Impact of postprandial lipaemia on low-density lipoprotein (LDL) size and oxidized LDL in patients with coronary artery disease

BACKGROUND

Remnant lipoprotein particles (RLPs) and oxidative stress are components of postprandial state. We investigated the concentrations of triglyceride-rich lipoproteins (TRLs), RLPs, low-density lipoprotein (LDL) size, and oxidized LDL (oxLDL) during alimentary lipaemia, and evaluated whether changes among these variables could be associated with the severity and extent of coronary artery disease (CAD).

MATERIALS AND METHODS

Eighty men and 27 women with clinically suspected CAD underwent quantitative coronary angiography (QCA). TRLs were isolated by density gradient ultracentrifugation before and 6 h after an oral fat load. RLPs were measured by an immunoseparation method, oxLDL by ELISA, and LDL size by gradient gel electrophoresis.

RESULTS

Triglycerides, apolipoprotein (apo) B-48, and apoB-100 concentration in Swedberg flotation units (Sf) > 400 and in Sf 12-400 fractions were markedly increased at 6 h. Postprandial cholesterol content of RLPs (RLP-C) correlated with respective triglycerides in Sf > 400 (r = 0.737) and Sf 12-400 (r = 0.857), apoB-48 in Sf > 400 (r = 0.710) and Sf 12-400 (r = 0.664), apoB-100 in Sf > 400 (r = 0.812) and Sf 12-400 (r = 0.533). RLP-C correlated with oxLDL both in fasting and in fed state (r = 0.482 and r = 0.543, respectively) and inversely with LDL size (r = -0.459 and r = -0.442, respectively). (P < 0.001 for all). OxLDL was elevated postprandially (P < 0.001). In multivariate analysis, oxLDL was a determinant of severity and extent of CAD.

CONCLUSION

Postprandial state is associated with oxidative stress. The magnitude of oxLDL increases during alimentary lipaemia and is associated with coronary atherosclerosis.

Systolic and diastolic heart failure--diagnostic and therapeutic dilemmas

Clinical suspicion of congestive heart failure (CHF) always requires a careful diagnostic workup. This comprises the verification of the presence of CHF (in contrast to other conditions that cause nonspecific phenomena such as shortness of breath and edema), evaluation of the underlying cause of heart failure, and assessment of left ventricular (LV) systolic function. In addition to clinical examination, echocardiography is warranted in most cases. On the basis of this information, patients can be selected for further studies, such as exercise testing, cardiac catheterization and coronary angiography. In view of the serious prognosis of heart failure, especially systolic CHF, the threshold for specialist consultation should be low. Although the classification of CHF into systolic and diastolic forms is complex, clinically meaningful data can be derived simply by determining whether LV systolic function is impaired (predominantly systolic CHF) or not (probable diastolic CHF). In the latter case, treatment is mainly symptomatic in addition to the management of the underlying condition (e.g. hypertension). In systolic CHF, considerable therapeutic advances have recently been made and it is important that patients receive appropriate care to improve their prognosis. These measures include angiotensin-converting enzyme inhibitors, beta-blockers and spironolactone.

Serum homocysteine, creatinine, and glucose as predictors of the severity and extent of coronary artery disease in asymptomatic members of high-risk families

BACKGROUND

There has been no previous study to determine the severity and extent of coronary artery disease (CAD) in subjects with no diagnosis or symptoms of CAD at the time of the angiography.

METHODS

Fifty-three subjects, who were siblings of patients with early onset CAD, underwent coronary angiography. Indices to describe per-patient characteristics of CAD were calculated, based on computer-aided quantitative coronary angiography. Clinical and laboratory characteristics were correlated to the angiographic parameters.

RESULTS

Serum total homocysteine (rho = 0.29, P < 0.05) and creatinine (rho = 0.47, P = 0.001) levels were related to the global atheroma burden index. The median of the atheroma burden index was two times higher in the top homocysteine quartile compared to the lowest quartile. The overall atheroma burden index correlated significantly with the fasting blood glucose level in all subjects. Diabetes, especially when albuminuria was present, was a powerful risk factor. In a multivariate analysis, only age and sex were independent predictors of atheroma burden.

CONCLUSIONS

Serum homocysteine and creatinine concentrations, and diabetes with albuminuria were found to be markers of the severity and extent of CAD in subjects of high-risk families without symptoms of CAD.

Family histories of Type II diabetes and hypertension predict intima-media thickness in patients with Type I diabetes

AIMS/HYPOTHESIS

Hyperglycaemia predicts microvascular complications but data on macrovascular disease are limited. We searched for predictors of carotid artery intima-media thickness in young adults with Type I (insulin-dependent) diabetes mellitus.

METHODS

A total of 71 children (F/M = 34/37) were followed after their diagnosis until they reached 32 +/- 1 years of age, when duration of diabetes averaged 22 +/- 1 years. Cardiovascular risk markers [lipids, blood pressure, smoking, urinary albumin excretion rate, lifetime glycaemic exposure (A(1c) months), exercise habits, alcohol consumption, family history] were evaluated at age 21 +/- 1 for the baseline examination and at age 32 +/- 1 years for the follow-up examination years. During follow-up, intima-media thickness of common and internal carotid arteries and the carotid bulb were quantitated using a high-resolution B-mode ultrasound.

RESULTS

In univariate analysis, age, BMI, blood pressure, lifetime glycaemic exposure, a positive family history of Type II (non-insulin-dependent) diabetes mellitus, hypertension and cardiovascular disease were predictors of carotid intima-media thickness. In multivariate analysis, a positive family history of Type II diabetes predicted maximal ( p< 0.05) and common ( p< 0.005) carotid artery intima-media thickness, family history of hypertension predicted increases in maximal ( p< 0.04), and far wall ( p< 0.006) carotid artery intima-media thickness, and lifetime glycaemic exposure was an independent predictor of increased carotid bulb thickness ( p< 0.03).

CONCLUSION/INTERPRETATION

Positive family histories of Type II diabetes and hypertension are independent predictors of carotid intima-media thickness in patients with Type I diabetes, and could therefore predispose these patients to atherosclerosis

Remnant-like lipoprotein particle cholesterol concentration and progression of coronary and vein-graft atherosclerosis in response to gemfibrozil treatment

Remnant lipoproteins such as chylomicron and very low density lipoprotein (VLDL) remnants have been implicated in the progression of coronary atherosclerosis. Recently, a novel method for the determination of the remnant-like lipoprotein particle cholesterol (RLP-C) concentration was developed based on immunoaffinity-separation of plasma. The compositional characteristics of RLP are strikingly similar to those of postprandially modified VLDL. In addition, the method also detects chylomicron remnants. We investigated the relationship between the plasma RLP-C concentration and the angiographic outcome of the 2-year, randomised, placebo-controlled Lipid Coronary Angiography Trial (LOCAT), which used gemfibrozil as lipid lowering agent. The RLP-C response to gemfibrozil treatment has not been described before. Gemfibrozil reduced the median RLP-C concentration by 34%. The on-treatment RLP-C concentration was significantly associated with the progression of the minimum lumen diameter (MLD) (P<0.004). The plasma levels of RLP-C as well as the change in response to treatment was closely associated with plasma triglycerides and the association between on-treatment RLP-C concentration and progression of MLD was not independent of plasma triglycerides. A significant relation was seen between RLP-C and the occurrence of new lesions in vein grafts. Subjects with one new lesion had an approximately 25% higher on-treatment RLP-C concentration and the four patients showing two new lesions had a 100% higher RLP-C concentration than patients without vein graft stenosis. A total of 19 out of 23 subjects having one new lesion, and all four patients showing two new lesions, were assigned to the placebo group. We conclude that the RLP-C concentration, which is likely to reflect the plasma cholesterol contained in postprandially modified VLDL and chylomicron remnants, is strongly associated with angiographically verified progression of focal coronary atherosclerosis, and that lowering of RLPs prevents vein graft stenosis.

