Association between plasma homocysteine concentration and carotid atherosclerosis in hemodialysis patients

Circulating plasma antioxidants, inflammatory markers and asymptomatic carotid atherosclerosis in end-stage renal disease patients: a case control study

Few studies have been conducted on the relationship between antioxidant plasma vitamin concentrations, inflammatory markers and carotid atherosclerosis with inconclusive results in endstage renal disease (ESRD) patients. A case-control study was performed to investigate the relationship between plasma antioxidant concentrations, inflammatory markers, and carotid intima-media thickness (CIMT) in healthy subjects and in patients undergoing hemodialysis (HD). We enrolled 40 subjects (20 healthy, 20 with ESRD) asymptomatic for carotid atherosclerosis. After carotid ultrasound investigation (CUI), medical history data, physical examination, venous blood samples were collected. These were analyzed for concentrations of antioxidant vitamins (A, E), carotenoids (lycopene, beta-carotene), inflammatory markers (C-reactive protein, fibrinogen), and lipid profile. Low concentrations of vitamin A, vitamin E, lycopene, and beta-carotene were significantly associated with carotid atherosclerosis in patients with ESRD (p less than 0.001). In addition, high concentration of low density lipoprotein cholesterol and total cholesterol (p less than 0.01), C-reactive protein and fibrinogen (p less than 0.001) were also associated with carotid atherosclerosis, while other laboratory parameters considered (high density lipoprotein cholesterol and triglycerides) were not significantly associated with carotid atherosclerosis. A regular intake of foods rich in antioxidant vitamins with low fat concentrations may slow the progression of atherosclerotic process in this group of patients.

Differential associations of traditional and non-traditional risk factors with carotid intima-media thickening and plaque in peritoneal dialysis patients

BACKGROUND

This study sought to examine the associations of traditional and non-traditional cardiovascular risk factors with carotid intima-media thickening and plaque in peritoneal dialysis (PD) patients.

METHODS

A cross-sectional study was performed in 147 PD patients with carotid intima-media thickness (IMT) and plaque assessed by B-mode ultrasonography and fasting blood collected for biochemical measurements.

RESULTS

On univariate analysis, age, smoking history, fibrinogen, C-reactive protein (CRP), adiponectin, fetuin-A, lipoprotein(a) and diastolic blood pressure were associated with carotid IMT while age, smoking history, diabetes, CRP and diastolic blood pressure were associated with carotid plaque. Using multivariate analysis, elevated CRP (p = 0.015) and serum calcium (p = 0.022) were associated with carotid plaque but not with IMT. CRP and serum calcium were synergistically associated with carotid plaque in that those with CRP > median and serum calcium > median showed the highest prevalence of carotid plaque than either factor alone (p = 0.003).

CONCLUSIONS

An elevated CRP appeared to be a better biomarker of presence of carotid plaque than intima-media thickening. Furthermore, CRP and serum calcium showed synergistic association with presence of carotid plaque. However, our study was limited by the cross-sectional design and baseline laboratory abnormalities were inevitably confounded by the treatment already given, resulting in difficulty to distinguish cause and effect relationship. Nevertheless, these observations warrant further investigation as it may potentially have important implications on differentiating therapeutic strategies for reducing carotid IMT and plaque progression in PD patients.

Atherosclerosis in haemodialysis patients without significant comorbidities: determinants of progression

AIM

The aim of this prospective study was to assess the determinants of the progression of carotid artery intima-media thickness (CA-IMT) for 1 year in haemodialysis (HD) patients without significant comorbidities.

METHODS

Fifty-four HD patients younger than 55 years, without diabetes, obesity and any clinical evidence of cardiovascular disease (29 men, 25 women; mean age 33.3 +/- 10 years; mean time on HD 49.4 +/- 43 months) were included in the 1-year study. CA-IMT was assessed at baseline and after 12 months. The difference in IMT between these two points of time was calculated (DeltaCA-IMT). C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), haematocrit-corrected ESR, beta-2 microglobulin, cardiac troponin I, lipid profile, fibrinogen, homocysteine, CaXP product, intact parathyroid hormone, haematocrit, albumin, uric acid levels, anthropometric parameters (age, body mass index), smoking, hypertension and left ventricular hypertrophy were recorded at baseline.

RESULTS

The mean value for CA-IMT at baseline (0.59 +/- 0.05 mm) was significantly lower than that at 12 months (0.64 +/- 0.07 mm) (P < 0.001). CA-IMT had increased in 41 patients (75.9%). Age (P = 0.02), CRP (P = 0.03), beta-2 microglobulin (P = 0.001) and left ventricular hypertrophy (P = 0.01) were independently related with CA-IMT at baseline. Age (P = 0.003) and CRP (P = 0.04) were the independent variables related with CA-IMT, measured at 12 months. DeltaCA-IMT correlated positively with age (r = 0.31, P < 0.05). Age and sex were independent predictors of DeltaCA-IMT (R(2) for the model 0.56).

CONCLUSION

In addition to age and male sex, non-specific inflammation may have a possible role in the progression of atherosclerosis in HD patients without significant comorbidities.

