The values of TF, TFPI, and platelet aggregability in acute coronary syndromes

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Hypercoagulability is associated with expression of tissue factor (TF) in patients with acute coronary syndromes (ACS). Tissue factor pathway inhibitor (TFPI) regulates the extrinsic coagulation pathway mediated by TF.Plasma TF levels were higher in patients with ACS than in those with stable exertional angina. TF expressed on macrophages in directional coronary atherectomy specimens obtained from patients with ACS.Plasma TFPI can be separated into free TFPI and lipoprotein associated TFPI.Anticoagulant activity of lipoprotein-associated TFPI is markedly lower than free TFPI.The plasma free TFPI levels were elevated in patients with ACS.TFPI is co-localized with TF in various atherosclerotic lesions of coronary artery. In conclusion, the increase of plasma TF and TFPI levels reflects the heightened expression of TF and TFPI at unstable coronary plaques in patients with ACS.Platelet aggregability was evaluated using a new aggregometer with Iaser-light scattering which can determine the total light intensities of small, medium, and large-sized aggregates. Production of small-sized platelet aggregates were increased in patients with ACS than those with stable exertional angina. Production of medium or large-sized platelet aggregates were not increased in patients with ACS.Furthermore, increased number of small-sized platelet aggregates on admission predicted poor prognosis during in-hospital stay in patients with ACS.On the other hand, patients with unstable angina and heightened TF levels were at increased risk for unfavorable outcomes. In conclusion, the elevated plasma TF levels and small-sized platelet aggregates are associated with reccurrence of coronary events in patients with ACS.Patients with ASC who have elevated plasma TF levels or increased small-sized platelet aggregates should receive enough anti-coagulation or anti-platelet therapy to improve the levels.