Blood-borne tissue factor activity predicts major cerebrovascular events in patients undergoing carotid endarterectomy: results from a 1-year follow-up study

Circulating Tissue Factor Levels and Risk of Stroke

Background and Purpose—

Tissue factor (TF) expression is increased in inflammatory atherosclerotic plaques and has been related to their thrombogenicity. Blood-borne TF has been also demonstrated to contribute to thrombogenesis. However, few studies have evaluated the association of circulating levels of TF with stroke. We investigated the association of baseline circulating levels of TF with stroke events occurred in the European Prospective Investigation into Cancer and Nutrition-Italy cohort.

Methods—

Using a nested case–cohort design, a center-stratified random sample of 839 subjects (66% women; age range, 35–71 years) was selected as subcohort and compared with 292 strokes in a mean follow-up of 9 years. Blood samples were collected at baseline in citrate, plasma was stored in liquid nitrogen and TF was measured by ELISA (IMUBIND, TF ELISA, Instrumentation Laboratory, Milan, Italy). The odd ratios and 95% confidence intervals, adjusted by relevant confounders (covariates of TF) and stratified by center, were estimated by a Cox regression model using Prentice method.

Results—

Individuals in the highest compared with the lowest quartile of TF plasma levels had significantly increased risk of stroke (odds ratio IVvsI quartile , 2.01; 95% confidence interval, 1.25–3.23). The association was independent from several potential confounders (odds ratio IVvsI quartile , 1.91; 95% confidence interval, 1.15–3.19). No differences were observed between men and women. The increase in risk was restricted to ischemic strokes (odds ratio IVvsI quartile , 2.13; 95% confidence interval, 1.10–4.12; fully adjusted model), whereas high levels of TF were not associated with the risk of hemorrhagic stroke (odds ratio IVvsI quartile , 1.12; 95% confidence interval, 0.49–2.55; fully adjusted model).

Conclusions—

Our data provide evidence that elevated levels of circulating TF are potential risk factors for ischemic strokes.

Ischemic stroke predicts myocardial injury after carotid endarterectomy for symptomatic severe carotid artery stenosis

Myocardial injury following carotid endarterectomy (CEA) is a common cause of morbidity and mortality, and its risk varies depending on the severity and extent of disease. However, when patients with sympotomatic severe carotid stenosis undergo CEA, the frequency and potential predictors of myocardial injury remain unknown. A total of 40 patients (32 men and 8 women) who underwent successful standard CEA were observed. Cardiac troponin I (cTnI) concentrations were assessed before surgery and on postoperative days 1, 2, and 3 in all patients. Myocardial injury was defined as the peak cTnI concentration > 0.04 ng/mL. In all, 42.5% patients had postoperative myocardial injury. Previous ischemic stroke and abnormal ST-segment changes were the preoperative predictors of myocardial injury after CEA, with odds ratios of 4.1 (95% confidence interval, 1.1-16.1; P = .04) and 5.9 (95% confidence interval, 1.3-27.7; P = .04), respectively. Sympotomatic patients with those conditions should receive more attention to myocardial injury, when presented for CEA.

Levels of microparticle tissue factor activity correlate with coagulation activation in endotoxemic mice

BACKGROUND

Tissue factor (TF) is present in blood in various forms, including small membrane vesicles called microparticles (MPs). Elevated levels of these MPs appear to play a role in the pathogenesis of thrombosis in a variety of diseases, including sepsis.

OBJECTIVE

Measure levels of MP TF activity and activation of coagulation in control and endotoxemic mice.

MATERIALS AND METHODS

MPs were prepared from plasma by centrifugation. The procoagulant activity (PCA) of MPs was measured using a two-stage chromogenic assay. We also measured levels of thrombin-antithrombin and the number of MPs.

RESULTS

Lipopolysaccharide (LPS) increased MP PCA in wild-type mice; this PCA was significantly reduced by an anti-mouse TF antibody (1H1) but not with an anti-human TF antibody (HTF-1). Conversely, in mice expressing only human TF, MP PCA was inhibited by HTF-1 but not 1H1. MPs from wild-type mice had 6-fold higher levels of PCA using mouse factor (F)VIIa compared with human FVIIa, which is consistent with reported species-specific differences in FVIIa. Mice expressing low levels of human TF had significantly lower levels of MP TF activity and TAT than mice expressing high levels of human TF; however, there were similar levels of phosphatidylserine (PS)-positive MPs. Importantly, levels of MP TF activity in wild-type mice correlated with levels of TAT but not with PS-positive MPs in endotoxemic mice.

CONCLUSION

These results suggest that the levels of TF-positive MPs can be used as a biomarker for evaluating the risk of disseminated intravascular coagulation in endotoxemia.

Atherothrombosis and plaque heterology: different location or a unique disease?

Formation of unstable plaques frequently results in atherothrombosis, the major cause for ischaemic stroke, myocardial infarction and peripheral arterial disease. Patients who have symptomatic thrombosis in one vascular bed are at increased risk of disease in other beds. However, the development of the disease in carotid, coronary and peripheral arteries may have different pathophysiology suggesting that more complex treatment protocols may have to be designed to reduce plaque development at different locations. In this review we describe the known risk factors, compare the developmental features of coronary and carotid plaque development and determine their association with end-point ischaemic events. Differences are also seen in the genetic contribution to plaque development as well as in the deregulation of gene and protein expression and cellular signal transduction activity of active cells in regions susceptible to thrombosis. Differences between carotid and coronary artery plaque development might help to explain the differences in anatomopathological appearance and risk of rupture.