Lack of association between haemostatic variables and the presence or the extent of coronary atherosclerosis

Prothrombin fragments in cardiovascular disease

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

Diabetes mellitus as a prothrombotic condition

Diabetes mellitus (DM) is characterized by fasting hyperglycaemia and a high risk of atherothrombotic disorders affecting the coronary, cerebral and peripheral arterial trees. The risk of myocardial infarction (MI) is 3-5 fold higher in Type 2 DM and a DM subject with no history of MI has the same risk as a non-DM subject with a past history of MI. In total around 70% of deaths are vascular with poorer outcomes to both acute events and cardiological interventions. It was proposed that clustering of vascular risk factors (hyperinsulinaemia, dysglycaemia, dyslipidaemia and hypertension) around insulin resistance (IR) accounted for the increase in risk with Type 2 DM. The importance of this became apparent with the recognition that risk clustering occurs in normoglycaemic and impaired glucose tolerance (IGT) subjects with IR, in total around 25% of the population in addition to long-standing Type 1 subjects with renal disease. Evidence indicates that thrombotic risk clustering also occurs in association with IR, suppression of fibrinolysis due to elevated concentrations of the fibrinolytic inhibitor, plasminogen activator inhibitor-1 (PAI-1) is invariable with IR and there is evidence that this is regulated by the effects of triglyceride on the PAI-1 gene promoter. Other studies indicated that prothrombotic risk (coagulation factors VII, XII and fibrinogen) also associates with the IR syndrome. The development of endothelial cell dysfunction with suppression of nitric oxide and prostacyclin synthesis, combined with platelet resistance to the anti-aggregatory effects of these hormones leads to loss of control over platelet activation. In addition, hyperglycaemia and glycation have marked effects on fibrin structure function, generating a clot which has a denser structure, resistant to fibrinolysis. The combination of increased circulating coagulation zymogens, inhibition of fibrinolysis, changes in fibrin structure/function and alterations in platelet reactivity creates a thrombotic risk clustering which underpins the development of cardiovascular disease.

Does hemophilia protect against atherosclerosis? A case-control study

Whether carriers of hemophilia are protected against the development of atherosclerosis is controversial. In a case-control study, the presence of atherosclerosis was assessed and quantified with echo-color Doppler of all explorable arterial districts in 50 carriers of hemophilia and in 50 age-matched control individuals. All participants submitted to echo-color Doppler of carotid and femoral axis, of brachial arteries, and of the abdominal aorta. The presence and grade of atherosclerotic plaques were assessed, as well as the intima-media thickness (IMT). At least one atherosclerotic plaque was found in six cases (12.0%) versus 15 controls (30.0%); referring to the total number of plaques, 30% of them were evaluated in patients affected by decreased coagulation while 70% in subjects with normal levels of FVIII. In all the examined districts, the mean IMT was significantly lower in patients with hemophilia than in controls. Hemophilia protects against asymptomatic atherosclerosis.

Decreased heparin cofactor II activity is associated with impaired endothelial function determined by brachial ultrasonography and predicts cardiovascular events

BACKGROUND

Heparin cofactor II (HCII) could inactivate thrombin after binding to dermatan sulfate at injured arterial walls, and has been shown to be a novel and independent antiatherosclerotic factor. However, the relation between plasma HCII activity and peripheral vascular endothelial function remains unclear.

METHODS

A total of 199 patients (mean age, 63+/-14 years) were enrolled and followed up for a median period of 24 months. Endothelial function was assessed using brachial ultrasonography to determine endothelium dependent flow-mediated vasodilation (FMD). Cox regression analyses were conducted for the 199 subjects, with cardiovascular events being defined as myocardial infarction (MI), percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), ischemic stroke, and peripheral artery revascularization.

RESULTS

A total of 31 patients (16%) had cardiovascular events. Patients with cardiovascular events had significantly lower HCII activity (112+/-34 versus 127+/-34%, p=0.027) and lower antithrombin III (ATIII) activity (82+/-12 versus 88+/-13%, p=0.014) than those without events. By multivariate analysis, age (p=0.012), hsCRP (p=0.020) and HCII activity (p=0.035) were correlated with FMD. Kaplan-Meier analysis was performed and showed plasma HCII (p=0.036) and ATIII activities (p=0.005) were predictors of cardiovascular events. By Cox regression analysis, plasma HCII activity (p=0.026) could be an independent predictor of future cardiovascular events, but not ATIII.

