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

Fractional esterification rate of cholesterol and ratio of triglycerides to HDL-cholesterol are powerful predictors of positive findings on coronary angiography

BACKGROUND

We examined the predictive value of various clinical and biochemical markers for angiographically defined coronary artery disease (aCAD). Specifically, we assessed the value of the ratio of plasma triglyceride (TGs) to HDL-cholesterol (HDL-C) and the fractional esterification rate of cholesterol in plasma depleted of apolipoprotein B (apoB)-containing lipoproteins (FER(HDL)), a functional marker of HDL and LDL particle size.

METHODS

Patients (788 men and 320 women) undergoing coronary angiography were classified into groups with positive [aCAD(+)] and negative [aCAD(-)] findings. Patient age, body mass index, waist circumference, blood pressure (BP), medications, drinking, smoking, exercise habits, and plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-unesterified cholesterol, HDL-C, TGs, FER(HDL), apoB, log(TG/HDL-C), and TC/HDL-C were assessed. Lipids and apoproteins were measured by standard laboratory procedures; FER(HDL) was determined by a radioassay.

RESULTS

Members of the aCAD(+) group were older and had a higher incidence of smoking and diabetes than those in the aCAD(-) group. The aCAD(+) group also had higher TG, apoB, FER(HDL), and log(TG/HDL-C) and lower HDL-C values. aCAD(+) women had greater waist circumference and higher plasma TC and TC/HDL-C. aCAD(+) men, but not women, had higher plasma LDL-C. In the multivariate logistic model, the significant predictors of the presence of aCAD(+) were FER(HDL), age, smoking, and diabetes. If only laboratory tests were included in the multivariate logistic model, FER(HDL) appeared as the sole predictor of aCAD(+). Log(TG/HDL-C) was an independent predictor when FER(HDL) was omitted from multivariate analysis.

CONCLUSIONS

FER(HDL) was the best laboratory predictor of the presence of coronary atherosclerotic lesions.

Lipoprotein lipid response to the National Cholesterol Education Program step II diet by hypercholesterolemic and combined hyperlipidemic women and men

The beFIT study tested whether teaching the NCEP step II diet (< 30% of calories from total fat and < 7% from saturated fat) is an effective therapy in hypercholesterolemic women and men with or without elevated triglycerides after 6 months. Hypercholesterolemic subjects had two LDL cholesterol measurements above the age- and sex-specific 75th percentile, and combined hyperlipidemic subjects additionally had similarly elevated triglyceride. Subjects were randomized to receive dietary intervention (eight weekly classes) immediately or 6 months later. Follow-up visits were quarterly, with lipid measurements and 4-day food records. Subjects randomized to delayed intervention did not report diet changes or experience lipid changes; the immediate intervention group significantly reduced fat and cholesterol intake, resulting in significant LDL cholesterol lowering. Six months after diet instruction, 178 women and 231 men reported total and saturated fat intakes of approximately 25% and 7.5% kcal LDL cholesterol was significantly reduced in women (7.6% and 8.1%) and men (8.8% and 8.1%) with hypercholesterolemia and combined hyperlipidemia, respectively, but was not different by sex or lipid disorder. Candidates for drug therapy were reduced from between 27% and 37% to 20%. HDL cholesterol was significantly decreased in women (-6.4% and -4.7%) but not in men (-1.3% and -2.7%). The 6.4% reduction in hypercholesterolemic women was significantly different from that of men. The significance of the HDL cholesterol reduction in women is unknown. LDL cholesterol response was similar between women and men and between hypercholesterolemic and combined hyperlipidemic subjects. LDL cholesterol lowering by diet can significantly reduce the number of hyperlipidemic persons requiring drug therapy.

