Relation of serum homocysteine and lipoprotein(a) concentrations to atherosclerotic disease in a prospective Finnish population based study

Consensus document on Lipoprotein(a) from the Italian Society for the Study of Atherosclerosis (SISA)

AIMS

In view of the consolidating evidence on the causal role of Lp(a) in cardiovascular disease, the Italian Society for the Study of Atherosclerosis (SISA) has assembled a consensus on Lp(a) genetics and epidemiology, together with recommendations for its measurement and current and emerging therapeutic approaches to reduce its plasma levels. Data on the Italian population are also provided.

DATA SYNTHESIS

Lp(a) is constituted by one apo(a) molecule and a lipoprotein closely resembling to a low-density lipoprotein (LDL). Its similarity with an LDL, together with its ability to carry oxidized phospholipids are considered the two main features making Lp(a) harmful for cardiovascular health. Plasma Lp(a) concentrations vary over about 1000 folds in humans and are genetically determined, thus they are quite stable in any individual. Mendelian Randomization studies have suggested a causal role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis and observational studies indicate a linear direct correlation between cardiovascular disease and Lp(a) plasma levels. Lp(a) measurement is strongly recommended once in a patient's lifetime, particularly in FH subjects, but also as part of the initial lipid screening to assess cardiovascular risk. The apo(a) size polymorphism represents a challenge for Lp(a) measurement in plasma, but new strategies are overcoming these difficulties. A reduction of Lp(a) levels can be currently attained only by plasma apheresis and, moderately, with PCSK9 inhibitor treatment.

CONCLUSIONS

Awaiting the approval of selective Lp(a)-lowering drugs, an intensive management of the other risk factors for individuals with elevated Lp(a) levels is strongly recommended.

Lipoprotein(a) as a Risk Factor for Cardiovascular Diseases: Pathophysiology and Treatment Perspectives

Cardiovascular disease (CVD) is still a leading cause of morbidity and mortality, despite all the progress achieved as regards to both prevention and treatment. Having high levels of lipoprotein(a) [Lp(a)] is a risk factor for cardiovascular disease that operates independently. It can increase the risk of developing cardiovascular disease even when LDL cholesterol (LDL-C) levels are within the recommended range, which is referred to as residual cardiovascular risk. Lp(a) is an LDL-like particle present in human plasma, in which a large plasminogen-like glycoprotein, apolipoprotein(a) [Apo(a)], is covalently bound to Apo B100 via one disulfide bridge. Apo(a) contains one plasminogen-like kringle V structure, a variable number of plasminogen-like kringle IV structures (types 1-10), and one inactive protease region. There is a large inter-individual variation of plasma concentrations of Lp(a), mainly ascribable to genetic variants in the Lp(a) gene: in the general po-pulation, Lp(a) levels can range from <1 mg/dL to >1000 mg/dL. Concentrations also vary between different ethnicities. Lp(a) has been established as one of the risk factors that play an important role in the development of atherosclerotic plaque. Indeed, high concentrations of Lp(a) have been related to a greater risk of ischemic CVD, aortic valve stenosis, and heart failure. The threshold value has been set at 50 mg/dL, but the risk may increase already at levels above 30 mg/dL. Although there is a well-established and strong link between high Lp(a) levels and coronary as well as cerebrovascular disease, the evidence regarding incident peripheral arterial disease and carotid atherosclerosis is not as conclusive. Because lifestyle changes and standard lipid-lowering treatments, such as statins, niacin, and cholesteryl ester transfer protein inhibitors, are not highly effective in reducing Lp(a) levels, there is increased interest in developing new drugs that can address this issue. PCSK9 inhibitors seem to be capable of reducing Lp(a) levels by 25-30%. Mipomersen decreases Lp(a) levels by 25-40%, but its use is burdened with important side effects. At the current time, the most effective and tolerated treatment for patients with a high Lp(a) plasma level is apheresis, while antisense oligonucleotides, small interfering RNAs, and microRNAs, which reduce Lp(a) levels by targeting RNA molecules and regulating gene expression as well as protein production levels, are the most widely explored and promising perspectives. The aim of this review is to provide an update on the current state of the art with regard to Lp(a) pathophysiological mechanisms, focusing on the most effective strategies for lowering Lp(a), including new emerging alternative therapies. The purpose of this manuscript is to improve the management of hyperlipoproteinemia(a) in order to achieve better control of the residual cardiovascular risk, which remains unacceptably high.

Lipoprotein(a): Just an Innocent Bystander in Arterial Hypertension?

Elevated plasma lipoprotein(a) [Lp(a)] is a relatively common and highly heritable trait conferring individuals time-dependent risk of developing atherosclerotic cardiovascular disease (CVD). Following its first description, Lp(a) triggered enormous scientific interest in the late 1980s, subsequently dampened in the mid-1990s by controversial findings of some prospective studies. It was only in the last decade that a large body of evidence has provided strong arguments for a causal and independent association between elevated Lp(a) levels and CVD, causing renewed interest in this lipoprotein as an emerging risk factor with a likely contribution to cardiovascular residual risk. Accordingly, the 2022 consensus statement of the European Atherosclerosis Society has suggested inclusion of Lp(a) measurement in global risk estimation. The development of highly effective Lp(a)-lowering drugs (e.g., antisense oligonucleotides and small interfering RNA, both blocking LPA gene expression) which are still under assessment in phase 3 trials, will provide a unique opportunity to reduce "residual cardiovascular risk" in high-risk populations, including patients with arterial hypertension. The current evidence in support of a specific role of Lp(a) in hypertension is somehow controversial and this narrative review aims to overview the general mechanisms relating Lp(a) to blood pressure regulation and hypertension-related cardiovascular and renal damage.

Homocysteine, Vitamins B6, B12, and Folate and the Risk of Ischemic and Hemorrhagic Stroke: A Case-control Study from Northeast India

Background

Stroke is a major leading global health complication. Identification and management of risk factors associated with stroke can help in prior detection, prevention, and improvement in patient care.

Purpose

To investigate the prevalence of hyperhomocysteinemia (HHcy) and Vitamins B6, B12, and folate deficiency in stroke patients and also to assess other risk factors associated with ischemic and hemorrhagic stroke.

Methods

Detail history of all the subjects in the study including history of hypertension, anemia, fasting glucose, carotid artery thickness, smoking, alcohol, and dietary intake was recorded. Standard assays for homocysteine (Hcy), Vitamins B6, B12, and folate estimation were done. Lipid and renal profile tests were also performed. The prevalence and odds of having HHcy, Vitamins B6, B12, and folate deficiency, and other risk factors in ischemic and hemorrhagic stroke patients were evaluated. Student’s t-tests and chi-square tests were done for statistical validation of the data.

Results

Prevalence of HHcy and Vitamins B6, B12, and folate deficiency was not observed in ischemic cases. HHcy and folate deficiency was found to be prevalent in hemorrhagic stroke patients. The odds that a person with HHcy and folate deficiency has hemorrhagic stroke was found to be significantly high.

Conclusion

In our study, high Hcy and low folate levels emerged as risk factors for hemorrhagic stroke.

