Use of lipoprotein particle measures for assessing coronary heart disease risk post-American Heart Association/American College of Cardiology guidelines: the Multi-Ethnic Study of Atherosclerosis

Association of LDL-cholesterol subfractions with cardiovascular disorders: a systematic review

BACKGROUND

Cardiovascular disorders (CVDs) are the leading cause of death worldwide. This study aimed to evaluate the association between low-density lipoprotein (LDL) subfractions and cardiovascular disorders.

METHODS

To ensure the rigor of the systematic review, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. For this systematic review, a comprehensive search strategy was performed in important databases including PubMed, Scopus, Embase, International Statistical Institute (ISI) Web of Science, and google scholar from 2009 to February 2021. The following terms were used for systematic search: low-density lipoprotein, LDL, subfractions, subclasses, nuclear magnetic resonance, NMR, chromatography, high-pressure liquid, HPLC, cardiovascular disease, cerebrovascular, and peripheral vascular disease. Also, for evaluating the risk of bias, the Newcastle-Ottawa scale was employed.

RESULTS

At the end of the search process, 33 articles were included in this study. The results of most of the evaluated studies revealed that a higher LDL particle number was consistently associated with increased risk for cardiovascular disease, independent of other lipid measurements. Also, small dense LDL was associated with an increased risk of CVDs. There was no association between LDL subfraction and CVDs in a small number of studies.

CONCLUSIONS

Overall, it seems that the evaluation of LDL subclasses can be used as a very suitable biomarker for the assessment and diagnosis of cardiovascular diseases. However, further studies are required to identify the mechanisms involved.

Apolipoprotein Particle and Cardiovascular Risk Prediction (from a Prospective Cohort Study)

The present study aimed to examine the association between discordant apolipoprotein B (Apo B) with low-density lipoprotein cholesterol (LDL-C) or non-high-density lipoprotein cholesterol (non-HDL-C) and cardiovascular disease (CVD) risk in the Chinese population and to determine whether adding information on Apo B to LDL-C and HDL-C improves CVD risk prediction. This study collected data from the China Health and Nutrition Survey from 2009 to 2015. Discordant Apo B with LDL-C and non-HDL-C were defined based on residual differences and medians. Logistic regression was used to examine the association between discordant Apo B with LDL-C or non-HDL-C and CVD risk. Areas under the receiver operating characteristic curve and categorical net reclassification improvement were utilized to assess the incremental predictive value of Apo B levels for CVD risk. A total of 7,117 participants were included, the mean age was 50.8 ± 14.3 years, 53.6% were female. During the 6-year follow-up, 207 CVD cases were identified. Participants with discordant high Apo B relative to LDL-C or non-HDL-C were at higher risk of CVD than those with the concordant group (odds ratio 1.38, 95% confidence interval 1.01 to 1.87; odds ratio 1.40, 95% confidence interval 1.01 to 1.94, respectively). However, Apo B had no significant contribution to the predictive value of the China atherosclerotic CVD (ASCVD) risk score (areas under the receiver operating characteristic curve 0.788 for China ASCVD score alone vs 0.790 for China ASCVD score plus Apo B). In conclusion, Apo B has the strongest association with CVD risk in healthy Chinese participants than LDL-C and non-HDL-C. However, it has minimal value in CVD risk assessment and discrimination.

The benefits of measuring the size and number of lipoprotein particles for cardiovascular risk prediction: A systematic review and meta-analysis

OBJECTIVE

Cardiovascular risk (CVR) is conventionally calculated by measuring the total cholesterol content of high-density lipoproteins (HDL) and low-density lipoproteins (LDL). The purpose of this systematic review was to assess the CVR associated with LDL and HDL particle size and number as determined by nuclear magnetic resonance (NMR) spectroscopy.

MATERIAL AND METHODS

A literature search was performed using the electronic databases MEDLINE and Scopus. All cohort and case-control studies published before January 1, 2019 that met the following inclusion criteria were included: HDL-P, LDL-P, HDL-Z and/or LDL-Z measured by NMR spectroscopy; cardiovascular event as an outcome variable; risk of cardiovascular events expressed as odds ratios or hazard ratios; only adult patients. A meta-analysis was performed for each exposure variable (4 for LDL and 5 for HDL) and for each exposure measure (highest versus lowest quartile and 1-standard deviation increment).

RESULTS

This review included 24 studies. Number of LDL particles was directly associated with CVR: risk increased by 28% with each standard deviation increment. LDL particle size was inversely and significantly associated with CVR: each standard deviation increment corresponded to an 8% risk reduction. CVR increased by 12% with each standard deviation increase in number of small LDL particles. HD, particle number and size were inversely associated with CVR.

CONCLUSION

Larger particle size provided greater protection, although this relationship was inconsistent between studies. Larger number of LDL particles and smaller LDL particle size are associated with increased CVR. Risk decreases with increasing number and size of HDL particles.

