Hemostatic factors as predictors of ischemic heart disease and stroke in the Edinburgh Artery Study

D-dimer is not a long-term prognostic marker following acute cerebral ischemia

Recent evidence indicates a possible role of D-dimer in the early diagnosis of ischemic stroke subtypes. Whether D-dimer can also predict the long-term outcome following ischemic stroke is controversial. To define the prognostic role of D-dimer, patients hospitalized after an acute ischemic cerebrovascular event underwent D-dimer measurement (Liatest D-D; normal level < 0.50 microg/ml) on admission and were followed up for recurrent cerebrovascular events, occurrence of other cardiovascular events, and mortality. We enrolled 96 patients (mean age 74.9 years, 42 men). Mean follow-up was 61.5 months; 47 (48.5%) patients died, 23 (48.9%) because of a vascular event. There was no difference in mean D-dimer levels between dead patients and survivors (1.68 and 1.63 microg/ml, P = NS), but the mortality risk was higher with D-dimer of at least 0.50 microg/ml (odds ratio, 5.32; 95% confidence interval, 1.79-15.84). After adjustment for age and stroke subtype, the odds ratio was not significant. Mean D-dimer was similar between patients with and without a new vascular event (1.43 and 1.68 microg/ml, P = NS), and D-dimer of at least 0.50 microg/ml was not predictive of an increased risk of subsequent events. D-dimer levels measured in the acute phase after an acute cerebrovascular event probably do not predict the long-term clinical outcome.

Coagulation and atherothrombotic disease

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

von Willebrand factor, endothelial dysfunction, and cardiovascular disease

von Willebrand factor (VWF), a glycoprotein involved in arterial thrombus formation, is released into the circulation by secretion from endothelial cells. Plasma VWF levels are determined by genetic factors including ABO blood groups and VWF mutations, and by non-genetic factors including aging, impaired nitric oxide production, inflammation, free radical production and diabetes. Plasma VWF levels have been proposed as a risk factor for cardiovascular events. Although they are only weakly associated with the risk of coronary heart disease (CHD) in the general population, they are a more promising CHD risk factor in high-risk populations with previous cardiovascular events, diabetes or old age. However, is it still unclear whether VWF levels directly determine the rate and severity of arterial thrombus formation or whether they merely reflect alteration in other endothelial functions. The future status of VWF levels as a cardiovascular risk factor depends on additional studies on the genetic determinants of both VWF levels and cardiovascular outcomes. Further studies on VWF levels as a predictor of the risk of stroke (rather than CHD) in elderly or other high-risk population are also promising. Such studies could lead to the clinical use of plasma VWF levels to refine the estimation of the cardiovascular risk and of the expected benefit of antithrombotic agents.

Can haematological tests predict cardiovascular risk? The 2005 Kettle Lecture*

The risk of venous or arterial thrombosis is routinely assessed by clinical variables (risk factors) supplemented by measurement of blood lipids and glucose for arterial thrombotic events. Haematological tests that might play a role in risk prediction include haemostatic variables, haematocrit and inflammatory markers (erythrocyte sedimentation rate, plasma viscosity, white cell count). Recent epidemiological studies of these phenotypes and related genotypes are reviewed. For the risk prediction of first venous thrombosis, screening for thrombophilias in 'high-risk' situations does not appear clinically effective or cost-effective; with the possible exception of women considering oral hormone replacement therapy. General screening after a first venous event to predict recurrence (or risk in asymptomatic relatives) does not appear effective; with the possible exception of d-dimer, which requires further study. For risk prediction of first arterial thrombosis, screening adds little to prediction by current clinical risk scores. Screening of persons after a first arterial event, or with atrial fibrillation (e.g. with D-dimer for stroke prediction), requires further study. In conclusion, haematological tests have very limited roles in the prediction of cardiovascular risk, and should only be used according to evidence-based guidelines. The need for management studies is highlighted.

Fibrinolytic risk factor clustering and insulin resistance in healthy male relatives of men with intermittent claudication

BACKGROUND

Raised fibrinolytic factors predict cardiovascular risk in healthy subjects. The aim of this study was to measure fibrinolytic factors and insulin resistance in healthy male first-degree relatives of men with intermittent claudication younger than 65 years.

METHODS

The study compared 165 healthy first-degree relatives with 165 age-, sex- and race-matched control subjects free from a personal or family history of premature cardiovascular disease. Primary outcome measures were plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (tPA) and D-dimer levels. Insulin resistance was estimated by Homeostasis Model Assessment. Clinical and biochemical risk factors were measured and subjects genotyped for the PAI-1 4G/5G polymorphism.

RESULTS

First-degree relatives had significantly higher mean PAI-1 (10.23 versus 7.85 ng/ml; P = 0.024), tPA (9.98 versus 8.29 ng/ml; P < 0.001) and D-dimer levels (56.6 versus 46.1 ng/ml; P = 0.004). They also had significantly higher insulin resistance (1.85 versus 1.53; P < 0.001) and clustered multiple atherogenic risk factors. On multivariate analysis the association between both tPA and D-dimer levels and relative status was independent of other variables.

CONCLUSION

Raised levels of PAI-1, tPA, D-dimer and estimated insulin resistance were present in the healthy male first-degree relatives of men with intermittent claudication. These data support the hypothesis of fibrinolytic risk factor clustering in this high-risk population.

Von Willebrand factor and thrombosis

There is increasing evidence that von Willebrand factor (VWF), an adhesive multimeric protein that has an important function in primary hemostasis and as a carrier of factor VIII, has a pivotal role in thrombogenesis. In fact, while the presence in plasma of unusually large VWF multimers due to a congenital or acquired deficiency of a VWF-cleaving metalloprotease has been implicated in the pathogenesis of thrombotic thrombocytopenic purpura (TTP), high plasma levels of VWF have been associated with a slightly increased risk of arterial thrombosis. With regard to the association between VWF and venous thrombosis, clear conclusions cannot yet be drawn from the conflicting published data. Patients with von Willebrand disease, an inherited hemorrhagic disorder, may also paradoxically experience thrombotic events as a result of interactions among multiple prothrombotic risk factors. After a description of the structure and physiology of VWF, all these aspects are discussed in the present review.