Temporal age-related changes in spectral, fractal and complexity characteristics of heart rate variability

Cross-sectional studies have suggested that heart rate (HR) variability, analysed using traditional time and frequency domain methods, is related to ageing, but no longitudinal studies have estimated the age dependence of HR fluctuation. This study evaluated temporal age-related changes in 12-h measures of HR variability among 109 patients with coronary artery disease (CAD), who underwent repeat Holter recordings at 32-month intervals. Time and frequency domain measures, along with fractal and complexity measures of HR variability, were determined at the baseline and after 32 months. Changes in HR dynamics were compared with various laboratory variables, exercise data and angiographic progression of CAD. Traditional time and frequency domain measures of HR variability did not change significantly during the follow-up, but the power-law scaling slope decreased from -1.29 +/- 0.20 to -1.36 +/- 0.23 (P<0.01) and the short-term fractal exponent (alpha1) of HR dynamics from 1.29 +/- 0.14-1.22 +/- 0.18 (P<0.001). The approximate entropy value also decreased from 1.00 +/- 0.19 to 0.95 +/- 0.18 (P<0.05). The changes in HR behaviour were not related to demographic data, laboratory values or angiographic progression of CAD. Only a weak correlation was observed between the change in the power-law slope and the baseline glucose value (P<0.05). This longitudinal study shows that the fractal characteristics of HR dynamics and the complexity properties of R-R intervals undergo rapid changes along with ageing, and that fractal and complexity analysis techniques are more sensitive than traditional analysis methods in documenting temporal age-related changes in HR behaviour.

Cholesterol efflux capacity in vitro predicts the severity and extent of coronary artery disease in patients with and without type 2 diabetes

OBJECTIVE

To investigate the relation between severity and extent of coronary artery disease (CAD) and in vitro cholesterol efflux capacity.

DESIGN

This study consisted of 46 type 2 diabetic, and 42 nondiabetic men undergoing coronary angiography. Quantitative coronary angiography was used to estimate the severity, extent, and overall "atheroma burden" of CAD. The capacity of patient plasma to induce cholesterol efflux from cultured Fu5AH rat hepatoma cells was measured in vitro.

RESULTS

In the combined study population (n = 88), there was a significant inverse correlation between efflux and global atheroma burden (r = -0.23, p < 0.05). In the diabetic group, the global atheroma burden index was independently associated both with cholesterol efflux and with LpA-I levels. However, in the nondiabetic CAD group this association was lost when efflux and LpA-I levels were included in the same model.

CONCLUSION

The present study demonstrated that efflux capacity was inversely associated with the severity and extent of CAD. In the diabetic group this association was independent of LpA-I levels, suggesting impaired antiatherogenic potential of these particles in type 2 diabetic patients.

Determinants of the severity and extent of coronary artery disease in patients with type-2 diabetes and in nondiabetic subjects

BACKGROUND

Factors predicting the anatomic distribution and the severity and extent of coronary atherosclerosis in patients with clinically manifest coronary artery disease (CAD) for type-2 diabetic patients could be different than those for nondiabetic patients.

OBJECTIVE

To study the determinants of severity and extent of CAD in consecutive patients with type 2 diabetes mellitus, compared with those for matched nondiabetic patients, undergoing clinically indicated coronary angiography.

METHODS

Coronary angiograms of 48 men and seven women with type-2 diabetes and an equal number of nondiabetic subjects were analyzed quantitatively. Scores reflecting severity and extent of CAD were compared with potential risk factors using univariate correlation analyses and multivariate regression models.

RESULTS

For the diabetics, a global coronary atheroma burden index was independently and directly related to age (P = 0.022) and to level of intermediate-density lipoprotein cholesterol (P = 0.055), and inversely to level of particles of a subtype of high-density lipoprotein (P = 0.022). Several angiographic indexes were related to the duration of diabetes and control of glycemia. For the nondiabetic group, global atheroma burden was independently related to age (P = 0.028), a history of hypertension (P = 0.028), and concentration of low-density lipoprotein (P = 0.013), and inversely to level of apolipoprotein A-I (P = 0.008). The duration of coronary disease and a history of smoking were also predictive of severe coronary atherosclerosis among nondiabetic patients.

CONCLUSIONS

Classical risk factors are strong predictors of the severity and extent of coronary atherosclerosis in nondiabetic patients, but the most important determinants for type-2 diabetic patients are levels of triglyceride-rich lipoproteins and apolipoprotein A-I-containing particles of high-density lipoprotein, and factors directly related to diabetes.

Angiographic severity and extent of coronary artery disease in patients with type 1 diabetes mellitus

Studies of the characteristics of coronary artery disease (CAD) in diabetic patients have shown conflicting results. Only 2 studies exploring the severity of CAD, specifically in type 1 diabetes, have been published, and neither of them has used computer-aided quantitative coronary angiography. This retrospective study comprised 64 (24 women and 40 men) type 1 diabetic patients and nondiabetic control subjects. To estimate the severity, extent, and overall "atheroma burden" of CAD, we used quantitative coronary angiographic-based segmental analysis of coronary angiograms. Type 1 diabetic patients had greater global severity (p < 0.001), global extent (p < 0.001), and global atheroma burden (p < 0.001) indexes than nondiabetic control subjects. Quantitative coronary angiographic-derived indexes of CAD were, on average, 1.4- to 4.3-fold higher in diabetic than in nondiabetic patients. These differences were particularly marked in women. We found that type 1 diabetic patients with a clinical indication for coronary angiography, especially women, have more severe, extensive, and distal type of CAD than individually matched nondiabetic control patients. Our findings, including a loss of sex difference for CAD among type 1 diabetic patients and a marked impact of type 1 diabetes in women, are not explained by established risk factors.

Postprandial metabolism of apolipoprotein B-48- and B-100-containing particles in type 2 diabetes mellitus: relations to angiographically verified severity of coronary artery disease

The aim of the present cross-sectional angiographic study was to examine if there is a relationship between the severity of CAD and postprandial lipemia in patients with type 2 diabetes mellitus. Special emphasis was directed to determining the contribution of apolipoprotein B-48 (apoB-48)-containing and B-100 (apoB-100)-containing triglyceride-rich particles to the magnitude of postprandial lipemia and degree of CAD. The role of apolipoprotein E (apoE) phenotype as a modulator of postprandial lipemia was also evaluated. The severity of CAD was determined by a quantitative coronary angiography and the subjects were classified into two groups based on the presence (severe CAD) or absence (mild CAD) of at least 50% stenosis in a major coronary vessel. The study population consisted of 43 subjects (31 men and 12 women) with fair glycemic control and comparable fasting lipids and body mass index. Postprandial responses of TG, apoB-48 and apoB-100 in lipoprotein subfractions (chylomicrons, VLDL1, VLDL2 and IDL) were determined after a fat load. Type 2 diabetic patients exhibited the classical dyslipidemia of the insulin resistance syndrome and delayed clearance of both hepatic and intestinal particles. Fasting or postprandial lipid or lipoprotein measurements, including apoB-48 and apoB-100 concentrations, did not differ between the groups. The presence or absence of apoE-4 allele did not significantly influence postprandial lipemia. The severity of the most significant coronary stenosis in angiography correlated with plasma and with chylomicron area under curve (AUC) for TG (n=27) and chylomicron AUC for apoB-48 (n=20). The strongest correlate of maximal stenosis was area under incremental curve (AUIC) for apoB-100 in IDL fraction (r=0.548, P=0. 012, n=20). In conclusion, postprandial apoB-48 and apoB-100 metabolism in triglyceride rich lipoproteins is distorted in type 2 diabetic patients, even in those with only mild CAD. The data suggest that postprandial change in small remnant particle numbers may contribute to the severity of CAD in type 2 diabetes.

Fibrinolytic proteins and progression of coronary artery disease in relation to gemfibrozil therapy

Impaired fibrinolytic function, mainly due to increased plasma plasminogen activator inhibitor-1 (PAI-1) activity, is common in patients with manifest coronary artery disease (CAD) and a predictor of recurrent cardiovascular events. We investigated the relationships of plasma tissue-type plasminogen activator (tPA) and PAI-1 antigen levels, plasma PAI-1 activity and PAI 4/5-guanosine (4G/5G) genotype to CAD progression in 203 middle-aged men participating in the Lopid Coronary Angiography Trial (LOCAT). A higher tPA antigen concentration, whether baseline or on-trial, was associated with a more severe global angiographic response (p < 0.05), an association mainly accounted for by progression of diffuse lesions in graft-affected segments (change in per-patient means of average diameters of segments haemodynamically related to bypass grafts). Plasma PAI-1 activity and mass concentration and 4G/5G PAI-1 genotype were unrelated to angiographic outcome measurements. tPA and PAI-1 antigen increased significantly in the gemfibrozil group (+11.3% and + 16.4%, respectively, p < 0.001), whereas there was no treatment effect on PAI-1 activity (median change 0.0%). It is concluded that fibrinolytic function does not substantially influence progression of CAD as assessed by angiography in middle-aged men. Furthermore, pronounced long-term lowering of serum triglycerides by gemfibrozil treatment does not significantly affect the plasma PAI-1 activity level but increases the plasma tPA and PAI-1 antigen concentrations.

