Serum cholesterol and triglycerides in patients suffering from ischemic heart disease and in healthy subjects

Framingham risk scores for determination the 10-year risk of cardiovascular disease in participants with and without the metabolic syndrome: results of the Fasa Persian cohort study

BACKGROUND

Metabolic syndrome (MetS) is a cluster of risk factors and the Framingham risk score (FRS) is a useful metric for measuring the 10-year cardiovascular disease (CVD) risk of the population. The present study aimed to determine the 10-year risk of cardiovascular disease using the Framingham risk score in people with and without MetS in a large Iranian cohort study.

METHODS

This cross-sectional study was done using the Fasa cohort. Participants aged ≥ 35 years old were recruited to the study from 2015 to 2016. The FRS was calculated using age, sex, current smoking, diabetes, systolic blood pressure (SBP), total cholesterol, and high-density lipoprotein (HDL) cholesterol. MetS was defined as the presence of three or more of the MetS risk factors including triglyceride (TG) level ≥ 150 mg dl- 1, HDL level < 40 mg dl- 1 in men and < 50 mg dl- 1 in women, systolic/diastolic blood pressure ≥ 130/≥85 mmHg or using medicine for hypertension, fasting blood sugar (FBS) level ≥ 100 mg dl- 1 or using diabetes medication and abdominal obesity considered as waist circumference (WC) ≥ 88 cm for women and ≥ 102 cm for men. Multiple logistic regressions were applied to estimate the 10- year CVD risk among people with and without MetS.

RESULTS

Of 8949 participants, 1928 people (21.6%) had MetS. The mean age of the participants with and without Mets was 50.4 ± 9.2 years and 46.9 ± 9.1 years respectively. In total 15.3% of participants with MetS and 8.0% of participants without MetS were in the high-risk category of 10-year CVD risk. Among participants with MetS gender, TG, SBP, FBS and in people without MetS gender, TG, SBP, FBS, and HDL showed strong associations with the predicted 10-year CVD risk.

CONCLUSION

Male sex and increased SBP, TG, and FBS parameters were strongly associated with increased 10-year risk of CVD in people with and without MetS. In people without MetS, reduced HDL-cholestrol was strongly associated with increased 10-year risk of CVD. The recognition of participant's TG, blood pressure (BP), FBS and planning appropriate lifestyle interventions related to these characteristics is an important step towards prevention of CVD.

Late-afternoon endurance exercise is more effective than morning endurance exercise at improving 24-h glucose and blood lipid levels

BACKGROUND

Glucose and lipid tolerance reportedly exhibit diurnal variations, being lower in the evening than in the morning. Therefore, the effects of exercise on glucose and blood lipid levels at different times of the day may differ. This study aimed to investigate the effects of short-term endurance exercise intervention in the morning versus late afternoon on 24-h blood glucose variability and blood lipid levels.

METHODS

Twelve healthy young men participated in a randomized crossover trial. The participants were assigned to morning (09:00-11:00) or late afternoon (16:00-18:00) endurance exercise for a week, consisting of supervised exercise sessions on Mondays, Wednesdays, and Fridays. In the morning and evening trials, the participants walked for 60 min on a treadmill at approximately 60% of maximal oxygen uptake (VO_2max). Following a 2-week wash-out period, the participants performed the exercise training regimen at another time point. Continuous glucose monitoring was used to evaluate blood glucose fluctuations during each 24-h trial period. Blood samples were collected before and after each intervention to examine blood lipid and hormonal responses.

RESULTS

Examination of the area under the curve (AUC) of the glucose level changes for 24 h after the late afternoon versus morning exercise intervention revealed significantly lower values for the former versus the latter (P < 0.01). The AUC of glucose level changes after each meal was also lower after the late afternoon versus morning intervention, and significantly lower values were observed in the late afternoon versus morning trial for breakfast and dinner (P < 0.05, P < 0.01). In addition, a significant decrease in triglycerides (TG) and TG/high-density lipoprotein cholesterol (HDL-C) was noted after versus before the late afternoon intervention (P < 0.05).

CONCLUSIONS

These results suggest that late afternoon endurance exercise is more effective than morning endurance exercise at improving 24-h glucose and triglyceride levels.

Levels of miR-130b-5p in peripheral blood are associated with severity of coronary artery disease

BACKGROUND

Although patients with coronary artery disease (CAD) have a high mortality rate, the pathogenesis of CAD is still poorly understood. During the past decade, microRNAs (miRNAs) have emerged as new, potential diagnostic biomarkers in several diseases, including CAD. This study aimed to investigate the expression profiles of miRNAs in individuals with CAD and non-CAD.

