Hyperhomocysteinaemia and premature coronary artery disease in the Chinese

Association between Hyperhomocysteinemia and Hypertensive Retinopathy in a Chinese Han Population

Purpose/aim: In some diseases, hyperhomocysteinemia (HHcy) has been recognized as a risk factor. However, information on the correlation between HHcy and hypertensive retinopathy (HR) in the Chinese population is unclear. We, therefore, aimed to investigate this association.Materials and Methods: A total of 382 patients were collected and 126 individuals were excluded in this study. Finally, 128 patients with HR and 128 control subjects were enrolled sequentially. The association between HHcy and the occurrence of HR was determined by multivariate logistic regression analysis, including interaction and stratified analyses.Results: HHcy, cardiovascular disease, fasting blood glucose, creatinine, triglyceride, diabetes, smoking habits, drinking habits were significantly associated with HR (P < .05) in the univariate logistic regression analysis. Each increase of 1 μmol/L of homocysteine concentration was significantly correlated with a 9% increased risk of HR (odds ratio [OR] = 1.09, 95% confidence interval [CI]: 1.07-1.55, P < .05). Hierarchical analysis identified history of diabetes (OR = 7.38, P > .05), age ≥60 years (OR = 3.08, P > .05), male sex (OR = 1.04, P > .05), history of cardiovascular disease (OR = 7.88, P > .05), smoking habit (OR = 1.08, P > .05), and drinking habit (OR = 78.31, P > .05), as factors associated with HR, but not as independent risk factors for HR. Interaction analysis demonstrated no interaction between HHcy and HR.Conclusions: Within the Chinese Han population, HHcy is an independent risk factor for HR.

Cigarette smoking reduced renal function deterioration in hypertensive patients may be mediated by elevated homocysteine

Elevated homocysteine (HCY) and smoking are both important risk factors for hypertensive patients. However, whether they have crossing effect on renal function deterioration of hypertensive patients and what is the underlying mechanism are unclear. In the present study, 3033 participants diagnosed as essential hypertension with estimated glomerular filtration rate (eGFR)> 30 ml/min/1.73 m² from southern China were enrolled in this cross-sectional study. We collected the demographic and clinical data. In addition, the mediation effects were analyzed. The results showed that, comparing with non-smokers, smokers had significant higher levels of HCY (13.10 (11.20−16.87) vs. 11.00 (8.90−13.40) umol/L, P < 0.001) and lower eGFR (79.71 (66.83−91.05) vs. 82.89 (69.80−95.85) ml/min/1.73m², P < 0.001). HCY levels and smoking were independently associated with decreased eGFR. Meanwhile, eGFR levels were significantly negatively correlated with HCY (P < 0.001), and this correlation might be stronger in current smokers. Current smoker consuming over 20 cigarettes per day would accelerate early renal function deterioration (OR = 1.859, P = 0.019). The mediation effects analysis further showed that the association between smoking and renal function deterioration was mediated by HCY. And elevated HCY was accounted for 56.94% of the estimated causal effect of smoking on renal function deterioration in hypertensive patients. Our findings indicated that cigarette smoking was associated with renal function deterioration in hypertensive patients, and the association between cigarette smoking and renal function deterioration was probably mediated by elevated HCY. Therefore, HCY-lowering therapy may be beneficial for renal function deterioration in hypertensive smoking patients.

Possible ethnic differences in plasma homocysteine levels associated with coronary artery disease between south Asian and east Asian immigrants

BACKGROUND

Hyperhomocysteinemia has been identified as a risk factor for coronary artery disease (CAD). South Asians appear to have a high incidence of CAD, while East Asians have a very low incidence.

HYPOTHESIS

The present study was undertaken because the relative association of plasma homocysteine levels (PH) with CAD in South Asians (SA = Indian, Pakistani, Sri Lankan) and East Asians (EA = Chinese, Japanese) is not known.

