Progressive intermittent claudication is associated with impaired fibrinolysis

Coagulation biomarkers for ischemic stroke

A State of the Art lecture titled "coagulation biomarkers for ischemic stroke" was presented at the International Society on Thrombosis and Haemostasis (ISTH) Congress in 2022. Ischemic stroke (IS) is a common disease with major morbidity and mortality. It is a challenge to determine which patients are at risk for IS or have poor clinical outcome after IS. An imbalance of coagulation markers may contribute to the progression and prognosis of IS. Therefore, we now discuss studies on the association of selected coagulation biomarkers from the hemostasis, inflammation, and immunothrombosis systems with the risk of IS, stroke severity at the acute phase, and clinical outcome after treatment. We report on coagulation biomarker-induced risk of IS, stroke severity, and outcomes following IS derived from prospective population studies, case-control studies, and acute-phase IS studies. We found indications that many coagulation and inflammation biomarkers are associated with IS, but it is early to conclude that any of these biomarkers can be applied in a therapeutic setting to predict patients at risk of IS, stroke severity at the acute phase, and clinical outcome after treatment. The strongest evidence for a role in IS was found for beta-thromboglobulin, von Willebrand factor, factor VIII, fibrinogen, thrombin-activatable fibrinolysis inhibitor, D-dimer, and neutrophil extracellular traps, and therefore, they are promising candidates. Further research and validation in large-size populations using well-defined study designs are warranted. Finally, we provide a selection of recent data relevant to this subject that was presented at the 2022 ISTH Congress.

Regular Resistance Training Enhances Fibrinolytic Potential but Does Not Affect Coagulation

PURPOSE

This study aimed to identify effects of an 8-wk, whole-body RT program on coagulation and fibrinolysis.

METHODS

Sixteen healthy women and men (23 ± 5 yr) completed an RT program three times per week for 8 wk. Exercises included 2-3 sets of 8-12 repetitions performed at approximately 60%-80% of a one repetition maximum. Strength, body composition, and body circumferences were assessed before and after training. Plasma samples were obtained before and after training, and analyzed for active tissue plasminogen activator (tPA activity), total tissue plasminogen activator (tPA antigen), active plasminogen activator inhibitor-1 (PAI-1 activity), total plasminogen activator inhibitor-1 (PAI-1 antigen), fibrinogen, and coagulation factors VII (FVII) and VIII (FVIII).

RESULTS

Significant increases in lean mass, arm and thigh circumferences, maximal chest press (PRE: 57.8 ± 37.5 kg, POST: 73.3 ± 43.2 kg), and leg press (PRE: 189.5 ± 96.0 kg, POST: 256.7 ± 97.9 kg) were observed (P < 0.05 for all). PAI-1 activity (PRE: 20.3 ± 32.5 IU·mL-1, POST 9.5 ± 20.9 IU·mL-1) and PAI-1 antigen decreased (PRE: 10.2 ± 9.0 ng·dL-1, POST: 7.2 ± 5.7 ng·dL-1; both, P < 0.05). No change in tPA activity or tPA antigen occurred. Fibrinogen, FVII, and FVIII did not change after training.

CONCLUSIONS

Inhibition of fibrinolysis was decreased after training, and coagulation was unaffected. These results suggest that regular RT may beneficially influence the risk of a thrombotic event. More research is warranted to understand the mechanisms through which RT affects hemostasis.

Tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in patients with symptomatic lower extremity artery disease

BACKGROUND

Lower extremity artery disease (LEAD) involves progressive arterial narrowing manifested by intermittent claudication (IC). LEAD entails endothelial dysfunction and fibrinolytic disorders. In the current study, we analyze the selected parameters of the fibrinolytic system in the blood of patients with symptomatic LEAD depending on clinical parameters.

METHODS

The test group was comprised of 80 patients with diagnosis of LEAD based on Ankle-Brachial Index (ABI) test (27 female/53 male) with an average age of 63.5±9 years. The control group included 30 healthy, non-smoking volunteers (10 female/20 male), with the median age of 56±6 years. The research material - venous blood - was sampled to determine the concentrations of tissue-type plasminogen activator (t-PA Ag), plasminogen activator inhibitor type 1 (PAI-1 Ag), D-dimer, fibrinogen, and platelet count (PLT).

RESULTS

We found elevated concentrations of t-PA Ag, PAI-1 Ag, D-dimer, and fibrinogen in the plasma of subjects with symptomatic LEAD. Various stages of the Fontaine classification demonstrated a gradual, statistically significant increase in the concentrations of fibrinogen and PLT count as the disease progressed. More so, in the subgroup of LEAD patients aged ≥65 years, we observed significantly higher levels of D-dimer than in the group of younger subjects. In addition to that, the LEAD group demonstrated negative correlations of IC distance, fibrinogen concentrations, and PLT count, negative correlations of ABI at rest and concentrations of D-dimer and PLT count, as well as positive correlations between age and D-dimer levels.

CONCLUSIONS

High t-PA Ag concentrations in LEAD patients suggest damage to the endothelium which comprises the main source of this factor. With high PAI-1 Ag levels, inactive fibrinolytic t-PA-PAI-1 complexes are formed. Increasing fibrinogen concentrations at the subsequent stages in accordance with the Fontaine classification, indicate increasing inflammation. Moreover, heightened values of D-dimer reflect an increased secondary fibrinolysis activation as patients get older and impaired extremity vascularization, manifested by the decreasing ABI, progresses.

