Plasma Lp(a) Levels Are Increased in Patients with Chronic Thromboembolic Pulmonary Hypertension

Gender differences in the incidence of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism: A meta-analysis

BACKGROUND

To explore the role of gender in the incidence of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism.

METHODS

Two researchers search the PubMed Database, Embase Database and Cochrane Library Database from their establishment to October 2022, using Endnote software for document management and RevMan5.3 software for the meta-analysis of the included literature. A total of 11 studies are selected, including 5788 acute pulmonary embolism events and 391 patients (179 males and 212 females) with chronic thromboembolic pulmonary hypertension (CTEPH) under the stated conditions. The results show that there is no statistically significant difference in the incidence of CTEPH between males and females after PE (P = .28), with combined OR of 0.89 and 95% CI 0.72-1.10.

RESULTS AND CONCLUSIONS

Gender is found to be absent as a factor in the incidence of CTEPH after acute pulmonary embolism. This may indicate that gender is not a risk factor for CTEPH and that female patients are not necessarily more likely to have a higher incidence than male patients. As such, accurate judgments should be made on the possible complications of all patients after acute pulmonary embolism, which will be conducive to early detection and intervention in the treatment of CTEPH.

Simultaneous quantitation and size characterization of apolipoprotein(a) by ultra-performance liquid chromatography/mass spectrometry

RATIONALE

Apolipoprotein(a) is a polymorphic glycoprotein covalently bound to apoB100 in Lp(a) particles and has been described to be both atherogenic and prothrombotic, although its exact mechanism of action is not well defined. Apolipoprotein(a) is routinely measured by immunoassays. Unfortunately, the accuracy of the measurement can be affected by the apolipoprotein(a) size (number of kringles) polymorphism in Lp(a) particles. Here we describe an ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) assay that is capable of measuring apolipoprotein(a) concentrations while simultaneously determining the number of kringles present per protein.

METHODS

Plasma samples were diluted and proteins de-lipidated with deoxycholate prior to tryptic digestion. Distinct tryptic peptides from different regions of apolipoprotein(a) were measured to determine both concentration and the number of kringles present per protein. Separation and quantitation of tryptic peptides is carried out at 700 μL/min using a 1.7 µm C18 column (2.1 × 100 mm) coupled to a Thermo Vantage triple quadrupole (QQQ) mass spectrometer with a heated electrospray ionization (HESI) source.

RESULTS

This method was compared to established methods for measuring concentration (monoclonal antibody based ELISA) and size (gel-electrophoresis) using 80 plasma samples proved by NWLRL. The slope and r(2) value for the correlation of concentrations were determined to be 0.96 and 0.98, demonstrating excellent agreement of absolute values between the UPLC/MS and ELISA methods. As measured by UPLC/MS, the average kringle number or size is smaller than determined by the electrophoretic method.

CONCLUSIONS

A single UPLC/MS method was developed capable of measuring apolipoprotein(a) concentration and size (by measuring the number of kringles per protein). This assay passes criteria required for 'fit for purpose' assays including sensitivity, intra and interday reproducibility and freeze/thaw stability. While the agreement between UPLC/MS and ELISA is excellent for concentration and may provide researchers with additional tools for studying apolipoprotein(a), the dissimilarities between UPLC/MS and the electrophoretic method may also be exploited for understanding apolipoprotein(a) structure and function.

Chronic thromboembolic pulmonary hypertension (CTEPH): updated Recommendations of the Cologne Consensus Conference 2011

In the 2009 European Guidelines on the diagnosis and treatment of pulmonary hypertension (PH), one section covers aspects of pathophysiology, diagnosis and treatment of chronic thromboembolic pulmonary hypertension (CTEPH). The practical implementation of the guidelines for this disease is of crucial importance, because CTEPH is a subset of PH which can potentially be cured by pulmonary endarterectomy (PEA). Nowadays, CTEPH is commonly underdiagnosed and not properly managed. Any patient with unexplained PH should be evaluated for the presence of CTEPH, and a ventilation/perfusion (V/Q) lung scan is recommended as screening method of choice. If the V/Q scan or CT angiography reveals signs of CTEPH, the patient should be referred to a specialized center with expertise in the medical and surgical management of this disease. Every case has to be reviewed by an experienced PEA surgeon for the assessment of operability. In this updated recommendation, important contents of the European guidelines were commented, and more recent information regarding diagnosis and treatment was added.