METHODS

Fasting PH were drawn on all patients with CAD of SA (age 62.4+/-1.1 years, 72 men, 14 women) and EA (age 61.8+/-3.0 years, 13 men, 4 women) descent. These were compared with PH available from Caucasian (CA) patients (age 61.1+/-1.1 years, 89 men, 17 women) with CAD.

RESULTS

The PH in SA, EA, and CA patients were 11.0+/-0.5, 7.6+/-0.5, and 10.8+/-0.6 micromol/l, respectively (p<0.001 between EA and SA/CA). Percentages of SA, EA, and CA with elevated PH (> 12.0 micromol/l) were 33.7, 5.9, and 28.2%, respectively. There were no significant differences in the lipid subfractions between the SA and EA group. History of smoking was significantly higher in the EA (52.9 vs. 26.2%), while hypertension and diabetes mellitus had similar prevalences.

CONCLUSION

Significant differences in PH of SA versus EA patients with CAD exist. The relative contribution of homocysteine in the development of CAD appears to be less in EA immigrants. In contrast, the association between CAD and PH in SA immigrants appears to be similar to that of Caucasians.

Effect of homocysteine on nitric oxide production in coronary microvascular endothelial cells

Hyperhomocysteinemia is widely recognized as an independent risk factor for coronary artery vascular disease, although the underlying mechanisms are not well understood. This study aims to investigate the effect of homocysteine on nitric oxide (NO) production in coronary microvascular endothelial cells (CMECs) and putative mechanisms mediating this effect. CMECs were isolated on Langendorff system by collagenase perfusion of hearts from male rats and cultured. The effect of homocysteine (0.01 to 1 mM) on basal and stimulated NO production was evaluated by measuring nitrite in the culture media after incubation with or without N(G)-nitro-L-arginine methyl ester (L-NAME) (1 mM), superoxide dismutase (100 U/mL), or catalase (1000 U/mL) for 24 h. Total nitrite was measured using Griess reaction after reduction of nitrate to nitrite with nitrate reductase. Homocysteine did not affect basal nitrite accumulation; however, it significantly increased the nitrite accumulation induced by the calcium ionophore A23187 or interleukin-1beta only at 1 mM. This effect of homocysteine was significantly inhibited by L-NAME, superoxide dismutase, and catalase. In conclusion, homocysteine increases NO release from stimulated CMECs without affecting basal NO production, which is probably accompanied by increased production of reactive oxygen species. It can be postulated that endothelial cells generate NO in order to minimize the damage caused by homocysteine.

Homocysteine, vitamin B12 and folate levels in premature coronary artery disease

BACKGROUND

Hyperhomocysteinemia is known as an independent risk factor of atherosclerosis, but the probable role of hyperhomocysteinemia in premature Coronary Artery Disease (CAD) is not well studied. The aim of this study was to assess the role of hyperhomocysteinemia, folate and Vitamin B12 deficiency in the development of premature CAD.

METHODS

We performed an analytical case-control study on 294 individuals under 45 years (225 males and 69 females) who were admitted for selective coronary angiography to two centers in Tehran.

RESULTS

After considering the exclusion criteria, a total number of 225 individuals were enrolled of which 43.1% had CAD. The mean age of participants was 39.9 +/- 4.3 years (40.1 +/- 4.2 years in males and 39.4 +/- 4.8 years in females). Compared to the control group, the level of homocysteine measured in the plasma of the male participants was significantly high (14.9 +/- 1.2 versus 20.3 +/- 1.9 micromol/lit, P = 0.01). However there was no significant difference in homocysteine level of females with and without CAD (11.8 +/- 1.3 versus 11.5 +/- 1.1 micromol/lit, P = 0.87). Mean plasma level of folic acid and vitamin B12 in the study group were 6.3 +/- 0.2 and 282.5 +/- 9.1 respectively. Based on these findings, 10.7% of the study group had folate deficiency while 26.6% had Vitamin B12 deficiency. Logistic regression analysis for evaluating independent CAD risk factors showed hyperhomocysteinemia as an independent risk factor for premature CAD in males (OR = 2.54 0.95% CI 1.23 to 5.22, P = 0.01). Study for the underlying causes of hyperhomocysteinemia showed that male gender and Vitamin B12 deficiency had significant influence on incidence of hyperhomocysteinemia.

