Coronary artery calcification and coronary flow velocity in haemodialysis patients

Chronic Kidney Disease Associated with Ischemic Heart Disease: To What Extent Do Biomarkers Help?

Chronic kidney disease represents a complex and multifaceted pathology characterized by the presence of structural or functional renal anomalies associated with a persistent reduction in renal function. As the disease progresses, complications arise due to the chronic inflammatory syndrome, hydro-electrolytic disorders, and toxicity secondary to the uremic environment. Cardiovascular complications are the leading cause of death for these patients. Ischemic cardiac pathology can be both a consequence and complication of chronic kidney disease, highlighting the need to identify specific cardiorenal dysfunction biomarkers targeting pathophysiological mechanisms common to both conditions. This identification is crucial for establishing accurate diagnoses, prognoses, and risk stratifications for patients. This work is intended to elucidate the intricate relationship between chronic kidney disease and ischemic heart disease and to investigate the roles of cardiorenal biomarkers, including cardiac troponin, natriuretic peptides, galectin-3, copeptin, fibroblast growth factor 23 and its co-receptor Klotho, soluble suppression of tumorigenicity 2, and plasma growth differentiation factor 15.

Cardiovascular Calcifications Are Correlated with Inflammation in Hemodialysis Patients

Background and Objectives: The main cause of morbidity and mortality in hemodialysis patients is cardiovascular disease, which is quite common. The main objective of our study was to investigate the relationship between oxidative stress, inflammation, and vascular and valvular calcifications in hemodialysis patients. Materials and Methods: This observational study had 54 hemodialysis patients, with an average age of 60.46 ± 13.18 years. Cardiovascular ultrasound was used to detect and/or measure aortic and mitral valve calcifications, carotid and femoral atheroma plaques, and common carotid intima-media thickness. The aortic calcification score was determined using a lateral abdomen plain radiograph. The inflammatory, oxidative, metabolic, and dietary statuses, as well as demographic characteristics, were identified. Results: There were significant correlations between the levels of IL-6 and carotid plaque number (p = 0.003), fibrinogen level and aortic valve calcifications (p = 0.05), intima-media thickness (p = 0.0007), carotid plaque number (p = 0.035), femoral plaque number (p = 0.00014), and aortic calcifications score (p = 0.0079). Aortic annulus calcifications (p = 0.03) and intima-media thickness (p = 0.038) were adversely linked with TNF-α. Nutrition parameters were negatively correlated with atherosclerosis markers: number of carotid plaques with albumin (p = 0.013), body mass index (p = 0.039), and triglycerides (p = 0.021); number of femoral plaques with phosphorus (0.013), aortic calcifications score with albumin (p = 0.051), intima-media thickness with LDL-cholesterol (p = 0.042). Age and the quantity of carotid plaques, femoral plaques, and aortic calcifications were linked with each other (p = 0.0022, 0.00011, and 0.036, respectively). Aortic annulus calcifications (p = 0.011), aortic valve calcifications (p = 0.023), and mitral valve calcifications (p = 0.018) were all associated with an increased risk of death. Conclusions: Imaging measures of atherosclerosis are adversely connected with dietary status and positively correlated with markers of inflammation and risk of mortality.

Association of Serum Osteoprotegerin Level With Myocardial Injury and Cardiovascular Calcification in Chronic Kidney Disease Patients

Background

Chronic kidney disease has emerged as a significant independent risk factor for cardiovascular disease. Cardiovascular calcification is an active process involving a complex interaction of inducers and inhibitors. High sensitivity cardiac troponin T assay detects troponin T with higher sensitivity and precision at an earlier point of time than the conventional assays, and is associated with poor outcomes. Serum osteoprotegerin is classed as an inhibitory factor for cardiovascular calcification. It is involved in the pathological processes of vascular damage and linked to the excess cardiovascular morbidity. The aim of the present study was to evaluate the extent of cardiovascular calcification and serum high sensitivity cardiac troponin T level, and their association with serum osteoprotegerin level in patients with chronic kidney disease stages 3-5.

Methods

90 chronic kidney disease patients were enrolled in this study, and they were divided into two groups: group (1) included 45 non-dialysis-dependent chronic kidney disease patients (stages 3-5) and group (2) included 45 chronic hemodialysis patients. Each group further subdivided according to the presence of cardiovascular calcification into subgroup A and B. Vascular calcifications were assessed by lateral lumbar, pelvis and hands X-ray radiographs. Valvular calcification was assessed by echocardiography. Serum cardiac troponin T was measured by high sensitivity assay and serum osteoprotegerin was measured by ELISA.

Results

Cardiovascular calcification distribution was 22.2% in group (1) and 33.3% in group (2). Serum osteoprotegerin and troponin T in calcification groups (1A and 2A) were significantly higher than non-calcification groups (1B and 2B; P < 0.001). Osteoprotegerin correlated positively with high sensitivity cardiac troponin T (rs = 0.72, P < 0.001). cardiovascular calcification correlated positively with osteoprotegerin, troponin T, and phosphorus. osteoprotegerin and phosphorus were significant independent predictors of cardiovascular calcification at cut-off values ≥4.6 ng/L and ≥6.95 mg/dl, respectively (P < 0.001). Serum phosphorus and creatinine were independent predictors of osteoprotegerin (P < 0.001 and 0.048, respectively).

