Homocyst(e)ine and coronary heart disease: pharmacoeconomic support for interventions to lower hyperhomocyst(e)inaemia

Rationale and design for the CARDIOVIT Study (Cardiovit, Atherosclerotic vascular disease and hypeRhomocysteinemia: an epiDemiological study in Indians, additionally evaluating the effect of Oral VITamin supplementation)

BACKGROUND AND RATIONALE

Atherosclerotic vascular disease (AVD), including coronary heart disease (CHD), is on the rise in India. Mortality due to CHD is estimated to be 40% higher in Indian Asians compared with Europeans. Hyperhomocyst(e)inaemia (hypertHcy) is emerging as a novel independent risk factor for AVD. Moreover, there is increasing evidence of its association with CHD in subjects of Indian origin possibly because of inadequate folic acid and B(12) status. However, there is a lack of epidemiological data on its prevalence in Indians. A need to evaluate the optimum dose of folic acid required to reduce plasma homocyst(e)ine (tHcy) also exists.

OBJECTIVES AND METHODS

The CARDIOVIT study, divided into two stages, is designed to determine the prevalence and relevance of hypertHcy in Indian subjects and also evaluate the tHcy-lowering effect of a marketed multivitamin formulation (Cardiovit). Stage I is a cross-sectional epidemiological study to estimate the prevalence of hypertHcy in a randomly selected population in South India. We planned to screen 2000 subjects between 25 and 64 years of age for established risk factors; plasma tHcy levels will be estimated and the correlation of AVD with established risk factors, plasma tHcy and nutritional factors was evaluated. Subjects having tHcy levels > 12 micromol/L are recruited in Stage II; a randomized, three-arm, double-blind, double-dummy, placebo-controlled, parallel-group, comparative study designed to evaluate the tHcy-lowering effect of a multivitamin formulation containing 300 microg folic acid, 1 microg vitamin B(12) and 1.5 mg vitamin B(6), along with Vitamins A, C, E and selenium. Subjects will be randomized into three groups (n = 64 completed subjects each) and receive either two placebos, or one placebo and multivitamin, or two multivitamin tablets for 6 weeks. Serum vitamin B(12), serum and red cell folate are estimated at baseline and at 6 weeks. Descriptive, univariate analysis, multiple logistic regression model and appropriate statistical tests will be used to analyse the prevalence of hypertHcy, association with risk factors of AVD, efficacy and safety of the multivitamin formulation and other data per protocol.

CONCLUSIONS

CARDIOVIT is one of the first and largest studies in India to provide insight into the prevalence of hypertHcy, its association with AVD and conventional risk factors and the role of multivitamins in reducing it.

Impact of Elevated Plasma Total Homocysteine Concentration on Coronary Atherosclerosis in Chinese Patients With Acute Myocardial Infarction Undergoing Primary Coronary Intervention

Elevated plasma total homocysteine (tHcy) has been considered to be a new risk factor for coronary atherosclerotic disease. However, the association has not been proven indisputably, and the strength of the relationship and the interaction of plasma tHcy with other conventional risk factors remain uncertain in the clinical setting of acute myocardial infarction (AMI). The aim of this study was to investigate whether an elevated plasma level of tHcy is an independent predictor of the late stage of coronary atherosclerotic lesions in Chinese patients with AMI, who are undergoing primary percutaneous coronary intervention (PCI). Plasma levels of tHcy were prospectively measured in 178 consecutive patients with ST-segment elevated AMI undergoing primary PCI. The plasma level of tHcy was also measured in 30 control subjects with normal coronary angiographic findings. The plasma level of tHcy was significantly higher in the patients with AMI than in control subjects (10.5 +/- 3.3 micromol/L versus 8.3 +/- 2.4 micromol/L, P = 0.0004). Multiple stepwise logistic regression analysis of the baseline characteristics demonstrated that smoking (P = 0.004) and creatinine level (P < 0.0001) were independent predictors of an elevated plasma level of tHcy. Moreover, an increased plasma level of tHcy (P = 0.003), female gender (P = 0.008), diabetes mellitus (P = 0.020), and the presence of previous myocardial infarction (P = 0.003) were independent predictors of the late stage of multivessel diffuse atherosclerosis (defined by > or = 2 epicardial vessels with moderate or severe diffuse atherosclerosis). In conclusion, this investigation supports the hypothesis that a raised homocysteine concentration is a strong risk factor for the late stage of diffuse coronary atherosclerosis in Chinese patients with AMI undergoing primary PCI. This result therefore raises the prospect of the need for major therapeutic research in Chinese patients.