CONCLUSION

We may conclude that hyperhomocysteinemia is an independent risk factor for CAD in young patients (below 45 years old)--especially in men--and vitamin B12 deficiency is a preventable cause of hyperhomocysteinemia.

Job stress and cardiovascular risk factors in male workers

BACKGROUND

This study examined whether job stress (work demand and decision latitude) is associated with smoking, blood pressure, lipid level (total cholesterol, triglyceride, HDL cholesterol), and homocystein as risk factors for cardiovascular disease in Korean male workers.

METHODS

Study subjects of this study were recruited from a sample of 1,071 workers in 20 companies of W city and H counties, and they were grouped into four categories (high strain group, active group, passive group, and low strain group) based on the postulation of Karasek's Job Strain Model. Of them, we invited 160 male workers (40 people each subgroup) using a stratified sampling, and finally, 152 eligible participants were analyzed.

RESULTS

In multivariate analyses, we found that decision latitude was associated with cholesterol, triglyceride, and homocystein and that work demand was related to smoking and systolic blood pressure. Job strain (the combination of high work demand with low decision latitude) was significantly related to higher levels of homocystein after controlling for age, BMI, smoking, and social support at workplace.

CONCLUSIONS

These results indicate that job stress is associated with cardiovascular risk factors and might contribute to the development of cardiovascular disease. Some considerations for the future research were discussed.

Role of vitamins B6, B12 and folic acid on hyperhomocysteinemia in a Pakistani population of patients with acute myocardial infarction

BACKGROUND AND AIM

Pakistani people belong to an ethnic group which has the highest rate of coronary artery disease (CAD). We investigated the possible correlation between deficiency of vitamins B6, B12 or folic acid and hyperhomocysteinemia in Pakistani patients with acute myocardial infarction (AMI). A case-control study was carried out involving 224 AMI patients (age 30-70 years; 55 females and 169 males) and 126 normal healthy subjects (age 31-70 years; 35 females and 91 males).

METHODS AND RESULTS

Fasting venous blood was obtained from cases and controls. Serum was analyzed for folic acid and B12 using radioassays. Plasma was analyzed for pyridoxal phosphate (PLP; coenzymic form of B6) using a radioenzymatic assay and for total homocysteine using a fluorescence polarization immunoassay. Mean serum B12 concentration in AMI patients was found to be significantly lower than the mean for controls (241+/-185 pg/ml vs 608+/-341 pg/ml; p < 0.001). Mean serum folate level in patients was also found to be lower than controls (3.35+/-3.78 ng/ml vs 4.93+/-2.93 ng/ml), however, the differences were not statistically significant. Similarly, mean PLP concentration in plasma of cases (19.4+/-24.4 nmol/l) was lower than the concentration in controls (23.2+/-17.6 nmol/l), but the difference was not statistically significant. Mean plasma homocysteine level in AMI cases (18+/-8.36 micromol/l) was higher than the mean level in controls (16.4+/-4.9 micromol/l), but not to a significant extent. However, this mean homocysteine concentration in normal healthy subjects was among the highest reported in the literature and was significantly more than mean values reported in most Eastern and Western studies. Compared to controls, there was significantly greater deficiency of folate (32.5% vs 67.1%), B12 (3.2% vs 63.4%) and PLP (49.2% vs 74.1%) in AMI patients. Deficiencies of folate, B12 and PLP were defined as serum folate levels less than 3.5 ng/ml, serum levels of B12 less than 200 pg/ml and plasma PLP levels less than 20 nmol/l. Mean plasma homocysteine levels in smokers were found to be significantly higher in both cases and controls. Similarly, mean serum folate levels in smokers (compared to nonsmokers) were significantly lower in both cases and controls.