Dose-response relationships of serum lipid measurements with the extent of coronary stenosis. Strong, independent, and comprehensive. ECAT Angina Pectoris Study Group

Serum lipids, lipoproteins, and more recently apolipoproteins and lipoprotein(a) [Lp(a)] have been shown to be independent risk factors for coronary vessel disease and its prognosis. However, the relationships between serum lipid levels and the extent of coronary artery disease (CAD) have not been consistently shown. Twenty-five hundred male and female patients with suspected angina pectoris were recruited from 18 European medical centers. The independent relations of total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, apo A-I and B, and Lp(a) with the presence and extent of CAD, as assessed by coronary angiography, were investigated. All of the lipid measures showed strong relations P < .0001) with the presence of CAD, defined by the existence of at least one > or = 50% coronary vessel stenosis. Total cholesterol, LDL cholesterol, apo B, triglycerides, and Lp(a) were substantially higher and HDL cholesterol and apo A-I lower in patients with CAD. The odds ratio of CAD, in the high-risk tertile of each lipid's distribution compared with the low-risk tertile, was in the range 1.5 to 2.3. Each of total cholesterol (or LDL cholesterol or apo B), HDL cholesterol (or apo A), and Lp(a) had an independent effect in predicting the presence of CAD. In addition, all lipids showed a strong association (P = .0006 for triglycerides, P < .0001 otherwise) with the extent of CAD as defined by the number of stenosed coronary vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Lecithin-cholesterol acryltransferase activity in patients with coronary artery disease examined by coronary angiography

This study grew out of observations of certain lecithin:cholesterol acyltransferase (LCAT) abnormalities in patients with atherosclerosis. We studied the interrelationships among LCAT, and total cholesterol, free and esterified cholesterol, cholesterol in individual lipoprotein fractions, triglycerides, phospholipids, free fatty acids, L-lactates in 90 angiographically examined patients with coronary artery disease and 30 control subjects without clinical manifestations of coronary artery disease. Results of the study showed LCAT activity to be significantly decreased (P < 0.05) in patients with single-, double-, or triple-vessel disease than in disease-free subjects. LCAT was also found to follow the stage of coronary artery disease in angiographically examined patients. Decreased LCAT activity was accompanied by lower high-density lipoprotein cholesterol, elevated ratio of unesterified to esterified cholesterol, and increased levels of L-lactates, free fatty acids, and low-density lipoprotein cholesterol. Total cholesterol and triglycerides were within or slightly above the normal limits. The results show LCAT to be a significantly better indicator of the risk of coronary artery disease than either total cholesterol or triglycerides.

Postprandial plasma lipoprotein changes in relation to apolipoprotein E phenotypes and low density lipoprotein size in men with and without coronary artery disease

Postprandial lipoprotein metabolism may play a role in the etiology of premature coronary artery disease (CAD). To determine whether apolipoprotein E (apo E) polymorphism and the size of low density lipoprotein (LDL) influence postprandial lipemia we studied 39 healthy men and 35 men with CAD. Venous blood samples were obtained before an oral fat load and 3, 5 and 7 h thereafter. Total cholesterol and high density lipoprotein (HDL) cholesterol concentrations did not change in either group during the fat load, but triglycerides increased more markedly in CAD patients compared with controls independently of apo E phenotypes. There was a positive correlation between the size of LDL and the concentration of HDL cholesterol (r = 0.541, P < 0.001); conversely, an inverse correlation was observed between LDL size and the level of fasting triglycerides (r = -0.582; P < 0.001). The patients with CAD had significantly smaller LDL particles (25.89 +/- 0.56 nm) than in controls (26.21 +/- 0.63 nm) (P < 0.05). The increase in triglyceride levels during the fat load was highest in CAD patients with a small size of LDL particles (< 25.5 nm) and lowest in controls with large LDL (> 25.5 nm). Our results suggest that the magnitude of the triglyceride response is a better indicator of CAD risk than the fasting triglyceride concentration. The best model in our logistic regression analysis selected as significant risk factors the change of triglyceride concentration from the baseline at 5 h after a fat meal and HDL cholesterol. This model classified 83% of the subjects correctly.

Apolipoproteins C-II and C-III in peripheral arterial disease

Apolipoprotein (apo) C-II and apo C-III serum concentrations were investigated in 119 normotriglyceridemic male subjects with peripheral arterial disease (PAD) or coronary heart disease (CHD) or without clinical manifestations of atherosclerotic disease. All subjects included in the study had similar blood levels of total cholesterol (< 400 mg/dL). High-density lipoproteins cholesterol (HDL-C) subfractions and apo A-I serum levels were significantly lower in CHD patients, as were apo A-I/apo B and HDL-cholesterol/total cholesterol ratios. Apo C-II and apo C-III showed similar serum concentrations in all three groups of subjects, but apo C-II/apo C-III ratio was significantly lower in PAD patients as compared with that in CHD patients and control subjects. This study confirms that PAD may be associated with a particular lipoprotein derangement that primarily involves very low-density lipoprotein catabolism.