Hemostatic Adaptations to High Intensity Interval Training in Healthy Adult Men

Regular exercise is theorized to reduce cardiovascular risk by attenuating coagulation and augmenting fibrinolysis. However, these adaptations have not been consistently observed during traditional exercise programs. The purpose of this study was to examine hemostatic adaptations in healthy men following four (4W) and eight (8W) weeks of high intensity interval training. Twenty-one men (age=25±1 y; body mass index=26.5±6.4 kg/m²) completed eight weeks, three days/week of high intensity interval training on a cycle ergometer. Activated partial thromboplastin time, prothrombin time, and plasma concentrations of thrombin-antithrombin III, fibrinogen, tissue plasminogen activator, and plasminogen activator inhibitor-1 were assessed at baseline (BL), 4W, and 8W. Repeated measures ANOVA were used to determine potential effects of training. There were no significant changes observed for activated partial thromboplastin time (BL=43.3±5.5, 4W=43.2±5.1, 8W=44.2±6.4 s); prothrombin time (BL=13.2±0.9, 4W=13.0±0.6, 8W=13.1±0.8 s); thrombin-antithrombin III (BL=6.0±2.3, 4W=5.8±2.3, 8W=5.6±3.1 ng/mL); tissue plasminogen activator (BL=9.7±3.3, 4W=9.4±3.2, 8W=8.7±2.8 ng/mL); and plasminogen activator inhibitor-1 (BL=19.0±17.5, 4W=19.3±17.0, 8W=18.9±18.9 ng/mL) (all p>0.05). Fibrinogen was significantly lower at 4W (238.6±70.3 mg/dL) compared to BL (285.0±82.1 mg/dL; p<0.05) and 8W (285.3±83.2 mg/dL; p<0.05). These findings indicate that eight weeks of high intensity interval training does not influence coagulation potential and/or stimulate fibrinolysis.

Caffeine Augments the Prothrombotic but Not the Fibrinolytic Response to Exercise

Caffeine, a popular ergogenic supplement, induces neural and vascular changes that may influence coagulation and/or fibrinolysis at rest and during exercise.

PURPOSE

The purpose of this study was to assess the effect of a single dose of caffeine on measures of coagulation and fibrinolysis before and after a single bout of high-intensity exercise.

METHODS

Forty-eight men (age, 23 ± 3 yr; body mass index, 24 ± 3 kg·m) completed two trials, with 6 mg·kg of caffeine (CAFF) or placebo (PLAC), in random order, followed by a maximal cycle ergometer test. Plasma concentrations of fibrinogen, factor VIII antigen, active tissue plasminogen activator (tPA:c), tissue plasminogen activator antigen (tPA:g), and active plasminogen activator inhibitor-1 (PAI-1:c) were assessed at baseline and immediately after exercise.

RESULTS

Exercise led to significant changes in tPA:c (Δ 8.5 ± 4.36 IU·mL for CAFF, 6.6 ± 3.7 for PLAC), tPA:g (Δ 2.4 ± 3.2 ng·mL for CAFF, 1.9 ± 3.1 for PLAC), fibrinogen (Δ 30.6 ± 61.4 mg·dL for CAFF, 28.1 ± 66.4 for PLAC), and PAI-1:c (Δ -3.4 ± 7.9 IU·mL for CAFF, -4.0 ± 12.0 for PLAC) (all P < 0.05), but no effect of condition or time-condition interactions were observed. Main effects of time, condition, and a significant time-condition interaction were observed for factor VIII, which increased from 1.0 ± 0.4 IU·mL to 3.3 ± 1.3 IU·mL with CAFF and 1.0 ± 0.4 IU·mL to 2.4 ± 0.9 IU·mL with PLAC.

CONCLUSIONS

Coagulation potential during exercise is augmented after caffeine intake, without a similar increase in fibrinolysis. These results suggest caffeine intake may increase risk of a thrombotic event during exercise.

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.

Antithrombotic therapy in peripheral artery disease

Antiplatelet agents are recommended for the reduction of major adverse cardiovascular events among all patients with symptomatic peripheral artery disease. However, the optimal antiplatelet regimen and duration of therapy in peripheral artery disease (PAD) remains unclear, largely due to limited and conflicting data in this patient population. This article reviews current data on antithrombotic therapy in PAD and discusses the implications of this data for current practice and future research.

Sedentary behavior is associated with impaired biomarkers in claudicants

OBJECTIVE

Time spent in sedentary behavior has been associated with worse inflammation and cardiometabolic biomarkers in various populations. However, the association between time spent in sedentary behavior and biomarkers remains unknown in patients with intermittent claudication. The aim of the current study was to analyze the relationship between sedentary behavior and inflammatory and cardiometabolic biomarkers in patients with symptomatic peripheral arterial disease (PAD).

METHODS

The sample included 297 patients with intermittent claudication. Sedentary behavior was assessed using a step activity monitor. Biomarkers of inflammation, oxidative stress, lipid profile, insulin resistance, and endogenous fibrinolysis were assessed. Demographic data, body mass index, physical activity status, and measures of severity of PAD (ankle-brachial index, peak walking time, and ischemic window) also were obtained.