CONCLUSIONS

The present study demonstrates that plasma HCII activity is positively correlated with endothelial vasodilator function. Furthermore, plasma HCII activity could be a predictor of future cardiovascular events in patients with suspected coronary artery disease, suggesting its role in atherosclerosis.

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

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

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

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

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

Hemophilia A, von Willebrand disease, and atherosclerosis of abdominal aorta and leg arteries: factor VIII and von Willebrand factor defects appear to protect abdominal aorta and leg arteries from atherosclerosis

We hypothesized that patients with hemophilia or von Willebrand disease might be protected from atherosclerosis because of their coagulation defect. We studied 40 subjects affected by these two coagulation diseases using echocolor Doppler of the abdominal aorta and leg arteries, and compared the results with those obtained in 40 control patients who were homogenous with study patients in terms of sex, age, and risk factors for atherosclerosis. The probands presented a lower number of plaques than the 40 control subjects in the aorta and in the leg arteries. The most serious hemophilic patients had fewer plaques than controls or than patients with mild hemophilia. Both hemophilia and von Willebrand disease seem to protect against atherosclerosis.

The influence of smoking on von Willebrand factor is already manifest in healthy adolescent females: the Floren-teen (Florence Teenager) Study

The early onset of atherosclerosis and the involvement of physiological biochemical, and environmental factors in its pathogenesis is well documented. Few data are available on the role of risk factors related to hemostasis in the pathogenesis of atherosclerosis in the young and, in particular, little information is available on adolescent populations. In the Study of Preventive Medicine and Education Program (Floren-teen Study), von Willebrand factor, a risk factor for cardiovascular disorder, was studied, together with classical cardiovascular risk factors, in apparently healthy students from two high schools in Florence. Familial and personal history, physical examination, and cardiovascular risk factors were evaluated in 144 students (aged 17-19 years). Blood was withdrawn to assess von Willebrand factor (ELISA) and lipid parameters. Levels of von Willebrand factor were significantly higher (P<0.044) in smokers than in nonsmokers and were correlated with the number of cigarettes per day in the whole group (P=0.01) and in females (P=0.006). In females a positive correlation was observed between von Willebrand factor and high-density lipoprotein cholesterol (P=0.0365). There was no significant correlation between von Willebrand factor and blood pressure or between von Willebrand factor and physical activity. In conclusion, this study shows an association between levels of von Willebrand factor and smoking habits and is the first show that even a brief period of smoking affects levels of von Willebrand factor in healthy adolescent females independently of other risk factors. These results stress the relevance of extending prevention programs to reduce smoking in high school students.

The -323Ins10 polymorphism for factor VII is not associated with coronary atherosclerosis in symptomatic men. The REGRESS study group

Elevated factor VII coagulant activity (FVII:C) has been associated with an increased risk of ischaemic heart disease, particularly for fatal events. Results of studies on the association between FVII:C and atherosclerosis are not consistent. FVII:C levels are influenced by several environmental factors and by genetic factors. One of the genetic factors is the -323Ins10 polymorphism in the promoter region of the factor VII gene, which is strongly related to FVII:C, and thus may be associated with ischaemic heart disease. We studied the association of this polymorphism with the severity and progression of atherosclerosis. In 511 male patients of the Regression Growth Evaluation Statin Study, the genotype for the -323Ins10 polymorphism was determined. The minimum obstruction diameter and the mean segment diameter were determined at baseline and after a 2-year follow-up period, and new lesion formation was assessed as well. Cardiovascular events were recorded. No relationship was observed between the -323Ins10 polymorphism and angiographic measures of disease progression, nor on the risk of new cardiovascular events. The results suggest that there is no association between the -323Ins10 polymorphism for factor VII and the severity or progression of coronary atherosclerosis in male patients with symptomatic coronary artery disease.