Catheter-mediated vascular endothelial growth factor gene transfer to human coronary arteries after angioplasty

Blood vessels are among the easiest targets for gene therapy. However, no data are available about the safety and feasibility of intracoronary gene transfer in humans. We studied the safety and efficacy of catheter-mediated vascular endothelial growth factor (VEGF) plasmid/liposome (P/L) gene transfer in human coronary arteries after percutaneous translumenal coronary angioplasty (PTCA) in a randomized, double-blinded, placebo-controlled study. The optimized angioplasty/gene delivery method was previously shown to lead to detectable VEGF gene expression in human peripheral arteries as analyzed from amputated leg samples. Gene transfer to coronary arteries was done with a perfusion-infusion catheter, using 1000 microg of VEGF or beta-galactosidase plasmid complexed with 1000 microl of DOTMA:DOPE liposomes. Ten patients received VEGF P/L, three patients received beta-galactosidase P/L, and two patients received Ringer lactate. Gene transfer to coronary arteries was feasible and well tolerated. Except for a slight increase in serum C-reative protein in all study groups, no adverse effects or abnormalities in laboratory parameters were detected. No VEGF plasmid or recombinant VEGF protein was present in the systemic circulation after the gene transfer. In control angiography 6 months later, no differences were detected in the degree of coronary stenosis between treatment and control groups. We conclude that catheter-mediated intracoronary gene transfer performed after angioplasty is safe and well tolerated and potentially applicable for the prevention of restenosis and myocardial ischemia.

Delayed clearance of postprandial large TG-rich particles in normolipidemic carriers of LPL Asn291Ser gene variant

The carrier frequency of Asn291Ser polymorphism of the lipoprotein lipase (LPL) gene is 4;-6% in the Western population. Heterozygotes are prone to fasting hypertriglyceridemia and low high density lipoprotein (HDL) cholesterol concentrations especially when secondary factors are superimposed on the genetic defect. We studied the LPL Asn291Ser gene variant as a modulator of postprandial lipemia in heterozygote carriers. Ten normolipidemic carriers were compared to ten control subjects, who were selected to have similar age, sex, BMI, and apolipoprotein (apo)E-phenotype. The subjects were given a lipid-rich mixed meal and their insulin sensitivity was determined by euglycemic hyperinsulinemic clamp technique. The two groups had comparable fasting triglycerides and glucose utilization rate during insulin infusion, but fasting HDL cholesterol was lower in carriers (1.25 +/- 0.05 mmol/L) than in the control subjects (1. 53 +/- 0.06 mmol/L, P = 0.005). In the postprandial state the most pronounced differences were found in the very low density lipoprotein 1 (VLDL1) fraction, where the carriers displayed higher responses of apoB-48 area under the curve (AUC), apoB-100 AUC, triglyceride AUC, and retinyl ester AUC than the control subjects. The most marked differences in apoB-48 and apoB-100 concentrations were observed late in the postprandial period (9 and 12 h), demonstrating delayed clearance of triglyceride-rich particles of both hepatic and intestinal origin. Postprandially, the carriers exhibited enrichment of triglycerides in HDL fraction. Thus, in normolipidemic carriers the LPL Asn291Ser gene variant delays postprandial triglyceride, apoB-48, apoB-100, and retinyl ester metabolism in VLDL1 fraction and alters postprandial HDL composition compared to matched non-carriers.

Heart rate variability and progression of coronary atherosclerosis

Low heart rate (HR) variability is associated with increased risk of cardiovascular morbidity and mortality, but the causes and mechanisms of this association are not well known. This prospective study was designed to test the hypothesis that reduced HR variability is related to progression of coronary atherosclerosis. Average HR and HR variability were analyzed in 12-hour ambulatory ECG recordings from 265 qualified patients participating in a multicenter study to evaluate the angiographic progression of coronary artery disease in patients with prior coronary artery bypass surgery and low high-density lipoprotein cholesterol concentrations (<1.1 mmol/L). Participants were randomized to receive a placebo or gemfibrozil therapy. The progression of coronary atherosclerosis was estimated by quantitative, computer-assisted analysis of coronary artery stenoses from the baseline angiograms and from repeated angiograms performed an average of 32 months later. The progression of focal coronary atherosclerosis of the patients randomized to placebo therapy was more marked in the tertile with the lowest standard deviation of all normal to normal R-R intervals (SDNN, 74+/-13 ms; mean decrease in the per-patient minimum luminal diameter -0.17 mm; 95% confidence interval [CI], -0.23 to -0.12 mm) than in the middle tertile (SDNN, 107+/-7 ms; mean decrease -0.05 mm; 95% CI, -0.08 to -0.01 mm) or highest tertile (SDNN, 145+/-25 ms; mean change 0.01 mm; 95% CI, -0. 04 to 0.02 mm) (P<0.001 between the tertiles). This association was abolished by gemfibrozil. SDNN was lower (P<0.001) and minimum HR was faster (P<0.01) in the patients with marked progression than in those with regression of focal coronary atherosclerosis. In multiple regression analysis including HR variability, minimum HR, demographic and clinical variables, smoking, blood pressure, glucose, lipid measurements and lipid-modifying therapy, progression of focal coronary atherosclerosis was independently predicted by the SDNN (beta=0.24; P=0.0001). Low HR variability analyzed from ambulatory ECG predicts rapid progression of coronary artery disease. HR variability provided information on progression of focal coronary atherosclerosis beyond that obtained by traditional risk markers of atherosclerosis.

Impaired endothelium-dependent vasodilation in type 2 diabetes. Relation to LDL size, oxidized LDL, and antioxidants

OBJECTIVE

To search for determinants of endothelial dysfunction in type 2 diabetes.

RESEARCH DESIGN AND METHODS

We performed a comprehensive analysis of cardiovascular risk markers and measured blood flow responses to endothelium-dependent (acetylcholine [ACh] and NG-monomethyl-L-arginine) and -independent (sodium nitroprusside [SNP]) vasoactive agents in 30 nonsmoking men with type 2 diabetes (age 51 +/- 1 years, BMI 27.8 +/- 0.4 kg/m2, HbA1c 7.4 +/- 0.3%) and 12 matched normal control men.

RESULTS

ACh-induced vasodilation was 37% lower in type 2 diabetic (6.1 +/- 0.5) than in normal subjects (9.7 +/- 1.5 ml.dl-1.min-1, P < 0.01), while flows during SNP were similar (9.1 +/- 0.6 vs. 9.9 +/- 1.3 ml.dl-1.min-1, NS). The ratio of endothelium-dependent vs. -independent flow (ACh:SNP ratio) was 31% lower in type 2 diabetic (0.70 +/- 0.05) than in normal subjects (1.10 +/- 0.18, P < 0.01). Total (2.2 +/- 0.4 vs. 1.3 +/- 0.2 mmol/l, P < 0.05), VLDL, and intermediate-density lipoprotein triglycerides were significantly higher, and the mean LDL particle diameter was significantly smaller in type 2 diabetic than in normal subjects. The lag times for LDL oxidation by Cu2+ in vitro were similar in patients with type 2 diabetes (183 +/- 7) and in normal subjects (183 +/- 9 min, NS). Measured and calculated (sum of concentration of individual antioxidants in serum) total peroxyl radical-trapping capacities (TRAPs) were comparable between the groups. In the patients with type 2 diabetes, LDL size was significantly correlated with endothelium-dependent vasodilation (r = 0.43, P < 0.05), serum triglycerides (r = -0.75, P < 0.001), and the lag time for LDL oxidation in vitro (r = 0.38, P < 0.05). HbA1c was inversely correlated with the lag time for LDL oxidation in vitro (r = -0.41, P < 0.05) and TRAP.

CONCLUSIONS

In summary, patients with type 2 diabetes exhibited impaired endothelium-dependent vasodilation in vivo, elevated serum triglycerides, decreased LDL size, and normal antioxidant capacity. Of these parameters, LDL size was significantly correlated with endothelial function.

Significance of graft occlusion and coronary atherosclerosis 5 years after coronary artery bypass grafting. A quantitative angiographic study with serial exercise testing

OBJECTIVE

To evaluate the relative importance of graft occlusions and progression of atherosclerosis in coronary arteries as causes of the occurrence of angina pectoris and impairment of physical performance 5 years after coronary artery bypass surgery.

DESIGN

A 5-year follow-up study.

SETTING

University hospital in south-western Finland.

SUBJECTS

Altogether, 174 consecutive electively operated bypass patients.

MAIN OUTCOME MEASURES

Serial clinical evaluation and bicycle exercise tests (pre-operatively, at 6 months, and at 1 and 5 years). Quantitative coronary angiography pre-operatively and 5 years after the surgery.

