Prothrombin fragments F1+2, thrombin-antithrombin III complexes, fibrin monomers and fibrinogen in patients with coronary atherosclerosis

A System-Wide Investigation and Stratification of the Hemostatic Proteome in Premature Myocardial Infarction

Introduction

Advancing understanding of key factors that determine the magnitude of the hemostatic response may facilitate the identification of individuals at risk of generating an occlusive thrombus as a result of an atherothrombotic event such as an acute Myocardial Infarction (MI). While fibrinogen levels are a recognized risk factor for MI, the association of thrombotic risk with other coagulation proteins is inconsistent. This is likely due to the complex balance of pro- and anticoagulant factors in any individual.

Methods

We compared measured levels of pro- and anticoagulant proteins in plasma from 162 patients who suffered an MI at an early age (MI <50 y) and 186 age- and gender-matched healthy controls with no history of CAD. We then used the measurements from these individuals as inputs for an established mathematical model to investigate how small variations in hemostatic factors affect the overall amplitude of the hemostatic response and to identify differential key drivers of the hemostatic response in male and female patients and controls.

Results

Plasma from the MI patients contained significantly higher levels of Tissue Factor (P = 0.007), the components of the tenase (FIX and FVIII; P < 0.0001 for both) and the prothrombinase complexes (FX; P = 0.003), and lower levels of Tissue Factor Pathway Inhibitor (TFPI; P = 0.033) than controls. The mathematical model, which generates time-dependent predictions describing the depletion, activation, and interaction of the main procoagulant factors and inhibitors, identified different patterns of hemostatic response between MI patients and controls, and additionally, between males and females. Whereas, in males, TF, FVIII, FIX, and the inhibitor TFPI contribute to the differences seen between case and controls, and in females, FII, FVIII, and FIX had the greatest influence on the generation of thrombin. We additionally show that further donor stratification may be possible according to the predicted donor response to anticoagulant therapy.

Conclusions

We suggest that modeling could be of value in enhancing our prediction of risk of premature MI, recurrent risk, and therapeutic efficacy.

[The role of thrombin in the pathogenesis of atherosclerosis and its complications]

Thrombin is a key regulator of the homeostasis system. Also, it actively participates in progression of various systemic diseases, including atherosclerosis. There is a large amount of experimental and clinical data on the involvement of thrombin in the pathogenesis of ischemic heart disease (IHD). Thus, studying thrombin activity regulation is promising. Also, the question whether it is possible to use biomarkers of thrombin activity as predictors of cardiovascular complications in IHD patients is relevant. The present review focuses on major mechanisms of thrombin functioning, its role in development and progression of atherosclerosis, and available tests for evaluation of thrombin functional activity. Major clinical studies are discussed that evaluated the efficacy of thrombin inhibitors and protease-activated receptor antagonists.

Soluble fibrin causes an acquired platelet glycoprotein VI signaling defect: implications for coagulopathy

Essentials Collagen and thrombin when used simultaneously generate highly activated platelets. The effect of thrombin stimulation on subsequent glycoprotein VI (GPVI) function was observed. Soluble fibrin, but not protease activated receptor (PAR) activation, prevented GPVI activation. Circulating soluble fibrin in coagulopathic blood may cause an acquired GPVI signaling defect.

SUMMARY

Background In coagulopathic blood, circulating thrombin may drive platelet dysfunction. Methods/Results Using calcium dye-loaded platelets, the effect of thrombin exposure and soluble fibrin generation on subsequent platelet GPVI function was investigated. Exposure of apixaban-treated platelet-rich plasma (12% PRP) to thrombin (1-10 nm), but not ADP or thromboxane mimetic U46619 exposure, dramatically blocked subsequent GPVI activation by convulxin, collagen-related peptide or fibrillar collagen. Consistent with soluble fibrin multimerizing and binding GPVI, the onset of convulxin insensitivity required 200-500 s of thrombin exposure, was not mimicked by exposure to PAR-1/4 activating peptides, was not observed with washed platelets, and was blocked by fibrin polymerization inhibitor (GPRP) or factor XIIIa inhibitor (T101). PAR-1 signaling through Gαq was not required because vorapaxar blocked thrombin-induced calcium mobilization but had no effect on the ability of thrombin to impair GPVI-signaling. Convulxin insensitivity was unaffected by the metalloprotease inhibitor GM6001 or the αIIb β3 antagonist GR144053, indicating negligible roles for GPVI shedding or αIIb β3 binding of fibrin. Thrombin treatment of washed platelets resuspended in purified fibrinogen also produced convulxin insensitivity that was prevented by GPRP. Exposure of apixaban/PPACK-treated whole blood to thrombin-treated fibrinogen resulted in > 50% decrease in platelet deposition in a collagen microfluidic assay that required soluble fibrin assembly. Conclusions Conversion of only 1% plasma fibrinogen in coagulopathic blood would generate 90 nm soluble fibrin, far exceeding ~1 nmGPVI in blood. Soluble fibrin, rather than thrombin-induced platelet activation throuh PAR-1 and PAR-4, downregulated GPVI-signaling in response to stimuli, and may lead to subsequent hypofunction of endogenous or transfused platelets.

The Alzheimer's disease peptide β-amyloid promotes thrombin generation through activation of coagulation factor XII

Essentials How the Alzheimer's disease (AD) peptide β-amyloid (Aβ) disrupts neuronal function in the disease is unclear. Factor (F) XII initiates blood clotting via FXI, and thrombosis has been implicated in AD. Aβ triggers FXII-dependent FXI and thrombin activation, evidence of which is seen in AD plasma. Aβ-triggered clotting could contribute to neuronal dysfunction in AD and be a novel therapeutic target.

