Fibrin formation and degradation in patients with arteriosclerotic disease

The Use of Clot Strength as a Predictor of Thrombosis in Peripheral Artery Disease

BACKGROUND

Graft/stent thrombosis is the leading cause of amputation in patients over 60, and while dual antiplatelet therapy is the standard of care, there is a significant variability in platelet response and limited guidance on measuring effectiveness. Thromboelastography with platelet mapping (TEG-PM) can objectively detail an individual's coagulation profile, namely the strength of the clot and its response to antiplatelet medication. Although TEG-PM has been used for predicting postoperative bleeding and assessing platelet dysfunction in traumatic brain injury, its application in thrombosis diseases such as peripheral artery disease remains unexplored. The aim of this observational study was to determine if objective measures of clot strength could predict a high clinical risk of thrombosis.

METHODS

Patients >60 years with peripheral artery disease undergoing revascularization were prospectively evaluated from 2021 to 2023. They were clinically followed for 1 year to detect any thrombotic events. TEG-PM was used to objectively evaluate coagulation profiles in patients at 1, 3, 6, and 9 months. These follow-up periods were chosen based on studies showing that 1-3 month intervals in the first year after lower extremity revascularization optimize therapy and risk control. The TEG-PM data preceding a thrombotic/stenotic event in patients with thrombosis was compared to the last known well TEG-PM event in those without a thrombotic/stenotic event. We stratified the groups based on the occurrence of thrombosis/stenotic events. Descriptive statistics were applied to characterize each group and a chi-square test was conducted to assess the variance between both groups. An unpaired t-test was run to identify differences in platelet function. Receiver operating characteristic analysis was performed to determine the optimal TEG-PM cutoff for predicting a higher risk of thrombosis.

RESULTS

One hundred and fifty-eight patients were analyzed, from whom 28 (17.7%) experienced a thrombotic event. The thrombosis cohort exhibited significantly greater MAADP, MAFibrin, and MAThrombin [50.2 vs. 40.0, P < 0.05], [18.19 vs. 14.64, P < 0.05], and [63.8 vs. 58.5, P < 0.05], respectively, indicative of greater clot strength. By receiver operating characteristic analysis, the optimal predictor cut-off for MAADP, indicating a higher risk of thrombosis, was >42 mm [P < 0.05] with 82% sensitivity and 50% specificity.

CONCLUSIONS

An increase in clot strength was found to be predictive of thrombosis/stenosis within 30 days. Using a MAADP cut-off greater than 42 mm might serve as an alternative approach to tailor the use of antiplatelet medication, potentially reducing the risk of thrombosis.

Thrombin as target for prevention of recurrent events after acute coronary syndromes

The mechanism underlying thrombus formation in acute coronary syndrome (ACS) involves both platelets and thrombin. While both pathways are targeted in acute care, platelet inhibition has been predominantly administered in the chronic phase, yet thrombin plays a key role in platelet activation and fibrin formation. Among ACS patients, there is also a persistent chronic increase in thrombin generation, which is associated with a higher rate of adverse events. In the setting of post-ACS care with rivaroxaban or vorapaxar, targeting thrombin has been associated with decreased thrombin generation and reduced cardiovascular events, but has been associated with increased bleeding risk. We explored the evidence supporting thrombin generation in the pathophysiology of recurrent events post-ACS and the role of thrombin as a viable therapeutic target. One specific target is factor XI inhibition, which is involved in thrombin generation, but may also allow for the preservation of normal hemostasis.

Relationship between serum homocysteine, fibrinogen, lipoprotein-a level, and peripheral arterial disease: a dose-response meta-analysis

AIM

At present, the relationship between serum homocysteine (Hcy), fibrinogen (FIB), lipoprotein-a (LPa), and PAD is uncertain, and there has been no meta-analysis to establish the dose-response relationship between their exposure levels and PAD.

METHODS AND RESULTS

Relevant literature published in PubMed, Embase, and Web of Science was retrieved. The robust error meta-regression method was used to assess the linear and non-linear dose-response relationship between exposure level and PAD risk. A total of 68 articles, involving 565,209 participants, were included. Combined with continuous variables, the serum Hcy, FIB, and LPa levels of PAD patients were significantly higher than those of healthy individuals. The odds ratios (ORs) of PAD for individuals with high Hcy, FIB, and LPa levels compared with those with low levels were 1.47, 1.14, and 1.76, respectively. The study also showed that circulating Hcy, FIB, and LPa were significantly elevated in patients with PAD compared with controls. The level of Hcy and the risk of PAD presented a U-shaped distribution. The nonlinear dose-response model showed that each 1 μmol/L increase in serum Hcy increased the risk of PAD by 7%. Similarly, for each 10 mg/dL FIB and 10 mg/dL LPa increases, the risk of PAD increased by 3% and 6%, respectively.

CONCLUSIONS

This meta-analysis provided evidence that elevated Hcy, PIB, and LPa levels may increase the risk of PAD, and the risk of PAD increases with the increase in serum exposure within a certain range. By controlling Hcy level, the incidence of PAD may be reduced to control the PAD growing epidemic.

TRIAL REGISTRATION NUMBER

PROSPERO (CRD42021250501), https://www.crd.york.ac.uk/prospero/.

Epidemiology of Peripheral Artery Disease and Polyvascular Disease

Atherosclerotic lower extremity peripheral artery disease (PAD) is increasingly recognized as an important cause of cardiovascular morbidity and mortality that affects >230 million people worldwide. Traditional cardiovascular risk factors, including advanced age, smoking, and diabetes, are strongly linked to an increase risk of PAD. Although PAD has been historically underappreciated compared with coronary artery disease and stroke, greater attention on PAD in recent years has led to important new epidemiological insights in the areas of thrombosis, inflammation, dyslipidemia, and microvascular disease. In addition, the concept of polyvascular disease, or clinically evident atherosclerosis in multiple arterial beds, is increasingly identified as a particularly malignant cardiovascular disease worthy of special clinical attention and further study. It is noteworthy that PAD may increase the risk of adverse outcomes in similar or even greater magnitude than coronary disease or stroke. In this review, we highlight important new advances in the epidemiology of PAD with a particular focus on polyvascular disease, emerging biomarkers, and differential risk pathways for PAD compared with other atherosclerotic diseases.