RESULTS

Subjects with patent grafts had fewer angina pectoris symptoms at the 5-year follow-up (24 vs. 52%, P = 0.001) and were treated less frequently with long-acting nitrates (3 vs. 15%, P = 0.037) than subjects with graft occlusions. Fewer of them were in classes II-III of the functional classification of the Canadian Cardiovascular Society (39 vs. 74%, P = 0.001). The exercise test was interrupted less often because of chest pain (23 vs. 41%, P = 0.03) and improvement in exercise test variables during the follow-up period was significantly greater in subjects with patent grafts (P<0.002). Amongst patients without graft occlusions, those with new > or =50% diameter stenoses in coronary arteries were more often in functional classes II-III (59 vs. 32%, P = 0.03) than those without new stenoses, but the groups were similar with respect to angina pectoris and exercise tests variables. In patients with graft occlusions, those with and without new > or =50% diameter stenoses were similar with respect to functional class, angina pectoris and exercise test variables.

CONCLUSIONS

Angina pectoris and impairment of physical capacity 5 years after coronary artery bypass grafting are mainly due to occlusion of bypass grafts and not to progression of atherosclerosis in coronary arteries.

Angiographic changes in saphenous vein grafts and atherosclerosis risk factors. A 5-year study with serial measurements of serum lipids and lipoproteins

The association between cardiovascular risk factors and stenosis or occlusion of saphenous vein grafts was analysed in a prospective 5-year study of 176 unselected patients with coronary artery bypass grafting (CABG). Methods included serial measurements of serum lipids and lipoproteins, determination of apolipoprotein E phenotype, lipoprotein (a) levels 5 years postoperatively, and subcutaneous fat biopsy to determine the fatty acid composition before and one year after CABG. Graft angiography with quantitative analysis of angiograms was performed at the end of follow-up. A coronary artery with diameter < or = 1.5 mm was associated with occlusion of vein grafts (p < 0.01). The mean levels of serum lipids and lipoproteins, other traditional risk factors for atherosclerosis, and subcutaneous fatty acid composition were similar in patients with and without graft occlusion, and similar when the maximum diameter of non-occluded grafts was < 50% vs > or = 50%, and < 25% vs > or = 25%. High lipoprotein (a) concentration tended to be associated with obstructive changes in vein grafts. Our data indicate that, because lipids, lipoproteins and other traditional cardiovascular risk factors do not predict occlusion or stenosis of saphenous vein grafts five years after CABG, it is not currently possible to predict directly from the levels of these risk factors which patients are likely to benefit from pharmacological or other interventions.

Postprandial lipid metabolism in diabetes

Postprandial lipemia is an inherent feature of diabetic dyslipidemia and highly prevalent in diabetic patients even with normal fasting triglyceride concentrations. Postprandial lipemia is characterized by long residence time of chylomicron and VLDL remnants in the circulation. Insulin resistance causes increased flux of free fatty acids, and thus enhanced VLDL apolipoprotein B (apo B) synthesis in the liver. Together with chylomicron and VLDL remnant competition for the common removal mechanisms the increased substrate input results in exaggerated and prolonged postprandial lipemia. Studies using both apo B-48 and retinyl esters as a marker for intestinally derived particles have shown that increased postprandial lipemia does not predict the presence or absence of coronary artery disease between non-insulin-dependent diabetes mellitus (NIDDM) subjects. Recent data have shown that postprandial triglyceride-rich remnants are atherogenic, and postprandial hypertriglyceridemia contributes to the metabolic disturbances transforming LDL and HDL subclasses into more atherogenic direction in diabetic subjects.

Associations between lipoproteins and the progression of coronary and vein-graft atherosclerosis in a controlled trial with gemfibrozil in men with low baseline levels of HDL cholesterol

BACKGROUND

Lipid-lowering secondary-prevention trials of coronary artery disease (CAD) have implicated triglyceride-rich lipoproteins as the main determinants of angiographic progression after elevated LDL cholesterol levels have been lowered with therapy. The present study focuses on the lipoprotein determinants of angiographic CAD progression in men with low HDL cholesterol concentration as their main baseline lipid abnormality who underwent 32 months of randomized therapy with gemfibrozil or placebo.

METHODS AND RESULTS

Men who had undergone coronary bypass surgery (n=372) completed a randomized, placebo-controlled study with gemfibrozil 1200 mg/d. They were selected primarily for HDL cholesterol levels that corresponded to the lowest third for middle-aged men. Average baseline lipid and lipoprotein levels were serum triglyceride, 1.60; serum cholesterol, 5.17; ultracentrifugally separated LDL cholesterol, 3.43; HDL2 cholesterol, 0.41; and HDL3 cholesterol, 0. 61 mmol/L. In the gemfibrozil group, these levels were reduced on average by 40%, 9%, and 6% or increased by 5% and 9%, respectively. On-trial IDL and LDL triglyceride and cholesterol levels significantly predicted global angiographic progression, taking into account changes in native segments and in bypass grafts. HDL3 but not HDL2 cholesterol concentration was associated with protection against progression, especially focal disease in native coronary lesions. VLDL was the lipoprotein most predictive of new lesions in vein grafts; IDL was also significantly related.

CONCLUSIONS

This study expands the previous evidence of the triglyceride-rich lipoproteins, especially IDL, as predictors of angiographic progression of CAD but does not negate the significance of mildly elevated LDL levels. Of the HDL subfractions, only HDL3 was protective in this group of men selected for their low initial HDL levels.

The 5A/6A polymorphism in the promoter of the stromelysin-1 (MMP-3) gene predicts progression of angiographically determined coronary artery disease in men in the LOCAT gemfibrozil study. Lopid Coronary Angiography Trial

The relationship between the 5A/6A stromelysin-1 promoter polymorphism and progression of angiographically determined coronary artery disease (CAD) has been examined in men treated for 32 months with gemfibrozil or placebo in the Lopid Coronary Angiography Trial (LOCAT). The frequency of the 5A allele was 0.40 (95%, CI, 0.36-0.43), and in the sample as a whole 12% of the men were homozygous for the 5A allele. In the placebo group, diffuse progression of disease was, on average, completely prevented in men with the genotype 5A/5A as measured by a 0.30% increase in mean average diameter of the coronary artery segments (ADS), compared with a mean 1.79% decrease in the combined group with the genotype 5A6A or 6A6A (mean +/- S.E.M., +0.007 +/- 0.020 mm vs. -0.043 +/- 0.0.08 mm, P = 0.03). A similar relationship with genotype was seen for disease progression determined by the mean minimal luminal diameter (MLD); with the 5A5A group decreasing by an average of 1.72% compared with 5.54% in the 5A/6A plus 6A/6A group (-0.029 +/- 0.034 mm vs. -0.102 +/- 0.013 mm, P = 0.06). In the gemfibrozil-treated group, the effect on disease progression associated with the 5A/6A alleles was of a similar pattern as in the placebo group, but the effect was less marked and was not statistically significant. This study confirms the previously reported beneficial effect on disease progression associated with the 5A allele and raises the possibility that patients with CAD who are homozygous for the 6A allele, and who represent 25-30% of the population, may be at particular risk of rapid progression of disease and may require particularly aggressive lipid lowering therapy to prevent disease progression.

Components of the insulin resistance syndrome are associated with progression of atherosclerosis in non-grafted arteries 5 years after coronary artery bypass surgery

AIMS

Risk factors for progression of atherosclerosis in non-grafted coronary arteries were examined in a prospective 5-year follow-up study of 228 consecutive coronary artery bypass surgery patients, with the main emphasis on insulin resistance syndrome.

METHODS AND RESULTS

Serum lipids and lipoproteins were measured pre-operatively and 1, 2, 3 and 5 years after surgery; and a baseline oral glucose tolerance test with plasma insulin determinations was performed pre-operatively. Progression of atherosclerosis was assessed by means of computer-based quantitative coronary angiography. Compared to subjects without progression, the patients with progression of atherosclerotic lesions had a higher body mass index both at baseline (P = 0.022) and at 5 years (P = 0.007), were more often treated for hypertension at baseline (P = 0.008) and at 5 years (P = 0.012), used diuretics more often during the follow-up period (P = 0.002), had a larger blood glucose area under the curve (P = 0.015) and a lower insulin sensitivity index (P = 0.006) in the baseline oral glucose tolerance test, had a higher serum total cholesterol concentration at baseline (P = 0.044), and a higher serum triglyceride concentration (P = 0.005) during the whole follow-up period. Clustering of the components of insulin resistance syndrome at baseline was more frequently found in patients with progression of atherosclerotic lesions than in patients without progression (P = 0.025). For example, for patients with < or = 1 component, the risk of progression was 17%, while for patients with > or = 5 components the risk was 67%. As compared to the other patients, those with new atherosclerotic lesions had a lower insulin sensitivity index at baseline (P = 0.033), and a lower serum high density lipoprotein cholesterol concentration during the follow-up period (P = 0.033).