Conclusion

Osteoprotegerin is strongly associated with cardiovascular calcification and high sensitivity cardiac troponin T. In addition, there is a positive association between calcification and troponin T. This suggests a role for osteoprotegerin in the pathogenesis and risk stratification of cardiovascular calcification and myocardial injury in chronic kidney disease patients with a potential role as a therapeutic target.

The pathogenic role of coronary microvascular dysfunction in the setting of other cardiac or systemic conditions

Coronary microvascular dysfunction (CMD) plays a pathogenic role in cardiac and systemic conditions other than microvascular angina. In this review, we provide an overview of the pathogenic role of CMD in the setting of diabetes mellitus, obesity, hypertensive pregnancy disorders, chronic inflammatory and autoimmune rheumatic disorders, chronic kidney disease, hypertrophic cardiomyopathy, and aortic valve stenosis. In these various conditions, CMD results from different structural, functional, and/or dynamic alterations in the coronary microcirculation associated with the primary disease process. CMD is often detectable very early in the course of the primary disease, before clinical symptoms or signs of myocardial ischaemia are present, and it portrays an increased risk for cardiovascular events.

Low magnesium diet aggravates phosphate-induced kidney injury

BACKGROUND

Magnesium is known to protect against phosphate-induced tubular cell injuries in vitro. We investigated in vivo effects of magnesium on kidney injuries and phosphate metabolism in mice exposed to a high phosphate diet.

METHODS

Heminephrectomized mice were maintained on a high phosphate/normal magnesium diet or a high phosphate/low magnesium diet for 6 weeks. We compared renal histology, phosphaturic hormones and renal α-Klotho expression between the two diet groups.

RESULTS

High phosphate diet-induced tubular injuries and interstitial fibrosis were remarkably aggravated by the low-magnesium diet. At 1 week after high phosphate feeding when serum creatinine levels were similar between the two groups, the low magnesium diet suppressed not only fecal phosphate excretion but also urinary phosphate excretion, resulting in increased serum phosphate levels. Parathyroid hormone (PTH) levels were not appropriately elevated in the low magnesium diet group despite lower 1,25-dihydroxyvitamin D and serum calcium levels compared with the normal magnesium diet group. Although fibroblast growth factor 23 (FGF23) levels were lower in the low magnesium diet group, calcitriol-induced upregulation of FGF23 could not restore the impaired urinary phosphate excretion. The low magnesium diet markedly downregulated α-Klotho expression in the kidney. This downregulation of α-Klotho occurred even when mice were fed the low phosphate diet.

CONCLUSIONS

A low magnesium diet aggravated high phosphate diet-induced kidney injuries. Impaired PTH secretion and downregulation of renal α-Klotho were likely to be involved in the blunted urinary phosphate excretion by the low magnesium diet. Increasing dietary magnesium may be useful to attenuate phosphate-induced kidney injury.

Impaired coronary microcirculation is associated with left ventricular diastolic dysfunction in end-stage chronic kidney disease patients

INTRODUCTION

Coronary vascular dysfunction, as assessed by coronary flow reserve (CFR) in the left anterior descending coronary artery, is found in various conditions including end-stage chronic kidney disease (CKD). Currently, we investigated the associations of CFR with echocardiographic indices of systolic and diastolic cardiac function and identified independent predictors of CFR in hemodialysis patients.

METHODS

End-stage CKD patients treated with hemodialysis (n = 29) without known cardiovascular disease were recruited from a Hemodialysis Unit in Northwestern Greece. A thorough echocardiographic evaluation including CFR measurement following dipyridamole infusion was performed in all participants. Arterial stiffness was assessed by measurement of carotid-femoral pulse wave velocity and aortic augmentation index.

RESULTS

The mean age of the patients was 63 years, and mean duration of hemodialysis was 2.9 years. CFR was 1.60 ± 0.37 while dipyridamole caused a significant increase in E'_sep , S_lat , E'_lat , and Stroke volume (P < .05 for all). Independent predictors of CFR were posterior wall thickness (B -0.408, P = .013) and dipyridamole-induced changes in Tei index (B -0.425, P = .007). A severely decreased CFR < 1.5 was observed in 52% of the patients. E/E' ratio (B 10.84, P = .014) was the single independent predictor of severely decreased CFR.

CONCLUSIONS

In end-stage CKD patients on hemodialysis without known cardiovascular disease, impaired coronary vascular function was prevalent and related to increased left ventricular wall thickness, increased filling pressures, and dipyridamole-induced deteriorated myocardial function independently of the presence of wall-motion abnormalities. Further studies are required to clarify the prognostic role of dipyridamole-induced cardiac changes in hemodialysis patients.

A Randomized Trial of Magnesium Oxide and Oral Carbon Adsorbent for Coronary Artery Calcification in Predialysis CKD

BACKGROUND

Developing strategies for managing coronary artery calcification (CAC) in patients with CKD is an important clinical challenge. Experimental studies have demonstrated that magnesium inhibits vascular calcification, whereas the uremic toxin indoxyl sulfate aggravates it.

METHODS

To assess the efficacy of magnesium oxide (MgO) and/or the oral carbon adsorbent AST-120 for slowing CAC progression in CKD, we conducted a 2-year, open-label, randomized, controlled trial, enrolling patients with stage 3-4 CKD with risk factors for CAC (diabetes mellitus, history of cardiovascular disease, high LDL cholesterol, or smoking). Using a two-by-two factorial design, we randomly assigned patients to an MgO group or a control group, and to an AST-120 group or a control group. The primary outcome was percentage change in CAC score.

