Activated and total coagulation factor VII, and fibrinogen in coronary artery disease

Factor VII and incidence of myocardial infarction in a Japanese population: The Jichi Medical School Cohort Study

BACKGROUND

The role of factor VII (FVII) as a risk factor in myocardial infarction (MI) has been the subject of numerous studies. However, it remains uncertain whether the FVII levels are associated with development of MI.

METHODS

The subjects were 4142 men and women whose activated FVII (FVIIa) and FVII coagulant (FVIIc) levels were measured in the Jichi Medical School Cohort Study. Subjects were divided into tertiles by FVIIa and FVIIc levels, and Cox's proportional hazard model was used to calculate hazard ratios (HRs) for MI.

RESULTS

The multivariate-adjusted HRs (95% confidential interval [CI]) for FVIIa in men were 0.67 (0.67-1.78) in tertile 2 (T2), and 0.52 (0.17-1.60) in T3. In women, the multivariate-adjusted HRs (95% CI) were 0.18 (0.02-1.60) in T2, and 0.39 (0.07-2.20) in T3. The multivariate-adjusted HRs (95% CI) for FVIIc in men were 0.54 (0.21-1.36) in T2, and 0.20 (0.04-0.91) in T3. In women, the multivariate-adjusted HRs (95% CI) were 0.44 (0.07-2.85) in T2, and 0.35 (0.06-2.22) in T3. We used T1 as a reference for all measures.

CONCLUSION

Our findings revealed a significant association between low FVIIc level and incidence of MI in men. The FVIIa and FVIIc levels were inversely related to increased MI risk, but did not reach statistical significance. Future studies are needed to confirm this association.

How it all starts: Initiation of the clotting cascade

The plasma coagulation system in mammalian blood consists of a cascade of enzyme activation events in which serine proteases activate the proteins (proenzymes and procofactors) in the next step of the cascade via limited proteolysis. The ultimate outcome is the polymerization of fibrin and the activation of platelets, leading to a blood clot. This process is protective, as it prevents excessive blood loss following injury (normal hemostasis). Unfortunately, the blood clotting system can also lead to unwanted blood clots inside blood vessels (pathologic thrombosis), which is a leading cause of disability and death in the developed world. There are two main mechanisms for triggering the blood clotting, termed the tissue factor pathway and the contact pathway. Only one of these pathways (the tissue factor pathway) functions in normal hemostasis. Both pathways, however, are thought to contribute to thrombosis. An emerging concept is that the contact pathway functions in host pathogen defenses. This review focuses on how the initiation phase of the blood clotting cascade is regulated in both pathways, with a discussion of the contributions of these pathways to hemostasis versus thrombosis.

Effects of fibrinogen concentrate administration during severe hemorrhage

BACKGROUND

Fibrinogen concentrate has been shown to improve coagulation in dilutional coagulopathy in experimental studies, but clinical experience is still scarce. The aim of this study was to evaluate laboratory data and the clinical outcome of fibrinogen administration in patients suffering from severe hemorrhage.

MATERIALS AND METHODS

A retrospective study over a 3-year observation period of consecutive patients who received a single dose of fibrinogen concentrate but not recombinant factor VIIa as part of their treatment of severe hemorrhage, defined as >6 U of packed red blood cells (PRBCs).

RESULTS

Thirty-seven patients were included, most of them suffering from severe hemorrhage following open heart surgery (68%). After a median fibrinogen dose of 2 g (range 1-6 g), an absolute increase in the plasma fibrinogen concentration of 0.6 g/l was observed (P<0.001). The activated partial thromboplastin time (APTT) decreased significantly (P<0.001), from 52 to 43 s and the prothrombin time (PT) decreased from 20 to 17 s, respectively. The transfusion requirement for PRBCs decreased from 6 to 3 U (P<0.01) in the 24 h after fibrinogen administration, but fresh-frozen plasma and platelet concentrate transfusions did not change significantly. Eight patients (22%) died in intensive care unit and the pre-operative fibrinogen concentration was not significantly different in these patients.

CONCLUSION

Administration of fibrinogen for severe hemorrhage was associated with an increased fibrinogen concentration and a significant decrease in APTT, PT and the requirement for PRBCs.

Tissue factor-induced thrombin generation in the fasting and postprandial state among elderly survivors of myocardial infarction

INTRODUCTION

Tissue factor (TF)-induced thrombin generation (TG) ex vivo has been suggested to be an important method to assess thrombotic risk. No studies have investigated the impact of postprandial lipemia on TF-induced TG. Since myocardial infarction (MI) is associated with elevated postprandial levels of triglycerides, we hypothesized a differential impact of postprandial lipemia on coagulation activation in MI-patients and healthy controls.