The effect of exercise on coagulation and fibrinolysis factors in patients with peripheral arterial disease

Peripheral arterial disease is a widely prevalent atherosclerotic occlusive disorder. Symptoms commence with exercise-induced pain in the lower extremities, known as claudication. Despite the fact that exercise has been shown to improve fibrinolytic profile some patients, the effect of exercise on coagulation and fibrinolysis cascades in claudicants has not been comprehensively defined. Literature search in English language yielded 13 studies of exercise on claudicants, including 420 patients. Claudicants tend to have a higher coagulation activity at rest compared to healthy individuals, a trend that persists even after exercise. Post-exercise coagulation activity of claudicants is increased when compared to their respective baseline levels, but it is so in a non-consistent manner. From the available data, it has been suggested that claudicants have a functional and effective fibrinolytic mechanism in place, operating continuously at a relatively higher activity level compared to healthy individuals. Fibrinolysis seems to be activated by exercise; a positive outcome with a prolonged effect as shown by a few of the studies. A final conclusion whether coagulation or fibrinolysis activity is affected mostly by exercise type and intensity in claudicants could not be answered. All conclusions regarding the effect of exercise on the coagulation and fibrinolysis mechanisms should be taken under cautious consideration, due to the limited number of studies, the small number of patients and the different exercise strategies employed in each study. Further randomized studies with similar exercise protocols could provide safer conclusions in the future.

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.

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.

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.

The effects of aspirin and nonselective beta blockade on the acute prothrombotic response to psychosocial stress in apparently healthy subjects

We hypothesized that the 2 cardiovascular drugs aspirin and propranolol attenuate the prothrombotic response to acute psychosocial stress relative to placebo medication. We randomized 56 healthy subjects, double-blind, to 5-day treatment with an oral dose of either 100 mg of aspirin plus 80 mg of propranolol combined, single aspirin, single propranolol, or placebo medication. Thereafter, subjects underwent a 13-minute psychosocial stressor. Plasma levels of von Willebrand factor antigen (VWF:Ag), fibrinogen, coagulation factor VII (FVII:C) and XII (FXII:C) activity, and D-dimer were determined in blood samples collected immediately pre- and post-stress and 45 minutes post-stress. The stress-induced changes in prothrombotic measures were adjusted for gender, age, body mass index, mean arterial blood pressure, smoking status, and sleep quality. There was an increase in VWF:Ag levels from immediately pre-stress to 45 minutes post-stress in the placebo group relative to the 3 subject groups with verum medication (P's </= 0.019; relative increase in VWF:Ag between 17% and 21%); however, the VWF:Ag response to stress was not significantly different between the three groups with verum medication. The stress responses in fibrinogen, FVII:C, FXII:C, and D-dimer were similar in all 4 medication groups. The combination of aspirin with propranolol, single aspirin, and single propranolol all attenuated the acute response in plasma VWF:Ag levels to psychosocial stress. This suggests that these cardiovascular drugs might exert limited protection from the development of stress-triggered coronary thrombosis.

Aspirin, but not propranolol, attenuates the acute stress-induced increase in circulating levels of interleukin-6: a randomized, double-blind, placebo-controlled study

Psychosocial stress might increase the risk of atherothrombotic events by setting off an elevation in circulating levels of the proinflammatory cytokine interleukin (IL)-6. We investigated the effect of aspirin and propranolol on the responsiveness of plasma IL-6 levels to acute psychosocial stress. For 5 days, 64 healthy subjects were randomized, double-blind, to daily oral aspirin 100mg plus long-acting propranolol 80 mg, aspirin 100mg plus placebo, long-acting propranolol 80 mg plus placebo, or placebo plus placebo. Thereafter, all subjects underwent the 13-min Trier Social Stress Test, which combines a preparation phase, a job interview, and a mental arithmetic task. Plasma IL-6 levels were measured in blood samples collected immediately pre- and post-stress, and 45 min and 105 min thereafter. The change in IL-6 from pre-stress to 105 min post-stress differed between subjects with aspirin medication and those without (p =0.033; eta p2=0.059). IL-6 levels increased less from pre-stress to 105 min post-stress (p <0.027) and were lower (p =0.010) at 105 min post-stress in subjects with aspirin than in subjects without aspirin. The significance of these results was maintained when controlling for gender, age, waist-to-hip ratio, mean arterial blood pressure, and smoking status. Medication with propranolol was not significantly associated with the stress-induced change in IL-6 levels. Also, aspirin and propranolol did not significantly interact in determining the IL-6 stress response. Aspirin but not propranolol attenuated the stress-induced increase in plasma IL-6 levels. This suggests one mechanism by which aspirin treatment might reduce the risk of atherothrombotic events triggered by acute mental stress.

Diet and haemostatic processes

Diet plays an important role in the primary and secondary prevention of cardiovascular disease. The growing perception that abnormal haemostatic processes of coagulation, platelet aggregation and fibrinolysis contribute to cardiovascular disease aetiology motivated this review on the relationships of diet, specific foods and nutrients with haemostatic function. Functional endpoints that reflect the function and status of some of these processes and which can be measured in dietary trials are identified. The effects of energy intake and expenditure, alcohol, total fat and specific fatty acids, non-starch polysaccharides (dietary fibre), antioxidant nutrients and some foods on a variety of haemostatic markers are reviewed. The results indicate that the prudent low-fat, high-fibre diet and maintenance of ideal body weight recommended to protect against and treat hyperlipidaemia and coronary heart disease will also benefit haemostatic profiles. It is concluded that more research on specific effects is needed for improved recommendations on a population level for prevention of cardiovascular disease.

Mild peripheral neuropathy prevents both leg muscular ischaemia and activation of exercise-induced coagulation in Type 2 diabetic patients with peripheral artery disease

AIM

To study the influence of peripheral neuropathy on intermittent claudication in patients with Type 2 diabetes (T2DM).

METHODS

Twenty-five patients with T2DM were grouped according to the ankle/brachial index (ABI): 10 with ABI > 0.9 without peripheral artery disease (PAD; group T2DM) and 15 with ABI < 0.9 with PAD (group T2DM + PAD). Twelve individuals without T2DM with PAD (group PAD without T2DM) were also enrolled. Tests for peripheral neuropathy were performed in all patients. ABI, rate pressure product, prothrombin fragments 1 + 2 (F1+2), thrombin-anti-thrombin complex (TAT), and d-dimer were measured before and after a treadmill test. During exercise both initial and absolute claudication distance and electrocardiogram readings were recorded.

RESULTS

We found mild peripheral neuropathy in 20% of group T2DM and 46.7% of group T2DM + PAD (P < 0.01). After exercise, the rate pressure product increased in each group; ABI fell in T2DM + PAD (P < 0.0001) and in PAD without T2DM (P = 0.0005); the fall was greater in the latter group. Initial and absolute claudication distances were similar in PAD patients. In group T2DM + PAD, absolute claudication distance was longer in the subgroup without peripheral neuropathy (P < 0.05), whereas ABI and rate pressure products were similar. F1+2 values at rest were higher in group T2DM + PAD. After exercise, F1+2 values and TAT increased only in group PAD without T2DM.