RESULTS

We terminated the study prematurely after an interim analysis with the first 125 enrolled patients (of whom 96 completed the study) showed that the median change in CAC score was significantly smaller for MgO versus control (11.3% versus 39.5%). The proportion of patients with an annualized percentage change in CAC score of ≥15% was also significantly lower for MgO compared with control (23.9% versus 62.0%). However, MgO did not suppress the progression of thoracic aorta calcification. The MgO group's dropout rate was higher than that of the control group (27% versus 17%), primarily due to diarrhea. The percentage change in CAC score did not differ significantly between the AST-120 and control groups.

CONCLUSIONS

MgO, but not AST-120, appears to be effective in slowing CAC progression. Larger-scale trials are warranted to confirm these findings.

Characteristics of coronary artery disease in chronic kidney disease

Patients with chronic kidney disease (CKD) commonly experience cardiovascular disease (CVD), and a major cause of death in these patients is CVD. Therefore, the prevention of CVD progression is very crucial in patients with CKD. Recently, this relationship between CKD and CVD has increasingly been examined, and a concept termed “cardiorenal syndrome” has been advocated. Coronary artery disease (CAD) and myocardial injury are crucial factors that contribute to the occurrence of CVD. The initial step CAD is endothelial dysfunction that can be detected as a decrease in the coronary flow reserve (CFR). The previous studies have reported that decreased CFR is significantly correlated to coronary events and mortality. Furthermore, CFR reduces with a decline in the kidney function. Another important presentation of CAD is coronary artery calcification. Vascular calcification is a crucial pathophysiological state, particularly in patients with CKD, and it affects the stability of coronary atherosclerotic plaque. In CKD, not only the traditional risk factors but also CKD-related non-traditional risk factors play key roles in CVD progression. Therefore, the mechanisms responsible for CVD progression are very complex; however, their clarification is crucial to improve the prognosis in patients with CKD.

Effects of Rituximab on Atherosclerotic Biomarkers in Kidney Transplant Recipients

INTRODUCTION

Cardiovascular disease is the leading cause of mortality in kidney transplant recipients. Rituximab is widely used in kidney transplantation for a variety of situations, and rituximab may inhibit some cytokines and antibodies that may play an active role in the atherosclerotic process. The aim of the study was to evaluate the efficacy of rituximab on atherosclerosis biomarkers in kidney transplant recipients.

METHODS

All patients, 18 years of age and older, who underwent kidney transplantation and received at least 1 dose of 375 mg/m² rituximab were considered for participation in this study. The primary study endpoint was the development of cardiovascular diseases after rituximab therapy. The secondary endpoint was the onset of cytomegalovirus (CMV) disease or biopsy-confirmed BK virus nephropathy. In addition, comparison of atherosclerosis biomarkers was performed between study and control groups.

RESULTS

There were no cardiovascular events observed during follow up. Only 8 patients in the study group suffered from CMV disease during follow up. Serum interleukin 10 levels were significantly higher in the rituximab group compared with the control group, although anti-oxidized low-density lipoprotein levels were lower in the rituximab group compared with the control group, though this did not achieve statistical significance.

DISCUSSION

Rituximab treatment may increase the risk of CMV reactivation and decrease lymphocyte counts and interleukin 10 levels; however, significant decreases in all atherosclerotic-related biomarkers have not been shown in our study.

Effects of Lanthanum Carbonate on Coronary Artery Calcification and Cardiac Abnormalities After Initiating Hemodialysis

It is known that calcium-containing phosphate binders are more closely associated with the progression of vascular calcification than non-calcium-containing phosphate binders. In this study, we investigated the effect of the non-calcium-containing phosphate binder, lanthanum carbonate on the progression of coronary artery calcification and cardiovascular abnormalities compared to that of calcium-containing phosphate binder in chronic kidney disease patients during the early period after initiating hemodialysis. This was a randomized open-label study in which patients were divided into the calcium carbonate or lanthanum carbonate group. We evaluated blood samples, coronary artery calcification using high-resolution computed tomography, and cardiac abnormalities using echocardiography prior to and after initiating hemodialysis. Cardiac dimension and systolic function were significantly improved in the lanthanum carbonate group compared to those in the calcium carbonate group. Although statistically significant differences were not observed in all the patients, only among patients with moderate coronary artery calcification, the changes in coronary artery calcification score at 18 months were significantly smaller in the lanthanum carbonate group than those in the calcium carbonate group. The percent change in coronary artery calcification at 18 months was significantly correlated with the serum fibroblast growth factor 23 levels at 18 months (r = 0.245, P < 0.05). This significant correlation was particularly strong in patients with moderate coronary artery calcification (r = 0.593, P < 0.001). Our study suggests that lanthanum carbonate ameliorates cardiac abnormalities, and may slow coronary artery calcification development in patients with moderate coronary artery calcification, during the early period following hemodialysis initiation.