MATERIAL AND METHODS

Elderly survivors of acute MI (n=44) and healthy age-and sex matched controls (n=43) underwent a fat tolerance test (1 gram per kg body weight) to assess coagulation activation during postprandial lipemia.

RESULTS

The incremental area under the curve (AUCi) for serum triglycerides was higher in MI-patients than in healthy age-and sex matched controls (5.64±0.52 mmol/L*h and 3.94±0.39 mmol/L*h, p=0.012) during the postprandial phase. Subsequent endogenous activation of coagulation, assessed by FVIIa and thrombin generation (F1+2), was similar among groups and not related to levels of triglycerides during the postprandial phase. Healthy individuals had a gradual decline in TF-induced thrombin generation ex vivo, assessed by endogenous thrombin potential (ETP) (AUCi=-542.4±71.4 nM*min*h, p<0.001), whereas MI-patients retained their ETP (AUCi=127.4±89.0 nM*min*h, p=0.47) in plasma during the postprandial phase (p for group difference=0.005).

CONCLUSIONS

MI-patients had elevated postprandial lipemia and retained their ability for TF-induced TG in plasma ex vivo in the postprandial phase, whereas the capacity gradually decreased in healthy individuals. Further studies are warranted to reveal underlying mechanism(s) and clinical implications.

Serum levels of vitamin D and haemostatic factors in healthy subjects: the Tromsø study

BACKGROUND

Receptors for vitamin D have been found in various tissues, including the vascular endothelium. The role of vitamin D in the haemostatic process is uncertain, but in vitro studies may indicate a pro-fibrinolytic effect.

METHODS

Two hundred and six subjects (105 males) were included in the study. The relations between indices of calcium metabolism and haemostatic factors [tissue plasminogen activator antigen (tPA Ag), plasminogen activator inhibitor 1 (PAI-1), prothrombin fragment 1+2, activated factor VII and total factor VII coagulant activity] and high-sensitivity C-reactive protein (HS-CRP) were examined.

RESULTS

There were significant and negative correlations between serum 25(OH) vitamin D and PAI-1 and tPA Ag, and between serum 1,25(OH)2 vitamin D and tPA Ag and HS-CRP. In a multiple linear regression model with age, gender, body mass index and smoking status as covariables, only the relation between 25(OH) vitamin D and tPA Ag was significant. There were no significant relations between any of the haemostatic factors tested and serum parathyroid hormone.

CONCLUSION

It appears that the serum level of vitamin D is related to fibrinolytic activity and to the integrity of the vascular endothelium, but the clinical importance of this observation remains to be determined.

The Effects of Three Factor VII Polymorphisms on Factor VII Coagulant Levels in Healthy Singaporean Chinese, Malay and Indian Newborns

Factor VII (FVII) is an independent risk factor for coronary artery disease. Three polymorphisms of the factor VII gene (F7) were studied in a group of healthy newborns comprising 561 Chinese, 398 Malays and 226 Asian Indians from Singapore. The allele frequencies of 3 polymorphisms (R353Q, Promoter 0/10bp Del/Ins and Intron 7) in the FVII gene were ascertained through genotyping by polymerase chain reaction and restriction digestion of amplified fragments. In Chinese the minor allele frequencies are Q: 0.04, Ins: 0.03, R7: 0.44; Malays, Q: 0.06, Ins: 0.10, R7: 0.41; and Indians, Q: 0.25, Ins: 0.23, R7: 0.43. Strong linkage disequilibrium (Delta > 0.7) is observed between the 0/10 bp and the R353Q sites in all ethnic groups. We conclude that: (i) the prevalence of the minor Q and Ins alleles of the R353Q and 0/10 bp polymorphisms are significantly higher in the Indian newborns than the Chinese and Malays; (ii) the Q allele is significantly associated (p = 0.01) with a lower plasma FVII coagulant level in the Indian and Malay neonates; and this polymorphism explains up to 3.8% of the variance in FVII coagulant levels; (iii) there is no significant difference in allele frequencies of the three polymorphisms between neonates with and without family histories of CAD.