CONCLUSION

In addition to high serum cholesterol, the components of the insulin resistance syndrome are associated with progression of atherosclerosis in non-grafted coronary arteries 5 years after coronary artery bypass surgery.

Comparison of three fatty meals in healthy normolipidaemic men: high post-prandial retinyl ester response to soybean oil

BACKGROUND

Oral fat tolerance tests (FTTs) have been widely used as a tool to investigate post-prandial lipaemia. However, there is no consensus regarding the type and amount of fat used in the tests.

METHODS

We compared three commonly used FTTs, each containing 63 g of fat: a mixed meal, a liquid cream meal and a liquid soybean oil meal. The study group consisted of 10 healthy normolipidaemic men. We measured triglycerides (TGs), retinyl esters (REs), apolipoprotein E (apoE), apolipoprotein B-48 (apoB-48) and apolipoprotein B-100 (apoB-100) in plasma and in triglyceride-rich lipoprotein (TRL) fractions separated by density-gradient ultracentrifugation at baseline and 3, 4, 6, and 8 h after the FTTs.

RESULTS

We observed similar TGs, apoE, apoB-48 and apoB-100 responses after all three FTTs, despite the different fatty acid composition of the meals. In contrast, the commonly used marker for exogenous particles, RE, differed clearly when polyunsaturated (soybean oil) and saturated fat (cream or mixed meal) were used. The RE response in plasma (P < 0.005, repeated measures ANOVA), in chylomicrons (P < 0.013) and in very low-density lipoprotein (VLDL) 1 (P < 0.017), as well as the RE area under the incremental curve in plasma and chylomicron fractions, were markedly increased after the soybean oil meal compared with the mixed meal and cream meal tests. The peak of RE response occurred parallel to the responses of other markers (i.e. TG or apoB-48) of post-prandial TRL during soybean oil meal. In contrast, RE peak concentration was delayed after saturated fat-containing meals. After soybean oil, FTT plasma cholesterol concentration was lower and the chylomicron cholesterol concentration was higher compared with mixed or cream meals, but no differences were detected in post-prandial high-density lipoprotein (HDL)-cholesterol concentration.

CONCLUSION

When the amount of fat is similar, post-prandial responses of TG, apoE, apoB-48, apoB-100 and HDL-cholesterol were comparable after different FTTs.

Prevention of the angiographic progression of coronary and vein-graft atherosclerosis by gemfibrozil after coronary bypass surgery in men with low levels of HDL cholesterol. Lopid Coronary Angiography Trial (LOCAT) Study Group

BACKGROUND

Studies have shown that treatment of hyperlipidemia, especially lowering of plasma LDL levels, retards the progression of coronary atherosclerosis and prevents clinical cardiovascular events. No such studies have focused on subjects with low levels of HDL cholesterol.

METHODS AND RESULTS

We randomly assigned 395 post-coronary bypass men, who had an HDL cholesterol concentration < or = 1.1 mmol/L and LDL cholesterol < or = 4.5 mmol/L, to receive gemfibrozil 1200 mg/d or placebo. Coronary angiography was performed at baseline and after, on average, 32 months of therapy. Changes in coronary dimensions were assessed by computer-assisted analysis. Average on-trial serum triglyceride concentrations were 1.69+/-0.68 and 1.02+/-0.37, total cholesterol 5.48+/-0.68 and 4.83+/-0.63, LDL cholesterol 3.84+/-0.59 and 3.39+/-0.56, and HDL cholesterol 0.88+/-0.15 and 0.98+/-0.17 mmol/L in the placebo and gemfibrozil groups, respectively (mean+/-SD, each P<.001). The change in per-patient means of average diameters of native coronary segments was -0.04+/-0.11 mm in the placebo group and -0.01+/-0.10 mm in the gemfibrozil group (P=.009). The equivalent changes in minimum luminal diameters of stenoses were -0.09+/-0.18 and -0.04+/-0.15 mm, respectively (P=.002). A similar, albeit nonsignificant, trend toward treatment benefit was found in the predefined primary study end point, segments unaffected by grafts and those distal to graft insertions. In aortocoronary bypass grafts, 23 subjects (14%) assigned to placebo had new lesions in the follow-up angiogram, compared with 4 subjects (2%) assigned to gemfibrozil (P<.001).

CONCLUSIONS

Gemfibrozil therapy retarded the progression of coronary atherosclerosis and the formation of bypass-graft lesions after coronary bypass surgery in men with low HDL cholesterol as their main lipid abnormality.

Postprandial elevation of ApoB-48-containing triglyceride-rich particles and retinyl esters in normolipemic males who smoke

Smokers have an increased risk for coronary artery disease (CAD), which can only partly be explained by fasting lipoprotein changes. Recent studies have indicated that smokers express metabolic abnormalities characteristic of insulin resistance syndrome. A preliminary study reported an increased postprandial triglyceride (TG) response in smokers compared with nonsmokers. To investigate the effect of smoking on postprandial lipemia, a fat-rich mixed meal (837 kcal, 63 g of fat) was served to 12 healthy smokers and 12 controls with similar fasting lipoprotein profiles, body composition, and lifestyles. Blood was drawn before and 3, 4, 6, and 8 hours postprandially, and triglyceride-rich lipoprotein (TRL) fractions (chylomicrons, VLDL1, VLDL2, and IDL) were separated with density gradient ultracentrifugation. Pre- and postprandial TG, retinyl esters (RE), apolipoprotein B-48 (apoB-48) and B-100 (apoB-100) were measured in each fraction. Smokers showed a significantly increased postprandial TG response in chylomicrons, VLDL1, and VLDL2. The areas under the incremental curve (AUIC) of apoB-48 in chylomicrons (2.83 +/- 0.84 versus 0.56 +/- 0.17; P < .05) and VLDL1 (10.17 +/- 1.96 versus 2.95 +/- 2.44; P = < .01) were markedly higher in smokers than in controls. Changes of RE responses of all TRL fractions were consistent with those of apoB-48. Postprandial apoB-100 concentrations and lipolytic enzymes were similar between the two groups. In conclusion, smokers have the syndrome of impaired TG tolerance because of defective clearance of chylomicrons and their remnants. Prolonged residence time of atherogenic remnant particles may constitute a significant risk factor for CAD in smokers.

Phenotype expression in familial combined hyperlipidemia

Familial combined hyperlipidaemia (FCHL) is one of the most common hereditary disorders predisposing to early coronary death. The affected family members have elevations of serum total cholesterol, triglycerides or both. Despite intensive research efforts the genetic and metabolic defects underlying this complex disorder are still unknown. To dissect the metabolism and genetics of FCHL the phenotype of an individual must be precisely defined. We assessed the influence of different diagnostic criteria on the phenotype definition and studied factors affecting the phenotype expression in 16 large Finnish families (n = 255) with FCHL. The fractile cut-points used to define abnormal lipid values had a profound influence on the diagnosis of FCHL. If the 90th percentile cut-point was used, approximately 45% of the family members were affected, in concord with the presumed dominant mode of transmission for FCHL. If the 95th percentile was used only 22% of study subjects were affected. To characterize the metabolic differences or similarities between the different lipid phenotypes, we determined very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) particles separated by ultracentrifugation. In linkage analysis no single ultracentrifugation variable could discriminate reliably affected family members from non-affected family members. Our data emphasizes the need for re-evaluation of FCHL diagnostic criteria. Preferably, the diagnosis should be based on a single, reliable metabolic marker.

Quantitative comparison of angiographic characteristics of coronary artery disease in patients with noninsulin-dependent diabetes mellitus compared with matched nondiabetic control subjects

The angiographic characteristics of coronary artery disease (CAD) in noninsulin-dependent diabetes mellitus (NIDDM) patients were studied by quantitative coronary angiography (QCA). Fifty-seven consecutive NIDDM patients undergoing clinically indicated elective coronary angiography and 57 nondiabetic coronary artery disease (CAD) patients were individually matched for sex, age, and body mass index. Technically adequate coronary angiograms, available for 55 subjects in each group, were analyzed with third-generation QCA software. To evaluate the anatomic severity and extent of CAD, several QCA-derived parameters were incorporated into indexes describing various per-patient features of CAD. These measures reflect CAD severity, extent, and overall "atheroma burden," and were calculated separately for different coronary segments (i.e., left main, proximal, mid, and distal segments), for the different coronary arterial territories (i.e., left main, left anterior descending, left circumflex, and right), and for the entire coronary tree. No significant differences were found between the NIDDM and nondiabetic groups (global severity index, 51 +/- 14 vs 54 +/- 13, p = NS; global extent index, 34 +/- 13 vs 32 +/- 12, p = NS; global atheroma burden index, 27 +/- 16 vs 24 +/- 12, p = NS). We also found no between-group differences in proximal, mid, or distal segments, in separate vessel territories, or in left ventricular function. Our data suggest that CAD patients, with and without NIDDM, who have similar symptoms at a given age, have similar severity and extent of CAD.