CONCLUSION

Only group PAD without T2DM experienced muscular ischaemia, whereas group T2DM + PAD did not. Mild peripheral neuropathy may have prevented them from reaching the point of muscular ischaemia during the treadmill test, because they stopped exercising with the early onset of pain. Reaching a false absolute claudication distance may induce ischaemic preconditioning. These findings suggest a possible protective role of mild peripheral neuropathy in T2DM patients with intermittent claudication, by preventing further activation of coagulation during treadmill testing.

The role of fibrinogen and fibrinolysis in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with high rates of cerebrovascular and cardiovascular events; PAD is a marker of systemic atherosclerosis. As a result, standard therapy for all PAD patients should be directed at both peripheral and systemic atherosclerosis. Modification of established risk factors in the form of smoking cessation, correcting hypertension, optimizing diabetic control and normalizing lipids is essential. Furthermore, novel risk factors have emerged including fibrinogen and other hemostatic factors. Fibrinogen is a coagulation factor and a marker of the acute phase response (inflammation), a platelet activator, a major determinant of plasma viscosity and a component of the atherosclerotic plaque. Fibrinogen appears not only to predict the severity of PAD, but also serves as a marker for future development of PAD. Whether reducing the levels of fibrinogen and other coagulation factors will decrease the incidence and progression of PAD remains to be resolved. This review summarizes the role of fibrinogen in the pathogenesis of PAD and its association with other hemostatic factors. The role of fibrinolysis in patients with PAD is also considered.

D-dimer identifies stages in the progression of diabetes mellitus from family history of diabetes to cardiovascular complications

AIM

The aim of the study was to ascertain whether there is variation in the fibrinolytic/coagulation component of diabetes associated with disease progression to macrovascular complications and whether D-dimer can discriminate such variation.

METHODS

A total of 343 participants were selected based on clinical status and divided into 7 groups: control, family history of diabetes, pre-diabetes with/without CVD, diabetes with/without CVD and CVD only. Plasma D-dimer was tested. Statistical analysis was performed on log normalised data by ANOVA, Fisher's LSD post hoc test. After the initial analysis, data were classified and re-analysed by quartiles, interquartile range and 95(th) percentile.

RESULTS

An overall significant difference between groups (p<0.002) and a steady rise in D-dimer levels that became increasingly higher than control as the disease progressed from pre-diabetes to cardiovascular complications was observed. A statistically significant difference was observed between control versus diabetes (p<0.0005). Analysis of data by quartiles and percentiles gave qualitatively similar results, but a greater significant difference between control versus pre-diabetes at 3rd quartile and interquartile range (p<0.014).

CONCLUSION

We report changes in D-dimer levels that may indicate diabetes disease progression to macrovascular complications. Using D-dimer in conjunction with other biomarkers to identify stages of disease progression, commencing from pre-diabetes and continuing to development of asymptomatic and clinical cardiovascular disease in diabetes mellitus, is worthy of consideration.

Fibrin D-dimer fragments enhance inflammatory responses in macrophages: role in advancing atherosclerosis

1. Fibrin D-dimer is considered a consistent and independent marker of the risk of cardiovascular disease in population studies, as well as being related to atherosclerosis severity in patients. However, the role of fibrin D-dimer in macrophage-derived foam cell formation during atherogenesis remains unclear. 2. In the present study, using microarray techniques, we determined the effects of 100 ng/mL fibrin D-dimer fragments on macrophage cell function in atherosclerosis by investigating the expression levels of 128 genes related to the atherosclerotic pathophysiological processes. 3. The results showed that 27 genes were enhanced by D-dimer fragments to over twofold of control. These 27 genes belonged to six groups and included adhesion molecules, extracellular molecules, molecules related to lipid transport and metabolism, cell growth and proliferation molecules, transcription regulators and genes responsive to stress. We proceeded to determine the expression levels of five of these genes (intercellular adhesion molecule-1, matrix metalloproteinase-9, oxidized low-density lipoprotein receptor 1, vascular endothelial growth factor A and peroxisome proliferator-activated receptor alpha) using SYBR real-time polymerase chain reaction. The results confirmed gene upregulation, similar to the results obtained with the microarray, following treatment with D-dimer. 4. Therefore, the present study provides direct evidence regarding the pro-atherosclerotic role of D-dimer in macrophage function, which is mainly to enhance the inflammatory response during macrophage-derived foam cell formation.

D-dimer local expression is increased in symptomatic patients undergoing carotid endarterectomy

BACKGROUND

Although atherosclerosis is a silent widespread disease, the focal character of the lesions triggering the clinical manifestations is unquestionable. We hypothesized that symptomatic patients with advanced, unstable carotid plaques have increased local intraplaque and circulating levels of fibrin-fibrinogen related products.

METHODS

Plaque tissue and plasma samples were studied in 106 patients undergoing endarterectomy for symptomatic and asymptomatic carotid disease. Fibrin-fibrinogen related products were evaluated by ELISA, Western-blotting, and histology. All tested parameters were compared with patient carotid symptomatology, multiple vascular risk factors (VRF), bilateral carotid pathology, ultrasound examination, and previous therapies with statins and/or antiplatelet drugs.

RESULTS

In symptomatic patients, plasma D-dimer was elevated in patients with unstable carotid plaques (UNS) compared with stable (STA) ones (857+/-121 vs. 692+/-156 ng/ml, p=0. 026). Furthermore, plasma D-dimer was significantly increased in patients with a coexistence of carotid and coronary artery disease, compared to others (976+/-325 vs. 714+/-197 ng/ml; p<0.001). Intra-plaque D-dimer content was increased in ulcerated-complicated (UC) plaques compared with fibrous non-complicated (F) plaques in symptomatic patients (5.9+/-1 vs. 1.8+/-1, p<0.001), and in patients with hypercholesterolaemia, compared with those with normal cholesterol levels (6.1+/-1 vs. 2.9+/-0.7; p=0.027). However, there was no correlation between D-dimer content in the carotid plaque and plasma D-dimer levels.

CONCLUSIONS

Hypercholesterolemia and UC plaques appear to be associated with high fibrin intraplaque turnover as demonstrated by higher intraplaque D-dimer. Plasma markers of fibrin turnover were increased in UNS plaques, and in patients with coexisting carotid and coronary artery disease. Although, both plasma and plaque D-dimers were associated with unstable carotid disease, the usefulness of the measurement of plasma D-dimer in these patients should be confirmed by prospective studies.

Haemostasis, inflammation and renal function following exercise in patients with intermittent claudication on statin and aspirin therapy

Background

Previous studies have suggested that exercise in patients with intermittent claudication (IC) may induce a systemic thrombo-inflammatory response. The effect of secondary prevention therapy on this response is unknown. This study aimed to investigate the effects of treadmill exercise on markers of coagulation activation, inflammation and renal function in patients with IC, receiving aspirin and statin therapy compared to healthy controls.

