Assessing the Accuracy of Estimated Lipoprotein(a) Cholesterol and Lipoprotein(a)-Free Low-Density Lipoprotein Cholesterol.

Background Accurate measurement of the cholesterol within lipoprotein(a) (Lp[a]-C) and its contribution to low-density lipoprotein cholesterol (LDL-C) has important implications for risk assessment, diagnosis, and treatment of atherosclerotic cardiovascular disease, as well as in familial hypercholesterolemia. A method for estimating Lp(a)-C from particle number using fixed conversion factors has been proposed (Lp[a]-C from particle number divided by 2.4 for Lp(a) mass, multiplied by 30% for Lp[a]-C). The accuracy of this method, which theoretically can isolate "Lp(a)-free LDL-C," has not been validated. Methods and Results In 177 875 patients from the VLDbL (Very Large Database of Lipids), we compared estimated Lp(a)-C and Lp(a)-free LDL-C with measured values and quantified absolute and percent error. We compared findings with an analogous data set from the Mayo Clinic Laboratory. Error in estimated Lp(a)-C and Lp(a)-free LDL-C increased with higher Lp(a)-C values. Median error for estimated Lp(a)-C <10 mg/dL was -1.9 mg/dL (interquartile range, -4.0 to 0.2); this error increased linearly, overestimating by +30.8 mg/dL (interquartile range, 26.1-36.5) for estimated Lp(a)-C ≥50 mg/dL. This error relationship persisted after stratification by overall high-density lipoprotein cholesterol and high-density lipoprotein cholesterol subtypes. Similar findings were observed in the Mayo cohort. Absolute error for Lp(a)-free LDL-C was +2.4 (interquartile range, -0.6 to 5.3) for Lp(a)-C<10 mg/dL and -31.8 (interquartile range, -37.8 to -26.5) mg/dL for Lp(a)-C≥50 mg/dL. Conclusions Lp(a)-C estimations using fixed conversion factors overestimated Lp(a)-C and subsequently underestimated Lp(a)-free LDL-C, especially at clinically relevant Lp(a) values. Application of inaccurate Lp(a)-C estimations to correct LDL-C may lead to undertreatment of high-risk patients.

Changes in lipoprotein subfractions following menopause in the Longitudinal Study of Adult Health (ELSA-Brasil).

INTRODUCTION: It is unclear how aging and menopause-induced lipid changes contribute to the elevated cardiovascular risk in menopausal women. We examined the association between lipid profiles and menopausal status and duration of menopause in the Longitudinal Study of Adult Health (ELSA-Brasil). METHODS: This is a cross-sectional analysis of baseline data from women in the ELSA-Brasil, stratified by duration of menopause into 5 groups: pre-menopause, <2 years, 2-5.9 years, 6-9.9 years and ≥10 years of menopause, excluding menopause <40 years or of non-natural cause; also excluded were women using lipid-lowering drugs or hormone replacement. Comparisons were performed using ANOVA with Bonferroni correction. Associations of menopause categories and time since menopause with lipid variables obtained by vertical auto-profile were tested using multiple linear regression. RESULTS: From 1916 women, postmenopausal groups had unadjusted higher total cholesterol, LDL-c, real LDL-c, IDL-c, VLDL-c, triglycerides, non-HDL-c, VLDL3-c, triglyceride-rich lipoprotein remnants (TRL-c) and buoyant LDL-c concentrations than pre-menopausal women, with no difference among postmenopausal groups. In multiple linear regression, duration of menopause <2 years was significantly associated with TRL-c [7.21 mg/dL (95% CI 3.59-10.84)] and VLDL3-c [2.43 mg/dL (95%CI 1.02-3.83)]. No associations of menopausal categories with HDL-c or LDL-c subfractions were found, and nor were associations of time since menopause with lipid subfractions. CONCLUSIONS: In a large sample of Brazilian women, deterioration of the lipid profile following menopause was confirmed, which could contribute to the increased cardiovascular risk. Our findings suggest a postmenopausal elevation in triglyceride-rich lipoprotein remnants. How lipoprotein subfractions change after the onset of menopause warrants investigation in studies with appropriate designs.

High-density Lipoprotein-cholesterol Subfractions and Coronary Artery Calcium: The ELSA-Brasil Study.

