Metabolic syndrome and ischemic heart disease in elderly men and women

Associations between metabolic syndrome components and prevalent ischemic heart disease (IHD) were investigated in a cross-sectional, community-based study of elderly men (n = 1,015) and women (n = 1,259) in Rancho Bernardo, California, in 1984-1987. In both sexes, there were significant positive associations between IHD defined by resting electrocardiogram criteria and age, systolic blood pressure, fasting and postchallenge hyperglycemia, total cholesterol/high density lipoprotein cholesterol (HDL cholesterol) ratio, and triglycerides and an inverse significant association with HDL cholesterol. High collinearity and interactions between serum insulin and metabolic syndrome variables were accounted for by uncorrelated principal components identified by factor analysis. In both men and women, three uncorrelated principal components were identified, representing a central metabolic factor (body mass index, fasting and 2-hour serum insulin, high serum triglycerides, and low HDL cholesterol), a glucose factor, and a blood pressure factor. In a multivariate model with age and sex, all three factors were significantly associated with IHD by electrocardiogram criteria; central metabolic factor (odds ratio (OR) = 1.6, p = 0.001), glucose factor (OR = 1.4, p < 0.001), blood pressure factor (OR = 1.2, p = 0.005), age (10 years) (OR = 1.8, p < 0.001), and female sex (OR = 0.5, p < 0.02). Similar results were obtained in analyses using clinically manifest IHD as the outcome. These results support the thesis that the metabolic syndrome exerts effects through different risk factors by different mechanisms.     

Plasma fluorescent oxidation products: independent predictors of coronary heart disease in men

Fluorescent oxidation products in plasma are stable with routine blood collection methods and reflect oxidation in food, animals, and in vitro. Whether plasma fluorescent oxidation products predict future coronary heart disease has not been established. Among US men without cardiovascular disease who provided blood specimens in 1994 in the Health Professionals Follow-up Study, the authors confirmed 266 incident nonfatal myocardial infarction or fatal coronary heart disease endpoints during 6 years of follow-up. Using a nested case-control design, they measured baseline levels of fluorescent oxidation products. Each case was matched with two controls according to age, smoking status, and time of blood draw. The relative risk of coronary heart disease between extreme quintiles was 1.83 (95% confidence interval: 1.07, 3.13; p for trend = 0.005) in the multivariate analysis controlling for other cardiovascular risk factors and traditional lipid markers. Further adjustment for C-reactive protein and glycated hemoglobin A(1c) did not materially attenuate this association. The multivariate-adjusted relative risk between extreme quintiles was 3.36 (95% confidence interval: 1.33, 8.48; p for trend = 0.005) when the analysis was restricted to men who had fasted for more than 10 hours before blood draw. The authors found that plasma fluorescent oxidation products significantly and independently predicted coronary heart disease incidence among men without previous cardiovascular events.     

Family history of stroke as an independent predictor of ischemic heart disease in men and stroke in women

The major known cardiovascular risk factors, age, cholesterol, blood pressure, cigarette smoking, and diabetes and family history of heart attack, explain only a proportion of cardiovascular disease. In a study of 1,491 men and 1,924 women aged 50-79 years in an upper middle-class Caucasian population in Rancho Bernardo, southern California, who were free of known cardiovascular disease at baseline in 1972-1974 and who were followed for an average of nine years, family history of stroke in any first-degree relative was an independent predictor of ischemic heart disease mortality in men 50-64 years of age (relative risk = 3.3, p less than 0.05) and of stroke mortality in women 50-79 years of age (relative risk = 2.3, p less than 0.05) after controlling for all the above risk factors. In contrast, family history of stroke was not predictive of stroke mortality in men or of ischemic heart disease mortality in women. These results suggest that family history of stroke may be used as a marker for high-risk subjects and to identify and investigate other major genetic or environmental determinants for cardiovascular disease, particularly sex differences.     

