Are Remnant-Like Particles Independent Predictors of Coronary Heart Disease Incidence?

Association between remnant cholesterol and the risk of cardiovascular disease in Chinese population

OBJECTIVES

Previous genetic, observational, and clinical intervention studies reported that circulating levels of remnant cholesterol was associated with cardiovascular disease (CVD). However, whether remnant cholesterol can predict CVD events in Chinese population was not well characterized.

STUDY DESIGN

This was a prospective cohort study.

METHODS

We used the data of 9456 Chinese adults aged ≥45 years from the China Health and Retirement Longitudinal Study (CHARLS). Estimated remnant cholesterol was calculated as total cholesterol minus high-density lipoprotein cholesterol minus low-density lipoprotein cholesterol. Cox proportional hazard models and restricted cubic spline models were used to assess the relationships between remnant cholesterol levels and CVD, stroke and cardiac events.

RESULTS

During 7 years of follow-up, a total of 886 (9.37 %) respondents experienced CVD, 392 (4.15 %) experienced stroke and 544 (5.75 %) experienced cardiac events. In multivariable-adjusted analyses, the adjusted hazard ratios (95 % confidence interval) for the highest versus lowest quartile of remnant cholesterol were 1.14 (1.02-1.32) for CVD and 1.43 (1.12-1.82) for stroke, and each 1-SD increase of log-transformed remnant cholesterol (2.93 mg/dl) was associated with 5 % and 11 % increased risk of the CVD and stroke, respectively. Remnant cholesterol was not associated with increased risk of cardiac events.

CONCLUSION

Elevated remnant cholesterol levels were positively associated with CVD and stroke in Chinese adult population, suggesting that remnant cholesterol could be considered as a preferential predictor and treatment target of CVD in Chinese population.

Research trends in lipid-lowering therapies for coronary heart disease combined with hyperlipidemia: a bibliometric study and visual analysis

Background

Cardiovascular disease (CVD) poses a significant global health and economic challenge, with atherosclerosis being a primary cause. Over the past 40 years, substantial research has been conducted into the prevention and reversal of atherosclerosis, resulting in the development of lipid-lowering agents such as statins and fibrates. Despite the extensive literature and formulation of numerous therapeutic guidelines in this domain, a comprehensive bibliometric analysis of the current research landscape and trends has not been performed. This study aimed to elucidate the evolution and milestones of research into lipid-lowering treatments for coronary heart disease (CHD) in conjunction with hyperlipidemia through bibliometric analysis, offering insights into future directions for treatment strategies.

Methods

This study examined publications from 1986 to 2023 retrieved from the Web of Science database (Core Collection). Utilizing tools such as VOSviewer, Pajek, and CiteSpace, we analyzed publication and citation numbers, H-indexes, contributions by countries and institutions, authorship, journal sources, and keyword usage to uncover research trajectories and areas of focus.

Results

Our analysis of 587 publications revealed a recent surge in research output, particularly post-2003. The American Journal of Cardiology published the highest number of studies, with 40 articles, whereas Circulation received the highest number of citations (6,266). Key contributors included the United States, Japan, and China, with the United States leading in citation numbers and the H-index. Harvard University and Leiden University emerged as pivotal institutions, and Professors J. Wouter Jukema and Robert P. Giugliano were identified as leading experts. Keyword analysis disclosed five thematic clusters, indicating a shift in research towards new drug combinations and strategies, signaling future research directions.

Conclusion

The last 4 decades have seen a notable rise in publications on lipid-lowering therapies for CHD and hyperlipidemia, with the United States retaining world-leading status. The increase in international collaboration aids the shift towards research into innovative lipid-lowering agents and therapeutic approaches. PCSK9 inhibitors and innovative combination therapies, including antisense oligonucleotides and angiopoietin-like protein 3 inhibitors, provide avenues for future research, intending to maximize the safety and efficacy of treatment approaches.

The Role of Triglyceride-rich Lipoproteins and Their Remnants in Atherosclerotic Cardiovascular Disease

Atherosclerotic cardiovascular disease (ASCVD) is the world's leading cause of death. ASCVD has multiple mediators that therapeutic interventions target, such as dyslipidaemia, hypertension, diabetes and heightened systemic inflammatory tone, among others. LDL cholesterol is one of the most well-studied and established mediators targeted for primary and secondary prevention of ASCVD. However, despite the strength of evidence supporting LDL cholesterol reduction by multiple management strategies, ASCVD events can still recur, even in patients whose LDL cholesterol has been very aggressively reduced. Hypertriglyceridaemia and elevated levels of triglyceride-rich lipoproteins (TRLs) may be key contributors to ASCVD residual risk. Several observational and genetic epidemiological studies have highlighted the causal role of triglycerides within the TRLs and/or their remnant cholesterol in the development and progression of ASCVD. TRLs consist of intestinally derived chylomicrons and hepatically synthesised very LDL. Lifestyle modification has been considered the first line intervention for managing hypertriglyceridaemia. Multiple novel targeted therapies are in development, and have shown efficacy in the preclinical and clinical phases of study in managing hypertriglyceridaemia and elevated TRLs. This comprehensive review provides an overview of the biology, pathogenicity, epidemiology, and genetics of triglycerides and TRLs, and how they impact the risk for ASCVD. In addition, we provide a summary of currently available and novel emerging triglyceride-lowering therapies in development.

Fibrates, Hypertriglyceridemia, and CVD Risk: Where Do We Stand After the PROMINENT Trial for Triglyceride Lowering?

PURPOSE OF REVIEW

To evaluate recent clinical trials focusing on patients with hypertriglyceridemia.

RECENT FINDINGS

Randomized clinical trials have recently been undertaken in hypertriglyceridemic patients to determine whether effective reductions in triglycerides would improve cardiovascular disease (CVD) outcomes. However, the fibric acid derivative, pemafibrate, failed to reduce cardiovascular events despite significant reductions (~ 25-35%) in triglyceride levels and despite background statin therapy. In contrast, icosapent ethyl, a highly purified omega-3 fatty acid was previously shown to reduce CVD events in hypertriglyceridemic patients, despite more modest reductions (~ 20%) in triglyceride levels in statin treated patients. The divergent results obtained in patients with hypertriglyceridemia (HTG), a group at particularly high risk of CVD, especially when coupled with other risk factors, indicates that triglyceride lowering in of itself is insufficient to offset CVD risk. Rather, the effectiveness of therapy in this high-risk cohort may be the result of the suppression of the inherent atherogenic properties associated with HTG.