Determinants of postprandial lipemia in men with coronary artery disease and low levels of HDL cholesterol

We studied the determinants of postprandial lipemia in 49 post-coronary-bypass men with low HDL cholesterol (< or = 1.1 mmol/l at screening). The subjects were given a mixed meal containing 63 g fat and 150,000 IU vitamin A. Serum was obtained before and 3, 4, 5, 6, and 8 h after the meal. S(f) > 400 and S(f) 12-400 lipoproteins, LDL, and HDL were separated by ultracentrifugation; and triglyceride (TG), retinyl ester (RE), and apolipoprotein (apo)E concentrations were measured. The associations of 15 potential predictor variables with measures of postprandial lipemia were evaluated in univariate and multivariate models. Fasting TG concentration was the most important determinant of postprandial lipid and apoE concentrations. In univariate analyses, neither apoE phenotype nor common genetic polymorphisms in the apoB gene (XbaI and apoB signal peptide length polymorphisms), lipoprotein lipase gene (Hind III polymorphism), or apoC-III gene (C[1100] to T sequence change) significantly predicted the magnitude of postprandial lipemia. In multivariate linear regression analyses, fasting TG concentration (P< 0.001) and postheparin plasma hepatic lipase activity (P = 0.023) were directly, and body mass index (P = 0.007) and the presence of apoE2 (P = 0.029) allele inversely related to the TG increment in S(f) >400 lipoproteins. Fasting TG was associated with a high (P < 0.001) and presence of the SP24 allele of the apoB signal peptide gene with a low (P = 0.014) S(f) 12-400 TG response. Fasting TG concentrations alone predicted 35%, 10%, and 34% of the variability in postprandial S(f) >400 responses of TG, RE, and apoE; multivariate models improved this predictive power to 40-50%. Even multivariate models were poor predictors of postprandial responses in S(f) 12-400 lipoproteins (0-26%). Much of the interindividual variation in the magnitude of postprandial lipemia remained unexplained in the present study.

A study to determine the response of coronary atherosclerosis to raising low high density lipoprotein cholesterol with a fibric-acid derivative in men after coronary bypass surgery. The rationale, design, and baseline characteristics of the LOCAT Study. Lopid Coronary Angiography Trial

Several clinical trials have shown that reducing serum cholesterol levels retards the progression of coronary atherosclerosis assessed by serial angiography. By contrast, as yet no studies have addressed the impact of increasing high density lipoprotein (HDL) cholesterol levels on progression of coronary artery disease (CAD). As HDL cholesterol is inversely related to the risk of CAD, we hypothesize that an intervention that raises low HDL cholesterol concentrations may have a beneficial effect on the course of CAD. Lopid Coronary Angiography Trial (LOCAT) was designed to test this hypothesis. Three hundred and ninety-five men, aged < or = 70 years, all of whom had previously undergone coronary bypass surgery, were randomly assigned to receive either slow-release gemfibrozil, 1200 mg once daily, or a matching placebo for on average 2 1/2 years. The lipid inclusion criteria were HDL cholesterol concentration < or = 1.1 mmol/L, low density lipoprotein (LDL) cholesterol < or = 4.5 mmol/L, and serum triglyceride < or = 4.0 mmol/L. Subjects were not accepted if they had manifest diabetes, body mass index > 30 kg/m2, uncontrolled hypertension, or if they were regular smokers. All randomized subjects underwent baseline coronary angiography, which will be repeated at the end of the study. The angiograms will be analyzed using the Cardiovascular Measurement System, a validated computer-assisted image-analysis and quantitation package. The primary endpoints are the changes in the per-patient mean of 1) the average diameter of evaluable native coronary segments, and 2) the minimal luminal diameter of evaluable stenoses, and 3) the appearance of new lesions. Extensive lipoprotein and other metabolic studies and analyses of genetic polymorphisms are carried out to study the determinants of CAD progression. At baseline, the study subjects were 59.1 +/- 6.8 (mean +/- standard deviation) years old, had a body mass index 26.4 +/- 2.2 kg/m2, and serum triglyceride, serum cholesterol, HDL cholesterol, and LDL cholesterol concentrations 1.64 +/- 0.64, 5.17 +/- 0.64, 0.82 +/- 0.14, and 3.61 +/- 0.53 mmol/L, respectively.

Cholesterol efflux from Fu5AH hepatoma cells induced by plasma of subjects with or without coronary artery disease and non-insulin-dependent diabetes: importance of LpA-I:A-II particles and phospholipid transfer protein

We measured the capacity of human plasma to induce cholesterol efflux from Fu5AH rat hepatoma cells in four groups of men with or without non-insulin-dependent diabetes mellitus (NIDDM) and coronary artery disease (CAD). Plasma from men with both NIDDM and CAD (n = 47) had the lowest efflux capacity (17.3 +/- 3.6%) whereas healthy control subjects with neither diabetes nor CAD (n = 25) had the highest capacity (19.8 +/- 3.4%). The groups with CAD but no diabetes (n = 44) and with NIDDM but no CAD (n = 35) had intermediate efflux values (18.5 +/- 3.8 and 18.5 +/- 3.9%, respectively). In a 2 x 2 factorial ANOVA, the differences were significant with respect to the presence of CAD (P = 0.038) and NIDDM (P = 0.041), with no interaction between the factors. The concentration of HDL particles containing apolipoprotein (apo) A-I but no apo A-II (LpA-I) was not related to efflux capacity in univariate or multivariate analyses. A multivariate regression analysis showed that when controlled for the presence of NIDDM and CAD, the concentration of particles containing both apo A-I and apo A-II (LpA-I:A-II) and plasma phospholipid transfer protein activity were both positively, independently, and significantly (P < 0.001) related to cholesterol efflux capacity.

Influence of continued smoking and some biological risk factors on restenosis after percutaneous transluminal coronary angioplasty

OBJECTIVES

To identify possible biological risk factors for restenosis following successful percutaneous transluminal coronary angioplasty (PTCA) in patients having single or multivessel disease. The effect of continued smoking on restenosis was also evaluated.

DESIGN

In this prospective smoking controlled study all subjects had a routine angiographic restudy after 6 months. The biological risk factors assessed before angioplasty were adrenaline, endothelin, fibrinogen, lipoprotein (a) and tissue plasminogen activator.

SUBJECTS

The study population consisted of 122 patients of whom 25% were current smokers.

MAIN OUTCOME MEASURES

Angiographic restenosis was defined as at least 50% diameter stenosis on the follow-up angiogram after an initially successful procedure.

RESULTS

Restenosis was observed in 43% of patients. The restenosis rate was significantly lower among current smokers, but they were significantly younger and also had significantly less dilated stenoses. Multivariate analysis revealed the number of dilated stenoses, the mean inflation time, post-PTCA percentage diameter stenosis and left anterior descending coronary artery to be predictive of restenosis, while continued smoking was not. When only the lesion with the greatest loss in luminal diameter of each patient was considered, the multiple linear regression analysis revealed high endothelin level to be predictive of restenosis.

CONCLUSIONS

This study revealed high endothelin levels to be predictive of luminal narrowing after angioplasty. In addition, the number of dilated stenoses, the mean inflation time, post-PTCA percentage diameter stenosis and stenosis location in the left anterior descending artery were found to be predictive of restenosis. However, continued smoking after angioplasty did not emerge as a risk factor for restenosis.

The Gln-Arg191 polymorphism of the human paraoxonase gene (HUMPONA) is not associated with the risk of coronary artery disease in Finns

The human paraoxonase gene (HUMPONA) is codominantly expressed as alleles A and G. The A allele codes for glutamine (A genotype) and the G allele for arginine (B genotype) at position 191 of the paraoxonase enzyme. This genetic polymorphism has been suggested to be associated with the predisposition to coronary artery disease (CAD). We investigated the frequency of paraoxonase A and G alleles in 380 well-characterized CAD patients and in 169 controls. The most common genotype in both the patients with CAD (211/380) and in healthy Finnish individuals (87/169) was AA (Gln/Gln). The heterozygous AM (Gln/Arg) genotype was present in 140 of the patients and in 75 controls. The frequency of the A allele was 0.74 in both patients and controls. The genotype distribution between the two groups did not differ (P = 0.12, chi2 test). The genotype distributions were also similar to those reported earlier in other caucasoid populations. In conclusion, we found no association between the Gln-Arg 191 polymorphism of the human paraoxonase gene and coronary artery disease in Finns.