SUMMARY

Background β-Amyloid (Aβ) is a key pathologic element in Alzheimer's disease (AD), but the mechanisms by which it disrupts neuronal function in vivo are not completely understood. AD is characterized by a prothrombotic state, which could contribute to neuronal dysfunction by affecting cerebral blood flow and inducing inflammation. The plasma protein factor XII triggers clot formation via the intrinsic coagulation cascade, and has been implicated in thrombosis. Objectives To investigate the potential for Aβ to contribute to a prothrombotic state. Methods and results We show that Aβ activates FXII, resulting in FXI activation and thrombin generation in human plasma, thereby establishing Aβ as a possible driver of prothrombotic states. We provide evidence for this process in AD by demonstrating decreased levels of FXI and its inhibitor C1 esterase inhibitor in AD patient plasma, suggesting chronic activation, inhibition and clearance of FXI in AD. Activation of the intrinsic coagulation pathway in AD is further supported by elevated fibrin levels in AD patient plasma. Conclusions The ability of Aβ to promote coagulation via the FXII-driven contact system identifies new mechanisms by which it could contribute to neuronal dysfunction and suggests potential new therapeutic targets in AD.

Endogenous pro-thrombotic biomarkers from the arm and leg may not have the same value

Objective

Assessments of endogenous pro-thrombotic biomarkers are performed invariably on arm blood. However, the commonest site for thrombosis is in the leg. A leg blood sample may reflect local pro-thrombotic processes more accurately than systemic arm blood. The aim was to determine whether pro-thrombotic biomarkers from standard venous arm samples differed significantly from leg samples.

Method

Concurrent blood samples were taken from an ankle/lower calf varicose vein and an ante-cubital vein in 24 patients awaiting laser treatment as well as age approximated and sex matched healthy controls without venous disease. The following assays were performed: thrombin–antithrombin (ng/ml), antithrombin (%) activity, microparticles (nM), fibrinogen (mg/dl), prothrombin fragment 1.2 (F1.2) (pM) and P-selectin (ng/ml).

Results

Expressed as median (inter-quartile range). Significant arm/leg differences were observed in thrombin–antithrombin, antithrombin, prothrombin fragment 1.2 and P-selectin. The legs of patients had significantly reduced antithrombin activity and P-selectin concentrations compared to their arms (leg: 101 (90–108) versus arm: 112 (99–126), P = 0.001 and leg: 42 (26–52) versus 45 (27–52), P = 0.044, respectively). Control leg samples had significantly increased thrombin–antithrombin and P-selectin compared to control arm samples (leg: 2.1 (0.9–3.2) versus arm: 0.8 (0.5–1.7), P = 0.015 and leg: 36 (24–50) versus arm: 30 (23–41), P = 0.007, respectively). However, the control legs had significantly reduced F1.2 (leg: 265 (230–333) versus arm: 299 (236–361), P = 0.028). No significant arm/leg differences were detected in the microparticle or fibrinogen levels.

Conclusions

These findings indicate that venous arm blood is significantly different from venous leg blood in four out of six biomarkers studied. Recognition of local venous leg sampling as a site for investigation may unravel why the leg has a greater predisposition to thrombosis and lead the way towards an arm/leg differential test.

APC-PCI complex levels for screening of AAA in patients with peripheral atherosclerosis

To evaluate the use of activated protein C-protein C inhibitor (APC-PCI) complex levels for detection of abdominal aortic aneurysm (AAA) in patients with peripheral atherosclerotic disease (PAD). APC-PCI levels and aortic diameter evaluated in 511 PAD patients without previously known AAA followed-up concerning survival for 4.8(0.5) years. AAA was found in 13% of patients. Aortic diameter correlated (r = 0.138; p = 0.002) with APC-PCI levels which were higher (0.40[0.45] vs. 0.30[0.49] μg/l; p = 0.004) in patients with AAA. This difference persisted in multivariate analysis (p = 0.029). A threshold value of APC-PCI ≥0.15 μg/L showed a specificity of 11%, a sensitivity of 97% and a negative predictive value of 96% for an AAA diagnosis. APC-PCI levels were higher in patients with AAA, and showed high sensitivity but low specificity for the diagnosis and can therefore not be considered as a screening tool in PAD patients. An AAA prevalence of 13% in patients with PAD indicates a need for AAA screening within this population.

Individuals with coronary artery disease at a young age and features of the metabolic syndrome have an increased prothrombotic potential

The relation between coagulation and atherosclerosis has been extensively described, pointing towards a hypercoagulable state in patients with atherosclerosis, especially in young individuals. However, not all studies were conclusive. It is known that the metabolic syndrome (MetS), a risk factor for coronary artery disease (CAD), is related to a higher incidence of thrombo-embolic events. We hypothesised that individuals with CAD at a young age and MetS have an increased prothrombotic potential. It was the study objective to analyse the endogenous thrombin potential (ETP) and related thrombin generation parameters in patients with CAD before the age of 51 in men and 56 in women with and without MetS features and their healthy first-degree relatives. In this case-control study we included 118 CAD patients and 50 first-degree relatives (controls). Parameters of thrombin generation were obtained with calibrated automated thrombinography. An adjusted general linear model (GLM) showed a positive association between the peak thrombin levels and the presence of CAD at a young age. Based on the NCEP criteria we divided our patient group in CAD patients with and without MetS, and compared them to the controls without MetS. We showed that CAD patients with MetS have increased ETP levels, both in comparison with healthy first-degree relatives and with CAD patients without MetS. There were no differences in ETP between patients without MetS and healthy controls. In conclusion, this study shows that individuals with CAD at a young age and MetS features have an increased prothrombotic potential, compared to CAD patients without MetS.