METHODS AND RESULTS

The Agilent's microarray analyses were performed to compare the whole blood miRNA profile of selected individuals with severe CAD (n = 12, ≥ 90% stenosis) and non-CAD (n = 12, ≤ 20 stenosis). Expressions of selected differentially expressed miRNAs (DEMs) were analyzed for validation in individuals with critical CAD (n = 50) and non-CAD (n = 43) using real-time PCR. Target prediction tools were utilized to identify miRNA target genes. We identified 6 DEMs that were downregulated in CAD patients, which included hsa-miR-18a-3p and hsa-miR-130b-5p, that were analyzed for further testing. Expression levels of hsa-miR-130b-5p were found negatively correlated with SYNTAX score and stenosis in female CAD patients (p < 0.05). In addition, both miRNAs were found positively correlated with plasma HDL and inversely correlated with fasting triglyceride levels (p < 0.05). In linear regression analysis adjusted for several confounders, the correlations have remained statistically significant. Computational prediction of target genes indicated a relevant role of hsa-miR-130b-5p and hsa-miR-18a-3p in modulating the expression of genes associated with cardiovascular diseases.

CONCLUSION

Our findings highlight a significantly different pattern of miRNA expression in CAD patients in microarray results. Hsa-miR-18a-3p and hsa-miR-130b-5p might serve as biomarkers of CAD development and progression and warrant further attention.

Predictive Value of the Atherogenic Index of Plasma (AIP) for the Risk of Incident Ischemic Heart Disease among Non-Diabetic Koreans

The atherogenic index of plasma (AIP), composed of triglycerides and high-density lipoprotein cholesterol, is a novel critical marker for assessing the risk of atherogenicity and cardiometabolic health. We aimed to prospectively study the association between AIP and incident ischemic heart disease (IHD) risk in a large cohort of non-diabetic Korean adults. Data were assessed from 17,944 participants without diabetes from the Health Risk Assessment Study (HERAS) and Korea Health Insurance Review and Assessment (HIRA) data. The participants were divided into four groups according to AIP quartiles, calculated as log (triglyceride/high-density lipoprotein cholesterol). We prospectively assessed hazard ratios (HRs) with 95% confidence intervals (CIs) for IHD using multivariate Cox proportional-hazard regression models over a 50-month period that followed the baseline survey. During the follow-up period, 332 participants (1.9%) developed IHD. HRs of IHD for AIP quartiles 2-4 were 1.58 (95% CI, 1.03-2.43), 1.82 (95% CI, 1.20-2.78), and 2.11 (95% CI, 1.37-3.24) after adjusting for age, sex, body mass index, smoking status, alcohol intake, physical activity, mean arterial blood pressure, fasting plasma glucose, high-sensitivity C-reactive protein level, and hypertension medication. Higher AIP levels may precede and predict the development of IHD in non-diabetic Korean adults.

X‑irradiation induces acute and early term inflammatory responses in atherosclerosis‑prone ApoE‑/‑ mice and in endothelial cells

Thoracic radiotherapy is an effective treatment for many types of cancer; however it is also associated with an increased risk of developing cardiovascular disease (CVD), appearing mainly ≥10 years after radiation exposure. The present study investigated acute and early term physiological and molecular changes in the cardiovascular system after ionizing radiation exposure. Female and male ApoE^‑/‑ mice received a single exposure of low or high dose X‑ray thoracic irradiation (0.1 and 10 Gy). The level of cholesterol and triglycerides, as well as a large panel of inflammatory markers, were analyzed in serum samples obtained at 24 h and 1 month after irradiation. The secretion of inflammatory markers was further verified in vitro in coronary artery and microvascular endothelial cell lines after exposure to low and high dose of ionizing radiation (0.1 and 5 Gy). Local thoracic irradiation of ApoE^‑/‑ mice increased serum growth differentiation factor‑15 (GDF‑15) and C‑X‑C motif chemokine ligand 10 (CXCL10) levels in both female and male mice 24 h after high dose irradiation, which were also secreted from coronary artery and microvascular endothelial cells in vitro. Sex‑specific responses were observed for triglyceride and cholesterol levels, and some of the assessed inflammatory markers as detailed below. Male ApoE^‑/‑ mice demonstrated elevated intercellular adhesion molecule‑1 and P‑selectin at 24 h, and adiponectin and plasminogen activator inhibitor‑1 at 1 month after irradiation, while female ApoE^‑/‑ mice exhibited decreased monocyte chemoattractant protein‑1 and urokinase‑type plasminogen activator receptor at 24 h, and basic fibroblast growth factor 1 month after irradiation. The inflammatory responses were mainly significant following high dose irradiation, but certain markers showed significant changes after low dose exposure. The present study revealed that acute/early inflammatory responses occurred after low and high dose thoracic irradiation. However, further research is required to elucidate early asymptomatic changes in the cardiovascular system post thoracic X‑irradiation and to investigate whether GDF‑15 and CXCL10 could be considered as potential biomarkers for the early detection of CVD risk in thoracic radiotherapy‑treated patients.