RESULTS

Time spent in sedentary behavior was related with high-sensitivity C-reactive protein (b = 0.187; P = .005), glucose (b = 0.238; P < .001), fibrinogen (b = 0.167; P = .017), plasminogen activator inhibitor 1 activity (b = 0.143; P = .036), and high-density lipoprotein cholesterol (b = -0.133; P = .029). After adjustment for sex, age, physical activity status, body mass index, and severity of PAD, sedentary behavior remained related with high-sensitivity C-reactive protein (b = 0.170; P = .015), glucose (b = 0.178; P = .004), fibrinogen (b = 0.189; P = .010), and high-density lipoprotein cholesterol (b = -0.128; P = .032).

CONCLUSIONS

Time spent in sedentary activities was associated with worse inflammatory and cardiometabolic profile in patients with intermittent claudication.

Ischaemia-reperfusion injury impairs tissue plasminogen activator release in man

AIMS

Ischaemia-reperfusion (IR) injury causes endothelium-dependent vasomotor dysfunction that can be prevented by ischaemic preconditioning. The effects of IR injury and preconditioning on endothelium-dependent tissue plasminogen activator (t-PA) release, an important mediator of endogenous fibrinolysis, remain unknown.

METHODS AND RESULTS

Ischaemia-reperfusion injury (limb occlusion at 200 mmHg for 20 min) was induced in 22 healthy subjects. In 12 subjects, IR injury was preceded by local or remote ischaemic preconditioning (three 5 min episodes of ipsilateral or contralateral limb occlusion, respectively) or sham in a randomized, cross-over trial. Forearm blood flow (FBF) and endothelial t-PA release were assessed using venous occlusion plethysmography and venous blood sampling during intra-arterial infusion of acetylcholine (5-20 µg/min) or substance P (2-8 pmol/min). Acetylcholine and substance P caused dose-dependent increases in FBF (P<0.05 for all). Substance P caused a dose-dependent increase in t-PA release (P<0.05 for all). Acetylcholine and substanceP-mediated vasodilatation and substanceP-mediated t-PA release were impaired following IR injury (P<0.05 for all). Neither local nor remote ischaemic preconditioning protected against the impairment of substance P-mediated vasodilatation or t-PA release.

CONCLUSION

Ischaemia-reperfusion injury induced substanceP-mediated, endothelium-dependent vasomotor and fibrinolytic dysfunction in man that could not be prevented by ischaemic preconditioning.

CLINICAL TRIAL REGISTRATION INFORMATION

Reference number: NCT00789243, URL: http://clinicaltrials.gov/ct2/show/NCT00789243?term=NCT00789243&rank=1.

High thrombin activatable fibrinolysis inhibitor levels are associated with an increased risk of premature peripheral arterial disease

BACKGROUND

Previous studies suggested that hypofibrinolysis is associated with increased risk of peripheral arterial disease. Thrombin activatable fibrinolysis inhibitor (TAFI) has been identified as an important inhibitor of fibrinolysis. The aim of our study was to assess the role of TAFI in young patients with peripheral arterial disease.

METHODS

In a single-center case-control study we measured plasma TAFI antigen levels and functional TAFI in consecutive young patients (men 18-45 years and women 18-55 years) with a first manifestation of peripheral arterial disease and compared these with a population-based control group.

RESULTS

A total of 47 peripheral arterial disease patients and 141 controls (mean age 43) were included. Intact TAFI antigen levels were significantly higher in patients with peripheral arterial disease (112.4±21.1%) than in controls (104.9±19.9%, p=0.03). The risk of peripheral arterial disease increased with 18% (OR 1.18; CI 1.01-1.34) per 10% increase of TAFI antigen. Functional TAFI levels were slightly higher in patients compared to controls, however this difference was not significant. For individuals with the highest functional TAFI levels, above the 90th percentile, the increased risk for peripheral arterial disease was most pronounced (OR 3.1; CI 1.02-9.41).

CONCLUSION

High TAFI levels are associated with increased risk of premature peripheral arterial disease.

Plasminogen activator inhibitor-1 (PAI-1): a key factor linking fibrinolysis and age-related subclinical and clinical conditions

INTRODUCTION

The close relationship existing between aging and thrombosis has growingly been studied in this last decade. The age-related development of a prothrombotic imbalance in the fibrinolysis homeostasis has been hypothesized as the basis of this increased cardiovascular and cerebrovascular risk. Fibrinolysis is the result of the interactions among multiple plasminogen activators and inhibitors constituting the enzymatic cascade, and ultimately leading to the degradation of fibrin. The plasminogen activator system plays a key role in a wide range of physiological and pathological processes.

METHODS

Narrative review.

RESULTS

Plasminogen activator inhibitor-1 (PAI-1) is a member of the superfamily of serine-protease inhibitors (or serpins), and the principal inhibitor of both the tissue-type and the urokinase-type plasminogen activator, the two plasminogen activators able to activate plasminogen. Current evidence describing the central role played by PAI-1 in a number of age-related subclinical (i.e., inflammation, atherosclerosis, insulin resistance) and clinical (i.e., obesity, comorbidities, Werner syndrome) conditions is presented.

CONCLUSIONS

Despite some controversial and unclear issues, PAI-1 represents an extremely promising marker that may become a biological parameter to be progressively considered in the prognostic evaluation, in the disease monitoring, and as treatment target of age-related conditions in the future.

Does endothelial dysfunction contribute to the clinical status of patients with peripheral arterial disease?