Aorta structural alterations in term neonates: the role of birth and maternal characteristics

AIM

To evaluate the influence of selected maternal and neonatal characteristics on aorta walls in term, appropriately grown-for-gestational age newborns.

METHODS

Age, parity, previous abortions, weight, height, body mass index before and after delivery, smoking, and history of hypertension, of diabetes, of cardiovascular diseases, and of dyslipidemia were all assessed in seventy mothers. They delivered 34 males and 36 females healthy term newborns who underwent ultrasound evaluation of the anteroposterior infrarenal abdominal aorta diameter (APAO), biochemical profile (glucose, insulin, total cholesterol, HDL and LDL cholesterol, triglycerides, fibrinogen, and D-dimers homeostasis model assessment [HOMAIR]index), and biometric parameters.

RESULTS

APAO was related to newborn length (r = +0.36; P = 0.001), head circumference (r = +0.37; P = 0.001), gestational age (r = +0.40, P = 0.0005), HOMA index (r = +0.24; P = 0.04), and D-dimers (r = +0.33, P = 0.004). Smoke influenced APAO values (odds ratio: 1.80; confidence interval 95%: 1.05-3.30), as well as diabetes during pregnancy (r = +0.42, P = 0.0002). Maternal height influenced neonatal APAO (r = +0.47, P = 0.00003). Multiple regression analysis outlined neonatal D-dimers as still significantly related to neonatal APAO values.

CONCLUSIONS

Many maternal and neonatal characteristics could influence aorta structures. Neonatal D-dimers are independently related to APAO.

Aorta structural alterations in term neonates: the role of birth and maternal characteristics

Aim. To evaluate the influence of selected maternal and neonatal characteristics on aorta walls in term, appropriately grown-for-gestational age newborns. Methods. Age, parity, previous abortions, weight, height, body mass index before and after delivery, smoking, and history of hypertension, of diabetes, of cardiovascular diseases, and of dyslipidemia were all assessed in seventy mothers. They delivered 34 males and 36 females healthy term newborns who underwent ultrasound evaluation of the anteroposterior infrarenal abdominal aorta diameter (APAO), biochemical profile (glucose, insulin, total cholesterol, HDL and LDL cholesterol, triglycerides, fibrinogen, and D-dimers homeostasis model assessment [HOMA_IR]index), and biometric parameters. Results. APAO was related to newborn length (r = +0.36; P = 0.001), head circumference (r = +0.37; P = 0.001), gestational age (r = +0.40, P = 0.0005), HOMA index (r = +0.24; P = 0.04), and D-dimers (r = +0.33, P = 0.004). Smoke influenced APAO values (odds ratio: 1.80; confidence interval 95%: 1.05–3.30), as well as diabetes during pregnancy (r = +0.42, P = 0.0002). Maternal height influenced neonatal APAO (r = +0.47, P = 0.00003). Multiple regression analysis outlined neonatal D-dimers as still significantly related to neonatal APAO values. Conclusions. Many maternal and neonatal characteristics could influence aorta structures. Neonatal D-dimers are independently related to APAO.

Plasminogen and fibrinogen plasma levels in coronary artery disease

Objective

The formation of thrombi at the site of atherosclerotic lesions plays a central role in atherothrombosis. Impaired fibrinolysis may exacerbate pre-existing coronary artery disease and potentiate its evolution. While the fibrinogen plasma level has been strongly associated with the severity of coronary artery disease, its relevance in the evaluation of plasminogen in coronary artery disease patients remains unclear. This study evaluated fibrinogen and plasminogen levels in subjects with coronary artery disease as diagnosed by angiography.

Methods

This is a cross-sectional study. Blood samples obtained from 17 subjects with angiographically normal coronary arteries (controls), 12 with mild/moderate atheromatosis and 28 with severe atheromatosis were evaluated. Plasma plasminogen and fibrinogen levels were measured by chromogenic and coagulometric methods, respectively.

Results

Fibrinogen levels were significantly higher in the severe atheromatosis group compared to the other groups(p-value < 0.0001). A significant positive correlation was observed between the severity of coronary artery diseaseand increasing fibrinogen levels (r = 0.50; p-value < 0.0001) and between fibrinogen and plasminogen levels (r =0.46; p-value < 0.0001). There were no significant differences in the plasminogen levels between groups.

Conclusion

Plasma fibrinogen, but not plasminogen levels were higher in patients with coronary artery disease compared to angiographically normal subjects. The plasma fibrinogen levels also appear to be associated with the severity of the disease. The results of this study provide no evidence of a significant correlation between plasma plasminogen levels and the progress of coronary stenosis in the study population.