Normal body mass index with central obesity has increased risk of coronary artery calcification in Korean patients with chronic kidney disease

In chronic kidney disease (CKD), overweight and mild obesity have shown the lowest cardiovascular (CV) risk. However, central obesity has been directly associated with CV risk in these patients. This bidirectional relationship of body mass index (BMI) and central obesity prompted us to evaluate CV risk based on a combination of BMI and waist-to-hip ratio (WHR) in nondialysis CKD patients. We included 1078 patients with CKD stage 2 through 5 (nondialysis) enrolled in a nationwide prospective cohort of Korea. Patients were divided into 3 groups by BMI (normal BMI, 18.5-22.9; overweight, 23.0-27.4; and obese, 27.5 and over kg/m²) and were dichotomized by a sex-specific median WHR (0.92 in males and 0.88 in females). Coronary artery calcification (CAC) was determined by multislice computed tomography. CAC (score above 10 Agatston units) was found in 477 patients. Multivariate logistic regression analysis indicated that BMI was not independently associated with CAC. However, WHR showed an independent linear and significant association with CAC (odds ratio, 1.036; 95% confidence interval, 1.007-1.065 per 0.01 increase). Furthermore, when patients were categorized into 6 groups according to a combination of BMI and WHR, normal BMI but higher WHR had the highest risk of CAC compared with the normal BMI with lower WHR group (2.104; 1.074-4.121). Thus, a normal BMI with central obesity was associated with the highest risk of CAC, suggesting that considering BMI and WHR, 2 surrogates of obesity, can help to discriminate CV risk in Korean nondialysis CKD patients.

Relationship between serum osteoprotegerin and vascular calcifications in hemodialysis patients

BACKGROUND

Uremia is a vasculopathic process, and both cardiac calcification and vascular calcification seen from the early stages of chronic kidney disease. Osteoprotegerin could play a crucial role in atherosclerotic plaque formation, maturation and calcification. The goal of this study was to determine the relationship of serum osteoprotegerin with vascular calcification in patients with end stage kidney disease who were maintained on regular hemodialysis.

METHODS

Sixty clinically stable chronic renal failure patients undergoing regular hemodialysis were enrolled in this cross sectional study. Thirty patients (mean age 56.7 ± 10.5 years) with abdominal aortic calcification were selected by basal abdominal X-ray who underwent multi-slice computerized tomography scan to measure coronary artery calcification score; and thirty patients (mean age 56.5 ± 8.4 years) without abdominal aortic calcification. All patients were evaluated by serum calcium, phosphorus, albumin, lipid profile, intact parathyroid hormone (iPTH), serum creatinine, serum urea, serum uric acid, serum C-reactive protein, and hemoglobin. Serum osteoprotegerin samples were collected before dialysis and estimated by the ELISA kit.

RESULTS

Serum osteoprotegerin level was significantly higher in patients with vascular calcification than in those without calcifications. Serum osteoprotegerin correlated positively with serum phosphorus, calcium phosphorus product, alkaline phosphatase, iPTH, C-reactive protein, serum uric acid, low-density lipoprotein (LDL) and left ventricular mass index (LVMI) (p < 0.005), and negatively with hemoglobin, ejection fraction (p < 0.005) and HDL (p < 0.05).

CONCLUSIONS

These findings suggest that osteoprotegerin may be involved in the development of vascular calcification in hemodialysis patients.

Relationship between cardiac calcification and left ventricular hypertrophy in patients with chronic kidney disease at hemodialysis initiation

Coronary artery calcification (CAC), cardiac valve calcification (CVC) and left ventricular hypertrophy (LVH) are frequently observed in chronic kidney disease (CKD) patients. These abnormalities significantly affect morbidity and mortality. The aim of this study was to investigate the relationship between CAC, CVC and LVH in CKD patients. This study included 96 patients who were hospitalized and initiated hemodialysis between December 2011 and July 2014 at our five institutions. Multi-detector computed tomography for the quantification of CAC using the Agatston score and transthoracic echocardiography for assessing CVC and LVH were performed for all patients included in the study. We semi-quantitatively evaluated the severity of CVC as a valvular calcification score. We also assessed the presence of LVH in patients with CAC and/or CVC. Among the 96 patients, the prevalence of CAC was 81.3% and CVC was 65.0%. The severity of CAC was closely and significantly associated with that of CVC. The percentage of patients with LVH was the greatest in those with both severe CAC and CVC. CAC was significantly more severe in patients with concentric hypertrophy compared to those with normal geometry. At the initiation of hemodialysis, most CKD patients had CAC, CVC and LVH. In addition, cardiac calcification was significantly associated with LVH in these patients.

Association between Density of Coronary Artery Calcification and Serum Magnesium Levels among Patients with Chronic Kidney Disease

Background

The Agatston score, commonly used to quantify coronary artery calcification (CAC), is determined by the plaque area and density. Despite an excellent predictability of the Agatston score for cardiovascular events, the density of CAC has never been studied in patients with pre-dialysis chronic kidney disease (CKD). This study aimed to analyze the CAC density and its association with serum mineral levels in CKD.

Methods

We enrolled patients with pre-dialysis CKD who had diabetes mellitus, prior cardiovascular disease history, elevated low-density lipoprotein cholesterol levels, or smoking history. The average CAC density was calculated by dividing the Agatston score by the total area of CAC.

Results

The mean estimated glomerular filtration rate (eGFR) of 109 enrolled patients was 35.7 mL/min/1.73 m². The correlation of the Agatston score with density was much weaker than that with the total area (R² = 0.19, P < 0.001; and R² = 0.99, P < 0.001, respectively). Multivariate analyses showed that serum magnesium level was inversely associated with the density, but not with the total area, after adjustment for demographics and clinical factors related to malnutrition-inflammation-atherosclerosis syndrome and mineral and bone disorders including fibroblast growth factor 23 (P = 0.006). This inverse association was pronounced among patients with higher serum phosphate levels (P for interaction = 0.02).