Risk Markers for Limited Coronary Artery Calcium in Persons With Significant Aortic Valve Calcium (From the Multi-ethnic Study of Atherosclerosis)

The early stages of aortic valve calcification (AVC) and coronary artery calcification (CAC) include shared ASCVD risk factors, yet there is considerable heterogeneity between the burden of AVC, and CAC. We sought to identify the markers associated with limited CAC among persons with significant AVC. There were 325 participants from the Multi-Ethnic Study of Atherosclerosis without clinical ASCVD and with AVC ≥100 Agatston units (AU) at Visit 1. Multivariable-adjusted prevalence ratios for limited CAC (0 to 99 AU) were calculated using modified Poisson regression. Participants had a mean age of 72.1 years, median AVC score of 209, and 34% were women. A total of 133 (41%) participants had CAC <100, of whom 46/133 had CAC = 0. Younger age (PR = 1.40, 95% CI: 1.22 to 1.62, per 10-years), female gender (PR = 1.68, 95% CI: 1.28 to 2.20), and low 10-year ASCVD risk (PR = 2.30, 95% CI: 1.85 to 2.85) were most strongly associated with limited CAC. Neither a normal lipoprotein(a) nor normal measures of inflammation were significantly associated with limited CAC. Lower serum phosphate (PR = 1.15, 95% CI: 1.01 to 1.31; per 0.5 mg/dl lower) and calcium-phosphate product (PR = 1.16, 95% CI: 1.02 to 1.34; per SD lower) were associated with an approximately 15% higher prevalence of limited CAC. In conclusion, more than 40% of persons with significant AVC had CAC. Beyond traditional risk factors, lower serum phosphate, and lower calcium-phosphate product were associated with a higher prevalence of limited CAC.

Predictive value of carotid artery ultrasonography for the risk of coronary artery disease

PURPOSE

To assess carotid intima-media thickness (IMT), carotid plaques, and cardiovascular risk factors in patients with suspected coronary artery disease (CHD) to determine their association and predictive value for CHD.

METHODS

We performed duplex Doppler ultrasonography of the carotid arteries and coronary angiography or CT in 480 patients with suspected CHD, and investigated their personal and medical histories. Patients were then assigned to the CHD or the control group depending on the presence of coronary lesions. Ultrasonography was performed the morning after admission prior to any treatment, coronary angiography, or CT.

RESULTS

Carotid plaques were mainly distributed in the common carotid artery bifurcation, with a significant difference between the CHD and control groups. Plaque incidence (80%) and IMT were significantly higher (P < .001 and P = .012, respectively) in the CHD (80% and 0.84 ± 0.21 mm) than in the control group (49% and 0.76 ± 0.18 mm). The factors significantly associated with CHD were introduced into a multivariate regression model. Male subject (OR = 1.569, 95%CI 1.004-2.453; P = .048) and plaque burden (OR = 0.457, 95%CI 0.210-0.993; P = .048) were significant predictors for CHD occurrence. The presence of carotid plaques performed significantly better than IMT and the Framingham risk score for predicting CHD lesions (P < .001 for both).

CONCLUSIONS

CHD patients showed higher percentage of clinical (plaques) or subclinical (IMT) carotid artery wall change, and the presence of carotid plaques showed better predictive value than IMT and Framingham risk score for the presence of coronary artery lesions.

Effects of Virgin Olive Oil and Phenol-Enriched Virgin Olive Oils on Lipoprotein Atherogenicity

The atherogenicity of low-density lipoprotein (LDL) and triglyceride-rich lipoproteins (TRLs) may be more significant than LDL cholesterol levels. Clinical trials which have led to increased high-density lipoprotein (HDL) cholesterol have not always seen reductions in cardiovascular disease (CVD). Furthermore, genetic variants predisposing individuals to high HDL cholesterol are not associated with a lower risk of suffering a coronary event, and therefore HDL functionality is considered to be the most relevant aspect. Virgin olive oil (VOO) is thought to play a protective role against CVD. This review describes the effects of VOO and phenol-enriched VOOs on lipoprotein atherogenicity and HDL atheroprotective properties. The studies have demonstrated a decrease in LDL atherogenicity and an increase in the HDL-mediated macrophage cholesterol efflux capacity, HDL antioxidant activity, and HDL anti-inflammatory characteristics after various VOO interventions. Moreover, the expression of cholesterol efflux-related genes was enhanced after exposure to phenol-enriched VOOs in both post-prandial and sustained trials. Improvements in HDL antioxidant properties were also observed after VOO and phenol-enriched VOO interventions. Furthermore, some studies have demonstrated improved characteristics of TRL atherogenicity under postprandial conditions after VOO intake. Large-scale, long-term randomized clinical trials, and Mendelian analyses which assess the lipoprotein state and properties, are required to confirm these results.