Lipoproteins, nutrition, and heart disease

This article reviews the current status of our knowledge of lipoproteins, nutrition, and coronary heart disease (CHD). Special emphasis is placed on CHD risk assessment, dietary intervention studies, diet-gene interactions, and current dietary guidelines and the contributions of my laboratory to these areas. CHD remains a major cause of death and disability, and risk factors include age, sex, hypertension, smoking, diabetes, elevated serum LDL cholesterol, and low HDL cholesterol. Emerging independent risk factors include elevated serum concentrations of lipoprotein(a), remnant lipoproteins, and homocysteine. The cornerstone of CHD prevention is lifestyle modification. Dietary intervention studies support the concepts that restricting saturated fat and cholesterol and increasing the intake of essential fatty acids, especially n - 3 fatty acids, reduces CHD risk. The variability in LDL-cholesterol response to diet is large, related in part to APOE and APOA4 genotype. The use of antioxidants in intervention studies has not been shown to reduce CHD risk. Compliance with dietary recommendations remains a major problem, and directly altering the food supply may be the most effective way to ensure compliance. The available data indicate that the recommendation to use fats, oils, and sugars sparingly for CHD prevention should be modified to a recommendation to use animal, dairy, and hydrogenated fats; tropical oils; egg yolks; and sugars sparingly and to increase the use of vegetables, fruit, and whole grains.     

Body mass index and incident ischemic heart disease in South Korean men and women

Asian populations have a higher body fat percentage for a given body mass index (BMI) than Caucasians. However, little information is available on the association of BMI with ischemic heart disease (IHD) incidence in Asians at low BMI levels. The authors prospectively evaluated the association of BMI (weight (kg)/height m2) with IHD incidence over 9 years of follow-up (1993-2001) among 133,740 South Korean adults (89,050 men, 44,690 women) who participated in the 1990 and 1992 examinations of the Korea Medical Insurance Corporation Study. Average BMI at baseline was 23.4 (standard deviation, 2.3) in men and 22.3 (standard deviation, 2.3) in women. After multivariate adjustment, there was a 14% (95% confidence interval: 12, 16) increased risk of incident IHD per unit of increase in BMI. This trend was also observed within the range considered normal by Western standards, and a BMI of 24-<25 was associated with an IHD hazard ratio of 2.01 (95% confidence interval: 1.32, 3.05) in comparison with a BMI of 18-<19. The association of BMI with IHD in this cohort of relatively young South Korean men and women was progressive over the range of BMI values, with no threshold of change in risk and no indication of a U-shaped relation at low BMI levels.     

Toenail nicotine levels as predictors of coronary heart disease among women

The authors assess the ability of toenail nicotine levels as a biomarker to predict incident coronary heart disease (CHD). A nested case-control study was carried out among 62,641 women aged 36-61 years in the Nurses' Health Study cohort who provided toenail clippings in 1982. Between 1984 and 1998, 905 incident CHD cases were diagnosed and matched with two controls by age and date of toenail collection. Using multivariate logistic regression analyses, the authors found a statistically significant dose-response association between increasing toenail nicotine levels and risk of CHD (p(trend) < 0.0001); women in the highest quintile had a relative risk of 3.44 (95% confidence interval (CI): 2.56, 4.62) compared with women in the lowest quintile. With each increase in the log-transformed unit of continuous toenail nicotine levels, there was a 42% increase in the risk of CHD (relative risk = 1.42, 95% CI: 1.33, 1.52). The association remained significant when the number of cigarettes smoked and passive smoking were included as covariates (relative risk = 1.12, 95% CI: 1.01, 1.24). In conclusion, toenail nicotine levels are predictive of CHD among women independent of other risk factors and remained significant even after adjustment for history of cigarette smoking.     

Lipid and lipoprotein predictors of coronary heart disease in elderly men in the Honolulu Heart Program.