Conclusion

CAC density was inversely associated with serum magnesium levels, particularly in patients with higher serum phosphate levels.

Coronary artery calcification, cardiovascular events, and death: a prospective cohort study of incident patients on hemodialysis

Background

Coronary calcification in patients with end-stage renal disease (ESRD) is associated with an increased risk of cardiovascular outcomes and death from all causes. Previous evidence has been limited by short follow-up periods and inclusion of a heterogeneous cluster of events in the primary analyses.

Objective

To describe coronary calcification in patients incident to ESRD, and to identify whether calcification predicts vascular events or death.

Design

Prospective substudy of an inception cohort.

Setting

Tertiary care haemodialysis centre in Ontario (St Joseph’s Healthcare Hamilton).

Participants

Patients starting haemodialysis who were new to ESRD.

Measurements

At baseline, clinical characterization and spiral computed tomography (CT) to score coronary calcification by the Agatston-Janowitz 130 scoring method. A primary outcome composite of adjudicated stroke, myocardial infarction, or death.

Methods

We followed patients prospectively to identify the relationship between cardiac calcification and subsequent stroke, myocardial infarction, or death, using Cox regression.

Results

We recruited 248 patients in 3 centres to our main study, which required only biochemical markers. Of these 164 were at St Joseph’s healthcare, and eligible to participate in the substudy; of these, 51 completed CT scanning (31 %). Median follow up was 26 months (Q₁, Q₃: 14, 34). The primary outcome occurred in 16 patients; 11 in the group above the median and 5 in the group below (p = 0.086). There were 26 primary outcomes in 16 patients; 20 (77 %) events in the group above the coronary calcification median and 6 (23 %) in the group below (p = 0.006). There were 10 deaths; 8 in the group above the median compared with 2 in the group below (p = 0.04). The hazard ratios for coronary calcification above, compared with below the median, for the primary outcome composite were 2.5 (95 % CI 0.87, 7.3; p = 0.09) and 1.7 (95 % CI 0.55, 5.4; p = 0.4), unadjusted and adjusted for age, respectively. For death, the hazard ratios were 4.6 (95 % CI 0.98, 21.96; p = 0.054) and 2.4 (95 % CI 0.45, 12.97; p = 0.3) respectively.

Limitations

We were limited by a small sample size and a small number of events.

Conclusions

Respondent burden is high for additional testing around the initiation of dialysis. High coronary calcification in patients new to ESRD has a tendency to predict cardiovascular outcomes and death, though effects are attenuated when adjusted for age.

Use of vitamin D receptor activator, incident cardiovascular disease and death in a cohort of hemodialysis patients

The use of vitamin D receptor activators (VDRAs) is an independent predictor of a lower risk of death from cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). We examined whether the use of VDRAs and other CKD-mineral bone disorder (MBD)-related factors are associated with incident CVD or death after CVD in hemodialysis patients. This is a historical cohort study of 37 690 prevalent hemodialysis patients without previous history of CVD at the end of 2004 extracted from a nationwide registry in Japan. The key exposure was the use of VDRAs, and the outcomes were incident CVD (myocardial infarction, cerebral infarction, cerebral hemorrhage, and sudden death) and death after CVD during the 1-year follow-up. VDRAs were used in 57% of the subjects at baseline. We identified 2433 patients with incident CVD and 397 deaths after the events. In multivariate logistic regression models, independent predictors of incident CVD were non-use of VDRA, higher intact PTH, non-use of calcium-based phosphate-binder, and non-use of non-calcium-based phosphate binder. Risk of death after CVD was not significantly associated with VDRA, whereas it was lower in those with lower corrected calcium, and the risk was higher in those with higher phosphate and in non-users of calcium-based phosphate binders. The use of VDRAs was associated with a lower risk of incident CVD but not with death after CVD in this large cohort of hemodialysis patients. The CKD-MBD-related predictors of poor outcomes are associated with the risk of incident CVD, the risk of death after CVD, or both.

An update on coronary artery disease and chronic kidney disease

Despite the improvements in diagnostic tools and medical applications, cardiovascular diseases (CVD), especially coronary artery disease (CAD), remain the most common cause of morbidity and mortality in patients with chronic kidney disease (CKD). The main factors for the heightened risk in this population, beside advanced age and a high proportion of diabetes and hypertension, are malnutrition, chronic inflammation, accelerated atherosclerosis, endothelial dysfunction, coronary artery calcification, left ventricular structural and functional abnormalities, and bone mineral disorders. Chronic kidney disease is now recognized as an independent risk factor for CAD. In community-based studies, decreased glomerular filtration rate (GFR) and proteinuria were both found to be independently associated with CAD. This paper will discuss classical and recent epidemiologic, pathophysiologic, and clinical aspects of CAD in CKD patients.