Prothrombin fragments in cardiovascular disease

Prothrombin fragment 1+2 (F1+2), which comes from in vivo cleavage of prothrombin by factor Xa, is considered to be useful for diagnosis of thrombosis. Recognition of the central role of thrombosis in the pathogenesis ofcardiovascular disease has prompted growing interest in the association o F1+2 with cardiovascular clinical syndromes. Increased F1+2 levels have reported in venous thromboembolism, inflammation, cancer, sepsis, acute coronary syndromes, stroke, peripheral arterial disease, atrial fibrillation and during the postoperative period. However, a clear relationship with the appearance of thrombosis has not always been consistently demonstrated. Besides its potential prognostic and diagnostic value, it could also be usefu in assessing the impact of various therapies. However, it should be kept in mind that measurement of hemostasis activation markers has several important biological and methodological disadvantages. Activation markers reflect the presence of thrombosis in any vascular bed, so they are not specific. Furthermore, elevations occur not only in the presence of overt thrombosis but also during the hypercoagulable state. The cutoff level to be used for the definition of elevations is still largely unknown due to the use of different analytical methods, none of which have been standardized until know. Finally, the prognostic value of F1+2 and other markers of coagulation activation remains to be fully defined in future studies.

Intima-media thickness of common carotid and brachial arteries and prothrombin fragment 1 + 2 are associated with left ventricular diastolic dysfunction in patients with myocardial infarction

AIMS

To investigate the association between intima-media thickness of brachial and common carotid arteries and factors of the coagulation- and fibrinolysis-system with left ventricular diastolic dysfunction in patients with a previous myocardial infarction.

PATIENTS AND METHODS

One hundred and twenty three patients, men (76%) and women (24%) aged between 32 and 81 years with a history of previous acute myocardial infarction were included. B-mode ultrasound of common carotid and brachial arteries and echocardiography with tissue Doppler imaging (TDI) were evaluated. Factors of the coagulation- and fibrinolysis-system were also measured.

RESULTS

In patients with previous myocardial infarction, late diastolic filling time was significantly and positively associated with log Prothrombin fragment 1 + 2 (P < 0.001) and with calculated intima-media area (cIMa) of the both common carotid and brachial arteries (P < 0.05). Mitral early-to-late flow velocity ratio (E/A) was significantly and negatively associated with log Prothrombin fragment 1 + 2 (P < 0.001), total cholesterol and cIMa of the both common carotid and brachial arteries (P < 0.05). Moreover both late diastolic filling time and mitral E/A correlated significantly with age and systolic blood pressure. In stepwise multiple regression analysis, log Prothrombin fragment 1 + 2 remained the only variable with independent significant correlation to late diastolic filling time and mitral E/A.

CONCLUSIONS

In a population sample of patients with myocardial infarction, late diastolic filling time and mitral E/A were associated with cIMa of common carotid and brachial arteries, systolic blood pressure, and prothrombin fragment 1 + 2, suggesting a relationship between diastolic dysfunction, thrombin generation and atherosclerosis.

Activated protein C-protein C inhibitor complex in peripheral arterial disease

BACKGROUND

Thrombin activation measured by the levels of the complex between activated protein C (APC) and the protein C inhibitor (PCI) is elevated in several atherosclerotic disorders. The aim of this study was to evaluate whether levels of the APC-PCI complex are related to the prognosis in peripheral arterial disease (PAD). Longitudinal study performed at the Vascular Centre, Malmö University Hospital, Sweden.

METHODS

APC-PCI complex levels were analyzed in 268 consecutive patients hospitalized for PAD and in 42 healthy controls (median age, 74 years). Patients (n = 35) with warfarin treatment less than 4 weeks before APC-PCI sampling were excluded from analysis. Data-based medical records of all 233 remaining patients (median age, 72 [64-79] years) were searched for vascular events such as hospitalization because of atherosclerotic disease, operative or endovascular recanalization of peripheral arteries, transtibial or transfemoral amputation because of PAD, acute coronary syndrome, stroke, or death.

RESULTS

Median duration of follow-up was 16 months (interquartile range, 12-23 months). APC-PCI complex levels were higher in PAD patients than in controls (0.240 [0.180-0.320] microg/L vs. 0.140 [0.190-0.220] microg/L; p < 0.0001) but not associated with an increased risk for death (p = 0.2054) or events during follow-up (p = 0.2850). Independent predictors of future events were low b-hemoglobin (p = 0.0084), high b-leukocytes (p = 0.0034), and history of a previous vascular event (p = 0.0032). Age (p = 0.0286), high p-creatinine (p = 0.0165), and history of a previous event (p = 0.0311) were independent predictors of death.

CONCLUSION

APC-PCI complex levels were higher in PAD patients than in controls, but did not predict the clinical outcome. The effect of a possible prethrombotic state, as reflected in increased APC-PCI levels, on prognosis and severity of atherosclerotic disease has to be further investigated.

Haemostatic and fibrinolytic factors in men with a small abdominal aortic aneurysm

BACKGROUND

: The presence of an abdominal aortic aneurysm (AAA) independently predicts cardiovascular disease (CVD) and its complications. Levels of plasma markers of fibrin turnover are raised in men with a large AAA (at least 5.5 cm) and predict CVD risk in healthy subjects. This study examined fibrin turnover in men with a small AAA.

METHODS

: Seventy-five men with a small AAA (30-55 mm) were compared with 90 controls matched for age, sex and race. Haemostatic and fibrinolytic parameters were assessed.

RESULTS

: Men with a small AAA had higher mean levels of fibrinogen (2.92 versus 2.59 g/l; P = 0.019), thrombin-antithrombin (TAT) complex (4.57 versus 1.89 ng/ml; P < 0.001), prothrombin F1 + 2 (1.13 versus 0.82 ng/ml; P = 0.004) and D-dimer (346.7 versus 120.2 ng/ml; P < 0.001). All markers correlated with maximum aortic diameter determined by ultrasonography. On multivariable regression the association between presence of an AAA and fibrinogen, TAT complex, prothrombin F1 + 2 and D-dimer levels remained significant after adjustment for confounding influences.