Describing a folic acid intervention for health care providers: implications for professional practice and continuing education

The purpose of this article is to, first, describe the content of a folic acid professional education intervention that was developed and implemented as a result of a collaborative effort between an academic institution and a nonprofit organization-the Pittsburgh, Pennsylvania, chapter of the March of Dimes-and the process by which it was developed; second, report the results of an evaluation of the impact of this intervention on knowledge and recommendation behaviors of health care providers; and third, discuss the implications for professional practice and continuing education. We developed a novel presentation that had practical utility for practitioners that could be implemented in either a classroom or continuing education setting.

Homocysteine and folic acid are inversely related in black women with preeclampsia

Black women have an increased risk of preeclampsia compared with white women. Plasma homocysteine is increased in preeclampsia. Homocysteine concentrations are affected by nutritional deficiencies, particularly decreased folic acid and B12, leading to increased homocysteine. Previous studies have reported racial differences in nutritional intake including folic acid. Therefore, we investigated whether there were racial differences in plasma homocysteine, folic acid, and vitamin B12 among women with preeclampsia. We tested for an association between homocysteine and folic acid and B12, and we hypothesized an inverse relationship of homocysteine and folic acid in preeclampsia, more so in black women in whom preeclampsia developed. Black women with preeclampsia (n=26) had elevated homocysteine concentrations (8.7+/-1.4 micromol/L) compared with black women with normal pregnancy (n=52, 7.6+/-0.5 micromol/L), white women with preeclampsia (n=34, 7.5+/-0.6 micromol/L), and white women with normal pregnancy (n=48, 5.5+/-0.3 micromol/L). Folic acid concentrations were lower in black women (14.1+/-0.8 ng/mL) compared with white women (18.5+/-0.9 ng/mL, P<0.01). However, plasma homocysteine was inversely related to folic acid only among black women with preeclampsia (r=-0.23, P=0.01). These racial differences may have implications for the higher rates of preeclampsia in this group and may have long-term implications for future cardiovascular risk. Racial differences in diet, adherence to folic acid supplementation, or interactions of nutritional and maternal factors warrant further study by race and pregnancy status.

DACH-LIGA homocystein (german, austrian and swiss homocysteine society): consensus paper on the rational clinical use of homocysteine, folic acid and B-vitamins in cardiovascular and thrombotic diseases: guidelines and recommendations