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

We determined the plasma levels of prothrombin fragment F1+2, thrombin-antithrombin III complexes (TAT), fibrin monomers (FM), D-dimers (DD) and fibrinogen in 57 patients with angiographically verified graded coronary artery disease (CAD) free of concomitant peripheral atherosclerosis, cerebrovascular disease or diabetes mellitus and a group of 21 apparently healthy controls. Blood was collected from the antecubital vein through atraumatic venipuncture prior to the angiographic procedure. Plasma levels of hemostatic markers were related to the presence and graded severity of CAD. The levels of prothrombin fragment F1+2 (1.74+/-0.11 vs. 1.0+/-0.07 nmol/l, P<0.001), FM (41.6+/-5.5 vs. 7.42+/-3.05 nmol/l, P<0.001), TAT (15.6+/-2.7 vs. 2.96+/-0.32 microg/l, P<0.001) and fibrinogen (3.64+/-1.3 vs. 3.08+/-0.33 g/l, P<0.01) were significantly higher in patients with CAD compared to controls, while there was no difference regarding the fibrinolytic system represented by DD (441.6+/-58.9 vs. 337.4+/-42.05 microg/l, n.s.). Within the CAD group, patients with extensive coronary atherosclerosis (> or =2 vessel disease) had significantly higher values for prothrombin fragment F1+2 (1.89 vs. 1.57 nmol/l, P = 0.04), FM (50.7 vs. 29.8 nmol/l, P = 0.03), and a trend to significance was noted for fibrinogen (3.9 vs. 3.3 g/l, P = 0.07) suggesting that blood coagulability was related to the severity of the disease and that hemostatic markers of thrombin activity represent a useful tool to identify patients with a latent hypercoagulable state with a higher susceptibility to sustain coronary thrombosis.

Systemic and translesional activation of coagulation, fibrinolytic, and inhibitory systems in candidates for coronary angioplasty: basal state and effect of successful dilation

OBJECTIVES

Thrombosis is a major contributor to complications associated with coronary interventions. It is unclear whether patients who have undergone angioplasty are predisposed to thrombus formation because of underlying perturbations in their hemostatic equilibrium.

METHODS

Concentration or activity was measured for 14 plasma proteins involved in the coagulation, fibrinolytic, and inhibitory systems. Baseline systemic measurements were compared between patients undergoing balloon angioplasty (n = 15) and normal subjects (n = 32), with sampling repeated at the end of the procedure. To better assess the local hemostatic environment near the site of dilation, intracoronary arterial samples were also obtained just proximal and distal to the dilated stenosis.

RESULTS

Multiple differences in measured coagulation proteins were found at baseline between the angioplasty candidates and control subjects, including higher mean concentration of plasma fibrinogen (P <.001) and lower high-molecular-weight kininogen concentration (P <.01) and factor XII activity (P <.01). Concentrations of the inhibitory proteins antithrombin III and protein S also differed significantly (P <.001 and P <.01, respectively), with a trend toward lower protein C concentration as well (P <.05). Finally, heightened fibrinolysis was suggested by a marked increase in mean plasma d-dimer concentration in the angioplasty candidates (293 +/- 191 ng/mL vs 116 +/- 31 ng/mL, P <.01), with a more modest increase in tissue plasminogen activator (P <.05) and decrease in alpha2-antiplasmin (P <.001). Importantly, none of the parameters obtained during the procedure differed significantly from samples obtained before and after angioplasty, and no translesional gradients were observed.

CONCLUSIONS

Patients with active ischemic syndromes who are considered candidates for coronary angioplasty demonstrate significant and multiple alterations in their coagulation, inhibitory, and fibrinolytic systems. However, no further changes were observed during coronary dilation, either systemically or locally, after pretreatment with typical doses of heparin and aspirin.