New insights into lipid metabolism in non-insulin-dependent diabetes mellitus

Perturbations of lipid metabolism are common in diabetes. Therefore, an understanding of the underlying mechanism of lipid metabolism and in particular the role of insulin is a critical issue. The review aims to provide evidence that hypertriglyceridaemia is central to many features of diabetic dyslipidaemia.

Heterozygosity for Asn291-->Ser mutation in the lipoprotein lipase gene in two Finnish pedigrees: effect of hyperinsulinemia on the expression of hypertriglyceridemia

We describe two Finnish kindreds with the Asn291 --> Ser mutation (A291S) of the lipoprotein lipase (LPL) gene. Sixteen subjects (9 male, 7 female) heterozygous for this mutation were studied and compared with 17 unaffected family members or spouses (family controls) and 19 unrelated healthy subjects (population controls). In the group of subjects heterozygous for the A291S mutation, postheparin plasma LPL activity was on average 23% lower than in the family controls and 29% lower than in the population controls. In agreement, in vitro expression studies with COS-7 cells showed that the mutant protein exhibits approximately 50% of the lipolytic activity of the wild-type protein. Median serum triglyceride concentration was 2.90 mmol/l in the group of heterozygotes, compared with 1.14 mmol/l in the family controls (P < 0.01) and 0.99 mmol/l in the population controls (P < 0.001). The heterozygotes also had a marked preponderance of small dense low density lipoproteins (LDL) as assessed by gradient gel electrophoresis. Nine of the heterozygous subjects were hypertriglyceridemic (serum triglyceride concentration > 2.0 mmol/l). Age or body mass index were not related to the presence of hypertriglyceridemia. By contrast, all hypertriglyceridemic subjects were either hyperinsulinemic (serum insulin concentration > 10 mU/l, n = 7) or had diabetes (n = 2). In a multivariate regression analysis, very low density lipoprotein (VLDL) triglyceride level was significantly and independently related to serum apolipoprotein B concentration, the presence of the A291S mutation, serum insulin concentration, and postheparin plasma LPL activity. The Asn291-->Ser mutation of the LPL gene results in reduced lipolytic activity. However, dyslipidemia appears to manifest only if VLDL production is also increased. Hyperinsulinemia was the major determinant of excessive VLDL synthesis and dyslipidemia among the subjects heterozygous for the A291S mutation in this study.

Regulation of low-density lipoprotein particle size distribution in NIDDM and coronary disease: importance of serum triglycerides

An increase of low-density lipoprotein triglycerides (LDL-Tg) was found to be an independent coronary artery disease (CAD) risk factor for non-insulin-dependent diabetic (NIDDM) patients in a recent prospective study. We examined the composition and size of LDL particles in 50 NIDDM men with angiographically verified CAD (NIDDM+ CAD+) and in 50 NIDDM men without CAD (NIDDM(+)-CAD-) as compared to 50 non-diabetic men with CAD (NIDDM - CAD +) and 31 non-diabetic men without CAD (NIDDM-CAD-). The groups had similar ranges of age and BMI. LDL particle size was determined by gradient gel electrophoresis, and LDL was isolated by sequential ultracentrifugation for compositional analyses. Serum Tg was increased in NIDDM patients as compared to non-diabetic subjects (p < 0.05), and in patients with CAD as compared to subjects without the disease (p < 0.05). LDL cholesterol was lower in NIDDM patients than in non-diabetic subjects (p < 0.001). Mean diameter of LDL particles was less than 255 A, but closely comparable in all groups. The presence of NIDDM was associated with increases of Tg and protein but lowering of free cholesterol in LDL (p < 0.005 for all). In multivariate regression analyses neither NIDDM nor CAD were associated with LDL particle size, but serum Tg was the major determinant of LDL size in both NIDDM and non-diabetic subjects (p < 0.001). When the patients were divided into quartiles according to fasting serum Tg levels, the LDL particle size and free cholesterol content decreased, but Tg and protein contents of LDL particles increased from the lowest to the highest Tg quartile (analysis of variance p < 0.001 for all). When the subjects were categorized into two groups according to the median of VLDL-Tg (1.10 mmol/l) LDL size was associated with VLDL-Tg in the high but not in the low VLDL-Tg group. We conclude that in NIDDM patients with or without CAD serum Tg is the major determinant of the properties of LDL particles. The clinical implication is that in NIDDM serum Tg should be as low as possible to prevent atherogenic changes in LDL.

Polymorphism of the glycogen synthase gene in hypertensive and normotensive subjects

Hypertension and non-insulin-dependent diabetes mellitus (NIDDM) are characterized by a strong genetic component and impaired ability to store glucose as glycogen in skeletal muscle. Impaired insulin activation and altered genetic control of muscle glycogen synthase, the rate-limiting enzyme for glucose storage in skeletal muscle, could provide an explanation for this insulin resistance. We examined whether there is an association between the glycogen synthase gene (Xba I polymorphism) and hypertension in 304 nondiabetic subjects. We examined glucose tolerance with an oral glucose tolerance test and glucose storage in skeletal muscle with the euglycemic insulin clamp technique in combination with indirect calorimetry. The Xba I A2 allele of the glycogen synthase gene was enriched in subjects with hypertension and a family history of NIDDM (48%) compared with normotensive subjects without a family history of NIDDM (6%, P < .0001). The presence of the A2 versus the A1 allele was associated with decreased rates of insulin-stimulated glucose storage in hypertensive subjects (11.2 +/- 2.3 versus 16.9 +/- 2.6 mumol/kg lean body mass per minute, P = .029) but not in normotensive subjects (28.0 +/- 4.6 versus 29.6 +/- 3.7 mumol/kg lean body mass per minute). In conclusion, Xba I polymorphism of the glycogen synthase gene identifies a subgroup of hypertensive subjects with a family history of NIDDM. The data suggest that a locus in the glycogen synthase gene region on chromosome 19 may serve as a "thrifty gene," increasing susceptibility for insulin resistance when exposed to other environmental or genetic factors.

HDLs containing apolipoproteins A-I and A-II (LpA-I:A-II) as markers of coronary artery disease in men with non-insulin-dependent diabetes mellitus

BACKGROUND

Abnormalities in HDL and an increased risk of coronary artery disease (CAD) coexist in non-insulin-dependent diabetes mellitus (NIDDM). HDLs can be separated by their apolipoprotein (apo) content into particles containing apoA-I but not apoA-II (LpA-I) and those containing both apoA-I and apoA-II (LpA-I:A-II). The LpA-I particles have been suggested to be more effective in conferring protection against CAD than the LpA-I:A-II particles. However, data are sparse, and no studies have defined the role of these two classes of particles in NIDDM.

METHODS AND RESULTS

LpA-I and LpA-I:A-II particles were quantified by a differential electroimmunoassay in four groups of men with similar age and body mass index (BMI) distributions. Group 1 consisted of 50 patients with NIDDM and angiographically verified CAD; group 2, 50 men with CAD but no diabetes; group 3, 50 men with NIDDM but no CAD; and group 4, 31 healthy men. Serum apoA-I and apoA-II concentrations were measured by immunoturbidimetry, and HDL2 and HDL3 were separated by ultracentrifugation. Concentrations of LpA-I:A-II particles in group 1 were 13.8%, 18.3%, and 26.9% lower than in groups 2 through 4, respectively. In a two-by-two factorial ANOVA, adjusted for age and BMI, the differences were significant for both CAD (P < .001) and NIDDM (P < .001), with no interaction between the factors. These results were confirmed by comparable differences in the serum concentrations of apoA-I and apoA-II. LpA-I particles were related to the presence or absence of CAD (P = .013), but the difference was lost in a multivariate analysis. A low HDL3 cholesterol concentration characterized both CAD (P = .002) and NIDDM (P = .024). HDL2 cholesterol differed significantly with regard to the presence of NIDDM (P = .033) but only borderline with respect to CAD (P = .073).

CONCLUSIONS

ApoA-II-containing lipoproteins and HDL3 cholesterol are powerful markers of CAD in men with NIDDM.

