Imbalance of Plasminogen Activator Inhibitor-I/ Tissue Plasminogen Activator and Tissue Factor/Tissue Factor Pathway Inhibitor in Young Japanese Men with Myocardial Infarction

Modifiable and Non-Modifiable Risk Factors for Premature Coronary Heart Disease (PCHD): Systematic Review and Meta-Analysis

AIM

We aimed to compare the prevalence of modifiable and non-modifiable coronary heart disease (CHD) risk factors among those with premature CHD and healthy individuals.

METHODS

PubMed, CINAHL, Embase, and Web of Science databases were searched (review protocol is registered in PROSPERO CRD42020173216). The quality of studies was assessed using the National Heart, Lung and Blood Institute tool for cross-sectional, cohort and case-control studies. Meta-analyses were performed using Review Manager 5.3. Effect sizes for categorical and continuous variables, odds ratio (OR) and mean differences (MD)/standardised mean differences (SMD) with 95% confidence intervals (CI) were reported.

RESULTS

A total of n=208 primary studies were included in this review. Individuals presenting with premature CHD (PCHD, age ≤65 years) had higher mean body mass index (MD 0.54 kg/m2, 95% CI 0.24, 0.83), total cholesterol (SMD 0.27, 95% CI 0.17, 0.38), triglycerides (SMD 0.50, 95% CI 0.41, 0.60) and lower high-density lipoprotein cholesterol (SMD 0.79, 95% CI: -0.91, -0.68) compared with healthy individuals. Individuals presenting with PCHD were more likely to be smokers (OR 2.88, 95% CI 2.51, 3.31), consumed excessive alcohol (OR 1.40, 95% CI 1.05, 1.86), had higher mean lipoprotein (a) levels (SMD 0.41, 95% CI 0.28, 0.54), and had a positive family history of CHD (OR 3.65, 95% CI 2.87, 4.66) compared with healthy individuals. Also, they were more likely to be obese (OR 1.59, 95% CI 1.32, 1.91), and to have had dyslipidaemia (OR 2.74, 95% CI 2.18, 3.45), hypertension (OR 2.80, 95% CI 2.28, 3.45), and type 2 diabetes mellitus (OR 2.93, 95% CI 2.50, 3.45) compared with healthy individuals.

CONCLUSION

This meta-analysis confirms current knowledge of risk factors for PCHD, and identifying these early may reduce CHD in young adults.

Plasma tissue factor coagulation activity in post-acute myocardial infarction patients

INTRODUCTION

Coagulation is involved in fibroproliferative responses following acute myocardial infarction (AMI). Left ventricular (LV) remodeling following AMI is closely associated with progression to heart failure. This study aims to assess the association between plasma tissue factor activity and LV remodeling in post-AMI patients.

METHODS

We studied 228 patients with AMI and 57 healthy subjects. Patients with AMI were categorized into two age- and sex-matched groups: patients with adverse LV remodeling or reverse LV remodeling, defined by an increase or decrease, respectively, in LV end systolic volume by ≥15% over 6 months. TF activity was measured in plasma collected at baseline (within 72 hours of revascularization), 1 month and 6 months post-AMI. Multiple level longitudinal data analysis with structural equation (ML-SEM) model was used to assess the impact of various clinical variables on TF activity in post-AMI.

RESULTS

Plasma TF activity in post-AMI patients at baseline (29.05 ± 10.75 pM) was similar to that in healthy subjects but fell at 1 month (21.78 ± 8.23, p<0.001) with partial recovery by 6 months (25.84 ± 8.80, p<0.001) after AMI. Plasma TF activity at 6 month post-AMI was better restored in patients with reverse LV remodeling than those with adverse LV remodeling (27.35 ± 7.14 vs 24.34 ± 9.99; p=0.009) independent of gender, age and relevant cardiovascular risk factors.

CONCLUSIONS

Plasma TF activity decreased after AMI but was better restored at 6 months in patients with reverse LV remodeling. The clinical significance of changes in post-AMI plasma TF activity needs further investigation.