CONCLUSIONS

Substantial nutritional deficiencies of these three vitamins along with mild hyperhomocysteinemia, perhaps through an interplay with the classical cardiovascular risk factors (highly prevalent in this population), could be further aggravating the risk of CAD in the Pakistani population.

Age, sex and vitamin status affect plasma level of homocysteine, but hyperhomocysteinaemia is possibly not an important risk factor for venous thrombophilia in Taiwanese Chinese

The biological effects of age, sex and vitamin status on plasma total homocysteine (tHcy), and association of hyperhomocysteinaemia with venous thromboembolism in Taiwanese Chinese individuals, were investigated. Eighty patients (16-85 years) with venous thrombophilia and 123 healthy subjects (15-85 years) without history of vascular thrombosis were studied for plasma levels of tHcy, folate and vitamin B12. A multivariate analysis in healthy subjects revealed that plasma tHcy levels tended to increase with age (P < 0.001) and with decreasing plasma levels of folate (P=0.001) or vitamin B12 (P < 0.029); men tended to have higher plasma tHcy levels than women (P=0.006). Thrombotic risk assessment in a case-control study demonstrated that neither plasma level of tHcy [odds ratio (OR), 1.07; 95% confidence interval (CI), 0.96-1.18; P=0.210] nor hyperhomocysteinaemia (OR, 1.65; 95% CI, 0.50-5.49; P=0.415) was significantly associated with venous thrombophilia. The relationship between hyperhomocysteinaemia and recurrence of episode remained insignificant (P=0.560). We conclude that age, sex and vitamin status affect plasma tHcy but hyperhomocysteinaemia is possibly not an important risk factor for venous thrombophilia in Taiwanese Chinese.

Homocyst(e)ine and cardiovascular disease: a systematic review of the evidence with special emphasis on case-control studies and nested case-control studies

BACKGROUND

Elevated concentrations of homocyst(e)ine are thought to increase the risk of vascular diseases including coronary heart disease and cerebrovascular disease.

METHODS

We searched MEDLINE (1966-1999), EMBASE (1974-1999), SciSearch (1974- 1999), and Dissertation Abstracts (1999) for articles and theses about homocyst(e)ine concentration and coronary heart disease and cerebrovascular disease.

RESULTS

We included 57 publications (3 cohort studies, 12 nested case-control studies, 42 case-control studies) that reported results on 5518 people with coronary heart disease (11,068 control subjects) and 1817 people with cerebrovascular disease (4787 control subjects) in our analysis. For coronary heart disease, the summary odds ratios (OR) for a 5-micromol/l increase in homocyst(e)ine concentration were 1.06 (95% CI : 0.99-1.13) for 2 publications of cohort studies, 1.23 (95% CI : 1.07-1.41) for 10 publications of nested case-control studies, and 1.70 (95% CI : 1.50-1.93) for 26 publications of case-control studies. For cerebrovascular disease, the summary OR for a 5-micromol/l increase in homocyst(e)ine concentration were 1.10 (95% CI : 0.94-1.28) for 2 publications of cohort studies, 1.58 (95% CI : 1.35-1.85) for 5 publications of nested case-control studies, and 2.16 (95% CI : 1.65-2.82) for 17 publications of case-control studies.

CONCLUSIONS

Prospective studies offer weaker support than case-control studies for an association between homocyst(e)ine concentration and cardiovascular disease. Although other lines of evidence support a role for homocyst(e)ine in the pathogenesis of cardiovascular disease, more information from prospective epidemiological studies or clinical trials is needed to clarify this role.

