Mark Roest

Antiphospholipid antibodies and risk of myocardial infarction and ischaemic stroke in young women in the RATIO study: a case-control study

BACKGROUND Arterial thrombosis is a major clinical manifestation of the antiphospholipid syndrome, which is an autoimmune disease found mostly in young women. Although the presence of circulating antiphospholipid antibodies in individuals who have a thrombotic event is a prerequisite for the diagnosis of the antiphospholipid syndrome, the risk of arterial thrombosis associated with antiphospholipid antibodies in the general population is unclear. METHODS In RATIO (Risk of Arterial Thrombosis In relation to Oral contraceptives), a large multicentre population-based case-control study, we enrolled women aged under 50 years who were admitted to hospital at 16 centres with first ischaemic stroke or myocardial infarction between January, 1990, and October, 1995. An additional 59 women who presented with ischaemic stroke at the University Medical Centre Utrecht between 1996 and 2001 were also enrolled. Information on cardiovascular risk factors (such as oral contraceptive use, smoking, and hypertension) were assessed with a standard questionnaire. During the second phase (1998-2002), blood samples were taken to measure antiphospholipid antibody profiles (lupus anticoagulant, anticardiolipin IgG, anti-beta(2)-glycoprotein I IgG, and antiprothrombin IgG) and to determine genetic prothrombotic risk factors (factor V G1691A variant, prothrombin G20210A variant, and factor XIII 204Phe allele). FINDINGS 175 patients with ischaemic stroke, 203 patients with myocardial infarction, and 628 healthy controls were included. Patients were frequency matched with controls for age, residence area, and index year. Lupus anticoagulant was found in 30 (17%) patients with ischaemic stroke, six (3%) patients with myocardial infarction, and four (0.7%) in the control group. The odds ratio for myocardial infarction was 5.3 (95% CI 1.4-20.8), which increased to 21.6 (1.9-242.0) in women who used oral contraceptives and 33.7 (6.0-189.0) in those who smoked. The odds ratio for ischaemic stroke was 43.1 (12.2-152.0), which increased to 201.0 (22.1-1828.0) in women who used oral contraceptives and 87.0 (14.5-523.0) in those who smoked. In women who had anti-beta(2)-glycoprotein I antibodies, the risk of ischaemic stroke was 2.3 (1.4-3.7), but the risk of myocardial infarction was not increased (0.9, 0.5-1.6). Neither anticardiolipin nor antiprothrombin antibodies affected the risk of myocardial infarction or ischaemic stroke. INTERPRETATION Our results suggest that lupus anticoagulant is a major risk factor for arterial thrombotic events in young women, and the presence of other cardiovascular risk factors increases the risk even further. FUNDING Netherlands Heart Foundation and Leducq Foundation.

Heterozygosity for a Hereditary Hemochromatosis Gene Is Associated With Cardiovascular Death in Women

Background-The genetic background of hereditary hemochromatosis (HH) is homozygosity for a cysteine-to-tyrosine transition at position 282 in the HFE gene. Heterozygosity for HH is associated with moderately increased iron levels and could be a risk factor for cardiovascular death. Methods and Results-We studied the relation between HH heterozygosity and cardiovascular death in a cohort study among 12 239 women 51 to 69 years of age residing in Utrecht, the Netherlands. Women were followed for 16 to 18 years (182 976 follow-up years). The allele prevalence of the HH gene in the reference group was 4.0 (95% CI 2.9 to 5.4). The mortality rate ratios for HH heterozygotes compared with wild types was 1.5 (95% CI 0.9 to 2.5) for myocardial infarction (n=242), 2.4 (95% CI 1.3 to 3. 5) for cerebrovascular disease (n=118), and 1.6 (95% CI 1.1 to 2.4) for total cardiovascular disease (n=530). The population-attributable risks of HH heterozygosity for myocardial infarction and cerebrovascular and total cardiovascular death were 3. 3%, 8.8%, and 4.0%, respectively. In addition, we found evidence for effect modification by hypertension and smoking. Conclusions-We found important evidence that inherited variation in iron metabolism is involved in cardiovascular death in postmenopausal women, especially in women already carrying classic risk factors.