BACKGROUND: Although elevated high-density lipoprotein cholesterol (HDL-C) is considered protective against atherosclerotic cardiovascular disease, no causal relationship has been demonstrated. HDL-C comprises a group of different subfractions that might have different effects on atherosclerosis. Our objective was to investigate the association between HDL-C subfractions with the coronary artery calcium (CAC) score. METHODS: We included 3,674 (49.8 ± 8.3 years, 54% women) participants from the ELSA-Brasil study who had no prior history of CVD and were not currently using lipid-lowering medications. We measured the fasting lipoprotein cholesterol fractions (in mmol/l) by a zonal ultracentrifugation method (VAP). We analyzed the independent predictive values of total HDL-C, HDL2-C, and HDL3-C subfractions and in the HDL2-C/HDL3-C ratio using linear regression to predict Ln(CAC+1) and logistic regression to predict the presence of CAC. RESULTS: Overall 912 (24.8%) of the participants had CAC>0, and 294 (7.7%) had CAC>100. The mean total HDL-C, HDL2-C, and HDL3-C were: 1.42 ± 0.37, 0.38 ± 0.17 and 1.03 ± 0.21 mmol/l, respectively. Individuals with CAC>0 had lower levels of total HDL-C as well as of each subfraction (p < 0.001). When adjusted for age, gender, smoking, hypertension, alcohol use, physical activity, and LDL-C, we observed an inverse association between HDL-C and its subfractions and CAC (p < 0.05). However, by adding triglycerides in the adjustment, neither total HDL-C nor its subfractions remained independently associated with the presence or extent of CAC. CONCLUSION: In this cross-sectional analysis, neither the total HDL-C nor its subfractions (HDL2-C and HDL3-C, as well as HDL2-C/HDL3-C ratio) measured by VAP are independently associated with the presence or extent of coronary calcification.

Characterization of lipoprotein profiles in patients with hypertriglyceridemic Fredrickson-Levy and Lees dyslipidemia phenotypes: the Very Large Database of Lipids Studies 6 and 7.

INTRODUCTION: The association between triglycerides (TG) and cardiovascular diseases is complex. The classification of hypertriglyceridemic (HTG) phenotypes proposed by Fredrickson, Levy and Lees (FLL) helps inform treatment strategies. We aimed to describe levels of several lipoprotein variables from individuals with HTG FLL phenotypes from the Very Large Database of Lipids. MATERIAL AND METHODS: We included fasting samples from 979,539 individuals from a contemporary large study population of US adults. Lipids were directly measured by density-gradient ultracentrifugation using the Vertical Auto Profile test while TG levels were measured in whole plasma using the Abbott ARCHITECT C-8000 system. Hyperchylomicronemic (Hyper-CM) and non-chylomicronemic (non-CM) phenotypes were defined using computationally derived models. Individuals with FLL type IIa phenotype were excluded. Distributions of lipid variables were compared using medians and Kruskal-Wallis test. RESULTS: A total of 11.9% (n = 116,925) of individuals met criteria for HTG FLL phenotypes. Those with hyper-CM phenotypes (n = 5, < 0.1% of population) had two-fold higher TG levels compared with non-chylomicronemic (non-CM) individuals (11.9% of population) (p < 0.001). Type IIb individuals had the highest non-HDL-C levels (median 242 mg/dl). Cholesterol in large VLDL1+2 particles was higher than in small VLDL3 particles in all phenotypes except FLL type III. Hyper-CM phenotypes had significantly lower HDL-C levels but greater HDL2/HDL3-C ratio compared to non-CM phenotypes. Cholesterol content of the lipoprotein (a) peak was significantly higher in the hyper-CM groups compared to non-CM phenotypes (p < 0.0001). CONCLUSIONS: This observational hypothesis-generating study provides insight into the complexity of lipid metabolism in HTG phenotypes, including less traditional lipid measures such as LDL density, HDL subclasses and Lp(a)-C.

Comparability of Lipoprotein Particle Number Concentrations Across ES-DMA, NMR, LC-MS/MS, Immunonephelometry, and VAP: In Search of a Candidate Reference Measurement Procedure for apoB and non-HDL-P Standardization.

BACKGROUND: Despite the usefulness of standard lipid parameters for cardiovascular disease risk assessment, undiagnosed residual risk remains high. Advanced lipoprotein testing (ALT) was developed to provide physicians with more predictive diagnostic tools. ALT methods separate and/or measure lipoproteins according to different parameters such as size, density, charge, or content, and equivalence of results across methods has not been demonstrated. METHODS: Through a split-sample study, 25 clinical specimens (CSs) were assayed in 10 laboratories before and after freezing using the major ALT methods for non-HDL particles (non-HDL-P) or apolipoprotein B-100 (apoB-100) measurements with the intent to assess their comparability in the current state of the art. RESULTS: The overall relative standard deviation (CV) of non-HDL-P and apoB-100 concentrations measured by electrospray differential mobility analysis, nuclear magnetic resonance, immunonephelometry, LC-MS/MS, and vertical autoprofile in the 25 frozen CSs was 14.1%. Within-method comparability was heterogeneous, and CV among 4 different LC-MS/MS methods was 11.4% for apoB-100. No significant effect of freezing and thawing was observed. CONCLUSIONS: This study demonstrates that ALT methods do not yet provide equivalent results for the measurement of non-HDL-P and apoB-100. The better agreement between methods harmonized to the WHO/IFCC reference material suggests that standardizing ALT methods by use of a common commutable calibrator will improve cross-platform comparability. This study provides further evidence that LC-MS/MS is the most suitable candidate reference measurement procedure to standardize apoB-100 measurement, as it would provide results with SI traceability. The absence of freezing and thawing effect suggests that frozen serum pools could be used as secondary reference materials.