About half of all deaths are due to cardiovascular disease and its complications. The economic burden on society and the healthcare system from cardiovascular disability, complications, and treatments is huge and getting larger in the rapidly aging populations of developed countries. As conventional risk factors fail to account for part of the cases, homocysteine, a "new" risk factor, is being viewed with mounting interest. Homocysteine is a sulfur-containing intermediate product in the normal metabolism of methionine, an essential amino acid. Folic acid, vitamin B12, and vitamin B6 deficiencies and reduced enzyme activities inhibit the breakdown of homocysteine, thus increasing the intracellular homocysteine concentration. Numerous retrospective and prospective studies have consistently found an independent relationship between mild hyperhomocysteinemia and cardiovascular disease or all-cause mortality. Starting at a plasma homocysteine concentration of approximately 10 micromol/l, the risk increase follows a linear dose-response relationship with no specific threshold level. Hyperhomocysteinemia as an independent risk factor for cardiovascular disease is thought to be responsible for about 10% of total risk. Elevated plasma homocysteine levels (>12 micromol/l; moderate hyperhomocysteinemia) are considered cytotoxic and are found in 5 to 10% of the general population and in up to 40% of patients with vascular disease. Additional risk factors (smoking, arterial hypertension, diabetes, and hyperlipidemia) may additively or, by interacting with homocysteine, synergistically (and hence over-proportionally) increase overall risk. Hyperhomocysteinemia is associated with alterations in vascular morphology, loss of endothelial anti-thrombotic function, and induction of a procoagulant environment. Most known forms of damage or injury are due to homocysteine-mediated oxidative stress. Especially when acting as direct or indirect antagonists of cofactors and enzyme activities, numerous agents, drugs, diseases, and lifestyle factors have an impact on homocysteine metabolism. Folic acid deficiency is considered the most common cause of hyperhomocysteinemia. An adequate intake of at least 400 microg of folate per day is difficult to maintain even with a balanced diet, and high-risk groups often find it impossible to meet these folate requirements. Based on the available evidence, there is an increasing call for the diagnosis and treatment of elevated homocysteine levels in high-risk individuals in general and patients with manifest vascular disease in particular. Subjects of both populations should first have a baseline homocysteine assay. Except where manifestations are already present, intervention, if any, should be guided by the severity of hyperhomocysteinemia. Consistent with other working parties and consensus groups, we recommend a target plasma homocysteine level of <10 micromol/l. Based on various calculation models, reduction of elevated plasma homocysteine concentrations may theoretically prevent up to 25% of cardiovascular events. Supplementation is inexpensive, potentially effective, and devoid of adverse effects and, therefore, has an exceptionally favorable benefit/risk ratio. The results of ongoing randomized controlled intervention trials must be available before screening for, and treatment of, hyperhomocysteinemia can be recommended for the apparently healthy general population.

Comparative effects of atorvastatin, simvastatin, and fenofibrate on serum homocysteine levels in patients with primary hyperlipidemia

Hyperhomocysteinemia is regarded as an independent risk factor for cardiovascular disease. Lipid-lowering agents, such as fibrates, can modify homocysteine levels. However, less is known about the effect of statin therapy on homocysteine. The authors compared the effects of atorvastatin (40 mg/day), simvastatin (40 mg/day), and micronized fenofibrate (200 mg/day) on the serum concentrations of total homocysteine, vitamin B12, and folic acid in patients with primary hyperlipidemia. A total of 128 patients with primary hyperlipidemia (total cholesterol > 240 mg/dL and triglycerides < 350 mg/dL) were assigned to atorvastatin, simvastatin, or fenofibrate. Serum lipid and metabolic parameters were measured at baseline and at 6 and 12 weeks of treatment. Homocysteine correlated positively with serum creatinine and uric acid levels and inversely with serum folic acid levels. All treatment modalities reduced total, low-density lipoprotein (LDL) cholesterol, and triglyceride concentrations. High-density lipoprotein (HDL) cholesterol levels significantly increased only in the fenofibrate-treated patients (47.9 +/- 12.5 vs. 50.7 +/- 12.6 vs. 51.2 +/- 12.8 mg/dL, p < 0.01). Atorvastatin and fenofibrate treatment resulted in a significant reduction of serum uric acid levels (5.3 +/- 1.6 vs. 4.9 +/- 1.4 vs. 4.8 +/- 1.4 mg/dL, p < 0.0001 for atorvastatin; 5.6 +/- 1.6 vs. 4.3 +/- 1.4 vs. 4.4 +/- 1.4 mg/dL, p < 0.0001 for fenofibrate). Homocysteine levels were significantly increased only by fenofibrate (10.3 +/- 3.3 vs. 14.1 +/- 3.8 vs. 14.2 +/- 3.6 microU/L, p < 0.001) but did not change from baseline following statin treatment. Neither statins nor fenofibrate had any effect on serum vitamin B12 and folic acid levels. In contrast to fenofibrate, therapeutic dosages of atorvastatin and simvastatin have a neutral effect on serum homocysteine levels, which is in favor of their "cardioprotective" properties.