Relationships between protein C, protein S, von Willebrand factor and euglobulin lysis time and cardiovascular risk factors in subjects with and without coronary heart disease

Measures of fibrinolytic and thrombotic function have been examined in 55 subjects with recently identified coronary heart disease, and age and sex matched control subjects. Measurements were particularly directed at factors and processes which could be affected by changes in endothelial function and included the euglobulin lysis time as well as plasma levels of von Willebrand factor (vWF). Plasma levels of protein S and protein C were also measured. Measurements were made before and after a period of 10-min veno-occlusion combined with rhythmic hand exercise. In addition anthropometric, haemodynamic and biochemical measurements (plasma lipids and apolipoproteins, glucose and insulin) were obtained and correlated with the haematological parameters. Protein S and vWF levels were significantly higher, both before and after veno-occlusive exercise, in subjects with CHD than in the asymptomatic controls. Euglobulin lysis times were not significantly different but only shortened on veno-occlusive exercise in those without CHD. Protein S levels were significantly correlated with systolic blood pressure, plasma total cholesterol, plasma triglyceride, plasma phospholipid, plasma fasting glucose and both apolipoprotein A1 and B levels. vWF levels were not significantly related to any of the other variables. Subjects whose pre-exercise euglobulin lysis times exceeded 6 h had significantly higher BMI, plasma total cholesterol, triglyceride, phospholipid, insulin, glucose and apoB concentrations and lower HDL cholesterol than those with lysis in less than 6 h. The findings from this study are consistent with a role for endothelial dysfunction in the production of atherosclerotic vascular disease and may indicate additional, non-haemodynamic, mechanisms for such an association. In addition, the relationship between elevated levels of protein S and CHD does not appear to depend on the demonstrated associations between protein S and a number of other cardiovascular risk factors.

Postprandial hemorrheology and apolipoprotein B metabolism in patients with familial hypertriglyceridemia

Impaired postprandial lipoprotein metabolism has been found to be related to the extent of coronary artery disease. Moreover, since dyslipoproteinemias are associated with impaired hemorrheology, we investigated the effect of postprandial hypertriglyceridemia on hemorrheological parameters before and after triglyceride-lowering therapy. Triglyceride-rich lipoproteins (TRLs) separated by ultracentrifugation (d < 1.006 g/dL) and chylomicrons and chylomicron remnants (quantified by apolipoprotein [apo] B-48 determination) were determined after a fat load in 10 patients with familial hypertriglyceridemia before and after therapy with gemfibrozil (900 mg daily). Lipid and hemorrheological parameters (plasma and whole-blood viscosity [PV and BV], red cell aggregation [RCA], hematocrit, and fibrinogen) were determined at baseline and every hour up to 6 hours postprandially. Fasting total triglycerides and TRL triglycerides significantly decreased with gemfibrozil therapy (P < .01). Total triglycerides postprandially increased from 9.53 +/- 1.72 to 14.47 +/- 2.07 mmol/L (TRL triglycerides by 61%) before therapy (P < .05) and from 4.61 +/- 1.28 to 7.17 +/- 0.99 mmol/L (TRL triglycerides by 57%) after therapy (P < .05). The postprandial TRL apo B increase was reduced with gemfibrozil (from 11.6 +/- 2.8 to 20.7 +/- 5.0 mg/dL with therapy v 19.0 +/- 7.6 to 33.0 +/- 12.5 mg/dL before therapy, P < .05, respectively) with a proportionally greater increase in apo B-48 (119% and 169%, respectively) compared with apo B-100 (64% and 64%, respectively). Fasting RCA was improved with lipid-lowering therapy (P < .05), but PV, BV, RCA, and fibrinogen did not show any statistically significant postprandial changes either before or after lipid-lowering therapy. In summary, we did not find any statistically significant changes in hemorrheological parameters, despite a strong postprandial increase of triglycerides. In particular, these findings were independent of fasting triglyceride levels. We conclude that triglyceride-lowering therapy by gemfibrozil had no substantial beneficial effects with respect to hemorrheology in patients with familial hypertriglyceridemia.

Lipid profile, haemostatic variables and angiographically-defined coronary artery disease: a cross-sectional study in an Irish population

