Serum lipoproteins and coronary heart disease

It is necessary to examine lipid abnormalities at a macromolecular level, with emphasis on the transport lipoproteins rather than on cholesterol and triglyceride values alone. Methods for determining serum lipoproteins, which can be adapted for a small laboratory, are now available and are recommended for general clinical use. It is becoming increasingly apparent that the process of atherosclerosis has a long natural history that begins in childhood, and that it is now possible to study children for potential risk.     

Accumulation of apoE-enriched triglyceride-rich lipoproteins in patients with coronary artery disease

Triglycerides (TGs) are vehicled by multiple particles with different abilities to promote atherosclerosis. Among plasma TG-rich lipoproteins (TRLs), subspecies may or may not contain apolipoprotein E (apoE) molecules: in this study, we evaluated the relative contribution of apoE-rich and apoE-poor TRLs to coronary atherosclerosis. We selected a group of males with premature coronary artery disease (CAD) without any of the classical nonlipid risk factors and/or high plasma lipid levels and evaluated the plasma concentration of TRL subspecies in comparison with healthy controls. Patients with CAD and controls had total cholesterol and TG levels within the normal range (despite slightly, even if significantly, higher TG levels in patients with CAD) and low-density lipoprotein cholesterol levels near optimal values. Nevertheless, patients with CAD had significantly lower high-density lipoprotein cholesterol, smaller low-density lipoprotein peak particle size, and a reduced HDL2b subfraction than controls. In addition, we observed higher concentrations of total TRL in patients with CAD together with a selective increase in apoE-rich particles. All these data were confirmed after correction for TG levels. We also investigated which parameters were associated with the spread of coronary atherosclerosis. Subjects with a single-vessel disease had selectively lower levels of apoE-rich fractions than patients with a multivessel disease. This was confirmed by multivariate analysis. Patients with a premature CAD free of nonlipid conventional risk factors, despite not having elevated lipid levels, show several lipoprotein abnormalities. Besides known atherogenic alterations, the accumulation of apoE-rich TRL subfractions may represent an additive factor that can potentially promote and initiate the atherosclerotic process.     

Plant-based diets and control of lipids and coronary heart disease risk

Coronary heart disease (CHD) is a major cause of death worldwide. Dietary factors have an important role in influencing the outcome of this disease. Dietary guidelines around the world now recommend increased consumption of plant foods for the prevention of CHD. Epidemiologic and human intervention studies have documented an inverse relationship between the consumption of plant-based diets and deaths attributed to heart disease. Plant foods contain many beneficial compounds that, by acting through multiple mechanisms, provide protection against the disease. American and Canadian recommendations for the daily intake of fruits and vegetables provide a sound basis for a healthy diet and the prevention of CHD.     

The effects of low-fat,high-carbohydrate diets on plasma lipoproteins,weight loss,and heart disease risk reduction

Although there is consensus about restriction of dietary saturated and trans fatty acids, cholesterol, and sugars, there is debate about what the optimal total fat and carbohydrate content of the diet should be for weight loss and coronary heart disease (CHD) risk reduction. The overall evidence that dietary composition plays an important role in determining caloric intake is limited. Three recent randomized trials have indicated that lowcarbohydrate diets are more effective in promoting weight loss in overweight and obese subjects over 4 to 6 months, but not over 1 year. In our own randomized trial no such differences were noted, and compliance with extreme diets was limited. Moreover little attempt has been made to control for the type of carbohydrate used in the low-fat, high-carbohydrate arms of these trials. Available evidence suggests that restriction of sugars and carbohydrates having a high glycemic index would be preferable to total carbohydrate restriction, and that an increased intake of fiber and essential fats (especially omega-3 fatty acids) is also important for overall heart disease risk reduction.     

Lipids, lipoproteins, and coronary heart disease: Implications for antihypertensive therapy

There is now considerable evidence that treatment of abnormalities of lipids and lipoproteins reduces the incidence of coronary heart disease (CHD). Treatment of hypertension, another major cardiovascular risk factor, has not been shown to have the same impact on CHD. Possible explanations for this are that cardiovascular risk factors may occur in combination in an individual or that therapy for hypertension has adversely affected one or several of the other risk factors for CHD, thereby effuetting the benefit gained by lowering blood pressure.This article reviews the relationship between lipids, lipoproteins, and coronary heart disease, and the impact of cholesterol lowering on CHD. The evidence that antihypertensive drugs are associated with lipid and lipoprotein abnormalities is introduced by a critical appraisal of the several studies for such evidence. Implications for the treatment of the hypertensive patient are discussed.     