Impact of Lipoprotein(a) concentrations on long-term cardiovascular outcomes in patients undergoing percutaneous coronary intervention: A large cohort study

BACKGROUND AND AIMS

Till now, the prognostic value of lipoprotein(a) [Lp(a)] in patients with coronary artery disease (CAD) who underwent percutaneous coronary intervention (PCI) remains controversial. We therefore conducted this study to evaluate the effect of Lp(a) levels on clinical outcomes in this population.

METHODS AND RESULTS

A total of 10,059 CAD patients who underwent PCI were prospectively enrolled in this cohort study, of which 6564 patients had Lp(a) ≤30 mg/dl and 3495 patients had Lp(a) > 30 mg/dl. The primary endpoint was major adverse cardiovascular and cerebrovascular event (MACCE), defined as a composite of all-cause death, myocardial infarction, stroke or unplanned revascularization. Multivariate Cox regression analysis and propensity-score matching analysis were performed. After propensity-score matching, 3449 pairs of patients were identified, and post-matching absolute standardized differences were <10% for all the covariates. At 2.4 years, the risk of MACCE was significantly higher in patients with elevated Lp(a) levels than those with normal Lp(a) levels in both overall population (13.0% vs. 11.4%; adjusted hazard ratio [HR] 1.142, 95% confidence interval [CI] 1.009-1.293; P = 0.040) and propensity-matched cohorts (13.0% vs. 11.2%; HR 1.167, 95%CI 1.019-1.337; P = 0.026). Of note, the predictive value of Lp(a) levels on MACCE tended to be more evident in individuals >65 years or those with left main and/or three-vessel disease. On the contrary, elevated Lp(a) levels had almost no effect on clinical outcomes in patients ≤65 years (P _interaction = 0.021) as well as those who had one- or two-vessel coronary artery disease (P _interaction = 0.086).

CONCLUSION

In CAD patients who underwent PCI, elevated Lp(a) levels were positively related to higher risk of MACCE at 2.4-year follow-up, especially in patients >65 years and those with left main and/or three-vessel disease.

REGISTRATION NUMBER

not applicable.

Machine Learning-Based Model for Prediction of Hemorrhage Transformation in Acute Ischemic Stroke After Alteplase

Hemorrhage transformation (HT) is the most dreaded complication of intravenous thrombolysis (IVT) in acute ischemic stroke (AIS). The prediction of HT after IVT is important in the treatment decision-making for AIS. We designed and compared different machine learning methods, capable of predicting HT in AIS after IVT. A total of 345 AIS patients who received intravenous alteplase between January 2016 and June 2021 were enrolled in this retrospective study. The demographic characteristics, clinical condition, biochemical data, and neuroimaging variables were included for analysis. HT was confirmed by head computed tomography (CT) or magnetic resonance imaging (MRI) within 48 h after IVT. Based on the neuroimaging results, all of the patients were divided into the non-HT group and the HT group. Then, the variables were applied in logistic regression (LR) and random forest (RF) algorithms to establish HT prediction models. To evaluate the accuracy of the machine learning models, the models were compared to several of the common scales used in clinics, including the multicenter stroke survey (MSS) score, safe implementation of treatments in stroke (SITS) score, and SEDAN score. The performance of these prediction models was evaluated using the receiver operating characteristic (ROC) curve (AUC). Forty-five patients had HT (13.0%) within 48 h after IVT. The ROC curve results showed that the AUCs of HT that were predicted by the RF model, LR model, MSS, SITS, and SEDAN scales after IVT were 0.795 (95% CI, 0.647–0.944), 0.703 (95% CI, 0.515–0.892), 0.657 (95% CI, 0.574–0.741), 0.660 (95% CI, 0.580–0.740) and 0.655 (95% CI, 0.571–0.739), respectively. The RF model performed better than the other models and scales. The top four most influential factors in the RF importance matrix plot were triglyceride, Lpa, the baseline NIHSS, and hemoglobin. The SHapley Additive exPlanation values made the RF prediction model clinically interpretable. In this study, an RF machine learning method was successfully established to predict HT in AIS patients after intravenous alteplase, which the sensitivity was 66.7%, and the specificity was 80.7%.

Lipoprotein(a) and cardiovascular and valvular diseases: A genetic epidemiological perspective

Rates of atherosclerotic cardiovascular diseases (CVD) in the Western world have spectacularly decreased over the past 50 years. However, a substantial proportion of high-risk patients still develop heart attacks, strokes and valvular heart diseases despite benefiting from state-of-the-art treatments including lipid-lowering therapies. Over the past 10-15 years, it has become increasingly clear that Lipoprotein(a) (Lp[a]) is a critical component of this so-called residual risk. Genetic association studies revealed that Lp(a) is robustly, independently and causally associated with a broad range of cardiovascular and valvular heart diseases. Up to 1 billion people around the globe may have an Lp(a) level that places them in a high-risk category. Lp(a) is strongly associated with calcific aortic valve stenosis (CAVS), coronary artery disease (CAD), peripheral arterial disease (PAD) and to a lesser extent with ischemic stroke (IS) and heart failure (HF). Because of this strong association with cardiovascular and valvular heart diseases, Lp(a) even emerged as one of the most important genetic determinants of human lifespan and healthspan. Here, we review the evidence from the largest and most informative genetic association studies and prospective studies that have investigated the association between Lp(a) and human lifespan, healthspan, CVD, CAVS and non-cardiovascular diseases. We present Lp(a) threshold values that may be clinically relevant and identify other cardiovascular risk factors that may modulate the absolute risk of CVD in individuals with high Lp(a) levels. Finally, we identify key clinical and research questions that require further investigation to eventually and optimally reduce CVD risk in patients with high Lp(a) levels.

Lipoprotein (a) level as a risk factor for stroke and its subtype: A systematic review and meta-analysis

The role of lipoprotein-A [Lp (a)] as a risk factor for stroke is less well documented than for coronary heart disease. Hence, we conducted a systematic review and meta-analysis for the published observational studies in order to investigate the association of Lp (a) levels with the risk of stroke and its subtypes. In our meta-analysis, 41 studies involving 7874 ischemic stroke (IS) patients and 32,138 controls; 13 studies for the IS subtypes based on TOAST classification and 7 studies with 871 Intracerebral hemorrhage (ICH) cases and 2865 control subjects were included. A significant association between increased levels of Lp (a) and risk of IS as compared to control subjects was observed (standardized mean difference (SMD) 0.76; 95% confidence interval (CIs) 0.53-0.99). Lp (a) levels were also found to be significantly associated with the risk of large artery atherosclerosis (LAA) subtype of IS (SMD 0.68; 95% CI 0.01-1.34) as well as significantly associated with the risk of ICH (SMD 0.65; 95% CI 0.13-1.17) as compared to controls. Increased Lp (a) levels could be considered as a predictive marker for identifying individuals who are at risk of developing IS, LAA and ICH.

Lipoprotein(a) and Cardiovascular Disease

BACKGROUND

High lipoprotein(a) concentrations present in 10%-20% of the population have long been linked to increased risk of ischemic cardiovascular disease. It is unclear whether high concentrations represent an unmet medical need. Lipoprotein(a) is currently not a target for treatment to prevent cardiovascular disease.

CONTENT

The present review summarizes evidence of causality for high lipoprotein(a) concentrations gained from large genetic epidemiologic studies and discusses measurements of lipoprotein(a) and future treatment options for high values found in an estimated >1 billion individuals worldwide.

