Plasma fibrinogen level and the risk of major cardiovascular diseases and nonvascular mortality: an individual participant meta-analysis

Associations of factor VIIIc, D-dimer, and plasmin-antiplasmin with incident cardiovascular disease and all-cause mortality

To examine the associations of three understudied hemostatic factors--D-dimer, factor VIII(c), and plasmin-antiplasmin (PAP) complex--with incident cardiovascular disease (CVD) and all cause mortality in the Multiethnic Study of Atherosclerosis cohort. Hemostatic factors were measured at baseline in 45-84-year-old patients (n = 6,391) who were free of clinically recognized CVD. Over 4.6 years of follow-up, we identified 307 CVD events, 207 hard coronary heart disease events, and 210 deaths. D-dimer, factor VIII(c), and PAP were not associated with CVD incidence after adjustment for other risk factors. In contrast, each factor was associated positively with total mortality, and D-dimer and factor VIII(c) were associated positively with cancer mortality. When modeled as ordinal variables and adjusted for risk factors, total mortality was greater by 33% (95% CI 15-54) for each quartile increment of D-dimer, 26% (11-44) for factor VIIIc, and 20% (4-38) for PAP. This prospective cohort study did not find D-dimer, factor VIII(c), or PAP to be risk factors for CVD. Instead, elevated levels of these three hemostatic factors were associated independently with increased risk of death. Elevated D-dimer and factor VIII(c) were associated with increased cancer death.

Antihypertensive pharmacogenetic effect of fibrinogen-beta variant -455G>A on cardiovascular disease, end-stage renal disease, and mortality: the GenHAT study

OBJECTIVE

The FGB gene codes for fibrinogen-beta, a polypeptide of the coagulation factor fibrinogen, which is positively associated with cardiovascular diseases. Studies show that angiotensin-converting enzyme (ACE) inhibitors lower plasma fibrinogen concentrations, whereas diuretics and calcium-channel blockers do not. As carriers of the FGB-455 minor 'A' allele have higher levels of fibrinogen while ACE inhibitors lower it, we hypothesize that 'A' allele carriers benefit more from antihypertensive treatment with ACE inhibitors than calcium-channel blockers or diuretics, relative to 'GG' genotype individuals.

METHODS

The Genetics of Hypertension Associated Treatment (GenHAT) study [ancillary to Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)] genotyped hypertensive participants for several hypertension-related candidate genes, making this a post-hoc analysis of a randomized trial. In total, 90.1% of the ALLHAT population was successfully genotyped for FGB-455. We included participants (n=30 076) randomized to one of three antihypertensive medications (lisinopril, amlodipine, chlorthalidone), with two treatment comparisons: lisinopril versus chlorthalidone and lisinopril versus amlodipine. The primary outcome of ALLHAT/GenHAT was coronary heart disease, defined as fatal coronary heart disease or non-fatal myocardial infarction, and secondary outcomes included stroke, heart failure, all-cause mortality, and end-stage renal disease (ESRD) with mean follow-up time of 4.9 years. Genotype-by-treatment interactions (pharmacogenetic effects) were tested with the Cox regression.

RESULTS

Stroke: common 'GG' homozygotes had higher risk on lisinopril versus amlodipine [hazard ratio (HR)=1.38, P<0.001], whereas minor 'A' allele carriers had slightly lower risk (HR=0.96, P=0.76; P value for interaction=0.03). Mortality: 'GG' homozygotes had higher risk on lisinopril versus amlodipine (HR=1.12, P=0.02) or chlorthalidone (1.05, P=0.23), whereas 'A' allele carriers had slightly lower risk (HR=0.92, P=0.33 for lisinopril versus amlodipine; HR=0.88, P=0.08 for lisinopril versus chlorthalidone; P value for interactions 0.04 and 0.03, respectively). ESRD: 'GG' homozygotes had higher risk on lisinopril versus chlorthalidone (HR=1.27, P=0.08), whereas 'A' allele carriers had lower risk (HR=0.64, P=0.12; P value for interaction=0.03).

CONCLUSION

There was evidence of pharmacogenetic effects of FGB-455 on stroke, ESRD, and mortality, suggesting that relative to those homozygous for the common allele, variant allele carriers of the FGB gene at position -455 have a better outcome if randomized to lisinopril than chlorthalidone (for mortality and ESRD) or amlodipine (for mortality and stroke). For the models in which a pharmacogenetic effect was observed, the outcome rates among 'GG' homozygotes were higher in those randomized to lisinopril versus amlodipine or chlorthalidone, whereas minor 'A' allele carriers had lower event rates when randomized to lisinopril versus the other medications.

Hyperfibrinogenemia and functional outcome from acute ischemic stroke

BACKGROUND AND PURPOSE

Epidemiological studies have found strong correlations between elevated plasma fibrinogen levels and both ischemic stroke incidence and stroke mortality. Little is known about the influence of fibrinogen levels on functional stroke outcome.

METHODS

Placebo data from the Stroke Treatment with Ancrod Trial (STAT) and European Stroke Treatment with Ancrod Trial (ESTAT) were analyzed. Fibrinogen levels were determined within 3 hours (STAT) or 6 hours (ESTAT) of stroke onset and at preset intervals throughout 5 days of intravenous infusions. Barthel Index scores at 90 days quantified functional outcomes. The association between initial fibrinogen levels and functional outcomes was evaluated using a multiple logistic regression analysis.

RESULTS

Fibrinogen levels increased gradually over the first 24 hours from a pretreatment median value of 340 mg/dL to a 24-hour median value of 376 mg/dL. In a univariate analysis, the proportion of patients with good functional outcome decreased with increasing quartiles of initial fibrinogen levels in both STAT (36.0% to 26.2%) and ESTAT (53.8% to 24.8%). In a multifactorial analysis, the same trend was observed. Patients with initial fibrinogen levels <450 mg/dL had better outcomes in both studies; the difference (42.0% versus 21.6%) was significant in ESTAT (P=0.0006), even when corrected for age and initial stroke severity.

CONCLUSIONS

The independent association of higher initial fibrinogen levels with poor outcome needs to be verified using a larger acute stroke dataset. Even in the present small populations, the apparent association of these 2 variables suggests that treatments designed to reduce fibrinogen levels could potentially be important in treating acute ischemic stroke.

Systematically missing confounders in individual participant data meta-analysis of observational cohort studies

One difficulty in performing meta-analyses of observational cohort studies is that the availability of confounders may vary between cohorts, so that some cohorts provide fully adjusted analyses while others only provide partially adjusted analyses. Commonly, analyses of the association between an exposure and disease either are restricted to cohorts with full confounder information, or use all cohorts but do not fully adjust for confounding. We propose using a bivariate random-effects meta-analysis model to use information from all available cohorts while still adjusting for all the potential confounders. Our method uses both the fully adjusted and the partially adjusted estimated effects in the cohorts with full confounder information, together with an estimate of their within-cohort correlation. The method is applied to estimate the association between fibrinogen level and coronary heart disease incidence using data from 154,012 participants in 31 cohorts

Do inflammatory biomarkers add to the discrimination of cardiovascular disease after allowing for social deprivation? Results from a 10-year cohort study in Glasgow, Scotland

AIMS

To assess the additional discriminative value of adding each of five inflammatory biomarkers to the ASSIGN risk score, which includes social deprivation.