Biomarkers of coagulation and fibrinolysis in acute myocardial infarction: a joint position paper of the Association for Acute CardioVascular Care and the European Society of Cardiology Working Group on Thrombosis

The formation of a thrombus in an epicardial artery may result in an acute myocardial infarction (AMI). Despite major advances in acute treatment using network approaches to allocate patients to timely reperfusion and optimal antithrombotic treatment, patients remain at high risk for thrombotic complications. Ongoing activation of the coagulation system as well as thrombin-mediated platelet activation may both play a crucial role in this context. Whether measurement of circulating biomarkers of coagulation and fibrinolysis could be useful for risk stratification in secondary prevention is currently not fully understood. In addition, measurement of such biomarkers could be helpful to identify thrombus formation as the leading mechanism for AMI. The introduction of biomarkers of myocardial injury such as high-sensitivity cardiac troponins made rule-out of AMI even more precise. However, elevated markers of myocardial injury cannot provide proof of a type 1 AMI, let alone thrombus formation. The combined measurement of markers of myocardial injury with biomarkers reflecting ongoing thrombus formation might be helpful for the fast and correct diagnosis of an atherothrombotic type 1 AMI. This position paper gives an overview of the current knowledge and possible role of biomarkers of coagulation and fibrinolysis for the diagnosis of AMI, risk stratification, and individualized treatment strategies in patients with AMI.

Thrombotic/Thrombolytic Balance as a Cardiac Treatment Determinant in Patients With Diabetes Mellitus and Coronary Artery Disease

Background

This study aimed to assess whether the plasminogen activator inhibitor‐1/tissue plasminogen activator (PAI‐1/tPA) ratio as a prothrombotic state is useful for optimizing cardiac treatment strategy.

Methods and Results

Using BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial data, we used a Cox proportional hazard model to calculate hazard ratios with 95% CIs for cardiac events in patients receiving early revascularization (percutaneous coronary intervention or coronary artery bypass grafting) or medical therapy, separately in patients with low (n=1276) and high (n=894) PAI‐1/tPA ratios. The primary outcome was major cardiac events, which was a composite end point including cardiac death and nonfatal myocardial infarction. The mean±SD follow‐up period was 4.1±1.7 years. The risk of major cardiac events in patients with high PAI‐1/tPA ratio was significantly higher when receiving percutaneous coronary intervention (hazard ratio, 1.84; 95% CI, 1.16–2.93; P=0.01) than when receiving medical therapy, whereas that in patients with low PAI‐1/tPA ratio did not differ significantly between the groups (hazard ratio, 0.95; 95% CI, 0.66–1.36; P=0.77); the interaction between the cardiac treatment strategy and PAI‐1/tPA ratio was significant (P=0.02). However, regardless of the PAI‐1/tPA ratio, major cardiac event risk seemed to be lower in patients receiving coronary artery bypass grafting than in those receiving medical therapy.

Conclusions

In patients with type 2 diabetes mellitus and coronary artery disease, this study demonstrated that those with high PAI‐1/tPA ratio were at higher risks of major cardiac events when treated with percutaneous coronary intervention than when treated with intensive medical therapy.

Tissue factor-bearing microparticles and inflammation: a potential mechanism for the development of venous thromboembolism in cancer

Cancer is associated with an increased risk of venous thromboembolism (VTE); the exact mechanisms for the induction of VTE remain to be fully elucidated, but it is widely acknowledged that tissue factor (TF)-bearing microparticles (TF-MPs) may play a significant role. However, TF-MPs have yet to be accepted as a genuine biomarker for cancer-associated VTE, as the presence of elevated TF-MP levels is not always accompanied by thrombosis; interestingly, in certain cases, particularly in pancreatic cancer, VTE seems to be more likely in the context of acute inflammation. Although several potential mechanisms for the development of VTE in cancer have been postulated, this review explores the homeostatic disruption of TF-MPs, as the main reservoir of bloodborne TF, in the context of cancer and inflammation, and considers the abrogated responses of the activated endothelium and mononuclear phagocyte system in mediating this disruption.