Diabetes alters the association between high-density lipoprotein subfractions and carotid intima-media thickness: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

INTRODUCTION: High-density lipoprotein cholesterol comprises a group of heterogeneous subfractions that might have differential effects on atherosclerosis. Moreover, prior investigations suggest that the presence of diabetes (T2D) modifies the impact of some subfractions on atherosclerosis. In this study, we aimed to evaluate the association between high-density lipoprotein cholesterol subfractions and carotid intima-media thickness in the baseline assessment of the Brazilian Longitudinal Study of Adult Health participants from the São Paulo investigation centre. METHODS: We evaluated 3930 individuals between 35 and 74 years without previous cardiovascular disease not using lipid-lowering drugs. High-density lipoprotein cholesterol subfractions (HDL2-C and HDL3-C) were measured by vertical ultracentrifugation (vertical auto profile). The relationship between each high-density lipoprotein cholesterol subfraction and carotid intima-media thickness was analysed by multiple linear regression models. RESULTS: Total high-density lipoprotein cholesterol, as well as HDL2-C and HDL3-C, was negatively associated with carotid intima-media thickness after adjustment for demographic data (all p < 0.001) and traditional risk factors (all p < 0.05). When stratified by T2D status, the HDL2-C/HDL3-C ratio showed a negative association with carotid intima-media thickness in participants with T2D ( p = 0.032), even after fully controlling for confounding variables, including total high-density lipoprotein cholesterol. CONCLUSION: HDL2-C, HDL3-C and HDL2/HDL3-C ratio are inversely associated with carotid intima-media thickness after adjustment for traditional risk factors. Association of the HDL2-C/HDL3-C ratio is modified by the presence of diabetes, being more pronounced in diabetic individuals.

Association between high-density lipoprotein subfractions and low-grade inflammation, insulin resistance, and metabolic syndrome components: The ELSA-Brasil study.

BACKGROUND: High-density lipoprotein cholesterol (HDL-C) can be divided into subfractions, which may have variable effects in atherogenesis. The results about the association between HDL-C subfractions and risk factors for cardiovascular disease are mixed. OBJECTIVE: The objective of this study was to analyze the association between HDL-C subfractions and each metabolic syndrome component, homeostasis model assessment-estimated insulin resistance (HOMA-IR) and C-reactive protein (CRP). METHODS: Four thousand five hundred thirty-two individuals between 35 and 74 years old without previous manifest cardiovascular disease not using fibrates were enrolled. HDL-C subfractions were separated by vertical ultracentrifugation (vertical auto profile-in mg/dL) into HDL2-C and HDL3-C. HDL2-C/HDL3-C ratio, HOMA-IR, and high-sensitivity CRP were also included in the analysis. RESULTS: Mean age of participants was 51 ± 9 years, and 54.8% were women. In univariate analysis, HDL-C, HDL2-C, and HDL3-C were all inversely associated with each of the metabolic syndrome defining factors, HOMA-IR values, and serum CRP. We also observed a negative association between HDL2-C/HDL3-C ratio with the variables aforementioned even after adjusting for smoking, alcohol use, physical activity, and HDL-C levels (P < .01). CONCLUSION: HDL-C and its subfractions (HDL2-C and HDL3-C) are inversely associated with the defining features of metabolic syndrome, insulin resistance, and systemic inflammation. In addition, the HDL2-C/HDL3-C ratio measured by vertical auto profile is significantly associated with the former factors even after comprehensive adjustment for HDL-C and other confounding variables.

Association of low-density lipoprotein pattern with mortality after myocardial infarction: Insights from the TRIUMPH study.

BACKGROUND: Studies of incident coronary heart disease risk within low-density lipoprotein (LDL) subclass (small, dense vs large, buoyant) have shown mixed results. No prospective cohort study has examined the association of small, dense, or large, buoyant LDL with mortality after myocardial infarction (MI). OBJECTIVE: The objective of the study was to examine association of LDL pattern after MI and death. METHODS: In 2476 patients hospitalized for MI, LDL pattern (A [large, buoyant], A/B [mixed], and B [small, dense]) was established by ultracentrifugation using Vertical Auto Profile. Using time-to-event analysis, we examined the association with 5-year mortality within LDL patterns, after adjusting for important patient and treatment characteristics. We additionally adjusted for LDL cholesterol (LDL-C) and triglyceride levels and used directly measured LDL-C and non-high-density lipoprotein cholesterol as exposures. RESULTS: Patterns A, A/B, and B were present in 39%, 28%, and 33% of patients, respectively, with incident rates (per 1000 patient-years) of 50, 34, and 24 for all-cause and 24, 19, and 10 for CV mortality. The hazard ratios (95% confidence interval) with LDL patterns A/B and B compared with pattern A were 0.77 (0.61, 0.99) and 0.67 (0.51, 0.88) for all-cause, 0.94 (0.67, 1.33) and 0.69 (0.46, 1.03) for cardiovascular, and 0.64 (0.45, 0.91) and 0.65 (0.45, 0.93) for noncardiovascular mortalities, respectively. Results were similar when further adjusted for LDL-C and triglycerides, or with LDL-C and non-high-density lipoprotein cholesterol as exposures. CONCLUSION: Compared with LDL pattern A, pattern B was significantly associated with reduced all-cause and non-CV mortalities with a trend for lower CV mortality after MI, independent of LDL-C and triglycerides.