METHODS AND RESULTS

In this study, 1319 men and women aged 25-64 in the fourth Glasgow MONICA study were followed-up for cardiovascular endpoints. Baseline C-reactive protein, fibrinogen, IL-6, IL-18, and TNFα were related to risk of CVD. The discriminative value of adding each to the ASSIGN score was assessed using area under the receiver operating characteristic (AUC) and relative integrated percentage improvement in classification (RIDI). During a median of 10.5 years, 151 CVD events occurred. After adjusting for ASSIGN variables, each inflammatory marker except IL-18 had a significant (P < 0.05) association with CVD risk. The AUC using ASSIGN [0.799 (95% CI 0.790-0.809)] was improved by the inclusion of C-reactive protein and TNFα [0.805 (95% CI 0.795-0.815); P < 0.03], but not by other combinations. C-reactive protein and TNFα yielded a significant RIDI (IL-6 almost so). C-reactive protein and TNFα together improved the classification of risk by 11% (95% CI, 3-19%) when added to the ASSIGN variables.

CONCLUSION

Some inflammatory biomarkers add moderate discriminative information to the ASSIGN CVD risk score. The clinical utility of this information, cost-effectiveness, and optimization should be assessed in future studies.

Fibrinogen Studies Collaboration. Correcting for multivariate measurement error by regression calibration in meta-analyses of epidemiological studies

Within-person variability in measured values of multiple risk factors can bias their associations with disease. The multivariate regression calibration (RC) approach can correct for such measurement error and has been applied to studies in which true values or independent repeat measurements of the risk factors are observed on a subsample. We extend the multivariate RC techniques to a meta-analysis framework where multiple studies provide independent repeat measurements and information on disease outcome. We consider the cases where some or all studies have repeat measurements, and compare study-specific, averaged and empirical Bayes estimates of RC parameters. Additionally, we allow for binary covariates (e.g. smoking status) and for uncertainty and time trends in the measurement error corrections. Our methods are illustrated using a subset of individual participant data from prospective long-term studies in the Fibrinogen Studies Collaboration to assess the relationship between usual levels of plasma fibrinogen and the risk of coronary heart disease, allowing for measurement error in plasma fibrinogen and several confounders.

Autonomic function and prothrombotic activity in women after an acute coronary event

BACKGROUND

The link between decreased heart rate variability (HRV) and atherosclerosis progression is elusive. We hypothesized that reduced HRV relates to increased levels of prothrombotic factors previously shown to predict coronary risk.

METHODS

We studied 257 women (aged 56 +/- 7 years) between 3 and 6 months after an acute coronary event and obtained very low frequency (VLF), low frequency (LF), and high frequency (HF) power, and LF/HF ratio from 24-hour ambulatory ECG recordings. Plasma levels of activated clotting factor VII (FVIIa), fibrinogen, von Willebrand factor antigen (VWF:Ag), and plasminogen activator inhibitor-1 (PAI-1) activity were determined, and their levels were aggregated into a standardized composite index of prothrombotic activity.

RESULTS

In bivariate analyses, all HRV indices were inversely correlated with the prothrombotic index explaining between 6% and 14% of the variance (p < 0.001). After controlling for sociodemographic factors, index event, menopausal status, cardiac medication, lifestyle factors, self-rated health, metabolic variables, and heart rate, VLF power, LF power, and HF power explained 2%, 5%, and 3%, respectively, of the variance in the prothrombotic index (p < 0.012). There were also independent relationships between VLF power and PAI-1 activity, between LF power and fibrinogen, VWF:Ag, and PAI-1 activity, between HF power and FVIIa and fibrinogen, and between the LF/HF power ratio and PAI-1 activity, explaining between 2% and 3% of the respective variances (p < 0.05).

CONCLUSIONS

Decreased HRV was associated with prothrombotic changes partially independent of covariates. Alteration in autonomic function might contribute to prothrombotic activity in women with coronary artery disease (CAD).

Novel loci, including those related to Crohn disease, psoriasis, and inflammation, identified in a genome-wide association study of fibrinogen in 17 686 women: the Women's Genome Health Study

BACKGROUND

Fibrinogen is a multifunctional circulating glycoprotein involved in wound healing, thrombosis, platelet aggregation, and inflammation, and elevated levels predict vascular disease. Despite evidence of crucial biological function and moderate heritability, comprehensive analysis of the influence of genetic variation on fibrinogen is not available.

METHODS AND RESULTS

To address this issue, we undertook a genome-wide association study evaluating the potential relationships between 337 343 single-nucleotide polymorphisms (SNPs) and plasma fibrinogen levels among 17 686 apparently healthy women participating in the Women's Genome Health Study. As C-reactive protein is also an inflammatory marker known to predict cardiovascular diseases, we compared the determinants of fibrinogen levels with those of C-reactive protein. Four novel loci were identified, in addition to the fibrinogen gene cluster, which were associated with fibrinogen levels at genome-wide levels of significance (range of probability values from 8.82 x 10(-09) to 8.04 x 10(-39)). Two of the loci are related to common chronic inflammatory diseases: the first, at locus 5q31.1 (SLC22A5, SLC22A4, IRF1), lies immediately adjacent to a locus linked to Crohn disease (P value for lead SNP, 1.24 x 10(-12)) and the second, at locus 17q25.1 (CD300LF, SLC9A3R1, NAT9), has been associated with psoriasis (P value for lead SNP, 7.72 x 10(-11)). A third locus at 1q21.3 (IL6R) lies within the interleukin 6 receptor gene, a critical component of the inflammatory cascade (P value for lead SNP, 1.80 x 10(-11)). A novel locus at 2q34 (CPSI) participates in the urea cycle (P=8.82 x 10(-09)). The majority of implicated SNPs showed little evidence of dual association with C-reactive protein levels.

CONCLUSIONS

A genome-wide survey of the human genome identifies novel loci related to common chronic inflammatory diseases as genetic determinants of fibrinogen levels, in addition to loci that relate to the inflammatory cascade, the urea cycle, and the fibrinogen gene cluster.

Elevated fibrinogen levels and subsequent subclinical atherosclerosis: the CARDIA Study

OBJECTIVE

To determine whether elevated levels of hemostatic factors are associated with the subsequent development of subclinical cardiovascular disease.

METHODS

Fibrinogen, factors VII (FVII) and VIII (FVIII), and von Willebrand factor (vWF) were measured in 1396 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Coronary artery calcification (CAC) and carotid intimal/medial thickness (CIMT) were determined 13 years later. The adjusted prevalence of CAC and mean CIMT across the quartiles of each hemostatic factor was computed for the total sample and for each race and gender group.

RESULTS

The age-, race-, and gender-adjusted prevalences of CAC with increasing quartiles of fibrinogen were 14.4%, 15.2%, 20.0%, and 29.1% (p<0.001 for trend). This trend persisted after further adjustment for body mass index (BMI), smoking, educational level, center, systolic blood pressure (BP), diabetes, antihypertensive medication use, total and high-density lipoprotein (HDL) cholesterol, and CRP. A similar trend was observed for CIMT (age-, race- and gender-adjusted, p<0.001; multivariable-adjusted, p=0.014). Further analyses of race and gender subgroups showed that increasing quartiles of fibrinogen were associated with CAC and CIMT in all subgroups except black men. The prevalence of CAC was not associated with increasing quartiles of FVII, FVIII, or vWF, suggesting they may be less involved in plaque progression.