Relation of albuminuria to coronary microvascular function in patients with chronic kidney disease

The relation between albuminuria and coronary microvascular function in patients with chronic kidney disease (CKD) has not been fully investigated. Therefore, we sought to assess whether albuminuria is associated with coronary flow velocity reserve (CFVR) impairment in patients with CKD. Coronary flow study was prospectively performed in 175 patients with CKD. CFVR of the left anterior descending artery was measured to evaluate coronary microvascular function using transthoracic echocardiography. We divided the patients into 5 groups according to the stages of CKD and analyzed the effect of albuminuria. CFVR gradually decreased with an increase in CKD stages. CFVR in patients with albuminuria was lower than those without albuminuria. In groups with CKD stages 2 and 3, the patients with albuminuria showed lower CFVR than those without albuminuria. Multiple logistic regression analysis revealed that albuminuria, age, and gender were independently associated with CFVR impairment. Of these factors, albuminuria was the most powerful predictor with the risk ratio of 12.4 for CFVR impairment. In conclusion, the more the CKD stages progressed, the more severe CFVR was impaired. Albuminuria was associated with CFVR impairment in patients with CKD; even in mild-to-moderate CKD, patients with albuminuria showed further reduced coronary vasodilator capacity.

Decreased serum selenium levels are correlated with diminished coronary flow reserve among hemodialysis patients

Cardiovascular diseases are the main reason of high mortality among hemodialysis patients. Decreased serum selenium levels may have a role in accelerated atherosclerosis in this patient group. The hypothesis of this study was to show a correlation between decreased serum selenium levels and coronary flow reserve as an indicator of endothelial dysfunction and atherosclerosis in HD patients. Seventy-one chronic hemodialysis patients and age 65 and sex-matched healthy controls were included in the study. Plasma selenium levels were measured by spectrophotometry, and coronary flow reserve was assessed by transthoracic Doppler echocardiography. Serum selenium levels (34.16 ± 6.15 ng/ml vs. 52.4 ± 5.51 ng/ml, P < 0.001) and coronary flow reserve values (1.73 ± 0.11 vs. 2.32 ± 0.28, P < 0.001) were significantly lower in hemodialysis patients compared with controls, respectively. There was a significant positive correlation between coronary flow reserve and serum levels of selenium (r = 0.676, P < 0.001). A linear regression analysis showed that serum levels of selenium were independently and positively correlated with coronary flow reserve (regression coefficient = 0.650, P < 0.05). This study was the first to show a positive and independent correlation between decreased selenium levels and diminished coronary flow reserve as an indicator of endothelial dysfunction and atherosclerosis in hemodialysis patients. Our data suggest that decreased serum selenium levels may facilitate the development of endothelial dysfunction and disruption of coronary flow reserve which occur before the development of overt atherosclerosis.

FGF-23 associated with the progression of coronary artery calcification in hemodialysis patients

BACKGROUND

Disordered mineral metabolism is implicated in the pathogenesis of vascular calcification in hemodialysis (HD) patients. Fibroblast growth factor 23 (FGF-23) is the main regulator of phosphate metabolism. In this prospective study, we aimed to investigate the association of serum FGF-23 with progression of coronary artery calcification in HD patients.

METHODS

Seventy-four HD patients (36 male/38 female, mean age: 52 ± 14 years) were included. Serum FGF-23 levels were measured by ELISA. Coronary artery calcification score (CACS) was measured twice with one year interval. Patients were grouped as progressive (PG) (36 patients-48%) and non-progressive (NPG).

RESULTS

Age, serum phosphorus, baseline and first year CACS were found to be significantly higher in the PG compared to NPG group. Serum FGF-23 levels were significantly higher in PG [155 (80-468) vs 147 (82-234), p = 0.04]. Patients were divided into two groups according to baseline CACS (low group, CACS ≤ 30; high group, CACS > 30). Serum FGF-23 levels were significantly correlated with the progression of CACS (ΔCACS) in the low baseline CACS group (r = 0.51, p = 0.006), but this association was not found in high baseline CACS group (r = 0.11, p = 0.44). In logistic regression analysis for predicting the PG patients; serum FGF-23, phosphorus levels and baseline CACS were retained as significant factors in the model.

CONCLUSIONS

Serum FGF-23 was found to be related to progression of CACS independent of serum phosphorus levels. FGF-23 may play a major role in the progression of vascular calcification especially at the early stages of calcification process in HD patients.

Effect of serum FGF-23, MGP and fetuin-A on calcium-phosphate metabolism in maintenance hemodialysis patients

This study was aimed to explore the role of serum fibroblast growth factor (FGF)-23, matrix Gla protein (MGP) and fetuin-A in the calcium-phosphate metabolism and their predicting value in coronary artery calcification in maintenance hemodialysis (MHD) patients. This study included 64 patients who receive hemodialysis in our hospital. The serum FGF-23, MGP and fetuin-A were analyzed by enzyme-linked immunosorbent assay (ELlSA). Coronary artery calcification score (CACS) was evaluated by coronary artery computed tomography scan. The 64 patients (30 males, 34 females, 60.6 ± 11.3 years of age) received an average dialysis vintage of 6.88 ± 2.94 years. We divided the CACS into three levels, and 13 (20.31%), 16 (25%), and 35 (54.69%) exhibited a CACS of 0-100, 100-400, and >400, respectively. Dialysis vintage, serum FGF-23, fetuin-A, phosphorus and high-density lipoprotein-C levels were identified as independent variables of CACS by stepwise multiple regression analysis. The area under receiver operating characteristic curve indicated that serum FGF-23 and fetuin-A were useful for identifying CAC in MHD patients. The cut-off value corresponding to the highest Youden's index was serum FGF-23 ≥ 256 pg/mL and fetuin-A ≤ 85 μg/mL, which was defined as the optimal predictors of CAC. Different combinations of serum FGF-23 and fetuin-A in parallel or in series effectively boosted the identification of CAC. The incidence of CAC is high in MHD patients. Serum FGF-23 and fetuin-A levels are closely correlated with CAC.