High plasma homocyst(e)ine levels in elderly Japanese patients are associated with increased cardiovascular disease risk independently from markers of coagulation activation and endothelial cell damage

Elevated plasma homocyst(e)ine is a risk factor for cardiovascular disease (CVD) in many populations, but the relationship between homocyst(e)ine and CVD in Japanese subjects has been unclear. It has been hypothesized that the link between homocyst(e)ine and CVD may be mediated in part by activation of coagulation and endothelial cell injury in the elderly Japanese subjects. To further evaluate this hypothesis, the present cross-sectional study was designed to assess the relationships among plasma homocyst(e)ine concentrations, risk of CVD, and markers of coagulation (fibrinogen, FVII, F1+2, FVIIa and FXIIa) and endothelial cell damage (vWF and thrombomodulin) in 146 elderly Japanese subjects (79 healthy controls and 67 patients with CVD). The geometric mean (range) of plasma homocyst(e)ine concentrations was 10.2 (3.2--33) micromol/l in 79 Japanese healthy elderly subjects. As expected, healthy female and male elderly subjects had homocyst(e)ine levels that were 2.5 and 5.3 micromol/; higher, respectively, compared to healthy young control subjects (n=62). Healthy young and elderly men had homocyst(e)ine levels that were 1.7 and 4.5 micromol/l higher, respectively, compared to values in women. This higher plasma homocyst(e)ine levels in the elderly subjects were negatively correlated with levels of folic acid, albumin and total cholesterol, but were not significantly related to markers of coagulation or endothelial cell-damage. The results of multiple logistic regression analyses suggested that high homocyst(e)ine levels were independently related to CVD risk. In addition, levels of FVIIa, and F1+2 were significantly higher in elderly Japanese patients with CVD compared to elderly subjects without CVD, but were unrelated to plasma homocyst(e)ine concentrations. In summary, elevated plasma concentrations of homocyst(e)ine, FVIIa, and F1+2 were associated with increased risk of CVD in elderly male and female Japanese subjects, but the association between homocyst(e)ine and CVD was unrelated to abnormalities in markers of coagulation and endothelial cell damage in this population.

The impact of heavy passive smoking on arterial endothelial function in modernized Chinese

OBJECTIVES

The study evaluated whether heavy exposure to environmental tobacco smoke (passive smoking) might damage arterial function in modernized Chinese.

BACKGROUND

Heavy passive smoking is associated with arterial endothelial dysfunction in Caucasian, but not rural Chinese, subjects.

METHODS

We studied 20 young (mean age 36.6 +/- 7.0 years) nonsmoking asymptomatic casino workers (9 men) in Macau who were exposed to environmental tobacco smoke for over 8 h/day for at least two years and 20 normal subjects (control subjects). These two groups were carefully matched for age, gender, body mass index (BMI), blood pressure, vessel diameter, cholesterol and glucose levels. Brachial artery diameter was measured by high-resolution B-mode ultrasound at rest, after flow increase (causing flow-mediated endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator).

RESULTS

Flow-mediated dilation (mean +/- SD% of diameter changes) was significantly lower in passive smokers (6.6 +/- 3.4%) compared with the controls (10.6 +/- 2.3%) (p < 0.0001). Nitroglycerin-induced dilation of the two groups were similar. Upon multivariate analysis, passive smoking exposure was the strongest independent predictor (beta = -0.59; p = 0.0001) for impaired flow-mediated endothelium-dependent dilation (model R2 = 0.75, F value = 6.1, p = 0.0001).

CONCLUSIONS

In modernized Chinese, as in Caucasians, exposure to heavy environmental tobacco smoke causes arterial endothelial dysfunction, a key early event in atherosclerosis. This may have serious implications for cardiovascular health in China, currently in a process of rapid modernization.

Preventive health care, 2000 update: screening and management of hyperhomocysteinemia for the prevention of coronary artery disease events. The Canadian Task Force on Preventive Health Care

OBJECTIVE

To establish guidelines for the screening and treatment of hyperhomocysteinemia in the investigation and management of coronary artery disease (CAD).

OPTIONS

Measurement of plasma total homocysteine (tHcy) levels in the fasting state or 4-6 hours after oral methionine load; vitamin supplementation with folic acid and vitamins B6 and B12; adherence to the recommended daily allowance of dietary sources of folate and vitamins B6 and B12.

OUTCOMES

This article reviews the available evidence on the association between plasma tHcy levels and CAD and the effect of lowering tHcy levels through vitamin supplementation or dietary intake.