CONCLUSION

An elevated fibrinogen concentration in persons aged 25-37 is independently associated with subclinical cardiovascular disease in the subsequent decade.

Ethnicity and peripheral artery disease

Peripheral arterial disease (PAD) is an important healthcare problem and is an indicator of widespread atherosclerosis in other vascular territories, such as the cerebral and coronary circulations. PAD is associated with considerable morbidity and mortality. Most population-based studies investigating PAD prevalence and risk factors for its development and progression have been based on predominantly White ethnic groups. Much less is known about the characteristics of this disease in other ethnic groups. Understanding the epidemiology of PAD amongst ethnic minority groups is relevant, given that the population of minority ethnic groups in countries such as the United Kingdom rose by 53% between 1991 and 2001 and is expected to rise further in the future. This article aims to provide an overview of possible pathophysiological differences between ethnic groups for PAD, focussing predominantly on South Asians (people originating from India, Bangladesh and Pakistan) and Blacks (people of Black Caribbean and Black African descent) as these groups comprise the majority of all ethnic minorities in the United Kingdom.

Biomarkers of atherosclerosis: clinical applications

Current cardiovascular risk prediction models incorporate traditional risk factors to estimate 10-year cardiovascular risk. Numerous blood-based biomarkers have been identified that are associated with increased cardiovascular risk after adjusting for traditional risk factors. Many of these biomarkers, alone or in combination, have been incorporated into risk prediction models to determine whether their addition increases the model's predictive ability. We review the recently published literature on blood-based biomarkers and examine whether incorporating these markers may improve clinical decision making.

Inflammation and hemostasis biomarkers for predicting stroke in postmenopausal women: the Women's Health Initiative Observational Study

BACKGROUND

Inflammatory and hemostasis-related biomarkers may identify women at risk of stroke.

METHODS

Hormones and Biomarkers Predicting Stroke is a study of ischemic stroke among postmenopausal women participating in the Women's Health Initiative observational study (n = 972 case-control pairs). A Biomarker Risk Score (BRS) was derived from levels of 7 inflammatory and hemostasis-related biomarkers that appeared individually to predict risk of ischemic stroke: C-reactive protein (CRP), interleukin-6, tissue plasminogen activator, D-dimer, white blood cell count, neopterin, and homocysteine. The c index was used to evaluate discrimination.

RESULTS

Of all the individual biomarkers examined, CRP emerged as the only independent single predictor of ischemic stroke (adjusted odds ratio comparing Quartile(4)v Quartile(1) = 1.64, 95% confidence interval: 1.15-2.32, P = .01) after adjustment for other biomarkers and standard stroke risk factors. The BRS identified a gradient of increasing stroke risk with a greater number of elevated inflammatory/hemostasis biomarkers, and improved the c index significantly compared with standard stroke risk factors (P = .02). Among the subset of individuals who met current criteria for high-risk levels of CRP (>3.0 mg/L), the BRS defined an approximately 2-fold gradient of risk. We found no evidence for a relationship between stroke and levels of E-selectin, fibrinogen, tumor necrosis factor-alpha, vascular cell adhesion molecule-1, prothrombin fragment 1+2, Factor VIIC, or plasminogen activator inhibitor-1 antigen (P > .15).

DISCUSSION

The findings support the further exploration of multiple biomarker panels to develop approaches for stratifying an individual's risk of stroke.

Endothelial activation markers in anemic non-dialysis chronic kidney disease patients

BACKGROUND/AIMS

Anemia in chronic kidney disease is an independent predictor of cardiovascular disease (CVD). We explored the relationship between anemia and markers of inflammation and endothelial activation in non-dialysis chronic kidney disease (ND-CKD) patients to understand this mechanism.

METHODS

Cross-sectional analysis was performed on 30 adult ND-CKD patients for markers of inflammation and endothelial activation using a multiplexed immunoassay. Data were analyzed according to the anemic status defined by the modified World Health Organization criteria.

RESULTS

Seventeen patients were classified as anemic. Baseline characteristics by anemic status were similar except that anemic patients were older (p = 0.006), had lower estimated glomerular filtration rate (eGFR; p = 0.01) and higher prevalence of CVD (p = 0.02). Compared to non-anemic patients, log-transformed values of fibrinogen (p = 0.012); von Willebrand factor (vWF, p = 0.008), vascular cell adhesion molecule-1 (VCAM-1, p = 0.025) and C-reactive protein (p = 0.043) were elevated in anemic patients. Serum ferritin (p = 0.93) and serum albumin (p = 0.06) were not different. Age and eGFR-adjusted logistic regression analysis showed that anemic patients had increased odds for a composite of higher median values of fibrinogen, vWF and VCAM-1 (p = 0.01, odds ratio 8.1, 95% CI 1.08-111.0).

CONCLUSION

We report the association of anemia with elevated markers of endothelial activation in ND-CKD patients. Longitudinal studies are needed to confirm our findings.

The relationship between proteinuria and coronary risk: a systematic review and meta-analysis

BACKGROUND

Markers of kidney dysfunction such as proteinuria or albuminuria have been reported to be associated with coronary heart disease, but the consistency and strength of any such relationship has not been clearly defined. This lack of clarity has led to great uncertainty as to how proteinuria should be treated in the assessment and management of cardiovascular risk. We therefore undertook a systematic review of published cohort studies aiming to provide a reliable estimate of the strength of association between proteinuria and coronary heart disease.

METHODS AND FINDINGS

A meta-analysis of cohort studies was conducted to obtain a summary estimate of the association between measures of proteinuria and coronary risk. MEDLINE and EMBASE were searched for studies reporting an age- or multivariate-adjusted estimate and standard error of the association between proteinuria and coronary heart disease. Studies were excluded if the majority of the study population had known glomerular disease or were the recipients of renal transplants. Two independent researchers extracted the estimates of association between proteinuria (total urinary protein >300 mg/d), microalbuminuria (urinary albumin 30-300 mg/d), macroalbuminuria (urinary albumin >300 mg/d), and risk of coronary disease from individual studies. These estimates were combined using a random-effects model. Sensitivity analyses were conducted to examine possible sources of heterogeneity in effect size. A total of 26 cohort studies were identified involving 169,949 individuals and 7,117 coronary events (27% fatal). The presence of proteinuria was associated with an approximate 50% increase in coronary risk (risk ratio 1.47, 95% confidence interval [CI] 1.23-1.74) after adjustment for known risk factors. For albuminuria, there was evidence of a dose-response relationship: individuals with microalbuminuria were at 50% greater risk of coronary heart disease (risk ratio 1.47, 95% CI 1.30-1.66) than those without; in those with macroalbuminuria the risk was more than doubled (risk ratio 2.17, 1.87-2.52). Sensitivity analysis indicated no important differences in prespecified subgroups.

CONCLUSION

These data confirm a strong and continuous association between proteinuria and subsequent risk of coronary heart disease, and suggest that proteinuria should be incorporated into the assessment of an individual's cardiovascular risk.

Serum matrix metalloproteinase-9 and coronary heart disease: a prospective study in middle-aged men

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) has a potential role in arterial plaque rupture, but its relation to risk of coronary heart disease (CHD) is uncertain.

AIM

To determine whether circulating levels of serum MMP-9 are prospectively related to the risk of CHD in the general population.

METHODS

We measured baseline MMP-9 levels in stored serum samples of subjects in a case-control study nested within a prospective study of 5661 men followed up for 16 years for CHD events (465 cases, 1076 controls).