Investigation of tissue factor and other hemostatic profiles in experimental hypothyroidism

The influence of thyroid failure on hemostasis has been studied and is still not well understood. These patients have high risk for cardiovascular diseases because of the lipid metabolism and procoagulant agents. But the influence of thyroid failure on hemostasis is controversial. Tissue factor (TF) has an important role in the thromboembolic state. Recent experiments have demonstrated that TF-dependent activation of the coagulation cascade plays an important role in the pathophysiology of intravascular thrombus formation. The purpose of the present study was to investigate the contributions of TF, factor VII:C (FVII:C), factor XII:C (FXII:C), and fibrinogen in experimental hypothyroidism. TF was obtained from the thyroid gland and lung tissue of 10 rats following experimental hypothyroidism induced for 30 d and compared with similar tissue from 10 control rats. Significantly increased TF activities were found in hypothyroid rats. By contrast, FVII:C level was significantly decreased when compared with the control group. In this respect it is interesting to note that a hypercoagulable state due to increased thromboplastic activity may occur. Based on those results, elevated tissue factor activities (TFa) of the patients with low thyroid dysfunction may have another risk factor for cardiovascular diseases.

Levels of serum IL-1beta, IL-2, IL-8 and tumor necrosis factor-alpha in patients with unstable angina pectoris

OBJECTIVES

Inflammation is the most important mechanism of plaque disruption playing an essential role in acute coronary syndromes. It is controversial whether the inflammatory mediators are the cause or the result in the development of plaque rupture. Stimulation of interleukins increases adhesion molecules, fibrinogen and plasminogen activator inhibitors,which cause the activation of inflammation and thrombosis. However, the importance of interleukins in acute coronary syndromes has not been clearly defined. We did not find any article concerning relations between the levels of serum interleukin(IL)-1beta, IL-2, IL -8 and tumor necrosis factor (TNF)-alpha in patients with unstable angina pectoris (UAP). So the aim of this study was to determine the levels of serum I -1b, IL-2, IL-8 and TNF-alpha during the early stage of UAP.

METHODS AND RESULTS

Thirty-seven patients with UAP(12 females and 25 males; mean age, 57.5 +/- 9.7 years) within 6 h of admission and 20 healthy volunteers(eight females and 12 males; mean age, 51.3 +/- 6.3 years) were included in the study. IL-1beta, IL-2, IL-8 and TNF-alpha levels were measured using the enzyme-linked immunosorbent assay method. Patients with acute or chronic inflammation, renal failure or chronic heart failure were excluded from the study. The age, gender and risk factors of the study and control groups were similar. The levels of IL-1beta, IL-8 and TNF-alpha were significantly increased (p < /0.0001, p < /0.001 and p < /0.016, respectively) in patients with UAP. There was no difference of IL-2 levels between the UAP group and controls.

CONCLUSION

We detected high levels of IL-1beta, IL-8 and TNF-alpha in patients with UAP during early phase. We suggest that proinflammatory cytokines (e.g. IL-1beta,IL-8, TNF-alpha) may play an important role in the development of atherosclerosis and its complications.

Acute coronary syndromes: should women receive less antithrombotic medication than men?

A recent meta-analysis of all randomised trials assessing the efficacy and safety of glycoprotein IIb/IIIa agents with acute coronary syndromes showed that there was a significant interaction with sex. Explaining this difference requires an analysis of whether it has any pathophysiological basis, whether antithrombotic medications are indeed less efficacious in women in different clinical situations, and whether there are any specific reasons that may have led to the provocative results of the meta-analysis.

Pressure dependence of human fibrinogen correlated to the conformational ?-helix to ?-sheet transition: An Fourier transform infrared study microspectroscopic study

We used Fourier transform infrared (FTIR) microspectroscopy to investigate pressure-induced conformational changes in secondary structure of fibrinogen (FBG). Solid state FBG was compressed on a KBr pellet (1KBr method) or between two KBr pellets (2KBr method). The peak positions of the original and second-derivative ir spectra of compressed FBG samples prepared by the 1KBr method were similar to FBG sample without pressure. When FBG was prepared by the 2KBr method and pressure was increased up to 400 kg/cm(2), peaks at 1625 (intermolecular beta-sheet) and 1611 (beta-sheet aggregates structure and/or the side-chain absorption of the tyrosine residues) cm(-1) were enhanced. The peaks near 1661 (beta-sheet) and 1652 (alpha-helix) cm(-1) also exhibited a marked change with pressure. A linear correlation was found between the peak intensity ratio of 1611/1652 cm(-1) (r = 0.9879) or 1625/1652 cm(-1) (r = 0.9752) and applied pressure. The curve-fitted compositional changes in secondary structure of FBG also indicate that the composition of the alpha-helix structure (1657-1659 cm(-1)) was gradually reduced with the increase in compression pressure, but the composition of the beta-sheet structure (1681, 1629, and 1609 cm(-1)) gradually increased. This indicates that pressure-induced conformational changes in FBG include not only transformations from alpha-helix to beta-sheet structure, but also unfolding and denaturation of FBG and the formation of aggregates.

