Abstract T P57: TEG Does Not Correlate with Clot Subtype or Clinical Response to tPA

Abstract

Background: Thromboelastography (TEG) measures coagulation status in venous blood. tPA thrombolysis is affected by multiple variables including whether clots are erythrocyte or platelet-rich. We hypothesized that TEG would correlate with clot subtype and response to tPA including rapid clinical improvement (RCI), recanalization, and hemorrhagic transformation (HT). Methods: 176 acute ischemic stroke patients between 11/09 and 06/14 treated with tPA were prospectively enrolled. Venous blood for TEG was drawn before and 10 minutes after tPA bolus. Pre-tPA measures of speed and strength of clot formation (R, Delta, K, Angle, MA, and G) and post-tPA measure of clot lysis (LY30) were analyzed. Hyperdense artery (HDA) on CT was a biomarker for erythrocyte-rich clot. RCI was defined as 8 point improvement on NIHSS or total NIHSS of 0,1 at 36 hours. HT was defined as any blood on follow up imaging within 36 hours. Recanalization was defined as resolution of baseline vascular occlusion on follow up CT or MR angiogram within 36 hours. Multivariable linear regression models compared TEG parameters after adjusting for potential confounding and interactive effects. Results: No differences in pre- or post-tPA TEG were found between patients with (n=32) or without (n=102) RCI. Also, there was no correlation between TEG and HDA on CT. Clot strength was decreased in patients with recanalization (lower MA and G, p = 0.02 and p = 0.03). Clotting was slightly prolonged (longer delta, p = 0.046) in patients with HT. Discussion: Our data do not show a robust association between TEG and clot subtype or clinical response to tPA. It is likely that arterial clot lysis is determined by factors unrelated to coagulation status as measured by TEG in the venous circulation. Though we found a correlation between TEG and recanalization, the number of patients with recanalization data was too small to detect an effect on clinical outcome. Similar to our previous findings, speed of clot formation may be related to risk of bleeding. Conclusion: It is unlikely that TEG will be useful in guiding tPA therapy. Future research should focus on local arterial influences on clot lysis. Further study of TEG in hemorrhage is indicated.