Reduced HDL2 cholesterol subspecies and elevated postheparin hepatic lipase activity in older men with abdominal obesity and asymptomatic myocardial ischemia

Effects of an American Heart Association step I diet and weight loss on lipoprotein lipid levels in obese men with silent myocardial ischemia and reduced high-density lipoprotein cholesterol

Reduced plasma concentrations of high-density lipoprotein cholesterol (HDL-C) are a risk factor for coronary artery disease (CAD). In this study, we examined the sequential effects of an isocaloric American Heart Association (AHA) step I diet and a hypocaloric AHA step I diet (AHA step I diet + weight loss) on lipoprotein lipid levels in 14 middle-aged and older (60 +/- 6 years, mean +/- SD) obese (body mass index [BMI] > 27 kg/m2) nondiabetic men with exercise-induced silent myocardial ischemia (SI) and reduced HDL-C levels (0.85 +/- 0.14 mmol/L). Nine men of comparable age and obesity and with no evidence of exercise-induced ischemia that were evaluated longitudinally served as metabolic controls. In men with SI, after 3 months on the isocaloric AHA step I diet plasma triglyceride (TG) levels decreased by 26% (2.25 +/- 0.66 to 1.67 +/- 0.69 mmol/L, P < .005), cholesterol by 12% (5.24 +/- 0.84 to 4.62 +/- 0.78 mmol/L, P < .01), and low-density lipoprotein cholesterol (LDL-C) by 10% (3.40 +/- 0.69 to 3.05 +/- 0.70 mmol/L, P < .01). However, plasma HDL-C levels also decreased by 7% (0.85 +/- 0.14 to 0.79 +/- 0.13 mmol/L, P < .05). Subsequent weight loss (11 +/- 4 kg) in conjunction with the AHA step I diet resulted in an additional decrease of 24% in TG (P < .005), 10% in cholesterol (P < .05), and 10% in LDL-C (P < .05). Plasma HDL-C levels increased by 8% (P < .01), thereby correcting the decline seen on the AHA step I diet alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors for exercise-induced silent myocardial ischemia in healthy volunteers

This study determined the risk factors for exercise-induced silent ischemia (SI) in 281 apparently healthy volunteers aged 40 to 87 years and compared their risk factor profiles with those of 132 patients with overt coronary artery disease (CAD). SI (concordant exercise-induced asymptomatic ST-segment depression on electrocardiography and perfusion defects on tomographic thallium-201 scintigraphy) was detected in 37 of 225 men (16%), versus 2 of 56 women (4%, p < 0.05). The prevalence of SI increased with age from 6% in men aged < 55 years to 18% in men aged 55 to 70 years, and to 25% in men aged > 70 years (p < 0.001). Compared with the 118 men with concordant normal exercise electrocardiogram and thallium scan (normals), men with SI were older (p < 0.001), and had a higher waist-to-hip ratio (p < 0.005), higher plasma triglyceride levels (p < 0.001), and lower high-density lipoprotein (HDL) cholesterol levels (p < 0.001). In stepwise logistic regression analysis, age, waist-to-hip ratio, and HDL levels were independent predictors of SI in men. Compared with 108 men with overt CAD, men with SI were younger (67 +/- 2 vs 73 +/- 1 years, p < 0.001) but had similar plasma lipids and waist-to-hip ratio. Thus, older age, male gender, abdominal obesity, and reduced HDL levels--all well-established risk factors for overt CAD--were risk factors for exercise-induced SI in these asymptomatic volunteers.

Relations of plasma TG and HDL-C concentrations to body composition and plasma insulin levels are altered in men with small LDL particles

Low-density lipoprotein (LDL) subclass pattern B is characterized by a predominance of small, dense LDL particles (LDL peak particle size < or = 255 A), increased plasma triglyceride (TG) levels, reduced high-density lipoprotein (HDL) cholesterol levels, and glucose intolerance. This study tested the hypothesis that there are differences in the regulation of TG and HDL metabolism by insulin in patients with LDL pattern B. The study group comprised 160 healthy older (60 +/- 8 years, mean +/- SD) men. Forty-nine of the men (31%) had LDL pattern B. These men had a higher waist-to-hip ratio (WHR) (0.98 +/- 0.06 versus 0.95 +/- 0.06, P < .005) and lower maximal aerobic capacity (VO2max) (P < .005) than the 111 men of comparable age with a predominance of larger LDL particles (LDL peak particle size > 255 A, LDL pattern A). Men with LDL pattern B also had higher TG (1.76 +/- 0.60 versus 1.03 +/- 0.41 mmol/L, P < .0001) and lower HDL cholesterol (0.83 +/- 0.13 versus 1.06 +/- 0.29 mmol/L, P < .0001) and percent HDL2 subspecies (by gradient gel electrophoresis) (31 +/- 4 versus 43 +/- 6, P < .0001) levels than men with LDL pattern A, but the total cholesterol and LDL cholesterol levels did not differ between groups. Fasting glucose and insulin levels also did not differ between groups, but plasma glucose and insulin levels measured at 90 and 120 minutes during an oral glucose tolerance test were significantly higher in men with LDL pattern B.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of HDL subfractions on erythrocyte aggregation in hypercholesterolemic men. PCVMETRA Group