RESULTS

MMP-9 values were associated with cigarette smoking, and with several inflammatory and haemostatic markers, but not with age, body mass index, blood pressure or lipid measurements. Men in the top third of baseline MMP-9 levels had an age-adjusted odds ratio (OR) for CHD of 1.37 (95% CI 1.04-1.82) compared with those in the bottom third. Adjustment for conventional risk factors (smoking in particular) reduced the odds ratio to borderline significance: OR 1.28 (95% CI 0.95-1.74), while additional adjustment for two markers of generalized inflammation, interleukin-6 and C-reactive protein, further attenuated the association: OR 1.13 (0.82-1.56).

CONCLUSION

Serum MMP-9 has a modest association with incident CHD in the general population, which is not independent of cigarette smoking exposure and circulating markers of generalized inflammation. MMP-9 is unlikely to be a clinically useful biomarker of CHD risk, but may still play a role in the pathogenesis of CHD.

Linkage study of fibrinogen levels: the Strong Heart Family Study

Background

The pathogenesis of atherosclerosis involves both hemostatic and inflammatory mechanisms. Fibrinogen is associated with both risk of thrombosis and inflammation. A recent meta-analysis showed that risk of coronary heart disease may increase 1.8 fold for 1 g/L of increased fibrinogen, independent of traditional risk factors. It is known that fibrinogen levels may be influenced by demographic, environmental and genetic factors. Epidemiologic and candidate gene studies are available; but few genome-wide linkage studies have been conducted, particularly in minority populations. The Strong Heart Study has demonstrated an increased incidence of cardiovascular disease in the American Indian population, and therefore represents an important source for genetic-epidemiological investigations.

Methods

The Strong Heart Family Study enrolled over 3,600 American Indian participants in large, multi-generational families, ascertained from an ongoing population-based study in the same communities. Fibrinogen was determined using standard technique in a central laboratory and extensive additional phenotypic measures were obtained. Participants were genotyped for 382 short tandem repeat markers distributed throughout the genome; and results were analyzed using a variance decomposition method, as implemented in the SOLAR 2.0 program.

Results

Data from 3535 participants were included and after step-wise, linear regression analysis, two models were selected for investigation. Basic demographic adjustments constituted model 1, while model 2 considered waist circumference, diabetes mellitus and postmenopausal status as additional covariates. Five LOD scores between 1.82 and 3.02 were identified, with the maximally adjusted model showing the highest score on chromosome 7 at 28 cM. Genes for two key components of the inflammatory response, i.e. interleukin-6 and "signal transducer and activator of transcription 3" (STAT3), were identified within 2 and 8 Mb of this 1 LOD drop interval respectively. A LOD score of 1.82 on chromosome 17 between 68 and 93 cM is supported by reports from two other populations with LOD scores of 1.4 and 1.95.

Conclusion

In a minority population with a high prevalence of cardiovascular disease, strong evidence for a novel genetic determinant of fibrinogen levels is found on chromosome 7 at 28 cM. Four other loci, some of which have been suggested by previous studies, were also identified.

Hemostatic and inflammatory risk factors for intracerebral hemorrhage in a pooled cohort

BACKGROUND AND PURPOSE

The purpose of this study was to identify novel risk factors for intracerebral hemorrhagic stroke (ICH).

METHODS

Risk factors were assessed at baseline in a pooled cohort of the Atherosclerosis Risk in Communities Study (ARIC) and the Cardiovascular Health Study (CHS) involving 21,680 adults aged 45 or over. Over 263,489 person-years of follow-up, we identified 135 incident ICH events.

RESULTS

In multivariable models, for each SD higher baseline level of fibrinogen, the relative rate of incident ICH increased 35% (95% CI, 17% to 55%). Fibrinogen was more strongly related to ICH in ARIC than in CHS. In multivariable models, those with von Willebrand factor levels above the median were 1.72 (95% CI, 0.97 to 3.03) times more likely to have an incident ICH as those below the median. Factor VIII was significantly positively related to ICH in ARIC (relative rate per standard deviation of 1.31; 95% CI, 1.07 to 1.62), but not in CHS. There was no relation in multivariable models between lipoprotein (a), Factor VII, white blood cell count, or C-reactive protein and ICH.

CONCLUSIONS

Greater plasma fibrinogen and, to some degree, von Willebrand factor were associated with increased rates of ICH in these prospective studies, whereas Factor VIII was related to ICH in younger ARIC study participants only.

Vascular risk factors in South Asians

South Asians originate from the Indian sub-continent (India, Pakistan, Bangladesh, Sri Lanka and Nepal) and represent one fifth of the world's population. Several studies suggested that South Asians have an increased risk of developing coronary heart disease (CHD) when compared with European populations. We review the role of traditional and emerging risk factors in the increased CHD risk in South Asians. The high prevalence of insulin resistance and type 2 diabetes mellitus in South Asians may be a major cause for their elevated vascular risk. However, other established and emerging risk factors are also overrepresented in South Asians. Large-scale prospective studies could determine the relative contribution of established and emerging vascular risk factors in South Asians. There is an urgent need for trials in South Asians that will evaluate clinical outcomes following treatment of these risk factors.

Arterial stiffness and inflammatory response to psychophysiological stress

The processes through which psychological stress influences cardiovascular disease are poorly understood, but may involve activation of hemodynamic, neuroendocrine and inflammatory responses. We assessed the relationship between carotid arterial stiffness and inflammatory responses to acute psychophysiologic stress. Participants were 155 healthy men and women aged 55.3, SD 2.7 years. Blood samples for the assessment of plasma fibrinogen, tumor necrosis factor (TNF) alpha and interleukin (IL) 6 were drawn at baseline, immediately following standardized behavioral tasks, and 45 min later. Carotid artery stiffness was measured ultrasonically three years later, and blood pressure and heart rate responses were recorded. The tasks induced substantial increases in blood pressure and heart rate, together with increased fibrinogen, TNFalpha and IL-6 concentration. Carotid stiffness was positively associated with body mass, waist/hip ratio, blood pressure, low density lipoprotein cholesterol, and C-reactive protein, and inversely with high density lipoprotein and grade of employment. Baseline levels of inflammatory variables were not related to carotid artery stiffness. But carotid stiffness was greater in participants with larger fibrinogen (p=0.037) and TNFalpha (p=0.036) responses to psychophysiological stress. These effects were independent of age, gender, grade of employment, smoking, body mass, waist/hip ratio, systolic and diastolic pressure, high and low density lipoprotein cholesterol, and C-reactive protein. There were no associations between carotid stiffness and stress responses in IL-6, blood pressure, or heart rate. We conclude that individual differences in inflammatory responses to psychophysiological stress are independently related to structural changes in artery walls that reflect increased cardiovascular disease risk.

Inflammation-sensitive plasma proteins are associated with increased incidence of heart failure: a population-based cohort study

BACKGROUND

Although inflammation has been associated with different cardiovascular diseases, the relationships with future heart failure (HF) are unclear. This population-based study explored whether elevated plasma levels of inflammatory proteins are associated with incidence of HF.

METHODS

Five inflammation-sensitive plasma proteins (ISPs, fibrinogen, ceruloplasmin, haptoglobin, orosomucoid, and alpha1-antitrypsin) was measured in 6071 men (mean age 46 years) without history of myocardial infarction (MI) or stroke. Incidence of hospitalizations due to HF (primary diagnosis) was monitored over 22 years of follow-up, in relation to the number of elevated ISPs (i.e., in the 4th quartile). Subjects with myocardial infarction during follow-up were censored.