SUMMARY

Evidence from mechanistic, observational, and genetic studies support a causal role of lipoprotein(a) in the development of cardiovascular disease, including coronary heart disease and peripheral arterial disease, as well as aortic valve stenosis, and likely also ischemic stroke. Effect sizes are most pronounced for myocardial infarction, peripheral arterial disease, and aortic valve stenosis where high lipoprotein(a) concentrations predict 2- to 3-fold increases in risk. Lipoprotein(a) measurements should be performed using well-validated assays with traceability to a recognized calibrator to ensure common cut-offs for high concentrations and risk assessment. Randomized cardiovascular outcome trials are needed to provide final evidence of causality and to assess the potential clinical benefit of novel, potent lipoprotein(a) lowering therapies.

Hyperhomocysteinemia and Ischemic Stroke: A Potential Dose-Response Association-A Systematic Review and Meta-analysis

Background and Purpose  Previous studies suggest an association between increased homocysteine (Hcy) and risk of ischemic stroke. Yet, it remains unknown whether a dose-response association exists between Hcy levels and risk of ischemic stroke. Methods  Systematic literature searches were performed in PubMed, Embase, Scopus, and Web of Science. Inclusion criteria were studies investigating ischemic stroke risk in an adult population with measured Hcy levels. We computed odds ratios (ORs) for a 5 µmol/L increase in Hcy levels using a random effects meta-analysis. Results  In total, 108 studies met the inclusion criteria of which 22 were rated as high-quality studies, and 20 studies included a dose-response analysis. Hcy levels were analyzed either as a continuous or categorical variable. The majority of the studies found an increased risk of ischemic stroke when comparing the highest-to-lowest Hcy strata. A graded association was observed over the Hcy strata, indicating a dose-response association, with the most apparent effect when Hcy levels exceeded approximately 15 µmol/L. No studies explored a potential nonlinear association between Hcy levels and ischemic stroke. Six studies were included in a meta-analysis, showing an OR of 1.43 (95% confidence interval [CI]: 1.28-1.61) per 5 µmol/L increase in Hcy levels. Conclusion  This review and meta-analysis indicate a dose-response association between Hcy levels and ischemic stroke. An evident increase in effect measures was observed when Hcy levels exceeded 15 µmol/L, indicating a nonlinear association between ischemic stroke and Hcy levels. This nonlinear association warrants further study. This study is registered with clinical trial ( https://www.crd.york.ac.uk/prospero/ ; unique identifier: CRD42019130371).

Lipids and Lipid Mediators Associated with the Risk and Pathology of Ischemic Stroke

Stroke is a severe neurological disorder in humans that results from an interruption of the blood supply to the brain. Worldwide, stoke affects over 100 million people each year and is the second largest contributor to disability. Dyslipidemia is a modifiable risk factor for stroke that is associated with an increased risk of the disease. Traditional and non-traditional lipid measures are proposed as biomarkers for the better detection of subclinical disease. In the central nervous system, lipids and lipid mediators are essential to sustain the normal brain tissue structure and function. Pathways leading to post-stroke brain deterioration include the metabolism of polyunsaturated fatty acids. A variety of lipid mediators are generated from fatty acids and these molecules may have either neuroprotective or neurodegenerative effects on the post-stroke brain tissue; therefore, they largely contribute to the outcome and recovery from stroke. In this review, we provide an overview of serum lipids associated with the risk of ischemic stroke. We also discuss the role of lipid mediators, with particular emphasis on eicosanoids, in the pathology of ischemic stroke. Finally, we summarize the latest research on potential targets in lipid metabolic pathways for ischemic stroke treatment and on the development of new stroke risk biomarkers for use in clinical practice.

Correlation Between Hyperhomocysteinemia and Outcomes of Patients With Acute Myocardial Infarction

Overwhelming clinical and epidemiological studies have identified elevated plasma total homocysteine (Hcy) as new important risk factor for atherosclerotic vascular disease. But the relationship between outcome and hyperhomocysteinemia in patients with acute myocardial infarction (AMI) has been rarely reported. This study aimed to evaluate the association between hyperhomocysteinemia and short-term outcomes of patients with AMI. Eight hundred five patients were divided into high Hcy level group (group H: N = 457) and low Hcy level group (group L: N = 348) according to the plasma Hcy levels of 15 mmol/L. The comparisons were made between 2 groups in the following aspects: sex, hypertension, diabetes, hyperlipidemia, the time for symptom from onset to percutaneous coronary intervention, homoccyteine, creatine phosphokinase isoenzyme (creatine kinase myocardial band), and the incidence of 30-day adverse events. The incidences of heart failure, cardiac rupture, death, and the total adverse cardiovascular events were statistically significantly higher in group H than in group L. But the incidence of postoperative angina pectoris and reinfarction was similar between groups. The results of logistic regression showed that the incidence of 30-day adverse events was closely related to the age and the level of Hcy. An elevated plasma total Hcy level in patients with AMI experienced pemutaneous coronary intervention may be related to the short-term outcomes. An elevated high plasma Hcy level also seems to be an independent predictor of 30-day cardiovascular events in patients with AMI.

Lipoprotein (a) as a cause of cardiovascular disease: insights from epidemiology, genetics, and biology

Human epidemiologic and genetic evidence using the Mendelian randomization approach in large-scale studies now strongly supports that elevated lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular disease, that is, for myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis. The Mendelian randomization approach used to infer causality is generally not affected by confounding and reverse causation, the major problems of observational epidemiology. This approach is particularly valuable to study causality of Lp(a), as single genetic variants exist that explain 27-28% of all variation in plasma Lp(a). The most important genetic variant likely is the kringle IV type 2 (KIV-2) copy number variant, as the apo(a) product of this variant influences fibrinolysis and thereby thrombosis, as opposed to the Lp(a) particle per se. We speculate that the physiological role of KIV-2 in Lp(a) could be through wound healing during childbirth, infections, and injury, a role that, in addition, could lead to more blood clots promoting stenosis of arteries and the aortic valve, and myocardial infarction. Randomized placebo-controlled trials of Lp(a) reduction in individuals with very high concentrations to reduce cardiovascular disease are awaited. Recent genetic evidence documents elevated Lp(a) as a cause of myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis.

Homocysteine Level and Coronary Artery Disease

Atherosclerosis, and its most common manifestation, coronary artery disease (CAD), are rather common causes of morbidity and mortality worldwide. Recognition of its various risk factors is important to planning effective preventive measures. After the homocysteine theory was presented in 1969, attention has been directed toward the serum homocysteine level as a coronary artery disease risk factor. The authors aimed to assess the relationship between hyperhomocysteinemia and CAD in an Iranian population. In a case control study, 197 individuals (male: 123 [62.4%]) who were scheduled for coronary angiography were selected. Venous samples were taken from the patients in fasting state before angiography. Data about age, sex, risk factors (eg, hypertension, diabetes, smoking, hyperlipidemia, obesity) were obtained from prepared questionnaires. Homocysteine levels in patients were measured by ELISA method. A homocysteine level above 15 µmol/liter was considered high. Angiography reports and homocysteine levels were analyzed by independent sample t test, one-way ANOVA, multiple linear regression, and stratified analysis. In comparison with the patients with normal angiography reports (32.5%), patients with abnormal angiography reports (67.5%) had increased levels of homocysteine (p=0.001). About 28.1% of patients with normal angiography reports had hyperhomocysteinemia. After further evaluation, linear correlations were detected between the numbers of involved vessels and homocysteine level (p=0.000). Multiple linear regression analysis of data detected that in individuals without any risk factors, the relationship was stronger and more meaningful (p=0.000). These data show that hyperhomocysteinemia is related to CAD as an independent risk factor. In individuals without any risk factors a linear correlation between homocysteine level and numbers of coronary artery involvement was present. If this equation is confirmed prospectively in other studies, the level of plasma homocysteine may he used as a noninvasive way of predicting the number of diseased coronary arteries.