Impact of Subclinical Hypothyroidism on Cardiometabolic Biomarkers in Women.

CONTEXT: Whether subclinical hypothyroidism (SCH) is associated with cardiometabolic abnormalities is uncertain. OBJECTIVE: To examine diverse cardiometabolic biomarkers across euthyroid, SCH, and overt hypothyroidism (HT) in women free of cardiovascular disease (CVD). DESIGN: Cross-sectional adjusted associations for lipids, lipoprotein subclasses, lipoprotein insulin resistance score, inflammatory, coagulation, and glycemic biomarkers by ANCOVA for thyroid categories or TSH quintiles on a Women's Health Study subcohort. SETTING: Outpatient. PATIENTS OR OTHER PARTICIPANTS: Randomly sampled 3,914 middle-aged and older women for thyroid function analysis (thyroid-stimulating hormone [TSH], free T4), of whom 3,321 were not on lipid lowering therapy. INTERVENTION: None. MAIN OUTCOME MEASURE: Associations of SCH and HT with cardiometabolic markers. RESULTS: Going from euthyroid to HT, the lipoprotein subclasse profiles were indicative of insulin resistance [respective values and p for trend]: larger VLDL size (nm)[51.5 (95%CI51.2, 51.8) to 52.9 (51.8, 54.1) p=0.001]; higher LDL particles concentration (nmol/L)[1283 (95%CI1267, 1299) to 1358 (1298, 1418) p=0.004] and smaller LDL size. There was worsening lipoprotein insulin resistance score from euthyroid 49.2 (95%CI 48.3, 50.2) to SCH 52.1 (95%CI 50.1, 54.0), and HT 52.1 (95%CI 48.6, 55.6), p for trend 0.008. Of the other biomarkers, SCH and HT were associated with higher hs-CRP and HbA1c. For increasing TSH quintiles results were overall similar. CONCLUSIONS: In apparently healthy women, SCH cardiometabolic profiles indicated worsening insulin resistance and higher CVD risk markers compared with euthyroid individuals, despite similar LDL and total cholesterol. These findings suggest that cardiometabolic risk may increase early in the progression towards SCH and OH.

Accuracy of low-density lipoprotein cholesterol estimation at very low levels.

BACKGROUND: As the approach to low-density lipoprotein cholesterol (LDL-C) lowering becomes increasingly intensive, accurate assessment of LDL-C at very low levels warrants closer attention in individualized clinical efficacy and safety evaluation. We aimed to assess the accuracy of LDL-C estimation at very low levels by the Friedewald equation, the de facto clinical standard, and compare its accuracy with a novel, big data-derived LDL-C estimate. METHODS: In 191,333 individuals with Friedewald LDL-C < 70 mg/dL, we compared the accuracy of Friedewald and novel LDL-C values in relation to direct measurements by Vertical Auto Profile ultracentrifugation. We examined differences (estimate minus ultracentrifugation) and classification according to levels initiating additional safety precautions per clinical practice guidelines. RESULTS: Friedewald values were less than ultracentrifugation measurement, with a median difference (25th to 75th percentile) of -2.4 (-7.4 to 0.6) at 50-69 mg/dL, -7.0 (-16.2 to -1.2) at 25-39 mg/dL, and -29.0 (-37.4 to -19.6) at < 15 mg/dL. The respective values by novel estimation were -0.1 (-1.5 to 1.3), -1.1 (-2.5 to 0.3), and -2.7 (-4.9 to 0.0) mg/dL. Among those with Friedewald LDL-C < 15, 15 to < 25, and 25 to < 40 mg/dL, the classification was discordantly low in 94.9%, 82.6%, and 59.9% of individuals as compared with 48.3%, 42.4%, and 22.4% by novel estimation. CONCLUSIONS: Estimation of even lower LDL-C values (by Friedewald and novel methods) is even more inaccurate. More often than not, a Friedewald value < 40 mg/dL is underestimated, which translates into unnecessary safety alarms that could be reduced in half by estimation using our novel method.