Apolipoprotein B discordance with low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol in relation to coronary artery calcification in the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Discordant levels of apolipoprotein B (apo B) relative to low-density lipoprotein cholesterol (LDL-C) or non-high-density lipoprotein cholesterol (non-HDL-C) may be associated with subclinical atherosclerotic cardiovascular disease (ASCVD).

OBJECTIVE

The present study investigated whether discordance between apo B and LDL-C or non-HDL-C levels was associated with subclinical ASCVD measured by coronary artery calcium (CAC).

METHODS

This study was conducted in a subpopulation of the Multi-Ethnic Study of Atherosclerosis (MESA) cohort, aged 45 to 84 years, free of ASCVD, and not taking lipid-lowering medications at the baseline (2000-2002) (prevalence analytic N = 4623; incidence analytic N = 2216; progression analytic N = 3947). Apo B discordance relative to LDL-C and non-HDL-C was defined using residuals and percentile rankings (>5/10/15 percentile). Associations with prevalent and incident CAC (CAC > 0 vs CAC = 0) were assessed using prevalence ratio/relative risk regression and CAC progression (absolute increase/year) using multinomial logistic regression.

RESULTS

Higher apo B levels were associated with CAC prevalence, incidence, and progression. Apo B discordance relative to LDL-C or non-HDL-C was inconsistently associated with CAC prevalence and progression. Discordantly high apo B relative to LDL-C and non-HDL-C was associated with CAC progression. Associations for apo B discordance with non-HDL-C remained after further adjustment for metabolic syndrome components.

CONCLUSION

Apo B was associated with CAC among adults aged ≥45 years not taking statins, but provided only modest additional predictive value of apo B for CAC prevalence, incidence, or progression beyond LDL-C or non-HDL-C. Apo B discordance may still be important for ASCVD risk assessment and further research is needed to confirm findings.

Association of long-term PM2.5 exposure with traditional and novel lipid measures related to cardiovascular disease risk

BACKGROUND

Fine particulate matter (PM_2.5) exposure is associated with increased morbidity and mortality, particularly for cardiovascular disease. The association between long-term exposure to PM_2.5 and measures of lipoprotein subfractions remains unclear. Therefore, we examined associations between long-term PM_2.5 exposure and traditional and novel lipoprotein measures in a cardiac catheterization cohort in North Carolina.

METHODS

This cross-sectional study included 6587 patients who had visited Duke University for a cardiac catheterization between 2001 and 2010 and resided in North Carolina. We used estimates of daily PM_2.5 concentrations on a 1 km-grid based on satellite measurements. PM_2.5 predictions were matched to the address of each patient and averaged for the year prior to catheterization date. Serum lipids included HDL, LDL, and triglyceride-rich particle, and apolipoprotein B concentrations (HDL-P, LDL-P, TRL-P, and apoB, respectively). Linear and quantile regression models were used to estimate change in lipoprotein levels with each μg/m³ increase in annual average PM_2.5. Models were adjusted for age, sex, race/ethnicity, history of smoking, area-level education, urban/rural status, body mass index, and diabetes.

RESULTS

For a 1-μg/m³ increment in PM_2.5 exposure, we observed increases in total and small LDL-P, LDL-C, TRL-P, apoB, total cholesterol, and triglycerides. The percent change from the mean outcome level was 2.00% (95% CI: 1.38%, 2.64%) for total LDL-P and 2.25% (95% CI: 1.43%, 3.06%) for small LDL-P.

CONCLUSION

Among this sample of cardiac catheterization patients residing in North Carolina, long-term PM_2.5 exposure was associated with increases in several lipoprotein concentrations. This abstract does not necessarily reflect U.S. EPA policy.

Nonfasting versus fasting lipid profile for cardiovascular risk prediction

Before 2009 essentially all societies, guidelines, and statements required fasting before measuring a lipid profile for cardiovascular risk prediction. This was mainly due to the increase seen in triglycerides during a fat tolerance test. However, individuals eat much less fat during a normal day and nonfasting triglycerides have been shown to be superior to fasting in predicting cardiovascular risk. Lipids and lipoproteins only change minimally in response to normal food intake: in four large prospective studies, maximal mean changes were +0.3 mmol/L (26 mg/dL) for triglycerides, -0.2 mmol/L (8 mg/dL) for total cholesterol, -0.2 mmol/L (8 mg/dL) for LDL cholesterol, and -0.1 mmol/L (4 mg/dL) for HDL cholesterol. Further, in 108,602 individuals from the Copenhagen General Population Study in random nonfasting samples, the highest versus the lowest quartile of triglycerides, total cholesterol, LDL cholesterol, remnant cholesterol, non-HDL cholesterol, lipoprotein(a), and apolipoprotein B were all associated with higher risk of both ischaemic heart disease and myocardial infarction. Finally, lipid-lowering trials using nonfasting blood samples for assessment of lipid levels found that reducing levels of nonfasting lipids reduced the risk of cardiovascular disease. To date there is no sound scientific evidence as to why fasting should be superior to nonfasting when evaluating a lipid profile for cardiovascular risk prediction. Indeed, nonfasting samples rather than fasting samples have many obvious advantages. First, it would simplify blood sampling in the laboratory. Second, it would benefit the patient, avoiding the inconvenience of fasting and therefore needing to have blood drawn early in the day. Third, for individuals with diabetes, the risk of hypoglycaemia due to fasting would be minimised. Many countries are currently changing their guidelines towards a consensus on measuring a lipid profile for cardiovascular risk prediction in the nonfasting state, simplifying blood sampling for patients, laboratories, and clinicians worldwide.