Pharmacological control of hypertriglyceridemia

Hypertriglyceridemia has been recently recognized as a vascular risk factor, based on both clinical and experimental findings. Epidemiological studies clearly showed that elevated plasma triglycerides in subjects with low high-density lipoprotein (HDL) cholesterol (<35 mg/dl) and/or a low-density lipoprotein (LDL)/HDL cholesterol ratio > 5 are associated with an elevated risk for coronary heart disease (CHD), while intervention studies indicate that triglyceride lowering with drugs may lead to a significant CHD reduction. Elevated blood triglycerides are associated with major alterations in the structure/function of plasma lipoproteins, which become more atherogenic, and with abnormalities in the clotting system, which may predispose to coronary thrombosis. New criteria for the classification of hypertriglyceridemias and a stepwise approach to the management of patients with elevated plasma triglycerides have been recently developed. Nonpharmacological interventions, i.e., weight reduction, alcohol and smoking cessation, and physical exercise, are the first-line actions to control hypertriglyceridemia. Drug therapy should be considered when the nonpharmacological approaches are ineffective or inadequate. Fibric acid derivatives and nicotinic acid (and its derivatives) are the drugs of choice when treating hypertriglyceridemic patients; n-3 fatty acids (fish oil) and metformin (especially in diabetic patients) represent additional therapeutic agents.

Plasma lipid concentrations and subsequent coronary occlusion after a first myocardial infarction. The POSCH Group

This study correlated plasma lipid values with angiographic evidence of progression to complete coronary occlusion. Baseline triglycerides (TGs), total cholesterol (Chol), high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, and HDL/LDL and HDL/Chol ratios were compared with coronary angiograms taken at baseline, 3 and 5 years in a prospective angiographic study. Results were from part of the multicenter trial of plasma lipid reduction in patients after a single myocardial infarction (POSCH). Comparison of patient's baseline lipids in the absence or presence of a new total coronary occlusion at 3 years showed a significant difference (p = 0.01) in TGs of 197 +/- 147 versus 250 +/- 162 mg/dl (p = 0.02) and VLDL of 30 +/- 23 (n = 284) versus 40 +/- 30 (n = 49) mg/dl. Stratification by the mean HDL/Chol ratio (16%) demonstrated that baseline TG levels were significantly increased in patients with a new coronary occlusion by 3 years despite a higher HDL/Chol ratio. When measured at the 3-year visit, plasma TG (176 +/- 91 versus 212 +/- 146 mg/dl; p = 0.02) and VLDL (28 +/- 18 versus 35 +/- 29 mg/dl; p = 0.04) were significantly elevated in the presence of a new 3-year coronary occlusion. Stratification by the mean HDL/Chol ratio (16%) demonstrated that 3-year TG levels increased significantly in patients with a new 3-year coronary occlusion despite a higher HDL/Chol ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of angiographically detected coronary artery disease with low levels of high-density lipoprotein cholesterol and systemic hypertension

The prevalence of risk factors for atherosclerosis in 488 consecutive patients undergoing cardiac catheterization for the investigation of chest pain was compared with that in 868 subjects from a population sample. The presence and severity of angiographic coronary artery disease (CAD) (defined as mean diameter stenosis > 50%), total and high-density lipoprotein (HDL) cholesterol, triglycerides, history of systemic hypertension, smoking, diabetes mellitus, family history and drug therapy were assessed. Low HDL cholesterol (< 0.9 mmol/liter [35 mg/dl]) was more prevalent in patients with CAD than in the population sample in both men (44% [95% confidence interval 38 to 48] vs 21% [12 to 28]; p < 0.01) and women (12% [9 to 15] vs 1% [0 to 3]; p < 0.01). There were no differences in total cholesterol levels between these 2 groups. Total:HDL cholesterol ratios were significantly greater in patients with CAD. History of systemic hypertension was more prevalent in both men and women with CAD than in the population sample (47% [37 to 57] vs 20% [16 to 25] for men, and 31% [26 to 36] vs 21% [17 to 26] for women; p < 0.01). The prevalence of other risk factors was not significantly different between the 2 groups. In patients with CAD, the severity of disease was inversely correlated with levels of HDL cholesterol in both men and women (p < 0.01), and positively correlated with total cholesterol in men aged < 55 years (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Increased triglyceride levels in shift workers

PURPOSE

To assess an independent relationship between shift work and serum lipid levels.

