Thromboelastography in patients with acute ischemic stroke.

BACKGROUND: Thromboelastography measures the dynamics of coagulation. There are limited data about thromboelastography in acute ischemic stroke other than a single study from 1974 suggesting that acute ischemic stroke patients are hypercoagulable. There have been no studies of thromboelastography in the thrombolytic era despite its potential usefulness as a measure of clot lysis. This study was designed to provide initial thromboelastography data in stroke patients before and after tissue plasminogen activator therapy and to provide the necessary preliminary data for further study of thromboelastography's ability to identify clot subtype and predict response to tissue plasminogen activator therapy. METHODS: All acute ischemic stroke patients presenting between 11/2009 and 2/2011 eligible for tissue plasminogen activator therapy were screened and 56 enrolled. Blood was drawn before (52 patients) and 10 mins after tissue plasminogen activator bolus (30 patients). Demographics, vitals, labs, 24 h National Institutes of Health Stroke Scale, and computed tomography scan results were collected. Patients were compared with normal controls. RESULTS: Acute ischemic stroke patients had shorter R (4.8 ± 1.5 vs. 6.0 ± 1.7 min, P = 0.0004), greater α Angle (65.0 ± 7.6 vs. 61.5 ± 5.9°, P = 0.01), and shorter K (1.7 ± 0.7 vs. 2.1 ± 0.7 min, P = 0.002) indicating faster clotting. Additionally, a subset formed clots with stronger platelet-fibrin matrices. Treatment with tissue plasminogen activator resulted in reduction in all indices of clot strength (LY30 = 0 (0-0.4) vs. 94.4 (15.2-95.3) P < 0.0001); however, there was considerable variability in response. CONCLUSIONS: Thromboelastography demonstrates that many acute ischemic stroke patients are hypercoaguable. Thromboelastography values reflect variable clot subtype and response to tissue plasminogen activator. Further study based on these data will determine if thromboelastography is useful for measuring the dynamic aspects of clot formation and monitoring lytic therapy.

Iodinated contrast does not alter clotting dynamics in acute ischemic stroke as measured by thromboelastography.

BACKGROUND AND PURPOSE: Iodinated contrast agents used for computed tomography angiography (CTA) may alter fibrin fiber characteristics and decrease fibrinolysis by tissue plasminogen activator (tPA). Thromboelastography (TEG) measures the dynamics of coagulation and correlates with thrombolysis in acute ischemic stroke patients. We hypothesized that receiving CTA before tPA will not impair thrombolysis as measured by TEG. METHODS: Acute ischemic stroke patients receiving 0.9 mg/kg tPA <4.5 hours of symptom onset were prospectively enrolled. For CTA, 350 mg/dL of iohexol or 320 mg/dL of iodixanol at a dose of 2.2 mL/kg was administered. TEG was measured before tPA and 10 minutes after tPA bolus. CTA timing was left to the discretion of the treating physician. RESULTS: Of 136 acute ischemic stroke patients who received tPA, 47 had CTA before tPA bolus, and 42 had either CTA after tPA and post-tPA TEG draw or no CTA (noncontrast group). Median change in clot lysis (LY30) after tPA was 95.3% in the contrast group versus 95.0% in the noncontrast group (P=0.74). Thus, tPA-induced thrombolysis did not differ between contrast and noncontrast groups. Additionally, there was no effect of contrast on any pre-tPA TEG value. CONCLUSIONS: Our data do not support an effect of iodinated contrast agents on clot formation or tPA activity.