Fractions of Total Plasma Homocysteine in Patients with Ischemic Stroke Before the Age of 55 Years

The mechanism responsible for the association between elevated circulating homocysteine levels and ischemic stroke remains unclear. Therefore, the authors assessed total plasma homocysteine (tHcy) and its fractions (free [fHcy] and protein-bound [bHcy] homocysteine) in patients with ischemic stroke before the age of 55 years. Fifty patients (23 men, mean age 46.8 ±7.6 years) with ischemic stroke or transient ischemic attacks, with symptoms lasting <72 hours were enrolled. In this group: 32 (64%) patients had hypertension; 12 (24%), ischemic heart disease (IHD); and 20 (40%), type 2 diabetes mellitus (DM). The control group consisted of 30 matched healthy individuals (17 men, mean age 44.6 ±6.2 years). The tHcy, fHcy, and bHcy levels were determined by high-performance liquid chromatography. tHcy and its fractions did not differ significantly between patients and controls. However, stroke patients with hypertension had significantly higher concentrations of tHcy and bHcy compared to stroke patients without hypertension (tHcy 13.0 ±3.3 vs 10.7 ±3.2 µmol/L, p<0.05; bHcy 9.7 ±2.6 vs 7.8 ±2.3 µmol/L, p<0.01, respectively); fHcy was borderline significant: 3.1 (1.5-6.5) vs 2.5 (1.8-5.3) µmol/L, p=0.05. The presence of IHD, DM, hyperlipoproteinemia, clinical subtypes of stroke, smoking, and family history of stroke did not influence these parameters. In the group of 50 patients, tHcy correlated with mean systolic blood pressure (BP) ( r =0.3, p<0.05) and bHcy correlated with mean systolic and mean diastolic BP ( r =0.3, p<0.05). These findings suggest an association between hypertension and redox status of Hcy in patients with ischemic stroke before the age of 55 years. This observation supports the hypothesis that elevated BP may contribute to Hcy-related vascular injury.

Design and statistical issues in the homocysteinemia in kidney and end stage renal disease (HOST) study

The Homocysteine Study (HOST) Veterans Affairs Cooperative Studies Program No. 453, is a prospective, randomized, two arm, double blind study of patients with end stage renal disease (ESRD) or advanced chronic kidney disease (ACKD, defined as an estimated creatinine clearance of 30 ml/min or less). Its primary objective is to determine whether administration of high doses of three vitamins, folic acid, vitamin B6 and vitamin B12, to lower the high plasma homocysteine levels, will reduce all cause mortality. The secondary objectives are to examine whether the treatment lowers the incidence of myocardial infarction, stroke, amputation of a lower extremity, a composite of death and the foregoing three events, the plasma homocysteine level, and, in ESRD patients undergoing hemodialysis, thrombosis of the vascular access. A unique feature of this trial is that after initial evaluation at enrollment and one return visit the follow up is exclusively by phone (or, if necessary, by mail). The subject is contacted every three months throughout the duration of the study from a central location. The study drug is shipped to the patient from a central location rather supplied locally. In a two year enrollment period, 2006 patients are to be enrolled. The duration of the observation period is four to six years. Data will be stored and analyzed at a coordinating center. The study design has the power to detect a reduction in all cause mortality rate of 17%. Issues related to the unique features of the design of this study are discussed.

The associations between smoking, physical activity, dietary habits and plasma homocysteine levels in cardiovascular disease-free people: the ‘ATTICA’ study

Homocysteine levels are considered, by some investigators, as an independent factor of cardiovascular disease; however, others suggest that there is not a causal relationship. The aim of this work was to investigate the associations between homocysteine levels and several lifestyle-related factors. The ATTICA study is a population-based cohort that has randomly enrolled 1128 adult men and 1154 women, stratified by age and gender, from the greater area of Athens, during 2001 2002. Among several demographic, lifestyle, clinical and biochemical characteristics, we measured total plasma homocysteine levels. For the present analysis, we excluded people who had a history of cardiovascular disease. The factors that showed the strongest relationship with homocysteine levels, in both genders, even after adjusting for several potential confounders were: cigarette smoking (p=0.03), endurance exercise (inverse, p<0.05), fruit (inverse, p=0.01) and vegetable intake (inverse, p=0.04), and alcohol (p=0.04) and coffee intake (p=0.04). In conclusion, several lifestyle-related factors seem to be associated with homocysteine levels. However, the vast majority of the associations were weak when we adjusted for other co-factors. The latter may indicate the mutual confounding effect of various socio-demographic, anthropometric and other clinical characteristics on the relationship between homocysteine and cardiovascular risk.

Lack of association between early atherosclerotic carotid artery wall lesions and serum level of homocysteine

The present study evaluated the possible association of high serum levels of homocysteine with ultrasonographic manifestations of carotid atherosclerosis in 65-year-old Finnish subjects drawn from a population-based cohort. Carotid ultrasonographic measurements were performed on 54 diabetic subjects, 97 subjects with impaired glucose tolerance and 57 normoglycaemic subjects. There were no statistically significant differences between the groups in the homocysteine levels. The median homocysteine level was higher in the subjects with a history of myocardial infarction (MI) (n=9) than in the subjects with no history of MI (14.8 [range 8.7—18.3] vs.12.3 [range 6.4—49.0] µmol/L, p=0.045). In the subjects without a history of MI or stroke, the maximal intima-media thickness (IMT) of the common carotid artery did not differ in the homocysteine quintiles. There was no association between the number of atheromatous plaques and the homocysteine level. In conclusion, although high levels of serum homocysteine were not associated with early atherosclerotic changes (i.e. increased carotid IMT or the number of plaques), high homocysteine concentrations were associated with advanced atherosclerosis (i.e. a history of MI).

Oxidative Stress in Renal Transplant Patients Who Develop Cardiovascular Disease

Cardiovascular disease limits life expectancy of successful renal transplant patients. Reactive oxygen species have been implicated in the development of atherosclerosis, and high levels could be due to increased production or a decrease in antioxidant reserve. Cardiovascular disease in renal transplant recipients could be due to elevated levels of malondialdehyde (an index of levels of reactive oxygen species) and homocysteine and reduced levels of glutathione. Renal transplant recipients with and without cardiovascular disease were studied along with healthy controls. Serum malondialdehyde, plasma homocysteine, and red blood cell glutathione were measured. The results suggest that levels of serum malondialdehyde and plasma homocysteine were higher in patients with or without cardiovascular disease compared with controls; however, the values were similar in both groups of transplant patients. Glutathione levels in red blood cells were similar in all 3 groups. Renal transplant recipients without cardiovascular disease have high levels of oxidative stress and may develop cardiovascular disease with time.