Overview of hemostatic factors involved in atherosclerotic cardiovascular disease

Hemostatic factors associated with the development of cardiovascular disease (CVD) include fibrinogen, von Willebrand factor, tissue plasminogen activator (tPA) antigen, plasminogen activator inhibitor-1 (PAI-1), and factor VII. Each SD increment of these increases the association by 24-30%. Most hemostatic factors are intercorrelated with inflammatory markers [e.g., C-reactive protein (CRP)] and LDL cholesterol. Fibrinogen seems the most fundamental hemostatic risk factor for CVD. The Framingham Study reaffirms the significant linear risk factor trends across fibrinogen tertiles (P< 0.001) for age, body mass index, smoking, diabetes mellitus, total cholesterol, HDL cholesterol, and TG in both sexes. Fibrinogen may also directly increase CVD risk because of its role in platelet aggregation, plasma viscosity, and fibrin formation. Fibrinogen is also an acute-phase reactant that is elevated in inflammatory states. Fibrinogen mediates the thrombogenic effect of other risk factors. Fibrinogen levels increase with the number of cigarettes smoked and quickly fall after smoking cessation. This rapid fibrinogen decline may be a mechanism for CVD risk reduction after smoking cessation. Weight loss is accompanied by reduced fibrinogen. The correlation between fibrinogen and LDL cholesterol suggests that lipid-imposed CVD risk is mediated partly through fibrinogen. Hyperreactive platelets of diabetics may result in part from their increased fibrinogen. Elevated fibrinogen and CRP of unstable angina suggest an acute-phase reaction. Prevalence, case-control, angiographic, and echocardiogram investigations incriminate hemostatic and inflammatory markers as strong independent risk factors for initial and recurrent CVD. Framingham Study data indicate that each SD increase in fibrinogen imposes a 20% independent increment in risk. It may be concluded that fibrinogen and CRP determination may be useful screening tools to identify individuals at added risk for thrombotic complications of CVD.

Antiplatelet Therapy in Stroke Prevention: Present and Future

White platelet-fibrin thrombi often form on roughened endothelial surfaces and unstable arterial plaques. Agents that reduce the tendency of platelets to aggregate, agglutinate, and secrete and to attach to endothelial surfaces have been explored as agents that prevent brain and heart infarction. Aspirin, ticlopidine, clopidogrel, dipyridamole, cilostazol, and glycoprotein llb/llla inhibitors are all used now and have various different modes of action and functions.

Hemostatic factors, inflammatory markers, and progressive peripheral atherosclerosis: the Edinburgh Artery Study

The interplay between inflammatory and hemostatic mechanisms may play a crucial role in the development and progression of atherosclerosis. The authors evaluated the separate and joint associations of hemostatic and inflammatory variables on peripheral atherosclerotic progression in the Edinburgh Artery Study, a population cohort study of 1,592 men and women aged 55-74 years that started in 1987. Levels of fibrinogen, fibrin D-dimer, von Willebrand factor, tissue plasminogen activator antigen, factor VII, prothrombin fragment 1 + 2, urinary fibrinopeptide A, C-reactive protein, and interleukin-6 were measured at baseline. Arm and ankle blood pressures were measured, and atherosclerotic progression was assessed by computing ankle brachial index (ABI) at baseline (1,582 participants) and after 12 years of follow-up (813 participants). Fibrinogen (p = 0.05) and D-dimer (p < or = 0.05) were significantly associated with ABI change independently of baseline ABI and cardiovascular disease risk factors. However, these associations were no longer significant when analyses were adjusted for either C-reactive protein or interleukin-6. Moreover, subjects with higher levels of both D-dimer and interleukin-6 at baseline had the greatest ABI decline. In conclusion, fibrinogen and D-dimer, but not other hemostatic factors, were associated with progressive peripheral atherosclerosis. Since D-dimer and fibrinogen are acute phase reactants, these data support the hypothesis that inflammation is more related to atherosclerosis than is hypercoagulation.

New risk factors for atherosclerosis in hypertension: focus on the prothrombotic state and lipoprotein(a)

Although adequate control of blood pressure is of basic importance in cardiovascular prevention in hypertensive patients, correction of additional risk factors is an integral part of their management. In addition to classical risk factors, epidemiological research has identified a number of other conditions that might significantly contribute to cardiovascular risk in the general population and might achieve specific relevance in patients with high blood pressure. In fact, more than 20% of patients with premature cardiovascular events do not have any of the traditional risk factors and, although effective intervention on blood pressure and additional risk factors has significantly reduced cardiovascular morbidity and mortality, the contribution to stroke, coronary artery disease and renal failure is still unacceptably high. Evaluation of new risk factors may further expand our capacity to predict atherothrombotic events when these factors are included along with the traditional ones in the assessment of global cardiovascular risk in hypertensive patients. Because it could be anticipated that the role of these novel factors will become increasingly evident in the future, researchers with an interest in hypertension and physicians dealing with problems related to cardiovascular prevention should give them appropriate consideration. This review summarizes the basic biology and clinical evidence of two emerging risk factors that are reciprocally related and contribute to the development and progression of organ damage in hypertension: the prothrombotic state and lipoprotein(a).

A Systematic Comparison of the Quality and Volume of Published Data Available on Novel Risk Factors for Stroke versus Coronary Heart Disease

BACKGROUND

To identify new treatments to prevent stroke, it is important that we have reliable data on potential novel risk factors.

METHODS

We studied seven novel vascular risk factors [apo-lipoprotein (b), C-reactive protein, Chlamydia pneumoniae, fibrin-D dimer, fibrinogen, Helicobacter pylori and lipoprotein (a)] and compared the amount of published data on their relations with ischaemic stroke versus acute coronary events by systematic review of all studies published up to 2003.

RESULTS

From a total of 22,875 abstracts reviewed, 266 eligible studies were identified (167 case-control studies and 99 cohort studies). Two hundred and eleven (79%) studies included coronary events as an outcome for the purpose of a risk factor analysis. In 186 (70%) studies, coronary events were the only outcome that was analysed. Only 73 (27%) studies included stroke or TIA as an outcome event, and only 45 studies (17%) reported risk factor analyses for ischaemic stroke separately. These results were qualitatively consistent across the risk factors studied and the relative lack of data on risk factors for stroke was even greater in prospective cohort studies.

CONCLUSION

Data on novel risk factors for stroke are lacking compared with the equivalent data for acute coronary events, and there are very few data on specific subtypes of ischaemic stroke.

Circulating inflammatory markers and risks of cardiovascular and non-cardiovascular disease

There is current interest in the associations of circulating inflammatory markers (C-reactive protein, fibrinogen, white cell count, albumin, erythrocyte sedimentation rate, the factor VIII:von Willebrand factor complex, the tissue plasminogen activator:plasminogen activator inhibitor type 1 complex, fibrin D-dimer) not only with prognosis in acute coronary syndromes and acute stroke, but also in prediction of cardiovascular events in the general population. Recent meta-analyses of long-term prospective studies have established their associations with coronary heart disease (CHD) events, which may be cause, consequence or coincidence. These markers are also associated in epidemiologic studies of general populations with many cardiovascular risk factors (which may confound their associations with CHD risk), and also with asymptomatic arterial disease (of which they be consequences: 'reverse causality'). The causality of their associations with cardiovascular events is questioned by their lack of specificity for risk of cardiovascular events; and by the lack of association of their functional genotypes with CHD in 'Mendelian randomized trials'. Hence, proof of causality awaits testing in randomized-controlled trials of long-term selective reduction by future agents. Markers are of little additional predictive value to current cardiovascular risk scores, and it is premature to advocate their use in screening for cardiovascular risk prior to careful evaluation of costs, risks, and benefits.