Cardiac troponin I and beta 2 microglobulin as risk factors for early-onset atherosclerosis in patients on haemodialysis

AIM

To investigate the associations of different risk factors with carotid artery intima-media thickness (C-IMT) in non-diabetic haemodialysis (HD) patients who had no clinical evidence of atherosclerosis.

METHODS

Seventy-two HD patients (43 men, 29 women; mean age: 34.5 +/- 10.6 years; mean time on HD: 47.9 +/- 40.0 months) and 40 age- and sex-matched healthy controls (26 men, 14 women; mean age: 35.5 +/- 7.1 years) participated in the study. The relationship between C-IMT and haematocrit-corrected erythrocyte sedimentation rate (Hct-corrected ESR), beta 2 microglobulin (beta2M) and serum cardiac troponin I (cTnI) levels beyond C-reactive protein (CRP), lipid profile and lipoprotein(a), fibrinogen, homocysteine and left ventricular hypertrophy (LVH) were examined.

RESULTS

Mean C-IMT of the HD patients was significantly greater than that of the control subjects (0.59 +/- 0.06 vs 0.53 +/- 0.07 mm, P = 0.002). C-IMT of patients was positively correlated with age (r = 0.33), body mass index (r = 0.40), Hct-corrected ESR (r = 0.37), CRP (r = 0.34), beta2M (r = 0.34), cTnI (r = 0.26), triglyceride (r = 0.26) and fibrinogen (r = 0.28) levels (P < 0.05 for all). The mean C-IMT was significantly greater in patients with LVH than it was in those without LVH (P = 0.004). In multivariate regression analysis, age (P = 0.02), beta2M (P = 0.001), log-transformed CRP (P = 0.03) and LVH (P = 0.01) were independently related with C-IMT.

CONCLUSION

Besides well-known cardiovascular (CV) risk factors, cTnI and beta2M were related with C-IMT in that they may have important roles in early-onset atherosclerosis in this high-risk population.

Homocysteine and carotid intima-media thickness: a critical appraisal of the evidence

This review examines the relationship between hyperhomocysteinemia, a risk factor for vascular disease, and carotid intima-media thickness (CIMT), a valid marker of generalized atherosclerosis and future vascular disease risk. The relationship between two important determinants of hyperhomocysteinemia in the general population-folate status and the 677C --> T methylenetetrahydrofolate reductase (MTHFR) polymorphism-and CIMT is also covered.

METHODS

We searched literature databases for articles examining homocysteine and CIMT published before September 2003.

RESULTS

We identified 54 studies. Observational studies generally failed to demonstrate a relationship between homocysteine and CIMT in homocystinuric, uremic, hypercholesterolemic or non-insulin-dependent diabetes mellitus patients or in subjects with insulin insensitivity. Weak associations, but usually only in certain sub-populations were found in vascular disease patients and in population-based studies. B vitamins reduce the progression of CIMT in renal transplant recipients and vascular disease patients as demonstrated by two trials. The majority of studies demonstrated increased CIMT in individuals with the MTHFR 677TT genotype. Folate status showed no relation to CIMT.

DISCUSSION

In non-patient populations, hyperhomocysteinemia is weakly associated with CIMT. The association of the 677 C--> T MTHFR polymorphism with CIMT further supports this finding. Lastly, folate levels may need to reach a critically low status before an association can be found between folate and CIMT. Larger trials in various population types are needed to determine whether folate alone or in combination with Vitamins B6 and B12 will slow down or even reverse atherosclerotic progression.

Impact of carotid atherosclerosis on long-term mortality in chronic hemodialysis patients

BACKGROUND

Cardiovascular event is the major cause of mortality in patients on maintenance hemodialysis. We prospectively tested the predictive values of atherosclerotic parameters for all-cause and cardiovascular outcomes in 219 hemodialysis patients (age, 58 +/- 13 years; time on hemodialysis, 13 +/- 7 years; male/female, 144/75).

METHODS

We measured blood homocysteine (Hcy), ultrasound carotid artery intima media thickness (IMT) and % aortic wall calcification at L2/3 region [% of calcification index in the abdominal aortic wall (%ACI)] by computed tomography (CT) scan, and followed all patients for 5 years.

RESULTS

During the follow-up periods, 54 patients (25%) died, 40 (74%) of them of cardiovascular causes. IMT was significantly higher in patients who expired (0.75 +/- 0.02 mm) than in those who survived (0.62 +/- 0.01 mm). IMT was significantly correlated with age (r = 0.47, P < 0.01) and %ACI (r = 0.27, P < 0.01). The survival rate during the observation was significantly lower in the final IMT third (58%) than in the first (90%) and the middle IMT third (80%) (P < 0.01). Multivariate Cox proportional hazards analysis revealed that diabetes and IMT became independent determinants of all-cause and cardiovascular death. Adjusted hazards ratios of all-cause and cardiovascular mortality for an increase of 0.1 mm in IMT were 1.31 (95% CI, 1.07 to 1.59) and 1.41 (95% CI, 1.12 to 1.76). In contrast, %ACI at abdominal aorta and blood Hcy did not affect their 5-year mortality.