Greater remnant lipoprotein cholesterol reduction with pitavastatin compared with pravastatin in HIV-infected patients.

OBJECTIVE: Cardiovascular disease (CVD) is a leading cause of morbidity and mortality in those with HIV. An emerging CVD risk factor is triglyceride-rich remnant lipoprotein cholesterol (RLP-C: the sum of intermediate-density lipoprotein and very low-density lipoprotein cholesterol). The effects of statin therapy on lipoprotein subfractions, including RLP-C, in HIV dyslipidemia are unknown. METHODS: This is a post hoc analysis of the randomized INTREPID trial (NCT 01301066) comparing pitavastatin 4 mg daily vs. pravastatin 40 mg daily in study participants with HIV. We measured apolipoproteins AI and B and lipoprotein cholesterol subfractions separated by density gradient ultracentrifugation at baseline and 12 weeks. We compared changes in atherogenic subfractions over 12 weeks in INTREPID participants using analysis of covariance. RESULTS: Lipoprotein subfraction data were available for 213 study participants (pitavastatin n = 104, pravastatin n = 109). Baseline characteristics were similar between treatment groups. Reductions in RLP-C were significantly greater in the pitavastatin group compared with pravastatin group (-11.6 mg/dl vs. -8.5 mg/dl; P = 0.01). Similarly, ratios of risk [apolipoproteins B/apolipoproteins AI, total cholesterol/high-density lipoprotein cholesterol (HDL-C)] showed greater reductions with pitavastatin (P < 0.05). There were no differences in changes in HDL-C, HDL-C subfractions or lipoprotein(a) cholesterol levels. CONCLUSION: In patients with HIV, pitavastatin 4 mg/dl lowered both RLP-C and established apolipoprotein and lipid risk ratios more so than pravastatin 40 mg/dl. The impact of RLP-C reduction on CVD in HIV dyslipidemic patients merits further study.

Remnant Lipoprotein Cholesterol and Incident Coronary Heart Disease: The Jackson Heart and Framingham Offspring Cohort Studies.

BACKGROUND: Remnant lipoproteins (RLPs), the triglyceride-enriched precursors to low-density lipoprotein, are an emerging risk factor for coronary heart disease (CHD). We sought to determine the association of RLP cholesterol (RLP-C) levels with incident CHD in 2 diverse, prospective, longitudinal observational US cohorts. METHODS AND RESULTS: We analyzed cholesterol levels from serum lipoprotein samples separated via density gradient ultracentrifugation in 4114 US black participants (mean age 53.8 years, 64% women) from the Jackson Heart Study and a random sample of 818 predominantly white participants (mean age 57.3 years, 52% women) from the Framingham Offspring Cohort Study. Multivariable-adjusted hazard ratios (HRs) for RLP-C (the sum of very low-density lipoprotein3 cholesterol and intermediate-density lipoprotein cholesterol) were derived to estimate associations with incident CHD events consisting of myocardial infarction, CHD death, and revascularizations for each cohort separately and as a combined population. There were 146 CHD events in the combined population. After adjustments for age, sex, body mass index, smoking, blood pressure, diabetes, and lipid-lowering therapy for the combined population, RLP-C (HR 1.23 per 1-SD increase, 95% CI 1.06-1.42, P<0.01) and intermediate-density lipoprotein cholesterol (HR 1.26 per 1-SD increase, 95% CI 1.08-1.47, P<0.01) predicted CHD during an 8-year follow-up. Associations were attenuated by high-density lipoprotein cholesterol and ultimately lost significance with inclusion of real low-density lipoprotein cholesterol, which excludes Lp(a) and IDL cholesterol fractions. Similar associations were seen in multivariable analyses within each cohort. CONCLUSION: RLP-C levels are predictive of incident CHD in this diverse group of primary prevention subjects. Interventions aimed at reducing RLP-C to prevent CHD warrant further intensive investigation. CLINICAL TRIAL REGISTRATION: URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00415415.

Effect of alirocumab on specific lipoprotein non-high-density lipoprotein cholesterol and subfractions as measured by the vertical auto profile method: analysis of 3 randomized trials versus placebo.

BACKGROUND: The effect of alirocumab on potentially atherogenic lipoprotein subfractions was assessed in a post hoc analysis using the vertical auto profile (VAP) method. METHODS: Patients from three Phase II studies with low-density lipoprotein cholesterol (LDL-C) ≥ 2.59 mmol/L (100 mg/dL) at baseline on stable statin therapy were randomised to receive subcutaneous alirocumab 50-150 mg every 2 weeks (Q2W) or 150-300 mg every 4 weeks (according to study) or placebo for 8-12 weeks. Samples from patients treated with alirocumab 150 mg Q2W (n = 74; dose common to all three trials) or placebo (n = 71) were analysed by VAP. Percent change in lipoprotein subfractions with alirocumab vs. placebo was analysed at Weeks 6, 8 or 12 using analysis of covariance. RESULTS: Alirocumab significantly reduced LDL-C and the cholesterol content of subfractions LDL1, LDL2 and LDL3+4. Significant reductions were also observed in triglycerides, apolipoproteins CII and CIII and the cholesterol content of very low-density, intermediate-density, and remnant lipoproteins. CONCLUSION: Alirocumab achieved reductions across a spectrum of atherogenic lipoproteins in patients receiving background statin therapy. TRIAL REGISTRATION: Clinicaltrials.gov identifiers: NCT01288443, NCT01288469, NCT01266876.