RESULTS

During the follow-up, 159 men were hospitalized due to HF. Baseline levels of all ISPs, except for haptoglobin, were significantly higher in men who developed HF. After adjustments for confounding factors, the hazard ratios (HR) of HF were 1.00 (reference), 1.7 (95% CI: 1.1-2.7), 2.0 (CI: 1.2-3.3) and 2.6 (CI: 1.6-4.1), respectively, in men with none, one, two and three or more ISPs in the 4th quartile (trend: p<0.001). Of the individual ISPs, fibrinogen, ceruloplasmin and alpha1-antitrypsin showed significant relationships with incidence of HF after adjustment for risk factors.

CONCLUSION

Plasma levels of inflammatory markers are associated with long-term incidence of hospitalizations due to HF in middle-aged men.

Independent prediction of metabolic syndrome by plasma fibrinogen in men, and predictors of elevated levels

The role of plasma fibrinogen levels in predicting metabolic syndrome (MetS) and assessment of determinants of these levels were investigated. A total of 2234 men and women, aged 49+/-12 years, representative of Turkish adults who had plasma fibrinogen determinations, were prospectively evaluated and followed for a mean of 6.6 years. The modified Clauss method was used for assays. MetS was defined by ATPIII criteria modified for male abdominal obesity. MetS cases at baseline were excluded in prospective analyses. Median (interquartile range) fibrinogen values were 2.87 (2.29; 3.56) g/L. Fibrinogen levels predicted significantly newly developing MetS in men (RR 1.40 [95%CI 1.07; 1.83] for a 2-fold increment), after adjustment for age and smoking status, and (RR 1.32 [95%CI 0.95; 1.83] again for doubling), after additional adjustment for all 5 components of MetS. MetS was not significantly predicted by fibrinogen levels in women in either multivariable model. By regression analysis of eight covariates, not waist circumference, but systolic blood pressure, current smoking and C-reactive protein (CRP) in men, and age in women were predictors of elevated (>3.0 g/L) fibrinogen at follow-up (p<0.05 in all).

CONCLUSIONS

Plasma fibrinogen predicts MetS independently of its components in men, in contradistinction to women, and, hence, is likely one of its components. Hyperfibrinogenemia representing an inflammatory state is postulated as the underlying mechanism. Central obesity is linked to elevation in fibrinogen mainly through the mediation of blood pressure, CRP, and via being affected by cigarette smoking.

Carotid plaque, stroke pathogenesis, and CRP: treatment of ischemic stroke

C-reactive protein (CRP), an inflammatory marker, has been identified as a likely predictor of the risk of a future stroke. In clinical settings, it has been consistently observed that higher concentrations of CRP are associated with larger brain infarcts and worst neurologic outcome. However, there is still controversy over the degree of risk conferred by elevated CRP concentrations. CRP, like many other hemostatic factors, is an acute-phase protein and, therefore, it is not always clear whether its association with cerebrovascular disease reflects its contribution to atherothrombosis, its acute-phase condition, or both. Whether a reduction of CRP levels could be beneficial to stroke patients remains to be clarified. More studies are needed before CRP becomes a routine part of the evaluation of stroke patients.

Fibrinogen gene variation and ischemic stroke

BACKGROUND

Plasma fibrinogen level and fibrin clot structure are heritable traits that may be of importance in the pathogenesis of ischemic stroke.

OBJECTIVES

To investigate associations between variation in the fibrinogen gamma (FGG), alpha (FGA) and beta (FGB) genes, fibrinogen level, and ischemic stroke.

METHODS

The Sahlgrenska Academy Study on Ischemic Stroke comprises 600 cases and 600 matched population controls. Stroke subtypes were defined according to TOAST criteria. Plasma fibrinogen level was measured by an automated clot-rate assay. Eight tagging single nucleotide polymorphisms (SNPs) were selected to capture genetic variation in the FGA, FGG, and FGB genes.

RESULTS

Plasma fibrinogen was independently associated with overall ischemic stroke and all subtypes, both in the acute stage (P < 0.001) and at three-month follow-up (P < 0.05). SNPs belonged to two haplotype blocks, one containing the FGB gene and the other the FGG and FGA genes. FGB haplotypes were associated with fibrinogen level (P < 0.01), but not with ischemic stroke. In contrast, FGG/FGA haplotypes showed independent association to ischemic stroke but not to fibrinogen level. In an additive model with the most common FGG/FGA haplotype (A1) as reference, the adjusted odds ratios of ischemic stroke were 1.4 [95% confidence interval (95% CI) 1.1-1.8], P < 0.01, 1.4 (95% CI 1.0-1.8), P < 0.05, and 1.5 (95% CI 1.0-2.1), P < 0.05 for the A2, A3, and A4 FGG/FGA haplotypes, respectively.

CONCLUSION

FGG/FGA haplotypes show association to ischemic stroke. This association is independent of fibrinogen level, thus suggesting that the association between ischemic stroke and variation at the FGG/FGA genes is mediated by qualitative rather than quantitative effects on fibrin(ogen).

Physical activity and fibrinogen concentrations in 23,201 men and women in the EPIC-Norfolk population-based study

OBJECTIVE

To examine the relationship between usual physical activity and fibrinogen concentrations in a free-living population of men and women.

METHODS AND RESULTS

We examined the cross-sectional relationship between habitual combined work and leisure physical activity derived from a validated physical activity questionnaire and plasma fibrinogen concentrations in a population-based study of 23,201 men and women aged 40-79 years. Mean plasma fibrinogen concentrations were lower in people who were physically active compared to those who were physically less active. Mean fibrinogen concentrations were 2.82+/-0.02, 2.87+/-2.87(0.02), 2.90+/-0.02, and 2.97+/-0.02g/L (p for trend<0.0001) for men in the active, moderately active, moderately inactive and inactive physical activity categories respectively, independently of age, smoking, body mass index (BMI), prevalent illnesses, social class and alcohol consumption. The corresponding values for women were 2.95+/-0.02, 2.94+/-0.01, 2.98+/-0.01, and 3.04+/-0.01g/L (p for trend<0.0001). Similar results were observed after adjusting for hormone replacement therapy (HRT) in women.

CONCLUSIONS

Higher physical activity is significantly inversely associated with plasma fibrinogen concentration independently of other related factors. This might provide an additional plausible mechanism for the cardiovascular health benefits of physical activity.

Effects of GH treatment in GH-deficient adults on adiponectin, leptin and pregnancy-associated plasma protein-A

OBJECTIVE

GH deficiency (GHD) in adults is associated with adverse effects on metabolism and increased cardiovascular risk. Pregnancy-associated plasma protein-A (PAPP-A) is a protease that promotes IGF-I availability in vascular tissues. PAPP-A levels appear to correlate with carotid intima-media thickness and have been proposed as an early predictor of cardiac events. The aim of our study was to evaluate PAPP-A levels in GHD adults at baseline and after GH replacement and correlate them with changes in body composition, lipid profile, glucose homeostasis, inflammatory markers and in leptin and adiponectin.

PATIENTS AND METHODS

Fourteen GHD adults were evaluated at baseline and after 1 year of GH therapy. All patients were compared at baseline with 28 age-, sex- and body mass index (BMI)-matched control subjects.