EVIDENCE

MEDLINE was searched for relevant English-language articles published from January 1966 to June 1999; also reviewed were additional articles identified from the bibliographies.

BENEFITS, HARMS AND COSTS

Cardiovascular disease is the leading cause of death in Canada. Homocysteine, generated in the metabolism of methionine, may have a role in the development of cardiovascular disease. The prevalence of hyperhomocysteinemia in the general population is between 5% and 10% and may be as high as 30%-40% in the elderly population. If population-based studies are correct, tHcy may be responsible for up to 10% of CAD events and thus may represent an important and potentially modifiable risk factor for cardiovascular disease. Laboratory testing for tHcy is currently restricted to research centres, and costs range from $30 to $50 per person. Newer, less costly techniques have been developed and should become readily available with time.

VALUES

The strength of evidence was evaluated using the methods of the Canadian Task Force on Preventive Health Care.

RECOMMENDATIONS

Although there is insufficient evidence to recommend the screening or management of hyperhomocysteinemia at present (grade C recommendation), adherence to recommended daily allowance of dietary sources of folate and vitamins B12 and B6 should be encouraged. If elevated tHcy levels are discovered, vitamin deficiency should be ruled out to allow specific treatment and prevention of complications, such as neurological sequelae due to vitamin B12 deficiency. Experts in the field advocate treatment of elevated tHcy levels in high-risk people, such as those with a personal or family history of premature atherosclerosis or a predisposition to develop hyperhomocysteinemia. Definitive guidelines for the management of hyperhomocysteinemia await the completion of randomized trials to establish the effect of vitamin supplementation on CAD events.

VALIDATION

The findings of this analysis were reviewed through an iterative process by the members of the Canadian Task Force on Preventive Health Care.

SPONSORS

The Canadian Task Force on Preventive Health Care is funded through a partnership between the Provincial and Territorial Ministries of Health and Health Canada.

Risk of pulmonary embolism and/or deep venous thrombosis in Asian-Americans

Several reports from Asian countries suggest a low prevalence of pulmonary embolism (PE) and deep venous thrombosis (DVT) in Asians, and sparse US data show that a slightly higher prevalence of PE/DVT in "nonwhites" than in whites is evident in all geographic regions except the Pacific region (California, Oregon, and Washington) where "nonwhites" include a larger proportion of Asians and Hispanics than in other US locations. We prospectively studied PE/DVT hospitalizations in 128,934 persons in relation to traits determined at health examinations in 1978 to 1985. Through 1994, 337 persons were subsequently hospitalized for PE and/or DVT (for PE first, n = 206). Cox proportional-hazards models with 9 covariates were used. In multivariate models, the following RRs (95% confidence intervals) were found for PE/DVT combined: black/white = 1.1 (0.4 to 1.4); Hispanic/white = 0.7 (0.3 to 1.5); and Asian/white = 0.2 (0.1 to 0. 5; p = 0.002). The lower risk of Asians was present in each sex and for persons first hospitalized for either PE or DVT. Covariates with significant positive relations to risk were age, male sex, body mass index, and a composite coronary disease risk/symptom variable; covariates not significantly related were education, marital status, smoking, and alcohol. These data suggest that Asians have very low risk of PE/DVT, which may account for US geographic variations in white/non-white risk differences. Possible explanations include the absence of hazardous mutations or unspecified PE/DVT protective traits in Asians.

Moderate hyperhomocyst(e)inemia is associated with the presence of coronary artery disease and the severity of coronary atherosclerosis in Koreans