CONCLUSION

: Fibrin turnover was increased in these men with a small AAA, independently of concomitant CVD, conventional risk factors and inflammatory markers. Enhanced fibrin turnover may contribute to the risk of cardiac complications in this group.

Exercise training-induced changes in coagulation factors in older adults

The coagulation cascade plays a critical role in the development of cardiovascular disease (CVD). Elevated plasma prothrombin fragment 1 + 2 (F1 + 2) and factor VIII antigen (FVIII:Ag) levels have been associated with a hypercoagulable state, enhancing the risk for vascular thrombotic events. Aerobic training is known to reduce CVD risk, and an improved coagulation profile may contribute to this reduction.

PURPOSE

To analyze the effect of 6 months of standardized aerobic exercise training on resting F1 + 2 and FVIII:Ag levels in men and postmenopausal women aged 50-75 while accounting for several possibly confounding factors.

MATERIALS AND METHODS

Sedentary men (N=16) and women (N=31) underwent supervised aerobic training 3 d x wk(-1) for 6 months while maintaining the American Heart Association step 1 diet. Baseline and final testing included measurement of F1 + 2, FVIII:Ag, plasma lipoprotein-lipid levels, body composition, and VO2max.

RESULTS

When adjusted for baseline values and changes in diastolic blood pressure with training, F1 + 2 was found to decrease significantly with exercise training from 1.493 +/- 0.058 to 1.422 +/- 0.059 nM (P=0.014). FVIII:Ag levels were found to increase significantly with training when adjusted for baseline values, from 152.5 +/- 6.7% of standard at baseline to 156.0 +/- 6.1% of standard at final testing (P=0.005). Training-induced changes in coagulation markers were independent of changes in blood lipids, aerobic capacity, and body composition.

CONCLUSIONS

: These results indicate that endurance training has a significant impact on the coagulation cascade, reducing coagulation activity in the common pathway and thrombin formation at rest while increasing the activation potential of the intrinsic pathway.

Plasma markers of activated hemostasis in the early diagnosis of acute coronary syndromes

BACKGROUND

Because acute coronary syndromes (ACS) are caused by intracoronary thrombosis, plasma markers of coagulation have relevance for early diagnosis.

AIMS AND OBJECTIVES

To provide a critical review of these studies and specific attempts to close the diagnostic time gap left by traditional plasma markers of heart injury.

METHODS

Studies of ACS patients, with at least one control group, were included when blood samples were taken within 24 h after first symptoms prior to medication or intervention. Special attention was paid to studies reporting diagnostic performance, or combination of several markers into a single diagnostic index.

RESULTS

Markers with short plasma half-life (FPA, TAT, etc.) reflect ongoing thrombosis and may identify patients at increased risk. Markers with longer half-life (F1+2, D-Dimer, etc.) may be more useful to indicate a single acute thrombotic event. However, results are highly variable and depend on sampling time, clot property, degree of coronary obstruction and physiological condition. Early diagnostic performance of hemostatic markers was poor even when combined with heart injury markers.

CONCLUSIONS

Early measurement of hemostatic plasma markers in ACS patients provides pathophysiological information and may be helpful in risk stratification or to monitor anticoagulant therapy, but does not seem useful in routine clinical diagnosis of ACS.

Activated protein C-protein C inhibitor complex: A new biological marker for aortic aneurysms

OBJECTIVE

The concentration of the complex between activated protein C (APC) and protein C inhibitor (PCI) is a measure of thrombin generation. We studied whether it can provide information useful for the diagnosis and treatment of arterial vascular disease.

METHODS

Blood was obtained from 429 vascular patients admitted consecutively during September 2004 to March 2005. The APC-PCI complex was measured by using a sandwich immunofluorometric method. The patients were divided into cohorts according to the planned treatment and compared with a control group of healthy individuals.

RESULTS

The APC-PCI complex concentration varied from 0.08 to 2.50 microg/L. In the cohort of patients with aortic aneurysms (n = 78), the median APC-PCI value was 0.45 (10th to 90th percentile, 0.24-1.47), and values were clearly increased compared with all other cohorts (P < .0001). Patients with carotid disease (n = 73) yielded a median of 0.22 (10th to 90th percentile, 0.15-0.48). The median for claudicants (n = 74) was 0.26 microg/L (10th to 90th percentile, 0.15-0.75), which was higher than in those (n = 97) with critical ischemia (0.20; 10th to 90th percentile, 0.13-0.36; P < .0023). The cohort with other forms of atherosclerotic disease (n = 40) had a median of 0.23 (10th to 90th percentile, 0.14-0.42), whereas the value for a cohort of 21 patients with venous disease was 0.19 (10th to 90th percentile, 0.10-0.34). The median was 0.15 (10th to 90th percentile, 0.10-0.23) for the control group (n = 121).

CONCLUSIONS

Patients with atherosclerosis had an increased APC-PCI concentration that corresponded to increased generation of thrombin. Patients with aortic aneurysm had a threefold higher median concentration than the control group. We suggest that this remarkable increase is caused by the local activation of coagulation, and we surmise that APC-PCI measurements can be used as a screening tool to identify patients with aortic aneurysms.