RESULTS

At baseline, GHD adults showed higher PAPP-A levels (P=0.03) and higher leptin (P=0.04), fibrinogen (P=0.002) and highly sensitive C-reactive protein (P=0.01) values than controls. Therapy with GH reduced PAPP-A (P=0.03) and fibrinogen levels (P=0.002) while increased BMI (P=0.01) and reduced waist-hip ratio (WHR; P=0.05) were observed. Insulin and homeostasis model assessment of insulin resistance index increased after treatment (P<0.004/P=0.007), without changes in leptin or adiponectin levels. PAPP-A values correlated positively with BMI and WHR and negatively with adiponectin before and after treatment, with no correlation with glucose homeostasis parameters, lipid profile or leptin.

CONCLUSIONS

Our study suggests that PAPP-A expression is increased in GHD adults, and that 1 year of GH replacement therapy is able to reduce PAPP-A levels in this population. However, further studies are required to determine whether this decrease correlates with an improvement in atherosclerosis.

High levels of inflammatory biomarkers are associated with increased allele-specific apolipoprotein(a) levels in African-Americans

BACKGROUND

A role of inflammation for cardiovascular disease (CVD) is established. Lipoprotein(a) [Lp(a)] is an independent CVD risk factor where plasma levels are determined by the apolipoprotein(a) [apo(a)] gene, which contains inflammatory response elements.

DESIGN

We investigated the effect of inflammation on allele-specific apo(a) levels in African-Americans and Caucasians. We determined Lp(a) levels, apo(a) sizes, allele-specific apo(a) levels, fibrinogen and C-reactive protein (CRP) levels in 167 African-Americans and 259 Caucasians.

RESULTS

Lp(a) levels were increased among African-Americans with higher vs. lower levels of CRP [<3 vs. > or =3 mg/liter (143 vs. 108 nmol/liter), P = 0.009] or fibrinogen (<340 vs. > or =340 mg/liter, P = 0.002). We next analyzed allele-specific apo(a) levels for different apo(a) sizes. No differences in allele-specific apo(a) levels across CRP or fibrinogen groups were seen among African-Americans or Caucasians for small apo(a) sizes (<22 kringle 4 repeats). Allele-specific apo(a) levels for medium apo(a) sizes (22-30 kringle 4 repeats) were significantly higher among African-Americans, with high levels of CRP or fibrinogen compared with those with low levels (88 vs. 67 nmol/liter, P = 0.014, and 91 vs. 59 nmol/liter, P < 0.0001, respectively). No difference was found for Caucasians.

CONCLUSIONS

Increased levels of CRP or fibrinogen are associated with higher allele-specific medium-sized apo(a) levels in African-Americans but not in Caucasians. These findings indicate that proinflammatory conditions result in a selective increase in medium-sized apo(a) levels in African-Americans and suggest that inflammation-associated events may contribute to the interethnic difference in Lp(a) levels between African-Americans and Caucasians.

Association of antiretroviral therapy with fibrinogen levels in HIV-infection

BACKGROUND

HIV infection is associated with an increased risk of coronary artery disease, but the contribution of inflammation versus antiretroviral drugs is not well understood. Fibrinogen is an inflammatory factor associated with atherosclerosis.

METHODS

A total of 1131 HIV-infected patients and 281 controls [from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a population-based study of cardiovascular risk assessment] in the Study of Fat Redistribution and Metabolic Change in HIV infection (FRAM) had plasma fibrinogen levels measured. Multivariable linear regression identified factors associated with fibrinogen.

RESULTS

HIV-infected patients had higher levels of fibrinogen compared with controls (males: 25 mg/dl higher, P = 0.006; females: 21 mg/dl higher, P = 0.39). Among HIV-infected persons, median levels of fibrinogen were 11% higher in patients currently using any protease inhibitor (PI) compared with those not using a PI (P < 0.0001). The strongest univariate associations were with the individual PIs, ritonavir and indinavir. Patients taking indinavir boosted with ritonavir had median fibrinogen levels 8% higher than those on indinavir alone (P = 0.049). Lower levels of fibrinogen were seen in those HIV-infected patients currently using any nonnucleoside reverse transcriptase inhibitor (NNRTI) compared to those not using an NNRTI (nevirapine -14.4%, P < 0.0001; efavirenz -7%, P = 0.0002). The associations of ritonavir, indinavir, efavirenz and nevirapine with fibrinogen levels persisted after multivariable analysis and were independent of other antiretroviral use.

CONCLUSION

Protease inhibitor use is associated with elevated fibrinogen levels which may contribute to increased risk of atherosclerosis in HIV-infected patients. Conversely, NNRTI use is associated with lower fibrinogen levels which may decrease risk of atherosclerosis.

Associations of plasma pro-inflammatory cytokines, fibrinogen, viscosity and C-reactive protein with cardiovascular risk factors and social deprivation: the fourth Glasgow MONICA study

Circulating inflammatory markers [plasma fibrinogen, viscosity and C-reactive protein (CRP)] have been associated with cardiovascular risk factors. In part, these associations may reflect 'upstream' changes in pro-inflammatory cytokines - interleukin (IL)-6, IL-18 and tumour necrosis factor (TNF)alpha. These variables were measured in 1666 men and women aged 25-64 years and their associations with risk factors were studied. All six markers increased significantly with age. IL-18 and TNFalpha levels were higher, and fibrinogen levels lower, in males. Oral contraceptive use increased levels of CRP, whilst postmenopausal women had elevated IL-18 levels. Inflammatory markers were also associated with components of the metabolic syndrome. Most inflammatory markers showed an increasing trend with alcohol consumption in men and a decreasing trend in women, and increasing trends with level of smoking. Inflammatory markers generally showed strong positive associations with social deprivation. After adjustment for classical risk factors, IL-6, IL-18 and TNFalpha retained significant associations with social deprivation only in men (P < 0.008). We conclude that pro-inflammatory cytokines are associated with several cardiovascular risk factors including social deprivation, and may mediate some of their associations with 'downstream' inflammatory markers (fibrinogen, viscosity and CRP).

Oral melatonin reduces blood coagulation activity: a placebo-controlled study in healthy young men

Melatonin has previously been suggested to affect hemostatic function but studies on the issue are scant. We hypothesized that, in humans, oral administration of melatonin is associated with decreased plasma levels of procoagulant hemostatic measures compared with placebo medication and that plasma melatonin concentration shows an inverse association with procoagulant measures. Forty-six healthy men (mean age 25 +/- 4 yr) were randomized, single-blinded, to either 3 mg of oral melatonin (n = 25) or placebo medication (n = 21). One hour thereafter, levels of melatonin, fibrinogen, and D-dimer as well as activities of coagulation factor VII (FVII:C) and VIII (FVIII:C) were measured in plasma. Multivariate analysis of covariance and regression analysis controlled for age, body mass index, mean arterial blood pressure, heart rate, and norepinephrine plasma level. Subjects on melatonin had significantly lower mean levels of FVIII:C (81%, 95% CI 71-92 versus 103%, 95% CI 90-119; P = 0.018) and of fibrinogen (1.92 g/L, 95% CI 1.76-2.08 versus 2.26 g/L, 95% CI 2.09-2.43; P = 0.007) than those on placebo explaining 14 and 17% of the respective variance. In all subjects, increased plasma melatonin concentration independently predicted lower levels of FVIII:C (P = 0.037) and fibrinogen (P = 0.022) explaining 9 and 11% of the respective variance. Melatonin medication and plasma concentration were not significantly associated with FVII:C and D-dimer levels. A single dose of oral melatonin was associated with lower plasma levels of procoagulant factors 60 min later. There might be a dose-response relationship between the plasma concentration of melatonin and coagulation activity.