Cardiovascular Benefits of Phenol-Enriched Virgin Olive Oils: New Insights from the Virgin Olive Oil and HDL Functionality (VOHF) Study

SCOPE

The main findings of the "Virgin Olive Oil and HDL Functionality" (VOHF) study and other related studies on the effect of phenol-enriched virgin olive oil (VOO) supplementation on cardiovascular disease are integrated in the present work.

METHODS AND RESULTS

VOHF assessed whether VOOs, enriched with their own phenolic compounds (FVOO) or with those from thyme (FVOOT), improve quantity and functionality of HDL. In this randomized, double-blind, crossover, and controlled trial, 33 hypercholesterolemic subjects received a control VOO (80 mg kg-1 ), FVOO (500 mg kg-1 ), and FVOOT (500 mg kg-1 ; 1:1) for 3 weeks. Both functional VOOs promoted cardioprotective changes, modulating HDL proteome, increasing fat-soluble antioxidants, improving HDL subclasses distribution, reducing the lipoprotein insulin resistance index, increasing endogenous antioxidant enzymes, protecting DNA from oxidation, ameliorating endothelial function, and increasing fecal microbial metabolic activity. Additional cardioprotective benefits were observed according to phenol source and content in the phenol-enriched VOOs. These insights support the beneficial effects of OO and PC from different sources.

CONCLUSION

Novel therapeutic strategies should increase HDL-cholesterol levels and enhance HDL functionality. The tailoring of phenol-enriched VOOs is an interesting and useful strategy for enhancing the functional quality of HDL, and thus, it can be used as a complementary tool for the management of hypercholesterolemic individuals.

Quantifying Atherogenic Lipoproteins: Current and Future Challenges in the Era of Personalized Medicine and Very Low Concentrations of LDL Cholesterol. A Consensus Statement from EAS and EFLM

BACKGROUND

The European Atherosclerosis Society-European Federation of Clinical Chemistry and Laboratory Medicine Consensus Panel aims to provide recommendations to optimize atherogenic lipoprotein quantification for cardiovascular risk management.

CONTENT

We critically examined LDL cholesterol, non-HDL cholesterol, apolipoprotein B (apoB), and LDL particle number assays based on key criteria for medical application of biomarkers. (a) Analytical performance: Discordant LDL cholesterol quantification occurs when LDL cholesterol is measured or calculated with different assays, especially in patients with hypertriglyceridemia >175 mg/dL (2 mmol/L) and low LDL cholesterol concentrations <70 mg/dL (1.8 mmol/L). Increased lipoprotein(a) should be excluded in patients not achieving LDL cholesterol goals with treatment. Non-HDL cholesterol includes the atherogenic risk component of remnant cholesterol and can be calculated in a standard nonfasting lipid panel without additional expense. ApoB more accurately reflects LDL particle number. (b) Clinical performance: LDL cholesterol, non-HDL cholesterol, and apoB are comparable predictors of cardiovascular events in prospective population studies and clinical trials; however, discordance analysis of the markers improves risk prediction by adding remnant cholesterol (included in non-HDL cholesterol) and LDL particle number (with apoB) risk components to LDL cholesterol testing. (c) Clinical and cost-effectiveness: There is no consistent evidence yet that non-HDL cholesterol-, apoB-, or LDL particle-targeted treatment reduces the number of cardiovascular events and healthcare-related costs than treatment targeted to LDL cholesterol.

SUMMARY

Follow-up of pre- and on-treatment (measured or calculated) LDL cholesterol concentration in a patient should ideally be performed with the same documented test method. Non-HDL cholesterol (or apoB) should be the secondary treatment target in patients with mild to moderate hypertriglyceridemia, in whom LDL cholesterol measurement or calculation is less accurate and often less predictive of cardiovascular risk. Laboratories should report non-HDL cholesterol in all standard lipid panels.

