Thrombelastograph platelet mapping in a patient receiving antiplatelet therapy

Abstract

TO THE EDITORS:We read James et al.'s 1 description of using the Thrombelastograph (TEG) PlateletMapping (PM) assay (Haemonetics Corp., Braintree, MA) to monitor and guide the antithrombotic management of a complex patient with great interest. This novel approach will be useful to physicians caring for patients with the coagulation abnormalities associated with cirrhosis in addition to pharmacological anticoagulants. However, it is being increasingly appreciated that pharmacokinetic/dynamic effects with antiplatelet therapy are relevant to the interpretation of PM results. 2In this particular case, aspirin (75 mg) and clopidogrel (75 mg) therapy was instituted with low maintenance doses. Without a loading dose and at doses lower than those used for patients undergoing procedures in the catheterization laboratory (usually 325 and 150 mg, respectively, for 5 days prior to intervention), it is not surprising that PM a week later did not show platelet inhibition (see Fig. 2A in James et al.'s article 1 ; it is not noted whether the 0% inhibition in the figure is related to arachidonic acid or an adenosine diphosphate agonist). Doubling the aspirin dose and retesting the following day would not be expected to increase inhibition significantly, although Fig. 2B in the article reveals 45% inhibition; this suggests a possible accumulation of antiplatelet effects. Although the addition of tirofiban resulted in 100% inhibition of platelet function (Fig. 2C), clinical bleeding necessitated cessation of the glycoprotein IIb/IIIa antagonist with residual 70% inhibition (Fig. 2D). On the basis of a prolonged R time suggesting impaired fibrin formation, fresh frozen plasma was administered. However, according to the TEG traces presented, the R time of 9.2 minutes was the shortest recorded in comparison with all previous traces (13-13.6 minutes). Given these data, we wonder why the authors chose fresh frozen plasma instead of a platelet transfusion, which would likely have temporarily ameliorated the platelet inhibition, the most remarkable and significant TEG finding present at that time.The authors are congratulated on their innovative use of TEG PM in a complex patient, which will stimulate further evaluation of this point-of-care monitor in patients with end-stage liver disease.

Patients with liver cirrhosis suffer from primary haemostatic defects? Fact or fiction?

“…Recently, PlateletMapping using TEG technology has been suggested as a potentially useful and novel approach to evaluate platelet function in patients with cirrhosis [53,54] (Table 1). These tests require further evaluation to verify their utility in various clinical situations.…”

Primary Hemostasis in Chronic Liver Disease and Cirrhosis: What Did We Learn over the Past Decade?

“…Soluble platelet release markers (e.g., soluble P-selectin and soluble CD40 ligand), also mainly used in research, investigate platelet activation state. PlateletMapping TEG technology employs specific platelet agonists but is mainly used for monitoring antiplatelet therapy [47].…”