Correlates of plasma fibrinogen (FG) levels in a random sample of community-dwelling elderly

The aim of this study was to evaluate the association between plasma FG levels and coexisting cardiovascular diseases (CVD) risk factors, comorbidities, functional status and cognitive function in a random sample of 270 (163 women and 107 men) community-dwelling elderly aged 65-79 years. The assessment included demographic and social variables, health status, nutritional state, physical and cognitive function. Physical activity was assessed by the Stanford Usual Activity Questionnaire. The average plasma FG level was lower in men 3.1+/-0.9 g/l (+/-SD) than in women 3.6+/-1.1g/l. In the whole group of elderly people, body mass index (BMI), percentage of body fat, calf circumference as well as total and low density cholesterol were positively correlated with FG levels, whereas the Stanford Moderate Index-negatively. Multifactor analysis of variance (ANOVA) revealed that female gender, calf circumference and the Stanford Moderate Index are the factors that independently predict FG levels. In conclusion, FG seems not to be related to functional status or cognitive function of older individuals. Nevertheless, our findings suggest that female gender, excess body fatness and low physical activity have an independent contribution to higher plasma FG levels in community-dwelling older subjects.

Relationship between plasma sialic acid and fibrinogen concentration and incident micro- and macrovascular complications in type 1 diabetes. The EURODIAB Prospective Complications Study (PCS)

AIMS/HYPOTHESIS

Type 1 diabetes is associated with an increased risk of vascular complications. This increased risk could be explained by sialic acid and/or fibrinogen. It is also not clear what explains the abolition of sex-related differences affecting risk of CHD in the presence of type 1 diabetes. Therefore, we examined whether fibrinogen and sialic acid are related to incident micro- and macrovascular complications in patients with type 1 diabetes.

METHODS

A subset (n=2329) of the EURODIAB Prospective Complications Study was analysed. Sialic acid and fibrinogen concentrations were measured at baseline. The main outcomes after 7 years were development of albuminuria, retinopathy, neuropathy and CHD.

RESULTS

Univariable and multivariable models using Cox proportional survival analyses showed that an SD unit increase in sialic acid and fibrinogen levels was significantly associated with CHD in men only. Adjusted standardised hazard ratios (sHRs) were 1.50 (95% CI 1.05-2.15) and 1.40 (95% CI 1.06-1.86) for sialic acid and fibrinogen, respectively. Initial associations between (1) sialic acid and incident retinopathy [standardised odds ratio (sOR) men 1.68, 95% CI 1.10-2.57], (2) fibrinogen and retinopathy (sOR women 1.37, 95% CI 1.06-1.78) and (3) sialic acid and neuropathy (sOR men 1.37, 95% CI 1.06-1.77) were shown, but became non-significant in multivariable models.

CONCLUSIONS/INTERPRETATION

Sialic acid and fibrinogen are strong predictors of CHD in men with type 1 diabetes, beyond the effect of established risk factors. The associations found with microvascular complications were not independent of other risk factors.

Glycohaemoglobin as a determinant of increased fibrinogen concentrations and low-grade inflammation in apparently healthy nondiabetic individuals

OBJECTIVE

To determine the potential role of glycohaemoglobin as a possible determinant of increased fibrinogen concentrations and low-grade inflammation in a group of apparently healthy, nondiabetic individuals not expressing clinically overt atherothrombosis.

DESIGN AND MAIN OUTCOME MEASURES

We performed a cross-sectional analysis of the concentrations of glycohaemoglobin alongside the concentrations of quantitative fibrinogen and high-sensitivity C-reactive protein (hs-CRP). In all, 1511 males and 757 apparently healthy females, without diabetes mellitus or clinically evident atherothrombotic disease, were enrolled in the study during their routine annual health check-up.

RESULTS

Glycohaemoglobin entered the linear regression models as a significant determinant of quantitative fibrinogen in both genders and of hs-CRP in men. We found this to be true even following the inclusion of multiple variables known to influence the intensity of low-grade inflammation, such as age, gender, waist circumference, body mass index, blood pressure, medications, hormone therapy, glucose levels (normal or impaired fasting glucose), smoking habits, family history of coronary artery disease, lipid profile as well as alcohol consumption and sports intensity. We found glycohaemoglobin to be a significant determinant of fibrinogen concentrations in apparently healthy nondiabetic individuals not yet presenting with evident atherothrombosis.

CONCLUSIONS

This observation supports the idea that glycohaemoglobin might have an effect on fibrinogen concentrations in both genders and on hs-CRP in men. Moreover, our results suggest that glycohaemoglobin should be perceived as a continuous variable without a 'normal' cut-off point, as it may exhibit a detrimental role even when present in relatively low levels.

Non-traditional markers of atherosclerosis potentiate the risk of coronary heart disease in patients with type 2 diabetes and metabolic syndrome

BACKGROUND AND AIMS

The aims of this study were to establish the prevalence of metabolic syndrome (MS), in type 2 diabetes mellitus (DM), according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria, and to assess the association of MS with other cardiovascular (CV) risk factors in these patients.

METHODS AND RESULTS

A cross-sectional study was conducted in 1610 patients with type 2 DM. Glycated hemoglobin A1c (HbA1c), total cholesterol, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), uric acid, fibrinogen, creatinine, and albumin/creatinine ratios were measured. The risk of coronary heart disease (CHD) was calculated using the UKPDS Risk Engine. Seventy percent of the diabetic population met the criteria for MS; central obesity and hypertension were the most common criteria. Subjects with MS had higher levels of HbA1c, LDL-C, non-HDL-C, uric acid, and fibrinogen compared to patients without MS. Similarly, microalbuminuria and a high triglyceride (Tg)/HDL-C ratio (a marker of small LDL-C) occurred more frequently in patients with MS. When patients with no history of CHD events were considered, mean CHD risk was greater in those with, than those without, MS.

CONCLUSIONS

MS is highly prevalent in type 2 DM and is commonly associated with non-traditional CV risk factors. The diagnosis of MS seems to confer additional CHD risk in patients with type 2 diabetes.

Fibrinogen induces endothelial cell permeability

Many cardiovascular and cerebrovascular disorders are accompanied by an increased blood content of fibrinogen (Fg), a high molecular weight plasma adhesion protein. Fg is a biomarker of inflammation and its degradation products have been associated with microvascular leakage. We tested the hypothesis that at pathologically high levels, Fg increases endothelial cell (EC) permeability through extracellular signal regulated kinase (ERK) signaling and by inducing F-actin formation. In cultured ECs, Fg binding to intercellular adhesion molecule-1 and to alpha(5)beta(1) integrin, caused phosphorylation of ERK. Subsequently, F-actin formation increased and coincided with formation of gaps between ECs, which corresponded with increased permeability of ECs to albumin. Our data suggest that formation of F-actin and gaps may be the mechanism for increased albumin leakage through the EC monolayer. The present study indicates that elevated un-degraded Fg may be a factor causing microvascular permeability that typically accompanies cardiovascular and cerebrovascular disorders.

