Effect of folic acid and antioxidant vitamins on endothelial dysfunction in patients with coronary artery disease.

OBJECTIVES: The purpose of this study was to determine whether lowering homocysteine levels with folic acid, with or without antioxidants, will improve endothelial dysfunction in patients with coronary artery disease (CAD). BACKGROUND: Elevated plasma homocysteine levels are a risk factor for atherosclerosis. Homocysteine may promote atherogenesis through endothelial dysfunction and oxidative stress. METHODS: In a double-blind, placebo-controlled, randomized trial, we used vascular ultrasound to assess the effect of folic acid alone or with antioxidants on brachial artery endothelium-dependent flow-mediated dilation (FMD). Seventy-five patients with CAD (screening homocysteine level > or =9 micromol/liter) were randomized equally to one of three groups: placebo, folic acid alone or folic acid plus antioxidant vitamins C and E. Patients were treated for four months. Plasma folate, homocysteine, FMD and nitroglycerin-mediated dilation were measured before and after four months of treatment. RESULTS: Plasma folate, homocysteine and FMD were unchanged in the placebo group. Compared with placebo, folic acid alone increased plasma folate by 475% (p < 0.001), reduced plasma homocysteine by 11% (p = 0.23) and significantly improved FMD from 3.2 +/- 3.6% to 5.2 +/- 3.9% (p = 0.04). The improvement in FMD correlated with the reduction in homocysteine (r = 0.5, p = 0.01). Folic acid plus antioxidants increased plasma folate by 438% (p < 0.001), reduced plasma homocysteine by 9% (p = 0.56) and insignificantly improved FMD from 2.6 +/- 2.4% to 4.0 +/- 3.7% (p = 0.45), as compared with placebo. Nitroglycerin-mediated dilation did not change significantly in any group. CONCLUSIONS: Folic acid supplementation significantly improved endothelial dysfunction in patients with coronary atherosclerosis. Further clinical trials are required to determine whether folic acid supplementation may reduce cardiovascular events.

Plasma homocyst(e)ine levels in men with premature coronary artery disease.

Plasma homocyst(e)ine (that is, the sum of free and bound homocysteine and its oxidized forms, homocystine and homocysteine-cysteine mixed disulfide) levels were determined in 170 men (mean age +/- SD 50 +/- 7 years) with premature coronary artery disease diagnosed at coronary angiography and in 255 control subjects clinically free of coronary artery disease (mean age 49 +/- 6 years). Patients with coronary artery disease had a higher homocyst(e)ine level than control subjects (13.66 +/- 6.44 versus 10.93 +/- 4.92 nmol/ml, p less than 0.001). High density lipoprotein (HDL) cholesterol levels were lower (32 +/- 10 versus 46 +/- 13 mg/dl, p less than 0.001) and triglycerides levels were higher (193 +/- 103 versus 136 +/- 106 mg/dl, p less than 0.001) in the coronary disease group. Plasma total cholesterol and low density lipoprotein (LDL) cholesterol levels were not significantly different between patients with coronary disease and control subjects. The presence of hypertension, smoking or diabetes mellitus did not significantly alter homocyst(e)ine levels in the patient or the control group. Patients who were not taking a beta-adrenergic blocking drug (n = 70) had a nonsignificantly higher homocyst(e)ine level than did patients taking this class of drugs (n = 100) (14.67 +/- 8.92 versus 12.95 +/- 3.77 nmol/ml, p = 0.087). By design, none of the control subjects were taking a beta-blocker. No significant correlations were observed between homocyst(e)ine and age, serum cholesterol, LDL cholesterol, HDL cholesterol or triglyceride levels. It is concluded that an elevated plasma homocyst(e)ine level is an independent risk factor for the development of premature coronary atherosclerosis in men.

Familial lipoprotein disorders and premature coronary artery disease.