Lipoprotein(a) levels, apo(a) isoform size, and coronary heart disease risk in the Framingham Offspring Study

The aim of this study was to assess the independent contributions of plasma levels of lipoprotein(a) (Lp(a)), Lp(a) cholesterol, and of apo(a) isoform size to prospective coronary heart disease (CHD) risk. Plasma Lp(a) and Lp(a) cholesterol levels, and apo(a) isoform size were measured at examination cycle 5 in subjects participating in the Framingham Offspring Study who were free of CHD. After a mean follow-up of 12.3 years, 98 men and 47 women developed new CHD events. In multivariate analysis, the hazard ratio of CHD was approximately two-fold greater in men in the upper tertile of plasma Lp(a) levels, relative to those in the bottom tertile (P < 0.002). The apo(a) isoform size contributed only modestly to the association between Lp(a) and CHD and was not an independent predictor of CHD. In multivariate analysis, Lp(a) cholesterol was not significantly associated with CHD risk in men. In women, no association between Lp(a) and CHD risk was observed. Elevated plasma Lp(a) levels are a significant and independent predictor of CHD risk in men. The assessment of apo(a) isoform size in this cohort does not add significant information about CHD risk. In addition, the cholesterol content in Lp(a) is not a significant predictor of CHD risk.

Serum lipoprotein (a) levels in patients with first unprovoked venous thromboembolism is not associated with subsequent risk of recurrent VTE

INTRODUCTION

Case-control studies suggest that elevated lipoprotein (a) (Lp(a)) is a risk factor for first venous thromboembolism (VTE). Lp(a) has not been prospectively investigated as a possible risk factor for recurrent VTE in first unprovoked VTE patients. We sought to determine if serum Lp(a) levels in patients with unprovoked VTE who discontinue anticoagulants after 5 to 7 months of therapy predict VTE recurrence in a prospective cohort study.

MATERIALS AND METHODS

Serum Lp(a) measurements were obtained from 510 first unprovoked VTE patients treated for 5 -7 months with anticoagulants in a 12 center study. Patients were subsequently followed for a mean of 16.9 months (SD+/-11.2) for symptomatic VTE recurrence which was independently adjudicated with reference to baseline imaging.

RESULTS

There was no significant association between Lp(a) as a continuous variable and recurrent VTE nor in gender stratified subgroups. No statistically significant differences were observed in the median Lp(a) concentrations between patients who recurred and those who did not recur (median (interquartile range): 0.09 g/L (0.17) versus 0.06 g/L (0.11) respectively; p=0.15). The Lp(a) cut-off point of 0.3g/L was not significantly associated with recurrent VTE for the overall population nor in gender stratified subgroups.

CONCLUSIONS

Elevated serum Lp(a) does not appear to be associated with recurrent VTE in patients with history of first unprovoked VTE and may not play a role in identifying patients with unprovoked VTE at high risk of recurrence. There was no optimal predictive threshold for the overall population or for sex sub-groups and Lp(a)>or=0.3 g/L was not a significant predictor of recurrent VTE.

Chronic exposure to fibrin and fibrinogen differentially regulates intracellular Ca2+ in human pulmonary arterial smooth muscle and endothelial cells

Acute pulmonary embolism occurs in more than half a million people a year in the United States. Chronic thromboembolic pulmonary hypertension (CTEPH) develops in approximately 4% of these patients due to unresolved thromboemboli. CTEPH is thus a relatively common, progressive, and potentially fatal disease. One currently proposed theory for the poor resolution advocates that modification of fibrinogen in CTEPH patients causes resistance of emboli to fibrinolysis. The current study investigated the regulation of cytosolic Ca(2+) ([Ca(2+)](cyt)), central to the control of cell migration, proliferation, and contraction, by chronic exposure of pulmonary artery smooth muscle (PASMC) and endothelial (PAEC) cells to fibrinogen and fibrin. Basal [Ca(2+)](cyt) was substantially elevated in PAEC after culture on fibrinogen, fibrin, and thrombin and in PASMC on fibrinogen and fibrin. In PAEC, fibrinogen significantly decreased the peak [Ca(2+)](cyt) transient (P <0.001) without a change in the transient peak width (at 50% of the peak height). This response was independent of effects on the proteinase-activated receptor (PAR) 1. Furthermore, chronic exposure to thrombin, an activator of PAR, significantly reduced the peak agonist-induced Ca(2+) release in PAEC, but increased it in PASMC. The recovery rate of the agonist-induced [Ca(2+)](cyt) transients decelerated in PASMC chronically exposed to fibrin; a small increase of the peak Ca(2+) was also observed. Substantial augmentation of PASMC (but not PAEC) proliferation was observed in response to chronic fibrin exposure. In conclusion, chronic exposure to fibrinogen, fibrin, and thrombin caused differential changes in [Ca(2+)](cyt) in PAEC and PASMC. Such changes in [Ca(2+)](cyt) may contribute to vascular changes in patients who have CTEPH where the pulmonary vasculature is persistently exposed to thromboemboli.