Plasma fibrinogen and troponin I in acute coronary syndrome and stable angina

We aimed to determine whether there is a stratification among patients with different stages of coronary artery disease with respect to plasma fibrinogen levels, and to assess diagnostic value of plasma fibrinogen in comparison to troponin I in patients with acute coronary syndrome. Fifty-one consecutive patients presenting to our department with acute coronary syndrome within the last 24 h and 52 patients with stable angina with no episode of unstable disease within the last month were analysed. Forty-nine patients with acute coronary syndrome in which both troponin I and fibrinogen levels were present were further evaluated. Blood was collected on admission for routine laboratory tests. Statistical analysis was done using Student's t-test, Pearson correlation and chi-square test, P<0.05 being considered statistically significant. Plasma fibrinogen levels (g/l) were significantly higher in patients presenting with unstable than with stable angina (3.87+/-1.2 vs. 3.26+/-0.65 P=0.002). We have found significant correlation between fibrinogen and troponin I levels in unstable patients (r=0.43, P=0.0015). In patients with acute coronary syndrome an increased inflammation and cardiac injury seem to coexist and correlate. These results seem to confirm the role of this acute phase protein in the pathophysiology of acute coronary syndrome.

Haemostatic profile in hypothyroidism as potential risk factor for vascular or thrombotic disease

The influence of thyroid failure on haemostasis is controversial, both hypocoagulable and hypercoagulable states have been reported. Since both subclinical and overt hypothyroidism have been associated with atherosclerosis, a hypercoagulable state in addition might represent a risk factor for thromboembolic disease. We investigated various haemostatic variables in 42 women with subclinical hypothyroidism and compared them to 66 euthyroid controls. Prothrombin time, activated partial thromboplastin time, fibrinogen, factor VII activity (FVII:C), factor VII antigen (FVII:Ag), factor VIII activity, von Willebrand factor (vWF), antithrombin III, heparin cofactor II, protein C, protein S, plasminogen, antiplasmin, plasminogen activator inhibitor and tissue plasminogen activator, as well as common lipid variables, were measured. Factor VII:C (P < 0.02) and the ratio FVII:C/FVII:Ag (P < 0.01) were significantly increased in subclinical hypothyroid patients compared to the control group. Both parameters remained higher in hypothyroid patients after exclusion of 18 women on oestrogen replacement therapy. No differences were found between the groups with respect to vWF or the other haemostatic and lipid variables tested. Patients with subclinical hypothyroidism had significantly higher levels of FVII:C. The greater increase in FVII:C compared to that of FVII:Ag, as shown by the increase in their ratio, might reflect the presence of activated FVIIa. This might mean a hypercoagulable state, which could contribute to the increased prevalence of coronary heart disease reported in such patients. A hypercoagulable state might be another argument in favour of thyroxine replacement treatment in subclinical hypothyroidism, especially in patients with additional risk factors for vascular disease.

Activity of factor VIIa and von Willebrand factor in non-insulin-dependent diabetic subjects with coronary artery disease

Atherosclerosis is more extensive and occurs earlier in diabetics compared with the general population. The pathophysiology of atherosclerosis is not fully established. We compared the activity of two blood clotting agents, activated factor VII (VIIa) and von Willebrand factor (vWF), in diabetic and non-diabetic subjects with coronary artery disease. According to clinical features, subjects were placed in one of four groups: Group I, non-insulin-dependent diabetes mellitus (NIDDM) with coronary heart disease (CAD) (n = 16); Group II, NIDDM (n = 15); Group III, CAD with no presence of diabetes (n = 17); and Group IV, healthy volunteers (n = 15). The level of factor VIIa was higher in Group I compared with all other groups, and was significantly higher in Group II compared with Group III and Group IV. Activity of vWF was higher in Group I compared with Group II, Group III and Group IV. There was no statistical difference between Group II and Group III. There was no significant correlation between concentration of blood glucose, total cholesterol or triglyceride, duration of diabetes and either factor VIIa or vWF activity. The results of this study suggest that increased activity of plasma vWF and factor VIIa may be useful markers to identify ischaemic heart disease risk in NIDDM subjects.