Significant risk factors for premature coronary heart disease include: (1) family history, (2) elevated low density lipoprotein (LDL) cholesterol level > or = 160 mg/dl, l, (3) decreased high density lipoprotein (HDL) cholesterol level < 35 mg/dl, l, (4) cigarette smoking, (5) high blood pressure and (6) diabetes mellitus. All of these risk factors are common in patients with premature heart disease. Common familial lipid disorders associated with premature heart disease include familial lipoprotein(a) excess, familial dyslipidemia (elevated triglycerides and decreased HDL cholesterol), familial combined hyperlipidemia (elevations of LDL cholesterol and triglycerides, and often decreased HDL cholesterol), familial hypoapobetalipoproteinemia (elevated apolipoprotein B levels), familial hypoalphalipoproteinemia (low HDL cholesterol levels), and familial hypercholesterolemia (elevated LDL cholesterol levels). All these disorders have been characterized using age and gender specific 90th and 10th percentile values from the normal population. The diagnosis and potential management of these disorders is reviewed.

Plasma apolipoprotein A-I, A-II, B, E and C-III containing particles in men with premature coronary artery disease.

Lipoprotein (Lp) cholesterol and apolipoproteins (apo) A-I and B levels have been shown to be better markers for the presence of coronary artery disease than total cholesterol. In this study, we determined the plasma levels of lipoprotein particles containing apo A-I only (LpA-I), apo A-I and A-II (LpA-I:A-II), apo B and C-III (LpB:C-III) and apo B and E (LpB:E) in 145 patients with coronary artery disease (mean age +/- SD, 51 +/- 7 years) and 135 healthy control men (mean age 49 +/- 11 years). Patients with CAD had lower high density lipoprotein (HDL) cholesterol and apo A-I levels and higher triglycerides and apo had lower high density lipoprotein (HDL) cholesterol and apo A-I levels and higher triglycerides and apo B levels than controls. In patients with CAD, LpA-I (0.341 +/- 0.093 vs. 0.461 +/- 148 g/l) and LpA-I:A-II (0.694 +/- 0.171 vs. 0.899 +/- 0.148 g/l) were lower, whereas LpB:E (0.372 +/- 0.204 vs. 0.235 +/- 0.184 g/l) were higher than in controls (cases vs. controls, all P less than 0.005). No significant differences were observed for LpB:C-III (0.098 +/- 0.057 vs. 0.107 +/- 0.061 g/l, p = 0.235) particles. Discriminant analysis indicates that LpA-II:A-I, LpE:B, LpA-I, and triglycerides best differentiate between cases and controls. Plasma apo C-III (0.027 +/- 0.008 vs. 0.036 +/- 0.020 g/l) and E (0.040 +/- 0.015 vs. 0.055 +/- 0.029 g/l) were lower in the CAD group (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

DNA polymorphisms of the apolipoprotein B gene in patients with premature coronary artery disease.

Elevated plasma levels of low density cholesterol and their major apolipoprotein (apo B) are associated with an increased risk of coronary artery disease (CAD). We have examined allele frequencies of restriction fragment length polymorphisms (RFLP) of the apo B gene in 111 male Caucasians with premature CAD (mean age 49 +/- 7 years) and in 122 elderly Caucasian males (mean age, 73 +/- 5 years), free of clinical cardiovascular disease. The rare allele (R1) of the EcoR1 RFLP in exon 29, resulting in an amino acid change (Glu----Lys4154) was seen more frequently in CAD than in controls (0.270 vs 0.207, P less than 0.05). The R1 RFLP and the MspI insertion polymorphisms (MI) within the 3' hypervariable region (HVR) were observed together in 87% and are likely in linkage disequilibrium. The MI RFLP were slightly more frequent in CAD than control (0.239 vs. 0.211, P = 0.08). A second MspI RFLP in exon 26 results in an amino acid change (Arg----Glu3611); the rare allele M2 was seen more frequently in patients than in controls (0.150 vs. 0.057, P less than 0.005). No significant differences in allele frequencies were observed for the Xba1 RFLP in exon 26 (0.500 vs. 0.529, P = ns) or for the PvuII RFLP near the 5' end (P2) (0.105 vs. 0.088, P = ns). No statistically significant differences in lipid, lipoprotein cholesterol or apolipoproteins A-I and B were observed in patients or in controls. Two of the RFLPs examined (R1 and M2) result in changes in amino acid sequence and their allele frequencies are increased in CAD cases when compared with controls. Genetic variability within the apo B gene may thus contribute to cardiovascular risk. The physiological effects of individual mutations within apo B remain to be determined. It is unlikely, however that the single site polymorphisms examined in this study, will impart further information about CAD risk than conventional lipid parameters.