Effect modification by population dietary folate on the association between MTHFR genotype, homocysteine, and stroke risk: a meta-analysis of genetic studies and randomised trials

Summary Background The MTHFR 677C→T polymorphism has been associated with raised homocysteine concentration and increased risk of stroke. A previous overview showed that the effects were greatest in regions with low dietary folate consumption, but differentiation between the effect of folate and small-study bias was difficult. A meta-analysis of randomised trials of homocysteine-lowering interventions showed no reduction in coronary heart disease events or stroke, but the trials were generally set in populations with high folate consumption. We aimed to reduce the effect of small-study bias and investigate whether folate status modifies the association between MTHFR 677C→T and stroke in a genetic analysis and meta-analysis of randomised controlled trials. Methods We established a collaboration of genetic studies consisting of 237 datasets including 59 995 individuals with data for homocysteine and 20 885 stroke events. We compared the genetic findings with a meta-analysis of 13 randomised trials of homocysteine-lowering treatments and stroke risk (45 549 individuals, 2314 stroke events, 269 transient ischaemic attacks). Findings The effect of the MTHFR 677C→T variant on homocysteine concentration was larger in low folate regions (Asia; difference between individuals with TT versus CC genotype, 3·12 μmol/L, 95% CI 2·23 to 4·01) than in areas with folate fortification (America, Australia, and New Zealand, high; 0·13 μmol/L, −0·85 to 1·11). The odds ratio (OR) for stroke was also higher in Asia (1·68, 95% CI 1·44 to 1·97) than in America, Australia, and New Zealand, high (1·03, 0·84 to 1·25). Most randomised trials took place in regions with high or increasing population folate concentrations. The summary relative risk (RR) of stroke in trials of homocysteine-lowering interventions (0·94, 95% CI 0·85 to 1·04) was similar to that predicted for the same extent of homocysteine reduction in large genetic studies in populations with similar folate status (predicted RR 1·00, 95% CI 0·90 to 1·11). Although the predicted effect of homocysteine reduction from large genetic studies in low folate regions (Asia) was larger (RR 0·78, 95% CI 0·68 to 0·90), no trial has evaluated the effect of lowering of homocysteine on stroke risk exclusively in a low folate region. Interpretation In regions with increasing levels or established policies of population folate supplementation, evidence from genetic studies and randomised trials is concordant in suggesting an absence of benefit from lowering of homocysteine for prevention of stroke. Further large-scale genetic studies of the association between MTHFR 677C→T and stroke in low folate settings are needed to distinguish effect modification by folate from small-study bias. If future randomised trials of homocysteine-lowering interventions for stroke prevention are undertaken, they should take place in regions with low folate consumption. Funding Full funding sources listed at end of paper (see Acknowledgments).

Proteome-wide Analysis and CXCL4 as a Biomarker in Systemic Sclerosis

BACKGROUND Plasmacytoid dendritic cells have been implicated in the pathogenesis of systemic sclerosis through mechanisms beyond the previously suggested production of type I interferon. METHODS We isolated plasmacytoid dendritic cells from healthy persons and from patients with systemic sclerosis who had distinct clinical phenotypes. We then performed proteome-wide analysis and validated these observations in five large cohorts of patients with systemic sclerosis. Next, we compared the results with those in patients with systemic lupus erythematosus, ankylosing spondylitis, and hepatic fibrosis. We correlated plasma levels of CXCL4 protein with features of systemic sclerosis and studied the direct effects of CXCL4 in vitro and in vivo. RESULTS Proteome-wide analysis and validation showed that CXCL4 is the predominant protein secreted by plasmacytoid dendritic cells in systemic sclerosis, both in circulation and in skin. The mean (±SD) level of CXCL4 in patients with systemic sclerosis was 25,624±2652 pg per milliliter, which was significantly higher than the level in controls (92.5±77.9 pg per milliliter) and than the level in patients with systemic lupus erythematosus (1346±1011 pg per milliliter), ankylosing spondylitis (1368±1162 pg per milliliter), or liver fibrosis (1668±1263 pg per milliliter). CXCL4 levels correlated with skin and lung fibrosis and with pulmonary arterial hypertension. Among chemokines, only CXCL4 predicted the risk and progression of systemic sclerosis. In vitro, CXCL4 down-regulated expression of transcription factor FLI1, induced markers of endothelial-cell activation, and potentiated responses of toll-like receptors. In vivo, CXCL4 induced the influx of inflammatory cells and skin transcriptome changes, as in systemic sclerosis. CONCLUSIONS Levels of CXCL4 were elevated in patients with systemic sclerosis and correlated with the presence and progression of complications, such as lung fibrosis and pulmonary arterial hypertension. (Funded by the Dutch Arthritis Association and others.).