Peripheral arterial disease leads to lower extremity ischemia and limb loss, and is linked to cardiovascular events. The anatomical extent of lower extremity atherosclerosis fails to fully explain ischemic symptoms or predict the development of critical limb ischemia. Endothelial dysfunction is known to contributed to the pathogenesis and clinical expression of coronary artery disease, but the importance of endothelial dysfunction in peripheral arterial disease remains incompletely understood. Endothelial dysfunction could contribute to lower extremity ischemia by impairing blood flow responses to ischemia, collateral formation and arterial remodelling, and by promoting vasospasm, thrombosis, plaque rupture and lesion progression. There is a need for additional studies examining the contribution of endothelial dysfunction to the pathogenesis of peripheral arterial disease, and the potential role of endothelial dysfunction as a surrogate marker with utility in the management of patients.

Percutaneous treatment of peripheral vascular disease: the role of diabetes and inflammation

Peripheral arterial disease (PAD) is a growing health problem for many Americans and often occurs along with other cardiovascular risk factors, including diabetes mellitus (DM), low-grade inflammation, hypertension, and lipid disorders. Intermittent claudication (IC), an early manifestation of PAD, commonly leads to reduced quality of life for patients who are limited in their ambulation. While recent wide adoption of percutaneous peripheral interventional (PPI) techniques has increased the number patients being aggressively treated for IC, the overall effectiveness of PPI for the treatment of IC is not well known, especially for DM patients who have both hemodynamic and functional obstacles to treatment success. This review is designed to illustrate how treatment outcomes for IC can be measured by different modalities and how diabetes and inflammation can influence those outcomes. In the setting of greater concern for health care resources and clinical accountability, better understanding of treatment outcomes and efficacy will help us manage these complex challenges.

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.

Antithrombotic treatment for peripheral arterial disease

CONTEXT

Patients with peripheral arterial disease (PAD) bear a substantial risk for vascular events in the coronary, cerebral and peripheral circulations. In addition, this disorder is associated with a systemic milieu characterised by ongoing platelet activation and heightened thrombogenesis.

OBJECTIVE

To determine the optimal antithrombotic prophylaxis for patients with PAD.

DATA SOURCES

Using terms related to PAD and antithrombotic agents, we searched the following databases for relevant articles: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, the National Institutes of Health Clinical Trials Database, Web of Science, and the International Pharmaceutical Abstracts Database (search dates: 1 January 1990 to 1 January 2007). Additional articles were identified from cardiovascular and vascular surgery conference proceedings, bibliographies of review articles, and personal files.

STUDY SELECTION

We focused on randomised trials, systematic reviews and consensus guidelines of antithrombotic therapies for PAD.

DATA EXTRACTION

Detailed study information was abstracted by each author working independently.

RESULTS

Multiple studies show that patients with PAD manifest platelet hyperaggregability, increased levels of soluble platelet activation markers, enhanced thrombin generation and altered fibrinolytic potential. Many of these markers predict subsequent cardiovascular events. Available randomised trials and meta-analyses show that most available antithrombotic agents prevent major cardiovascular events and death in patients with PAD, including aspirin, aspirin/dipyridamole, clopidogrel, ticlopidine, picotamide and oral anticoagulants.

CONCLUSIONS

Although the most favourable risk-benefit profile, cost-effectiveness and overall evidence base supports aspirin in this setting, we provide scenarios in which alternatives to aspirin should be considered.

Relationship of smoking and smoking cessation with ankle-to-arm blood pressure index in elderly Japanese men

BACKGROUND

Cigarette smoking is associated with an increased risk of peripheral arterial disease, but the relationship between smoking cessation and preclinical peripheral atherosclerosis is uncertain.

DESIGN AND METHODS

A cross-sectional, population-based study to examine the effect of smoking and smoking cessation on the prevalence of peripheral arterial disease among 1215 men aged 60-79 years in two Japanese communities in 1999-2000. The ankle-to-arm systolic blood pressure index (AAI) was used as an estimate of the presence of peripheral atherosclerosis.

RESULTS

The mean AAI correlated inversely and linearly with smoking status and pack-years of smoking. The multivariate prevalence odds ratio [95% confidence interval (CI)] of low AAI (< 0.90) compared with never-smokers was 3.7 (95% CI 1.1-12.7) for current smokers and 4.2 (95% CI 1.2-14.6) for men with 45 or more pack-years of smoking. In men who have quit smoking for 20 years or more, the mean AAI was higher and the prevalence of low AAI (< 0.90) was lower than those of current smokers, but similar to those of never-smokers.

CONCLUSIONS

Our results confirm that current smoking and pack-years of smoking correlate with the presence of peripheral artery disease. The results suggest that smoking cessation for 20 years or more is associated with the regression of atherosclerosis in peripheral arteries. This finding needs to be confirmed by a prospective study.

Supporting a call to action for peripheral artery disease: Insights from two prospective clinical registries

BACKGROUND

Patients affected by peripheral arterial disease (PAD) incur a heightened risk of adverse cardiovascular events, including stroke, myocardial infarction, and vascular mortality. We examined risk factors, medications, and prognosis of outpatients with PAD enrolled in two national, prospective, practice-based Canadian registries that encompassed 484 physician practices: the Vascular Protection and Guideline Oriented Approach in Lipid Lowering registries.

METHODS

The 2 registries were combined to analyze 9810 patients with vascular disease, diabetes mellitus, or age 65 years or older plus at least 2 additional cardiovascular risk factors. Risk factors, medications, and major cardiovascular events were recorded at baseline and again at 6 months' follow-up.