Association between early postoperative coagulation activation and peri-operative myocardial ischaemia in patients undergoing vascular surgery

We investigated the association of peri-operative myocardial ischaemia with activation of coagulation and endogenous fibrinolysis in patients undergoing vascular surgery. In 50 patients, continuous Holter monitoring was performed to assess peri-operative myocardial ischaemia and 12-lead electrocardiography was recorded preoperatively and 72 h postoperatively to assess myocardial infarction. Serial blood samples were drawn peri-operatively to determine the concentrations of fibrin monomers (for activation of coagulation), D-dimer (for endogenous fibrinolysis) and cardiac troponin T and I. Patients with myocardial ischaemia showed higher concentrations of fibrin monomers at 48 h, and higher concentrations of d-dimer preoperatively and at 24 and 48 h postoperatively. In patients with peri-operative myocardial ischaemia, strong positive correlations were observed between fibrin monomer and D-dimer concentrations at 15 min and 4 h postoperatively, and cardiac troponins at 15 min and at 4, 24, 48 and 72 h postoperatively. Early postoperative activation of coagulation and fibrinolysis is associated with peri-operative myocardial cell damage among patients who are at risk for, or have a history of, coronary artery disease plus peri-operative myocardial ischaemia.

Increased thrombin generation and circulating levels of tumour necrosis factor-alpha in patients with chronic Helicobacter pylori-positive gastritis

BACKGROUND

Conflicting data have been reported concerning the relationship between Helicobacter pylori infection and coronary heart disease.

AIM

To evaluate clotting system activation and plasma levels of tumour necrosis factor-alpha, a procoagulant cytokine, in patients with H. pylori-positive and -negative gastritis.

METHODS

Three groups of patients were identified: 38 with H. pylori-positive gastritis, 18 with H. pylori-negative gastritis, and 40 H. pylori-negative controls with normal gastric mucosa. Plasma levels of prothrombin fragment 1 + 2 (F1 + 2) and tumour necrosis factor-alpha were assayed. Patients were also controlled after 2 and 6 months following standard H. pylori eradication treatment.

RESULTS

At baseline, fragment 1 + 2 and tumour necrosis factor-alpha levels in H. pylori-positive patients were significantly higher than those in H. pylori-negative patients with gastritis (P < 0.05 and P < 0.01, respectively). After H. pylori eradication, fragment 1 + 2 and tumour necrosis factor-alpha levels showed a significant decrease at 2 months (P = 0.03 and P = 0.02, respectively) and a further reduction at 6 months, reaching levels observed in H. pylori-negative patients and controls.

CONCLUSIONS

The increase thrombin generation rate and the correlation of plasma fragment 1 + 2 and tumour necrosis factor-alpha levels in H. pylori-positive patients suggest a role for inflammation in mediating the relationship between H. pylori infection and activation of the clotting system.

Prothrombin Fragment 1+2 Is Associated With Carotid Intima-Media Thickness in Subjects Free of Clinical Cardiovascular Disease

Background and Purpose— Thrombin, a central enzyme in the clotting cascade, plays a role not only in thrombosis but also in the progression of atherosclerosis. We studied the relationship between prothrombin fragment 1+2 (F1+2), a specific marker of thrombin generation in vivo, and carotid intima-media thickness (IMT), an index of subclinical atherosclerosis.

Methods— We examined 181 asymptomatic middle-aged subjects (mean age 55.6 years, 76.7% men) free of overt clinical atherosclerotic disease. F1+2 was measured by enzyme-linked immunosorbent assay and IMT by duplex ultrasonography of carotid artery. Multiple linear regression analysis was used to assess the relationship between the 2 parameters.

Results— Compared with individuals in the lowest tertile of F1+2, those in the upper tertile (>0.55 nmol/L) showed significantly higher IMT ( P <0.01). In correlation analysis, a positive relationship was found between plasma F1+2 and carotid IMT. F1+2 also correlated positively with cholesterol ( P <0.008) and low-density lipoprotein cholesterol ( P <0.005), but not with blood pressure or body mass index. In the multivariate analysis, the association of F1+2 with carotid IMT remained significant ( P <0.001) after adjustment for age, sex, body mass index, systolic blood pressure, cholesterol, diabetes, and smoking.

Conclusions— In a population sample of adults without clinically overt atherosclerotic disease, the plasma levels of F1+2 were significantly associated with carotid IMT, suggesting a relationship between thrombin generation and the development atherosclerosis.

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.

Exercise-induced changes in coagulation and fibrinolysis in healthy populations and patients with cardiovascular disease

This review highlights the clinical significance of coagulation and fibrinolytic responses, and adaptations in healthy individuals and patients with cardiovascular disease (CVD). Much of the review focuses on indicators of the potential for coagulation and fibrinolysis. The terms 'coagulation potential' and 'fibrinolytic potential' are used frequently, as much of the literature in the area of exercise haemostasis evaluates factors that reflect an increased potential for coagulation, while coagulation per se, may or may not be occurring. Similarly, fibrinolysis is definitively the lysis of inappropriate or excessive blood clot, which may or may not be occurring when the enzymes that stimulate fibrinolysis are activated. Nevertheless, markers of coagulation and fibrinolytic potential are associated with CVD, ischaemic events, and cardiovascular mortality. Additionally, fibrinolytic potential is associated with other established CVD risk factors. Ischaemic events triggered by physical exertion are more likely to occur due to an occlusive thrombus, suggesting the exercise-induced responses related to haemostasis are of clinical significance. The magnitude of increase in coagulation potential, platelet aggregation and fibrinolysis appears to be primarily determined by exercise intensity. Patients with CVD may also have a larger increase in coagulation potential during acute exercise than healthy individuals. Additionally, the magnitude of the fibrinolytic response is largely related to the resting fibrinolytic profile of the individual. In particular, high resting plasminogen activator inhibitor-1 may diminish the magnitude of tissue plasminogen activator response during acute exercise. Therefore, acute responses to exercise may increase the risk of ischaemic event. However, chronic aerobic exercise training may decrease coagulation potential and increase fibrinolytic potential in both healthy individuals and CVD patients. Due to the aforementioned importance of resting fibrinolysis on the fibrinolytic response to exercise, chronic aerobic exercise training may cause favourable adaptations that could contribute to decreased risk for ischaemic event, both at rest and during physical exertion.