Long-term stability of cancer biomarkers in human serum: biomarkers of oxidative stress and redox status, homocysteine, CRP and the enzymes ALT and GGT

AIM

Five frequently used biomarkers in cancer research and epidemiological studies were tested for their assay stability upon storage of serum for 12 months at -20 and -70/-80°C.

MATERIALS & METHODS

The biomarker assays include reactive oxygen metabolites (ROM), the total thiol levels (TTL), homocysteine (HCy), C-reactive protein (HS-CRP) and two liver enzymes, alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT).

RESULTS

The assays for ROM, HCy, HS-CRP and GGT were stable in human serum samples at the two temperatures tested. The two other assays TTL and ALT, however, showed statistically significant differences in their stability between -20 and -80°C.

CONCLUSION

Therefore, storage at -80°C is advised to maintain a reliable assay outcome when serum samples have to be stored for longer periods.

Atherogenesis: hyperhomocysteinemia interactions with LDL, macrophage function, paraoxonase 1, and exercise

Despite great strides in understanding the atherogenesis process, the mechanisms are not entirely known. In addition to diet, cigarette smoking, genetic predisposition, and hypertension, hyperhomocysteinemia (HHcy), an accumulation of the noncoding sulfur-containing amino acid homocysteine (Hcy), is a significant contributor to atherogenesis. Although exercise decreases HHcy and increases longevity, the complete mechanism is unclear. In light of recent evidence, in this review, we focus on the effects of HHcy on macrophage function, differentiation, and polarization. Though there is need for further evidence, it is most likely that HHcy-mediated alterations in macrophage function are important contributors to atherogenesis, and HHcy-countering strategies, such as nutrition and exercise, should be included in the combinatorial regimens for effective prevention and regression of atherosclerotic plaques. Therefore, we also included a discussion on the effects of exercise on the HHcy-mediated atherogenic process.

Lipoprotein (a) as a risk factor for ischemic stroke: a meta-analysis

OBJECTIVE

Lipoprotein (a) [Lp(a)] harbors atherogenic potential but its role as a risk factor for ischemic stroke remains controversial. We conducted a meta-analysis to determine the relative strength of the association between Lp(a) and ischemic stroke and identify potential subgroup-specific risk differences.

METHODS

A systematic search using the MeSH terms "lipoproteins" OR "lipoprotein a" AND "stroke" was performed in PubMed and ScienceDirect for case-control studies from June 2006 and prospective cohort studies from April 2009 until December 20th 2014. Data from eligible papers published before these dates were reviewed and extracted from previous meta-analyses. Studies that assessed the relationship between Lp(a) levels and ischemic stroke and reported generic data-i.e. odds ratio [OR], hazard ratio, or risk ratio [RR]-were eligible for inclusion. Studies that not distinguish between ischemic and hemorrhagic stroke and transient ischemic attack were excluded. Random effects meta-analyses with mixed-effects meta-regression were performed by pooling adjusted OR or RR.

RESULTS

A total of 20 articles comprising 90,904 subjects and 5029 stroke events were eligible for the meta-analysis. Comparing high with low Lp(a) levels, the pooled estimated OR was 1.41 (95% CI, 1.26-1.57) for case-control studies (n = 11) and the pooled estimated RR was 1.29 (95% CI, 1.06-1.58) for prospective studies (n = 9). Sex-specific differences in RR were inconsistent between case-control and prospective studies. Study populations with a mean age of ≤55 years had an increased RR compared to older study populations. Reported Lp(a) contrast levels and ischemic stroke subtype significantly contributed to the heterogeneity observed in the analyses.

CONCLUSION

Elevated Lp(a) is an independent risk factor for ischemic stroke and may be especially relevant for young stroke patients. Sex-specific risk differences remain conflicting. Further studies in these subgroups may be warranted.

The Association Between Medical Treatment of Physical Diseases and Psychological Distress After the Great East Japan Earthquake: The Shichigahama Health Promotion Project

Objective

Physical disease patients are known to experience high levels of psychological distress. This study examined the association between the medical treatment of physical diseases and psychological distress in the coastal area affected by the Great East Japan Earthquake.

Methods

Using cross-sectional data, we studied 3032 individuals aged ≥40 years who lived in Shichigahama, Miyagi, Japan. We examined the associations between 8 medical treatments for physical diseases and psychological distress, defined as Kessler Psychological Distress scale score ≥13 of 24 points. To investigate the associations, we performed multiple logistic regression analyses.

Results

There were statistically significant associations between psychological distress and medical treatments for myocardial infarction/angina pectoris (odds ratio [OR]=1.8, 95% confidence interval [CI]=1.0-3.0) and liver disease (OR=3.1, 95% CI=1.0-7.7). The other 4 medical treatments for physical diseases had ORs of 1.3 or higher and were positively associated with psychological distress: cancer, hyperlipidemia, kidney disease, and diabetes mellitus. The degree of damage to homes did not affect the association between most of the medical treatments for physical diseases and psychological distress.

Conclusions

In the disaster area, most of the medical treatments for physical diseases had positive associations with psychological distress, irrespective of the degree of damage to homes. (Disaster Med Public Health Preparedness. 2015;9:374–381)

Plasma homocysteine, dietary B vitamins, betaine, and choline and risk of peripheral artery disease

OBJECTIVE

Few studies have examined the roles of homocysteine and related nutrients in the development of peripheral artery disease (PAD). We examined the associations between plasma homocysteine, dietary B vitamins, betaine, choline, and supplemental folic acid use and incidence of PAD.

METHODS

We used two cohort studies of 72,348 women in the Nurses' Health Study (NHS, 1990-2010) and 44,504 men in the Health Professionals Follow-up Study (HPFS, 1986-2010). We measured plasma homocysteine in nested matched case-control studies of clinically recognized PAD within both cohorts, including 143 PAD cases and 424 controls within the NHS (1990-2010) and 143 PAD cases and 428 controls within the HPFS (1994-2008). We examined the association between diet and risk of incident PAD in the cohorts using a food frequency questionnaire and 790 cases of PAD over 3.1 million person-years of follow-up.

RESULTS

Higher homocysteine levels were positively associated with risk of PAD in men (adjusted IRR 2.17; 95% CI, 1.08-4.38 for tertile 3 vs. 1). There was no evidence of an association in women (adjusted IRR 1.14; 95% CI, 0.61-2.12). Similarly, higher folate intake, including supplements, was inversely associated with risk of PAD in men (adjusted HR 0.90; 95% CI, 0.82-0.98 for each 250 μg increase) but not women (HR 1.01, 95% CI, 0.88-1.15). Intakes of the other B vitamins, betaine, and choline were not consistently associated with risk of PAD in men or women.

CONCLUSION

Homocysteine levels were positively associated and dietary folate intake was inversely associated with risk of PAD in men but not in women.