RESULTS

Compared with patients without PAD (n = 8303), those with PAD (n = 1507) had substantially worse risk factor profiles and were more likely to have coexisting coronary or cerebrovascular disease. Both groups received high rates of treatment with evidence-based therapies, including antiplatelet drugs, statins, and angiotensin-converting enzyme inhibitors. Despite this, patients with PAD had a nearly twofold higher risk of major cardiovascular events at 6 months than non-PAD patients (7.3% vs 4.1%; P < .0001). After adjustment for multiple confounding factors, the presence of PAD at baseline continued to predict a heightened risk of adverse vascular sequelae (odds ratio, 1.54; 95% confidence interval, 1.18-2.01; P < .0001).

CONCLUSIONS

These data support a strong relationship between PAD and worsened vascular prognosis that is independent of both conventional vascular risk factors and concomitant cardiovascular disease. The presence of PAD should therefore provide a clear impetus for intensive risk factor modification and use of preventive medical therapy in affected patients.

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.

The constitutive procoagulant and hypofibrinolytic state in patients with intermittent claudication due to infrainguinal disease significantly improves with percutaneous transluminal balloon angioplasty

BACKGROUND

Patients with intermittent lower limb claudication (IC) exhibit a prothrombotic diathesis that is acutely exacerbated by exercise. This may occur because of ischemia/reperfusion injury within the leg muscles during walking and may contribute to the increased risk of thrombotic vascular events in this group of patients. This randomized study compared the effect of lower limb revascularization by percutaneous transluminal balloon angioplasty (PTA), supervised exercise, and best medical therapy (BMT) alone on this prothrombotic state.

METHODS

Twenty-three patients (16 men and 7 women; median age, 67 years; range, 57-77 years) with IC due to infrainguinal disease were randomized to receive BMT alone (n = 7), BMT plus PTA (n = 9), or BMT plus supervised exercise (n = 7) as part of the Health Technology Assessment-funded EXercise vs Angioplasty in Claudication Trial (EXACT). Patients were assessed at baseline and at 3 and 6 months. Thrombin-antithrombin complex (TAT) was determined as a marker of thrombin generation, and plasminogen activator inhibitor (PAI) antigen was determined as a marker of fibrinolysis. Increased TAT indicates a procoagulant state, and increased PAI antigen indicates a hypofibrinolytic state.

RESULTS

At 6 months, subjects randomized to BMT plus PTA demonstrated a significant improvement in ankle-brachial pressure index (P = .013) and maximal walking distance (P = .008), a significant decline in resting thrombin generation (median [interquartile range] TAT, 6.4 microg/L [2.7-13.5 microg/L] to 1.5 microg/L [0.3-2.9 microg/L]; P = .038), and an improvement in resting fibrinolysis (median [interquartile range] PAI-1, 10.0 ng/mL [1.0-20.5 ng/mL] to 1.0 ng/mL [1.0-14.8 ng/mL]; P = .043). There was no significant change in any of these parameters in patients randomized to BMT plus supervised exercise or to BMT alone.

CONCLUSIONS

The addition of lower limb revascularization by PTA to BMT in patients with IC due to infra-inguinal disease results in a medium-term improvement in the resting procoagulant and hypofibrinolytic state. This may translate into a reduction in morbidity and mortality from thrombotic vascular events in this group of patients.

Association of the fibrinolytic system and hemorheology with symptoms in patients with carotid occlusive disease

BACKGROUND AND OBJECTIVES

The risk of stroke caused by a symptomatic high-grade carotid stenosis (CS) is high. Disturbed balance between the procoagulant and fibrinolytic activity in blood associated with unfavorable hemorheology could render CS symptomatic. We wanted to assess whether hemostatic and fibrinolytic plasma markers as well as basic indicators of hemorheology differentiate asymptomatic and symptomatic patients with a high-grade CS and whether they are associated with the macroscopic appearance of the plaque and the rate of microembolization.

METHODS

We recruited 92 consecutive consenting patients referred to the neurological or the surgical department of our university teaching hospital for treatment of their high-grade CS. Blood samples were collected before surgery for determination of prothrombin fragments F1 and 2, thrombin-antithrombin complex, tissue-type plasminogen activator (tPA) activity and antigen, plasminogen activator inhibitor-1 (PAI-1) activity and antigen, D-dimer, homocysteine, fibrinogen, in plasma, and hematocrit in blood, and the patients underwent transcranial Doppler ultrasonology for evaluation of microembolic signals (MES).

RESULTS

Patients with symptomatic plaques had higher hematocrit levels (p = 0.04), as well as trends for higher tPA antigen and MES rate (p = 0.07). Hematocrit, tPA antigen, and PAI-1 antigen and activity were positively correlated with the degree of stenosis. Ulceration was more common in symptomatic plaques but did not reflect variables of hemostasis or fibrinolysis. In multivariate analysis, tPA antigen and hematocrit were risk factors for a symptomatic high-grade stenosis.

CONCLUSION

Mediators of fibrinolysis and unfavorable hemorheology may contribute to the development of a symptomatic disease in patients with a high-grade CS.

Associations between cigarette smoking, pipe/cigar smoking, and smoking cessation, and haemostatic and inflammatory markers for cardiovascular disease

AIMS

To examine the associations between cigarette smoking, pipe/cigar smoking, and years since quitting smoking, and inflammatory and haemostatic markers.