CONCLUSION

These findings suggested that measurement of carotid artery IMT is useful for predicting long-term mortality in patients receiving maintenance hemodialysis.

Advanced atherosclerosis in predialysis patients with chronic renal failure

BACKGROUND

Atherosclerosis is advanced in hemodialysis patients as shown by increased intima-media thickness of carotid arteries (CA-IMT), although it is not established whether the advanced atherosclerosis results from hemodialysis treatment or from chronic renal failure. The purpose of this study was to evaluate the effects of hemodialysis and renal failure on CA-IMT in patients with chronic renal failure.

METHODS

CA-IMT was measured by high-resolution B-mode ultrasonography in 110 patients with chronic renal failure before starting dialysis (CRF group), and compared with CA-IMT of 345 hemodialysis patients (HD group) and 302 healthy control subjects. They were all nondiabetic and the three groups were comparable in age and gender.

RESULTS

As compared with the healthy control subjects, the CRF and HD groups had greater CA-IMTs, whereas CA-IMTs of the CRF and HD groups were not statistically different. There was no significant correlation between duration of hemodialysis and CA-IMT in the HD group. Multiple regression analysis in the total subjects indicated that presence of renal failure, but not being treated with hemodialysis, was a significant factor associated with increased CA-IMT independent of age, gender, blood pressure, smoking, high-density lipoprotein (HDL) and non-HDL cholesterol levels.

CONCLUSIONS

These results demonstrate that thickening of arterial wall is present in patients with chronic renal failure before starting hemodialysis treatment, and support the concept that advanced atherosclerosis in hemodialysis patients is due not to hemodialysis treatment, but to renal failure and/or metabolic abnormalities secondary to renal failure.

Plasma level of homocysteine is inversely-associated with the development of collateral circulation in patients with single-vessel coronary artery disease

Homocysteine induces endothelial injury and inhibits endothelial cell proliferation, which is a key role in angiogenesis. The purpose of this study was to investigate whether the plasma level of homocysteine is associated with the development of collaterals in patients with single-vessel coronary artery disease (CAD). Among a series of 105 male patients with angiographic estimation, 49 with single-vessel CAD were intensively investigated. Development of collaterals was classified by Rentrop's method. Univariate and multivariate analyses revealed that hyperhomocysteinemia negatively affected the development of collaterals (p=0.0015 and 0.0011, odds ratio 0.69, 95% confidence interval 0.52-0.90), whereas the duration of angina and percent stenosis evaluated by quantitative coronary angiography had a positive affect. Moreover, the level of homocysteine in the group with poorly developed collaterals (n=7, Rentrop class 0 and 1) was significantly higher than that in the group with well-developed collaterals (n=12, Rentrop class 2 and 3) of the patients with single-vessel disease showing total occlusion (p=0.034). This study clearly demonstrates that the plasma level of homocysteine is independently and inversely associated with the development of collateral circulation in CAD patients. Homocysteine might be a new undesirable aspect of ischemic heart disease through its inhibition of collateral development.

Management of nutritional problems in subacute care

Poor nutritional status is one of the major factors associated with functional decline and mortality in older persons. Older persons are at increased risk for malnutrition because of the physiologic anorexia of aging. During a stay in a subacute care facility, attention to nutrition is a major component of the rehabilitative process. The pathophysiology of malnutrition, diagnostic techniques available to diagnose malnutrition, causes and management of protein energy malnutrition, specific nutritional problems caused by vitamin and trace element deficiency, and nutritional management of specific diseases (e.g., hip fracture and diabetes mellitus) are reviewed.

The controversy over homocysteine and cardiovascular risk

Elevated plasma total homocysteine (tHcy) is a risk factor for occlusive cardiovascular disease (CVD). This concept is based on the observations of premature vascular disease in patients with homocystinuria, the relation between tHcy and both clinical CVD as well as preclinical atherosclerotic disease, the relation between tHcy in children and CVD in their parents or relatives, and reduction in CVD or surrogate endpoints after tHcy-lowering intervention with B vitamins. Plausible mechanisms include the in vivo interference with nitric oxide-dependent reactive vasodilatation. Some observations have raised questions about tHcy as a risk factor. 1) Some prospective studies showed a weak relation or no relation between tHcy and CVD. 2) Several traditional risk factors are associated with tHcy and may confound the relation between tHcy and CVD. 3) tHcy is related to renal function, and hyperhomocysteinemia may reflect early nephrosclerosis. 4) The C677T transition of the methylenetetrahydrofolate reductase gene causes a moderate increase in tHcy but no or only minor increased CVD risk. However, the strength of some of these arguments can be questioned because there is increasing evidence that tHcy is a proximate risk factor provoking the acute event, it strongly interacts with traditional risk factors, and it may predict CVD or death in patients with chronic renal failure. Furthermore, the studies of the C677T polymorphism lack statistical power, and the TT genotype may even modulate CVD risk independently of homocysteine. Thus, only placebo-controlled intervention studies with tHcy-lowering B vitamins and clinical endpoints can provide additional valid arguments for the debate over whether tHcy is a causal CVD risk factor.