Cholesterol Remnants, Triglyceride-Rich Lipoproteins and Cardiovascular Risk

Randomized clinical trials with statins and other lipid-lowering drugs have shown the presence of a "residual cardiovascular risk" in those treated to "target" for LDL-cholesterol. This risk is mainly associated to lipid components other than LDL and in particular to remnant cholesterol (RC) and to lipoproteins rich in triglycerides in fasting and non-fasting conditions. During fasting, RCs correspond to the cholesterol content of the VLDL and their partially depleted triglyceride remnant containing apoB-100. Conversely, in non-fasting conditions, RCs include also cholesterol present in chylomicrons containing apoB-48. Therefore, RCs refer to total plasma cholesterol minus HDL-cholesterol and LDL-cholesterol, that is, all the cholesterol present in the VLDL, chylomicrons and in their remnants. A large body of experimental and clinical data suggests a major role of RCs in the development of atherosclerosis. In fact, RCs easily pass the arterial wall and bind to the connective matrix stimulating the progression of smooth muscle cells and the proliferation of resident macrophages. RCs are a causal risk factor for cardiovascular events. Fasting and non-fasting RCs are equivalent for predicting vascular events. Further studies on drugs effect on RC levels and clinical trials to evaluate the efficacy of RC reduction on cardiovascular events are needed.

Prognostic value of remnant cholesterol in patients with coronary heart disease: A systematic review and meta-analysis of cohort studies

Background

The relationship between abnormal lipid levels and atherosclerotic cardiovascular diseases is well established, but the association between remnant cholesterol (RC) and coronary heart disease (CHD) remains uncertain. The aim of this meta-analysis is to systematically evaluate the prognostic value of RC concentration in patients with CHD.

Methods

PubMed, EMBASE, Cochrane, and Web of Science databases were reviewed to identify relevant observational cohort studies published in English up to December 2021. Random-effects meta-analysis compared the highest and lowest RC concentration. The primary outcome was a composite of major adverse cardiovascular events (MACEs) and all-cause mortality in patients with CHD.

Results

A total of 10 studies recruiting 30,605 patients with CHD were selected to be included in this meta-analysis. Patients with CHD with elevated RC concentration had an increased risk of the composite endpoint events (RR = 1.54, 95% CI: 1.26-1.87) and MACEs (RR = 1.70, 95% CI: 1.54-1.88), but the risk of all-cause mortality was not statistically significant (RR = 1.16, 95% CI: 0.79-1.69, P = 0.44). Subgroup analysis showed consistent results.

Conclusion

Our results suggest that elevated concentration RC may independently predict MACEs in patients with CHD. Determination of RC concentration may improve risk stratification of prognosis in patients with CHD. However, more high-quality studies are necessary to confirm this association.

A Multi-Center, Prospective Observational Study to Investigate the Safety, Compliance, and Efficacy of Omethyl QTlet Soft Capsule

Omega-3 fatty acids have been shown to be effective in lowering triglyceride (TG) levels; however, tolerability issues arise due to the large size of the pills. The purpose of this study was to examine the safety, compliance, and efficacy of Omethyl QTlet soft capsules (OQCs). This multi-center, prospective, observational study evaluated the safety, compliance, and efficacy of OQCs. Patients with hypertriglyceridemia with a history of omega-3 fatty acid intake were enrolled in this study and were prescribed OQCs (2 g−4 g/day) for eight weeks. All adverse events (AEs), adverse drug reactions (ADRs), and serious adverse events (SAEs) were recorded for safety evaluation. Adherence to treatment was assessed using questionnaires, and efficacy was assessed by changes in lipid and lipoprotein levels after eight weeks from baseline. The convenience of taking medication was analyzed for 580 patients, and the efficacy test was performed for 563 patients. The AE and ADR rates were 8.2% and 5.7%, respectively. There were only two SAEs. Of the patients, 55.8% responded that the OQC improved medication convenience, and mean changes in TG, total cholesterol, LDL-C, and non-HDL-C from baseline to eight weeks were −37.88 mg/dL, −11.56 mg/dL, −5.55 mg/dL, and −10.87 mg/dL, respectively (p-values < 0.001). In patients who had previously taken omega-3 fatty acids, OQCs showed safety and efficacy in lowering TG, and it was confirmed that compliance with medicine also improved compared to omega-3 fatty acids.

New insight into dyslipidemia‐induced cellular senescence in atherosclerosis

Atherosclerosis, characterized by lipid‐rich plaques in the arterial wall, is an age‐related disorder and a leading cause of mortality worldwide. However, the specific mechanisms remain complex. Recently, emerging evidence has demonstrated that senescence of various types of cells, such as endothelial cells (ECs), vascular smooth muscle cells (VSMCs), macrophages, endothelial progenitor cells (EPCs), and adipose‐derived mesenchymal stem cells (AMSCs) contributes to atherosclerosis. Cellular senescence and atherosclerosis share various causative stimuli, in which dyslipidemia has attracted much attention. Dyslipidemia, mainly referred to elevated plasma levels of atherogenic lipids or lipoproteins, or functional impairment of anti‐atherogenic lipids or lipoproteins, plays a pivotal role both in cellular senescence and atherosclerosis. In this review, we summarize the current evidence for dyslipidemia‐induced cellular senescence during atherosclerosis, with a focus on low‐density lipoprotein (LDL) and its modifications, hydrolysate of triglyceride‐rich lipoproteins (TRLs), and high‐density lipoprotein (HDL), respectively. Furthermore, we describe the underlying mechanisms linking dyslipidemia‐induced cellular senescence and atherosclerosis. Finally, we discuss the senescence‐related therapeutic strategies for atherosclerosis, with special attention given to the anti‐atherosclerotic effects of promising geroprotectors as well as anti‐senescence effects of current lipid‐lowering drugs.

A Fishy Topic: VITAL, REDUCE-IT, STRENGTH, and Beyond: Putting Omega-3 Fatty Acids into Practice in 2021

PURPOSE OF REVIEW

To examine recently published data from clinical outcome and arteriographic studies that examined the addition of omega-3 fatty acids, eicosapentaenoic acid (EPA) + docosahexanoic acid (DHA), to standard of care therapy on cardiovascular disease (CVD) risk.

RECENT FINDINGS

Several trials that tested purified EPA (JELIS, REDUCE-IT, EVAPORATE) were associated with reduced CVD risk and regression of low attenuation coronary plaque volume, whereas studies that employed the combination EPA/DHA (VITAL, OMEMI, STRENGTH) failed to derive clinical benefit. Trials testing purified EPA consistently demonstrated reduction in atheromatous volume or CVD events beyond standard of care therapies, whereas the combination of EPA/DHA did not, despite producing similar reductions in triglycerides. Experimental and in vitro data suggest that compared to DHA, EPA exhibits antioxidant, anti-inflammatory, and membrane stabilizing properties that enhance vascular function and CVD risk. Consequently, purified EPA appears to be the treatment of choice for high-risk patients with hypertriglyceridemia.