[Is fibrinogen a predictor or a marker of the risk of cardiovascular events?]

Most cardiovascular events result from a thrombotic complication of an atherosclerotic lesion. Inflammation plays a central role in both the pathogenesis of atherosclerosis and the progression of its complications (especially plaque rupture). Fibrinogen, on the one hand a marker of inflammation and on the other a major determinant in thrombosis and haemorrheology, plays a central role in atherosclerosis and its thrombotic complications. The clinical data are in agreement with epidemiological data, and show that increased plasma fibrinogen levels (compared with values in paired controls) are predictive of the risk of cardiovascular events - both primary cardiovascular events in the general population and recurrence in patients. Determining the plasma fibrinogen level in terms of genetic predisposition and environmental factors provides a good example of the interrelationship between genes and the environment. It must be recognised that a minimal increase in the fibrinogen level (within the plasma reference values) is an indicator of a significantly increased risk. This shows why epidemiological data are not useful for determining cardiovascular risk in individual patients in daily clinical practice (with the exception of the very high levels that are infrequently observed).

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.

Low level of tissue plasminogen activator activity in non-diabetic patients with a first myocardial infarction

OBJECTIVE

To explore the role of tissue plasminogen activator (tPA) activity and plasminogen activator inhibitor type 1 (PAI-1) in survivors of a first myocardial infarction (MI). Insulin and proinsulin were analysed as potential risk factors.

DESIGN

Case-control study in northern Sweden.

SUBJECTS

A total of 115 patients under 65 years of age with a first MI were enrolled and recalled for further examination 3 months later. Twenty-seven patients were excluded, 17 with known diabetes and 10 who did not come to the follow-up, giving a final number of 88 patients, 73 men and 15 women. Patients were age- and sex-matched with control subjects drawn from the local cohort in the MONICA population survey 1994.

MAIN OUTCOME MEASURES

We compared MI patients and controls using univariate and multiple regression analyses including odds ratios (OR).

RESULTS

PAI-1 activity, fibrinogen, postload insulin and -proinsulin were significantly higher and tPA activity significantly lower in MI patients in the univariate analysis. In a multiple regression analysis, including also age, sex and cardiovascular risk factors, these parameters were divided in quartiles. The lowest quartile of tPA activity was significantly associated with MI (OR = 19.1; CI 3.0-123) together with the highest quartiles of fibrinogen (OR = 25; CI 5.2-120) but other variables were not.

CONCLUSION

Low tPA activity, i.e. low fibrinolytic activity, characterized nondiabetic subjects after a first MI which is not explained by concomitant disturbances in metabolic and anthropometric variables.

von Willebrand factor and factor VIII as risk factors for arterial and venous thrombosis

Since the early 1990s attempts have been made to elucidate whether high concentrations of von Willebrand factor (VWF) and factor VIII (FVIII) in plasma are associated with an increased risk of thrombosis. Several prospective studies on the role of VWF in arterial thrombosis, mainly coronary heart disease, were performed in healthy individuals and patients with previous cardiovascular disease. Although the majority showed an association between high VWF levels and arterial thrombosis, others failed to confirm such findings. A smaller number of studies have evaluated FVIII, mainly for its association with venous thrombosis. Two prospective observations, together with several case-control studies, provided solid evidence of an association between high FVIII levels and a first or recurrent episode of venous thrombosis. On the whole, high levels of VWF and FVIII in plasma confer a moderately high risk of arterial and venous thrombosis, respectively. These findings have no therapeutic implication, but they should be taken into account in the assessment of the individual risk profile.

Periodontal health improves systemic inflammatory and haemostatic status in subjects with coronary heart disease

OBJECTIVES

A relationship between poor oral health and coronary heart disease (CHD) and systemic inflammatory and haemostatic factors has been recently documented in an Italian population. The present study was performed to assess whether intensive dental care may produce a periodontal improvement along with a change in systemic inflammatory and haemostatic factors.

MATERIAL AND METHODS

The study population consisted of 18 males aged 40-65 years with proven CHD and elevated values of systemic inflammatory and haemostatic factors. A detailed description of their oral status was given by using two different dental indices (clinical periodontal sum score and clinical and radiographic sum score). Blood samples were taken for measurement of the following systemic markers of inflammation [(C-reactive protein (CRP), leucocytes, fibrinogen)] and haemostatic factors [(von Willebrand factor, fibrin D-dimer and oxidized-low density lipoprotein (Ox-LDL)]. All parameters were determined in each subject at baseline, after 4 months as a control and 3 months after an intensive protocol of scaling and root planing. anova for repeated measures was used for the statistical analysis.

RESULTS

No statistical difference was found between values at baseline and at the 4-month-control. All oral indexes showed a significant decrease (p< .01) 3 months after periodontal treatment. All systemic inflammatory indexes decreased but only the decrease in CRP reached statistical significance (p< .05). A significant decrease (p< .01) was also found as regards Ox-LDL among haemostatic factors.

CONCLUSIONS

Preliminary results from the present study suggest an association between poor oral status and CHD, and provide evidence that the improvement of periodontal status may influence the systemic inflammatory and haemostatic situation.

A part le fibrinogène, les facteurs/marqueurs d’hémostase ont-ils aussi une place pour évaluer le risque d’accident cardiovasculaire ischémique ?

Most cardiovascular events result from a thrombotic complication of atherosclerotic lesions. In arterial vessels such as the coronary bed, an interrelationship of haemostatic, coagulation and fibrinolytic factors is implicated. While it can be demonstrated that fibrinogen is a risk factor/marker, the role of other factors is not well established. Under arterial flow conditions, platelets are predominantly involved in the thrombotic reaction. Yet, apart from a large increase in the platelet count, the involvement of platelet parameters in cardiovascular risk is not clearly evident. The lack of definitive platelet markers is at least partly due to the difficulty of studying platelet function ex vivo. Several polymorphisms of platelet glycoproteins carrying a moderate increase in risk have been reported, but only in younger patients. One potentially important factor for coagulation is the fibrin structure, which is dependent on fibrinogen, the rate of thrombin generation, the activity of factor XIII and the interrelationship of the cells concerned, all of which act on its sensitivity to thrombosis. Coagulation factors largely affect the rate of thrombin generation. The activity of the fibrinolytic system (and principally any deficiency) has a role in the cardiovascular risk. General markers of cardiovascular risk such as D-dimers are potentially useful, but they increase with thrombin generation and are decreased by a deficiency in fibrinolysis. Furthermore, possibly because they are not indicative of the fibrin structure, they are poorly correlated with clinical events. The poor significance of the available haemostatic, coagulation and/or fibrinolytic parameters is probably due to their lack of representativeness, since haemostatic, coagulation and fibrinolytic systems are all involved in the thrombotic response (and some in atherogenesis itself). Atherogenesis is a multifactorial process and numerous moderate risk factors act in association. Better predictability of the haemostatic tests would probably result from both the design of more representative tests and the evaluation of multiple parameters, and would lead to the definition of a risk score. Technological advances will make this possible.