Circulating metabolomic profile can predict dyslipidemia in HIV patients undergoing antiretroviral therapy

BACKGROUND AND AIMS

Dyslipidemia in HIV-infected patients is unique and pathophysiologically associated with host factors, HIV itself and the use of antiretroviral therapy (ART). The use of nuclear magnetic resonance spectroscopy (NMR) provides additional data to conventional lipid measurements concerning the number of lipoprotein subclasses and particle sizes.

METHODS

To investigate the ability of lipoprotein profile, we used a circulating metabolomic approach in a cohort of 103 ART-naive HIV-infected patients, who were initiating non-nucleoside analogue transcriptase inhibitor (NNRTI)-based ART, and we subsequently followed up these patients for 36 months. Univariate and multivariate analyses were performed to evaluate the predictive power of NMR spectroscopy.

RESULTS

VLDL-metabolism (including VLDL lipid concentrations, sizes, and particle numbers), total triglycerides and lactate levels resulted in good classifiers of dyslipidemia (AUC 0.903). Total particles/HDL-P ratio was significantly higher in ART-associated dyslipidemia compared to ART-normolipidemia (p = 0.001). Large VLDL-Ps were positively associated with both LDL-triglycerides (ρ 0.682, p < 0.001) and lactate concentrations (ρ 0.416, p < 0.001), the last one a marker of mitochondrial low oxidative capacity.

CONCLUSIONS

Our data suggest that circulating metabolites have better predictive values for HIV/ART-related dyslipidemia onset than do the biochemical markers associated with conventional lipid measurements. NMR identifies changes in VLDL-P, lactate and LDL-TG as potential clinical markers of baseline HIV-dyslipidemia predisposition. Differences in circulating metabolomics, especially differences in particle size, are indicators of important derangements of mitochondrial function that are linked to ART-related dyslipidemia.

Evaluation of Carotid Plaque Neovascularization in Patients With Coronary Heart Disease on Contrast-Enhanced Ultrasonography

OBJECTIVES

To examine the repeatability of quantitative time-intensity curve analysis of neovascularization within carotid plaques with contrast-enhanced ultrasonography (US) and to investigate carotid plaque neovascularization in patients with coronary heart disease using contrast-enhanced US and the correlation between risk factors and acute coronary syndrome (ACS).

METHODS

Sixty patients with ACS and 60 with stable coronary artery disease (CAD) underwent conventional carotid and contrast-enhanced US, and plaque enhancement was observed and analyzed quantitatively. Carotid contrast-enhanced US was performed within 1 month of ACS occurrence. Interobserver and intraobserver variability of the measurements was assessed. The peak signal intensity was the maximum number of contrast microbubbles that local tissues could accumulate, reflecting the local microvascular density and representing the capillary volume.

RESULTS

The ACS group had higher low-density lipoprotein cholesterol (mean ± SD, 3.21 ± 0.75 versus 2.53 ± 0.71 mmol/L; P < .01) and high-sensitivity C-reactive protein (CRP; 3.76 ± 0.19 versus 2. 93 ± 0.15 mg/L; P < .01) levels than the stable CAD group. The proportion of soft plaques in the ACS group (81%) was higher than in the stable CAD group (53%). The proportion of plaque enhancement, peak signal intensity, and plaque-to-carotid lumen enhancement intensity ratio were higher in the ACS group than the stable CAD group. The peak signal intensity was correlated with the high-sensitivity CRP value. Logistic regression analyses indicated that age (65-74 years), high-sensitivity CRP, and enhancement intensity were correlated with the occurrence of ACS. The sensitivity and specificity of the peak signal intensity in carotid plaques were 80.0% and 88.3%, respectively (cutoff value, 9.97 dB; area under the receiver operating characteristic curve, 0.865). The time-intensity curve measurements had good repeatability.

CONCLUSIONS

Carotid plaque enhancement is a potential independent risk factor for ACS occurrence. These results illustrate the correlation of carotid plaque vulnerability with the coronary artery symptomatic state according to the common pathogenetic mechanism of atherosclerosis.

Discordance between lipoprotein particle number and cholesterol content: an update

PURPOSE OF REVIEW

The cholesterol content within atherogenic apolipoprotein-B (apoB) containing lipid particles is the center of consensus guidelines and clinicians' focus whenever evaluating a patient's risk for atherosclerotic cardiovascular disease. The pathobiology of atherosclerosis requires the retention of lipoprotein particles within the vascular intima over time followed by maladaptive inflammation resulting in plaque formation and rupture in some. The cholesterol content is widely variable within each particle creating either cholesterol-deplete or cholesterol-enriched particles. This variance in particle cholesterol content varies within and between individuals. Discordance analysis exploits this difference in cholesterol content of particles to demonstrate the differential significance of LDL-cholesterol (LDL-C) and non-HDL-C from measures of lipoprotein particle number in terms of assessing atherosclerotic cardiovascular disease risks.