Triglyceride-Rich Lipoprotein Remnants and Cardiovascular Disease

BACKGROUND

Triglycerides, cholesterol, and their metabolism are linked due to shared packaging and transport within circulating lipoprotein particles. While a case for a causal role of cholesterol-carrying low-density lipoproteins (LDLs) in atherosclerosis is well made, the body of scientific evidence for a causal role of triglyceride-rich lipoproteins (TRLs) is rapidly growing, with multiple lines of evidence (old and new) providing robust support.

CONTENT

This review will discuss current perspectives and accumulated evidence that an overabundance of remnant lipoproteins stemming from intravascular remodeling of nascent TRLs-chylomicrons and very low-density lipoproteins (VLDL)-results in a proatherogenic milieu that augments cardiovascular risk. Basic mechanisms of TRL metabolism and clearance will be summarized, assay methods reviewed, and pivotal clinical studies highlighted.

SUMMARY

Remnant lipoproteins are rendered highly atherogenic by their high cholesterol content, altered apolipoprotein composition, and physicochemical properties. The aggregate findings from multiple lines of evidence suggest that TRL remnants play a central role in residual cardiovascular risk.

Evaluation of atherogenic lipoprotein-cholesterol to HDL cholesterol ratio as a prognostic test for ST-segment elevation myocardial infarction

Background: The detectable component of triglyceride-rich lipoproteins (TGRLs), remnant lipoprotein cholesterol (RLP-c), has been proven being correlated with the progression of atherosclerosis and myocardial infarction. However, when taken as a risk predictor, the prognostic and diagnostic potential of RLP-c remains controversial in studies. In this study, we evaluated the hypothesis that atherogenic lipoprotein-cholesterol (AL-c), representing the sum of RLP-c and the sd-LDL-c, to the HDL-c ratio, could represent a better predictive indicator than RLP-c alone in ST-segment elevation myocardial infarction (STEMI). Methods: The 316 consecutive patients suffering from persistent chest discomfort admitted to the Shanghai General Hospital between January 2018 and June 2018 were enrolled. 149 STEMI patients (62% men, mean age 69.6 ± 13.3 years) were included as the study cohort. The AL-c/HDL-c ratio was calculated on admission in a cohort of electrocardiogram-confirmed STEMI patients and compared to other lipid profiles as a predictive indicator. Results: The AL-c/HDL-c ratio was significantly increased in STEMI patients compared with apparently healthy adults (0.93; IQR [0.71-1.18] vs 0.70; IQR [0.45-1.04]; p < 0.001). Gender dependency existed, and the male and female patients had median AL-c/HDL-c ratios of 1.01 and 0.79, respectively (p < 0.001). Compared to RLP-c, the AL-c/HDL-c ratio had a better prognostic value to predict STEMI risk in both sexes (AUC of 0.672 with a sensitivity of 0.794 in males and 0.613 with a sensitivity of 0.684 in females). Conclusions: The AL-c/HDL-c ratio could represent a convenient and sensitive biomarker for screening and predicting STEMI risk.

Prognostic utility of triglyceride-rich lipoprotein-related markers in patients with coronary artery disease

TG-rich lipoprotein (TRL)-related biomarkers, including TRL-cholesterol (TRL-C), remnant-like lipoprotein particle-cholesterol (RLP-C), and apoC-III have been associated with atherosclerosis. However, their prognostic values have not been fully determined, especially in patients with previous CAD. This study aimed to examine the associations of TRL-C, RLP-C, and apoC-III with incident cardiovascular events (CVEs) in the setting of secondary prevention of CAD. Plasma TRL-C, RLP-C, and total apoC-III were directly measured. A total of 4,355 participants with angiographically confirmed CAD were followed up for the occurrence of CVEs. During a median follow-up period of 5.1 years (interquartile range: 3.9-6.4 years), 543 (12.5%) events occurred. Patients with incident CVEs had significantly higher levels of TRL-C, RLP-C, and apoC-III than those without events. Multivariable Cox analysis indicated that a log unit increase in TRL-C, RLP-C, and apoC-III increased the risk of CVEs by 49% (95% CI: 1.16-1.93), 21% (95% CI: 1.09-1.35), and 40% (95% CI: 1.11-1.77), respectively. High TRL-C, RLP-C, and apoC-III were also independent predictors of CVEs in individuals with LDL-C levels ≤1.8 mmol/l (n = 1,068). The addition of RLP-C level to a prediction model resulted in a significant increase in discrimination, and all three TRL biomarkers improved risk reclassification. Thus, TRL-C, RLP-C, and apoC-III levels were independently associated with incident CVEs in Chinese CAD patients undergoing statin therapy.

Risk of cardiovascular events in patients with hypertriglyceridaemia: A review of real-world evidence

AIMS

To describe the real-world prevalence and consequences of hypertriglyceridaemia.

MATERIALS AND METHODS

We searched two large patient databases, the National Health and Nutrition Examination Survey (NHANES) database (2007-2014) and the Optum Research Database, as well as electronic medical records from two Kaiser Permanente regions.

RESULTS

The NHANES data showed that ~26% of US adults, including nearly one-third of statin users, had at least borderline hypertriglyceridaemia (triglycerides [TGs] ≥1.69 mmol/L), and ~40% of adults with diabetes had levels of ≥150 mg/dL despite statin use. The Optum analyses demonstrated that those with TG levels ≥1.69 mmol/L who were on statins had a significantly increased risk of composite initial major cardiovascular (CV) events (hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.19-1.34; P < 0.001 vs. patients with TGs <150 mg/dL). This was accompanied by increased healthcare utilization and direct healthcare costs (HR 1.12, 95% CI 1.08-1.16; P < 0.001). In the analyses of the Kaiser Permanente records, patients with diabetes and TG levels 2.26-5.64 mmol/L had significantly higher adjusted incidence rates of non-fatal myocardial infarction (rate ratio 1.30, 95% CI 1.08-1.58; P = 0.006), non-fatal stroke (rate ratio 1.23; 95% CI 1.01-1.49; P = 0.037) and coronary revascularization (rate ratio 1.21; 95% CI 1.02-1.43; P = 0.027), but not unstable angina (rate ratio 1.33; 95% CI 0.87-2.03; P = 0.185) compared with patients with TG levels <1.69 mmol/L.