More than 300 risk factors for coronary artery disease (CAD) have been described. There are important geographical and racial differences in both the prevalence of CAD and of potential risk factors. The purpose of this study was to determine the relationship between both the presence and extent of angiographically defined CAD in an Irish population and a spectrum of clinical risk factors, lipid profile and haemostatic variables. On univariate analysis, age, male gender, history of smoking, history of hypertension, total cholesterol, triglycerides, LDL, Cholesterol, the LDL:HDL ratio, apoprotein B-100 and the apoprotein B-100: A-II ratio were associated with the presence of CAD. However, in multivariate analysis only age, male gender, a history of smoking and the apoprotein B-100: A-II ratio remained significantly associated with the presence of CAD. These same risk factors and apoprotein B-100 were significantly associated with the extent of CAD on multivariate analysis. In addition, apoprotein B-100 levels appeared to be associated with disease extent. When all significant variables associated with the presence or extent of CAD were analysed together in a multivariate model, they only accounted for 28% of the variability in the distribution of CAD. Thus, advancing age, male gender, cigarette smoking and apoprotein B-100 appear to be important correlates of the presence and extent of CAD in this selected population. However, in individual patients most of the variability in the distribution of occlusive CAD remains unexplained.

Antithrombin III and fibrinogen as predictors of cardiac events in patients with angina pectoris

Because measurements of hemostatic factors might aid the prediction of cardiovascular clinical events, we investigated the long-term prognostic importance of selected hemostatic factors in patients with angina pectoris. At recruitment, 209 patients underwent clinical assessment and coronary angiography, and a range of hemostatic factors were measured. During the follow-up period of 9 years, 58 patients (28%) suffered a cardiac event (acute myocardial infarction or death from cardiac causes). The risk of cardiac events was positively related to baseline measurements of fibrinogen (risk ratio per SD [RR] increase 1.29, 95% confidence interval [CI] 0.99 to 1.68, P=.06) and negatively related to antithrombin III activity measurements (RR 0.75, 95% CI 0.59 to 0.95, P=.02). No other hemostatic factor measured was significantly related to the risk of having a cardiac event. Worsening of angina in the few weeks before and ejection fraction evaluation at the initial angiography were both strongly related to the risk of cardiac events. However, the relationships of fibrinogen and antithrombin III measurements to risk remained almost unchanged after adjusting for worsening of angina and ejection fraction. Fibrinogen and antithrombin III may have an important etiologic role in the prognosis of patients with angina pectoris.

Protein S and protein C anticoagulant activity in acute and chronic cardiac ischemic syndromes. Relationship to inflammation, complement activation and in vivo thrombin activity

Protein S (PS) and protein C (PC) anticoagulant activities and thrombin-antithrombin complex (TAT) were measured in 20 patients with AIS, 25 patients with chronic stable angina (CSA) and a control group (C). Although plasma levels of TAT were significantly elevated in patients with CSA (p < 0.01 vs C), they were much higher in patients with AIS (p < 0.001 vs CSA). PC anticoagulant activity was similar in patients and controls. At variance, PS anticoagulant activity was lower in patients with AIS than in those with CSA and controls (p < 0.05), reflecting differences in total PS and C4B-binding protein (C4B-BP) antigen possibly resulting from involvement in the mechanisms of inflammation, complement activation and acute-phase response. The ratios of anticoagulant PS and PC to procoagulant vitamin K-dependent factors IX and II were reduced in AIS patients (0.05 > p > 0.005 vs C). In addition, the ratios of anticoagulant PC and PS to factor IX were lower in patients with AIS than in those with CSA (p < 0.05). These results indicate that in patients with acute ischemic cardiac syndromes the markedly increased in vivo thrombin generation is associated with an unbalance between coagulant and anticoagulant vitamin K-dependent factors.

von Willebrand factor, endothelial cell damage and atherosclerosis

von Willebrand factor (vWf) is an interesting and potentially important molecule whose biology in health and disease warrants attention. A growing body of knowledge now suggests that plasma levels of this specific product of the endothelial cell may have potential as a marker for the assessment of endothelial injury in vivo. As its functions include platelet aggregation and mediation of platelet adhesion to the subendothelium, it may also have a role in the pathogenesis of progression of atherosclerosis. In comparison to asymptomatic controls, increased levels of vWf are found in atherosclerotic vascular disease and in the presence of several of its major risk factors (smoking, hypercholesterolaemia, hypertension, obesity and diabetes). High plasma levels of vWf are also associated with the prediction of adverse clinical events such as myocardial infarction and poor outcome following arterial surgery, possibly by the promotion of thrombus formation. These and other studies indicate that research directed towards determining whether therapy to reduce levels of vWf also influences the progression of arterial disease should prove to be profitable.

