Lipoprotein(a) associated with coronary artery disease in older women: age and gender analysis

Lipoprotein(a): Knowns, unknowns and uncertainties

Over the last 10 years, there have been advances on several aspects of lipoprotein(a) which are reviewed in the present article. Since the standard immunoassays for measuring lipoprotein(a) are not fully apo(a) isoform-insensitive, the application of an LC-MS/MS method for assaying molar concentrations of lipoprotein(a) has been advocated. Genome wide association, epidemiological, and clinical studies have established high lipoprotein(a) as a causal risk factor for atherosclerotic cardiovascular diseases (ASCVD). However, the relative importance of molar concentration, apo(a) isoform size or variants within the LPA gene is still controversial. Lipoprotein(a)-raising single nucleotide polymorphisms has not been shown to add on value in predicting ASCVD beyond lipoprotein(a) concentrations. Although hyperlipoproteinemia(a) represents an important confounder in the diagnosis of familial hypercholesterolemia (FH), it enhances the risk of ASCVD in these patients. Thus, identification of new cases of hyperlipoproteinemia(a) during cascade testing can increase the identification of high-risk individuals. However, it remains unclear whether FH itself increases lipoprotein(a). The ASCVD risk associated with lipoprotein(a) seems to follow a linear gradient across the distribution, regardless of racial subgroups and other risk factors. The inverse association with the risk of developing type 2 diabetes needs consideration as effective lipoprotein(a) lowering therapies are progressing towards the market. Considering that Mendelian randomization analyses have identified the degree of lipoprotein(a)-lowering that is required to achieve ASCVD benefit, the findings of the ongoing outcome trial with pelacarsen will clarify whether dramatically lowering lipoprotein(a) levels can reduce the risk of ASCVD.

Elevated Lipoprotein A in South Asians and the Associated Risk of Cardiovascular Disease: A Systematic Review

BACKGROUND

South Asians have a premature risk of cardiovascular disease and increased lipoprotein A which enhances their risk.

METHODS

This systematic review evaluates the role of elevated lipoprotein A in cardiovascular disease risk for South Asians. It discusses the pathophysiology, clinical studies, and treatment of elevated lipoprotein A using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses method.

RESULTS

A total of 72 articles was incorporated which consisted of clinical studies, case-control and cohort studies, meta-analysis, reviews, and editorials. Cardiovascular disease and myocardial infarction occurs prematurely in South Asians, which is further enhanced with an elevated lipoprotein A.

CONCLUSIONS

South Asians with an elevated lipoprotein A have an increased risk of coronary artery disease so they should have early enactment of lifestyle modification and aggressive medical management.

Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of stroke among individuals who have not previously experienced a stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches to atherosclerotic disease of the cervicocephalic circulation, and antithrombotic treatments for preventing thrombotic and thromboembolic stroke. Further recommendations are provided for genetic and pharmacogenetic testing and for the prevention of stroke in a variety of other specific circumstances, including sickle cell disease and patent foramen ovale.

Guidelines for the primary prevention of stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

This guideline provides an overview of the evidence on established and emerging risk factors for stroke to provide evidence-based recommendations for the reduction of risk of a first stroke.

METHODS

Writing group members were nominated by the committee chair on the basis of their previous work in relevant topic areas and were approved by the American Heart Association (AHA) Stroke Council Scientific Statement Oversight Committee and the AHA Manuscript Oversight Committee. The writing group used systematic literature reviews (covering the time since the last review was published in 2006 up to April 2009), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations using standard AHA criteria (Tables 1 and 2). All members of the writing group had the opportunity to comment on the recommendations and approved the final version of this document. The guideline underwent extensive peer review by the Stroke Council leadership and the AHA scientific statements oversight committees before consideration and approval by the AHA Science Advisory and Coordinating Committee.

RESULTS

Schemes for assessing a person's risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic predisposition. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, excessive alcohol consumption, drug abuse, use of oral contraceptives, sleep-disordered breathing, migraine, hyperhomocysteinemia, elevated lipoprotein(a), hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

CONCLUSIONS

Extensive evidence identifies a variety of specific factors that increase the risk of a first stroke and that provide strategies for reducing that risk.

High Lipoprotein(a) Levels are Associated With Long-Term Adverse Outcomes in Acute Myocardial Infarction Patients in High Killip Classes

Background and Objectives

An elevated concentration of lipoprotein(a) {Lp(a)} is associated with an increased prevalence and increased severity of coronary artery disease. However, the relationship between Lp(a) levels and outcomes after acute myocardial infarction (AMI) is unclear.