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.

Coagulation and inflammatory markers in Alzheimer's and vascular dementia

Alzheimer's disease is classified as a degenerative dementia while vascular dementia is known to be associated with atherothrombosis and classical vascular risk factors. However, over the last decade, there is increasing evidence of the role of haemostatic factors and inflammatory mechanisms in the pathogenesis of Alzheimer's disease. Serum markers of hypercoagulability and markers of inflammation could lead to thrombosis, accelerated atherogenesis and resulting dementia of both Alzheimer's and vascular dementia. In this case control study, we studied these serum markers of coagulation and inflammation in patients suffering from dementia.

Atherothrombotic risk factor clustering in healthy male relatives of male patients with intermittent claudication

OBJECTIVE

Family history is an independent risk factor for premature acute myocardial infarction; in contrast, familial risk for peripheral arterial disease (PAD) has yet to be determined. Elevated levels of hemostatic proteins are consistently predictive for cardiovascular risk in "healthy" subjects, and may cluster with underlying insulin resistance. Atherothrombotic risk factor clustering occurs in first-degree relatives of subjects with coronary artery disease and type 2 diabetes. These may contribute to the enhanced cardiovascular risk in these subjects, and we hypothesised that familial clustering may occur in PAD. The objective of this study was to measure atherothrombotic risk factors in healthy male first-degree relatives of men with intermittent claudication, with emphasis on thrombotic risk.

METHODS

One hundred sixty-five healthy male first-degree relatives were compared with control subjects matched for age, sex, and race (n = 165), free from a personal or family history of premature cardiovascular disease. Primary outcome measures were fibrinogen, von Willebrand factor, factor VII clotting activity (FVII:C), and factor XIII levels. Atherosclerotic risk factors were measured, and subjects were genotyped for common functional polymorphisms (factor VII r353q and fibrinogen B beta-455).

RESULTS

Relatives had higher mean levels of fibrinogen (3.04 vs 2.89 g/L; P = .021), FVII:C (117% vs 104%; P = .000), factor XIII B subunit (1.11 vs 1.01 IU/mL; P = .000), and complex (A 2 B 2 ; 1.18 vs 1.11 IU/mL; P = .021). At multivariate analysis the association between relative status and fibrinogen, FVII:C, and factor XIII B subunit levels were independent of other variables.

CONCLUSIONS

The healthy male relatives of men with PAD have elevated levels of fibrinogen, factor VII, and factor XIII. Our results support the existence of thrombotic risk factor clustering in this population at "high risk."

Interactions between fibrinolysis, lipoproteins and leptin related to a first myocardial infarction

BACKGROUND

The summarized importance of haemostatic and metabolic variables (insulin, lipids including lipoprotein (a) [Lp(a)] and leptin) in predicting first myocardial infarction, as well as possible interactions among these variables, have not been reported.

DESIGN

A prospective case-control study nested within the Northern Sweden Health and Disease Cohort.

METHODS

Sixty-two men diagnosed with a first myocardial infarction were sex- and age-matched with 124 controls. Conditional logistic regression was conducted including established risk factors, plasma levels of plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) mass concentration, von Willebrand factor, insulin, proinsulin, specific insulin, apolipoprotein A-I (apo A-I), Lp(a), and leptin. Interaction analysis was also performed for tPA, apo A-I, Lp(a), leptin and proinsulin.

RESULTS

Smoking, low plasma levels of apo A-I and high plasma levels of cholesterol, Lp(a), tPA, PAI-1, proinsulin and leptin were associated with myocardial infarction in univariate conditional logistic regression analysis. High tPA [odds ratio (OR), 21.3; 95% confidence interval (CI), 2.04-222] and Lp(a) (OR, 7.21; 95% CI, 1.31-39.8) and low apo A-I (OR, 0.15; 95% CI, 0.02-0.93) remained significant risk determinants in multivariate analysis with smoking habits, body mass index, hypertension, cholesterol, and diabetes included as covariates. There were non-significant synergic interactions between high Lp(a) and leptin and tPA, respectively, and between high Lp(a) and low apo A-I.

CONCLUSION

Plasma levels of tPA, Lp(a), and apo A-I are independently associated with subsequent development of a first myocardial infarction in men.

Collaborative meta-analysis of prospective studies of plasma fibrinogen and cardiovascular disease

BACKGROUND

Many long-term studies have reported on associations of plasma fibrinogen concentration with cardiovascular disease, but few have been large enough to provide reliable estimates in different circumstances. Moreover, most published prospective studies have related disease risk only to baseline values of plasma fibrinogen (which can lead to substantial underestimation of any risk relationships) and have corrected only for baseline values of possible confounding factors (which can lead to residual biases).

OBJECTIVES

By appropriate combination of data from individual participants from all relevant prospective studies in a systematic 'meta-analysis', with correction for regression dilution, the Fibrinogen Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age- and sex-specific associations of plasma fibrinogen with coronary heart disease (and, where data are sufficient, with other vascular diseases). It will also help to determine to what extent such associations are independent of possible confounding factors.

METHODS

A central database has been established containing data on plasma fibrinogen, sex and other potential confounding factors, age at baseline fibrinogen measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of fibrinogen and potential confounding factors is being sought to allow study-specific correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available prospective studies of plasma fibrinogen will yield information on more than 10000 incident cardiovascular deaths and events among the approximately 200000 total participants who have been monitored, on average, for about 10 years.

Relationship of the platelet glycoprotein PlA and fibrinogen T/G+1689 polymorphisms with peripheral arterial disease and ischaemic heart disease

INTRODUCTION

Genetic variation in plasma fibrinogen and the platelet receptor GP IIIa locus has been independently associated with increased risks of ischaemic heart disease, but there have been few reports on the relationship with peripheral arterial disease. This study determined the risk of peripheral arterial disease and ischaemic heart disease associated with polymorphisms of fibrinogen T/G(+1689) and platelet glycoprotein Pl(A) genes and the effects of cigarette smoking and fibrinogen.

MATERIALS AND METHODS

In the 5-year follow-up phase of the Edinburgh Artery Study, 939 subjects (60-79 years) had DNA extracted from a venous blood sample. One hundred sixteen subjects were identified as having angina, 87 a myocardial infarction, 104 had intermittent claudication and 663 subjects comprised a healthy group.

