Krishnaji R. Kulkarni

Increased Prevalence of Smaller and Denser LDL Particles in Asian Indians

There is increasing evidence to believe that Asian Indians are at an increased risk of coronary heart disease (CHD), which cannot be attributed to the common risk factors. Individuals with small, dense LDL phenotype are also known to be at increased risk of CHD. Our objective was to examine whether the prevalence of smaller and denser LDL particles is increased in Asian Indians. Thirty-nine Asian Indians (22 men and 17 women), aged 25 to 45 years, were matched with 39 whites for age and gender. Cholesterol profiles of lipoprotein classes and LDL subclasses were measured using the Vertical Auto Profile-II (VAP-II) and LDL-VAP-II methods, respectively. Six LDL subclasses (LDL1 to LDL6) have been identified using the LDL-VAP-II, with LDL1 and LDL6, respectively, being the most and least buoyant subclasses. The prevalence of small, dense LDL type (subjects with major LDL subclass 5 or 6) was significantly higher in Asian Indians compared with white subjects (44% versus 21%; P<0.05). The relative position of the major LDL density peak (LDL-Rf) on 0 to 1 scale in LDL-VAP-II density gradient was also significantly decreased in Asian Indians (0.462+/-0.076 versus 0. 505+/-0.086; P<0.02), suggesting an increased LDL density. Furthermore, this increased prevalence of small, dense LDL type appears to be due to the increased triglycerides (TG) (r for LDL-Rf versus TG=0.681, P<0.001), with fasting insulin being one of the important determinants of TG (r for TG versus fasting insulin=0.572, P<0.001). In addition, fasting insulin was significantly increased in Asian Indians with small, dense LDL type compared with other Asian Indians, suggesting a significant role of insulin resistance in increasing the prevalence of small, dense LDL type. We conclude that the increased prevalence of small, dense LDL observed in Asian Indians might contribute to their increased CHD risk.

Multiple Lipoprotein Abnormalities Associated with Insulin Resistance in Healthy Volunteers Are Identified by the Vertical Auto Profile-II Methodology

The lipoprotein abnormalities first associated with insulin resistance (IR) and compensatory hyperinsulinemia were high plasma triglyceride (TG) and low HDL-cholesterol (HDL-C) concentrations (1)(2). It is now known that the characteristic IR-associated dyslipidemia also includes a shift to smaller, denser LDL particles (pattern B), enhanced postprandial lipemia, and decreased concentration of the more buoyant HDL particle, HDL2 (3)(4)(5). Recently, the IR-associated lipoprotein abnormalities that increase risk of coronary heart disease (CHD) have continued to expand. In addition to high plasma TG and low HDL-C concentrations (6)(7), at least three classes of TG-rich lipoproteins are both atherogenic and associated with increased CHD risk, including intermediate density lipoprotein (IDL; a TG-rich remnant product derived from VLDL metabolism) (8)(9), VLDL3 (the dense VLDL subclass) (10)(11), and TG-rich chylomicron remnants (8)(12)(13). Despite awareness of the myriad IR-associated proatherogenic lipoprotein abnormalities (1)(2)(3)(4)(5)(14)(15)(16)(17), we are unaware of previous publications in which both IR and all relevant lipoproteins were quantified in the same cohort of individuals. This is likely partly attributable to the unavailability of analytical methods to measure multiple lipoprotein CHD risk factors in a clinically useful manner. However, the validated vertical auto profile-II (VAP-II) methodology (18) provides a means to comprehensively identify the IR-associated dyslipidemic profile, and we have used VAP-II to compare lipoprotein characteristics of nondiabetic individuals stratified into IR and insulin-sensitive (IS) groups. The Stanford University Human Subjects Committee approved this study, and healthy volunteers from the San Francisco Bay Area gave informed consent. Participants underwent medical interview, anthropometric measurements, and a physical examination. Exclusion criteria included fasting plasma glucose >7.0 mmol/L (126 mg/dL), total bilirubin >34 μmol/L (2.0 …

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

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 U.S. adults from the Very Large Database of Lipids. Lipid testing was performed by ultracentrifugation (VAP, Atherotech, AL). One in three patients had ≥25 percentile units discordance between TC/HDL-C and LDL-C while one in four 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 non-HDL-C discordance by ≥25 percentile units increased from 6% to 21%. In those with 86% of the variance in percentile discordance between TC/HDL-C vs. LDL-C and non-HDL-C. Conclusions —In this contemporary, cross-sectional, big data analysis of U.S. 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 Information —www.clinicaltrials.gov. Identifier: [NCT01698489][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01698489&atom=%2Fcirculationaha%2Fearly%2F2015%2F07%2F02%2FCIRCULATIONAHA.115.016163.atomBackground— 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.

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 U.S. adults from the Very Large Database of Lipids. Lipid testing was performed by ultracentrifugation (VAP, Atherotech, AL). One in three patients had ≥25 percentile units discordance between TC/HDL-C and LDL-C while one in four 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 non-HDL-C discordance by ≥25 percentile units increased from 6% to 21%. In those with 86% of the variance in percentile discordance between TC/HDL-C vs. LDL-C and non-HDL-C. Conclusions —In this contemporary, cross-sectional, big data analysis of U.S. 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 Information —www.clinicaltrials.gov. Identifier: [NCT01698489][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01698489&atom=%2Fcirculationaha%2Fearly%2F2015%2F07%2F02%2FCIRCULATIONAHA.115.016163.atomBackground— 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.