DESIGN

Cross-sectional survey.

SETTING

Two plants of northern France: a chemical one and a nuclear power station.

PARTICIPANTS

All the shift workers of the chemical plant and of one part of the nuclear station. One hundred nine persons were selected, 25 were excluded or absent during the study, and 11 refused to participate. Day workers matched with shift workers according to age, educational level, birthplace, and occupational physical activity level served as controls; 109 were selected, 26 were excluded or absent, and 10 refused to participate.

MAIN OUTCOME MEASURES

Fasting venous plasma concentration of total cholesterol, triglyceride, and high-density lipoprotein (HDL) cholesterol; dietary intake assessed by a 3-day record, smoking habits, and body mass index (BMI).

RESULTS

Shift workers had significantly higher levels of serum triglyceride (1.26 versus 1.03 mmol/L, p = 0.01). Cholesterol and HDL cholesterol levels were similar for the two groups. There was no difference in energy and nutrient intake, but day workers had a higher alcohol intake (15.64 g/d versus 9.3 g/d, p = 0.03). Multivariate analysis conducted with triglycerides as dependent variable and shift work, BMI, smoking, age, leisure time physical activity level, energy intake, and alcohol intake as independent variables confirmed that shift work has a significant explanatory power for triglyceride levels (beta = 0.134, p = 0.0005).

CONCLUSION

This study confirms that shift work is associated with an increase of triglyceride levels independent of dietary intake. We did not find any influence of shift work on cholesterol and HDL cholesterol. Despite this latter fact, our findings are to be considered in the explanation of coronary risk among shift workers. Further studies are needed to elucidate the mechanism of this relative hypertriglyceridemia: stress induced by shift work or diurnal rhythm disturbances.

Screening persons aged 65 and older for coronary heart disease risk factors

Because of limited clinical investigations addressing the effectiveness of intervention to reduce known risk factors, it is difficult for primary care physicians to decide on which coronary heart disease risk factors to continue to screen for among older patients. The recently published report of the United States Preventive Services Task Force, using explicit screening criteria, has recommended that several risk factors be investigated for use among older adults. Recent longitudinal studies have found that a number of risk factors persist with advancing age-hypertension, left ventricular hypertrophy, impaired glucose metabolism, elevated cholesterol levels, obesity, smoking, physical inactivity, decline in vital capacity, and increased heart rate. Screening to identify many of these risks and treatment and counseling to modify them appear to improve survival. Evidence is less clear that diabetes mellitus and elevated cholesterol levels have the same significance for men and women as they age. Left ventricular hypertrophy and diabetes seem particularly important as risk factors for older women, whereas a high heart rate may be a greater risk for men.

Ethnic immunity to coronary heart disease?

Dietary fat intake is often regarded as a major determinant of coronary heart disease (CHD) rate and it has been deemed unnecessary to invoke racial or other factors to explain the differences in CHD rates among different ethnic groups. Despite a high prevalence of CHD risk factors such as hypertension, obesity, and smoking, CHD remains a rarity in westernized black Africans. Cord blood total cholesterol (TC), low density lipoprotein cholesterol (LDLC) and apolipoprotein B (apo B) levels were measured and found to be respectively 12.1%, 18.3% and 22.4% lower in black neonates when compared to white neonates. These differences were again studied in a group of young black African males and a comparable group of age-matched whites who had been exposed to the same environment and western diet for at least 2 years. Although the body mass indices and serum albumin concentrations in the adult males were not significantly different, serum levels of TC, LDLC and apo B were 10.7%, 18.7% and 39.7% lower in the blacks, respectively. Furthermore, high density lipoprotein cholesterol (HDLC) and Apolipoprotein AI were 20.2% and 9.5% higher, homocysteine 45.6% lower and coagulation factor VII 26.6% lower in the adult black Africans. It is concluded that blacks are biochemically less responsive to an atherogenic diet than whites and these differences are already present at birth.