CONCLUSIONS

Real-world analyses suggest that elevated TGs are prevalent and commonly associated with increased CV risk. CV outcomes trials in patients with established hypertriglyceridaemia will clarify whether strategies to reduce TG levels can ameliorate residual CV risk in patients taking statins.

Comparison of remnant cholesterol levels estimated by calculated and measured LDL-C levels in Chinese patients with coronary heart disease

BACKGROUND

Evidence about whether remnant cholesterol (RC), especially non-fasting RC, is a causal risk factor for coronary heart disease (CHD) in Chinese subjects is rare. Recently, estimated RC level (RCe) was applied in many studies with large population. We aimed to compare fasting and non-fasting RCe calculated by LDL-C level determined by different methods in Chinese subjects, and investigate their contributions to CHD.

METHODS

Levels of TC, TG and HDL-C were measured directly in 273 CHD patients (CHD group) and 136 controls (CON group) before and at 4 h after a daily breakfast. LDL-C level was measured directly or calculated by Friedewald equation at TG < 4.5 mmol/L. RC level estimated by calculated or measured LDL-C was termed as RCe1 or RCe2. Contributions of different RC levels to CHD were evaluated by multivariable logistic regression analysis.

RESULTS

Both RCe1 and RCe2 increased significantly at 4 h after breakfast (both p < 0.05). RCe1 was significantly higher than RCe2 in fasting or non-fasting state (p < 0.05). RCe1 was closely related to RCe2, especially in the highest quartile of RCe1 (p < 0.05). Non-fasting RCe1 or RCe2 and fasting RCe2 independently predicted CHD after adjustment for traditional risk factors (all p < 0.05).

CONCLUSIONS

Although RCe1 was significantly higher than RCe2, non-fasting RCe, no matter RCe1 or RCe2, after a daily breakfast was an independent predictor for CHD risk in Chinese subjects, indicating that the non-fasting state is critical in the development of atherosclerosis.

Association Between Occupational Exposure to Pesticides and Cardiovascular Disease Incidence: The Kuakini Honolulu Heart Program

Background

Previously, Kuakini Honolulu Heart Program researchers reported that occupational exposure to pesticides was significantly associated with total mortality. The current study examines occupational exposure to pesticides in relation to incident cardiovascular disease, defined as coronary heart disease or cerebrovascular accident.

Methods and Results

With the Occupational Safety Health Administration exposure scale used as an estimate of exposure, statistical analyses were performed on a cohort of 7557 Japanese‐American men from the Kuakini Honolulu Heart Program. Hazard ratios for cardiovascular disease incidence were calculated for various levels of pesticide exposure using Cox proportional hazards models. In the first 10 years of follow‐up, a positive association was observed between age‐adjusted cardiovascular disease incidence and high levels of pesticide exposure (hazard ratio=1.46, 95% CI=1.10‐1.95, P=0.009). This relationship remained significant after adjustment for other cardiovascular disease risk factors (hazard ratio=1.42, 95% CI=1.05‐1.92, P=0.021). No significant association for coronary heart disease or cerebrovascular accident incidence with pesticide exposure was observed when examined separately, possibly due to a smaller number of events.

Conclusions

These findings suggest that occupational exposure to pesticides may play a role in the development of cardiovascular diseases. The results are novel, as the association between occupational exposure to pesticides and cardiovascular disease incidence has not been examined previously in this unique cohort.

Remnant Lipoprotein Cholesterol and Cardiovascular and Cerebrovascular Events in Patients with Non-Alcoholic Fatty Liver Disease

: Non-alcoholic fatty liver disease (NAFLD) is characterized by an atherogenic dyslipidaemia and an increased cardiovascular risk. Remnant lipoprotein cholesterol (RLP-C) is emerging as a novel cardiovascular risk factor, but its predictive value in patients with NAFLD is unknown. We investigated factors affecting RLP-C levels, and the association with major adverse cardiovascular and cerebrovascular events (MACCE) in NAFLD. A prospective observational cohort study was carried out including 798 unselected patients with cardio-metabolic diseases screened by ultrasound for the presence of NAFLD. Fasting RLP-C (mg/dL) was calculated as total cholesterol-(HDL (high-density lipoprotein) + LDL (low-density-lipoprotein)). Primary endpoint of the follow-up study was a combined endpoint of MACCE. Patients with NAFLD (79.2%) had higher median fasting RLP-C in comparison to those without (27.0 vs. 20.0 mg/ dL, respectively p < 0.001). Metabolic syndrome, NAFLD, age above median, and female sex were independently associated to fasting RLP-C above the median. In patients with NAFLD, values of RLP-C were associated with liver disease severity, as shown by the increasing value of RLP-C across tertiles of aspartate aminotransferase (AST) (p = 0.002) and gamma-glutamyl transpeptidase (GGT) (p < 0.001). Furthermore, levels of RLP-C and Hamaguchi score, were significantly correlated (r = 0.193, p < 0.001). During a median follow-up of 32 months (interquartile range: 14.2⁻51.7, 1700 person-years), 41 MACCE (2.41%/year) were registered in 596 NAFLD patients. The rate of events was higher in NAFLD patients with RLP-C above the median compared to those below (log-rank test p = 0.040). Age (hazard ratio (HR) 1.039, 95% confidence interval (CI), 1.005⁻1.074, p = 0.024), previous cardiovascular events (HR 2.210, 95% CI, 1.052⁻4.643, p = 0.036), female sex (HR 0.454, 95% CI, 0.208⁻0.989, p = 0.047) and RLP-C above the median (HR 2.202, 95% CI, 1.132⁻4.285, p = 0.020) were associated with MACCE. In conclusion, we found that NAFLD was independently associated with higher circulating RLP-C, and that high RLP-C levels were predictive of MACCE in patients with NAFLD.

Lipid Profiles in Out-of-Hospital Sudden Unexpected Death

Objective

To determine the association between serum lipid measurements and the occurrence of out-of-hospital sudden unexpected death (OHSUD).

Patients and Methods

We compared 139 OHSUD cases (43 female patients [30.9%]) and 968 controls (539 female patients [55.7%]) from Wake County, North Carolina, from March 1, 2013, through February 28, 2015. Individuals were included if they were aged 18 to 64 years and had lipid measurements in the 5 years before their death (cases) or the most recent health care encounter (controls). Covariates were abstracted from medical records for all subjects, and those with triglyceride (TG) levels greater than 400 mg/dL (to convert to mmol/L, multiply by 0.0259) were excluded for low-density lipoprotein (LDL)–related analyses.