METHODS AND RESULTS

A study in 2920 men aged 60-79 with no history of myocardial infarction, angina, stroke, or diabetes, and who were not on warfarin, from general practices in 24 British towns. After adjustment for other major cardiovascular risk factors, compared with never smokers, current cigarette smokers showed significantly higher levels of C-reactive protein (2.53 vs. 1.35 mg/L), white cell count (7.92 vs. 6.42 x 10(9)/L), and fibrinogen (3.51 vs. 3.13 g/L). They also showed higher levels of haematocrit, blood and plasma viscosity, tissue plasminogen activator antigen, and fibrin D-dimer, and lower levels of albumin. Primary pipe/cigar smokers showed levels similar to never smokers. Ex-cigarette smokers and secondary pipe/cigar smokers showed intermediate levels although secondary pipe/cigar smokers showed higher odds of having elevated white cell count and fibrinogen than ex-cigarette smokers. Most inflammatory and haemostatic levels improved within 5 years of smoking cessation but took over 20 years to revert to levels of never smokers.

CONCLUSION

These findings suggest that activation of inflammation and haemostasis may be potential mechanisms by which cigarette and pipe/cigar smoking increase cardiovascular risk.

Virchow’s Triad Revisited: Blood Constituents

An update of Virchow's triad for thrombogenesis can be considered by reference to abnormalities in the endothelium/endocardium ('abnormal vessel wall'), abnormalities of haemorhelogy and turbulence at bifurcations,atheroma at vessel wall ('abnormal bloodflow') and abnormalities in platelet as well as the coagulation and fibrinolytic pathways ('abnormal blood constituents'). The constituents of the blood are many and varied, but soluble coagulation factors (such as fibrinogen and tissue factor) and cells (such as platelets)are clearly important. Clearly, 'a continuum exists between health, 'statistically' increased haemostatic abnormalities in prothrombotic or hypercoagulable states and 'overtly' increased clotting in acute thrombosis.Thus, the patients with the highest levels of the markers appear to be the highest risk of disease progression,and if so, a panel of 'high risk' blood constituent indices (platelet and coagulation markers) may potentially give a composite score of risk, and may be a useful tool in predicting subjects at highest risk. Further longitudinal studies are clearly required. There is no doubt that Virchow would be impressed on how his classical triad has expanded to encompass the wide range of pathophysiological processes leading to thrombogenesis.

Exercise training enhances endogenous fibrinolysis in peripheral arterial disease

PURPOSE

Acute clinical events resulting from atherosclerosis (myocardial infarction, stroke) are associated with impaired endogenous fibrinolysis, the system by which the body lyses inappropriately formed thrombus. Endurance exercise training improves fibrinolysis in normal subjects and those with coronary artery disease. The hypothesis of this study was that exercise training would improve fibrinolysis in subjects with peripheral arterial disease (PAD).

METHODS AND RESULTS

Twenty-one men with intermittent claudication (IC-EX) underwent treadmill exercise training for 6 months. Twenty age-matched male subjects with IC were followed for the same period (IC-NONEX). Fibrinolytic activity was measured prior to entry into exercise or "usual care," and at the completion of the study period. Fibrinolysis was quantified by measurement of the activity levels of tissue plasminogen activator (tPA, the activator of fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1), using an amidolytic method. Fibrinolysis, quantified as increased PAI-1 activity, was reduced in both claudicant groups relative to healthy controls at baseline. After 6 months of exercise, subjects in the IC-EX group experienced significant improvements in fibrinolytic activity, manifested as a 23% decrease in PAI-1 activity and a 28% increase in tPA activity. No changes occurred in the IC-NONEX group. In the IC-EX group, subjects with the highest initial PAI-1 values experienced the greatest decreases in PAI-1 activity and thus the greatest benefit from exercise.

CONCLUSIONS

Patients with PAD have impaired fibrinolytic activity, manifested primarily as increases in the inhibitor of fibrinolysis, PAI-1. Six months of exercise training reduced these impairments, and may serve as an intervention to reduce cardiovascular mortality and morbidity in these patients.

Influence of fibrinogen and hematocrit on the early outcome of angioplasty in patients with PAOD

PURPOSE

To evaluate any correlation of fibrinogen and hematocrit with the early success of balloon angioplasty for peripheral arterial occlusive disease (PAOD) and compare the outcomes of angioplasty in diabetic and nondiabetic patients.

METHODS

From November 1997 through October 2000, 330 patients (246 men; mean age 63.6+/-10.9 years; 221 nondiabetic, 109 diabetic) with known PAOD were treated with percutaneous procedures. The majority of patients (239, 72.4%) were Fontaine stage IIa or IIb; the remaining (91, 27.6%) had critical limb ischemia (Fontaine stages III and IV). Fibrinogen and hematocrit assays were performed on all patients upon admission, and the results were then correlated with early angioplasty success.

RESULTS

With advancing PAOD stage, fibrinogen concentrations increased significantly in both nondiabetic (p<0.006) and diabetic (p<0.02) patients, while angioplasty success rates declined by a factor of 3 in nondiabetics and 2 in diabetics. There was a significantly stronger association between low fibrinogen values and successful interventions relative to unsuccessful interventions (p<0.048). Interestingly, compared with nondiabetics, the angioplasty success rate in diabetics was associated with significantly higher fibrinogen levels (p<0.044) and lower hematocrit (p<0.022).