The utility of the apolipoprotein A1 remnant ratio in predicting incidence coronary heart disease in a primary prevention cohort: The Jackson Heart Study.

BACKGROUND: Dyslipidemia plays a significant role in the progression of cardiovascular disease. The apolipoprotein (apo) A1 remnant ratio (apo A1/VLDL3-C + IDL-C) has recently been shown to be a strong predictor of death/myocardial infarction risk among women >50 years undergoing angiography. However, whether this ratio is associated with coronary heart disease risk among other populations is unknown. We evaluated the apo A1 remnant ratio and its components for coronary heart disease incidence. DESIGN: Observational. METHODS: Participants (N = 4722) of the Jackson Heart Study were evaluated. Baseline clinical characteristics and lipoprotein subfractions (Vertical Auto Profile method) were collected. Cox hazard regression analysis, adjusted by standard cardiovascular risk factors, was utilized to determine associations of lipoproteins with coronary heart disease. RESULTS: Those with new-onset coronary heart disease were older, diabetic, smokers, had less education, used more lipid-lowering medication, and had a more atherogenic lipoprotein profile. After adjustment, the apo A1 remnant ratio (hazard ratio = 0.67 per 1-SD, p = 0.002) was strongly associated with coronary heart disease incidence. This association appears to be driven by the IDL-C denominator (hazard ratio = 1.23 per 1-SD, p = 0.007). Remnants (hazard ratio = 1.21 per 1-SD, p = 0.017), but not apo A1 (hazard ratio = 0.85 per 1-SD, p = 0.121) or VLDL3-C (hazard ratio = 1.13 per 1-SD, p = 0.120) were associated with coronary heart disease. Standard lipids were not associated with coronary heart disease incidence. CONCLUSION: We found the apo A1 remnant ratio to be strongly associated with coronary heart disease. This ratio appears to better stratify risk than standard lipids, apo A1, and remnants among a primary prevention cohort of African Americans. Its utility requires further study as a lipoprotein management target for risk reduction.

Association of high-density lipoprotein subclasses and incident coronary heart disease: The Jackson Heart and Framingham Offspring Cohort Studies.

AIMS: We aimed to clarify the associations of high-density lipoprotein cholesterol (HDL-C) subclasses with incident coronary heart disease (CHD) in two large primary prevention cohorts. METHODS: We measured cholesterol at baseline from the two major HDL subfractions (larger, more buoyant HDL2 and smaller, denser HDL3) separated by density gradient ultracentrifugation in 4114 (mean age 53.8 years; 64% female) African American participants from the Jackson Heart Study and 818 (mean age 57.3 years, 52% female) predominantly Caucasian participants from the Framingham Offspring Cohort Study. Multivariable adjusted hazard ratios (HRs) for HDL-C and its subclasses were derived from Cox proportional hazards regression models to estimate associations with incident CHD events including myocardial infarction, CHD death, and revascularization. Analyses were performed for each cohort separately and as a combined population. RESULTS: In models adjusted for cardiovascular risk factors for the combined population, HDL3-C (HR 0.76 per SD increase; 95% confidence interval (CI), 0.62-0.94; p = 0.01), rather than HDL2-C (HR 0.88 per SD; 95% CI, 0.72-1.09; p = 0.24) drove the inverse association of HDL-C (HR 0.79 per SD; 95% CI, 0.64-0.98; p = 0.03) with CHD. Similar associations were seen in multivariable analyses within each cohort including after adjusting for apolipoprotein A1 in the Jackson Heart Study. CONCLUSION: Smaller, denser HDL3-C levels are primarily responsible for the inverse association between HDL-C and incident CHD in this diverse group of primary prevention subjects. These findings have important implications ranging from considerations of HDL biology to interpretations of clinical trials utilizing HDL-C therapeutics.

Remnant Lipoprotein Cholesterol and Mortality After Acute Myocardial Infarction: Further Evidence for a Hypercholesterolemia Paradox From the TRIUMPH Registry.