RECENT FINDINGS

Three studies have added to the growing body of literature of discordance analysis. Despite wide variability of discordance cutoffs, baseline risk of atherosclerotic disease, and populations sampled, the conclusion remains the same: risk of atherosclerotic disease follows apoB lipid particle concentration rather than cholesterol content of lipid particles.

SUMMARY

In addition to traditional lipid fractions, assessments of atherogenic particle number should be strongly considered whenever assessing CVD risk in nontreated and treated individuals. There is a need for clinical trials that focus not only on the reduction in LDL-C but apoB, as well.

Update on the laboratory investigation of dyslipidemias

The role of the clinical laboratory is evolving to provide more information to clinicians to assess cardiovascular disease (CVD) risk and target therapy more effectively. Current routine methods to measure LDL-cholesterol (LDL-C), the Friedewald calculation, ultracentrifugation, electrophoresis and homogeneous direct methods have established limitations. Studies suggest that LDL and HDL size or particle concentration are alternative methods to predict future CVD risk. At this time there is no consensus role for lipoprotein particle or subclasses in CVD risk assessment. LDL and HDL particle concentration are measured by several methods, namely gradient gel electrophoresis, ultracentrifugation-vertical auto profile, nuclear magnetic resonance and ion mobility. It has been suggested that HDL functional assays may be better predictors of CVD risk. To assess the issue of lipoprotein subclasses/particles and HDL function as potential CVD risk markers robust, simple, validated analytical methods are required. In patients with small dense LDL particles, even a perfect measure of LDL-C will not reflect LDL particle concentration. Non-HDL-C is an alternative measurement and includes VLDL and CM remnant cholesterol and LDL-C. However, apolipoprotein B measurement may more accurately reflect LDL particle numbers. Non-fasting lipid measurements have many practical advantages. Defining thresholds for treatment with new measurements of CVD risk remain a challenge. In families with genetic variants, ApoCIII and lipoprotein (a) may be additional risk factors. Recognition of familial causes of dyslipidemias and diagnosis in childhood will result in early treatment. This review discusses the limitations in current laboratory technologies to predict CVD risk and reviews the evidence for emergent approaches using newer biomarkers in clinical practice.

Apolipoprotein B is associated with carotid atherosclerosis progression independent of individual cholesterol measures in a 9-year prospective study of Multi-Ethnic Study of Atherosclerosis participants

BACKGROUND

High blood cholesterol contributes to atherosclerosis, yet reliance on the lipid panel alone may mischaracterize individuals with elevated lipoprotein particle numbers.

OBJECTIVE

The aim of the article was to determine whether elevated lipoprotein or apolipoprotein measures are associated with carotid atherosclerosis and plaque progression independent of cardiovascular (CV) risk factors including standard lipids in a subcohort of 2228 Multi-Ethnic Study of Atherosclerosis participants.

METHODS

Ultrasonography assessed carotid artery plaque and common carotid intima-media thickness (cIMT) at baseline and after a median period of 9.4 years. Nuclear magnetic resonance spectroscopy estimated lipoprotein particle concentrations. Apolipoprotein B (ApoB) and apolipoprotein A-I were measured using an automated immunoassay. Regression analysis determined associations of apolipoprotein and lipoprotein measurements with cIMT and relative risk regression determined associations with carotid plaque progression.

RESULTS

After adjustment for typical CV risk factors, individuals in top quartiles of ApoB, ApoB/apolipoprotein A-I, low-density lipoprotein particles (LDL-P), small LDL-P, and total LDL-P/high-density lipoprotein (HDL) particles showed similar risks of carotid plaque and cIMT progression as LDL-C, non-HDL cholesterol (HDL-C), total cholesterol (TC), and TC/HDL-C. A significant association with plaque progression remained in the top ApoB quartile after further adjustment for LDL-C (P = .02) or TC + HDL-C (P = .04), but was nonsignificant when adjusted for all lipid covariates (P = .086). Those in the top quartile of small LDL-P concentrations showed greater cIMT progression than those in the referent after adjustment for LDL-C, but this was nonsignificant after adjustment for TC + HDL-C.

CONCLUSION

When coupled with evidence that apolipoprotein testing identifies lipid-lipoprotein discordance, these findings suggest that ApoB and small LDL-P provide atherosclerosis risk information that is not revealed by typical CV risk factors.

LDL subfractions are associated with incident cardiovascular disease in the Malmö Prevention Project Study

BACKGROUND AND AIMS

After assessing the risk for cardiovascular disease (CVD) based on traditional risk factors, decisions concerning lipid lowering therapy might remain uncertain. To investigate whether lipoprotein subfraction levels could aid these decisions, we assessed the association between lipoprotein subfractions and CVD, after adjustment for traditional risk factors including standard lipids.