Plasminogen Activator Inhibitor 4G Polymorphism Is Associated With Decreased Risk of Cerebrovascular Mortality in Older Women

BACKGROUND A common 4G allele of a 4G/5G polymorphism in the promoter region of the plasminogen activator inhibitor-1 (PAI-1) gene is associated with increased transcription of the PAI-1 protein, which may lead to decreased fibrinolysis. It has therefore been proposed as a candidate risk factor for myocardial infarction or stroke. METHODS AND RESULTS We studied the relationship between PAI-1 4G/5G genotype and the risk of cardiovascular mortality in a prospective cohort study among 12 239 women initially aged between 52 and 67 years, with a maximum follow-up time of 18 years (153 732 follow-up years). PAI-1 4G/5G genotype was measured in DNA obtained from urine samples, which were collected at baseline, of 498 women who died of a cardiovascular disease and a random sample of 512 women from the same cohort who did not die of cardiovascular disease. The PAI-1 4G/5G genotype was not associated with risk of myocardial infarction or other cardiovascular mortality. However, PAI-1 4G4G homozygotes had a markedly reduced risk of cerebrovascular mortality compared with PAI-1 5G5G homozygotes: the relative risk was 0.4, with a 95% CI of 0.2 to 0.7, whereas the relative risk of cerebrovascular mortality in PAI-1 4G5G heterozygotes compared with PAI-1 5G5G homozygotes was 0.7, with a 95% CI of 0.4 to 1.1. CONCLUSIONS These findings are suggestive of an important contribution of PAI-1 in cerebrovascular pathology, probably via pathways other than fibrinolysis. PAI-1 may protect against destabilization of the atherosclerotic plaque, or it may inhibit neurotoxicity of tissue plasminogen activator in the brain.

Homozygosity for 807 T Polymorphism in α2 Subunit of Platelet α2β1 Is Associated With Increased Risk of Cardiovascular Mortality in High-Risk Women

Background —Platelet adhesion to collagen is the initial step in both hemostasis and thrombosis; this adhesion is mediated by α 2 β 1 on the surface of platelet membranes. An 807 C to T single nucleotide exchange polymorphism close to the gene coding for the α 2 subunit of α 2 β 1 is associated with the density of α 2 β 1 on the platelet membrane. Methods and Results —We studied the relation of the α 2 β 1 807 C/T genotype to cardiovascular mortality in a prospective cohort study of 12 239 women who were invited for the breast cancer screening program of Utrecht, the Netherlands. The initial age was between 52 and 67 years. Women were followed on vital status between 1976 and 1995 (168 513 women-years). Data were analyzed by using a nested case-control design. The α 2 β 1 807 C/T genotype was not associated with cardiovascular mortality in the total population: the rate ratio for cardiovascular mortality in 807 TT homozygotes compared with 807 CC wild types was 1.2 (95% CI 0.8 to 1.7). However, the α 2 β 1 807 T polymorphism was associated with an increased risk of cardiovascular mortality in women who smoked or in women who had indications of compromised endothelium, such as diabetes and microalbuminuria. In those who were exposed to ≥2 of these factors, the risk ratio (95% CI) between α 2 β 1 807 TT homozygotes and 807 CC wild types was 14.1 (5.0 to 39.9). Conclusions —α 2 β 1 807 TT homozygosity, coding for increased α 2 β 1 density on the platelet membrane, is associated with an increased risk of cardiovascular mortality in those women with indications of compromised endothelium.

Factor V Leiden in central venous catheter-associated thrombosis

Summary. Subclavian vein thrombosis is a well‐recognized complication following central venous catheter insertion and is associated with significant morbidity. The factor V Leiden mutation is an important risk factor for deep venous thrombosis and pulmonary embolism. Whether this mutation also predisposes patients fitted with a central venous catheter to subclavian vein thrombosis is not known. The occurrence of central venous catheter‐associated thrombosis was investigated in 277 consecutive patients receiving an allogeneic bone marrow transplantation. All patients received a tunnelled double or triple catheter positioned in the subclavian vein. Catheter‐associated thrombosis was diagnosed on the basis of clinical signs of thrombosis, i.e. swelling and/or redness of the limb or venous engorgement and was confirmed with a colour‐flow Doppler ultrasound. Thirteen patients were heterozygous for the factor V Leiden mutation. Seven of these patients had a subclavian vein thrombosis (54%), while this occurred in only 9% of the factor V Leiden‐negative patients, corresponding with a relative risk of 7·7 (95% CI 3·3–17·9). Factor V Leiden is attributable for 17·3% of all thrombosis in patients with central venous catheters. The majority of patients with the factor V Leiden mutation with a central venous catheter will develop thrombosis. Patients with a factor V Leiden mutation should receive adequate thrombosis prophylaxis upon catheter introduction and the catheter should be removed immediately after the treatment. Based on this very high risk, we advise testing for factor V Leiden in all bone marrow transplantation patients receiving a central venous catheter.