CONCLUSIONS

Our findings appear to indicate that hemorheological factors, such as fibrinogen and hematocrit, can affect early angioplasty success. Moreover, high fibrinogen concentrations appear to be detrimental to early angioplasty success. Interestingly, low hematocrit levels in diabetics may partially offset the negative effects of hyperfibrinogenemia.

Activation of Coagulation and Fibrinolytic Systems in Patients with CLI is not Normalized after Surgical Revascularisation

OBJECTIVE

To study the activation of coagulation and fibrinolysis before, during and after surgical revascularisation in patients with critical limb ischemia (CLI).

DESIGN

Prospective clinical study.

MATERIALS AND METHODS

Forty patients with CLI underwent femoro-popliteal or femoro-distal reconstruction and were compared to a control-group. Measurements of prothrombin-fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) assessed activation of coagulation. Fibrinolysis was determined by tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1) and fibrin degradation product (D-dimer). The inflammatory mediators: Interleukin 2 receptor (IL-2-rec), Interleukin 6 (IL-6), Interleukin 10 (IL-10) and Monocyte chemoattractant protein 1 (MCP-1) was also analysed.

RESULTS

Patients (in 35 of the 40 reconstruction was possible) were operated upon using either vein (n=23) or ePTFE (n=12) grafts. Patients with CLI had a preoperative prothrombotic state as indicated by high TAT-levels and also ongoing fibrinolysis with high levels of t-PA and D-dimer. After reperfusion an ongoing prothrombotic state for the first week was demonstrated. A significant as well as defective fibrinolysis was also seen with increased levels of tPA and D-dimer unopposed by PAI-1 after one week and also after 30 days. Increased levels of inflammatory mediators IL-6, IL-10 and MCP-1 was observed after reperfusion and normalised after 30 days.

CONCLUSION

This study demonstrates significant disturbances of both the coagulation and fibrinolytic systems before, during and after revascularisation for CLI. This was accompanied by release of inflammatory mediators. A prothrombotic state and increased fibrinolysis were evident also 30 days after successful revascularisation.

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.

Coagulation and Fibrinolytic Responses to Manual versus Automated Snow Removal

PURPOSE

The purpose of this study was to assess coagulation and fibrinolytic responses to snow removal.

METHODS

Thirteen healthy male subjects (age = 26 +/- 5 yr, height = 179.0 +/- 7.0 cm, weight = 78.7 +/- 16.1 kg, .VO2max = 54.7 +/- 8.9 mL.kg-1.min-1) underwent maximal treadmill stress testing (TM), 10 min of snow shoveling (SS), and 10 min of snow removal using an automated snow thrower (ST). Blood was collected immediately before and after each test and analyzed for von Willebrand Factor antigen (vWF:ag), tissue plasminogen activator (tPA) antigen, and plasminogen activator inhibitor-1 (PAI-1) activity. Data were analyzed using a two-factor repeated-measures analysis of variance.

RESULTS

vWF:ag significantly increased during TM (84.7 +/- 21.7% normal preexercise, 149.0 +/- 45.6% normal postexercise) but not SS or ST. TM resulted in significant increases in tPA antigen (6.54 +/- 2.76 ng.mL-1 preexercise, 21.39 +/- 10.56 ng.mL-1 postexercise) and both SS and TM caused significant reductions in PAI-1 activity (SS = 15.1 +/- 3.8 AU.mL-1 preexercise, 13.2 +/- 4.3 AU.mL-1 postexercise; TM = 15.3 +/- 3.6 AU.mL-1 preexercise, 10.5 +/- 5.3 AU.mL-1 postexercise). Postexercise PAI-1 activity was significantly lower for TM versus SS. tPA antigen was unchanged after SS and ST, and PAI-1 activity was unchanged after ST.

CONCLUSION

vWF:ag is unchanged after self-paced snow shoveling and automated snow removal in young, healthy males. Snow shoveling acutely increases fibrinolytic potential in this population, although not to the degree observed after maximal treadmill exercise.

Association between physical activity and endogenous fibrinolysis in peripheral arterial disease: a cross-sectional study

The purpose of this study was to determine whether daily physical activity was independently related to endogenous fibrinolysis in subjects with peripheral arterial disease (PAD). One hundred and six subjects with peripheral arterial disease (PAD) and intermittent claudication were characterized on the activity level of tissue plasminogen activator (tPA, the activator of fibrinolysis), the activity level of plasminogen activator inhibitor (PAI-1, the inhibitor of fibrinolysis), daily physical activity, ambulatory function, and demographic information. Subjects were separated into low (n = 36), moderate (n = 34), and high (n = 36) physical activity tertiles based on a 48-hour monitoring period with use of an accelerometer. The tPA activity of the low physical activity group (1.30 +/- 0.16 IU/mL) was 21% and 19% lower (p<0.05) than that of the moderate (1.65 +/- 0.18 IU/mL) and the high (1.61 +/- 0.15 IU/mL) physical activity groups, respectively. The PAI-1 activity of the low physical activity group (21.41 +/- 1.14 AU/mL) was 15% and 23% higher than that of the moderate (18.61 +/- 1.34 AU/mL) and the high (17.47 +/- 1.14 AU/mL) physical activity groups, respectively. Group differences in tPA activity and PAI-1 activity persisted after our controlling for group differences in measured and self-reported ambulatory measures. Daily physical activity is related to a more favorable endogenous fibrinolytic profile in PAD subjects with intermittent claudication. Subjects who expend fewer than 175 kcal/day in physical activities (approximately 35 minutes) are particularly susceptible to having a prothrombotic state. Subjects should be encouraged to participate in at least 35 minutes of physical activity each day to enhance fibrinolysis.