Predictive Value of Inflammatory and Hemostatic Parameters, Atherosclerotic Risk Factors, and Chest X-Ray for Aortic Arch Atheromatosis

BACKGROUND AND PURPOSE

Aortic arch atheromatosis (AAA) is a common cause of cerebral embolism. Transesophageal echocardiography (TEE) shows not only the extension of atherosclerotic plaques but also the mobility of superimposed thrombi. In most cases AAA is only detected after the embolic event. This study was therefore designed to identify predictive factors for AAA.

METHODS

One hundred seven consecutive patients referred for routine TEE were included in the study. Patients on warfarin therapy, with a history of recent surgery, or with any signs of infectious, immunological, or malignant diseases were excluded.

RESULTS

Diabetes mellitus carried the highest risk for AAA (odds ratio, 3.0), followed by hyperlipidemia (2.5) and arterial hypertension (2.3). Age >70 years was accompanied with a 1.8-fold increased risk. Patients with aortic calcifications on standard chest x-ray had a 4.6-fold higher prevalence. Severe AAA was associated with higher levels of C-reactive protein (14.6+/-14.1 versus 4.9+/-7.2 mg/L), fibrinogen (4.20+/-1.22 versus 3.45+/-1.29 mg/L), plasmin/antiplasmin complexes (728+/-297 versus 453+/-243 microg/L), and D-dimers (980+/-652 versus 444+/-349 microg/L).

CONCLUSIONS

AAA is accompanied by elevation of inflammatory and hemostatic parameters. Patients with classic cardiovascular risk factors and aortic calcifications on chest x-ray have a higher prevalence. Further prospective studies are now warranted to establish a risk score to identify patients in whom TEE screening should be undertaken.

Leptin increase is associated with markers of the hemostatic system in obese healthy women

BACKGROUND

Leptin, a hormone secreted by the adipose tissue, might be a link between obesity and increased morbidity for cardiovascular disease. Leptin exerts proinflammatory, pro-angiogenic actions by activating a specific receptor (Ob-Rb) which is expressed in human endothelial cells. Thus, a link may exist between leptin expression and endothelial dysfunction.

OBJECTIVES

We sought to determine whether in obese women there is a correlation between leptin levels, endothelial perturbation and coagulative activation.

METHODS

Circulating levels of leptin, von Willebrand Factor (VWF), factor (F)VIIa, prothrombin fragment 1 + 2 (F1+2), were measured in 51 non-diabetic, obese women and in 51 normal-weight subjects, using immunoenzymatic assays.

RESULTS

Obese women had significantly higher levels of leptin, VWF, FVIIa, F1+2 compared with healthy women. Simple correlation coefficients showed significant correlation between leptin and either VWF, FVIIa, or F1+2 concentrations. A multiple linear regression analysis, performed to quantify further the relationship between leptin levels and the above-mentioned variables as well as the inflammatory marker C-reactive protein (CRP) and including age, body mass index (BMI), waist-hip ratio (WHR) and lipid parameters as potential confounders, revealed that only FVIIa and VWF were independently related to leptin levels. Reduction in adipose tissue after weight loss resulted in a decrease in both circulating leptin and endothelial and coagulative activation markers.

CONCLUSIONS

We suggest that leptin might have pro-atherogenic effects in vivo, with a mechanism involving endothelial cell activation.

Influence of two non-ionic radiographic contrast media with different osmolalities on coagulation in invasive cardiology. A prospective, randomised comparative study

PURPOSE

To investigate the influence of two non-ionic radiographic contrast media with different osmolality on thrombocytic function and the plasmatic coagulation system.

MATERIAL AND METHODS

The study was carried out as a randomised, prospective, comparative study with two contrast media in a heart catheter laboratory.

RESULTS

Activating influences on platelet aggregation, procoagulatory or profibrinolytic functions or injury to the endothelium could be ruled out. Apparently, also differences in substance properties, such as the media's ionic character or osmolality had no demonstrable influence on the interaction with haemostatis and blood vessels. An adjuvant, antithrombotic therapy was carried out, which consisted of platelet aggregation inhibitors and heparins.

CONCLUSION

Our findings agree with the results of recent clinical trials, which demonstrated no relevant disadvantage of non-ionic contrast media as regards thrombotic complications.

