Abstract 19396: Decreased Blood-Borne Tissue Factor Activity in Patients Presenting With Acute Coronary Syndrome: Should the Old Paradigm be Revisited?
Background: Exposure of vascular tissue factor (TF) is the initial event for the activation of the coagulation cascade. However, TF is also present in the circulating blood (cTF). Conflicting studies linking cTF activity and cardiovascular disease have been published. This discrepancy may be related to the use of non-validated commercial assays. We have recently reported that our immunocapture/relipidation TF assay reflects total cTF activity. Thus, we aimed at measuring cTF activity in patients with acute coronary syndrome (ACS) using our home-made assay.
Methods: Solubized TF from 480μL of plasma from aorta (Ao) and coronary sinus (Cs) of 15 patients (10 with ACS and 5 with stable angina [SA]) was captured using an anti-TF affigel complex. TF was eluted and relipidated. TF activity was assessed by adding FX (1μM), FVIIa (10nM), and CaCl2 (50mM). Every 3 min over the course of 12 min, 30μL of the reaction mixture was removed and combined with EDTA to terminate FXa generation. FXa content was determined by adding Spectrozyme-Xa (3 mM) and measuring the rate of change in absorbance at 405–490 nm. A calibration curve was derived using recombinant, lipidated TF standard. A sample of normal pooled human plasma was analyzed in parallel in each TF assay and the obtained value was treated as total TF potential (tTFp) =100%.
Results: Patients with ACS showed a significant lower cTF activity than patients with SA (89.2 vs 133.8%, p< 0.05) both in samples obtained from Ao and CS. No difference was observed between Ao and Cs in both groups.
Conclusions: Our observations show that plasma TF activity is significantly lower in patients presenting with ACS, suggesting that TF is consumed for thrombus generation and propagation.
- © 2010 by American Heart Association, Inc.