Recent studies have suggested that rheological mechanisms may be involved in the pathogenesis of ischemic syndromes in hyperlipidemias. We investigated the association between erythrocyte aggregation and components of lipoproteins in the blood of 60 normotensive, hypercholesterolemic men aged 45 +/- 8 years. The rheological parameters assessed were aggregation index (AI) and disaggregation shear rate threshold (gamma t) as determined by laser reflectometry, plasma fibrinogen, total serum protein, and hematocrit. The lipoprotein variables included total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol and its subfractions HDL2 cholesterol and HDL3 cholesterol, apolipoprotein (apo) B, apoA-I, HDL particles containing apoA-I without apoA-II (LpA-I), and HDL particles containing both apoA-I and apoA-II (LpA-I/A-II). Covariables considered for possible confounding effects were age, body mass index, and smoking behavior. Fibrinogen, total serum protein, and both aggregation parameters (AI and gamma t) were elevated in this hypercholesterolemic population. Univariate analysis showed that both AI and gamma t correlated positively with fibrinogen (P < .001) and total serum protein (P < .01) and negatively with HDL2 cholesterol (P < .01) and LpA-I (P < .01); gamma t also provided a positive correlation with LpA-I/A-II (P < .05). A multivariate model analysis demonstrated that HDL2 cholesterol, LpA-I, and LpA-I/A-II also emerged as significant factors influencing erythrocyte aggregation; 60% to 68% of the variance of AI and 47% to 64% of the variance of gamma t could be explained by these factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced adipose tissue lipoprotein lipase responses, postprandial lipemia, and low high-density lipoprotein-2 subspecies levels in older athletes with silent myocardial ischemia

Healthy older (64 +/- 1 years, mean +/- SEM) athletic (maximal oxygen consumption [VO2max] > 40 mL/kg/min) normocholesterolemic men with no prior history of coronary artery disease (CAD) were recruited for cardiovascular and metabolic studies. Thirty-three percent had asymptomatic exercise-induced ST segment depression on their exercise electrocardiogram (ECG), consistent with silent myocardial ischemia (SI). We hypothesized that abnormalities in high-density lipoprotein (HDL) and postprandial triglyceride (TG) metabolism may increase their risk for CAD. Compared with 12 nonischemic controls of comparable age, percent body fat, and VO2max, the 13 men with SI had decreased fasting HDL cholesterol ([HDL-C] 41 +/- 2 v 50 +/- 2 mg/dL, P < .001) and %HDL2b subspecies levels as measured by gradient gel electrophoresis (22 +/- 2 v 34 +/- 3, P < .001). Fasting plasma TG and low-density lipoprotein cholesterol (LDL-C) levels were the same in both groups. Although plasma glucose levels during an oral glucose tolerance test (OGTT) were similar in both groups, the total insulin area was higher in men with SI (P < .05). After consumption of a standard high-fat meal (680 kcal/m2 body surface area of a formula in which 86% of the calories were derived from fat), postprandial plasma TG, chylomicron-TG, and very-low-density lipoprotein (VLDL)-TG levels and postprandial areas were higher in men with SI (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

ApoE4 polymorphism increases the risk for exercise-induced silent myocardial ischemia in older men

The apolipoprotein (apo) E4 polymorphism is associated with increased risk for symptomatic coronary artery disease (CAD). This study examines whether the apo epsilon allele is associated with an increased risk for exercise-induced silent myocardial ischemia (SI) in healthy, older (62 +/- 7 years; mean +/- SD), normocholesterolemic, nonsmoking male volunteers. The apo epsilon 4 allele was present in 20 of 45 (44%) men with SI on graded exercise treadmill testing compared with 22 of 127 (17%) men of comparable age with normal exercise tests (P < .001), resulting in a crude relative risk of 2.57 (95% confidence limits, 1.57 to 4.23) for SI in men with the apo epsilon 4 allele compared with those without the epsilon 4 allele. Although the lipoprotein lipid levels did not differ between men with normal exercise tests and those with SI, the men with the apoE 4/3 phenotype had higher total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels than those with the apoE 2/3 and 3/3 phenotypes (P < .05). Men with SI and the apoE 4/3 phenotype were older (64 +/- 5 versus 57 +/- 8 years, P < .01) and leaner (P < .01) than the normal non-SI men with the apoE 4/3 phenotype. The older age of the men with SI and the apoE 4/3 phenotype is consistent with a progression of atherosclerosis over time. Men with SI and the apoE 3/3 phenotype were of comparable age and body composition to apoE 3/3 phenotype men with normal exercise tests. Thus, even in the presence of normal LDL-C levels, the apo epsilon 4 allele may predispose older men to SI.