The triglyceride paradox in the mortality of coronary artery disease

Background

The role of triglyceride (TG) in secondary prevention of patients with coronary artery disease (CAD) was debated. In the present study, we assessed the association between admission TG levels and long-term mortality risk in CAD patients.

Methods

A retrospective analysis was conducted from a single registered database. 3061 consecutive patients with CAD confirmed by coronary angiography were enrolled and were grouped into 3 categories by the tertiles of admission serum TG levels. The primary end point in this study was all-cause mortality and the secondary end point was cardiovascular mortality.

Results

The mean follow-up time was 26.9 ± 13.6 months and death events occurred in 258 cases and cardiovascular death events occurred in 146 cases. Cumulative survival curves indicated that the risk of all-cause death decreased with increasing TG level (Tertile 1 vs. Tertile 2 vs. Tertile 3 = 10.3% vs. 8.6% vs. 6.3%, log rank test for overall p = 0.001). Cox regression analysis showed an independent correlation between TG level and risk of all-cause mortality [hazard ratio (HR) 0.71, 95% confidence interval (CI) 0.58–0.86] and cardiovascular mortality (HR 0.67, 95% CI 0.51–0.89) in total patients with CAD. Subgroup analysis found the similar results in patients with acute coronary syndrome and acute myocardial infarction.

Conclusions

This study found an inverse association between TG levels and mortality risk in CAD patients, which suggests that the “TG paradox” may exist in CAD patients.

Trial registration

ChiCTR, ChiCTR-OOC-17010433. Registered 17 February 2017 - Retrospectively registered.

Quinoa Seed Lowers Serum Triglycerides in Overweight and Obese Subjects: A Dose-Response Randomized Controlled Clinical Trial

Background: Quinoa (Chenopodium quinoa) is a pseudo-cereal originally cultivated in the Andean region. The popularity of its seeds has increased in recent years due to the claims of health benefits and superfood qualities. Studies to date on the health benefits of quinoa have been restricted to animal models, and the results provide weak to moderate evidence to support improved plasma lipid profiles. Clinical trials in humans to examine the claims of health benefits of quinoa are limited to a few prospective studies and one randomized trial carried out in postmenopausal women. To our knowledge, no studies have been conducted in the general population. Objective: The objective of this randomized clinical trial was to investigate the effect of different quinoa doses (25 and 50 g/d) on body composition, serum lipids and hormones, and nutrient intakes in overweight and obese humans. Methods: This was a dose-response randomized, controlled, single-blind trial with a parallel design (1 control and 2 treatment groups) that compared the effect of 25 and 50 g quinoa/d in 50 overweight and obese participants over a 12-wk intervention period. Results: Body composition, nutrient intake, and total, LDL, and HDL cholesterol were not significantly altered by quinoa consumption (P > 0.05). Mean serum triglyceride (TG) concentration was reduced significantly in the 50-g quinoa group from 1.14 to 0.72 mmol/L at 12 wk (P < 0.05). The prevalence of metabolic syndrome (MetS) was also reduced in this group by 70%. No significant changes in TGs were observed in the control and 25-g quinoa groups. The prevalence of MetS was reduced by 40% (from n = 7 at baseline to n = 4 at 12 wk) in the 25-g group. Conclusions: The consumption of 50 g quinoa/d lowers serum TGs in overweight and obese participants and reduces the prevalence of MetS. This trial was registered at clinicaltrials.gov as UTN U1111-1175-470.

How do elevated triglycerides and low HDL-cholesterol affect inflammation and atherothrombosis?

This review article summarizes recent research into the mechanisms as to how elevated levels of triglyceride (TG) and low levels of high- density- lipoprotein cholesterol (HDL-C) contribute to inflammation and atherosclerosis. Evidence supports the role of TG-rich lipoproteins in signaling mechanisms via apolipoproteins C-III and free fatty acids leading to activation of NFKβ, VCAM-1 and other inflammatory mediators which lead to fatty streak formation and advanced atherosclerosis. Moreover, the cholesterol content in TG-rich lipoproteins has been shown to predict CAD risk better than LDL-C. In addition to reverse cholesterol transport, HDL has many other cardioprotective effects which include regulating immune function. The "functionality" of HDL appears more important than the level of HDL-C. Insulin resistance and central obesity underlie the pathophysiology of elevated TG and low HDL-C in metabolic syndrome and type 2 diabetes. Lifestyle recommendations including exercise and weight loss remain first line therapy in ameliorating insulin resistance and the adverse signaling processes from elevated levels of TG-rich lipoproteins and low HDL-C.