RESULTS

Distribution of the fibrinogen genotype was similar across the disease and healthy groups. Logistic regression analyses found no significant association between fibrinogen genotype and ischaemic heart disease and peripheral arterial disease. A lower percentage of claudicants had the Pl(A2) allele (8.3% vs. 15.2%, p=0.025). After adjustment for age and sex, the risk of IC associated with the Pl(A2) was half that of the homozygous Pl(A1) genotype (OR 0.49, 95% CI 0.25, 0.88; p<==0.05). Adjustment for lifetime smoking and fibrinogen levels increased the odds slightly to nonsignificance.

CONCLUSIONS

The Pl(A2) genotype was associated with a decreased risk of developing IC. There was no significant relationship between fibrinogen T/G(+1689) genotype and ischaemic and peripheral heart disease in this older population.

Fibrinogen concentration and risk of ischemic stroke and acute coronary events in 5113 patients with transient ischemic attack and minor ischemic stroke

BACKGROUND AND PURPOSE

Fibrinogen is an independent risk factor for coronary events in population-based studies and in patients with coronary heart disease, but there is uncertainty about prediction of stroke, particularly in secondary prevention.

METHODS

We studied unpublished data from 3 prospective studies of patients with recent transient ischemic attack (TIA) or minor ischemic stroke: the United Kingdom TIA Aspirin (UK-TIA) trial (n=1860); the Dutch TIA trial (n=2960); and the Oxford TIA Study (n=293). By separate and pooled analysis, we used Cox models to determine the relationship between fibrinogen and risk of ischemic stroke and other vascular events during 23,272 patient-years of follow-up and adjusted for other risk factors.

RESULTS

There was no significant heterogeneity in fibrinogen risk associations between studies. Fibrinogen predicted subsequent ischemic stroke, with a pooled hazard ratio (HR) for values above the median of 1.34 (95% CI, 1.13 to 1.60; P=0.001). The association tended to be stronger in patients with nonlacunar (HR=1.42; 95% CI, 1.13 to 1.78; P=0.002) than lacunar syndromes (HR=1.09; 95% CI, 0.80 to 1.49; P=0.58), but was not significantly so (P=0.18). There was no association with hemorrhagic stroke (adjusted HR=1.09; 95% CI, 0.55 to 2.17; P=0.81). Fibrinogen predicted acute coronary events (adjusted HR=1.42; 95% CI, 1.18 to 1.70; P<0.001) and all ischemic vascular events (adjusted HR=1.31; 95% CI, 1.15 to 1.49; P<0.001), but not nonvascular death (adjusted HR=1.24; 95% CI, 0.90 to 1.70; P=0.19).

CONCLUSIONS

In patients with a previous TIA or ischemic stroke, risks of recurrent ischemic stroke and acute coronary events increase linearly with fibrinogen levels, but the relationships are weaker than in some previous population-based studies.

The pathophysiology of cigarette smoking and cardiovascular disease: an update

Cigarette smoking (CS) continues to be a major health hazard, and it contributes significantly to cardiovascular morbidity and mortality. Cigarette smoking impacts all phases of atherosclerosis from endothelial dysfunction to acute clinical events, the latter being largely thrombotic. Both active and passive (environmental) cigarette smoke exposure predispose to cardiovascular events. Whether there is a distinct direct dose-dependent correlation between cigarette smoke exposure and risk is debatable, as some recent experimental clinical studies have shown a non-linear relation to cigarette smoke exposure. The exact toxic components of cigarette smoke and the mechanisms involved in CS-related cardiovascular dysfunction are largely unknown, but CS increases inflammation, thrombosis, and oxidation of low-density lipoprotein cholesterol. Recent experimental and clinical data support the hypothesis that cigarette smoke exposure increases oxidative stress as a potential mechanism for initiating cardiovascular dysfunction.

Role of thrombotic and fibrinolytic factors in acute coronary syndromes

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

Poor oral health is associated with coronary heart disease and elevated systemic inflammatory and haemostatic factors

OBJECTIVES

To assess the relationship between poor oral health and coronary heart disease (CHD) and systemic inflammatory and haemostatic factors in an Italian population.

MATERIAL AND METHODS

The study population consisted of 63 males aged 40-65 years with proven CHD and 50 controls matched for age, geographic area, and socioeconomic status. A detailed description of their oral status was given using four different dental indices (total dental index (TDI), panoramic tomography score, clinical periodontal sum score (CPSS), and clinical and radiographic sum score (CRSS)). Blood samples were taken for measurement of the following CHD risk factors: serum total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and glucose; a series of systemic markers of inflammation (C-reactive protein, leucocytes, fibrinogen, homocysteine) and a series of haemostatic factors (von Willebrand factor, fibrin D-dimer, prothrombinic fragment F1.2, plasminogen activator inhibitor type I (PAI-1), and serum antibodies) against oxidized LDL (anti-Ox-LDL).

RESULTS

Multiple logistic regression adjusted for all risk factors for CHD showed statistically significant relationships (p<0.01) between all dental indices and CHD. Significant relationships (p always <0.01) were found between CPSS and CRSS and leucocyte count. Significant relationships (p always <0.05) were also found between TDI and the von Willebrand factor, and between CPSS and the von Willebrand factor, anti-Ox-LDL, and PAI-1.

CONCLUSIONS

The present study suggests an association between poor oral status and CHD, and provides evidence that inflammatory and haemostatic factors could play an important role in this association.

Genetic variability of von Willebrand factor and risk of coronary heart disease: the Rotterdam Study

The von Willebrand factor (VWF) may be causally associated with coronary heart disease (CHD) or merely be a marker of endothelial damage. The G allele of the -1793 C/G promoter polymorphism in the VWF gene has been associated with higher plasma levels of VWF. To investigate whether VWF has a causal role in CHD, we designed a case-cohort study, including 352 subjects with CHD and a random cohort (n = 736), and prospectively examined the association of the -1793 C/G polymorphism with CHD in subjects with and without advanced atherosclerosis. All subjects were </=75 years of age and participating in the population-based Rotterdam Study. Atherosclerosis was assessed by the ankle-arm index. Among subjects with advanced atherosclerosis, heterozygous and homozygous carriers of the G allele had a 3.5 (1.2-10.2) and 1.5 (0.4-5.7) fold increased risk of CHD respectively, compared with C/C homozygotes. The hazard ratio was 2.6 (1.0-6.8) for carriers of at least one copy of the G allele versus non-carriers. No associations were found in the absence of advanced atherosclerosis. In conclusion, this study suggests that the G allele of the -1793 C/G polymorphism in the VWF gene is associated with an increased risk of CHD, but only in subjects with advanced atherosclerosis.

Selected Haemostatic Factors in Carotid Bifurcation Plaques of Patients Undergoing Carotid Endarterectomy

OBJECTIVE

To determine the concentration of selected haemostatic factors (HFs): thrombin-antithrombin complexes (TAT), antithrombin (AT), tissue plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1) and D-dimers in carotid bifurcation plaques and to compare plaque composition in different subgroups of patients (mainly those with symptomatic and asymptomatic carotid stenosis).

