (ADP) participates to spontaneous platelet activation in heparinized samples. In addition, we evidenced a high variability in the responses of TEG‐PM with ADP in volunteers. CONCLUSIONS: Antiplatelet therapy monitoring in BH‐implanted children remains challenging, as TEG‐PM is sensitive to several preanalytical and analytical conditions.