Subjects and Methods

Between October 2005 and June 2007, we measured serum Lp(a) levels in 832 consecutive AMI patients (age, 62.8±12.4 years, 600 men) on admission. They were divided into tertiles according to their serum Lp(a) levels {Tertile 1 (n=276), Lp(a)<13.8 mg/dL; Tertile 2 (n=279), Lp(a)=13.8-30.6 mg/dL; Tertile 3 (n=277), Lp(a)>30.6 mg/dL}.

Results

There were no differences in baseline clinical characteristics among Tertiles 1, 2, and 3, except for proportions of Killip class III-IV patients (5.8% vs. 10.0% vs. 18.8%, respectively, p<0.001). There were significant differences in left ventricular ejection fractions (57.3±11.4% vs. 55.9±12.3% vs. 53.1±13.1%, p<0.001). Among the laboratory findings, there were significant differences in total cholesterol (173.3±37.2 vs. 183.5±38.9 vs. 185.3±43.8 mg/dL, p=0.001), low density lipoprotein-cholesterol (111.3±34.3 vs. 122.9±34.7 vs. 123.3±39.4 mg/dL, p<0.001), apolipoprotein B (92.8±25.4 vs. 100.8±26.0 vs. 101.9±28.8 mg/dL, p<0.001), and amino-terminal pro-brain natriuretic peptide levels (1805.2±4343.3 vs. 2607.9±5216.3 vs. 3981.5±7689.7 pg/mL, p<0.001). After adjusting for multiple variables in the high Killip class (III-IV) subgroup, the risk estimate for major adverse cardiovascular events (MACE) at 1-year follow-up was significantly higher in Tertile 3 than in Tertiles 1 or 2 (hazard ratio 6.723, 95% confidence interval 1.037-43.593, p=0.046).

Conclusion

In patients in high Killip classes, high serum levels of Lp(a) were significantly associated with long-term adverse outcomes after AMI.

Determinants of risk factors of atherosclerosis in the postinfarction period: The Tallinn MI Study

Environmental as well as genetic factors are involved in the pathogenesis of myocardial infarction. The disease is a frequent cause of mortality in the middle-aged male population of Estonia. The high prevalence of premature myocardial infarction (PMI) in this country is not fully understood. The association of atherogenic and thrombogenetic risk factors with lifestyle was evaluated in men who had suffered myocardial infarction at 55 years of age (n = 71) and in randomly selected corresponding controls (n = 85). Serum routine lipids, apolipoprotein (apo)A-I, apoB, apoE polymorphism, lipoprotein(a) and fibrinogen levels were determined. Behavioural risk factors, indices of obesity, blood pressure and pedigree data were registered. In 80.6 % of PMI subjects some type of hyperlipidaemia was observed (European Atherosclerosis Society Classification) and lipid-lowering drugs were taken by 13.9 % of patients. In PMI patients the most common positive determinants of atherogenic lipoprotein indices were waist-to-hip ratio and physical inactivity, and in controls, waist-to-hip ratio and apoE phenotype. The odds ratio (OR) of PMI was 8.9-fold greater in the highest tertile of apoB/apoA-I distribution compared with the lowest tertile. The OR of PMI in the highest tertile of fibrinogen distribution versus the lowest tertile was 6.2 (95 % CI 2.46-15.44), and OR of PMI in the highest Lp(a) tertile versus the lowest was 3.1 (95 % CI 1.31-7.40). Thus, atherogenic dyslipidaemia was the most serious cardiovascular risk factor among PMI patients. From two thrombogenesis-related markers, the levels of fibrinogen and Lp(a), the first one was more strongly associated with PMI status.

Interactions of lipoprotein(a) with diabetes mellitus, apolipoprotein B and cholesterol enhance the prognostic values for coronary artery disease

BACKGROUND

Synergistic interactions between elevated serum lipoprotein(a) [Lp(a)] and other unfavorable risk factors have been proposed to cause very high risk for coronary artery disease (CAD). The aim of this study was to examine the potential interactions between Lp(a) and other risk factors.

METHODS

The profiles of serum (apo)(lipo)proteins, markers of inflammation, indicators of hemoconcentration as well as classical risk factors were determined in 264 clinically stable angiographically documented subjects. Correlation, linear and logistic regression and stratification analyses were performed.