To examine whether moderate hyperhomocyst(e)inemia is associated with coronary artery disease and the number of diseased coronary vessels in Koreans, we investigated 201 patients with angiographically documented coronary artery disease and 187 healthy subjects without evidence of stroke and coronary artery disease. The mean plasma total homocysteine in patients was higher than in controls (10.3 micromol/L; 95% confidence interval, 7.0-13.6 vs. 8.9 micromol/L; 6.0-11.8) (p=0.005). The prevalence of moderate hyperhomocyst(e)inemia, defined as the top 90th percentile in controls (13.2 micromol/L), was higher in patients than in controls (23.9% vs. 10.2%, p=0.001). Plasma homocyst(e)ine levels were not correlated to age, body mass index, levels of serum cholesterol, creatinine, and uric acid. Based on multiple logistic regression analyses with adjustment for total cholesterol, hypertension, smoking status, diabetes, age, and body mass index, the adjusted odds ratio of moderate hyperhomocyst(e)inemia for coronary artery disease was 1.53 (95% confidence interval: 1.39-1.65, p=0.0001). Moderate hyperhomocyst(e)inemia, diabetes mellitus, and old age were more prevalent in patients with triple-vessel disease than in single- or double-vessel disease (p=0.02). Multiple logistic regression analysis revealed that moderate hyperhomocyst(e)inemia was a significant predictor of triple-vessel disease with odds ratio of 2.78 (95% confidence interval: 1.08-7.10, p=0.02). We conclude that moderate hyperhomocyst(e)inemia is an independent risk factor for coronary artery disease, and also related significantly to the presence of triple-vessel disease.

[Laboratory diagnosis in preventive cardiology]

In recent years a large number of coronary artery disease risk factors were discovered. The knowledge of these factors improves the estimate of the coronary artery disease (CAD) risk--however it still remains to be only an "estimate". A perfect prediction of an upcoming CAD event is not possible, despite all high score laboratory technology. Therefore the use of specialized laboratory procedures should be applied carefully. Knowing the blood levels of cholesterol, triglycerides, HDL- and LDL-cholesterol and Lp(a) can be sufficient for many therapeutical decisions. Severe dyslipidemia, familial CAD and CAD without any obvious reasons demand a more specialized work-up, however, risk stratification factors such as family history, clinical history (CAD, hypertension, diabetes mellitus, smoker) and genetics are crucial, apart from the above mentioned laboratory values. Purely on the basis of the lipidologic baseline concentrations we can't give well based recommendations for the treatment of individual patients. Currently there are expert systems available which allow a risk estimate once important laboratory values (LDL cholesterol, HDL cholesterol, Triglycerides) as well as clinical data (blood pressure, family history, clinical history) are available. This system can be accessed by internet under "http:/(/)www.chd-taskforce.com".

Homocysteine, a Risk Factor for Cardiovascular Disease

Fasting hyperhomocysteinemia is an independent risk factor for coronary artery disease, stroke, peripheral vascular atherosclerosis, and for arterial and venous thromboembolism. The risk for cardiovascular disease with homocysteine is similar to conventional risk factors. The interaction of hyperhomocysteinemia with hypertension and smoking is strong and the combined effect is more than multiplicative. The combined effect of homocysteine and cholesterol is additive. Homocysteine produces atherosclerosis, thromboembolism, and vascular endothelial cell injury. Vascular dysfunction produced by homocysteine may be due to endothelial cell damage. Homocysteinemia-induced atherosclerosis is probably due to various factors including endothelial cell injury, inability to sustain S-nitroso-homocysteine formation because of imbalance between production of nitric oxide by dysfunctional endothelium and homocysteine, smooth muscle cell proliferation, and thromboembolism. There is strong evidence that endothelial cell injury is associated with oxidative stress produced by homocysteine. Hyperhomocysteinemia is associated with numerous conditions, including coronary disease, stroke, peripheral vascular disease (carotid artery and cerebrovascular atherosclerosis), venous thrombosis, renal disease, diabetes mellitus, and organ transplant. Folic acid, vitamin B12 and B6 have been shown to be beneficial in reducing plasma homocysteine levels. Folic acid is specifically very effective, safe and inexpensive.