Circulating Biomarkers for Predicting Cardiovascular Disease Risk; a Systematic Review and Comprehensive Overview of Meta-Analyses

Background Cardiovascular disease is one of the major causes of death worldwide. Assessing the risk for cardiovascular disease is an important aspect in clinical decision making and setting a therapeutic strategy, and the use of serological biomarkers may improve this. Despite an overwhelming number of studies and meta-analyses on biomarkers and cardiovascular disease, there are no comprehensive studies comparing the relevance of each biomarker. We performed a systematic review of meta-analyses on levels of serological biomarkers for atherothrombosis to compare the relevance of the most commonly studied biomarkers. Methods and Findings Medline and Embase were screened on search terms that were related to “arterial ischemic events” and “meta-analyses”. The meta-analyses were sorted by patient groups without pre-existing cardiovascular disease, with cardiovascular disease and heterogeneous groups concerning general populations, groups with and without cardiovascular disease, or miscellaneous. These were subsequently sorted by end-point for cardiovascular disease or stroke and summarized in tables. We have identified 85 relevant full text articles, with 214 meta-analyses. Markers for primary cardiovascular events include, from high to low result: C-reactive protein, fibrinogen, cholesterol, apolipoprotein B, the apolipoprotein A/apolipoprotein B ratio, high density lipoprotein, and vitamin D. Markers for secondary cardiovascular events include, from high to low result: cardiac troponins I and T, C-reactive protein, serum creatinine, and cystatin C. For primary stroke, fibrinogen and serum uric acid are strong risk markers. Limitations reside in that there is no acknowledged search strategy for prognostic studies or meta-analyses. Conclusions For primary cardiovascular events, markers with strong predictive potential are mainly associated with lipids. For secondary cardiovascular events, markers are more associated with ischemia. Fibrinogen is a strong predictor for primary stroke.

Serum Ferritin Is a Risk Factor for Stroke in Postmenopausal Women

Background and Purpose— Iron is an essential element for the human body. It has, however, been suggested that excessive iron stores may increase the risk of vascular disease. So far, epidemiologic studies on stroke are sparse. Methods— We studied the association between iron status and stroke risk in a population-based cohort of 11 471 Dutch postmenopausal women between 49 and 70 years of age. Women were included between 1993 and 1997 and followed up until January 1, 2000, for cerebrovascular events. We conducted a case-cohort study by using all stroke cases (n=63) and a random sample of the baseline cohort (n=1134). Serum ferritin, serum iron, and transferrin saturation were measured as markers of iron status. A weighted Cox proportional-hazards model was used to estimate crude and multivariate-adjusted hazard ratios for tertiles of different iron parameters in relation to stroke. Results— In a multivariate model, the highest tertile of serum ferritin concentration was associated with an increased risk of stroke (hazard ratio [HR], 1.45; 95% confidence interval [CI], 0.87 to 2.42) compared with the lowest tertile. For ischemic stroke, the increase was more pronounced (HR, 2.23; 95% CI, 1.05 to 4.73) and reached statistical significance. Conclusions— Neither serum iron nor transferrin saturation was associated with an increased stroke risk. However, higher serum ferritin concentrations in postmenopausal women are associated with an increased risk of ischemic stroke.

Non–Transferrin-Bound Iron and Risk of Coronary Heart Disease in Postmenopausal Women

Background— Epidemiological studies aimed at correlating coronary heart disease (CHD) with serum ferritin levels have thus far yielded inconsistent results. We hypothesized that a labile iron component associated with non–transferrin-bound iron (NTBI) that appears in individuals with overt or cryptic iron overload might be more suitable for establishing correlations with CHD. Methods and Results— We investigated the relation of NTBI, serum iron, transferrin saturation, and serum ferritin with risk of CHD and acute myocardial infarction (AMI). The cohort used comprised a population-based sample of 11 471 postmenopausal women aged 49 to 70 years at enrollment in 1993 to 1997. During a median follow-up of 4.3 years (quartile limits Q1 to Q3: 3.3 to 5.4), 185 CHD events were identified, including 66 AMI events. We conducted a case-cohort study using all CHD cases and a random sample from the baseline cohort (n=1134). A weighted Cox proportional hazards model was used to estimate hazard ratios for tertiles of iron variables in relation to CHD and AMI. Adjusted hazard ratios of women in the highest NTBI tertile (range 0.38 to 3.51) compared with the lowest (range −2.06 to −0.32) were 0.84 (95% confidence interval 0.61 to 1.16) for CHD and 0.47 (95% confidence interval 0.31 to 0.71) for AMI. The results were similar for serum iron, transferrin saturation, and serum ferritin. Conclusions— Our results show no excess risk of CHD or AMI within the highest NTBI tertile compared with the lowest but rather seem to demonstrate a decreased risk. Additional studies are warranted to confirm our findings.