Results

By linear regression using age- and sex-adjusted models, cases of OHSUD had lower adjusted mean total cholesterol (170.3±52.2 mg/dL vs 188.9±39.7 mg/dL; P<.001), LDL cholesterol (90.9±39.6 mg/dL vs 109.6±35.2 mg/dL; P<.001), and non–high-density lipoprotein (HDL) (121.6±49.8 mg/dL vs 134.3±39.6 mg/dL; P<.001) levels and a higher adjusted TG/HDL-C ratio (4.7±7 vs 3±2.7; P<.001) than did controls. By logistic regression using age- and sex-adjusted models, the odds of OHSUD were elevated per unit increase in TG/HDL-C ratio (1.08; 95% CI, 1.03-1.12).

Conclusion

Out-of-hospital sudden unexpected death cases had more favorable levels of total cholesterol, LDL cholesterol, and non-HDL, possibly indicating a lack of association between traditional lipid cardiovascular risk factors and sudden unexpected death. A comparatively elevated TG/HDL-C ratio in cases may corroborate an evolving hypothesis of how vasoactive and prothrombotic remnant-like lipoprotein particles contribute to sudden unexpected death.

Triglycerides Revisited to the Serial

This review discusses the role of triglycerides (TGs) in the normal cardiovascular system as well as in the development and clinical manifestation of cardiovascular diseases. Regulation of TGs at the enzymatic and genetic level, in addition to their possible relevance as preclinical and clinical biomarkers, is discussed, culminating with a description of available and emerging treatments. Due to the high complexity of the subject and the vast amount of material in the literature, the objective of this review was not to exhaust the subject, but rather to compile the information to facilitate and improve the understanding of those interested in this topic. The main publications on the topic were sought out, especially those from the last 5 years. The data in the literature still give reason to believe that there is room for doubt regarding the use of TG as disease biomarkers; however, there is increasing evidence for the role of hypertriglyceridemia on the atherosclerotic inflammatory process, cardiovascular outcomes, and mortality.

Postprandial Hyperlipidemia and Remnant Lipoproteins

Fasting hypertriglyceridemia is positively associated with the morbidity of coronary heart disease (CHD), and postprandial (non-fasting) hypertriglyceridemia is also correlated with the risk status for CHD, which is related to the increase in chylomicron (CM) remnant lipoproteins produced from the intestine. CM remnant particles, as well as oxidized low density lipoprotein (LDL) or very low density lipoprotein (VLDL) remnants, are highly atherogenic and act by enhancing systemic inflammation, platelet activation, coagulation, thrombus formation, and macrophage foam cell formation. The cholesterol levels of remnant lipoproteins significantly correlate with small, dense LDL; impaired glucose tolerance (IGT) and CHD prevalence. We have developed an assay of apolipoprotein (apo)B-48 levels to evaluate the accumulation of CM remnants. Fasting apoB-48 levels correlate with the morbidity of postprandial hypertriglyceridemia, obesity, type III hyperlipoproteinemia, the metabolic syndrome, hypothyroidism, chronic kidney disease, and IGT. Fasting apoB-48 levels also correlate with carotid intima-media thickening and CHD prevalence, and a high apoB-48 level is a significant predictor of CHD risk, independent of the fasting TG level. Diet interventions, such as dietary fibers, polyphenols, medium-chain fatty acids, diacylglycerol, and long-chain n-3 polyunsaturated fatty acids (PUFA), ameliorate postprandial hypertriglyceridemia, moreover, drugs for dyslipidemia (n-3 PUFA, statins, fibrates or ezetimibe) and diabetes concerning incretins (dipeptidyl-peptidase IV inhibitor or glucagon like peptide-1 analogue) may improve postprandial hypertriglyceridemia. Since the accumulation of CM remnants correlates to impaired lipid and glucose metabolism and atherosclerotic cardiovascular events, further studies are required to investigate the characteristics, physiological activities, and functions of CM remnants for the development of new interventions to reduce atherogenicity.

Antihyperlipidemic activity of adenosine triphosphate in rabbits fed a high-fat diet and hyperlipidemic patients

Context Recently, adenosine triphosphate (ATP) was occasionally found to decrease the triglyceride (TG) levels in several hyperlipidemic patients in our clinical practice. Objective The study investigates the anti-hyperlipidemic effects of ATP in a high-fat fed rabbit model and hyperlipidemic patients. Materials and methods Twenty-four rabbits were randomly divided into three groups of eight animals each as follows: normal diet, high-fat diet and high-fat diet + ATP group. ATP supplementation (40 mg/day) was started at the 20th day and lasted for 10 days. Serum concentrations of total cholesterol (TC), TG, LDL-C, HDL-C were measured on the 20th day and 30th day. Heart, liver and aorta were subjected histopathological examination. Twenty outpatients diagnosed primary hyperlipidemia took ATP at a dose of 60 mg twice a day for 1 week. Results Feeding rabbits with a high-fat diet resulted in a significant elevation of lipid parameters including TC, TG, LDL-C, VLDL-C compared to the normal diet group (p < 0.01). ATP treatment significantly decreased serum TG level (p < 0.01), whilst other parameters remained statistically unaltered. Meanwhile, ATP significantly reduced the thickness of fat layer in cardiac epicardium (p < 0.05) and pathological gradation of ballooning degeneration in hepatocytes (p < 0.05). After taking ATP for 1 week, hyperlipidemia patients exhibited a significant decrease of TG (p < 0.01), but other lipid parameters had no significant change. Discussion and conclusion The study indicates that ATP selectively decreases serum TG levels in high-fat diet rabbits and hyperlipidemic patients. Therefore, ATP supplementation may provide an effective approach to control TG level.

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.

Chylomicrons: Advances in biology, pathology, laboratory testing, and therapeutics

The adequate absorption of lipids is essential for all mammalian species due to their inability to synthesize some essential fatty acids and fat-soluble vitamins. Chylomicrons (CMs) are large, triglyceride-rich lipoproteins that are produced in intestinal enterocytes in response to fat ingestion, which function to transport the ingested lipids to different tissues. In addition to the contribution of CMs to postprandial lipemia, their remnants, the degradation products following lipolysis by lipoprotein lipase, are linked to cardiovascular disease. In this review, we will focus on the structure-function and metabolism of CMs. Second, we will analyze the impact of gene defects reported to affect CM metabolism and, also, the role of CMs in other pathologies, such as atherothrombotic cardiovascular disease and diabetes mellitus. Third, we will provide an overview of the laboratory tests currently used to study CM disorders, and, finally, we will highlight current treatments in diseases affecting CMs.