Factor XIII A-subunit concentration predicts outcome in stroke subjects and vascular outcome in healthy, middle-aged men

There is growing evidence for a role of factor XIII (FXIII) in vascular disease. FXIII measures were determined in (i) a nested case-control study from the Second Northwick Park Heart Study of 63 men with myocardial infarction (MI) and 124 age-matched controls and (ii) in a case-control study of 475 subjects with acute stroke and 461 controls followed up for 54 months for mortality. In both studies, measures of FXIII A- and B-subunit antigen, FXIII activity and prothrombin fragments (F1 + 2) were made. An in vitro model was used to investigate the effects of thrombin activity on FXIII A- and B-subunit antigen levels. In study 1, patients clinically free of coronary artery disease who later developed MI had lower adjusted FXIII A-subunit levels at recruitment (129.2%vs 113.3%, P = 0.007). In study 2, stroke patients with large vessel disease had lower A-subunit antigen levels (102.1%vs 127.2%, P < 0.001), but higher F1 + 2 levels (0.941%vs 0.753%, P < 0.05), than subjects with small vessel disease. Levels of FXIII A-subunit (100%vs 117%, P < 0.0001) were lower and F1 + 2 higher (1.020%vs 0.702%, P < 0.0001) in stroke patients who had died compared with those still alive at the end of the follow-up period. Low concentrations of FXIII A-subunit antigen predicted vascular outcome in otherwise healthy subjects and relate to both size of infarct and poor post-stroke survival in patients with acute ischaemic stroke. Low in vitro concentrations of FXIII A-subunit antigen wererelated to increased thrombin generation and, thus, increased risk of thrombotic events.

Elevated levels of Factor XI are associated with cardiovascular disease in women

Coronary artery disease (CAD) continues to be the most frequent cause of death among women in the United States. Although elevated levels of clotting factors have been associated with CAD, few of these studies have been performed in women. Elevated levels of Factor XI have previously been associated with venous thrombosis, but little is known about its effect on arterial thrombosis. We selected women referred for cardiac catheterization who were found to have either normal coronaries or evidence of severe CAD and compared levels of homocysteine, anticardiolipin IgG/IgM antibodies, fibrinogen, platelet count, Factor VII, Factor VIII and Factor XI. Women with severe CAD had significantly higher levels of Factor XI than those without CAD (128% vs. 82%, p<0.04). Statistical adjustment for age, diabetes, hypertension, total cholesterol (TC), current smoking, or BMI had no effect on the independent association between CAD status and Factor XI. Factor XI was higher in women with total cholesterol levels >6.18 mmol/l (>239 mg/dl) compared with normocholesteremic women and was also higher in the upper tertile of age, but even when adjusted for these, the association remained significant. This initial study suggests that Factor XI may be an important parameter in arterial as well as venous thrombosis.

Intravenous magnesium does not influence the activity of the coagulation cascade

Experimental arterial thrombus formation is reduced during intravenous magnesium infusion. It is well documented that magnesium reduces platelet reactivity, but the antithrombotic effect could also originate from anticoagulant properties or increased fibrinolysis. We therefore evaluated the effect of intravenous magnesium on prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III complex (TAT) concentrations, and fibrin degradation products (FbDP) in a randomized, cross-over study in 14 healthy volunteers. Citrated blood samples were collected at 0, 30, and 180 min. An additional in vitro study on magnesium's effect on the activity of different coagulation factors was carried out. A transient increase was seen in F1 + 2 and TAT after 30 min but without any significant difference between the placebo and magnesium period. FbDP did not change significantly between the two treatments. Increasing concentrations of magnesium dose-dependently decreased binding of activated factor X to activated factor VII (FVIIa), but the decrease was slight and probably without any significance for coagulation at the concentrations tested. No effect was observed on the activity of FVIIa or activated factor VIII. In conclusion, no significant differences were observed on markers of coagulation or fibrinolytic activity during intravenous magnesium infusion. These results indicate that the observed antithrombotic effect of magnesium is more likely to arise from the previously observed platelet inhibition.

Hemostatic markers in patients at risk of cerebral ischemia

BACKGROUND

Increased levels of markers of hemostasis may assist in the determination of the extent of carotid occlusive disease and the identification of neurologically intact individuals at increased risk of ischemic events.

METHODS

We conducted a prospective study of 304 subjects, including 82 with a recent (< or =7 days) transient ischemic attack (TIA), 157 asymptomatic individuals with a cervical bruit, and 65 control subjects. Baseline evaluation included a neurological assessment, ECG, cervical ultrasonography, and cerebral CT and/or MRI. Levels of markers of coagulation and fibrinolytic activity were also determined. Results were analyzed in relation to the degree of carotid disease and the subsequent occurrence of cerebral and cardiac ischemic events.

RESULTS

Over a mean follow-up period of 2.8 years (SD, 1.3 years), 114 ischemic events occurred. Survival analyses showed that prothrombin fragment 1.2 (F(1.2)) was a predictor of time to cerebral and cardiac ischemic events in the combined TIA and asymptomatic bruit group (relative risk [RR], 1.46; 95% CI, 1.18 to 1.81) as well as in the asymptomatic bruit group separately (RR, 1.70; 95% CI, 1.14 to 2.53). In the TIA group, both F(1.2) (RR, 2.36; 95% CI, 1.19 to 4.68) and severe (> or =80%) carotid stenosis (RR, 3.53; 95% CI, 1.19 to 10.51) were predictive of time to ischemic stroke, myocardial infarction, or vascular death.

CONCLUSIONS

In patients with TIAs and in asymptomatic individuals with cervical bruits, F(1.2) levels were found to be independent predictors of subsequent cerebral and cardiac ischemic events. Our results are consistent with an active role of the coagulation system through upregulation of thrombin in carotid disease progression and in the pathogenesis of ischemic events in patients at risk.