Methods

Samples were taken before, immediately and 1 hour after exercising on a treadmill in 20 patients with IC and 20 healthy volunteers. Interleukin-6 (IL-6), thrombin-anti-thrombin complex (TAT) and fibrin D-dimer were measured by ELISA. High sensitivity CRP (HsCRP) and urinary albumin were measured via a nephelometric technique, urinary protein via a turbidometric assay and N-acetyl-β-D-glucosaminidase (NAG) via a colorimetric assay.

Results

Elevated baseline levels of Hs-CRP, IL-6, white cell counts, D-dimer and urinary NAG occurred in patients with IC compared to volunteers (p > 0.05). Following exercise there was no increase in Hs CRP or IL-6. D-dimer levels significantly increased following exercise in the patients and volunteers. TAT levels increased immediately after exercise in the patient group only and were significantly increased at 1 hour in both patients and volunteers. A transient rise in the protein creatinine ratio occurred in both groups (p < 0.007), and in albumin creatinine ratio in the patient group. There was no change in urinary NAG.

Conclusion

Elevated markers of inflammation occurred in patients with IC on statin and aspirin therapy but these did not increase following exercise. However, acute exercise resulted in a prothrombotic state evident in both groups, although this was more prolonged in patient with IC. The clinical significance of these findings in patients who are known to be at an increased risk of cardiac and other thrombotic event are unclear.

Activated coagulation during open and endovascular abdominal aortic aneurysm repair

OBJECTIVE

The study was conducted to determine activation of coagulation in patients undergoing open and endovascular infrarenal abdominal aortic aneurysm repair (EVAR).

METHODS

In a prospective, comparative study, 30 consecutive patients undergoing open repair (n = 15) or EVAR (n = 15) were investigated. Blood samples to determine fibrinopeptide A, fibrin monomer, thrombin-antithrombin complex, and D-dimer were taken up to 5 days postoperatively. Routine hematologic and hematochemical parameters as well as clinical data were collected.

RESULTS

Both groups showed comparable demographic variables. Operating time was longer in open repair (249 +/- 77 minutes vs 186 +/- 69 minutes, P < .05). Perioperatively elevated markers of coagulation were measured in both groups. Fibrinopeptide A levels did not differ significantly between the groups (P = .55). The levels of fibrin monomer and thrombin-antithrombin complex were significantly higher in patients undergoing EVAR (P < .0001), reflecting increased thrombin activity and thrombin formation compared with open surgery. The D-dimer level did not differ significantly between the groups. These results were also valid after correction for hemodilution.

CONCLUSION

These data suggest increased procoagulant activity in EVAR compared with open surgery. A procoagulant state may favor possible morbidity derived from micro- and macrovascular thrombosis, such as in myocardial infarction, multiple organ dysfunction, venous thrombosis and thromboembolism, or disseminated intravascular coagulation.

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.

Relation between platelet microaggregates and ankle brachial index in patients with peripheral arterial disease

INTRODUCTION

Peripheral arterial disease is one of the systemic atherosclerotic diseases, and patients with the disorder are classified in the high risk group of coronary artery disease. A lower ankle brachial index is a frequent finding in peripheral arterial disease. While platelet microaggregates are a significant predictor of adverse clinical outcome in coronary artery disease, the significance of platelet aggregability in peripheral arterial disease has not been elucidated.

MATERIALS AND METHODS

Small platelet aggregates measured using laser-light scattering and ankle brachial index were determined in 42 patients with both coronary artery disease and peripheral arterial disease (peripheral group), 56 patients with only coronary artery disease (coronary group) and 32 patients without both (control group).

RESULTS

The level of small platelet aggregates was increased significantly in the peripheral group (4.3 x 10(4) [range 2.2 x 10(4) to 7.4 x 10(4)]) compared with both the coronary (1.1 x 10(4) [range 0.3 x 10(4) to 5.0 x 10(4)]) and control groups (0.5 x 10(4) [range 0.1 x 10(4) to 0.9 x 10(4)]). There was a significant inverse correlation between log small platelet aggregates and ankle brachial index (n=130, r=-0.422, p<0.001). Multivariate logistic regression analysis revealed that a lower ankle brachial index (<0.90) was an independent determinant of increased levels of small platelet aggregates.

CONCLUSIONS

Platelet aggregability was increased in patients with peripheral arterial disease with the degree of platelet aggregation being closely associated with ankle brachial index. It is possible that this change in platelet activity may be one mechanism to explain why a lower ankle brachial index is a predictor of poor prognosis in patients with peripheral arterial disease.

Clopidogrel has no effect on D-dimer and thrombin-antithrombin III levels in patients with peripheral arterial disease undergoing peripheral percutaneous transluminal angioplasty

OBJECTIVE

Coagulation activation markers are significantly elevated in patients with peripheral arterial disease compared with healthy controls. The more severe the disease, the higher the markers. Increased coagulation activation may contribute to the disease process and the risk of complications in patients with peripheral arterial disease, particularly after endovascular intervention. Animal studies have shown that clopidogrel significantly inhibits coagulation activation. The aim of this study was to determine whether combination of aspirin and clopidogrel affects thrombin-antithrombin III and D-dimer in patients with intermittent claudication undergoing angioplasty, compared with aspirin alone.

METHODS

This was a double blind, randomized placebo-controlled trial conducted in a vascular unit in a tertiary referral center. One hundred thirty-two patients with intermittent claudication were randomized to clopidogrel and aspirin or placebo and aspirin, with a loading dose 12 hours before endovascular intervention. D-dimer and thrombin-antithrombin III (TAT) levels were measured using enzyme-linked immunosorbent assay at baseline, 1 hour before, and 1 hour, 24 hours, and 30 days after intervention in 103 patients who underwent endovascular intervention.

RESULTS

There was a significant rise in D-dimer levels at 1 hour and 24 hours after angioplasty in both groups (placebo group: 63.69, 141.45, 122.18 ng/mL; clopidogrel group: 103.79, 159.95, 134.69 ng/mL), but no difference between the two groups (P = .514). Similarly there was a significant rise in TAT levels at 1 hour after angioplasty in both groups (placebo group: 2.93, 6.16 microg/L; clopidogrel group: 3.39, 5.27 microg/L), with no significant difference between the two groups (P = .746).

CONCLUSION

Endovascular intervention results in a significant increase in TAT and D-dimer. The addition of clopidogrel to aspirin has no effect on TAT and D-dimer before or after endovascular intervention.