Pro-coagulant activity during exercise testing in patients with coronary artery disease

Background

Strenuous exercise may trigger myocardial infarction through increased pro-coagulant activity. We aimed to investigate whether patients referred for exercise testing, who were found to have angiographically verified coronary artery disease (CAD), have a more hypercoagulable profile during exercise testing than those without CAD.

Methods

Patients with symptoms of stable CAD were examined with exercise electrocardiography on bicycle ergometer. Venous blood samples were taken at rest and within 5 min after end of exercise. The following haemostatic variables were analyzed: tissue factor pathway inhibitor (TFPI) activity and antigen, prothrombin fragment 1 + 2 (F1 + 2), D-dimer and endogenous thrombin potential (ETP). All participants underwent conventional coronary angiography. CAD was defined as having any degree of atherosclerosis.

Results

Out of the 106 patients enrolled, 70 were found to have CAD. Mean exercise duration was 10:06 ± 4:11 min, with no significant differences between the groups. A significant increase from baseline to after exercise testing was observed in all measured markers in the total population (p ≤ 0.002 for all). In patients with angiographically verified CAD, total TFPI was significantly lower at baseline compared to patients without CAD (median value 67.4 and 76.6 ng/ml respectively, p = 0.027). However, no significant differences in changes of any of the measured markers during exercise were observed between the two groups.

Conclusion

Pro-coagulant activity increased during short-term strenuous exercise testing in patients with symptoms suggestive of CAD. However the hypercoagulable state observed, was not more pronounced in patients with angiographically verified CAD compared to patients without CAD. NCT01495091.

The role of tissue factor pathway inhibitor in atherosclerosis and arterial thrombosis

Tissue factor pathway inhibitor (TFPI) is the main inhibitor of tissue factor (TF)-mediated coagulation. In atherosclerotic plaques TFPI co-localizes with TF, where it is believed to play an important role in attenuating TF activity. Findings in animal models such as TFPI knockout models and gene transfer models are consistent on the role of TFPI in arterial thrombosis as they reveal an active role for TFPI in attenuating arterial thrombus formation. In addition, ample experimental evidence exists indicating that TFPI has inhibitory effects on both smooth muscle cell migration and proliferation, both which are recognized as important pathological features in atherosclerosis development. Nonetheless, the clinical relevance of these antithrombotic and atheroprotective effects remains unclear. Paradoxically, the majority of clinical studies find increased instead of decreased TFPI antigen and activity levels in atherothrombotic disease, particularly in atherosclerosis and coronary artery disease (CAD). Increased TFPI levels in cardiovascular disease might result from complex interactions with established cardiovascular risk factors, such as hypercholesterolemia, diabetes and smoking. Moreover, it is postulated that increased TFPI levels reflect either the amount of endothelial perturbation and platelet activation, or a compensatory mechanism for the increased procoagulant state observed in cardiovascular disease. In all, the prognostic value of plasma TFPI in cardiovascular disease remains to be established. The current review focuses on TFPI in clinical studies of asymptomatic and symptomatic atherosclerosis, coronary artery disease and ischemic stroke, and discusses potential atheroprotective actions of TFPI.

Coagulation and fibrinolysis in diabetes

Atherothrombotic complications are the main cause of mortality in subjects with diabetes. Premature atherosclerosis, increased platelet reactivity and activation of coagulation factors with associated hypofibrinolysis all contribute to increased cardiovascular risk in this population. Blood clot formation represents the last step in the atherothrombotic process, and the structure of the fibrin network has a role in determining predisposition to cardiovascular disease. In this review, we discuss alterations in coagulation factor plasma levels and/or activity in diabetes and clarify their role in predisposition to cardiovascular events. The effect of diabetes on fibrin network structure/fibrinolysis is reviewed and potential mechanisms that modify clot properties are discussed. Finally, modulation of clotting potential by the various therapeutic agents used in diabetes is examined. Understanding the mechanisms by which diabetes influences the coagulation pathway will help to develop more effective treatment strategies to reduce thrombotic events in subjects with this condition.