Relationship between Lipoprotein(a) and Thyroid Hormones in Hypothyroid Patients

BACKGROUND AND OBJECTIVE

Changes in plasma lipid concentrations are well known metabolic consequences of thyroid dysfunction. The alterations are most prominent in hypothyroidism which is typically associated with pronounced hypercholesterolaemia and frequently with moderate hypertriglyceridaemia. In cases of hypothyroidism, how the serum Lp(a) levels are influenced by thyroid hormone remains unknown and contradictory results on the effect of thyroid hormone on serum Lp(a) levels have been reported. There is substantial evidence to suggest that elevated serum Lp(a) levels contribute significantly to the development of CHD. The present study was designed to determine the lipoprotein(a) [Lp(a)], lipid profile and thyroid hormone levels in newly diagnosed hypothyroid patients and to find any correlation that existed between Lp(a) and other parameters.

MATERIALS AND METHODS

Untreated hypothyroid (n=50) patients were included in the study. We also included 40 normal healthy subjects as controls. Lipid profile, Lp(a) and thyroid profile were estimated by using autoanalyzers.

RESULTS

The results of this study showed that levels of HDL-cholesterol were significantly decreased (p<0.001), whereas those of other lipid parameters and Lp(a) levels were found to be significantly increased (p<0.001) in hypothyroid patients as compared to those in controls. Correlation study revealed a significant positive correlation between Lp(a) and TSH levels in hypothyroid patients.

CONCLUSION

Our present findings indicated that hypothyroidism could be strongly associated with lipid abnormalities that enhanced the development of cardiovascular diseases. Also, Lp(a) and non-HDL-C should be estimated with other lipid parameters as a useful index for measuring the cardiac risk in hypothyroid patients. A recommended screening should be advised for any patient with thyroid dysfunction, especially hypothyroidism, to assess lipid abnormalities by using Lp(a) and non- HDL-C and he/she should treated at the earliest.

Increased carotid intima-media thickness and plasma homocysteine levels predict cardiovascular and all-cause death: a population-based cohort study

BACKGROUND

There is still debate over the utility of carotid intima-media thickness (C-IMT) or carotid plaque in predicting future cardiovascular events and death. Additionally, the importance of plasma homocysteine levels was raised as a predictor of cardiovascular events and death.

METHODS

1,391 subjects were recruited from the Ansan Geriatric cohort. We used B-mode carotid ultrasonography to assess C-IMT and plaque, measuring average maximal IMT and average mean IMT through 6-8 measurements of far-wall IMT in both common carotid arteries. We evaluated the presence of plaque in carotid segments. Multivariable Cox regression analysis was used to predict both cardiovascular and all-cause mortality.

RESULTS

During a mean follow-up of 62.4 ± 12.4 months, 71 subjects (5.12%) died and 23 (1.66%) died of cardiovascular causes. Multivariable Cox regression analysis found the predictors of cardiovascular mortality to be average maximal IMT (HR = 3.709; 95% CI: 1.202-11.446) and plasma homocysteine (HR = 1.057; 95% CI: 1.012-1.103). All-cause mortality was independently associated with C-IMT (average maximal and average mean IMT) and plasma homocysteine.

CONCLUSIONS

C-IMT and plasma homocysteine levels were found to predict cardiovascular and all-cause mortality independently of the presence of carotid plaque and other cardiovascular risk factors.

Vitamin B12 deficiency and hyperhomocysteinemia as correlates of cardiovascular risk factors in Indian subjects with coronary artery disease

BACKGROUND AND PURPOSE

Folate and vitamin B12 are essential components in the metabolism of homocysteine (Hcy). Hyperhomocysteinemia has been implicated in endothelial dysfunction and cardiovascular disease. However, the association of Hcy, vitamin B12, and folic acid with cardiovascular risk factors in patients with coronary artery disease (CAD) has not been studied in Indian patients. This study was conducted with the aim to evaluate the relationship of vitamin B12, folic acid, and Hcy levels with cardiovascular risk factors in subjects with known CAD.

METHODS AND SUBJECTS

Three hundred patients (216 men; 84 women; aged 25-92 years) who had CAD on angiography were included in this study consecutively. All patients were evaluated for anthropometry and cardiovascular risk factors, and blood samples were collected for biochemical, nutritional, and inflammatory markers.

RESULTS

Percentage of vitamin B12 and folate deficiency was 86.7% and 2.7%, respectively. Hyperhomocysteinemia was present in 95.3% patients. Vitamin B12 levels were significantly lower and Hcy levels were significantly higher in subjects with dyslipidemia, DM, and/or hypertension. Serum vitamin B12 was inversely associated with triglyceride and very low-density lipoprotein (VLDL) and positively with high-density lipoprotein (HDL). Hcy was positively associated with triglyceride and VLDL and negatively with HDL. Vitamin B12 was inversely correlated with inflammatory markers (high-sensitivity C-reactive protein and interleukin-6) directly related to insulin resistance whereas Hcy showed the opposite pattern.

CONCLUSIONS

Serum vitamin B12 deficiency and hyperhomocysteinemia are related with cardiovascular risk factors in Indian patients with CAD.

Lipoprotein(a) in cardiovascular diseases

Lipoprotein(a) (Lp(a)) is an LDL-like molecule consisting of an apolipoprotein B-100 (apo(B-100)) particle attached by a disulphide bridge to apo(a). Many observations have pointed out that Lp(a) levels may be a risk factor for cardiovascular diseases. Lp(a) inhibits the activation of transforming growth factor (TGF) and contributes to the growth of arterial atherosclerotic lesions by promoting the proliferation of vascular smooth muscle cells and the migration of smooth muscle cells to endothelial cells. Moreover Lp(a) inhibits plasminogen binding to the surfaces of endothelial cells and decreases the activity of fibrin-dependent tissue-type plasminogen activator. Lp(a) may act as a proinflammatory mediator that augments the lesion formation in atherosclerotic plaques. Elevated serum Lp(a) is an independent predictor of coronary artery disease and myocardial infarction. Furthermore, Lp(a) levels should be a marker of restenosis after percutaneous transluminal coronary angioplasty, saphenous vein bypass graft atherosclerosis, and accelerated coronary atherosclerosis of cardiac transplantation. Finally, the possibility that Lp(a) may be a risk factor for ischemic stroke has been assessed in several studies. Recent findings suggest that Lp(a)-lowering therapy might be beneficial in patients with high Lp(a) levels. A future therapeutic approach could include apheresis in high-risk patients in order to reduce major coronary events.

Relationship between Occupational Stress and Gastric Disease in Male Workers

Background

Physical and mental health of workers is threatened due to various events and chronic occupational stress. This study was conducted to investigate the relationship between occupational stress and gastric disease in male workers of the shipbuilding industry.

Methods

Occupational stress measured among a total of 498 workers of a shipbuilding firm who visited the hospital for health examination using the Korean Occupational Stress Scale (KOSS)-short form, and the relationship between sociodemographic factors, health-related behaviors, occupational stress, and gastric disease, and the distribution of occupational stress by sociodemographic factors in the gastric disease group was examined.

Results

There was no significant association between gastric disease and total occupational stress score and its seven sub-factors. The analysis showed that risk of gastric disease was significantly higher in the Q1 group in which the stress caused by occupational discomfort among seven sub-factors was lowest than that in the Q4 group (odds ratio, 2.819; 95% confidence interval, 1.151 to 6.908). Analysis only on the gastric disease group showed that the stress score of laborers was higher in the four sub-factors than that of office workers (P < 0.05). Analysis on educational background showed that the scores of the three sub-factors were lower in subjects who's highest level of education was high school (P < 0.01).