Alterations of intestinal lipoprotein metabolism in diabetes mellitus and metabolic syndrome

Diabetes and metabolic syndrome are associated with abnormal postprandial lipoprotein metabolism, with a significant delay in the clearance of many lipid parameters, including triglycerides and chylomicrons. Abnormal concentrations of plasma lipids can result from changes in the production, conversion, or catabolism of lipoprotein particles. Whereas the liver is involved in controlling serum lipid levels through synthesis of liver derived triglyceride-rich lipoproteins and low-density lipoprotein metabolism, the intestine also has a major role in lipoprotein production. Postprandial lipemia results from increases in apoB-48 availability, lipogenesis, and the synthesis and absorption of cholesterol in the enterocytes. Increased intestinal lipoprotein production prolongs postprandial lipemia in patients with diabetes and MetS, and may contribute directly to atherogenesis in these patients.

Lipoprotein effects of incretin analogs and dipeptidyl peptidase 4 inhibitors

Elevated post-prandial lipoprotein levels are common in patients with type 2 diabetes. Post-prandial lipoprotein alterations in type 2 diabetics are widely believed to drive inflammation and are considered a major risk factor for cardiovascular disease in diabetic patients. The incretins glucagon like peptide-1 (GLP-1) and glucose insulinotropic peptide (GIP) modulate post-prandial lipoproteins through a multitude of pathways that are independent of insulin and weight loss. Evidence from both animal models and humans seems to suggest an important effect on triglyceride rich lipoproteins (Apo48 containing) with little to no effects on other lipoproteins at least in humans. Dipeptidyl peptidase-4 (DPP4) inhibitors also appear to share these effects suggesting an important role for incretins in these effects. In this review, we will summarize lipid modulating effects of incretin analogs and DPP-4 inhibitors in both animal models and human studies and provide an overview of mechanisms responsible for these effects.

Circulating PCSK9 is a strong determinant of plasma triacylglycerols and total cholesterol in homozygous carriers of apolipoprotein ε2

Plasma PCSK9, an important determinant of LDL-receptor degradation, is strongly related to total cholesterol and triacylglycerol levels in homozygous carriers of the apolipoprotein ε2 allele. This observation provides new insight into the pathogenesis of type III hyperlipidaemia and its treatment.

Elevated remnant lipoproteins may increase subclinical CVD risk in pre-pubertal children with obesity: a case-control study

OBJECTIVES

Current clinical guidelines to assess paediatric cardiovascular disease (CVD) risk heavily rely on cholesterol parameters that are generally normal for obese children. Remnant lipoproteins have emerged as a critical CVD risk factor particularly in adults with normolipidemia. We assessed remnant lipoprotein concentration (measured by apolipoprotein [apo] B48) and its relationship with other traditional CVD risk biomarkers in pre-pubertal children with obesity.

METHODS

Pre-pubertal children (n = 78) with obesity (n = 39, 9.9 ± 0.3 years old) as well as sex-matched normal-weight controls (n = 39, 9.8 ± 0.3 years) were assessed for anthropometry, blood pressure and fasting plasma biochemical parameters for remnant lipoprotein, lipid and glucose/insulin metabolism, and inflammatory status.

RESULTS

Children with obesity had striking 2-fold higher apoB48-containing remnant lipoproteins concentrations relative to normal-weight peers; the magnitude of elevation in the remnant lipoproteins is comparable to the levels previously reported for adults with established CVD and type-2 diabetes. Fasting apoB48 was positively correlated with fasting triglyceride concentration in children with obesity (r = 0.51, P < 0.001) and their normal-weight peers (r = 0.45, P < 0.01). Traditional CVD biomarkers including low-density lipoprotein cholesterol showed no difference between groups and remained within the normal range for a paediatric population.

CONCLUSION

Elevated apoB48-containing remnant lipoprotein is a stronger biomarker for paediatric CVD risk compared to traditional cholesterol parameters and may be associated with early adaptation of the intestine during obesity. Further investigation of abnormalities associated with the secretion and/or clearance of atherogenic remnant lipoproteins during the postprandial state may yield insight into our understanding of and therapeutic targets for managing risk for CVD in children with obesity.

The Role of Endocannabinoid System Blockade in the Treatment of the Metabolic Syndrome

This review considers the use of the first selective blocker of the cannabinoid receptor type 1, rimonabant, to reduce weight and improve cardiovascular disease risk factors in obese patients with metabolic syndrome or multiple cardiovascular disease risk factors. In 4 large trials-Rimonabant in Obesity (RIO)-Lipids, RIO-Europe, RIO-North America, and RIO-Diabetes-after 1 to 2 years of treatment, rimonabant (20 mg/day) led to a significantly greater weight loss and reduction in waist circumference compared with placebo. Treatment with rimonabant was also associated with other favorable changes, including better glycemic control in type 2 diabetes mellitus, improved lipid profile, reduced blood pressure, increased adiponectin levels, fall in high-sensitivity C-reactive protein concentrations, and an overall decrease in the prevalence of the metabolic syndrome. Initial experience with rimonabant shows that it is generally well tolerated with the most common side effect of mild nausea. Rimonabant may be a useful adjunct to lifestyle and behavior modification in the treatment of obese subjects with metabolic syndrome or multiple cardiometabolic risk factors.

Upregulation of hepatic LRP1 by rosiglitazone: a possible novel mechanism of the beneficial effect of thiazolidinediones on atherogenic dyslipidemia

Hepatic LDL receptor-related protein 1 (LRP1) plays a role in the clearance of circulating remnant lipoproteins. In this study, we investigated the effect of rosiglitazone treatment on the expression and function of hepatic LRP1. HepG2 cells were incubated with various concentrations of rosiglitazone. Male Long-Evans Tokushima Otsuka (LETO) rats and Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats were treated with rosiglitazone for 5 weeks. The expression and function of LRP1 in HepG2 cells and liver samples of rats were analyzed. LRP1 mRNA and protein expressions were increased by 0.5 and 5  μM rosiglitazone in HepG2 cells. However, at concentrations above 50  μM rosiglitazone, LRP1 mRNA and protein expressions did not change compared with those in nontreated cells. Reporter assay showed that 0.5 and 5  μM rosiglitazone increased the transcriptional activity of the LRP1 promoter in HepG2 cells. The uptake of apolipoprotein E through LRP1 in HepG2 cells was also increased by rosiglitazone. Hepatic LRP1 was reduced in OLETF rats compared with that of LETO rats and rosiglitazone treatment increased hepatic LRP1 in OLETF rats. A high glucose condition (25  mM glucose in culture media) reduced the expression of LRP1 in HepG2 cells, and this reduced LRP1 expression was recovered with rosiglitazone. In conclusion, our data suggest that decreased hepatic LRP1 in a diabetic condition is associated with the development of atherogenic dyslipidemia and that increased hepatic LRP1 by thiazolidinediones could contribute to an improvement in atherogenic lipid profiles in diabetic patients.