Serum coenzyme Q10 levels are associated with coronary flow reserve in hemodialysis patients

Accelerated atherosclerosis is the major cause of mortality in patients on chronic hemodialysis (HD). The aim of this study was to evaluate the relation between coenzyme Q10 (CoQ10) levels and coronary flow reserve (CFR) in HD patients as an indicator of atherosclerosis. Seventy-one chronic HD patients and 65 age- and sex-matched healthy individuals were included in the study. Plasma CoQ10 levels were performed by high-performance liquid chromatography measurements. CFR was assessed by transthoracic Doppler echocardiography. Serum CoQ10 levels (1.36 ± 0.43 vs. 2.53 ± 0.55, P < 0.001) and CFR values (1.73 ± 0.11 vs. 2.32 ± 0.28, P < 0.001) were significantly lower in HD patients compared with controls. There was a significant positive correlation between CFR and serum levels of CoQ10 (r = 0.669, P < 0.001). A linear regression analysis showed that serum levels of CoQ10 were still significantly and positively correlated with CFR (regression coefficient = 0.235, P < 0.001). Our data have demonstrated that HD patients exhibit decreased plasma CoQ10 levels and CFR values. The study also showed for the first time that serum CoQ10 levels independently predict CFR in HD patients.

Epicardial adipose tissue volume and cardiovascular disease in hemodialysis patients

OBJECTIVE

Epicardial adipose tissue (EAT) is proposed as a cardiovascular risk marker in non-uremic subjects. However, little is known about its role in patients with higher cardiovascular risk profile such as chronic kidney disease. The aim of this study was to investigate the relationship between EAT and several cardiovascular surrogate markers (coronary artery calcification (CAC), arterial stiffness and atherosclerosis) in patients on maintenance hemodialysis.

METHODS

A total of 191 prevalent hemodialysis patients were enrolled in this cross-sectional study. EAT and CAC scores (CACs) were determined by multi-slice computerized tomography, arterial stiffness by carotid-femoral pulse wave velocity (PWV), and carotid artery intima-media thickness (CA-IMT) by B-mode doppler ultrasonography.

RESULTS

Mean age was 59 ± 13 years and time on hemodialysis 75 ± 44 months. Twenty percent of the patients had diabetes. Mean EAT volume was 62.6 ± 26.8 cm(3)/m(2). Mean CA-IMT and PWV values increased across the EAT tertiles. EAT was correlated with age, female gender, body mass index, albumin and lipid parameters. Additionally, CA-IMT and PWV values were positively correlated with EAT. EAT volume was significantly higher in patients with CACs >10 compared to the patients with CACs ≤10. Despite the univariate associations between EAT and cardiovascular surrogate markers, only age, body mass index and total cholesterol levels were associated with EAT in adjusted models.

CONCLUSIONS

In prevalent hemodialysis patients, EAT is correlated with atherosclerosis, arterial stiffness and the presence of CAC. However, this correlation is not independent of other risk factors.

Composition and plaque patterns of coronary culprit lesions and clinical characteristics of patients with chronic kidney disease

Coronary artery disease is a serious complication of chronic kidney disease (CKD); however, there is little information about coronary plaque morphology in these patients. Here we identified the characteristics of coronary culprit plaques and their clinical manifestations in 78 patients with CKD divided into four groups based on their estimated glomerular filtration rate. Patients were examined by Virtual Histology-Intravascular Ultrasound, a tomographic imaging method that can visualize atherosclerotic plaques in vivo using radiofrequency analysis of ultrasound backscatter signals. These ultrasound analyses showed an increase in the relative volumes of both dense calcium and necrotic core with decreasing renal function. The necrotic core/dense calcium ratio was significantly higher in patients with acute myocardial infarction compared to those with stable angina pectoris. Furthermore, the necrotic core/dense calcium ratio decreased in advanced CKD. Thus, the plaque composition of coronary culprit lesions changed from necrotic core-rich to extensively calcium-rich plaques as renal function decreased, suggesting that such coronary culprit composition was associated with stability, particularly in advanced CKD.

Osteoprotegerin/RANKL axis and progression of coronary artery calcification in hemodialysis patients

BACKGROUND AND OBJECTIVES

Vascular calcification is associated with increased cardiovascular mortality in chronic hemodialysis patients. This prospective study investigated the relationship between serum osteoprotegerin, receptor activator of NF-κB ligand, inflammatory markers, and progression of coronary artery calcification score.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Seventy-eight hemodialysis patients were enrolled. Serum IL-1β, IL-6, TNF-α, osteoprotegerin, receptor activator of NF-κB, fetuin A, and bone alkaline phosphatase were measured by ELISA. Coronary artery calcification score was measured two times with 1-year intervals, and patients were classified as progressive or nonprogressive.