Prevalence of risk factors in men with premature coronary artery disease.

The prevalence of modifiable cardiovascular risk factors (systemic hypertension, diabetes mellitus, cigarette smoking, low-density lipoprotein [LDL] cholesterol greater than or equal to 160 mg/dl and high-density lipoprotein [HDL] cholesterol less than 35 mg/dl) was determined in 321 men less than 60 years of age (mean +/- standard deviation 50 +/- 7) with premature coronary artery disease (CAD) documented at coronary angiography. The prevalence of these risk factors was markedly different than in the Framingham Offspring Study population, used here as a comparison group. In the patients with CAD, only 3% had no risk factor (other than male sex), compared with 31% in the Framingham Offspring Study subjects. Most patients with CAD (97%) had greater than or equal to 1 additional risk factor. When the patients with CAD were divided by age groups (40 to 49 years [n = 109], 50 to 59 [n = 191]), no significant differences were observed in the prevalence of risk factors between the young and older patients. The prevalence of systemic hypertension (41 vs 19%, p less than 0.001), diabetes mellitus (12 vs 1.1%, p less than 0.001), cigarette smoking (67 vs 28%, p less than 0.001) and HDL cholesterol less than 35 mg/dl (63 vs 19%, p less than 0.001) was markedly higher in the patients with CAD than in Framingham Offspring Study subjects, whereas the prevalence of LDL cholesterol greater than or equal to 160 mg/dl was not significantly different between patients with CAD and Framingham Offspring Study subjects (26 vs 26%).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hospitalization on high-density lipoprotein cholesterol in patients undergoing elective coronary angiography.

The effects of time of sampling on plasma lipids and lipoprotein cholesterol concentrations were investigated in 88 patients undergoing elective coronary angiography. Patients with a myocardial infarction or major surgery within 6 weeks before catheterization were excluded. All subjects were sampled in the fasting state at the time of arteriotomy before systemic heparinization and at least 30 days after discharge from the hospital (mean 275 days) in the free living state. No statistically significant differences were noted in total cholesterol (220 +/- 51 vs 226 +/- 48 mg/dl), triglycerides (191 +/- 77 vs 191 +/- 113 mg/dl) and calculated low-density lipoprotein cholesterol levels (149 +/- 46 vs 150 +/- 43 mg/dl). High-density lipoprotein cholesterol values were significantly lower (p less than 0.0001) in subjects sampled before catheterization than in the free living state (32 +/- 10 vs 37 +/- 10 mg/dl, mean change 14%). Moreover, the frequency of high-density lipoprotein cholesterol less than 35 mg/dl was 77% before catheterization and 44% in the free living state. This effect was neither due to beta-adrenergic drugs nor to the length of time between samplings. In view of these findings, a screening lipid profile for patients with coronary artery disease should be performed in the free living state.

Low density lipoprotein particle size and coronary artery disease.

Decreased plasma low density lipoprotein (LDL) particle size has been associated with premature coronary artery disease (CAD). We examined LDL particle size by 2-16% gradient gel electrophoresis in 275 men with CAD (greater than 75% cross-sectional-area stenosis) and 822 controls. Seven major LDL size bands (with LDL-1 [d = 1.025-1.033 g/ml] being the largest and LDL-7 [d = 1.050-1.063 g/ml, the smallest]) were identified. Because most subjects had two or more adjacent LDL bands, an LDL score was calculated for each subject, with the relative area in each band taken into consideration. Four major LDL particle size groups were classified in the present studies: large LDL, intermediate LDL, small LDL, and very small LDL. The use of beta-blockers was significantly associated with smaller LDL particles. After adjusting for use of this medication, small LDL particles were still more prevalent in CAD patients (39%) compared with controls (27%). The prevalence of large LDL particles was lower in CAD patients (3%) than in controls (24%). Intermediate LDL particles were the most prevalent in both groups, 49% in CAD patients and 46% in controls. The difference in LDL particle size between CAD patients and controls was not independent but was highly associated (p less than 0.0001) with elevated triglyceride levels and decreased high density lipoprotein (HDL) cholesterol levels. Significantly higher LDL cholesterol levels were found in subjects with intermediate and small LDL particles than in those with large or very small LDL particles.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of familial hyperhomocyst(e)inemia in men with premature coronary artery disease.

