Singh, Sahib T

Introduction: Thrombo-inflammatory syndrome (TIS) characterized by a pathophysiological state of hypercoagulability, heightened platelet function, and inflammation has been observed in patients with acute myocardial infarction, and HIV. Hypothesis: The incidence of TIS is observed at a high rate in COVID-19 patients and worsens with symptom severity Methods: Blood samples from COVID-19 positive hospitalized patients (n=24) was collected for coagulation and platelet function analysis using point-of-care thromboelastography, TEG6s (Haemonetics, Corp) and routine labs were collected to measure markers of inflammation, coagulation, and organ damage (Table). Disease severity was grouped according to oxygen supplementation requirements and comparisons were made using unpaired t-test and chi-squared tests. Thrombo-inflammation was defined as the presence of both hypercoagulability by TEG [Clot initiation (R) < 4.6, fibrin clot strength (FCS) >32mm, and platelet fibrin clot strength (PFCS) >69] and D-dimer >ULN. Results: Ninety- five percent of COVID positive patients had at least one co-morbidity with the incidence of hypertension (71%), diabetes (50%), and obesity (42%) being the most frequent. A total of 63% (16/24) of patients had TIS, the incidence was significantly increased with escalating disease severity (p=0.03). A significant stepwise (p<0.05) increase in FCS, D-Dimer, WBC count, lactate dehydrogenase, and procalcitonin was observed with worsening respiratory function (table). MA-ADP a measure of platelet function was in the high normal range for 81 % of patients. Conclusions: Thrombo-inflammatory is observed with most COVID patients, importantly heightened platelet function is a component of the syndrome and raises the question if antiplatelet therapy is needed in select COVID patients. Selective assessments with TEG6s may facilitate antithrombotic personalization.

Antiplatelet agents are the standard of practice in the management of atherosclerosis and acute coronary syndrome. In contrast to the available antiplatelet agents, vorapaxar represents a novel mechanism of action. It is an antagonist of the platelet protease-activated receptor-1 and inhibits thrombin-induced and thrombin receptor agonist peptide-induced platelet aggregation. The Thrombin Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events-Thrombolysis in Myocardial Infarction 50 (TRA 2°P-TIMI 50) trial led to the approval of vorapaxar by the Food and Drug Administration and European Medicines Agency for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction (MI) or peripheral arterial disease. TRA 2°P-TIMI 50 trial showed that the use of vorapaxar (2.5 mg once/daily) in addition to standard dual antiplatelet therapy with aspirin and a P2Y12 receptor inhibitor was effective in the secondary prevention of recurrent thrombotic events among patients with previous atherothrombosis, particularly in patients with prior MI; at the expense of an increase in major bleeding. Another recently published Vorapaxar Therapy in Patients With Prior Myocardial Infarction Treated With Newer Generation P2Y12 Receptor Inhibitors Prasugrel and Ticagrelor (VORA-PRATIC) study showed that among post-MI patients treated with potent P2Y12 inhibitors (prasugrel or ticagrelor), vorapaxar reduced platelet-driven global thrombogenicity, an effect that persisted, albeit attenuated, in the absence of aspirin. The current review summarizes an up-to-date literature on pharmacokinetics, pharmacodynamics, and clinical efficacy of vorapaxar and proposes future directions of research.