BACKGROUND: Remnants are partially hydrolyzed, triglyceride-rich lipoproteins that, like other apolipoprotein B-containing lipoproteins, are atherogenic. Prior observational studies suggest paradoxically better outcomes in hypercholesterolemic patients who sustain an acute myocardial infarction (AMI), one of several known recurrent risk paradoxes. To date, the association of directly measured remnant lipoprotein cholesterol (RLP-C) with survival after an AMI has not been examined. HYPOTHESIS: Higher RLP-C levels may be paradoxically associated with lower mortality. METHODS: We examined 2465 AMI survivors in a prospective, 24-center US study of AMI outcomes. Lipoprotein cholesterol subfractions were directly measured by ultracentrifugation. RLP-C was defined as intermediate-density lipoprotein cholesterol (IDL-C) + very-low-density lipoprotein cholesterol subfraction 3 (VLDL3 -C). Given a linear relationship between RLP-C and mortality, we examined RLP-C by tertiles and continuously. Cox regression hazard ratios (HRs) were adjusted for the Global Registry of Acute Coronary Events (GRACE) score and 23 other covariates. RESULTS: Participants were age 58 ± 12 years (mean ± SD), and 68% were men. After 2 years of follow-up, 226 (9%) participants died. The mortality proportion was 12.4% in the lowest tertile of RLP-C (0-15 mg/dL), 8.5% in the middle tertile (16-23 mg/dL), and 6.8% in the highest tertile (24-120 mg/dL; P < 0.001). A 1-SD increase in RLP-C (11 mg/dL) predicted a 24% lower adjusted risk of 2-year mortality (HR: 0.76, 95% confidence interval [CI]: 0.64-0.91). Similar results were found for a 1-SD increase in IDL-C (HR per 8 mg/dL: 0.80, 95% CI: 0.67-0.96), VLDL3 -C (HR per 4 mg/dL: 0.74, 95% CI: 0.61-0.89), and very-low-density lipoprotein cholesterol (VLDL-C; HR per 8 mg/dL: 0.69, 95% CI: 0.55-0.85). CONCLUSIONS: Higher RLP-C levels were associated with lower mortality 2 years after AMI despite rigorous adjustment for known confounders. Unknown protective factors or a lead-time bias likely explains the paradox.

Relationship of the triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio to the remainder of the lipid profile: The Very Large Database of Lipids-4 (VLDL-4) study.

BACKGROUND: High levels of the triglycerides to high-density lipoprotein cholesterol (TG/HDL-C) ratio are associated with obesity, metabolic syndrome, and insulin resistance. OBJECTIVES: We evaluated variability in the remaining lipid profile, especially remnant lipoprotein particle cholesterol (RLP-C) and its components (very low-density lipoprotein cholesterol subfraction 3 and intermediate-density lipoprotein cholesterol), with variability in the TG/HDL-C ratio in a very large study cohort representative of the general U.S. METHODS: We examined data from 1,350,908 US individuals who were clinically referred for lipoprotein cholesterol ultracentrifugation (Atherotech, Birmingham, AL) from 2009 to 2011. Demographic information other than age and sex was not available. Changes to the remaining lipid profile across percentiles of the TG/HDL-C ratio were quantified, as well as by three TG/HDL-C cut-off points previously proposed in the literature: 2.5 (male) and 2 (female), 3.75 (male) and 3 (female), and 3.5 (male and female). RESULTS: The mean age of our study population was 58.7 years, and 48% were men. The median TG/HDL-C ratio was 2.2. Across increasing TG/HDL-C ratios, we found steadily increasing levels of RLP-C, non-HDL-C and LDL density. Among the lipid parameters studied, RLP-C and LDL density had the highest relative increase when comparing individuals with elevated TG/HDL-C levels to those with lower TG/HDL-C levels using established cut-off points. Approximately 47% of TG/HDL-C ratio variance was attributable to RLP-C. CONCLUSIONS: In the present analysis, a higher TG/HDL-C ratio was associated with an increasingly atherogenic lipid phenotype, characterized by higher RLP-C along with higher non-HDL-C and LDL density.

Patient-Level Discordance in Population Percentiles of the Total Cholesterol to High-Density Lipoprotein Cholesterol Ratio in Comparison With Low-Density Lipoprotein Cholesterol and Non-High-Density Lipoprotein Cholesterol: The Very Large Database of Lipids Study (VLDL-2B).