Role of fibric acid derivatives in the management of risk factors for coronary heart disease

Although elevated low-density lipoprotein (LDL)-cholesterol is a well established coronary heart disease (CHD) risk factor, the ability to adequately discriminate high-risk individuals by this risk factor alone is limited and other metabolic risk variables are known to modulate CHD risk. For instance, it has been reported that the cluster of metabolic disturbances observed among individuals with abdominal obesity, the so-called metabolic syndrome, is associated with a substantially increased risk of CHD. Among the features of the dyslipidaemic profile observed in these individuals, the high triglyceride-low high-density lipoprotein (HDL)-cholesterol dyslipidaemia is predictive of an elevated risk of CHD. Fibric acid derivatives (fibrates) have been used in clinical practice for more than 2 decades as a class of agents known to decrease triglyceride levels while substantially increasing HDL-cholesterol levels, with a limited but significant additional lowering effect on LDL-cholesterol levels. Although the clinical benefits of HMG-CoA reductase inhibitors (statins) have been well documented by primary and secondary prevention trials that justify their widespread use, it was not until the publication of the VA-HIT (Veterans Affairs High-Density Lipoprotein Intervention Trial) that the relevance of identifying HDL-cholesterol as a therapeutic target to reduce the risk of recurrent CHD events was finally confirmed. The clinical benefits of fibrate therapy are especially important in the subpopulation of patients with low HDL-cholesterol levels with the metabolic syndrome, particularly in patients with type 2 diabetes mellitus or in abdominally obese, hyperinsulinaemic patients. Evidence also suggests that there is a 'fibrate effect' that mediates the reduction in CHD risk beyond the favourable impact of these agents on HDL-cholesterol levels. This last notion is consistent with the pleiotropic effects of fibrates which are known to be related to their mechanisms of action. Through peroxisome proliferator-activated alpha-receptors, fibrates have a significant impact on the synthesis of several apolipoproteins (apo) and enzymes of lipoprotein metabolism as well as on the expression of several genes involved in fibrinolysis and inflammation. Fibrate therapy has been reported to decrease apo CIII levels (a powerful inhibitor of lipoprotein lipase) and increase apo AI levels, as well as to increase lipoprotein lipase activity. Such changes contribute to improve the catabolism of triglyceride-rich lipoproteins, leading to a substantial increase in HDL-cholesterol levels accompanied by a shift in the size and density of LDL particles (from small, dense LDL particles to larger, more buoyant cholesteryl ester-rich LDL). It is proposed that some of these pleiotropic effects could explain some of the clinical benefits of fibrate therapy beyond its HDL-raising properties, particularly among patients with abdominal obesity, hyperinsulinaemia or type 2 diabetes with both low HDL- and low/normal LDL-cholesterol levels.

Surfactant-based homogeneous assay for the measurement of triglyceride concentrations in VLDL and intermediate-density lipoprotein

BACKGROUND

Existing studies have demonstrated the clinical significance of triglyceride content in VLDL (VLDL-TG) and intermediate-density lipoprotein (IDL-TG). We developed a homogeneous assay protocol to directly measure VLDL-TG.

METHODS

Possible reagents and conditions for measuring VLDL-TG were comprehensively tested, and the "best" combination was determined. Healthy persons were instructed to consume a fatty meal after 15-h overnight fasting. Serum VLDL-TG + IDL-TG concentrations were measured using the proposed method. Patients with serum LDL-cholesterol concentrations > or = 3.62 mmol/L (140 mg/dL) were administered simvastatin at a daily dose of 5 mg, and serum VLDL-TG concentrations were then measured.

RESULTS

The combination of 2 nonionic surfactants played an important role in differentiating VLDL and IDL from other lipoproteins, probably via specific interactions with phospholipids and apolipoproteins. The regression line of the proposed method (y) and the ultracentrifugal assay (x) was: y = 0.98x + 0.31 mmol/L (r = 0.98; n = 73; P < 0.05). The difference between postprandial total TG and VLDL-TG concentrations was statistically significant (P < 0.05). After 8 weeks of therapy with simvastatin, total TG and LDL-cholesterol concentrations were 13.6% and 26.3% lower, respectively (P < 0.05), whereas VLDL-TG did not show any significant decrease.

CONCLUSION

Our homogeneous method can measure TG content in VLDL and IDL.