Effect of age and glycaemic control on the association between fibrinogen and risk of acute coronary events after transient ischaemic attack or stroke

BACKGROUND

Fibrinogen is an independent risk factor for acute vascular events, but there is uncertainty as to whether it is causal. One potential causal mechanism is the formation of low permeability fibrin clot in association with raised fibrinogen. We hypothesised that if this effect of fibrinogen were causally related to risk of vascular events, the risk relationship would be affected by the two other factors that affect fibrin clot permeability - age and glycaemic control.

METHODS

We studied the relationship between fibrinogen and risk of incident coronary events by age and baseline glucose levels in pooled data from three cohorts of patients with known cerebrovascular disease (UK-TIA Aspirin trial; Dutch TIA trial; Oxford TIA Study) during 23,272 patient-years of follow-up.

RESULTS

Risk of coronary events increased linearly with fibrinogen, but there was a significant interaction with age (p = 0.01 across tertiles of age), with the association being strongest for individuals aged <60 years (upper fibrinogen quintile hazard ratio = 3.95, 95% CI = 2.67-5.85, p < 0.0001). The risk relation was diminished in individuals with impaired glucose tolerance or diabetes. The effects of age and glycaemic control were independent, such that there was an almost fivefold increase in risk across quintiles of fibrinogen in patients aged <60 years with below median normal glucose levels (upper quintile hazard ratio = 4.90, 95% CI = 2.79-8.58, p < 0.0001).

CONCLUSIONS

The effect of age and glycaemic control on the relationship between fibrinogen and risk of acute coronary events supports the hypothesis of a causal effect of fibrinogen mediated via the permeability of fibrin clot.

Do plasma biomarkers of coagulation and fibrinolysis differ between patients who have experienced an acute myocardial infarction versus stable exertional angina?

BACKGROUND

Circulating concentrations of proteins associated with coagulation and fibrinolysis may differ between individuals with coronary artery disease (CAD) who develop an acute myocardial infarction (AMI) rather than stable exertional angina.

METHODS

We compared plasma concentrations of fibrinogen, d-dimer, tissue-type plasminogen activator, and plasminogen activator inhibitor-1 (PAI-1) between patients whose first clinical manifestation of CAD was an AMI (n = 198) rather than stable exertional angina (n = 199). We also compared plasma concentrations of these proteins between patients with symptomatic CAD (either AMI or stable angina; n = 397) and healthy, control subjects (n = 197) to confirm the sensitivity of these assays to detect epidemiologic associations.

RESULTS

At a median of 15 weeks after presentation, patients with AMI had slightly higher d-dimer concentrations than patients with stable angina (P = .057), but were not significantly different in other markers. By contrast, fibrinogen, d-dimer, and tissue-type plasminogen activator were significantly higher (P < .001) and PAI-1 lower in patients with CAD than in healthy control subjects. After statistical adjustment for clinical covariates, cardiac risk factors, medications, and other confounders, fibrinogen, d-dimer, and PAI-1 remained significantly associated with CAD.

CONCLUSION

Selected plasma markers of coagulation and fibrinolysis did not distinguish patients presenting with AMI from those with stable exertional angina.

From vulnerable plaque to vulnerable patient: the search for biomarkers of plaque destabilization

There is a strong need for biomarkers to identify patients at risk for future cardiovascular events related with progressive atherosclerotic disease. Ideally, increasing knowledge of the mechanisms of atherosclerotic plaque destabilization should be translated in clinical practice. Currently, the following commonly followed strategies can be identified with the objective to detect either the local vulnerable plaque that is prone to rupture and gives rise to a thrombotic occlusion, or the systemic vulnerable patient, who has a high probability to suffer from an adverse clinical event. On the one hand, studies are ongoing to determine local atherosclerotic plaque characteristics to predict future local plaque rupture and subsequent vascular thrombosis. Newly developed imaging modalities are being developed and validated to detect these plaques in vivo. On the other hand, systemic approaches are pursued to discover serum biomarkers that are applicable to define patients at risk for future cardiovascular events. We propose a third original approach that is optional but yet unexplored, that is, to use local plaque characteristics as a biomarker not just for local plaque destabilization but for future cardiovascular events due to plaque progression in any vascular system. This review aims to provide an overview of the current standings of the identification of the vulnerable plaque and the vulnerable patient.

C-reactive protein and fibrinogen in acute stroke patients with and without sleep apnea

BACKGROUND AND PURPOSE

Although sleep apnea (SA) is a risk factor for ischemic stroke and an important prognosticator in affected patients, the exact pathophysiological link between SA and stroke remains to be established. We investigated whether levels of C-reactive protein (CRP) and fibrinogen are increased in patients with acute stroke and SA compared with stroke patients without SA.

PATIENTS AND METHODS

117 consecutive patients with ischemic stroke admitted to our stroke unit within 12 h after stroke onset were included in this study. On admission, CRP and fibrinogen levels were determined. All patients received cardiorespiratory polygraphy during the first 72 h of their hospital stay. In all patients, demographic data, National Institutes of Health Stroke Scale score and cerebrovascular risk factors were assessed.

RESULTS

SA defined by an apnea-hypopnea index (AHI) of > or =10/h was found in 64 (55%) patients. Elevated CRP and fibrinogen levels were seen twice as often in patients with SA than in patients without (CRP: 52 vs. 26%; fibrinogen: 72 vs. 37%). After multivariate logistic regression analysis, an AHI of > or =10/h was independently correlated with raised levels of both of these parameters.

CONCLUSION

SA is independently associated with raised levels of CRP and fibrinogen in patients with acute ischemic stroke. We assume that both proteins are part of the pathophysiological pathway linking SA to stroke.

The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases

Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.

Elevated plasminogen activator inhibitor 1 in sleep apnea and its relation to the metabolic syndrome: an investigation in 2 different study samples

Increased circulating levels of plasminogen activator inhibitor 1 (PAI-1) have been associated with atherothrombosis. Plasminogen activator inhibitor 1 levels are elevated in obstructive sleep apnea (OSA) and in the metabolic syndrome, both of which confer excess coronary risk. We investigated whether apnea-hypopnea index (AHI) and the metabolic syndrome would interact in determining plasma concentration of PAI-1. Full-night polysomnography was performed in 2 different groups consisting of a total of 180 unmedicated apneic and nonapneic subjects of whom 20% met the diagnostic criteria for the metabolic syndrome. Distinct AHI cutoffs were selected to define 3 OSA groups with different apnea severity: (a) AHI of at least 5 (n = 115), (b) AHI of at least 10 (n = 84), and (c) AHI of at least 15 (n = 72). Plasminogen activator inhibitor 1 concentration was determined in plasma and statistical analyses controlled for age, sex, ethnicity, and smoking status. In both study groups, PAI-1 was positively correlated with AHI (P's < .002) and was also higher in subjects with the metabolic syndrome than in those without (P' < .013). The interaction between AHI and the metabolic syndrome independently predicted PAI-1 across all subjects and in all 3 OSA groups (P < .05). The AHI was not a significant predictor of PAI-1 in the presence of the metabolic syndrome. If the metabolic syndrome was absent, AHI accounted for between 10% and 13% of the variance in PAI-1 across all subjects and in all 3 OSA severity groups (P < .05). In conclusion, more severe apnea was independently associated with higher PAI-1 concentration in subjects without the metabolic syndrome. Once the metabolic syndrome is clinically manifest, it may be more important than apnea in determining PAI-1 levels.