Markers of coagulation activation, endothelial stimulation and inflammation in patients with peripheral arterial disease

OBJECTIVES

Patients with peripheral arterial disease have a significantly increased risk of cardiovascular and cerebrovascular mortality. Studies have shown that some haemostatic and inflammatory markers are elevated in these patients but the effect of the severity of the disease has not been fully documented. The aim of this study was to assess the level of coagulation activation, endothelial stimulation and inflammation in patients with claudication and critical limb ischaemia (CLI) compared to healthy controls.

DESIGN AND METHODS

A prospective observational study was conducted amongst 202 subjects: 132 claudicants, 30 patients with critical ischaemia, and 40 controls. D-dimer (DD) and thrombin-antithrombin III (TAT) levels measured using ELISA as markers of coagulation activation. von Willebrand factor (vWF) and high-sensitivity C-reactive protein (CRP) levels were measured as markers of endothelial and inflammatory stimulation.

RESULTS

vWF and CRP levels were significantly higher in patients with intermittent claudication (1.9 U/ml, range 0.78-4.05; p < 0.001; 3.4 mg/l, range 0.15-24; p > 0.001, respectively) and critical ischaemia (2.36 U/ml; range 1.03-5.69; p < 0.001; 7.17 mg/ml, range 0.15-174; p < 0.001, respectively) compared to controls (1.28 U/ml, range 0.62-3.13; 1.04, range 0.15-7.59 mg/l). DD was also significantly higher in claudicants (48.6 microg/ml; range 2-1741; p < 0.001) and in patients with CLI (61.1 microg/ml, range 3.65-1963; p < 0.001) compared to controls (26.1 microg/ml, range 9.65-203.1). TAT levels were significantly higher in CLI (3.14 mg/l, range 2.09-58.11), compared to controls (2.36 mg/l, range 1.49-7.38; p = 0.004). Patients with CLI had significantly higher levels of CRP, vWF, and TAT than claudicants.

CONCLUSIONS

Coagulation activation and endothelial stimulation are significantly increased in patients with peripheral arterial disease compared to healthy controls. Coagulation and endothelial activation increases with the severity of the arterial disease.

Do Haemostasis Activation Markers that Predict Cardiovascular Disease Exist?

Recognition of the central role of thrombosis in the pathogenesis of cardiovascular disease has prompted growing interest in the association of haemostatic variables with cardiovascular disease. In investigating the predictive value of haemostasis markers, a promising type of measurement is that of the activation products of coagulation and fibrinolysis: prothrombin fragment 1+2 (F1+2), fibrinopeptide A (FPA), soluble fibrin,thrombin-antithrombin (TAT), plasmin-antiplasmin(PAP) complexes and D-dimer. D-dimer was most extensively studied and there is substantial evidence that D-dimer is a strong, consistent predictor of cardiovascular events in the general population and inpatients with cardiovascular disease. Data on other markers are considerably less abundant and more controversial. The prognostic value of these markers remains to be fully defined in future epidemiological and clinical studies.

Blood coagulation and the risk of atherothrombosis: a complex relationship

The principles of Virchov's triad appear to be operational in atherothrombosis or arterial thrombosis: local flow changes and particularly vacular wall damage are the main pathophysiological elements. Furthermore, alterations in arterial blood composition are also involved although the specific role and importance of blood coagulation is an ongoing matter of debate. In this review we provide support for the hypothesis that activated blood coagulation is an essential determinant of the risk of atherothrombotic complications. We distinguish two phases in atherosclerosis: In the first phase, atherosclerosis develops under influence of "classical" risk factors, i.e. both genetic and acquired forces. While fibrinogen/fibrin molecules participate in early plaque lesions, increased activity of systemic coagulation is of no major influence on the risk of arterial thrombosis, except in rare cases where a number of specific procoagulant forces collide. Despite the presence of tissue factor – factor VII complex it is unlikely that all fibrin in the atherosclerotic plaque is the direct result from local clotting activity. The dominant effect of coagulation in this phase is anticoagulant, i.e. thrombin enhances protein C activation through its binding to endothelial thrombomodulin.

The second phase is characterized by advancing atherosclerosis, with greater impact of inflammation as indicated by an elevated level of plasma C-reactive protein, the result of increased production influenced by interleukin-6. Inflammation overwhelms protective anticoagulant forces, which in itself may have become less efficient due to down regulation of thrombomodulin and endothelial cell protein C receptor (EPCR) expression. In this phase, the inflammatory drive leads to recurrent induction of tissue factor and assembly of catalytic complexes on aggregated cells and on microparticles, maintaining a certain level of thrombin production and fibrin formation. In advanced atherosclerosis systemic and vascular wall driven coagulation becomes more important and elevated levels of D-dimer fragments should be interpreted as markers of this hypercoagulability.

The factor II G20210A gene polymorphism, but not factor V Arg506Gln, is associated with peripheral arterial disease: results of a case-control study

BACKGROUND

The FIIG20210A polymorphism has been associated with arterial wall thickness and atherothrombotic diseases in selected subgroups. The FVArg506Gln polymorphism does not seem to be associated with arterial diseases. Few data are available on these polymorphisms and the risk of peripheral arterial disease (PAD).

OBJECTIVES

To study the association between the FIIG20210A and FVArg506Gln polymorphisms and PAD and its clinical severity. To examine the potential interactions with traditional vascular risk factors.

PATIENTS AND METHODS

We studied 184 consecutive male patients under 70 years of age with symptomatic PAD and 330 age-matched male controls free of symptomatic PAD and with no cardiovascular history. We evaluated the FIIG20210A and FVArg506Gln polymorphisms in all subjects.

RESULTS

Mean age was 57.1 +/- 7.2 years (cases) and 56.7 +/- 7.6 years (controls). The FII20210A allele was more frequent in PAD patients with odds ratios (OR) of 3.77 (1.39-10.2) in univariate analysis and 4.30 (1.3-14.7) after adjustment for diabetes, smoking, hypertension and hypercholesterolemia. In smokers or past smokers the magnitude of the association was markedly increased but there was no evidence of an interaction between tobacco exposure and FIIG20210A. In case subjects, the FII20210A allele was also associated with critical ischemia [OR = 4.1 (1.1-15.7), P = 0.039 in multivariate analysis]. FVArg506Gln was not associated with PAD [OR = 0.65 (0.27-1.54) and 0.77 (0.28-2.1) in univariate and multivariate analyses, respectively].

CONCLUSIONS

The FIIG20210A gene polymorphism may be a risk factor for PAD and its severity. In contrast, the FVArg506Gln polymorphism is not associated with PAD.

Off-Pump coronary artery bypass operation does not increase procoagulant and fibrinolytic activity: preliminary results

BACKGROUND

This study analyzes the effects on coagulation and fibrinolysis comparing off-pump coronary artery bypass (OPCAB) and on-pump CABG operations.