Tissue factor-induced thrombin generation in the fasting and postprandial state among elderly survivors of myocardial infarction

INTRODUCTION

Tissue factor (TF)-induced thrombin generation (TG) ex vivo has been suggested to be an important method to assess thrombotic risk. No studies have investigated the impact of postprandial lipemia on TF-induced TG. Since myocardial infarction (MI) is associated with elevated postprandial levels of triglycerides, we hypothesized a differential impact of postprandial lipemia on coagulation activation in MI-patients and healthy controls.

MATERIAL AND METHODS

Elderly survivors of acute MI (n=44) and healthy age-and sex matched controls (n=43) underwent a fat tolerance test (1 gram per kg body weight) to assess coagulation activation during postprandial lipemia.

RESULTS

The incremental area under the curve (AUCi) for serum triglycerides was higher in MI-patients than in healthy age-and sex matched controls (5.64±0.52 mmol/L*h and 3.94±0.39 mmol/L*h, p=0.012) during the postprandial phase. Subsequent endogenous activation of coagulation, assessed by FVIIa and thrombin generation (F1+2), was similar among groups and not related to levels of triglycerides during the postprandial phase. Healthy individuals had a gradual decline in TF-induced thrombin generation ex vivo, assessed by endogenous thrombin potential (ETP) (AUCi=-542.4±71.4 nM*min*h, p<0.001), whereas MI-patients retained their ETP (AUCi=127.4±89.0 nM*min*h, p=0.47) in plasma during the postprandial phase (p for group difference=0.005).

CONCLUSIONS

MI-patients had elevated postprandial lipemia and retained their ability for TF-induced TG in plasma ex vivo in the postprandial phase, whereas the capacity gradually decreased in healthy individuals. Further studies are warranted to reveal underlying mechanism(s) and clinical implications.

Intracoronary β‐irradiation enhances balloon‐injury‐induced tissue factor expression in the porcine injury model

Intracoronary brachytherapy (ICBT) effectively reduces restenosis but is associated with late thrombosis. Since tissue factor (TF) is an important mediator of arterial thrombosis, we tested the hypothesis that ICBT results in persistently augmented TF expression. Coronary arteries from 12 pigs were randomized to: control (C; no injury), oversized balloon injury (BI), or BI followed by ICBT. Animals were sacrificed at 1, 7, 14, or 60 days postprocedure, and coronary arteries collected for expression analyses and immunostaining. ICBT-treated arteries had higher TF antigen and activity at all time-points compared to BI arteries (Western blot: 16 571 +/- 2090 vs 10 135 +/- 2939 densitometric units, p = 0.001; ELISA: 0.42 +/- 0.13 nM vs 0.25 +/- 0.14 nM, p = 0.001; TF activity assay: 0.303 +/- 0.11 nM vs 0.18 +/- 0.07 nM, p = 0.01; immunohistochemical staining: 30.6 +/- 6.6% vs 11.5% +/- 3.2%, p = 0.01). TF expression increased following BI, increased further following ICBT, and persisted for the duration of the study. We conclude that TF expression increases after BI, but is further increased and persists for a longer duration following ICBT, suggesting that a TF-mediated mechanism may play a role in late thrombosis following ICBT.

Cardiovascular disease and heritability of the prothrombotic state

Atherothrombotic disease remains a major cause of mortality worldwide, and family clustering suggests an important contribution of genetic factors to disease pathogenesis. Thrombus formation represents the final step in atherothrombosis, a process influenced by genetic and environmental factors. A major difficulty of investigating the genetic regulation of thrombotic conditions is the complexity of the phenotype and the relatively modest effects of individual genetic variations. We address in this review genetic aspects involved in regulating thrombosis potential and their impact on the development of atherothrombotic disease. The effects of common genetic polymorphisms in clotting factors are discussed and examples of complex gene-gene and gene-environment interactions are highlighted. Understanding the effects of genetic factors on predisposition to thrombotic disease and unravelling the complex gene-environment interactions will help to better understand the pathophysiology of this complex condition, which will enable the development of new preventative and treatment strategies.