Data from the baseline and follow-up examinations of the Honolulu Heart Program (HHP) cohort of 8006 men of Japanese ancestry were used to examine several questions concerning the predictive role of lipids and lipoproteins for incident CHD. For the question "Do serum cholesterol levels measured in middle age predict incident CHD in elderly men 65 years old or older?" the answer was clearly yes. Multivariate relative risks and attributable risks for early and late onset of CHD were similar and statistically significant. For the question "Do serum cholesterol levels measured in the elderly predict subsequent CHD?" the answer again was clearly yes. Multivariate relative risks for elderly men were similar to those for middle-aged men, and attributable risks were consistently higher for elderly men. For the question "Do other lipid or lipoprotein levels measured in the elderly predict incident CHD better than serum cholesterol level?" the answer was no. Multivariate relative risks for low-density-lipoprotein (LDL) and non-high-density-lipoprotein cholesterol were similar to those for total cholesterol. HDL cholesterol was protective for incident CHD, but the patterns were not significant for the elderly. Serum triglyceride level was not a significant predictor of CHD for the elderly. The conclusion was that no matter at what age serum cholesterol was measured, it predicted subsequent CHD in the elderly men in this cohort.     

Serum lipids, lipoproteins, and apolipoproteins and the excessive occurrence of coronary heart disease in non-insulin-dependent diabetic patients

Serum lipids, lipoproteins, and major apolipoproteins and their association with previous myocardial infarction were studied in patients with non-insulin-dependent diabetes mellitus (NIDDM) and nondiabetic subjects in East and West Finland in 1982-1984. NIDDM patients had higher age-adjusted serum triglyceride and apolipoprotein B levels and a higher apolipoprotein B/apolipoprotein A-I ratio, lower serum high density lipoprotein (HDL) cholesterol and apolipoprotein A-1 levels, and a lower HDL cholesterol/apolipoprotein A-1 ratio than nondiabetic subjects. With a few exceptions, these differences persisted after adjustment for body mass index, alcohol intake, physical activity, smoking, and hypertension, which suggests that the atherogenic serum lipoprotein pattern in NIDDM is an inherent feature of the disease. In general, the association of serum lipids, lipoproteins, and apolipoproteins with myocardial infarction was similar in nondiabetic subjects and NIDDM patients, although it was somewhat stronger in the diabetic subjects. A low serum HDL cholesterol/apolipoprotein A-1 ratio, which was closely linked to high serum triglyceride level, seemed to be more consistently related to myocardial infarction in NIDDM patients than in nondiabetic subjects. Serum lipids, lipoproteins, and apolipoproteins, either separately or in various combinations, could only to a small extent explain the higher prevalence of myocardial infarction in diabetic subjects compared with nondiabetic subjects when tested in multivariate analysis with other cardiovascular risk factors as background variables. The association between serum lipoproteins and myocardial infarction was largely similar in East and West Finland, two areas that differ markedly with respect to the occurrence of coronary heart disease.     

Social networks as predictors of ischemic heart disease, cancer, stroke and hypertension: incidence, survival and mortality.

Three social network measures were obtained from a randomly sampled cohort of 2603 HMO members in 1970-71. Mortality and first incidence of ischemic heart disease, cancer, stroke, and hypertension were assessed over the next 15 years. Outcome data were adjusted for age, sex, smoking, SES, and baseline health status. Persons with histories of a given morbidity at or prior to baseline were excluded from the analyses of that morbidity. Social network measures, particularly network scope (a measure of the number of different domains in which a person has social contacts), were powerful predictors of 15-year mortality hazard, but weak predictors of incident disease. Only network scope predicted IHD incidence, and none of the other morbidities was predicted by the social network measures. However, social network measures were strong predictors of both cause-specific and all-cause mortality among persons who had incident cases of IHD, cancer, and stroke. These data suggest that social networks may be more effective in supporting recovery after illness has occurred than in preventing the incidence of new disease.     

Myocardial tissue concentrations of magnesium and potassium in men dying suddenly from ischemic heart disease.