Lipoprotein (a) and venous thromboembolism in adults: a meta-analysis

BACKGROUND

Lipoprotein (a) [Lp(a)], a low-density lipoprotein particle linked to apolipoprotein (a), has been recently demonstrated to be an independent risk factor for arterial vascular diseases. However, despite increasing evidence of the association between high Lp(a) and arterial thrombotic diseases, few and conflicting results on the association between high Lp(a) levels and venous thromboembolism have been obtained. The aim of this article is to systematically examine the published data on the association between high Lp(a) levels and venous thromboembolism.

METHODS

A systematic search of all publications listed in the electronic databases (Medline, EMBASE, Web of Science, and The Cochrane Library) up to November 2006, using keywords in combination both as MeSH terms and text words, was conducted.

RESULTS

Six case-control studies were included, incorporating 1826 cases of venous thromboembolism and 1074 controls. The summary odds ratios of included case-control studies under a fixed-effects model showed a statistically significant association between Lp(a) levels >300 mg/L and venous thromboembolism: 1.87, 95% confidence interval (CI), 1.51-2.30; P <.0001. Furthermore, a random-effects model, which accounts for the interstudy variation, yielded a similar estimate of increased risk (odds ratio [OR] 1.77; 95% CI, 1.14-2.75; P=.01).

CONCLUSIONS

The present meta-analysis shows a significant association between high Lp(a) levels and the occurrence of venous thromboembolism in adults. Indeed, the detection of Lp(a) could be of clinical relevance for venous thromboembolism, especially among patients with absence of traditional and thrombophilic risk factors.

Influence and interaction of diabetes and lipoprotein (a) serum levels on mortality of patients with peripheral artery disease

BACKGROUND

Diabetes mellitus is a risk factor for early complications and mortality in patients with peripheral artery disease. Lipoprotein (a) [Lp(a)] is also suggested to be a marker of increased cardiovascular risk. We investigated the association and interaction between diabetes mellitus, lipoprotein(a) and mortality in high risk patients with peripheral artery disease (PAD).

METHODS

We studied 700 consecutive patients [median age 73 years, interquartile range (IQR) 62-80, 393 male (56%)] with PAD from a registry database. Atherothrombotic risk factors (diabetes, smoking, hyperlipidaemia, arterial hypertension) and Lp(a) serum levels were recorded. We used stratified multivariate Cox proportional hazard analyses to assess the mortality risk at a given patient's age with respect to the presence of diabetes and Lp(a) serum levels (in tertiles).

RESULTS

Patients with Lp(a) levels above 36 mg dL(-1) (highest tertile) and insulin-dependent type II diabetes had a 3.01-fold increased adjusted risk for death (95% confidence interval 1.28-6.64, P = 0.011) compared to patients without diabetes or patients with non-insulin-dependent type II diabetes. In patients with Lp(a) serum levels below 36 mg dL(-1) (lower and middle tertile), diabetes mellitus was not associated with an increased risk for death.

CONCLUSION

Insulin-dependent type II diabetes mellitus seems to be associated with an increased risk for mortality in PAD patients with Lp(a) serum levels above 36 mg dL(-1). PAD patients with non-insulin-dependent type II diabetes, and patients with diabetes and Lp(a) levels below 36 mg dL(-1) showed survival rates comparable to PAD patients without diabetes.