MATERIALS AND METHODS

Thirty-eight consecutive patients (20 symptomatic, 18 asymptomatic) undergoing carotid endarterectomy were enrolled in the study. The concentration of selected HFs in carotid plaques was measured using mainly enzyme immunoassay (ELISA). Simultaneously, the concentration of HFs in plasma was also obtained.

RESULTS

Symptomatic plaques contained significantly more TAT complexes (p=0.03). AT was found only in nine out of 38 carotid plaques and was present mainly in symptomatic carotid plaques (n=8/9)(p<0.006). No significant differences were found between symptomatic and asymptomatic carotid plaques with respect to t-PA, PAI-1 and D-dimers concentration. There was an increased concentration of TAT (p<0.001), t-PA (p<0.02) and D-dimers (p<0.02) in carotid plaques of diabetic patients. Patients with coexisting intermittent claudication had elevated levels of D-dimers in carotid plaques (p<0.02). The only positive correlation was demonstrated between the concentration of AT in plasma and carotid plaques (R=0.76; p=0.02).

CONCLUSIONS

All the evaluated HFs are the components of a carotid plaque. Symptomatic patients have increased concentration of TAT complexes in a carotid plaque. The symptomatic carotid plaque contains AT more frequently, which correlates positively with AT plasma levels. The most marked changes in the carotid plaque haemostatic composition (expressed by elevated levels of TAT, t-PA and D-dimers) have diabetic patients.

Comparison of plasma D-dimer and thrombus precursor protein in patients with operable breast cancer as a potential predictor of lymph node metastasis

Fibrin formation and removal is continuous during the development of malignancy. Plasma D-dimer is indicative of ongoing fibrinolysis, and circulating soluble fibrin polymer [thrombus precursor protein (TpP)] represents thrombogenic activity. We evaluated the relationship between plasma D-dimer and TpP levels with tumor extent and examined the use of these markers as possible predictors of lymph node metastasis in breast cancer. Preoperative plasma levels of D-dimer and TpP were measured in these 120 patients (93 breast cancer, 27 benign breast disease) and 29 healthy controls. Plasma levels of D-dimer in patients with breast cancer were significantly higher than in healthy controls and in those with benign breast disease. Plasma D-dimer levels in patients with breast cancer were found to be significantly increased according to tumor stage. We also observed that plasma levels of D-dimer were higher in patients with lymph node metastasis than in patients without metastasis. In contrast, TpP levels were not significantly different by the tumor stages and lymph node metastasis. In conclusion, increased D-dimer levels in breast cancer may suggest that an ongoing fibrinolysis within breast cancer tissue occurs during tumor progression. Positive D-dimer levels might be useful for identifying metastatic lymph node in patients with operable breast cancer. However, plasma TpP was not found to be a sensitive marker for detecting tumor-associated subclinical coagulopathy.

A functional haplotype in the 5' flanking region of the factor VII gene is associated with an increased risk of coronary heart disease

AIMS

The aim of this study was to investigate associations between coronary heart disease risk and polymorphisms in the coagulation factor (F)VII gene in participants of a large prospective study.

METHODS

One thousand nine hundred and fifty-seven men were genotyped for four FVII polymorphisms, -670A-->C, -402G-->A, a 10 base pair insertion at -323 (0 > 10) in the promoter, and R353Q in the structural gene. Associations among genotypes and estimated haplotypes, plasma FVII levels, and coronary heart disease risk were evaluated, and the function of the promoter polymorphisms was assessed in reporter gene assays.

RESULTS

The -670A-->C and -402G-->A polymorphisms were in complete allelic association. The haplotype containing -670C and -402A (frequency =0.23) was associated with significantly increased plasma FVII coagulant activity and increased risk of an initial coronary event, particularly acute myocardial infarction, which remained after correction for conventional risk factors. In contrast, the -323 insertion and Q353 alleles (frequency =0.11 and 0.10, respectively) were associated with decreased plasma FVII levels, but hazard ratios for coronary events in carriers of these alleles were not significantly different from unity. In transiently transfected hepatoma cells, increased basal expression of the reporter gene was directed by a promoter fragment with rare haplotype -670C/-630G/-402A rather than by a promoter fragment with common haplotype -670A/-630A/-402G; -402A was not responsible for this effect.

CONCLUSIONS

The promoter haplotype, -670C/-630G/402A, was associated with significantly increased plasma FVII coagulant activity, risk of an initial coronary event, particularly acute myocardial infarction, and reporter gene expression.

Beneficial effects of metformin on haemostasis and vascular function in man

Type 2 diabetes is characterised by insulin resistance in association with clustering of atherothrombotic risk factors (dysglycaemia, hyperinsulinaemia, hypertension, raised triglyceride, low HDL cholesterol and increased levels of plasminogen activator inhibitor-1 (PAI-1) and clotting factor VII). There is a 3-5 fold increase in risk of myocardial infarction rising to 10-20 fold in the presence of microalbuminuria and overall around 70-75% of subjects with type 2 diabetes die of cardiovascular disease. However, classical risk factors which associate with insulin resistance do not account for all the increased burden of vascular disease in diabetic subjects. Metformin is a biguanide compound which is antihyperglycaemic, reduces insulin resistance and has cardioprotective effects on lipids, thrombosis and blood flow. Metformin has a weight neutral/weight lowering effect and reduces hypertriglyceridaemia, elevated levels of PAI-1, factor VII and C-reactive protein. In addition recent studies indicate that metformin has direct effects on fibrin structure/function and stabilises platelets, two important components of arterial thrombus. The United Kingdom Prospective Diabetes Study (UKPDS) reported that metformin was associated with a 32% reduction in any diabetes related endpoint (p<0.002), a 39% reduction in myocardial infarction (p<0.01) and a non-significant 29% fall in microvascular complications. The figures for macrovascular complications compare favourably for those described for other cardioprotective agents such as ACE inhibitors and statins. These findings confirm metformin as first line therapy in the management of obese insulin resistant type 2 diabetes and in the prevention of the vascular complications of this common condition.

Role of fibrin D-dimer testing in emergency medicine

OBJECTIVES

Systemic values of the fibrinolytic plasma marker fibrin D-dimer are raised in a variety of acute clinical conditions. D-dimer values can now be rapidly determined and used to aid diagnosis in emergency medicine. However, despite clinical guidelines, inappropriate and unnecessary measurement of D-dimer values is a significant clinical problem. An understanding of the pathophysiological basis and limitations of the value of D-dimer values may help reduce this problem. This review discusses the pathophysiology of the fibrinolytic system. The currently used assays, clinical indications, and limitations of D-dimer measurement are reviewed. Finally, the potential future clinical indications for measurement of D-dimer values in emergency medicine are discussed.