Severity of peripheral atherosclerosis is associated with fibrinogen and degradation of cross-linked fibrin

Immunohistochemical studies of human atherosclerotic lesions have demonstrated the occurrence of fibrin deposition and its degradation in the arterial wall. We studied fibrinogen, the generation of thrombin, and the degradation of fibrin in 40 patients with stable peripheral arterial occlusive disease of varying severity, as assessed by the ankle/brachial pressure index and duplex ultrasonography and/or angiography. Circulating fibrinogen (functional and immunological), fibrinopeptide A, thrombin-antithrombin III complex, and D-dimer were measured. The severity of atherosclerosis was associated with both fibrinogen (both functional and immunological) and D-dimer (r = .57, P < .0002, and r = .57, P < .0001, respectively). Fibrinogen and D-dimer showed a significant positive correlation (r = .50, P < .001). Generation of thrombin was detected in 24 patients (60%) by fibrinopeptide A and levels of thrombin-antithrombin III complex. As a sign of coagulation activation and fibrinolysis, we found that thrombin-antithrombin III complex and the degradation of cross-linked fibrin were progressively associated with the extent of vascular disease. The plasmin-mediated fibrin breakdown contributed to increased levels of circulating fibrinogen, an established risk factor for thrombotic complications. The significant correlations between fibrinogen/D-dimer and the severity of atherosclerosis support previous pathological studies and imply that local degradation of cross-linked fibrin is involved in the progression of atherosclerosis.

Tissue plasminogen activator, plasminogen activator inhibitor-1 and von Willebrand factor in rheumatoid arthritis

Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF), all of endothelial origin and active in the haemostasis, were analysed in 74 patients with rheumatoid arthritis. The concentrations were related to extra-articular disease and to the incidence of thromboembolic events (TE) registered in a 2-year follow-up period. Patients with extra-articular disease had a significant increase in PAI-1 activity and reduced tPA release in the venous occlusion test. von Willebrand factor, PAI-1 and also haptoglobin and triglycerides were significantly increased in the group of patients who later suffered from TE. In a multiple regression model, in which cholesterol, triglycerides and lipoprotein (a) showed significant association with TE, vWF had the strongest additive explanatory value. No distinct acute phase pattern of PAI-1 was found in any patient subgroup.

Relationship between the extent of coronary artery disease and indicators of free radical activity

Clinical studies have demonstrated that patients with coronary artery disease (CAD) have markers suggestive of increased free radical (FR) activity when compared with normal subjects; however, the relationship between the extent of CAD and level of FR markers is not known. The following indices of FR activity, plasma malondialdehyde (MDA), plasma thiols (PSH), red blood cell (RBC) glutathione (GSH), and RBC superoxide dismutase (SOD) were measured in 58 patients admitted for coronary angiography and in 50 matched controls. Regression analysis demonstrated no significant correlation between MDA, PSH, GSH, or SOD, and the angiographic grade which indicated the severity of the CAD. Patients with angiographically proven CAD (median 7.9 nmol/ml IQR 6.9-9.2) and patients with a history suggestive of angina pectoris but normal coronary angiograms (median 8.4 nmol/ml IQR 7.4-9.9) had significantly raised MDA levels compared with the controls (median 6.85 nmol/ml IQR 6.1-7.4), p less than 0.001 and p less than 0.005, respectively. The patients with angiographically proven CAD had significantly lower GSH levels (median 1461 microM IQR 1348-1709, p less than 0.002) compared with the controls (median 1754 microM IQR 1492-1930). Significantly raised SOD levels also were detected in patients with angiographically proven CAD (median 121.8 U/ml RBC, IQR 113.8-143.9) and in patients with a history of suggestive of angina pectoris but normal coronary angiograms (median 146 U/ml RBC, IQR 96.8-156.7) when compared with controls (median 96.3 U/ml RBC, IQR 82.4-115.6), p less than 0.001 and p less than 0.02, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

von Willebrand factor in plasma: a novel risk factor for recurrent myocardial infarction and death

OBJECTIVE

To evaluate as predictors of reinfarction and mortality tissue plasminogen activator antigen and activity before and after venous occlusion, plasminogen activator inhibitor, von Willebrand factor, and established risk factors.