Postprandial lipoprotein metabolism: VLDL vs chylomicrons

Since Zilversmit first proposed postprandial lipemia as the most common risk of cardiovascular disease, chylomicrons (CM) and CM remnants have been thought to be the major lipoproteins which are increased in the postprandial hyperlipidemia. However, it has been shown over the last two decades that the major increase in the postprandial lipoproteins after food intake occurs in the very low density lipoprotein (VLDL) remnants (apoB-100 particles), not CM or CM remnants (apoB-48 particles). This finding was obtained using the following three analytical methods; isolation of remnant-like lipoprotein particles (RLP) with specific antibodies, separation and detection of lipoprotein subclasses by gel permeation HPLC and determination of apoB-48 in fractionated lipoproteins by a specific ELISA. The amount of the apoB-48 particles in the postprandial RLP is significantly less than the apoB-100 particles, and the particle sizes of apoB-48 and apoB-100 in RLP are very similar when analyzed by HPLC. Moreover, CM or CM remnants having a large amount of TG were not found in the postprandial RLP. Therefore, the major portion of the TG which is increased in the postprandial state is composed of VLDL remnants, which have been recognized as a significant risk for cardiovascular disease.

Predictive value of remnant lipoprotein for cardiovascular events in patients with coronary artery disease after achievement of LDL-cholesterol goals

OBJECTIVES

Triglycerides-rich lipoproteins are related to residual cardiovascular risk in patients on lipid-lowering treatment who achieve low-density lipoprotein cholesterol (LDL-C) goals. This study examined the predictive value of remnant lipoprotein levels for cardiovascular events in patients with coronary artery disease (CAD) with LDL-C levels <100mg/dL on lipid-lowering therapy.

METHODS

Serum levels of remnant lipoproteins (remnant-like lipoprotein particles cholesterol; RLP-C) were measured by an immunoseparation method in 560 patients with CAD who had LDL-C levels <100mg/dL on lipid-lowering therapy, including statin (58%), fibrate (13%) or diet only (29%). All the patients were followed prospectively for a period of ≤ 36 months or until occurrence of one of the following events: cardiac death, non fatal myocardial infarction, unstable angina requiring coronary revascularization, or ischemic stroke.

RESULTS

During a mean follow-up period of 33 months, 40 events occurred. Stepwise multivariate Cox proportional hazard analysis showed that RLP-C was a significant predictor of cardiovascular events after adjustment for known risk factors and lipid variables including triglycerides, non-high-density lipoprotein (HDL)-C, and total apolipoprotein B (HR 1.53, 95% CI 1.35-1.97, p<0.01). The c-statistics showed that addition of RLP-C had a greater incremental effect on the predictive value of conventional risk factors than addition of non-HDL-C or total apolipoprotein B.

CONCLUSIONS

RLP-C was superior to non-HDL-C for predicting cardiovascular events in CAD patients with LDL-C levels <100mg/dL on lipid-lowering treatment. Remnant lipoprotein may therefore be an important target for residual risk reduction after LDL-C goals on lipid lowering therapy.

Efficacy of fibrates for cardiovascular risk reduction in persons with atherogenic dyslipidemia: a meta-analysis

BACKGROUND

Recent data suggest that non-targeted treatment with fibrates modestly reduces the risk of incident cardiovascular events. However the effect of fibrate treatment may be particularly beneficial in patients with guideline-endorsed indications for therapy due to evidence of atherogenic dyslipidemia. We conducted a systematic review and meta-analysis to investigate the influence of fibrates on vascular risk reduction in persons with atherogenic dyslipidemia.

METHODS

Systematic search of Pubmed, CENTRAL and recent reviews was conducted to identify atherogenic dyslipidemia (serum high density lipoprotein cholesterol [HDL-C]<40 mg/dl or triglycerides >200 mg/dl) cohorts from randomized controlled trials. RR with 95% CI was used as a measure of the association between fibrate therapy and risk of cardiovascular diseases, after pooling data across trials in a random-effects model.

RESULTS

Six trials met selection criteria. Compared to placebo, the greatest benefit with fibrate treatment was seen in 7389 subjects with high triglycerides, fibrate therapy reduced risk of vascular events (RR 0.75, 95% CI 0.65 to 0.86, P<0.001); and in 5068 subjects with both high triglycerides and low HDL-C (RR 0.71, 95% CI 0.62 to 0.82, P<0.001). Less benefit was noted in 15,303 subjects selected for low HDL-C (RR 0.84, 95% CI 0.77 to 0.91, P<0.001). Among 9872 subjects with neither high triglycerides nor low HDL-C, fibrate therapy did not reduce subsequent vascular events (RR 0.96, 95% CI 0.85 to 1.09, P=0.53).

CONCLUSIONS

Fibrate treatment directed at markers of atherogenic dyslipidemia substantially reduce subsequent vascular event risk.

Pokkuri Death Syndrome; sudden cardiac death cases without coronary atherosclerosis in South Asian young males

Sudden death is one of the major concerns in forensic medicine. Especially when the deceased is a young subject without significant history, the case will be of major interest to the authorities. Sudden unexplained cardiac death has been known as "Pokkuri Death Syndrome" (PDS) in Japan, "Lai Tai" in Thailand, "Bangungut" in the Philippines, "Dream Disease" in Hawaii, and "Sudden Unexpected Nocturnal Death Syndrome" among South Asian immigrants in the USA. However, the clinical and pathological features of these sudden death cases, especially the characteristics of no coronary atherosclerosis, are surprisingly similar and mainly occur among Southeast Asian young males during sleep in the midnight. In this manuscript, we have reviewed the pathological characteristics and the possible mechanism of death in PDS cases, which were associated with significantly elevated remnant lipoproteins in plasma as revealed from our studies during the past 15 years in Japan. Although elevated plasma remnant lipoproteins have been known to be strongly atherogenic, coronary atherosclerosis was not observed in PDS cases. PDS cases were shown to be an interesting cardiovascular disease death discovered in forensic medicine research, which may suggest the difference between the occurrence of cardiovascular events and the severity of coronary atherosclerosis as separate factors. These observations in PDS cases suggest the possibility that the intervention could be more targeted to suppress the cardiovascular events rather than to slow down the progression of atherosclerosis, which is now most extensively targeted for the therapy of cardiovascular disease in Western countries.