Evidence that triglycerides are an independent coronary heart disease risk factor

In the past, the relation between hypertriglyceridemia and coronary heart disease (CHD) has been uncertain. However, a recent multivariate analysis of 8-year follow-up data from the large-scale Prospective Cardiovascular Münster study found hypertriglyceridemia to be an independent risk factor for major coronary events after controlling for low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol. Hypertriglyceridemia combined with elevated LDL cholesterol and high LDL:HDL cholesterol ratio (>5) increased the CHD event risk by approximately sixfold. Similarly, a large meta-analysis of 17 prospective trials reported hypertriglyceridemia to be an independent risk factor for cardiovascular disease. In this study, an 88 mg/dl (1.0 mmol/L) increase in plasma triglyceride levels significantly increased the relative risk of cardiovascular disease by approximately 30% in men and 75% in women; the corresponding rates were somewhat lower (14% and 37%) but still statistically significant after adjustment for HDL cholesterol level. These data and observations from patients in the Helsinki Heart Study and the Stockholm Ischemic Heart study, that the greatest coronary benefit during lipid-lowering drug therapy occurred among hypertriglyceridemic patients, argue strongly for an independent role for hypertriglyceridemia in CHD risk. In the recent Veterans Affairs Cooperative Studies Program High-Density Lipoprotein Cholesterol Intervention Trial, the use of gemfibrozil to raise HDL cholesterol levels and lower levels of triglycerides without lowering LDL cholesterol levels reduced coronary events in men with established CHD, whereas preliminary results from the Bezafibrate Infarction Prevention Trial indicate a reduction in coronary end points in patients with elevated baseline triglyceride levels. To achieve the greatest possible reduction in CHD risk, antihyperlipidemic treatment strategies should also be aimed at reducing elevated triglycerides.

Secondary prevention by raising HDL cholesterol and reducing triglycerides in patients with coronary artery disease

BACKGROUND

Coronary heart disease patients with low high-density lipoprotein cholesterol (HDL-C) levels, high triglyceride levels, or both are at an increased risk of cardiovascular events, but the clinical impact of raising HDL-C or decreasing triglycerides remains to be confirmed.

METHODS AND RESULTS

In a double-blind trial, 3090 patients with a previous myocardial infarction or stable angina, total cholesterol of 180 to 250 mg/dL, HDL-C < or =45 mg/dL, triglycerides < or =300 mg/dL, and low-density lipoprotein cholesterol < or =180 mg/dL were randomized to receive either 400 mg of bezafibrate per day or a placebo; they were followed for a mean of 6.2 years. The primary end point was fatal or nonfatal myocardial infarction or sudden death. Bezafibrate increased HDL-C by 18% and reduced triglycerides by 21%. The frequency of the primary end point was 13. 6% on bezafibrate versus 15.0% on placebo (P=0.26). After 6.2 years, the reduction in the cumulative probability of the primary end point was 7.3%, (P=0.24). In a post hoc analysis in the subgroup with high baseline triglycerides (> or =200 mg/dL), the reduction in the cumulative probability of the primary end point by bezafibrate was 39.5% (P=0.02). Total and noncardiac mortality rates were similar, and adverse events and cancer were equally distributed.

CONCLUSIONS

Bezafibrate was safe and effective in elevating HDL-C levels and lowering triglycerides. An overall trend in a reduction of the incidence of primary end points was observed. The reduction in the primary end point in patients with high baseline triglycerides (> or =200 mg/dL) requires further confirmation.

Impaired myocardial vasodilation during hyperemic stress with dipyridamole in hypertriglyceridemia

OBJECTIVES

This study sought to investigate the specific role of hypertriglyceridemia in the myocardial hyperemic stress with dipyridamole/rest flow ratio (MDR).

BACKGROUND

Reduced MDR has been reported in hypercholesterolemic patients without evidence of ischemia. However, the specific role of hypertriglyceridemia in MDR has not been studied.

METHODS

Fifteen nondiabetic normocholesterolemic hypertriglyceridemic patients and 13 age-matched control subjects were studied. Myocardial blood flow (MBF) during dipyridamole administration and baseline MBF in hypertriglyceridemic patients and control subjects were measured using positron emission tomography and nitrogen-13 ammonia, after which the MDR was calculated.

RESULTS

Baseline MBF (ml/min per 100 g heart weight) in hypertriglyceridemic patients (mean +/- SD 73.6 +/- 24.1) did not differ significantly from that in control subjects (81.6 +/- 37.2). MBF during dipyridamole loading in hypertriglyceridemic patients (198 +/- 106) was significantly reduced compared with that in control subjects (313 +/- 176, p < 0.05), as was the MDR (2.71 +/- 1.07 vs. 3.73 +/- 1.14, respectively, p < 0.05). Spearman rank-order correlation analysis showed a significant relation between plasma triglyceride concentration and MDR (r = -0.466, asymptotic SE 0.157, p = 0.0125); however, no such significant relation was seen between total plasma cholesterol concentration and MDR (r = -0.369, asymptotic SE 0.130, p = 0.059).

CONCLUSIONS

Impaired myocardial vasodilation was suggested in hypertriglyceridemic patients without symptoms and signs of ischemia.