METHODS

Using a case-cohort design, participants were randomly drawn from the Malmö Prevention Project (MPP), a population-based prospective study of 18,240 participants, and supplemented with additional incident CVD events (5764 participants, 1784 CVD events).

RESULTS

Low density lipoprotein particle number (LDL-P) and individual subfractions ranging in size from very-small to large were associated with CVD (continuous p value (p_cont) < 0.001) while adjusting for age, sex, hypertension, smoking, and diabetes. After further adjustment for LDL-C, HDL-C, and triglycerides, very small LDL subfraction (b) (LDL-VS (b)) remained associated with CVD (HR = 1.23, 95% CI, 1.06 to 1.43 for top vs. bottom quartile, p_cont = 0.03). Among participants with low/intermediate risk [without diabetes and with LDL-C <3.36 mmol/L (<130 mg/dL)], the fully adjusted HR for LDL-small (top vs. bottom quartile) was 1.48 (95% CI 1.02 to 2.17, p_cont = 0.03). Among those with very-high risk (>20% 10-year risk of CVD), LDL-VS(a) and LDL-VS(b) were associated with CVD in fully adjusted models (HR = 1.37, 95% CI 1.12 to 1.67 and HR = 1.28, 95% CI 1.07 to 1.53, respectively, p_cont≤0.03).

CONCLUSIONS

Smaller LDL particles are associated with incident CVD independently of traditional risk factors, including standard lipids, in participants with low/intermediate and very-high risk, who might benefit from improved risk assessment.

Genetic associations with lipoprotein subfraction measures differ by ethnicity in the multi-ethnic study of atherosclerosis (MESA)

A recent genome-wide association study associated 62 single nucleotide polymorphisms (SNPs) from 43 genomic loci, with fasting lipoprotein subfractions in European–Americans (EAs) at genome-wide levels of significance across three independent samples. Whether these associations are consistent across ethnicities with a non-European ancestry is unknown. We analyzed 15 lipoprotein subfraction measures, on 1677 African–Americans (AAs), 1450 Hispanic–Americans (HAs), and 775 Chinese–Americans (CHN) participating in the multi-ethnic study of atherosclerosis (MESA). Genome-wide data were obtained using the Affymetrix 6.0 and Illumina HumanOmni chips. Linear regression models between genetic variables and lipoprotein subfractions were adjusted for age, gender, body mass index, smoking, study center, and genetic ancestry (based on principal components), and additionally adjusted for Mexican/Non-Mexican status in HAs. A false discovery rate correction was applied separately within the results for each ethnicity to correct for multiple testing. Power calculations revealed that we did not have the power for SNP-based measures of association, so we analyzed phenotype-specific genetic risk scores (GRSs), constructed as in the original genome-wide analysis. We successfully replicated all 15 GRS–lipoprotein associations in 2527 EAs. Among the 15 significant GRS–lipoprotein associations in EAs, 11 were significant in AAs, 13 in HAs, and 1 in CHNs. Further analyses revealed that ethnicity differences could not be explained by differences in linkage disequilibrium, lipid lowering drugs, diabetes, or gender. Our study emphasizes the importance of ethnicity (here indexing genetic ancestry) in genetic risk for CVD and highlights the need to identify ethnicity-specific genetic variants associated with CVD risk.

Lipoprotein Biomarkers and Risk of Cardiovascular Disease: A Laboratory Medicine Best Practices (LMBP) Systematic Review

BACKGROUND

Controversy exists about the incremental utility of nontraditional lipid biomarkers [e.g., apolipoprotein (apo) B, apo A-I, and non-HDL-C] in improving cardiovascular disease (CVD) risk prediction when added to a conventional model of traditional risk factors (e.g., total cholesterol, LDL cholesterol, HDL cholesterol, sex, age, smoking status, and blood pressure). Here we present a systematic review that was conducted to assess the use of nontraditional lipid biomarkers including apo B, apo A-I, apo B/A-I ratio, and non-HDL-C in improving CVD risk prediction after controlling for the traditional risk factors in populations at risk for cardiovascular events.

CONTENT

This systematic review used the Laboratory Medicine Best Practices (LMBP™) A-6 methods. A total of 9 relevant studies published before and including July 2015 comprised the evidence base for this review. Results from this systematic review indicated that after the adjustment for standard nonlipid and lipid CVD risk factors, nontraditional apolipoprotein biomarkers apo B (overall effect = relative risk: 1.31; 95% CI, 1.22-1.40; 4 studies) and apo B/apo A-I ratio (overall effect = relative risk: 1.31; 95% CI, 1.11-1.38; 7 studies) resulted in significant improvement in long-term CVD risk assessment.