Modulation of serpin reaction through stabilization of transient intermediate by ligands bound to alpha-helix F

Mechanism-based inhibition of proteinases by serpins involves enzyme acylation and fast insertion of the reactive center loop (RCL) into the central beta-sheet of the serpin, resulting in mechanical inactivation of the proteinase. We examined the effects of ligands specific to alpha-helix F (alphaHF) of plasminogen activator inhibitor-1 (PAI-1) on the stoichiometry of inhibition (SI) and limiting rate constant (k(lim)) of RCL insertion for reactions with beta-trypsin, tissue-type plasminogen activator (tPA), and urokinase. The somatomedin B domain of vitronectin (SMBD) did not affect SI for any proteinase or k(lim) for tPA but decreased the k(lim) for beta-trypsin. In contrast to SMBD, monoclonal antibodies MA-55F4C12 and MA-33H1F7, the epitopes of which are located at the opposite side of alphaHF, decreased k(lim) and increased SI for every enzyme. These effects were enhanced in the presence of SMBD. RCL insertion for beta-trypsin and tPA is limited by different subsequent steps of PAI-1 mechanism as follows: enzyme acylation and formation of a loop-displaced acyl complex (LDA), respectively. Stabilization of LDA through the disruption of the exosite interactions between PAI-1 and tPA induced an increase in the k(lim) but did not affect the SI. Thus it is unlikely that LDA contributes significantly to the outcome of the serpin reaction. These results demonstrate that the rate of RCL insertion is not necessarily correlated with SI and indicate that an intermediate, different from LDA, which forms during the late steps of PAI-1 mechanism, and could be stabilized by ligands specific to alphaHF, controls bifurcation between the inhibitory and the substrate pathways.

Glucagon as a determinant of fibrinolytic activity in men with different stages of glucose tolerance: impact of glucagon on fibrinolysis

Glucagon plays an important role in postprandial hyperglycemia in type 2 diabetes (T2DM), and coexists with insulin resistance and impaired fibrinolysis. We analyzed the response of plasminogen activator inhibitor-1 (PAI-1) to a lipid-glucose-protein test and the relationship between glucagon and PAI-1, tissue plasminogen activator (t-PA) and PAI-1/t-PA in 26 men with normal glucose tolerance (NGT), nine with impaired glucose tolerance (IGT) and 12 with T2DM. Fasting and postprandial PAI-1 were higher in T2DM versus NGT (P < 0.05). In univariate analysis in NGT, fasting and area under the curve (AUC) PAI-1 showed a strong relationship with fasting (P = 0.003, P = 0.006) and postprandial (P = 0.041, P = 0.045) glucagon, t-PA with fasting glucagon (P = 0.014), and PAI-1/t-PA with fasting (P = 0.047) and AUC glucagon (P = 0.017). In IGT fasting, AUC PAI-1 and PAI-1/t-PA were associated with AUC glucagon (P = 0.035, P = 0.032, P = 0.023). In NGT with the fasting metabolic parameters and insulin resistance as independent variables, fasting glucagon remained an independent covariate for PAI-1 and PAI-1/t-PA. In another model, postprandial glucagon was independently associated with PAI-1/t-PA in NGT (P < 0.05). Besides the already established determinants, we found an independent association between glucagon and fibrinolysis in NGT. Further studies are needed to identify the link between glucagon, insulin resistance and hemostasis.

Tissue factor and urokinase-type plasminogen activator system are related to the presence of cardiovascular disease in hemodialysis patients

INTRODUCTION

The disturbances of haemostasis and enhanced oxidative stress (SOX) appear to contribute to the cardiovascular disease (CVD) in hemodialysis (HD) patients. The aim of the present study was to investigate if the disorders of coagulation/fibrinolysis system are associated with the presence of CVD in these patients.