A new ratio for better predicting future death/myocardial infarction than standard lipid measurements in women >50 years undergoing coronary angiography: the apolipoprotein A1 remnant ratio (Apo A1/ [VLDL3+IDL])

BackgroundWomen often lag behind men in their risk of cardiovascular events. However, with age and the onset of menopause, women’s cardiovascular risk eventually becomes similar to that of men. This change in risk may, in part, be attributable to a shift to a more atherogenic lipid profile. Our objective was to evaluate standard- and sub-lipid parameters and the apo A1 remnant ratio: (apo A1/[VLDL3-C+IDL-C]) for their associations with death/myocardial infarction among peri- and post-menopausal women.MethodsWomen (N=711) >50 years of age undergoing coronary angiography were evaluated. Baseline clinical and angiographic characteristics, lipids, and sub-lipid levels (Vertical Auto Profile method) were collected. Cox regression analysis, adjusted by standard cardiovascular risk factors, was utilized to determine associations of lipid and sub-lipid tertiles(T) with death/myocardial infarction at 1 and 3 years.ResultsPatients averaged 67.7±9.4 years and 53.6% had underlying severe (≥70% stenosis) coronary artery disease. The apo A1 remnant ratio was found to have stronger associations for 1 year (T1 vs. T3: HR=2.13, p=0.03, T2 vs. T3: HR=1.57, p=0.21) and 3 year (T1 vs. T3: HR=2.32, p=0.002, T2 vs. T3: HR=1.97, p=0.01) death/myocardial infarction than any individual lipid (LDL-C, HDL-C, triglycerides, non-HDL-C) or sub-lipid (apo A1, apo B, VLDL3-C+IDL-C) measure, or any other well-known ratio (triglyercies/HDL-C, apo B/A1, TChol/HDL-C, HDL-C/[VLDL3-C+IDL-C]).ConclusionsThe apo A1 remnant ratio was a significant predictor of short and intermediate-term death/myocardial infarction risk among women >50 years of age. Furthermore, this ratio was found to have greater predictive ability than traditional lipid and sub-lipid parameters and represents a potential new risk marker.

Relative Effects of Insulin Resistance and Protease Inhibitor Treatment on Lipid and Lipoprotein Metabolism in HIV-Infected Patients

Abstract Background: The relationship between insulin resistance, dyslipidemia, HIV infection, and antiretroviral therapy remains unclear, and the atherogenic nature of lipid and lipoprotein profiles in HIV-infected patients has not been fully characterized. Method: We measured plasma lipid and lipoprotein subfractions using Vertical Auto Profile-II methodology and directly measured insulin-mediated glucose disposal in 45 protease inhibitor (PI)-treated and non-PI-treated HIV-infected patients. Results: PI-treated patients had higher total, LDL, and narrow-density LDL cholesterol (p < .05) and a trend toward higher triglycerides, whereas HDL cholesterol and LDL particle characteristics were unrelated to PI use or history of lipodystrophy. Insulin sensitivity did not differ on the basis of PI therapy, but decreased insulin sensitivity was associated with lower HDL and HDL-3 cholesterol (p < .01); elevated triglyceride (p < .01), VLDL 1+2, and VLDL 3a+3b lipoproteins (p < .01); and smaller, denser (more atherogenic) LDL particle characteristics (p < .01). Thus, the lipoprotein abnormality associated with PI use was increased LDL cholesterol, whereas changes in TG and HDL metabolism were associated with insulin resistance, independent of PI use. Conclusion: The variables of PI-treatment, dyslipidemia, lipodsytrophy, and insulin resistance do not always cluster together in HIV-infected patients, which suggests that the metabolic phenotype emerging in treated patients results from a complex interplay of drug effects, immune restoration, and baseline insulin sensitivity.

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. Design: Cross-sectional adjusted associations for lipids, lipoprotein subclasses, lipoprotein insulin resistance score, inflammatory, coagulation, and glycemic biomarkers by analysis of covariance for thyroid categories or thyroid stimulating hormone (TSH) quintiles on a Women’s Health Study subcohort. Setting: Outpatient. Patients or Other Participants: Randomly sampled 3914 middle-aged and older women for thyroid function analysis (TSH, free T4), of whom 3321 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 subclass profiles were indicative of insulin resistance (respective values and P for trend): larger very-low-density lipoprotein size (nm) (51.5 [95% confidence interval (CI), 51.2, 51.8] to 52.9 [51.8, 54.1], P = 0.001); higher low-density lipoprotein (LDL) particle concentration (nmol/L) [1283 (95% CI, 1267, 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 of 0.008. Of the other biomarkers, SCH and HT were associated with higher high-sensitivity C-reactive protein and hemoglobin A1c. For increasing TSH quintiles, results were overall similar. Conclusions: In apparently healthy women, SCH cardiometabolic profiles indicated worsening insulin resistance and higher cardiovascular disease risk markers compared with euthyroid individuals, despite similar LDL and total cholesterol. These findings suggest that cardiometabolic risk may increase early in the progression toward SCH and overt HT.

Greater remnant lipoprotein cholesterol reduction with pitavastatin compared to pravastatin in HIV-infected patients: The INTREPID trial

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.

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.

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.