METHODS

In a prospective, nonrandomized, comparative evaluation, patients scheduled for elective myocardial revascularization were studied. Due to possible confounding factors patients with postoperative retransfusion of mediastinal shed blood were excluded. Nine patients underwent OPCAB operation and 16 underwent on-pump CABG. Activated clotting time (ACT) was adjusted to 250 seconds in OPCAB (81 +/- 18 [mean +/- SD] IU/kg heparin) and to more than 480 seconds in on-pump CABG (400 IU/kg heparin, additional 10,000 IU in pump prime). Perioperatively blood samples were collected and hematologic and hemostatic variables including fibrinopeptide A (FPA), fibrin monomer (FM), thrombin-antithrombin complex (TAT), and D-dimer were analyzed.

RESULTS

Both groups showed comparable demographic variables. Number of grafts per patient was slightly higher in the on-pump group (3.6 +/- 0.6 versus 3.0 +/- 1.1, p = 0.23). The FPA levels did not differ significantly between the groups. The FM, TAT, and D-dimer values were significantly higher in on-pump CABG (p < 0.0001, p < 0.01, and p < 0.0001, respectively), reflecting increased coagulant and fibrinolytic activity. This was also the case when values were corrected for hemodilution.

CONCLUSIONS

Despite lower systemic anticoagulation activation of coagulation and fibrinolysis is reduced in OPCAB compared with on-pump CABG. Reduced thrombin generation and reduced fibrinolytic activity in OPCAB indicates better preservation of hemostasis. We suggest the term "preserved hemostasis" instead of "hypercoagulant activity" with respect to OPCAB.

Exercise in claudicants is accompanied by excessive thrombin generation

BACKGROUND

exercise in IC leads to ischaemia-reperfusion injury of leg muscles and a systemic inflammatory response, but the effect of on coagulation is unknown.

OBJECTIVE

to compare the effect of exercise on thrombin formation and fibrin turnover in patients with IC (n = 10), and age and sex matched smokers ([S] n = 5) and non-smokers ([NS] n = 5) without peripheral vascular disease.

METHODS

blood was taken from subjects 60 and 30 min before, and 1, 5, 20, 40, 60 and 120 min after, treadmill exercise. Markers of thrombin generation (thrombin-antithrombin complexes [TAT] and prothrombin fragments 1 + 2 [PF1 + 2]) and fibrin turnover (D-dimer and fibrin degradation products [FbDP]) were assayed at each time point.

RESULTS

following exercise, thrombin generation was significantly greater in the claudicant group compared to the control groups (Area Under Curve [AUC] post exercise IC vs S vs NS; TAT 3960 vs 1623 vs 1476 vs = 0.007 Kruskal-Wallis [KW]; PF1 + 2 163 vs 107 vs 123 p = 0.024 KW). Pre and post-exercise, fibrin turnover in claudicants was similar to smoking controls, but higher than non-smoking controls. (AUC post exercise IC vs NS; D-dimer 6340 vs 2754 p = 0.055 Mann-Whitney U[MW]; FbDP 45113 vs 21511 p = 0.009 MW).

CONCLUSION

when compared to non-claudicants, exercise in IC is associated with excessive production of thrombin. Despite this, claudicants have a similar level of fibrin turnover suggesting a possible defect in fibrinolysis. This prothrombotic state may contribute to the excess thrombotic morbidity and mortality suffered by claudicants.

Relation of levels of hemostatic factors and inflammatory markers to the ankle brachial index

Associations between hemostatic and inflammatory markers relative to the ankle brachial index (ABI), an indicator of the presence and severity of peripheral arterial disease (PAD), are not fully understood. We studied relations among selected hemostatic factors, inflammatory markers, and the ankle brachial index (ABI) in patients with and without peripheral arterial disease (PAD). Participants were 370 men and women with ABI <0.90 and 231 patients with ABI 0.90 to 1.50 identified from noninvasive vascular laboratories and general medicine practice. Blood factors were D-dimer, prothrombin 1.2, tissue plasminogen activator (t-PA) antigen, plasminogen activator inhibitor-1 (PAI-1), and inflammatory markers (high-sensitivity C-reactive protein [CRP], fibrinogen, and serum amyloid A [SAA]). Among patients without a history of cardiac or cerebrovascular disease, the ABI was significantly inversely associated with log D-dimer (p <0.001), log prothrombin 1.2 (p = 0.001), log CRP (p <0.001), and log fibrinogen (p = 0.005) in unadjusted analyses. In multivariable regression analyses adjusting for all blood factors as well as potential confounders, D-dimer was associated independently with ABI in participants with a history of cardiac or cerebrovascular disease (p = 0.003) and in participants without a history of cardiac or cerebrovascular disease (p = 0.017). In these analyses, CRP was associated independently with ABI among participants with a history of cardiac or cerebrovascular disease (p = 0.026). CRP was not associated independently with ABI in participants without a history of cardiac or cerebrovascular disease. We conclude that D-dimer levels may be more sensitive than other blood markers for measuring the extent of atherosclerosis in lower extremity arteries.

Aprotinin in coronary operation with cardiopulmonary bypass: does "low-dose" aprotinin inhibit the inflammatory response?

BACKGROUND

Cardiopulmonary bypass induces a systemic inflammatory response. Aprotinin, a nonspecific proteinase inhibitor is known to improve postoperative hemostasis and may modify the inflammatory reaction. This study evaluates the effects of low-dose aprotinin on inflammatory markers in patients scheduled for elective coronary artery bypass grafting.

METHODS

Patients were prospectively randomized into two groups: the control group (C) (n = 14) and the low-dose aprotinin group (A) (n = 15) with (2 x 10(6) KIU = 280 mg) aprotinin added to the pump prime. Cytokine response (interleukin-6, soluble TNF II receptor), terminal complement production (SC5b-9), and neutrophil activation (lactoferrin) were assessed up to 6 hours postoperatively. Clinical data and hemostatic factors including fibrinopeptide A, thrombin-antithrombin complex, D-dimer, and plasmin/alpha2-antiplasmin were investigated.

RESULTS

In both study groups, a significant increase of all inflammatory markers was seen (IL-6, sTNF-IIR, SC5b-9, lactoferrin), p less than 0.001. Peak levels of complement production occurred after protamine administration, whereas cytokine increases were more pronounced postoperatively with marked elevation up to 6 hours. The markers did not differ significantly between groups throughout the study period (p > 0.05 at each time of determination). However, after protamine administration reduced fibrinolysis (D-dimer, plasmin/alpha2-antiplasmin) was detected in group A. Measurements for coagulation (fibrinopeptide A, thrombin-antithrombin complex) were not significantly influenced by aprotinin. The total amount of blood loss during the first 24 hours was significantly reduced in group A (p < 0.02).