MATERIALS AND METHODS

We compared pre-dialysis levels of uPA, suPAR, tissue factor (TF) and its inhibitor (TFPI), prothrombin fragment F1+2 (F1+2); a marker of SOX-Cu/Zn superoxide dismutase (Cu/Zn SOD) and a surrogate of inflammation-high sensitivity C-reactive protein (hs CRP) in HD patients with and without CVD.

RESULTS

The uPA/suPAR system and hs CRP values were significantly greater in patients with CVD than in those without CVD; whereas TF, TFPI, F1+2 and Cu/Zn SOD levels were comparable in both patient groups. TF was positively correlated with both uPA (p<0.001) and suPAR levels (p<0.05). Logistic regression analysis showed that elevated levels of suPAR, TF and uPA were independently associated with the presence of CVD in HD patients.

CONCLUSIONS

The association between TF and uPA/suPAR system is significantly related to the presence of CVD in HD patients.

Coagulation and atherothrombotic disease

Atherothrombotic disease arises secondary to a complex gene-environment interaction. In the initial stages, the condition is clinically silent but with more advanced disease, an occlusive thrombus is formed resulting in the classical clinical manifestations. Both environmental factors and genetic variations in elements of the clotting cascade influence thrombosis risk by inducing quantitative and qualitative changes in the mature protein, which may affect the final structure of the clot and determine its resistance to lysis. Understanding the fine details of gene-environment interactions in relation to thrombus formation will help to shed more light on disease pathogenesis. Consequently, this will allow the development of more efficacious treatment strategies and will also help to identify subjects at risk, thereby enabling the introduction of early preventative measures.

Soluble fibrin, C-reactive protein, fibrinogen, factor VII, antithrombin, proteins C and S, tissue factor, D-dimer, and prothrombin fragment 1 + 2 in men with acute myocardial infarction </=45 years of age

To evaluate the contribution of hematologic factors and long-term inflammation to the development of myocardial infarction at a young age, we measured hematologic variables, including soluble fibrin and high-sensitivity C-reactive protein, in 90 patients who had myocardial infarction and 138 controls </=45 years of age. Plasma levels of soluble fibrin and C-reactive protein were significantly higher in patients than in controls. On multivariate regression analysis, soluble fibrin was the strongest predictor of myocardial infarction at a young age.

Role of thrombotic and fibrinolytic factors in acute coronary syndromes

There is a growing body of literature concerning the contribution of hemostatic factors to the development of cardiovascular disease. The mechanisms of the coagulation/fibrinolytic system are complicated and one factor is intimately interrelated with another; thus the contribution of each factor cannot be clearly understood, unless hemostatic factors are considered in accordance with endothelial function and vessel morphology. Although there are many clinical studies about the correlation between hemostatic factors and cardiovascular risk, the results are inconsistent and conflicting at times. Fibrinogen and D-dimer are associated with atherosclerosis or coronary events across multiple studies, even after multivariate adjustment. But the hemostatic factors are intimately correlated, so it can be said that focusing on one to the exclusion of others is inappropriate. The clinical trials with statins or angiotensin converting enzyme inhibitors have shown favorable effects on the prognosis of cardiovascular disease. The study of hemostatic factors in relation to these drugs has provided insights into understanding how these drugs produce beneficial effects.

R353Q Polymorphism, Activated Factor VII, and Risk of Premature Myocardial Infarction in Japanese Men

BACKGROUND

The association between myocardial infarction (MI) and the R353Q polymorphism of the Factor VII (FVII) gene, which reportedly influences FVII concentrations, activated Factor VII (FVIIa), or FVII antigen (FVIIag), remains controversial.