DESIGN

Prospective study with a mean observation time of 4.9 years.

SETTING

Secondary referral centre, the Department of Internal Medicine, University Hospital of Umeå.

PATIENTS

123 consecutive survivors of myocardial infarction under the age of 70 years.

MAIN OUTCOME MEASURES

Reinfarction and deaths from all causes.

RESULTS

23 patients died and 36 patients had at least one reinfarction. High concentrations of von Willebrand factor were independently associated with both reinfarction and mortality. A history of angina at entry into the study was also independently associated with reinfarction and mortality. Hypertension was independently associated with mortality but not with reinfarction. None of the fibrinolytic or lipid variables was associated with reinfarction or death.

CONCLUSION

A high concentration of von Willebrand factor was a novel index of increased risk for reinfarction and mortality in survivors of myocardial infarction.

Fibrinogen, factor VII clotting activity and coronary artery disease severity

To asses the relationship between fibrinogen, factor VII coagulant (VIIc) activity and extent of coronary artery disease, we studied 43 white males shown to have greater than 50% stenosis of at least one major coronary artery. Thirty six had a definite history of myocardial infarction at least 3 months earlier and were classified as having 1, 2 or 3 vessel disease while 7 had 2 or 3 vessel disease, but no prior infarction. Groups were similar with regard to age, body mass index and blood pressure. In those with documented prior infarction, there was a significant relationship between the extent of atheroma and coagulation variables factor VIIc and fibrinogen. However, given a similar degree of atheroma, patients with prior infarction had significantly higher levels of factor VIIc activity compared with patients without such a history. These results corroborate those from prospective studies confirming a significant role for the coagulation system in the clinical manifestation of coronary artery disease.

Fibrinogen as a major risk factor in cardiovascular disease

Evidence has accumulated over the past ten years to implicate elevated plasma fibrinogen levels in cardiovascular disorders such as ischaemic heart disease, stroke and peripheral vascular disease. At a cellular level, insight has been gained into the molecular regulation of fibrinogen biosynthesis and the mechanisms through which fibrinogen may be involved in these disease processes. Here, Nigel Cook and David Ubben summarize this evidence and consider the possibilities for novel therapies targeted at fibrinogen. A variety of structurally diverse pharmacological agents, many of which were developed for their effects on plasma lipids, have serendipitously been found to lower plasma fibrinogen levels.

Markers of disease severity in peripheral atherosclerosis

Many studies have attempted to define haematological markers of disease severity in patients with coronary artery disease but there are few similar analyses in peripheral arterial disease. We have determined haematological correlates of disease severity in 51 patients with angiographically documented occlusive arterial disease. Transfemoral arteriograms performed within the previous 12 months were visually scored for disease severity using a reproducible method. Fasting venous blood samples were withdrawn on two separate occasions from each patient and a complete lipoprotein and haematological profile obtained. These determinations included total cholesterol and triglycerides, lipoproteins with their respective apoproteins, plasma lipid peroxides, fibrinogen, factors VII and VIII and rheological indices (haematocrit, whole blood and plasma viscosity). Mean values for each parameter were correlated with the angiographic score. Of the significant correlations, total cholesterol, triglycerides, low density lipoprotein and apoprotein B were all significantly inversely related to disease severity, in contrast to plasma lipid peroxides which showed a weak positive correlation (r = 0.27, P = 0.06). The best index of disease severity was the lipid peroxide/total lipid ratio (r = 0.41, P less than 0.005). This data strengthens the hypothesis that lipid peroxides are involved in atherogenesis and also suggests that they are the best available plasma marker of disease severity in patients with peripheral arterial disease.

Disorders of the hemostatic system and the risk of the development of thrombotic and cardiovascular diseases: limitations of laboratory diagnosis

The relationship between hemostatic abnormalities and thrombotic and cardiovascular diseases is summarized. All known congenital and acquired abnormalities in the biochemistry of hemostasis are related to thrombotic and cardiovascular diseases in the way that would be expected on the basis of theories about the role of balances between coagulation and fibrinolysis and between activating and inhibiting factors. Notwithstanding the consistency between theory and observed abnormalities, a causal relationship between biochemical abnormality and clinical symptoms has been proved only in a limited number of situations, and it is possible that certain abnormalities only (or also) mark pathologic events. The limitations of laboratory diagnosis of hemostatic disorders in relation to hemostasis as a local process are discussed. It is proposed that more attention be paid to methods of evaluating the local aspects, for example, methods that assess reaction products in the circulation and that can provide an averaged message of the local phenomena. In addition, such methods can provide information about the dynamic balances in the hemostatic system, whereas historically more attention has been paid to the static balances in the potential of hemostatic processes.