Lipoprotein (a) in patients with spontaneous venous thromboembolism

INTRODUCTION

Elevated lipoprotein (a) (Lp (a)) has been established as a risk factor of coronary heart disease and stroke. Findings concerning the risk of venous thromboembolism (VTE) in adults are contradictory. The aim of our study was to investigate, whether elevated Lp (a) levels are an independent risk factor of spontaneous symptomatic venous thromboembolism (VTE). Our study was further designed to detect differences in risk profiles between thrombosis patients with and without symptomatic PE.

MATERIALS AND METHODS

We investigated Lp (a) in 128 patients with spontaneous symptomatic deep vein thrombosis (DVT, group 1), 105 with spontaneous symptomatic pulmonary embolism with or without DVT (PE, group 2) and 122 healthy controls. Lp (a) was measured with an immunoturbidimetric assay (Tina-quant(R), Roche, Grenzach-Wyhlen, Germany) on a Hitachi-Modular system.

RESULTS

Lp (a) levels (mg/L) were not significantly different among groups, median levels (25th-75th percentiles) were 170 (51-386) in group 1, 140 (<20-427) in group 2 and 126 (54-331) in controls, respectively. As continuous variable, odds ratios for VTE for a 100 mg/L increase of Lp (a) were 1.1 [95% confidence interval 0.98-1.2] for group 1 versus controls and 1.1 [0.95-1.2] for group 2 versus controls. The prevalence of Lp (a) above 300 mg/L was not significantly different among patients and controls (group 1: 30%, group 2: 32% and controls: 25%, p=0.4, p=0.2, respectively).

CONCLUSIONS

In conclusion we found no association between Lp (a) and VTE regardless whether DVT occurred together with PE or not.

Quo vadis haemapheresis. Current developments in haemapheresis

The techniques of haemapheresis originated in the development of centrifugal devices separating cells from plasma and later on plasma from cells. Subsequently membrane filtration was developed allowing for plasma-cell separation. The unspecificity of therapeutic plasma exchange led to the development of secondary plasma separation technologies being specific, semi-selective or selective such as adsorption, filtration or precipitation. In contrast on-line differential separation of cells is still under development. Whereas erythrocytapheresis, granulocytapheresis, lymphocytapheresis and stem cell apheresis are technically advanced, monocytapheresis may need further improvement. Also, indications such as erythrocytapheresis for the treatment of polycythaemia vera or photopheresis though being clinically effective and of considerable importance for an appropriate disease control are to some extent under debate as being either too costly or without sufficient understanding of the mechanism. Other forms of cell therapy are under development. Rheohaemapheresis as the most advanced technology of extracorporeal haemorheotherapy is a rapidly developing approach contributing to the treatment of microcirculatory diseases and tissue repair. Whereas the control of a considerable number of (auto-) antibody mediated diseases is beyond discussion, the indication of apheresis therapy for immune complex mediated diseases is quite often still under debate. Detoxification for artificial liver support advanced considerably during the last years, whereas conclusions on the efficacy of septicaemia treatment are debatable indeed. LDL-apheresis initiated in 1981 as immune apheresis is well established since 24 years, other semi-selective or unspecific procedures, allowing for the elimination of LDL-cholesterol among other plasma components are also being used. Correspondingly Lp(a) apheresis is available as a specific, highly efficient elimination procedure superior to techniques which also eliminate Lp(a). Quality control systems, more economical technologies as for instance by increasing automation, influencing the over-interpretation of evidence based medicine especially in patients with rare diseases without treatment alternative, more insight into the need of controlled clinical trials or alternatively improved diagnostic procedures are among others tools ways to expand the application of haemapheresis so far applied in cardiology, dermatology, haematology, immunology, nephrology, neurology, ophthalmology, otology, paediatrics, rheumatology, surgery and transfusion medicine.

Dyslipidemia, statins, and venous thromboembolism: a potential risk factor and a potential treatment

The optimal drug for the prevention of venous thromboembolism is one that is efficacious, associated with minimal bleeding risk, and easy to administer. Statins fulfill the latter two criteria, but their efficacy remains unproved. By examining the association between dyslipidemia and venous thromboembolism, as well as the evidence that statins might prevent venous thromboembolism, there may be a new rationale for the use of this class of drugs. There may be a common link between arterial and venous thrombosis. Dyslipidemia may be one of the many systemic factors associated not only with arterial thrombosis, but with venous thromboembolism as well. This may occur through the effects of circulating lipid molecules on the vascular endothelium, platelet function, and coagulation factors. By impeding these mechanisms, statins may be protective against venous thrombosis, but epidemiologic studies are few in number, and no randomized clinical trials have been conducted. Better epidemiologic evidence is required to establish whether dyslipidemia is a risk factor for venous thromboembolism. If future observational studies can demonstrate that statins are associated with a lower risk of venous thromboembolism, then consideration should be given to conducting a randomized clinical trial comparing statins with placebo for the prevention of venous thromboembolism. Until then, the efficacy of statins for the prevention or treatment of venous thromboembolism remains uncertain.