METHODS AND RESULTS

The present case - control study in 127 Japanese men with their first MI at or before 45 years of age and 150 matched healthy controls was designed to clarify this association in premature MI. R353Q polymorphism was determined by polymerase chain reaction, and plasma concentrations of FVIIa and FVIIag were assayed. The distribution of the RR, RQ, and QQ genotypes with respect to R353Q polymorphism was 117, 10, and 0 in the patients, and 131, 17, and 2 in the controls. The Q allele was negatively associated with premature MI (odds ratio =0.41, p=0.038). The plasma concentration of FVIIa was slightly higher in patients (55.1+/-40.9 U/L) than in controls (44.8+/-20.2 U/L), but not significantly (p=0.078); the plasma concentration of FVIIag did not differ between patients (88.7+/-15.7%) and controls (87.0+/-9.0%) (p=0.557). Plasma FVIIa concentrations were influenced by R353Q polymorphism (p<0.001).

CONCLUSIONS

The Q allele may be protective against premature MI.

Homocysteine and hemostatic disorder as a risk factor for myocardial infarction at a young age

INTRODUCTION

Hyperhomocysteinemia is a coronary risk factor, but its pathophysiologic mechanism remains unclear.

MATERIALS AND METHODS

The importance of hyperhomocysteinemia in the pathogenesis of early myocardial infarction, was determined in case-control study of 127 men with a first early myocardial infarction <or=45 years and 150 age-matched male controls. We measured plasma concentrations of homocysteine, fibrinogen, antithrombin, tissue factor, tissue factor pathway inhibitor, tissue plasminogen activator, plasminogen activator inhibitor-I, plasminogen, alpha(2)-antiplasmin, lipoprotein(a), protein C, protein S, factor VII, and activated factor VII.

RESULTS

Homocysteine concentrations were higher in patients with early myocardial infarction than in controls (11.2+/-5.3 and 8.3+/-5.0 micromol/l, respectively, P<0.001). Hyperhomocysteinemia was associated with early myocardial infarction (odds ratio=2.22, P<0.001) by multivariate logistic regression analysis. Tissue factor, antithrombin, plasminogen, tissue plasminogen activator, plasminogen activator inhibitor-I, lipoprotein(a), diabetes, and smoking also had associations. In a stepwise logistic regression analysis, hyperhomocysteinemia was the strongest predictor of early myocardial infarction (R(2)=0.19, P<0.001). Hyperhomocysteinemia also had positive correlations with tissue factor (rho=0.26, P=0.009), tissue factor pathway inhibitor (rho=0.23, P=0.020), and tissue plasminogen activator (rho=0.25, P=0.011) in patients with early myocardial infarction, but not in controls.

CONCLUSIONS

Hyperhomocysteinemia is an independent risk factor for early myocardial infarction, and is associated with a hypercoagulable state mediated by the extrinsic coagulation cascade.

Regulation of functions of vascular wall cells by tissue factor pathway inhibitor: basic and clinical aspects

Tissue factor pathway inhibitor (TFPI) is a Kunitz-type protease inhibitor that inhibits the initial reactions of blood coagulation. A major pool of TFPI is the form associated with the surface of endothelial cells, which is speculated to play an important role in regulating the functions of vascular wall cells. TFPI consists of 3 tandem Kunitz inhibitor domains, the first and second of which inhibit the tissue factor-factor VIIa complex and factor Xa, respectively. Recent findings indicate that TFPI has another function, ie, the modulation of cell proliferation. This function is based on the interaction of the C-terminal region of TFPI with these cells. In addition to endothelial cells, it has been shown that many other vascular wall cells can synthesize TFPI, eg, mesangial cells, smooth muscle cells, monocytes, fibroblasts, and cardiomyocytes. TFPI is associated with these cells mainly through heparan sulfate proteoglycans on their surface. However, recent findings suggest that there are several other candidates for TFPI-binding proteins on these cells. On the other hand, studies on plasma levels of TFPI in patients with various diseases suggest that TFPI may be a marker of endothelial cell dysfunction. An increasing number of reports suggest that recombinant TFPI may attenuate thrombosis and prevent restenosis. Clinical trials are needed to explore these possibilities. Recent reports also indicate that the application of recombinant TFPI or TFPI gene transfer prevents restenosis in addition to thrombosis after arterial injury in the animal model; corroboration of these reports awaits clinical investigation.