Conclusion

This study suggests that it is necessary to improve the culture of Korean collectivism in the workplace and to manage the occupational stress in the low-educated and laborers. It is recommended for future studies to confirm the causal relationship between occupational stress and gastric disease by large scale studies using a KOSS which appropriately reflects workplace culture.

LDL-apheresis: technical and clinical aspects

The prognosis of patients suffering from severe hyperlipidemia, sometimes combined with elevated lipoprotein (a) levels, and coronary heart disease refractory to diet and lipid-lowering drugs is poor. For such patients, regular treatment with low-density lipoprotein (LDL) apheresis is the therapeutic option. Today, there are five different LDL-apheresis systems available: cascade filtration or lipid filtration, immunoadsorption, heparin-induced LDL precipitation, dextran sulfate LDL adsorption, and the LDL hemoperfusion. There is a strong correlation between hyperlipidemia and atherosclerosis. Besides the elimination of other risk factors, in severe hyperlipidemia therapeutic strategies should focus on a drastic reduction of serum lipoproteins. Despite maximum conventional therapy with a combination of different kinds of lipid-lowering drugs, sometimes the goal of therapy cannot be reached. Hence, in such patients, treatment with LDL-apheresis is indicated. Technical and clinical aspects of these five different LDL-apheresis methods are shown here. There were no significant differences with respect to or concerning all cholesterols, or triglycerides observed. With respect to elevated lipoprotein (a) levels, however, the immunoadsorption method seems to be most effective. The different published data clearly demonstrate that treatment with LDL-apheresis in patients suffering from severe hyperlipidemia refractory to maximum conservative therapy is effective and safe in long-term application.

Lipoprotein(a) and risk of myocardial infarction--genetic epidemiologic evidence of causality

Elevated levels of lipoprotein(a) are associated with an increased risk of myocardial infarction. Our study aimed to test whether genetic data are consistent with this association being causal. Accordingly, we developed a high-throughput realtime PCR assay to genotype for the lipoprotein(a) kringle IV type 2 (KIV-2) repeat polymorphism in the LPA gene in > 40,000 individuals. The LPA KIV-2 genotype associated with plasma levels of lipoprotein(a) (trend p < 0.001), and the LPA KIV-2 genotype associated with risk of myocardial infarction (trend p < 0.001 to 0.03) in a manner consistent with its effect on plasma levels of lipoprotein(a). The association of LPA KIV-2 genotypes raising plasma levels of lipoprotein(a) with increased risk of myocardial infarction strongly supports a causal association of lipoprotein(a) with risk of myocardial infarction.

Increased stroke risk and lipoprotein(a) in a multiethnic community: the Northern Manhattan Stroke Study

CONTEXT

Elevated lipoprotein(a) [Lp(a)] is associated with ischemic stroke (IS) among Whites, but data is sparse for non-White populations.

OBJECTIVE

Using a population-based case-control study design with subjects from the Northern Manhattan Stroke Study, we assessed whether Lp(a) levels were independently associated with IS risk among Whites, Blacks and Hispanics.

DESIGN AND SETTING

Lp(a) levels were measured in 317 IS cases (mean age 69 +/- 13 years; 56% women; 16% Whites, 31% Blacks and 52% Hispanics) and 413 community-based controls, matched by age, race/ethnicity and gender. In-person assessments included demographics, socioeconomic status, presence of vascular risk factors and fasting lipid levels. Logistic regression was used to determine the independent association of Lp(a) and IS. Stratified analyses investigated gender and race/ethnic differences.

RESULTS

Mean Lp(a) levels were greater among cases than controls (46.3 +/- 41.0 vs. 38.9 +/- 38.2 mg/dl; p < 0.01). After adjusting for stroke risk factors (hypertension, diabetes mellitus, coronary artery disease, cigarette smoking), lipid levels, and socioeconomic status, Lp(a) levels > or =30 mg/dl were independently associated with an increased stroke risk in the overall cohort (adjusted odds ratio, OR, 1.8, 95% confidence interval, CI, 1.20-2.6; p = 0.004). There was a significant linear dose-response relationship between Lp(a) levels and IS risk. The association between IS risk and Lp(a) > or =30 mg/dl was more pronounced among men (adjusted OR 2.0, 95% CI 1.1-3.5; p = 0.02) and among Blacks (adjusted OR 2.7, 95% CI 1.2-6.2; p = 0.02).

CONCLUSION

Elevated Lp(a) levels were significantly and independently associated with increased stroke risk, suggesting that Lp(a) is a risk factor for IS across White, Black and Hispanic race/ethnic groups.

Homocysteine is a risk factor in predialysis patients when associated with malnutrition and inflammation

The increased level of plasma total homocysteine (tHcy) in chronic kidney disease patients has been reported as a new and independent risk factor for cardiovascular disease. However, after the description of reverse epidemiology in the renal population, the association of tHcy and nutrition became less clear. We evaluated the association between homocysteine, nutritional status, and inflammation, and their impact on mortality in 95 predialysis patients. High sensitivity C-Reactive Protein (hs-CRP), interleukin 6 (IL-6), Tumor Necrosis Factor α (TNF-α)], and tHcy were evaluated, as was the nutritional status by the modified Subjective Global Nutritional Assessment (mSGA). We divided our population in four groups according to their tHcy and mSGA values being above or below the mean level and found the lowest survival in the group with tHcy and mSGA above the mean level, as well as higher levels of IL-6 (P = .03) and TNF-α (P = .045). Higher levels of homocysteine can be associated with higher mortality in predialysis patients, as long as they are associated with malnutrition and inflammation.

Lack of association between total serum homocysteine and extracranial cerebral flow

BACKGROUND/PURPOSE

High homocysteine (Hcy) concentration is associated with slow coronary flow. This study examined the association between Hcy and hemodynamic status in the extracranial cerebral arteries in healthy individuals.

METHODS

A total of 535 healthy adults underwent physical examination and duplex ultrasonography of the extracranial carotid and vertebral arteries, and blood laboratory tests, including biochemistry and serum total Hcy. Flow hemodynamic parameters including velocity, resistance, and volume of the carotid and vertebral arteries were measured. Multiple regression analysis was performed to examine the association between Hcy and the flow parameters.

RESULTS

Participants with higher Hcy were more likely to have a lower systolic velocity of the internal carotid artery (p = 0.01) and vertebral artery (p < 0.001), and lower resistance of the vertebral artery (p = 0.004). However, the multiple-adjusted means of the flow velocity, resistance, and flow volume of the carotid or vertebral artery were not significantly different across quartiles of Hcy. When Hcy was treated as a continuous variable, there was still no significant relationship between Hcy levels and the aforementioned hemodynamic status.

CONCLUSION

Our results did not support the hypothesis that the levels of Hcy are associated with the flow velocity, resistance, and volume of the extracranial cerebral artery in healthy individuals.