Arterial disease risk factors and angiographic evidence of atheroma of the carotid artery

We conducted a prospective study of serial intravenous digital subtraction angiography to determine the relation of arterial disease risk factors and hemostatic variables with the presence of visible atheroma at the carotid bifurcation. Of the 492 patients with cerebrovascular disease or ischemic heart disease who entered the study, 354 had hematologic studies, including platelet aggregation in 230. Abnormal angiograms were associated with greater age, treated hypertension, current smoking, and lower hemoglobin levels but with higher uric acid, factor VIII, and fibrinogen concentrations. In patients presenting with isolated transient ischemic attacks, abnormal angiograms were also associated with higher levels of cholesterol and triglycerides. To study atheroma progression, the 230 patients with complete data at entry were recalled 2 years later. Repeat angiography in 209 patients showed progression of visible bifurcation disease in 13.4%. There was some evidence that progression was linked to higher age, hypertension, and more severe disease at entry, but further analysis was hampered by the small number of patients showing increased plaque size. The possible role of risk factors and hemostatic variables, especially fibrinogen, is discussed. Factors that did not correlate with progression of angiographically visible disease may also influence clinical end points by other mechanisms, such as thrombogenesis.

Predictive value of factors of the hemostatic system in screening procedures for coronary artery disease

Thromboembolic events play a major pathogenetic role in the final occlusion of atherosclerotic vessels. May such a catastrophic event be predicted or an increased risk be indicated by analyzing the hemostatic system in plasma? A hugh literature exists about disturbances of the platelet, coagulation and fibrinolytic systems after atherosclerotic events such as myocardial infarction or stroke. This data, however, has no predictive significance. In contrast, the epidemiological studies in healthy persons have shown fibrinogen to be a potent risk predictor which is independent from other risk factors such as age, cholesterol or cigarette smoking. Results on factor VII:C are still controversial. Ongoing studies have included further factors of the hemostatic system. A second approach to elaborate the predictive power of hemostatic factors is to follow up patients with overt atherosclerotic disease and to correlate baseline hemostatic tests with event recurrences. The ECAT Angina Pectoris Study performed in 19 European clinical centers will present its prospective results by 1990. Some correlations of risk factors at baseline point to the many interrelationships among each other and to the need of careful statistical management of such data. It is reasonable to include fibrinogen in the recently developed coronary risk scores. So far, thrombin clotting time procedures, such as the Clauss method, appear to be appropriate for the purposes of risk prediction.

Lipid peroxides and atherosclerosis

Plasma lipid peroxide concentrations were measured in 100 patients with occlusive arterial disease proved angiographically (50 patients with ischaemic heart disease, 50 with peripheral arterial disease) and compared with values in 75 control patients with no clinical evidence of atherosclerosis. Lipid peroxide concentrations were significantly higher in patients both with ischaemic heart disease (median 4.37 mumol/l (interquartile range 3.85-5.75 mumol/l); p less than 0.001) and with peripheral arterial disease (median 4.37 mumol/l (3.88-5.21 mumol/l); p less than 0.001) than in controls (median 3.65 mumol/l (interquartile range 3.29-3.89 mumol/l). Overall there was a significant but weak correlation between plasma lipid peroxide and plasma triglyceride concentrations (rs = 0.25; p less than 0.001) but not between plasma lipid peroxide and plasma total cholesterol concentrations. Furthermore, hypertension, obesity, diabetes, smoking, positive family history, and intake of beta blockers and thiazide diuretics were not associated with significant differences in lipid peroxide values. This study provides clinical support to experimental data indicating that peroxidised lipids may be important in atherogenesis and its complications and also suggests that peroxidised lipids may provide an index of the severity of atherosclerosis.