Altered myocardial vasodilatation in patients with hypertriglyceridemia in anatomically normal coronary arteries

Reduced myocardial vasodilatation (MVD) in hypercholesterolemics without overt coronary stenosis has been reported. However, the status of MVD in hypertriglyceridemics has not yet been clarified. The aim of this study was to investigate whether MVD is impaired in patients with hypertriglyceridemia without overt coronary stenosis. Twenty-three hypertriglyceridemics (10 normocholesterolemic hypertriglyceridemics [HTGs] and 13 mixed combined hyperlipidemics [MCHLs]) and 13 age-matched controls were studied. All patients were proven to have more than one normal coronary artery, as diagnosed by coronary angiography, and those segments that were perfused by anatomically normal coronary arteries were used in the study. Myocardial blood flow (MBF) during dipyridamole (DP) loading and baseline MBF were measured by using positron emission tomography and [13N]ammonia, after which MVD was calculated. Baseline MBF (mL.min(-1).100 g(-1)) was comparable among HTG (76.0+/-26.1), MCHL (77.0+/-26.1), and controls (80.3+/-38.5). However, MBF during DP loading was significantly lower in MCHL (159+/-52.5) than in control subjects (292+/-166, P<.01), while it was comparable in HTG (202+/-104) and controls. MVD was significantly reduced in both HTG (2.70+/-1.09, P<.05) and MCHL (2.07+/-.70, P<.01) compared with controls (3.73+/-1.14). MVD in MCHLs tended to be reduced compared with that in HTGs, but the difference was statistically insignificant (P=.08). There was a significant relationship between MVD and both plasma triglycerides (r=-.47, P<.01) and plasma total cholesterol (r=-.55, P<.01). When controls and HTGs were combined, the relationship between MVD and plasma total triglycerides became more prominent (r=-.55, P<.05), and the significant relationship between cholesterol level and MVD disappeared. Multivariate regression analysis has revealed that the triglyceride level (F=5.2, P<.05) was independently related to MVD (r=.69, P<.01). In conclusion, MVD was reduced in hypertriglyceridemics in anatomically normal coronary arteries. Hypertriglyceridemia is an independent factor for this abnormality.

Effects of gemfibrozil on very-low-density lipoprotein composition and low-density lipoprotein size in patients with hypertriglyceridemia or combined hyperlipidemia

To examine the effects of gemfibrozil on very-low-density lipoprotein (VLDL) composition and low-density lipoprotein (LDL) size, five men with hypertriglyceridemia (HTG) alone and five men with HTG and hypercholesterolemia (combined hyperlipidemia, CHLP) were randomized for 8 weeks to Lopid SR (slow-release gemfibrozil; two 600-mg tablets once per day) or placebo in a crossover study. Drug therapy versus placebo significantly decreased plasma triglyceride (68%), and VLDL (77%), and significantly increased high-density lipoprotein cholesterol (25%); total cholesterol, apolipoprotein B and lipoprotein[a] concentrations did not change significantly. With drug, mean total apoE in plasma was 53% lower in patients with HTG and 39% lower in patients with CHLP. Gemfibrozil significantly affected VLDL composition: protein increased 26%, molar ratio of apoE to apoB reduced 48%, apoC-II increased 19%, and apoC-III decreased 9%. LDL cholesteryl ester significantly increased with drug treatment. VLDL subfractions were separated and classified as heparin binding (VLDLR, apoE rich) or nonbinding (VLDLNR-1 and VLDLNR-2, both apoE poor). All VLDL subfractions were significantly lower with drug therapy, and the differences for total VLDL and for VLDL subfractions were greater in patients with HTG. With placebo, VLDLR accounted for 41.8% of VLDL in HTG and 49.0% of VLDL in CHLP, reduced to 27.6% and 38.6%, respectively, with gemfibrozil. Taken together, these results suggest that treatment with gemfibrozil reduces plasma concentrations of VLDL and alters the apoprotein composition of VLDL in a manner that may favor LDL- and VLDL-receptor-mediated clearance of the apoE-rich VLDL subfraction, thereby reducing TG-rich particle concentrations, and possibly reducing risk for coronary heart disease.

Triglycerides and HDL-cholesterol as risk factors for ischemic heart disease. Results from the Québec cardiovascular study