Homocysteine and cardiovascular disease

An elevated level of total homocysteine (tHcy) in blood, denoted hyperhomocysteinemia, is emerging as a prevalent and strong risk factor for atherosclerotic vascular disease in the coronary, cerebral, and peripheral vessels, and for arterial and venous thromboembolism. The basis for these conclusions is data from about 80 clinical and epidemiological studies including more than 10,000 patients. Elevated tHcy confers a graded risk with no threshold, is independent of but may enhance the effect of the conventional risk factors, and seems to be a particularly strong predictor of cardiovascular mortality. Hyperhomocysteinemia is attributed to commonly occurring genetic and acquired factors including deficiencies of folate and vitamin B12. Supplementation with B-vitamins, in particular with folic acid, is an efficient, safe, and inexpensive means to reduce an elevated tHcy level. Studies are now in progress to establish whether such therapy will reduce cardiovascular risk.

New risk factors for coronary heart disease in Asia

The increasing prevalence of traditional atherosclerotic risk factors have been documented in Asia but the real impact on prevalence of coronary heart disease (CHD) remains unclear. Smoking, hypertension, hypercholesterolaemia, diabetes mellitus and obesity are present in only 50% of CHD. In community studies of Chinese in Hong Kong and southern mainland-China, aging, smoking and hypercholesterolaemia were found to have a less impact on endothelial function in the Chinese compared with Caucasians in London and Sydney. As endothelial dysfunction is an early event in atherogenesis, there will be a strong need to search for newer risk factors for CHD in Asia, which may become more important in many Asian countries now in the process of modernization. Recently, heterozygous hyperhomocysteinaemia (with or without folate deficiency) was found to be an independent risk factor for arterial endothelial dysfunction, and hyperhomocysteinaemia in association with smoking was a significant risk factor for premature coronary heart disease in Hong Kong Chinese. Other newer factors which have emerged include folate deficiency, low HDL-cholesterol, insulin resistance, abdominal obesity, Methylene-tetrahydrofolate Reductase and Angiotensin Converting Enzyme gene polymorphism.

Hyperhomocyst(e)inemia is a risk factor for arterial endothelial dysfunction in humans

BACKGROUND

Hyperhomocyst(e)inemia is associated with premature peripheral vascular, cerebrovascular, and coronary artery disease. Because homocysteine has been found to be damaging to endothelial cells in animal and cell culture studies, we evaluated the association between hyperhomocysteinemia and arterial endothelial dysfunction (a marker of early atherosclerosis) in asymptomatic adult subjects.

METHODS AND RESULTS

Using high-resolution ultrasound, we measured endothelium-dependent flow-mediated dilation (EDD) and endothelium-independent nitroglycerin-induced dilation (GTN) of the brachial artery in 14 prospectively defined hyperhomocysteinemic (mean plasma homocysteine, 34.8+/-8.5 micromol/L), nonsmoking, healthy subjects aged 53+/-9 years and 14 control subjects with low plasma homocysteine levels (9.9+/-3.2 micromol/L). The two groups were well matched for age; sex; body mass index; blood pressure, blood cholesterol, folate, and vitamin B12 levels; and vessel diameter. EDD was significantly lower in hyperhomocysteinemic subjects (6.5+/-1.7%) than in subjects with low homocysteine levels (10.8+/-1.7%) (P<.001). GTN responses were similar in the two subject groups (P=.90). Multivariate analysis confirmed homocysteine level as the strongest predictor for impaired EDD, independent of age, sex, body mass index, or blood pressure, folate, vitamin B12, and cholesterol levels.

CONCLUSIONS

Hyperhomocysteinemia is an independent risk factor for arterial endothelial dysfunction in healthy middle-aged adults.

Hyperhomocysteinaemia, Helicobacter pylori, and coronary heart disease

Hyperhomocysteinaemia and Helicobacter pylori infection have recently been implicated in the pathogenesis of coronary artery disease. These two risk factors, though they seem unrelated, could be linked by a deficiency of vitamins and folate caused by chronic gastritis in H pylori infection. This nutritional defect could lead to failure of methylation by 5-methyl-tetrahydrofolic acid and thus exacerbate the accumulation of homocysteine in susceptible patients. Homocysteine is toxic to endothelial cells and results in coronary artery disease.