CONCLUSIONS

Low-dose aprotinin added to the pump prime does not inhibit the inflammatory response caused by cardiopulmonary bypass, but improves postoperative hemostasis. A potential effect of high-dose aprotinin on inflammatory markers remains to be elucidated.

Associations between homocysteine and coagulation factors--a cross-sectional study in two populations of central Europe

Plasma homocysteine has been associated with vascular disease and mortality. Experimental studies and studies on patients with vascular disease have indicated a thrombogenic potential of raised homocysteine levels. Studies on community samples are rare. We investigated the associations between homocysteine levels and selected coagulation factors in population-based random samples of 187 men from Pardubice (Czech Republic) and 147 men from Augsburg (Germany), aged 45 to 64 years. Czech men had higher mean levels of plasma homocysteine (10.3 vs. 8.9 micromol/l, P<.001) and of fibrinogen, von Willebrand factor (vWF), prothrombin fragment 1+2 (F 1+2) and D-Dimer (each P<.05). Plasma homocysteine was positively correlated with fibrinogen (r=.34) and vWF (r=.23, each P<.001) only in Czechs, and with D-Dimer in both Czechs and Germans (r=.26 and.21, respectively). Formal testing for interaction regarding the intercountry differences in the relationship with homocysteine revealed significance only for fibrinogen (P<.01). In multivariate analyses, the association of homocysteine with D-Dimer remained statistically significant after adjustment for indicators of chronic inflammation and fibrinogen. No significant correlation was found with Factor VII (F VII) activity or F 1+2. Homocysteine levels were also unrelated to traditional risk factors. In conclusion, in these cross-sectional studies we found moderate to strong associations between homocysteine and components of the endogenous hemostatic and fibrinolytic systems. The associations were slightly different between Czech and German men. These findings may help to better understand the role of homocysteine in atherothrombotic diseases.

Activation of thrombosis and fibrinolysis following brain infarction

To clarify the sequence of alterations in the thrombotic and fibrinolytic systems after acute brain infarction, we prospectively examined sequential changes in coagulatory markers in 38 patients suffering from cardioembolic infarcts (CEI), 41 patients with atherothrombotic infarcts (ATI), 58 patients with lacunar infarcts (LI), and 32 age-matched controls. The plasma level of thrombin-antithrombin III complex (TAT), fibrinopeptide A (FpA), D-dimer, fibrin degradation products-E (FDP-E), fibrinogen, alpha2-plasmin inhibitor-plasmin complex (PIC), and percent activity of antithrombin III (AT-III) were measured within 48 h, at 1 week, and at 3 weeks after the stroke onset. Significantly elevated levels of TAT and FpA, which are both markers of thrombin formation, were observed in CEI patients, and these elevated levels were associated with increasing D-dimer levels for 3 weeks (P<0.0001). D-Dimer in CEI patients was significantly elevated compared to control, LI and ATI levels within 48 h (P<0.001). Percent activity of AT-III was significantly decreased in CEI patients for 3 weeks compared to this activity in controls, LI and ATI (P<0.001). TAT and FpA also increased significantly within 48 h in ATI subjects and declined thereafter. A significant elevation of FDP-E (P<0.001) and D-dimer (P<0.05, P<0.01) was detected in parallel with increasing fibrinogen for 3 weeks. However, there was no significant depletion of percent activity of AT-III in ATI. In LI subjects, no significant elevation of TAT, D-dimer or FDP-E were observed within 1 week. PIC increased significantly in three subtypes of brain infarcts, but did not differ significantly among the three subtypes for 3 weeks. An accurate assessment of sequential alterations in thrombotic and fibrinolytic markers in the acute stage of brain infarct should contribute to the clinical diagnosis of brain infarct subtype. Alterations in these markers in response to activation of the coagulatory system are attributable to the different pathogenesis of ischemic stroke.

Hemostasis and fibrinolysis in patients with intermittent claudication: effects of prostaglandin E1

There is evidence that the coagulation system is activated in patients with peripheral arterial occlusive disease (PAOD). The beneficial effects of the vasoactive drug prostaglandin E1 (PGE1) may rely in part on the modulation of the coagulation system. The study was designed to evaluate the effects of PGE1 on hemostatic and fibrinolytic variables in patients with intermittent claudication. Therefore molecular markers of thrombin (prothrombin fragment 1+2, PTF 1+2; thrombin-antithrombin III complexes, TAT) and fibrin formation (fibrinopeptide A, FPA) and markers of the fibrinolytic activity (fibrin degradation products, D-dimers) were determined before and immediately after the first PGE1 dose (60 microg in 100 ml NaCl over 2 h i.v.) as well as after 4 weeks of daily infusion therapy in 12 PAOD patients and in eight control patients before and after a single placebo infusion. Plasma levels of PTF1+2, TAT, FPA and D-dimers tended to decrease after the initial dose of PGE1. Infusion therapy with PGE1 for 4 weeks led to a decrease of all hemostatic and fibrinolytic parameters with most pronounced changes for PFT1+2, D-dimers and plasminogen activator inhibitor-1 decreasing by 11% (P<0.05), 20% (P<0.05), and 7% (P<0.05), respectively. These variables remained unchanged in controls with placebo infusion. In summary, infusion therapy with PGE1 in patients with PAOD reduces thrombin formation and results in a decrease of fibrin degradation. PGE1 may thus reduce fibrin deposition involved in the pathogenesis of atherosclerosis.

Association of atherosclerosis with low back pain and the degree of disc degeneration

STUDY DESIGN

This was a cross-sectional observational study in which the abdominal aorta was evaluated for atheromatous lesions visible in computed tomographic scans in patients with and without low back pain.

OBJECTIVES

To evaluate whether patients with low back pain have more atherosclerosis in the abdominal aorta than patients without low back pain and whether the severity of atherosclerosis in the abdominal aorta correlates with the grade of disc damage.

SUMMARY OF BACKGROUND DATA

There are studies in which results indicate that insufficient blood supply may be a significant causative factor in disc degeneration. There are also studies in which smoking, one of the risk factors for arterial disease, has been correlated with low back pain. Calf pain has also been shown to correlate with low back pain. Results in a long-term follow-up study have further indicated an association between disc diseases and fatal ischemic heart disease. However, there seems to be only one postmortem study in which results show an association between atherosclerosis in the arteries of the lumbar area and disc diseases.

METHODS

Computed tomographic images of 29 patients with low back pain, who had been evaluated with computed tomographic discography for diagnostic purposes, were evaluated for the quantity of atherosclerotic calcifications visible on computed tomographic scans of the abdominal aorta. A similar evaluation was performed in an age- and sex-matched control group of 52 patients without low back pain selected from among the patients referred for abdominal computed tomography.