The relative importance of reduced plasma high density lipoprotein-cholesterol (HDL-C) levels and elevated plasma triglyceride (TG) concentrations as risk factors for ischemic heart disease (IHD) was examined in a sample of 2177 men from the Québec City suburbs. The sample included 202 men with known IHD. The relationship between HDL-C and TG levels, although significant (r = -0.49, P < 0.0001), was not linear, as most of the variation in HDL-C levels was observed within TG levels below 2.5 mmol/l. Reduced HDL-C (< 0.9 mmol/l) was a prevalent condition in men with IHD (50%) compared to those without IHD (30%). On the other hand 26% and 20% of men with and without IHD, respectively, had elevated TG levels (TG > 2.3 mmol/l). A 2-fold increase in prevalence odds ratio (OR) was observed in men with TG levels > 2.3 mmol/l (95% confidence intervals (CI) [1.2;3.3]). No residual association between elevated TG levels and IHD was found, however, after adjustment for HDL-C concentrations (OR 1.2, 95% CI 0.7;2.1). On the other hand, HDL-C remained a significant predictor of IHD after adjustment for other risk factors (OR 0.3, 95%, CI 0.2;0.6). Men with reduced HDL-C levels were also characterized by a cluster of risk factors such as obesity, diabetes mellitus and hypertension, which may contribute to increase the risk of IHD. Finally, the independent interpretation of cholesterol, TG or LDL-C levels may lead to an inadequate prediction of risk, as a large number of IHD patients showed a cluster of risk factors which included low HDL-C concentrations.

Plasma triglyceride and coronary heart disease

Although the literature on epidemiological associations between plasma triglyceride and CHD is not completely consistent, trends do emerge from the studies described here. First, the majority of observational studies demonstrate a significant univariate relation, although the results of case-control and cross-sectional studies are more uniform than those from prospective study designs. In many but not all studies, triglyceride remains a significant predictor of CHD in multivariate statistical analyses after controlling for TC or LDL-C. Perhaps the least consistent result is that the triglyceride association does not persist in some analyses controlling for HDL-C, while in other studies, the association remains significant. Although most studies have been conducted in men, the studies providing data on women, normocholesterolemic subjects, and diabetic subjects have generally found triglyceride to be, at the very least, a univariate risk factor. The results of intervention trials differ considerably, but no such study to date has been specifically designed to evaluate triglyceride-lowering effects on primary prevention of CHD. Important statistical properties must be taken into consideration in evaluating triglyceride as a risk factor for CHD. The large variability of triglyceride measurements and the correlation of triglyceride values with other lipid measures appears to result in the underestimation of the association between triglyceride and disease in multivariate analyses. Finally, individual genetic susceptibility may play an important role in the relation between plasma triglyceride levels and CHD. For example, risk of CHD clearly varies among the well-established familial forms of hypertriglyceridemia. A predominance of small, dense, LDL particles (LDL subclass pattern B) also appears to be a genetic trait associated with both increased risk of MI and increases in plasma triglyceride levels.

Relationship between plasma cholesterol and coronary artery disease in Asians

Cholesterol, high density lipoprotein (HDL) cholesterol and triglyceride concentrations were measured in 150 male survivors of first myocardial infarction and in 115 age and ethnic matched healthy controls. The total cholesterol concentration was higher in whites than in respective Asian groups and higher in patients than in controls (P less than 0.001). The ratio of cholesterol to HDL cholesterol was significantly higher in patients (P less than 0.001) and in both ethnic groups was a powerful independent predictor of cases. In Asians, the extent of coronary atheroma assessed by arteriography 2-12 weeks after infarction correlated independently with the total cholesterol concentration (P = 0.03). Thus, in Asian men, the lower level of total cholesterol compared to whites may be misleading. In Asian men the extent of atheroma correlated with the total cholesterol concentration and the relative risk of infarction increased with the ratio of total to HDL cholesterol. At a given level of cholesterol different ethnic groups may be at differing levels of cardiac risk and the cholesterol ratio may be a more appropriate means of inter-ethnic comparison.

High density lipoprotein cholesterol and triglycerides as markers of angiographically assessed coronary artery disease

Serum triglycerides, high density lipoprotein (HDL) cholesterol, and total cholesterol were measured in 698 patients examined by angiography. The ratio of HDL cholesterol to total cholesterol was significantly lower in patients with single, double, and triple vessel disease than in patients without disease. The serum concentration of triglyceride was significantly higher in patients with single, double, and triple vessel disease than in those without coronary artery disease. Similar proportion of patients with coronary artery disease and without had serum cholesterol concentrations of greater than or equal to 6.5 mmol/l, but total cholesterol was significantly higher in patients with single, double, and triple vessel disease than in those without. HDL cholesterol (less than 1.0 mmol/l), triglycerides (greater than 2.0 mmol/l), and the ratio of HDL cholesterol to total cholesterol (less than 0.20) were significantly better than total cholesterol as indicators of coronary risk.

Use of smokeless tobacco, cigarette smoking, and hypercholesterolemia

The primary purpose of this study was to determine the extent to which regular use of smokeless tobacco is associated with hypercholesterolemia (greater than or equal to 6.2 mmol/L) among 2,840 adult males. The confounding effects of age, education, physical fitness, body fatness, and other tobacco use were also examined. After adjustment, smokeless tobacco users were 2.5 times, heavy smokers were 2 times and mild/moderate smokers were 1.5 times more likely to have hypercholesterolemia than non-users of tobacco. Cigarette smokers did not differ significantly from users of smokeless tobacco regarding hypercholesterolemia. Users of smokeless tobacco were younger and less educated compared to non-users of tobacco, while smokers were less educated and less physically fit.