Elevated plasma levels of homocyst(e)ine have been reported to be more prevalent in patients with coronary artery disease (CAD) than in controls. The purpose of this study was to determine whether this elevation was genetic. We determined homocyst(e)ine levels in 176 men with premature CAD (greater than 50% stenosis of a major epicardial coronary artery occurring before the age of 60 years) and in 255 controls free of cardiovascular disease. Homocyst(e)ine levels were higher in the CAD group compared with controls (13.9 +/- 6.7 versus 10.9 +/- 4.9 nmol/ml, p less than 0.001); in addition, 28% of CAD patients had homocyst(e)ine levels above the 90th percentile of controls. Statistical analysis revealed that homocyst(e)ine levels were not related to the presence of hypertension or diabetes, smoking, or plasma levels of lipoprotein cholesterol and apolipoproteins A-I and B. The families of 71 CAD patients were sampled (selected on the basis of availability of relatives) and included 60 spouses and 239 first-degree relatives; 370 subjects were thus sampled. Spearman correlations between probands and spouses (r = 0.264, p = 0.041) and between mean values for parent and offspring (r = 0.356, p = 0.002) for homocyst(e)ine levels indicated that homocyst(e)ine levels are in part genetically determined. In 20 families (28.2%), the proband had homocyst(e)ine levels greater than the 90th percentile; familial segregation was observed in 10 of these kindreds. Therefore, 14% of CAD patients had familial hyperhomocyst(e)inemia. In conclusion, our data suggest that plasma homocyst(e)ine is a risk factor for the development of CAD, independent of other cardiovascular risk factors, and that this elevation is in part genetically determined.

Familial lipoprotein disorders in patients with premature coronary artery disease.

BACKGROUND: Genetic lipoprotein disorders have been associated with premature coronary artery disease (CAD). METHODS AND RESULTS: The prevalence of such disorders was determined in 102 kindreds (n = 603 subjects) in whom the proband had significant CAD documented by angiography before the age of 60 years. Fasting plasma cholesterol, triglyceride, low density lipoprotein (LDL) cholesterol, apolipoprotein (apo) B, and lipoprotein (a) [Lp(a)] values above the 90th percentile and high density lipoprotein (HDL) cholesterol and apo A-I below the 10th percentile of age- and sex-specific norms were defined as abnormal. An abnormality was noted in 73.5% of probands compared with 38.2% in age-matched controls (p less than 0.001), with a low HDL cholesterol level (hypoalphalipoproteinemia) being the most common abnormality (39.2% of cases). In these kindreds, 54% had a defined phenotypic familial lipoprotein or apolipoprotein disorder. The following frequencies were observed: Lp(a) excess, 18.6% (includes 12.7% with no other dyslipidemias); hypertriglyceridemia with hypoalphalipoproteinemia, 14.7%; combined hyperlipidemia, 13.7% (11.7% with and 2.0% without hypoalphalipoproteinemia); hyperapobetalipoproteinemia (elevated apo B only), 5%; hypoalphalipoproteinemia, 4%; hypercholesterolemia (elevated LDL only), 3%; hypertriglyceridemia, 1%; decreased apo A-I only, 1%. Overall, 54% of the probands had a familial dyslipidemia; unclassifiable lipid disorders (spouse also affected) were found in 3%. No identifiable familial dyslipidemia was noted in 43% of kindreds of those; nearly half (45%) had a sporadic lipid disorder. Parent-offspring and proband-spouse correlations for these biochemical variables revealed that lipoprotein and apolipoprotein levels are in part genetically determined, with Lp(a) showing the highest degree of parent-offspring correlation. CONCLUSIONS: Our data indicate that more than half of patients with premature CAD have a familial lipoprotein disorder, with Lp(a) excess, hypertriglyceridemia with hypoalphalipoproteinemia, and combined hyperlipidemia with hypoalphalipoproteinemia being the most common abnormalities.