Methods to assess impaired post-prandial metabolism and the impact for early detection of cardiovascular disease risk

Post-prandial lipaemia has emerged as a key contributor to cardiovascular disease (CVD) risk and progression. Specifically, delayed clearance of chylomicrons (CM) and their remnants increase the delivery of triglyceride and cholesteryl ester to the vessel wall and can accelerate the progression of atherosclerosis, which may be particularly pertinent to individuals with insulin resistance and/or obesity. As the number of studies linking post-prandial metabolism and chronic disease increases, interest has grown in the use of parameters reflecting CM metabolism as a possible indicator of early CVD risk. This, in turn has raised the question of what method might be most appropriate to detect CM and their remnants in plasma accurately. However, the handful of techniques able to measure CM metabolism (triglyceride-rich lipoprotein fractions; remnant-lipoprotein cholesterol; retinyl esters, CM-like emulsion; sodium dodecyl sulphate-polyacrylamide gel electrophoresis; immunoblotting, enzyme-linked immunoabsorbent assays; C(13) breath test; capillary finger prick) differ in their specificity, cost and applicability in research and in the clinical setting. In this review, we explore the scientific and clinical implications of CM methodology to better understand early risk assessment of CVD. We raise ongoing issues of the need to appreciate differential separation of very low-density lipoprotein and CM fractions, as well as to identify the technical basis for imprecision between assays for apolipoprotein B48. We also highlight emerging issues with respect to the practicality of measuring post-prandial metabolism in large clinical studies and offer opinions on the appropriateness of existing techniques in this field.

Pediatric triglycerides predict cardiovascular disease events in the fourth to fifth decade of life

To assess relationships between pediatric lipids and subsequent cardiovascular disease (CVD) in the fourth to fifth decades, we conducted 22- to 31-year follow-up studies (1998-2003) in former schoolchildren first studied in 1973-1976. The follow-up included 53% of eligible former subjects. We compared pediatric and adult body mass (in kilograms per square meter) and lipids in 19 cases with at least 1 CVD event and in 789 CVD event-free subjects. Mean +/- SD age was 12.3 +/- 3.3 years at entry and 38.5 +/- 3.8 years at follow-up. Mean age at the first CVD event was 37.1 +/- 4.9 years. The major novel finding of our study was that childhood triglycerides (TG) were consistently and independently associated with young adult CVD. The distributions of both childhood and adult TG were shifted to higher levels in the cases than controls. Of the 19 cases, 7 (37%) had childhood TG greater than the pediatric 95th percentile (153 mg/dL); and 6 of these 7 had high TG (>/=150 mg/dL) at adult follow-up. Overall, 61% of cases had high TG as adults. After adjusting for age, sex, and race, by analysis of variance, cases had higher TG levels both in childhood and in young adulthood. A bootstrapping method and the Cox proportional hazard analysis were used to predict CVD in the cohort with explanatory variables sex; race; childhood body mass index, low-density lipoprotein, log high-density lipoprotein cholesterol, and log TG; and adult cigarette smoking and type 2 diabetes mellitus. Childhood TG level was a significant, independent explanatory variable for young adult CVD hazard (hazard ratio, 5.35; 95% confidence interval, 1.69-20.0 for each 1-unit increase in natural logarithm scale) along with adult type 2 diabetes mellitus (hazard ratio, 19.4; 95% confidence interval, 4.24-114.2). Pediatric hypertriglyceridemia appears to be a significant, independent, potentially reversible correlate of young adult CVD.

Remnant lipoproteins as strong key particles to atherogenesis

Recent epidemiologic studies have revealed that hypertriglyceridemia is associated with atherosclerosis independent of other coronary risk factors. However, it is difficult to select patients at high risk for coronary artery disease using only serum triglyceride levels compared with low-density lipoprotein cholesterol levels since multiple factors are associated with elevating triglycerides. Atherosclerotic diseases with high triglyceride levels can be found in patients with familial combined hyperlipidemia, diabetes mellitus, and metabolic syndrome, in which remnant lipoproteins accumulate in the circulating blood. Recent researches have paid attention to remnant lipoproteins as atherogenic particles with the development of methods for measuring remnant cholesterol levels and apolipoprotein B-48 levels directly from human serum. Measurement of these parameters in addition to serum triglycerides may help to distinguish high-risk patients and enable us to prevent or suppress the progression of atherosclerotic diseases in those patients. However, questions remain to be answered to evaluate the significance of remnant lipoproteins. Here, we focus on three issues: the underlying problems in measuring remnant lipoprotein cholesterol, the assessment of postprandial hyperlipidemia as an atherogenic condition, and finally a review of our experimental and clinical findings about the mechanisms by which remnant lipoproteins induce atherosclerosis.

The correlation between TG vs remnant lipoproteins in the fasting and postprandial plasma of 23 volunteers

BACKGROUND

Two recent publications report that non-fasting triglycerides concentrations in plasma are more predictive of cardiovascular events than conventional measurements of fasting triglycerides. While these observations are consistent with the previous studies, direct correlations between remnant lipoprotein triglyceride (RLP-TG) and remnant lipoprotein cholesterol (RLP-C), which are also considered to be risk factors for cardiovascular disease, and fasting and postprandial TG have not been investigated.

METHODS

On four different days, both fasting and postprandial blood samples were collected from twenty-three overweight to obese men and women at UC Davis and analyzed for plasma concentrations of TG, RLP-C and RLP-TG.

RESULTS

Significantly higher correlations between plasma TG and RLPs were observed in the postprandial state (RLP-C r2 = 0.85; RLP-TG r2 = 0.92) than in the fasting state (RLP-C r2 = 0.61; RLP-TG r2 = 0.73). The differences in the correlations between the fasting and postprandial TG and RLPs were statistically significant (p < 0.001). The increase of RLP-TG (postprandial RLP-TG minus fasting RLP-TG) consisted of approximately 80% of the total increase of TG (postprandial TG minus fasting TG).

CONCLUSION

Postprandial TG vs remnant lipoprotein concentrations were significantly more correlated when compared with fasting TG vs RLP concentrations. The increased TG in the postprandial state mainly consisted of TG in remnant lipoproteins. Therefore, the increased sensitivity of non-fasting TG in predicting the risk for cardiovascular events may be directly explained by the increase of remnant lipoproteins in the postprandial state.