RESULTS

The frequency and severity of CAD and the prevalence of diabetes mellitus were significantly higher in the 3rd relative to 1st tertile of Lp(a). Subjects with Lp(a) levels in the upper tertile had significantly higher levels of serum glucose, total cholesterol and low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (apoB), calcium, phosphate and their ion product. Bivariate correlation analysis indicated that serum Lp(a) was associated positively with the occurrence and severity of CAD, diabetes mellitus and the levels of serum glucose, cholesterol, LDL-C, apoB, calcium, phosphate and inversely to physical inactivity. In linear regression analysis, LDL-C (or apoB), diabetes, physical inactivity and phosphate were the major independent determinants of Lp(a) values. In multiple logistic regression analysis, after adjusting for major risk factors, Lp(a) showed a significant and independent association with the prevalence of CAD. By constructing dummy combined variables, elevated Lp(a) accompanied with diabetes or high levels of serum glucose, apoB and cholesterol exhibited an amplified high risk for CAD.

CONCLUSIONS

The results indicate that serum Lp(a) does interact multiplicatively with diabetes, apoB and cholesterol. The simultaneous assessment of Lp(a) and interactive risk factors enhances the discriminating value for CAD.

Gender Differences in Adhering to National Guidelines in a Community Lipid Clinic

The aggressive treatment of hypercholesterolemia improves morbidity and mortality in patients with a history of cardiovascular disease irrespective of gender. Electronically tracked data on 4324 patients enrolled in a community lipid clinic were analyzed for gender differences in lipid values and adherence to national guidelines in lipid management. Women were older, more likely to be diabetic and/or hypertensive, and have a family history of coronary heart disease. Women also had higher initial total cholesterol, low-density lipoprotein, and triglyceride levels and were more likely to be at goal at entry for high-density lipoprotein. Men were more likely to have coronary heart disease and lower high-density lipoprotein and were more likely to be at goal at entry for triglyceride level. There were no gender differences in low-density lipoprotein at goal at entry or rate of current smoking. All lipid parameters appeared better with age, irrespective of gender. More men than women reached goal for their low-density lipoprotein (61.5% vs 51.7%) and triglyceride (36.9% vs 25.1%) levels, whereas more women than men reached goal for their high-density lipoprotein (33.1% vs 22.2%). The authors conclude that there are significant gender differences in lipid values at entry to a community lipid clinic and in achieving National Cholesterol Education Program targets following the initiation of therapy. A possible gender-independent survivorship effect exists for low-density lipoprotein and high-density lipoprotein.

Evidence-based treatment of lipids in the elderly

The elderly (men aged 65 years and older and women aged 75 years and older) constitute a population at high absolute risk for the morbidity and mortality of atherosclerotic cardiovascular disease. Statins have been shown in multiple large trials to reduce the burden of atherosclerotic disease in both middle-aged and elderly patients at elevated risk for coronary events, stroke, and death. We reviewed the major statin trials with particular emphasis on the significant number of elderly subjects. The impact of statins on the elderly, both positive and negative, is tabulated. In addition, we briefly discuss risk assessment in the elderly because selection of elderly patients for intensive low-density lipoprotein cholesterol reduction with statins requires clinical judgment that must weigh the need for subclinical measures of atherosclerosis. We also consider negative aspects, risks, and costs of such therapy.

Gender, hyperlipidemia, and coronary artery disease

The importance of statins for the prevention and treatment of coronary artery disease (CAD), the recent paradoxical effects of hormone replacement therapy on prevention of CAD, and the role of nontraditional risk factors in CAD in women are examined.

The role of non-LDL:non-HDL particles in atherosclerosis

Elevated concentrations of circulating apolipoprotein B (apoB)-containing lipoproteins, other than low-density lipoprotein (LDL), have been implicated as causative agents for the development of atherosclerosis. A form of dyslipidemia, the atherogenic lipoprotein profile, that consists of elevated intermediate-density lipoprotein (IDL), triglycerides (TGs), dense LDL and dense very low density lipoprotein (VLDL), and low high density lipoprotein-2, occurs in 40% to 50% of patients with coronary artery disease (CAD). The recently released Adult Treatment Panel III guidelines suggest that because elevated TGs are an independent CAD risk factor, some TG-rich lipoproteins, commonly called remnant lipoproteins, must be atherogenic. Relevant to this series on diabetes, a number of studies have shown that in type 2 diabetes, the severity of CAD is positively related to the numbers of TG-rich particles in the plasma. Although less clear, other studies in type 2 diabetes suggest that elevated levels of lipoprotein (a) [Lp(a)] may also be independently associated with CAD. In this article, we summarize evidence for the role of apoB-containing lipoprotein particles other than LDL in the development of atherosclerosis and discuss methods of quantification and possible pharmacologic interventions for lowering their plasma concentrations. The particles reviewed include the TG-rich lipoproteins: VLDL and its remnants, chylomicron remnants and IDL, and the C-rich lipoprotein: Lp(a).