Triglycerides. Are they important?

The importance of lowering plasma cholesterol is well documented, but hypertriglyceridemia should not be ignored. Effective management requires proper measurement of plasma triglyceride levels and assessment of underlying causes. Conveniently, the same principles used in management of hypercholesterolemia can be applied to hypertriglyceridemia, and patients should be counseled regarding appropriate dietary measures. If these fail, medication may be necessary.

Post-heparin lipases, lipids and related hormones in men undergoing coronary arteriography to assess atherosclerosis

Post-heparin lipase activities were measured in normolipemic men with complaints suggestive of symptomatic coronary artery disease. A study group, who showed diffuse atherosclerotic narrowing of the coronary vessels, assessed by a quantitative computer-assisted analysis method, had a lowered hepatic lipase in comparison with a group with normal angiograms. Lipoprotein lipase was lower in the study group but well within the normal range and not statistically different. Some related hormones (cortisol, estradiol, testosterone and glucagon) were different in the two groups while others (insulin, human growth hormone, prolactin, thyroid hormones) were not. The results are discussed in view of the proposed role of hepatic lipase in the uptake of HDL-cholesterol by the liver.

Borderline low thyroid function and thyroid autoimmunity. Risk factors for coronary heart disease?

Assessments were made of 945 consecutive hospital patients with regard to a relation between borderline low thyroid function (recognised by a slightly raised thyroid stimulating hormone), thyroid autoimmunity, serum cholesterol, and coronary heart disease. Men and women with a thyroid autoimmunity, serum cholesterol, and coronary heart disease. Men and women with a thyroid stimulating hormone of 4.0 mU/l or over had a higher prevalence of coronary heart disease than did age-matched controls, and this difference was significant in women. The excess of coronary heart disease was not explained by an excess of other risk factors such as a high cholesterol, hypertension, smoking, and diabetes. Women with thyroid antibodies had a slightly higher prevalence of coronary heart disease despite the unexpected finding of a lower serum cholesterol. The data point to an association between borderline thyroid function and autoimmunity and coronary heart disease which is not mediated through a raised serum cholesterol.

Epidemiology as a guide to clinical decisions. The association between triglyceride and coronary heart disease

The hypothesis that triglyceride is a cause of coronary heart disease, although unconfirmed and never universally accepted, has nonetheless strongly influenced the practice of preventive medicine. We have examined the epidemiologic association between triglyceride and coronary heart disease to evaluate the validity of inferring that there is a causal relation between the two. Neither the evidence from published studies nor an analysis of data from the Western Collaborative Group Study provides strong support for the causal hypothesis. Information from other scientific disciplines is also meager, contrasting with the coherence of diverse evidence supporting the hypothesis that cholesterol is a cause of coronary heart disease. These arguments fall short of disproving the belief that lowering triglyceride will prevent coronary heart disease, especially since triglyceride and cholesterol are inextricably associated through mutual lipoprotein carriers. But we propose that the ethics of preventive medicine place the burden of proof on the proponents of intervention. We therefore recommend that widespread screening and treatment of healthy persons for hypertriglyceridemia be abandoned until more persuasive evidence becomes available.

Beta- and pre-beta-lipoproteins in coronary disease and hyperlipoproteinaemia

A very high percentage of male patients with proven coronary disease and/or raised lipid levels had a pre-beta-hyperlipoproteinaemia (class P [6] or Fredrickson [3] type IV) and relatively few had a beta-hyperlipoproteinaemia (class B or Fredrickson type IIA). Mixed hyperlipoproteinaemia was found in a large number of male patients but these again had predominantly raised triglyceride. More female patients over 40 years had beta-hyperlipoproteinaemia. Our retrospective study shows that raised triglyceride levels are more often found in patients with coronary disease than raised cholesterol levels.

Coronary artery disease in young Australian women

Over a 12-year period, from 1965 to 1977, 43 women under 46 years of age were documented with angiographic evidence of coronary atherosclerosis at St Vincent's Hospital, Sydney. Twenty-five of the women were able to be followed up at a mean interval of 31 months. This group of young women with coronary artery disease was compared with an age-matched control group of 660 "healthy" women drawn from the general population. Hyperlipidaemia was present in 72% of patients and in 13% of controls. Seventy-three percent of patients were regular cigarette smokers compared with 21% of controls. Only one patient out of 43 showed neither hyperlipikaemia, nor hypertension, nor smoked cigarettes, and multiple risk factors were commonly present. The level of high density or alpha-lipoprotein was significantly reduced in young women with coronary artery disease. These results highlight the presence of classical risk factors in these young women, as well as the importance of alpha-lipoproteins.