High density lipoprotein subfractions in non-insulin-dependent diabetes mellitus and coronary artery disease

High density lipoprotein (HDL) subfractions (2b, 2a, 3a, 3b, and 3c) separated by gradient gel electrophoresis (GGE) and defined by Gaussian summation analysis, and the compositions of HDL2 and HDL3, separated by preparative ultracentrifugation, were studied in four groups of men with or without non-insulin-dependent diabetes mellitus (NIDDM) and coronary artery disease (CAD): group 1 (DM+CAD+, n = 50); group 2 (DM-CAD+, n = 50); group 3 (DM+CAD-, n = 50); and group 4 (DM-CAD-, n = 31). HDL GGE subfraction distributions, available in 125 subjects, were not significantly different among the groups. In contrast, dividing the whole study population into quartiles of serum triglyceride (TG) concentration showed that high TG levels were significantly associated with low HDL2b and high HDL3b concentrations. In a multivariate linear regression model, postheparin plasma hepatic lipase (HL) activity, and fasting serum insulin and TG concentrations were all associated independently and inversely with low HDL2b, but lipoprotein lipase or cholesteryl ester transfer protein activities were not correlated with HDL2b concentrations. Group 1 tended to have the smallest mean particle sizes in the HDL subfractions, significantly (P < 0.03, CAD vs. non-CAD) for HDL2b and for HDL2a. These differences were independent of TG, insulin and HL, but lost their significance when adjusted for beta-blocker therapy. Both HDL2 and HDL3 particles in group 1 were significantly depleted of unesterified cholesterol, and their HDL2 was TG-enriched (P = 0.053). A high HL activity, hyperinsulinemia and hypertriglyceridemia are independently associated with low levels of HDL2b and generally small HDL particle size. HDL particles in subjects with NIDDM and CAD are small-sized and have a low free cholesterol content. Both these characteristics may be markers of impaired reverse cholesterol transport.

Accuracy and precision of quantitative arteriography in the evaluation of coronary artery disease after coronary bypass surgery. A validation study

Computer-assisted quantitative coronary arteriography (QCA) has gained widespread acceptance in assessing changes in coronary dimensions over time, but little is known about the utility of QCA in patients having undergone coronary bypass surgery. As a validation study, we analyzed the accuracy and precision of QCA in a subset of the baseline angiograms of a clinical trial in 395 post-bypass men with low HDL cholesterol concentrations who have been randomized to receive double-blind gemfibrozil or placebo for 2 1/2 years. Based on repeat measurements of the same cineframe, the average diameter of a segment (ADS) had a mean coefficient of variation (CV) of 3.1%. The mean CVs of the minimum luminal diameter (MLD), percent diameter stenosis (PDS) and stenotic flow reserve of an obstruction were 8.6, 10.2 and 9.8%, respectively, but the area of the atherosclerotic plaque had an unacceptably high CV, 24.0%. When the measurements from two contrast injections into a native coronary artery during the same angiographic session were compared, precision (standard deviation of the differences) was 0.198 mm for ADS, 0.192 mm for MLD, and 7.37% for PDS. Variability was not substantially reduced when measurements from 3 or 5 consecutive cineframes were averaged. Comparable repeatability was found when venous bypass grafts were imaged twice, whether the grafts themselves or the grafted native vessels were analyzed. We conclude that QCA has an acceptable accuracy and precision in analyzing coronary dimensions in bypass-grafted patients. A change of 0.40 mm in ADS and MLD, and 20% in PDS represent true progression or regression of coronary atherosclerosis with more than 95% confidence.

Plasma cholesteryl ester transfer protein activity in non-insulin-dependent diabetic patients with and without coronary artery disease

The present study was designed to evaluate the potential role of plasma cholesteryl ester transfer protein (CETP) activity in the regulation of high-density lipoprotein (HDL) subclasses in non-insulin-dependent diabetes mellitus (NIDDM). We studied 45 men with NIDDM and angiographically defined coronary artery disease ([CAD] DM+CAD+, aged 54.4 +/- 6.1 years, mean +/- SD); 47 nondiabetic men with similarly proven CAD (DM-CAD+, aged 54.9 +/- 6.6 years; 43 men with NIDDM but no CAD (DM+CAD-, aged 55.2 +/- 7.3 years); and 29 nondiabetic men without CAD (DM-CAD-, aged 53.2 +/- 5.3 years). The groups were matched for age and body mass index (BMI). Plasma CETP activity was determined by measuring the ability of the plasma sample to transfer esterified cholesterol from exogenous 14C-cholesteryl ester-labeled low-density lipoprotein (LDL) to exogenous HDL. Plasma lipoproteins were separated by ultracentrifugation. The concentration of HDL cholesterol was reduced in the DM+CAD+ group as compared with the DM-CAD- group (P < .01). This change was due to a decrease of both HDL2 cholesterol (P < .05) and HDL3 cholesterol (P < .001). There was a clear-cut decrease in HDL3 cholesterol in the DM-CAD+ (P < .01) and DM+CAD- (P < .05) groups as compared with the DM-CAD- group. Plasma CETP activity was lower in the DM+CAD- group (1.06 +/- 0.24 arbitrary units [AU]) than in the DM-CAD- group (1.19 +/- 0.26 AU, P < .05). In the DM+CAD+ group, the mean of CETP activities was 1.09 AU.(ABSTRACT TRUNCATED AT 250 WORDS)

Enrichment with apolipoprotein E characterizes postprandial TG-rich lipoproteins in patients with non-insulin-dependent diabetes mellitus and coronary artery disease: a preliminary report

An oral fat-load test was carried out in patients with non-insulin-dependent diabetes mellitus (NIDDM) and angiographically verified coronary artery disease (CAD; group 1, n = 6); in patients with CAD but no diabetes (group 2, n = 6); in patients with NIDDM but no CAD (group 3, n = 4); and in healthy control subjects (group 4, n = 4). Concentrations of apolipoprotein (apo) E, apo C-II, triglyceride (TG), retinyl palmitate, and cholesterol were measured in fasting plasma and in plasma obtained after 2, 4, 6, 9, and 24 h after a meal containing 78 g of fat and 345,000 IU of vitamin A. The same measurements were carried out in the lipoprotein fractions with Svedberg flotation rates Sf 400-1100, 60-400, 20-60 and 12-20, obtained by density gradient ultracentrifugation. The postprandial apo E concentrations were highest in group 1 (NIDDM and CAD) in plasma and in the TG-rich lipoprotein fractions, with significant differences in comparison with the healthy subjects. As shown by apo E to TG ratios, the postprandial lipoproteins were enriched with apo E in the patients with NIDDM and CAD. The largest excesses of apo E in group 1 patients were observed in the atherogenic Sf 12-60 lipoproteins. Across the entire study population, there was a significant inverse correlation between the postprandial apo E responses and the postheparin lipoprotein lipase activity. The results suggest that enrichment of the remnant lipoproteins with apo E may have a role in the increased risk of CAD among patients with NIDDM.

Abnormal metabolism of postprandial lipoproteins in patients with non-insulin-dependent diabetes mellitus is not related to coronary artery disease

To investigate whether abnormalities in alimentary lipemia explain the increased risk of coronary artery disease (CAD) in subjects with non-insulin-dependent diabetes mellitus (NIDDM), we performed an oral vitamin A fat-load test in four groups of men (each n = 15): 1) NIDDM and angiographically verified CAD (DM+CAD+): 2) CAD but no diabetes (DM-CAD+); 3) NIDDM but no CAD, excluded by an exercise thallium scan (DM+CAD-); and 4) healthy control subjects (DM-CAD-). The groups were matched for age and body mass index. Plasma obtained after an overnight fast and 2, 3, 4, 6, 9, 12, and 24 h after a fatty meal (78 g fat, 345,000 IU retinyl palmitate [RP]) was separated by density gradient ultracentrifugation into six fractions of triglyceride (TG)-rich lipoproteins: Svedberg flotation units (Sf) > 3200, Sf 1100-3200, Sf 400-1100, Sf 60-400, Sf 20-60, and Sf 12-20. TG, RP, and cholesterol concentrations were measured in plasma and in each lipoprotein fraction. Postprandial plasma TG responses were significantly larger in both NIDDM groups than in the healthy control group. The most marked differences were observed in the Sf 60-400 lipoproteins, whether measured as TG or RP responses. However, there were no differences between the DM+CAD+ and DM+CAD- groups. The between-group differences in alimentary lipemia were only partially explained by fasting TG levels. In contrast to the healthy subjects, no significant negative correlation was observed in the NIDDM patients between alimentary lipemia and lipoprotein lipase activity, implying an abnormality of the lipolysis of TG-rich particles in NIDDM. Levels of atherogenic postprandial remnant lipoproteins are increased in NIDDM. However, in this study the magnitude of alimentary lipemia did not distinguish NIDDM patients with CAD from those without CAD symptoms and normal exercise thallium scans.