METHODS

Literature on D-dimer was identified from Medline, along with cross referencing from the reference lists of major articles on the subject

RESULTS

and conclusions: Systemic D-dimer values aids diagnosis, and is potentially a prognostic indicator, in a variety of clinical conditions in emergency medicine. However, it has limited specificity in patients with comorbid conditions. Although, currently, there is no standard D-dimer assay, immunoturbidimetric assays are the most suitable for use in emergency medicine

The genetics of atherothrombotic disorders: a clinician's view

The development of coronary artery disease is dependent on the interaction of multiple biochemical pathways that lead to the development of plaque in the arterial wall and ultimately plaque instability, plaque rupture and thrombosis. The latter stages lead to vascular obstruction, tissue death and the final phenotype of myocardial infarction. Hemostasis gene association studies of atherothrombotic disorders have been unrewarding, with largely underpowered studies reporting inconsistent results. Clinical studies such as the Multiple Risk Factor Intervention Trial clearly indicate that clustering of classical risk increases the likelihood of myocardial infarction, and the addition of diabetes mellitus to the risk profile exponentially increases the risk of a vascular event. The development of insulin resistance is considered to be a pivotal event in vascular risk with associated clustering of dysglycemia, hyperinsulinemia, systolic hypertension, raised triglyceride and low high-density lipoprotein cholesterol. Additionally, elevated levels of plasminogen activator inhibitor-1, factor (F)VII, FXII, fibrinogen and tissue plasminogen activator occur with insulin resistance to create an atherothrombotic risk cluster. Heritability studies of insulin resistance and the vascular risk profile demonstrate genetic pleitropy between diabetes and vascular risk, which indicate that common genes have an important role. Increasingly, it is felt that inflammation underpins both diabetes and cardiovascular disease and that the expression of the final phenotype(s) may depend on complex gene-environment interactions with regulatory genes, including those for nuclear transcription factors and RNA-binding proteins. The complexity of coronary artery disease and the risk factor interactions make it unlikely that genetic epidemiology will identify genes involved in these processes without a better understanding of environmental influences.

Hematocrit is associated with carotid atherosclerosis in men but not in women

BACKGROUND

It is known that blood and plasma viscosities are associated with clinical manifestations of atherosclerosis, though evidence is not conclusive particularly in women.

OBJECTIVE

To verify whether hematocrit and blood and plasma viscosities are independently associated with carotid atherosclerosis and whether their measurement can improve the definition of the global coronary heart disease (CHD) risk.

METHOD

Eight hundred and ninety-two participants in a cardiovascular disease prevention campaign were examined with regard to conventional CHD risk factors (age, blood pressure, lipids, glucose, body mass index, waist/hip ratio, cigarette smoking and diabetes), hematocrit and blood and plasma viscosities. According to the degree of carotid atherosclerosis, investigated by echo-Doppler, participants were divided in three groups: those without atherosclerosis, those with a low degree of atherosclerosis and those with a high degree of atherosclerosis.

RESULTS

In men, age, blood pressure, intima-media thickness (IMT), hematocrit (47.4+/-3.7%, 47.8+/-3.7%, 48.4+/-3.7%, P<0.05) and blood viscosity (4.69+/-0.51 cP, 4.77+/-0.55 cP, 4.82+/-0.51 cP, P=0.05) increased with increasing degree of carotid atherosclerosis. In women, age, blood pressure, total cholesterol and low-density lipoprotein-cholesterol, IMT and plasma viscosity (1.42+/-0.12 cP, 1.44+/-0.11 cP, 1.46+/-0.13 cP, P<0.05) increased with increasing carotid score. Analysis of covariance (ANCOVA) showed that after adjusting for hematocrit, blood viscosity was no longer different in the three groups. In discriminant analysis, hematocrit, among the hemorheological variables investigated, was independently associated with carotid score in men (F=3.66, P<0.05). Neither hematocrit nor blood and plasma viscosities were significantly associated with carotid score in women.

CONCLUSION

These findings suggest that in men, both hematocrit and blood viscosity are related to carotid atherosclerosis but hematocrit would appear to have an independent effect over and above that mediated by viscosity.

Smoking raises the risk of total and ischemic strokes in hypertensive men

To examine the relation between cigarette smoking and risk of stroke and coronary heart disease among Japanese, we conducted a 14-year prospective study of 3,626 men aged 40-69, initially free from history of stroke and coronary heart disease. We identified 257 strokes (75 hemorrhagic and 173 ischemic strokes) and 100 coronary heart disease events. When we adjusted for age and other cardiovascular risk factors, a significant excess risk among current smokers of > 20 cigarettes/day vs. never-smokers was found for total stroke (relative risk (RR) = 1.6 (95% confidence interval (CI), 1.1-2.4)). The excess risk of total stroke was particularly evident among hypertensives (RR = 2.3 (1.2-4.4)). The multivariate RR of ischemic stroke was 1.6 (1.0-2.5) for total subjects, and 2.2 (1.0-5.0) among hypertensives. Significant excess risks among current smokers of > 20 cigarettes/day vs. never-smokers were also found for coronary heart disease (RR = 4.6 (1.6-12.9)) and total cardiovascular disease (1.9 (1.3-2.7)). The estimated proportion of the events attributable to current smoking was 30 (95% CI, 11-44)% for total stroke and 34 (5-54)% for coronary heart disease. In conclusion, current smoking of > 20 cigarettes per day increased the risk of both total stroke and ischemic stroke among Japanese middle-aged men, and particularly among middle-aged hypertensive men.

Do plasminogen activator inhibitor (PAI-1) or tissue plasminogen activator PAI-1 complexes predict complications in Type 1 diabetes: the Pittsburgh Epidemiology of Diabetes Complications Study

AIMS

To examine the predictive power of plasminogen activator inhibitor-1 (PAI-1) and the complexes it forms with tissue plasminogen activator (tPA-PAI-1) for the two major Type 1 diabetes (T1D) complications (coronary artery disease (CAD) and overt nephropathy) in the context of standard risk factors.

METHODS

Observational prospective study of 454 participants with childhood onset (< 17 years) T1D, aged 18+ years at baseline. PAI-1 and tPA-PAI-1 were determined using ELISA methodology. Follow-up (6 years) was limited to 382 individuals for CAD and 294 individuals for overt nephropathy, after excluding baseline cases. Total, HDL and LDL-cholesterol, triglycerides, HbA1, blood pressure, body mass index (BMI), waist-hip ratio (WHR), leucocyte count, Beck depression score and fibrinogen were also examined.