Smoking, lipoproteins and coronary heart disease risk: Data from the Munster Heart Study (PROCAM)

Aims The mechanism of the increase in coronary heart disease riskassociated with smoking is unclear, but may partly be due tosmoking-related changes in intermediate risk factors such aslipid levels, fibrinogen and blood pressure. We therefore examinedthe distribution of these variables among smokers and non-smokersin the Münster Heart Study. Methods 20696 men, aged 41·7±2·7 years (mean±SD)and 10212 women, aged 37·0±2·6 years, wereenrolled between 1978 and 1995. Thirty-two percent of womenand 36% of men smoked. Compared to non-smokers, mean levelsof low density lipoprotein cholesterol, total cholesterol, triglyceridesand fibrinogen were increased, respectively, by 1·4%,0·9%, 15% and 12·1% in male and by 2·0%,5·5%, 12% and 3·4% in female smokers. Mean highdensity lipoprotein cholesterol levels, body mass index andblood pressure were reduced, respectively, by 6·4%, 3·8%,and 2% in male, and by 6·7% 1·2% and 2% in femalesmokers. In the subgroup of 4639 men aged 40 to 65 with 8 yearsof follow-up, the coronary event rate (definite myocardial infarction,sudden cardiac death) in cigarette smokers was more than twicethat of non-smokers with otherwise identical risk factors. Conclusion In the Münster Heart Study, smoking was associated withadverse changes in lipids (of greater magnitude in women), andfibrinogen (of greater magnitude in men). However, these changesexplained only a small part of the smoking-related increasein coronary heart disease risk.The European Society of Cardiology     

Technology, coronary heart disease and its risk factors

Cardiovascular diseases, predominantly coronary heart disease (CHD), are the leading public health problem in industrialized countries. They are associated with a number of variables, such as blood pressure (BP), smoking serum level of lipids, obesity etc for which technological progress is also incriminated. This relation has not been evaluated in Greece. This country is a developing one with different status of technology in different areas. In Athens it is almost similar to Western societies, but in rural areas it varies. This paper reports on morbidity of CHD and its risk factors (RF) in Greek populations with different technology.     

Lipids, lipoproteins, fibrinogen and fibrinolytic activity in angiographically assessed coronary heart disease

Plasma lipids, lipoproteins, fibrinogen and fibrinolytic activity (FA) were measured in 202 consecutive patients undergoing coronary angiography. Twenty-one patients, 13 men and 8 women with a mean age of 52.8 years and 56.7 years respectively, were found to be angiographically free of coronary artery disease (CAD) and served as the principal control group. Since this group contained a disproportionate number of subjects with risk factors such as family history, hypertension and smoking, a second control group of clinically healthy subjects selected for age was also tested. Their laboratory results were not used in the statistical calculations. The group with angiographic CAD consisted of 130 men (mean age 57.6 years) and 51 women (mean age 61.5 years). Abnormal angiograms were graded according to the number of major vessels with more than 50% stenosis involved. The laboratory variables which were significantly (p less than .01-.001) associated with the presence of CAD were: High density lipoprotein (HDL) when determined by polyacrylamide gel electrophoresis (PAGE) and expressed as a percentage of total lipoproteins rather than concentration, presence of Intermediate Density Lipoprotein (IDL), percent of Very Low Density Lipoprotein (VLDL), fibrinogen concentration and FA. The HDL2 subfraction was significantly inversely correlated only in women. The total plasma cholesterol was normal and virtually identical in both groups. Within the CAD group, only two of the laboratory results were significantly correlated with the extent of disease. By univariate analysis, the FA showed the closest association with the score for severity of CAD (p less than .001) followed by the presence of IDL (p less than .01). In conclusion, lipoprotein analysis by a method which measures not only HDL, but also LDL, VLDL and IDL, together with the determination of fibrinogen and FA provides information useful in the identification of individuals at risk for CAD.     

High density lipoproteins, genetic polymorphism for apo A-I and coronary artery disease

HDL cholesterol and apolipoprotein A-I are associated with the development of coronary artery-disease (CAD). The presence of a PstI site polymorphism adjacent to the gene encoding apo A-I (known as P₂) has also been shown to be associated with CAD but this relationship is controversial. A case control study was conducted in an Australian population to re-examine whether the rare P₂ allele is associated with CAD. Data were derived from 159 cases of angiographically confirmed CAD and 99 healthy controls. The proportion of CAD cases carrying the P₂ allele did not differ significantly from controls (11% versus 9%). In a multiple logistic regression model controlling for the effects of age, country of birth, hypertension and hypotensive drugs, body mass index and lipid variables, the P₂ allele failed to predict significantly the presence of CAD (odds ratio 1.83; 95% confidence interval 0.65–5.19).     

Women and coronary heart disease risk factors

The prevalence of cardiovascular risk factors among women is high and cardiovascular risk factors often occur in clusters. Strong relationships between exposure to cigarette smoke, physical inactivity, hypertension, and abnormal levels of lipoproteins and homocysteine and subsequent coronary heart disease (CHD) in women are evident from many studies, while the impact of menopause, psychosocial factors, and inflammatory markers is less clear and requires further study. Observational studies document that smoking cessation reduces CHD risk among persons with and without existing CHD, and that moderate levels of physical activity are associated with lower CHD risk. Clinical trials over the last decade have convincingly shown that treatment of hypertension and dyslipidemia reduces CHD risk in both genders, but many women (and men) with hypertension and dyslipidemia remain either untreated or under-treated.