Evaluation of lipoprotein(a) as a prothrombotic factor: progress from bench to bedside

PURPOSE OF REVIEW

Since the homology between apolipoprotein(a) (apo(a)) and plasminogen was discovered in 1987, the role of lipoprotein(a) (Lp(a)) as an inhibitor of the normal fibrinolytic role of plasmin(ogen) has been a major research focus. In this review we summarize recent basic research aimed at identifying mechanisms by which Lp(a) can either inhibit fibrinolysis or promote coagulation, as well as recent clinical studies of Lp(a) as a risk factor for thrombosis either in the presence or absence of atherosclerosis.

RECENT FINDINGS

It has recently been reported that the inhibition of plasminogen activation by apo(a) results from the interaction of apo(a) with the ternary complex of tissue-type plasminogen activator, plasminogen and fibrin, rather than competition of apo(a) and plasminogen for binding sites on fibrin. Lp(a) species containing smaller apo(a) isoforms bind more avidly to fibrin and are better inhibitors of plasminogen activation. Recent clinical studies have provided strong evidence that Lp(a), either alone or in synergy with other thrombotic risk factors, significantly increases the risk of venous thromboembolism and ischemic stroke.

SUMMARY

Lp(a) both attenuates fibrinolysis, through inhibition of plasminogen activation, and promotes coagulation, through alleviation of extrinsic pathway inhibition. Further basic and clinical studies are required to more clearly define the role of Lp(a) in thrombotic disorders, and to determine the extent to which thrombotic risk is dependent on apo(a) isoform size.

Lipoprotein(a): an emerging cardiovascular risk factor

Lipoprotein(a) is a cholesterol-enriched lipoprotein, consisting of a covalent linkage joining the unique and highly polymorphic apolipoprotein(a) to apolipoprotein B100, the main protein moiety of low-density lipoproteins. Although the concentration of lipoprotein(a) in humans is mostly genetically determined, acquired disorders might influence synthesis and catabolism of the particle. Raised concentration of lipoprotein(a) has been acknowledged as a leading inherited risk factor for both premature and advanced atherosclerosis at different vascular sites. The strong structural homologies with plasminogen and low-density lipoproteins suggest that lipoprotein(a) might represent the ideal bridge between the fields of atherosclerosis and thrombosis in the pathogenesis of vascular occlusive disorders. Unfortunately, the exact mechanisms by which lipoprotein(a) promotes, accelerates, and complicates atherosclerosis are only partially understood. In some clinical settings, such as in patients at exceptionally low risk for cardiovascular disease, the potential regenerative and antineoplastic properties of lipoprotein(a) might paradoxically counterbalance its athero-thrombogenicity, as attested by the compatibility between raised plasma lipoprotein(a) levels and longevity.

Why might statins prevent venous thromboembolism: what needs to be done to know more?

Dyslipidaemia may be a risk factor for venous thromboembolism and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may be protective. The current review outlines the cumulative evidence from both the basic and epidemiologic sciences for why this might be so and offers some directions for future research.

Serum lipoprotein(a) and its relation to left ventricular thrombus in patients with acute myocardial infarction