RESULTS

Sixteen (55%) of the 29 patients with low back pain had atherosclerotic calcifications visible on computed tomographic scans, whereas 11 (21%) of the 52 age-matched patients without low back pain were found to have aortic calcifications. Eleven (48%) patients with low back pain who were 50 years of age or less (n = 23) had aortic calcifications, whereas only 3 (8%) of the 36 control patients aged less than 50 years had aortic calcifications. There was no correlation between the amount of calcifications and the degree of disc degeneration assessed by computed tomographic discography.

CONCLUSIONS

A significant association is indicated between atheromatous lesions in the abdominal aorta and low back pain.

Tetranectin levels in patients with acute myocardial infarction and their alterations during thrombolytic treatment

Tetranectin (TN), a new regulator of fibrinolysis, was studied in the plasma of 60 patients with acute myocardial infarction (AMI) and 30 healthy subjects (HS), in relation to D-dimer (DD) and alpha 2-plasmin inhibitor (alpha 2-PI), to investigate its possible involvement in the pathophysiology of AMI. Thirty patients underwent thrombolytic treatment with fibrin-specific plasminogen activator (rt-PA) (group A); the other 30 patients, according to the exclusion criteria, were conventionally treated (group B). Twenty of the thrombolysized patients established early recanalization (subgroup A1), while 10 failed to respond to thrombolytic treatment (subgroup A2). Median (interquartile range), baseline plasma TN levels were lower in AMI patients compared to HS [8.27 (2.75) mg/L versus 12.1 (0.55) mg/L, P < 10(-6)]. In subgroup A1, TN increased at the end of rt-PA infusion and returned to the baseline levels 12 h later. A positive association between DD and TN release (3 h level minus baseline level) was found (rs = 0.48, P = 0.03) in subgroup A1. No significant alterations of TN levels were observed during therapy in subgroup A2 and group B. TN, DD and alpha 2-PI concentrations in group B remained relatively constant during the study period. This study provides evidence of a significant decrease of TN levels in AMI patients compared to healthy subjects and of a remarkable difference in the evolution of TN levels during thrombolytic treatment with rt-PA between recanalized and non-recanalized AMI patients. Thus, an involvement of TN in the formation and dissolution of fibrin clot in AMI patients is worthy of further investigation.

Activation of coagulation and fibrinolysis after rehabilitative exercise in patients with coronary artery disease

It has been suggested that blood coagulation be activated and fibrinolytic activity be impaired in patients with coronary artery disease (CAD). With regard to the activation of coagulation and fibrinolysis occurring during exercise in healthy individuals, we examined the hypothesis that rehabilitative exercise in patients with CAD might give rise to an exaggerated activation of coagulation. In 12 patients with angiographically documented CAD without myocardial infarction within the preceding 6 months (male, age 55+/-9 years [SD]) and in 12 healthy controls (male, 52+/-7 years), molecular markers of thrombin, fibrin, and plasmin formation were determined before and after a rehabilitative group exercise session lasting 1 hour. Resting levels of prothrombin fragment 1+2 were lower in patients with CAD (0.67+/-0.2 [SE] vs 1.04+/-0.2 nmol/L, p <0.001) and remained unchanged after exercise, whereas a significant increase was noted in controls (p <0.01). After exercise, plasma levels of thrombin-antithrombin III complexes and of fibrinopeptide A increased significantly in both groups, although there were more pronounced changes in controls. Exercise resulted in a marked generation of plasmin as indicated by plasmin-alpha2-antiplasmin complexes increasing 2.5-fold in patients (p <0.001) and threefold in controls (p <0.001). Repeated experiments in control subjects after administration of aspirin (day 1: 500 mg; days 2 to 5: 100 mg) documented that differences between groups could not be attributed to aspirin medication (100 mg/day) in patients with CAD. We concluded that rehabilitative exercise in patients with CAD beyond the immediate postinfarction period has no detrimental effects on thrombin, fibrin, and plasmin formation.

Reactivation of the coagulation system: rationale for long-term antithrombotic treatment

Coronary artery thrombosis superimposed on a disrupted atherosclerotic plaque has emerged as the pivotal pathophysiologic event in acute coronary syndromes (i.e., unstable angina, myocardial infarction, and sudden death). The various clinical manifestations depend on the extent and duration of thrombus deposition, which are determined by several local and systemic thrombogenic risk factors. The thrombotic response to plaque disruption involves both platelet activation and thrombin generation. Accordingly, combined treatment with aspirin and heparin has proved more efficacious than either treatment alone in the risk reduction of serious cardiac events in patients with unstable angina or non-Q-wave infarction. However, withdrawal of heparin is, even after prolonged treatment, associated with an increased short-term risk of serious cardiac events relative to the risk in patients given only aspirin. Furthermore, the long-term relative event rate seems not to be influenced by administration of heparin or direct antithrombins in the acute phase. Both transient hypercoagulability associated with heparin withdrawal and continuous thrombin generation over a longer term related to the underlying disease may explain the rebound in clinical events. Longer duration of combined antiplatelet and anticoagulant treatments, e.g., until healing of the culprit lesion or even until stabilization of vulnerable, yet nondisrupted plaques, may improve long-term clinical outcome.

Increased circulating plasminogen activator inhibitor-1 in patients with patent femoro-distal venous bypass

Veins used for arterial bypass grafting undergo wall remodeling when exposed to altered flow, which may affect fibrinolytic mechanisms and subsequently the fate of the graft. Our aim was to study the extent of blood coagulation and fibrinolysis activation in 27 patients with patent grafts two years after femoro-distal bypass surgery. The two matched control groups included 10 and 19 conservatively treated patients having similar degree of arterial insufficiency (mean ankle/brachial blood pressure index) as the bypass group pre- and post-operatively, respectively. Plasma samples for coagulation and fibrinolysis activation were determined using ELISA and chromogenic assays. When compared with the control groups circulating tissue-type plasminogen activator antigen, and especially plasminogen activator inhibitor type-1, PAI-1 antigen and activity were significantly increased, the mean increase ranging between 54% and 140% in the bypass group. Thrombin-antithrombin III complex, fibrinogen, and C-reactive protein, did not differ, while triglycerides were elevated in the bypass group. Ten patients in the bypass group were insulin resistant, but this did not explain the differences in the fibrinolytic parameters between the bypassed and control patients. Patients with peripheral vein grafts had upregulation of PAI-1 in their circulation implying reduced fibrinolytic capacity. Increased PAI-1, a risk factor for venous thrombosis, might reflect developing intimal hyperplasia, and it remains to be studied whether upregulation of PAI-1 in venous grafts associates with graft failure.