SUMMARY

Available evidence showed that nontraditional lipid biomarkers apo B and apo B/apo I ratio can improve the risk prediction for cardiovascular events after controlling for the traditional risk factors for the populations at risk. However, because of insufficient evidence, no conclusions could be made for the effectiveness of apo A-I and non-HDL-C lipid markers to predict the CVD events, indicating a need for more research in this field.

HDLs in crises

PURPOSE OF REVIEW

The clinical utility of HDLs has been scrutinized upon the publication of Mendelian randomization studies showing no effect of HDL-cholesterol (HDL-C) modifying variants on cardiovascular disease (CVD) outcome. The failures of randomized controlled HDL-C-directed intervention trials have further fueled this skepticism. This general criticism originates from oversimplification that has equated 'HDL-C' with 'HDL' and misconceived both as the 'good cholesterol'.

RECENT FINDINGS

HDL particles are heterogeneous and carry hundreds of different lipids, proteins, and microRNAs. Many of them but not cholesterol, that is, HDL-C, contributes to the multiple protective functions of HDLs that probably evolved to manage potentially life-threatening crises. Inflammatory processes modify the composition of HDL particles as well as their individual protein and lipid components, and, as a consequence, also their functionality. Gain of dominant-negative functions makes dysfunctional HDL a part rather than a solution of the endangering situation. Quantification of HDL particle numbers, distinct proteins or lipids, and modifications thereof as well as bioassays of HDL functionality are currently explored toward their diagnostic performance in risk prediction and monitoring of treatment response.

SUMMARY

Any successful clinical exploitation of HDLs will depend on the identification of the most relevant (dys)functions and their structural correlates. Stringent or prioritized structure-(dys)function relationships may provide biomarkers for better risk assessment and monitoring of treatment response. The most relevant agonists carried by either functional or dysfunctional HDLs as well as their cellular responders are interesting targets for drug development.

Polyphenol rich olive oils improve lipoprotein particle atherogenic ratios and subclasses profile: A randomized, crossover, controlled trial

SCOPE

Lipoprotein particle measures performed by nuclear magnetic resonance (NMR), and associated ratios, may be better markers for atherosclerosis risk than conventional lipid measures. The effect of two functional olive oils, one enriched with its polyphenols (FVOO, 500 ppm), and the other (FVOOT) with them (250 ppm) and those of thyme (250 ppm), versus a standard virgin olive oil (VOO), on lipoprotein particle atherogenic ratios and subclasses profiles was assessed.

METHODS AND RESULTS

In a randomized, double-blind, crossover, controlled trial, 33 hypercholesterolemic individuals received 25 mL/day of VOO, FVOO, and FVOOT. Intervention periods were of 3 weeks separated by 2-week washout periods. Lipoprotein particle counts and subclasses were measured by NMR. Polyphenols from olive oil and thyme modified the lipoprotein subclasses profile and decreased the total LDL particle/total HDL particle (HDL-P), small HDL/large HDL, and HDL-cholesterol/HDL-P ratios, and decreased the lipoprotein insulin resistance index (LP-IR) (p < 0.05).

CONCLUSION

Olive oil polyphenols, and those from thyme provided benefits on lipoprotein particle atherogenic ratios and subclasses profile distribution. Polyphenol-enriched olive oil is a way of increasing the olive oil healthy properties while consuming the same amount of fat, as well as a useful and complementary tool for the management of cardiovascular risk individuals.

Associations between intensive diabetes therapy and NMR-determined lipoprotein subclass profiles in type 1 diabetes

Our objective is to define differences in circulating lipoprotein subclasses between intensive versus conventional management of type 1 diabetes during the randomization phase of the Diabetes Control and Complications Trial (DCCT). NMR-determined lipoprotein subclass profiles (NMR-LSPs), which estimate molar subclass concentrations and mean particle diameters, were determined in 1,294 DCCT subjects after a median of 5 years (interquartile range: 4-6 years) of randomization to intensive or conventional diabetes management. In cross-sectional analyses, we compared standard lipids and NMR-LSPs between treatment groups. Standard total, LDL, and HDL cholesterol levels were similar between randomization groups, while triglyceride levels were lower in the intensively treated group. NMR-LSPs showed that intensive therapy was associated with larger LDL diameter (20.7 vs. 20.6 nm, P = 0.01) and lower levels of small LDL (median: 465 vs. 552 nmol/l, P = 0.007), total IDL/LDL (mean: 1,000 vs. 1,053 nmol/l, P = 0.01), and small HDL (mean: 17.3 vs. 18.6 μmol/l, P < 0.0001), the latter accounting for reduced total HDL (mean: 33.8 vs. 34.8 μmol/l, P = 0.01). In conclusion, intensive diabetes therapy was associated with potentially favorable changes in LDL and HDL subclasses in sera. Further research will determine whether these changes contribute to the beneficial effects of intensive diabetes management on vascular complications.