It is well known that the incidence of left ventricular (LV) thrombosis is high in patients with acute myocardial infarction (AMI). Due to the high degree of structural homology with plasminogen, lipoprotein(a) may produce thrombogenic effects by modulating the fibrinolytic system. However, the role of Lp(a) level in the formation of LV thrombus has not been studied. This study sought to determine whether Lp(a) is a risk factor for LV thrombus in patients with AMI. We have analyzed clinical, echocardiographic and biochemical data in 102 consecutive patients (aged 58+/-12 years, 92 men / 10 women) with first anterior AMI. Two-dimensional examination was performed on days 1, 3, 7, 15, and 30. Blood samples were obtained within 12 h after the onset of symptoms and before beginning the therapy. Plasma levels of fibrinogen and Lp(a) were measured using enzyme-linked immunosorbent assay and immunonephelometric methods, respectively. LV thrombus was detected in 20 (20.3%) patients. No significant difference was found for admission Lp(a) levels between patients with or without thrombus (30.5+/-17.2 vs 32.3+/-22.4 mg/dl, p = 0.7). Univariate analysis showed that patients with LV thrombus had a higher wall motion score index (1.8+/-0.3 vs 1.4+/-0.3, p = 0.002), a higher peak creatine kinase level (2945+/-898 vs 1805+/-1336, I / U p = 0.004), a larger end-diastolic volume (139.7+/-38.6 vs 114.1+/-41.8 ml, p = 0.04), a larger end-systolic volume (83.1+/-34.3 vs 59.2+/-30.6 ml, p = 0.02 ), and a lower ejection fraction (38+/-12 vs 47+/-11, p = 0.04). In multivariate analyses, only peak creatine kinase level (p = 0.04) and LV wall motion score index (p = 0.002) were independent predictors of left ventricular thrombus formation. These results suggest that Lp (a) is not a risk factor for LV thrombus in patients with AMI. Our data demonstrate that the best predictors of LV thrombus formation after AMI are a high peak creatine kinase level and a high LV wall motion score index.

Increased lipoprotein (a) levels as an independent risk factor for venous thromboembolism

Elevation of serum lipoprotein (a) (Lp[a]) is a known risk factor predisposing to cardiovascular and cerebrovascular disease. However, little is known about the role of increased Lp(a) in venous thromboembolism (VTE). This study evaluated the role of Lp(a) among a panel of established hereditary thrombogenic defects in patients with VTE. A total of 685 consecutive patients with at least one episode of VTE and 266 sex- and age-matched healthy controls were screened with regard to activated protein C resistance, protein C, protein S, and antithrombin deficiency, elevated serum levels of Lp(a), and the factor V G1691A, MTHFR C677T, and prothrombin G20210A mutations. Elevated Lp(a) levels above 30 mg/dL were found in 20% of all patients, as compared to 7% among healthy controls (P < .001, odds ratio [OR] 3.2, 95% confidence interval [CI], 1.9-5.3). The coexistence of FV G1691A and elevated Lp(a) was significantly more prevalent among patients with VTE than in the control group (7% versus 0.8%; P < .001, OR 9.8, 95% CI, 2.4-40.7). No other established prothrombotic risk factor was found to be significantly combined with increased Lp(a). These data suggest that Lp(a) concentrations greater than 30 mg/dL are a frequent and independent risk factor for VTE. Furthermore, elevated Lp(a) levels might contribute to the penetrance of thromboembolic disease in subjects being affected by other prothrombotic defects, such as FV G1691A mutation.

Increased lipoprotein (a) levels as an independent risk factor for venous thromboembolism

Elevation of serum lipoprotein (a) (Lp[a]) is a known risk factor predisposing to cardiovascular and cerebrovascular disease. However, little is known about the role of increased Lp(a) in venous thromboembolism (VTE). This study evaluated the role of Lp(a) among a panel of established hereditary thrombogenic defects in patients with VTE. A total of 685 consecutive patients with at least one episode of VTE and 266 sex- and age-matched healthy controls were screened with regard to activated protein C resistance, protein C, protein S, and antithrombin deficiency, elevated serum levels of Lp(a), and the factor V G1691A, MTHFR C677T, and prothrombin G20210A mutations. Elevated Lp(a) levels above 30 mg/dL were found in 20% of all patients, as compared to 7% among healthy controls (P &lt; .001, odds ratio [OR] 3.2, 95% confidence interval [CI], 1.9-5.3). The coexistence of FV G1691A and elevated Lp(a) was significantly more prevalent among patients with VTE than in the control group (7% versus 0.8%; P &lt; .001, OR 9.8, 95% CI, 2.4-40.7). No other established prothrombotic risk factor was found to be significantly combined with increased Lp(a). These data suggest that Lp(a) concentrations greater than 30 mg/dL are a frequent and independent risk factor for VTE. Furthermore, elevated Lp(a) levels might contribute to the penetrance of thromboembolic disease in subjects being affected by other prothrombotic defects, such as FV G1691A mutation.