RESULTS

The 56 incident cases of CAD had marginally lower PAI-1 and higher tPA-PAI-1 levels compared with those free of CAD. However, marginally higher PAI-1 and significantly higher tPA-PAI-1 (P = 0.04) levels were seen in those who developed nephropathy. After controlling for age, both PAI-1 and tPA-PAI-1 showed significant negative correlations with HDL-cholesterol, and positive correlations with triglycerides, WHR, HbA1 and fibrinogen. tPA-PAI-1 was also positively correlated with total and LDL-cholesterol. In multivariate analyses, neither PAI-1 nor tPA-PAI-1 was an independent predictor of CAD or overt nephropathy.

CONCLUSIONS

These results suggest little association between PAI-1 and later CAD in patients with T1D. However, tPA-PAI-1 complexes may be involved in the pathogenesis of overt nephropathy.

Plasma fibrinogen explains much of the difference in risk of coronary heart disease between France and Northern Ireland. The PRIME study

The incidence of coronary heart disease is higher in Northern Ireland than in France. These differences have not been adequately explained. We have investigated the associations of plasma fibrinogen concentration and factor VII activity with the incidence of coronary heart disease in a prospective cohort study involving 10600 men aged 50-59 living in four regions (Lille, Strasbourg, and Toulouse in France, Belfast in Northern Ireland). Baseline fibrinogen and factor VII were measured in 9489 men free of coronary heart disease at entry (7167 in France and 2322 in Northern Ireland). Over 5 years of follow-up, 161 participants developed myocardial infarction (MI) or coronary death (100 in France and 61 in Belfast) and 151 developed angina pectoris (94 in France and 57 in Belfast). The risk of future coronary events was 1.9 times higher in Belfast than in France (95% confidence interval: 1.5-2.4). Baseline mean levels of fibrinogen were significantly higher in Belfast than in France and they were higher in participants who experienced coronary events compared with those who did not in both countries. The age-adjusted relative risk of coronary heart disease associated with a rise of one standard deviation in fibrinogen level was 1.56 (95% confidence interval: 1.29-1.95, P<0.0001) in the whole cohort. This association remained significant after adjustment for other cardiovascular risk factors (relative risk:1.36; 95% confidence interval: 1.14-1.68; P<0.0001). There was no clear geographical variation in factor VII and no significant association between factor VII levels and the risk of coronary events was observed. Classic risk factors explained 25% of the excess risk of coronary heart disease in Belfast compared with France, while fibrinogen alone accounted for 30%. These findings add to the epidemiological evidence that elevated fibrinogen is a major risk factor for coronary heart disease.

Effect of Lactobacillus plantarum 299v on cardiovascular disease risk factors in smokers

BACKGROUND

The short-chain fatty acids formed in the human colon by the bacterial fermentation of fiber may have an antiinflammatory effect, may reduce insulin production, and may improve lipid metabolism. We previously showed in hypercholesterolemic patients that supplementation with the probiotic bacteria Lactobacillus plantarum 299v significantly lowers concentrations of LDL cholesterol and fibrinogen.

OBJECTIVE

We determined the influence of a functional food product containing L. plantarum 299v on lipid profiles, inflammatory markers, and monocyte function in heavy smokers.

DESIGN

Thirty-six healthy volunteers (18 women and 18 men) aged 35-45 y participated in a controlled, randomized, double-blind trial. The experimental group drank 400 mL/d of a rose-hip drink containing L. plantarum 299v (5 x 10(7) colony-forming units/mL); the control group consumed the same volume of product without bacteria. The experiment lasted 6 wk and entailed no changes in lifestyle.

RESULTS

Significant decreases in systolic blood pressure (P < 0.000), leptin (P < 0.000), and fibrinogen (P < 0.001) were recorded in the experimental group. No such changes were observed in the control group. Decreases in F(2)-isoprostanes (37%) and interleukin 6 (42%) were also noted in the experimental group in comparison with baseline. Monocytes isolated from subjects treated with L. plantarum showed significantly reduced adhesion (P < 0.001) to native and stimulated human umbilical vein endothelial cells.

CONCLUSION

L. plantarum administration leads to a reduction in cardiovascular disease risk factors and could be useful as a protective agent in the primary prevention of atherosclerosis in smokers.

Boron supplementation and activated factor VII in healthy men

OBJECTIVE

The aim of the present study was to determine whether postprandial concentrations of the active component of serine protease coagulation factor VII (VIIa) were lowered by acute boron supplementation in vivo.

DESIGN

An acute, randomized, placebo-controlled, double blind, cross-over study.

SETTING

Free-living population.

SUBJECTS

Fifteen apparently healthy men, aged 45-65 y.

INTERVENTIONS

Subjects visited the centre on two occasions, with the study days separated by a minimum of 2 weeks. Following collection of a fasting blood sample, subjects received either placebo or acute bolus of 11.6 mg boron (given as 102.6 mg sodium tetraborate decahydrate) together with a standard fat-rich meal. Blood samples were obtained at 1, 2, 4 and 6 h after the administration of the test meal, during which time subjects were at liberty to consume deionized water only. Blood samples were assayed for concentrations of insulin, glucose, lipids and boron. Measurement of the concentration of activated factor VIIa and of factor VII antigen, and of the activity of coagulation factors VII, IX and X was also carried out.

RESULTS

Plasma boron concentrations were significantly higher following consumption of the boron supplement compared with placebo (0.124+/-0.02 vs 0.008+/-0.01 mg/l; P< or =0.001). There was no significant effect of acute boron supplementation on plasma insulin and glucose concentration or on blood lipid or coagulation factor profile. Factor VIIa rose significantly following consumption of the high fat meal (1.05+/-0.07 vs 1.26+/-0.07; P< or =0.001), but this increase was not altered by boron supplementation.

CONCLUSIONS

Results from this study suggest that acute boron supplementation (at 11.6 mg boron) does not alter the activity of factor VIIa following consumption of a high-fat meal.

SPONSORSHIP

This work was funded by Borax Europe Ltd.

Elevated hemostatic factor levels as potential risk factors for thrombosis

OBJECTIVES

To review the state of the art relating to elevated hemostatic factor levels as a potential risk factor for thrombosis, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations for the use of specific measurements of hemostatic factor levels in the assessment of thrombotic risk in individual patients.

DATA SOURCES

Review of the medical literature, primarily from the last 10 years.

DATA EXTRACTION AND SYNTHESIS

After an initial assessment of the literature, key points were identified. Experts were assigned to do an in-depth review of the literature and to prepare a summary of their findings and recommendations. A draft manuscript was prepared and circulated to every participant in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia prior to the conference. Each of the key points and associated recommendations was then presented for discussion at the conference. Recommendations were accepted if a consensus of the 27 experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.

CONCLUSIONS

Consensus was reached on 8 recommendations concerning the use of hemostatic factor levels in the assessment of thrombotic risk in individual patients. Detailed discussion of the rationale for each of these recommendations is presented in the article. This is an evolving area of research. While routine use of factor level measurements is not recommended, improvements in assay methodology and further clinical studies may change these recommendations in the future.

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

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

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

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