RESULTS

Baseline and first-year serum osteoprotegerin levels were significantly higher in the progressive than nonprogressive group (17.39±9.67 versus 12.90±6.59 pmol/L, P=0.02; 35.17±18.35 versus 24±11.65 pmol/L, P=0.002, respectively). The ratio of serum osteoprotegerin to receptor activator of NF-κB ligand at 1 year was significantly higher in the progressive group (0.26 [0.15-0.46] versus 0.18 [0.12-0.28], P=0.004). Serum osteoprotegerin levels were significantly correlated with coronary artery calcification score at both baseline (r=0.36, P=0.001) and 1 year (r=0.36, P=0.001). Importantly, progression in coronary artery calcification score significantly correlated with change in serum osteoprotegerin levels (r=0.39, P=0.001). In addition, serum receptor activator of NF-κB ligand levels were significantly inversely correlated with coronary artery calcification scores at both baseline (r=-0.29, P=0.01) and 1 year (r=-0.29, P=0.001). In linear regression analysis for predicting coronary artery calcification score progression, only baseline coronary artery calcification score and change in osteoprotegerin were retained as significant factors in the model.

CONCLUSIONS

Baseline coronary artery calcification score and serum osteoprotegerin levels were significantly associated with progression of coronary artery calcification score in hemodialysis patients.

The Relationship between Epicardial Adipose Tissue and Coronary Artery Calcification in Peritoneal Dialysis Patients

BACKGROUND: Atherosclerosis, endothelial dysfunction, coronary artery calcification (CAC), and left ventricular hypertrophy are the most commonly encountered risk factors in the pathogenesis of cardiovascular disease in end-stage renal disease patients. Epicardial adipose tissue (EAT) is the true visceral fat depot of the heart. The relationship between coronary artery disease and EAT has been shown in healthy subjects and patients with a high risk of coronary artery disease. In the present study, we aimed to investigate the relationship between EAT and CAC in peritoneal dialysis (PD) patients. Patients and Methods: Forty-five PD patients (18 females, 27 males, with a mean age of 50.6 ± 15 years) and 25 healthy subjects (12 females, 13 males, with a mean age of 52.4 ± 10.7 years) were enrolled in the study. EAT and CAC score (CACS) measurements were performed by a multidetector computed tomography scanner. RESULTS: EAT of the PD patients was significantly higher than that of the healthy subjects (p = 0.02). When patients were divided into two subgroups (group 1: CACS ≤10, n = 20; group 2: CACS >10, n = 25), EAT was also significantly higher in group 2 patients than in group 1 patients and healthy subjects. Age and EAT were also found to be correlated with CACS ≥10. CONCLUSION: There is a relationship between the anatomic assessment of coronary artery lesions by multidetector computed tomography and EAT in PD patients. This relationship might be attributed to increased inflammation and proinflammatory cytokines in uremic patients.

Fetuin-A, inflammation, and coronary artery calcification in hemodialysis patients

Hemodialysis patients have extremely increased cardiovascular mortality. Vascular calcification, inflammation, and low serum fetuin-A levels are implicated for increased mortality. In this study, relationship between coronary artery calcification, inflammation, and serum fetuin-A levels were investigated. Seventy-eight hemodialysis patients (38 male, 40 female, mean age: 52±14.5 years) were included. All patients were on dialysis for more than 6 months. Coronary artery calcium scores (CACS) are determined by electron-beam computed tomography. Serum CRP, IL-1β, IL-6, TNF-α, and serum fetuin-A levels were measured. Mean CACS value was 488.5±94.5. Serum fetuin-A levels were negatively correlated with CACS (r:–0.30, P=0.009). Patients are divided into two groups according to total CACS value; group 1 (CACS<10), group 2 (CACS≥10). There was a statistically significance difference in fetuin-A levels between CACS group 1 and group 2 (P=0.001). In this study, serum fetuin-A levels were associated with total CACS. This Fetuin-A may play a role in increased mortality in this group of patients via facilitating CAC.

The relationship between epicardial adipose tissue and malnutrition, inflammation, atherosclerosis/calcification syndrome in ESRD patients

BACKGROUND AND OBJECTIVES

Malnutrition, inflammation, atherosclerosis/calcification (MIAC) and endothelial dysfunction are the most commonly encountered risk factors in the pathogenesis of cardiovascular disease in ESRD patients. Epicardial adipose tissue (EAT) is the true visceral fat depot of the heart. The relationship between CAD and EAT was shown in patients with high risk of coronary artery disease. In this study, we aimed to investigate the relationship between EAT and MIAC syndrome in ESRD patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Eighty ESRD patients and 27 healthy subjects enrolled in this cross-sectional study. EAT and coronary artery calcification score were measured by a multidetector computed tomography (MDCT) scanner. Patients with serum albumin <3.5 mg/dl were defined as patients with malnutrition; those with serum C-reactive protein level >10 ng/dl (normal range, 0-5 ng/dl) had inflammation; and those with CACS >10 had atheroscleosis/calcification.

RESULTS

Total CACS and EAT measurements were significantly higher in ESRD patients when compared with healthy subjects. There was a statistically significant relationship between EAT and CACS in ESRD patients (r = 0.48). EAT measurements were higher in PD patients than HD patients. Twenty-four of the patients had no component, 31 had one component, 17 had two components, and nine had all of the MIAC components. EAT was found to be significantly increased when the presence of MIAC components increased. EAT was positively correlated with age, body mass index, and presence of MIAC. These parameters were also found as independent predictors of increased EAT.

CONCLUSIONS

We found a relationship between EAT and components of MIAC syndrome in ESRD patients.