Optimum tissue levels of magnesium and potassium ions are essential to the structure and function of the myocardium. We hypothesized that an inapparent deficiency of one or both of these elements might contribute to sudden cardiac death in a susceptible person, and in this study investigated levels of these elements in the myocardium of men experiencing sudden death to determine if there was such an association. Subjects dying suddenly with ischemic heart disease had significantly lower levels of myocardial tissue magnesium and potassium than the controls (men dying of acute trauma). The four lowest potassium values were obtained for the only men in the group with a history of angina (P less than 0.0005). Three of the men with angina also had the lowest tissue magnesium levels (P less than 0.005). The intriguing finding gives support to the hypothesis.     

Gender and ischemic heart disease

Physiological and pathological processes differ in men and women, depending on factors such as sex and sociological and anthropological characteristics. However, many diseases are still approached from a masculine point of view. In this respect, ischemic heart disease is one of the diseases that most clearly reflects biological differences and social inequalities. In women, the disease presents at a more advanced age, and presentation is frequently atypical with a higher prevalence of comorbidities and greater severity. Consequently, treatment and outcome differ from those in men. Additionally, women differ in their knowledge, and beliefs regarding ischemic heart disease, as well as in their attitudes at symptom onset. Therefore, clinical practice should place significant emphasis on all these aspects in order to avoid inequalities between men and women in the correct diagnosis, treatment, prevention, and rehabilitation of ischemic heart disease.     

Young adult cholesterol as a predictor of familial ischemic heart disease

Family history for ischemic heart disease (IHD) was quantified from 229 questionnaires returned by the parents of young adults who had their total serum cholesterol levels determined as seventh graders in 1972-1973 and again 9 years later. The participants were divided into low- or high-cholesterol groups using quintiles. There were nonsignificant trends for higher prevalence of IHD in the families of individuals, principally the male participants, with persistently high total serum cholesterol levels; an excess of IHD in families of young adults with reduced high-density lipoprotein cholesterol (HDL); and a deficit of IHD in families of high-HDL participants. There was a significant interaction in family history scores between HDL and total cholesterol, such that there was an excess of IHD prevalence in families of individuals with high total cholesterol and low HDL levels, and significantly lower IHD prevalence in families of young adults with high total cholesterol and high HDL levels. Among individuals with low total cholesterol, lower family history scores were found in those with lower HDL levels.     

Welding and ischemic heart disease

Metal welding and cutting are associated with inhalation of gases and respirable particles. The purpose of this study was to compare the mortality of male welders with that of all gainfully employed men in Sweden regarding ischemic heart disease (IHD). Male welders and gas cutters were identified in the Swedish National Censuses of 1970 and 1990. Two cohorts were established and followed until the end of 1995. The IHD mortality among the welders was compared with that of all gainfully employed men. An increased mortality due to IHD was observed among welders identified in the 1990 Census, SMR = 1.35, 95% confidence limits 1.1-1.6. The observed increased mortality due to IHD was unlikely to be explained by different smoking habits. A general hypothesis linking inhalation of particles to the occurrence of IHD via an inflammatory process is discussed.     

Social inequalities in ischemic heart disease and cerebrovascular disease mortality in men in Spain and France, 1988-1990

BACKGROUND: To compare socio-economic differences in mortality from ischemic heart disease and cerebrovascular disease in men in Spain and France during the 1988-90 period. METHODS: In Spain, the data were taken from the Eight Provinces Study, and in France the number of deaths was provided by the French National Health Institute(INSERM). The socio-economic differences in mortality have been estimated through the rate ratio. RESULTS: Farmers and manual workers presented higher mortality from ischemic heart disease and cerebrovascular disease than the professional and managerial group, while mortality in service workers showed a different pattern in both countries. CONCLUSIONS: The use of two occupational classes (manual/non manual) in international comparisons limits the interpretation of the results in this kind of studies.