Lipoprotein(a) and ischemic heart disease--a causal association? A review

The aim of this review is to summarize present evidence of a causal association of lipoprotein(a) with risk of ischemic heart disease (IHD). Evidence for causality includes reproducible associations of a proposed risk factor with risk of disease in epidemiological studies, evidence from in vitro and animal studies in support of pathophysiological effects of the risk factor, and preferably evidence from randomized clinical trials documenting reduced morbidity in response to interventions targeting the risk factor. Elevated and in particular extreme lipoprotein(a) levels have in prospective studies repeatedly been associated with increased risk of IHD, although results from early studies are inconsistent. Data from in vitro and animal studies implicate lipoprotein(a), consisting of a low density lipoprotein particle covalently bound to the plasminogen-like glycoprotein apolipoprotein(a), in both atherosclerosis and thrombosis, including accumulation of lipoprotein(a) in atherosclerotic plaques and attenuation of t-PA mediated plasminogen activation. No randomized clinical trial of the effect of lowering lipoprotein(a) levels on IHD prevention has ever been conducted. Lacking evidence from randomized clinical trials, genetic studies, such as Mendelian randomization studies, can also support claims of causality. Levels of lipoprotein(a) are primarily determined by variation in the LPA gene coding for the apolipoprotein(a) moiety of lipoprotein(a), and genetic epidemiologic studies have documented association of LPA copy number variants, influencing levels of lipoprotein(a), with risk of IHD. In conclusion, results from epidemiologic, in vitro, animal, and genetic epidemiologic studies support a causal association of lipoprotein(a) with risk of IHD, while results from randomized clinical trials are presently lacking.

Impact of homocysteine-lowering vitamin therapy on long-term outcome of patients with coronary artery disease

Elevated homocysteine levels are associated with increased risk for mortality in patients with coronary artery disease (CAD). However, the benefit of homocysteine-lowering therapy remains controversial. The aim of this study was to examine the impact of homocysteine-lowering therapy on the long-term outcomes of patients with CAD and its interaction with the methylenetetrahydrofolate reductase genotype. The study sample included 492 patients with early-onset CAD who were genotyped for the C677T mutation in the methylenetetrahydrofolate reductase gene or screened for elevated homocysteine from January 1997 to December 2002. Folic acid > or =400 microg/day with or without additional B vitamins was administered at the attending physicians' discretion. There was no difference between treated (n = 140) and untreated patients in age, gender, or prevalence of coronary risk factors. Forty-six patients (9%) died during a median follow-up period of 115 months. Treatment was associated with significantly lower all-cause mortality in patients with homocysteine levels >15 micromol/L (4% vs 32%, p <0.001) but not in patients with lower levels (5% vs 7%, p >0.05). On Cox regression analysis, the following factors were independently associated with all-cause mortality: vitamin therapy (hazard ratio 0.33, 95% confidence interval 0.11 to 0.98, p = 0.046), elevated homocysteine level (hazard ratio 3.5, 95% confidence interval 1.31 to 9.43, p = 0.013), and older age (hazard ratio 1.1, 95% confidence interval 1.04 to 1.14, p <0.0001 for an increment of 5 years). The methylenetetrahydrofolate reductase genotype was not associated with outcomes. In conclusion, long-term folate-based vitamin therapy was independently associated with lower all-cause mortality in patients with CAD and elevated homocysteine levels. This association was not observed in patients with lower homocysteine levels.

Lipoprotein(a) concentration and the risk of coronary heart disease, stroke, and nonvascular mortality

CONTEXT

Circulating concentration of lipoprotein(a) (Lp[a]), a large glycoprotein attached to a low-density lipoprotein-like particle, may be associated with risk of coronary heart disease (CHD) and stroke.

OBJECTIVE

To assess the relationship of Lp(a) concentration with risk of major vascular and nonvascular outcomes.

STUDY SELECTION

Long-term prospective studies that recorded Lp(a) concentration and subsequent major vascular morbidity and/or cause-specific mortality published between January 1970 and March 2009 were identified through electronic searches of MEDLINE and other databases, manual searches of reference lists, and discussion with collaborators.

DATA EXTRACTION

Individual records were provided for each of 126,634 participants in 36 prospective studies. During 1.3 million person-years of follow-up, 22,076 first-ever fatal or nonfatal vascular disease outcomes or nonvascular deaths were recorded, including 9336 CHD outcomes, 1903 ischemic strokes, 338 hemorrhagic strokes, 751 unclassified strokes, 1091 other vascular deaths, 8114 nonvascular deaths, and 242 deaths of unknown cause. Within-study regression analyses were adjusted for within-person variation and combined using meta-analysis. Analyses excluded participants with known preexisting CHD or stroke at baseline.

DATA SYNTHESIS

Lipoprotein(a) concentration was weakly correlated with several conventional vascular risk factors and it was highly consistent within individuals over several years. Associations of Lp(a) with CHD risk were broadly continuous in shape. In the 24 cohort studies, the rates of CHD in the top and bottom thirds of baseline Lp(a) distributions, respectively, were 5.6 (95% confidence interval [CI], 5.4-5.9) per 1000 person-years and 4.4 (95% CI, 4.2-4.6) per 1000 person-years. The risk ratio for CHD, adjusted for age and sex only, was 1.16 (95% CI, 1.11-1.22) per 3.5-fold higher usual Lp(a) concentration (ie, per 1 SD), and it was 1.13 (95% CI, 1.09-1.18) following further adjustment for lipids and other conventional risk factors. The corresponding adjusted risk ratios were 1.10 (95% CI, 1.02-1.18) for ischemic stroke, 1.01 (95% CI, 0.98-1.05) for the aggregate of nonvascular mortality, 1.00 (95% CI, 0.97-1.04) for cancer deaths, and 1.00 (95% CI, 0.95-1.06) for nonvascular deaths other than cancer.

CONCLUSION

Under a wide range of circumstances, there are continuous, independent, and modest associations of Lp(a) concentration with risk of CHD and stroke that appear exclusive to vascular outcomes.

Use of serum homocysteine to predict stroke, coronary heart disease and death in ethnic Chinese. 12-year prospective cohort study

BACKGROUND

Prospective data about the association between serum total homocysteine (Hcy) and vascular disease in Asia is limited because few investigations have evaluated the cutpoint of Hcy for predicting the risk of vascular disease and death.

METHODS AND RESULTS

A community-based prospective cohort study of 2,009 participants, who were free from stroke, coronary heart disease (CHD) and cancer at baseline in 1994 were followed up to 2007 (median 11.95 years); there were 114 documented cases of stroke, 95 of CHD and 380 deaths. Cox proportional hazard model was used to examine the association between Hcy and the incidence of stroke, CHD, and all-cause death. The receiver-operating characteristic curve was performed for determining the cutpoint of Hcy in risk prediction. Hcy levels remained significantly associated with cardiovascular events and death in fully adjusted models. Participants with Hcy >9.47 micromol/L (sensitivity 81.1%, specificity 54.3%) had a 2.3-fold risk for cardiovascular events (95% confidence interval (CI), 1.24-4.18, P=0.008), and participants with Hcy >11.84 micromol/L (sensitivity 49.7%, specificity 84.0%) had a 2.4-fold risk for death (95%CI, 1.76-3.32, P<0.0001).

CONCLUSIONS

Hcy was significantly related to cardiovascular events and all-cause death, with the best cutpoint values as 9.47 and 11.84, respectively.