BACKGROUND: The total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C) ratio, estimated low-density lipoprotein cholesterol (LDL-C), and non-HDL-C are routinely available from the standard lipid profile. We aimed to assess the extent of patient-level discordance of TC/HDL-C with LDL-C and non-HDL-C, because discordance suggests the possibility of additional information. METHODS AND RESULTS: We compared population percentiles of TC/HDL-C, Friedewald-estimated LDL-C, and non-HDL-C in 1 310 432 US adults from the Very Large Database of Lipids. Lipid testing was performed by ultracentrifugation (Vertical Auto Profile, Atherotech, AL). One in 3 patients had ≥25 percentile units discordance between TC/HDL-C and LDL-C, whereas 1 in 4 had ≥25 percentile units discordance between TC/HDL-C and non-HDL-C. The proportion of patients with TC/HDL-C > LDL-C by ≥25 percentile units increased from 3% at triglycerides <100 mg/dL to 51% at triglycerides 200 to 399 mg/dL. On a smaller scale, TC/HDL-C > non-HDL-C discordance by ≥25 percentile units increased from 6% to 21%. In those with <15th percentile levels of LDL-C (<70 mg/dL) or non-HDL-C (<93 mg/dL), a respective 58% and 46% were above the percentile-equivalent TC/HDL-C of 2.6. Age, sex, and directly measured components of the standard lipid profile explained >86% of the variance in percentile discordance between TC/HDL-C versus LDL-C and non-HDL-C. CONCLUSIONS: In this contemporary, cross-sectional, big data analysis of US adults who underwent advanced lipid testing, the extent of patient-level discordance suggests that TC/HDL-C may offer potential additional information to LDL-C and non-HDL-C. Future studies are required to determine the clinical implications of this observation. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01698489.

HDL cholesterol subclasses, myocardial infarction, and mortality in secondary prevention: the Lipoprotein Investigators Collaborative.

AIMS: High-density lipoprotein (HDL) is highly heterogeneous and the link of its subclasses to prognosis remains controversial. We aimed to rigorously examine the associations of HDL subclasses with prognosis in secondary prevention. METHODS AND RESULTS: We collaboratively analysed data from two, complementary prospective cohorts: the TRIUMPH study of 2465 acute myocardial infarction patients, and the IHCS study of 2414 patients who underwent coronary angiography. All patients had baseline HDL subclassification by vertical-spin density gradient ultracentrifugation. Given non-linearity, we stratified by tertiles of HDL-C and its two major subclasses (HDL2-C, HDL3-C), then compared multivariable-adjusted hazard ratios for mortality and mortality/myocardial infarction. Patients were middle-aged to elderly (TRIUMPH: 58.2 ± 12.2 years; IHCS: 62.6 ± 12.6 years), and the majority were men (TRIUMPH: 68.0%; IHCS: 65.5%). IHCS had lower mean HDL-C levels (34.6 ± 10.1 mg/dL) compared with TRIUMPH (40 ± 10.6 mg/dL). HDL3-C accounted for >3/4 of HDL-C (mean HDL3-C/HDL-C 0.78 ± 0.05 in both cohorts). During 2 years of follow-up in TRIUMPH, 226 (9.2%) deaths occurred, while death/myocardial infarction occurred in 401 (16.6%) IHCS patients over 5 years. No independent associations with outcomes were observed for HDL-C or HDL2-C. In contrast, the lowest tertile of HDL3-C was independently associated with >50% higher risk in each cohort (TRIUMPH: with middle tertile as reference, fully adjusted HR for mortality of HDL3-C, 1.57; 95% CI, 1.13-2.18; IHCS: fully adjusted HR for mortality/myocardial infarction, 1.55; 95% CI, 1.20-2.00). CONCLUSION: In secondary prevention, increased risk for long-term hard clinical events is associated with low HDL3-C, but not HDL2-C or HDL-C, highlighting the potential value of subclassifying HDL-C.

Very large database of lipids: rationale and design.

Blood lipids have major cardiovascular and public health implications. Lipid-lowering drugs are prescribed based in part on categorization of patients into normal or abnormal lipid metabolism, yet relatively little emphasis has been placed on: (1) the accuracy of current lipid measures used in clinical practice, (2) the reliability of current categorizations of dyslipidemia states, and (3) the relationship of advanced lipid characterization to other cardiovascular disease biomarkers. To these ends, we developed the Very Large Database of Lipids (NCT01698489), an ongoing database protocol that harnesses deidentified data from the daily operations of a commercial lipid laboratory. The database includes individuals who were referred for clinical purposes for a Vertical Auto Profile (Atherotech Inc., Birmingham, AL), which directly measures cholesterol concentrations of low-density lipoprotein, very low-density lipoprotein, intermediate-density lipoprotein, high-density lipoprotein, their subclasses, and lipoprotein(a). Individual Very Large Database of Lipids studies, ranging from studies of measurement accuracy, to dyslipidemia categorization, to biomarker associations, to characterization of rare lipid disorders, are investigator-initiated and utilize peer-reviewed statistical analysis plans to address a priori hypotheses/aims. In the first database harvest (Very Large Database of Lipids 1.0) from 2009 to 2011, there were 1 340 614 adult and 10 294 pediatric patients; the adult sample had a median age of 59 years (interquartile range, 49-70 years) with even representation by sex. Lipid distributions closely matched those from the population-representative National Health and Nutrition Examination Survey. The second harvest of the database (Very Large Database of Lipids 2.0) is underway. Overall, the Very Large Database of Lipids database provides an opportunity for collaboration and new knowledge generation through careful examination of granular lipid data on a large scale.