Analysis of risk factors for local delivery of low- and intermediate-dose adenovirus gene transfer vectors to individuals with a spectrum of comorbid conditions

In this study we analyze the adverse events and abnormal laboratory parameters following local administration of low (<10(9) particle units) and intermediate (10(9)-10(11) particle units) single and repetitive doses (140 total) of E1(-)E3(-) adenovirus (Ad) gene transfer vectors administered to the respiratory epithelium, solid tumors, skin, myocardium, and skeletal muscle in eight gene transfer trials since April 1993. In the accompanying paper by Harvey et al., (Hum. Gene Ther. 2002; 13:15-63), we conclude that for the total group, no deaths were attributable to the Ad vectors per se, and the incidence of major adverse events likely caused by an Ad vector was 0.7%. The present study analyzes the trials as a group to evaluate risk factors for the adverse events, abnormal values among laboratory parameters, and known deaths. Ten putative risk factors were assessed, including "patient-related" (age, sex, comorbid index and pretherapy anti-Ad antibodies), "vector-related" (dose, route, transgene, and number of vector administrations), and "trial-related" (trial in which the individual was enrolled, and whether surgery was part of the trial). While assessment of each factor individually suggested several possible associations with adverse events, abnormal laboratory parameters, or deaths, multivariate analysis identified only age, comorbid index, and surgery (comorbid index for death; age and surgery for non-death adverse events) as variables significantly associated with increased risk for a major (severity scale 3-4 of 4) adverse event for individuals enrolled in these gene transfer trials. Importantly, multivariate analysis suggested that vector-related parameters, including dose, route, transgene, or number of vector administrations at the doses and routes evaluated in these studies, do not appear to be significant risk factors for a major adverse event. With the caveat that these are phase I, uncontrolled trials, we conclude that (1) there is no definitive risk factor that will clearly predict a major adverse outcome resulting from local administration of low and intermediate doses of Ad gene transfer vectors; and (2) major adverse events in these gene transfer trials are associated primarily with the study population and/or trial procedures, not the Ad vectors themselves. This assessment is consistent with the concept that local administration of low and intermediate doses of Ad gene transfer vectors appears to be well tolerated.

Remnant lipoproteins induce endothelial plasminogen activator inhibitor-1

Remnant lipoproteins (RLPs) accumulate in type III hyperlipoproteinemia, a condition associated with significant cardiovascular morbidity. The effect of RLPs on fibrinolysis is unknown. Our aim was to study the effect of RLPs on endothelial expression of plasminogen activator inhibitor-1 (PAI-1). After 24-h culture of human aortic endothelial cells with RLPs at concentrations of 0 (control), 0.038, or 0.076 mg triglyceride/mL, postculture PAI-1 antigen concentrations were: 870 +/- 80, 1963 +/- 183 (P = 0.005), and 3551 +/- 177 ng/mL (P < 0.001), respectively. Furthermore, after 24-h incubation of endothelial cells with RLPs (0 or 0.076 mg triglyceride/mL), PAI-1 activity increased from 0.667 +/- 0.144 to 1.268 +/- 0.198 U/mL, respectively (P = 0.008) and endothelial PAI-1 mRNA increased to 2.7 +/- 0.66 that of control (P = 0.048). In conclusion, RLPs from patients with type III hyperlipoproteinemia induce endothelial cell PAI-1 expression, which may contribute to a prothrombotic state.

Tissue plasminogen activator, plasminogen activator inhibitor-1, and tissue plasminogen activator/plasminogen activator inhibitor-1 complex as risk factors for the development of a first stroke

BACKGROUND NAD PURPOSE: Abnormalities in the fibrinolytic system have been associated with an increased risk for stroke in a few studies. This study was designed to test whether plasma levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), and tPA/PAI-1 complex could predict a first-ever stroke.

METHODS

The study was an incident case-control study nested within the Västerbotten Intervention Program and the Northern Sweden Monitoring Trends and Determinants in Cardiovascular Disease (MONICA) cohorts. In this study 108 first-ever stroke cases were defined according to the MONICA classification, and 216 controls from the same cohort were randomly selected and matched for age, sex, sampling time, and geographic region.

RESULTS

Stroke occurred on average 30 months after the blood sampling date. The mean plasma concentration of tPA/PAI-1 complex was higher for the stroke cases than for the controls (3.9 versus 3.0 microgram/L). In univariate regression analysis, significantly higher odds ratios were found for the tPA/PAI-1 complex as continuous variable. When divided into quartiles, the odds ratio was 2.74 for the highest quartile compared with the lowest. In the multivariate model, the tPA/PAI-1 complex remained an independent predictor for stroke. Additionally, tPA mass concentration quartiles 3 and 4 showed a significant association with all stroke as outcome. No association was found, however, for PAI-1. In subgroup analysis of cerebral hemorrhage (n=18), the mean tPA/PAI-1 complex level was higher for the cases than for the controls (4.8 versus 3.0 microgram/L), and in multivariate analysis including all controls (n=216), only tPA/PAI-1 complex remained significant.

CONCLUSIONS

This prospective study shows that tPA/PAI-1 complex, a novel fibrinolytic marker, is independently associated with the development of a first-ever stroke, especially hemorrhagic stroke. This finding supports the hypothesis that disturbances in fibrinolysis precede a cerebrovascular event.