Evolution of coronary artery calcifications following kidney transplantation: relationship with osteoprotegerin levels

Association of Serum Osteoprotegerin With Vascular Calcification, and Cardiovascular and Graft Outcomes in Kidney Transplant Patients: Results From the KNOW-KT

BACKGROUND

Vascular calcification and stiffness contribute to increased cardiovascular morbidity in patients with chronic kidney disease. This study investigated associations between serum osteoprotegerin (OPG) levels and vascular calcification or stiffness to assess cardiovascular and graft outcomes in kidney transplant patients.

METHODS

The KoreaN cohort study for Outcome in patients With Kidney Transplantation was a prospective multicenter cohort study. Serum OPG levels were measured at baseline and 3 y after transplantation in 1018 patients. Patients were classified into high and low OPG groups according to median serum OPG levels. The median follow-up duration was 93.5 mo.

RESULTS

The mean age was 45.8 ± 11.7 y and 62.9% were men. Patients with high OPG had significantly higher coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities than those with lower OPG; these parameters remained significant for 5 y after transplantation. The 3-y OPG levels were lower than baseline values ( P  < 0.001) and were positively correlated ( r  = 0.42, P  < 0.001). Multivariate Cox regression analysis showed that high OPG levels were significantly associated with posttransplant cardiovascular events ( P  = 0.008) and death-censored graft loss ( P  = 0.004). Similar findings regarding posttransplant cardiovascular events ( P  = 0.012) and death-censored graft loss ( P  = 0.037) were noted in patients with high OPG at the 3-y follow-up. Mediation analyses revealed that coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities could act as mediators between serum OPG levels and posttransplant cardiovascular events.

CONCLUSIONS

Serum OPG concentration is associated with vascular calcification and stiffness and could be a significant risk factor for cardiovascular outcomes and graft loss in patients undergoing kidney transplantation.

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.

Coronary artery calcification progression and long-term cardiovascular outcomes in renal transplant recipients: an analysis by the joint model

Background

Compared with the general population, the risk of death is substantially higher in renal transplant recipients than in age- and sex-matched individuals in the general population. In the general population, coronary artery calcification (CAC) predicts all-cause and cardiovascular mortality. In this study we aimed to analyse these relationships in renal transplant recipients.

Methods

We examined 178 renal transplant patients in this prospective observational cohort study. We measured CAC with multidetector spiral computed tomography using the Agatston score at multiple time points. Overall, 411 scans were performed in 178 patients over an average 12.8 years follow-up. The clinical endpoint was a composite including all-cause death and non-fatal cardiovascular events. Data analysis was performed by the joint model.

Results

During a follow-up of 12.8 ± 2.4 years, coronary calcification progressed over time (P < 0.001) and the clinical endpoint occurred in 54 patients. In the analysis by the joint model, both the baseline CAC score and the CAC score progression were strongly associated with the incidence rate of the composite event [hazard ratio 1.261 (95% confidence interval 1.119–1.420), P = 0.0001].

Conclusions

CAC at baseline and coronary calcification progression robustly predict the risk of death and cardiovascular events in renal transplant recipients. These findings support the hypothesis that the link between the calcifying arteriopathy of renal transplant patients and clinical end points in these patients is causal in nature.

Vascular Calcification in Chronic Kidney Disease: Distinct Features of Pathogenesis and Clinical Implication

Chronic kidney disease (CKD) is associated with a higher prevalence of vascular calcification (VC) and cardiovascular disease. VC in CKD patients showed different pathophysiological features from those of the general population. The pathogenesis of VC in CKD is a highly organized process, and prior studies have suggested that patients with CKD have their own specific contributors to the phenotypic change of vascular smooth muscle cells (VSMCs), including uremic toxins, CKD-mineral and bone disease (CKD-MBD), inflammation, and oxidative stress. For the diagnosis and monitoring of VC in CKD, several imaging modalities, including plain radiography, ultrasound, and computed tomography have been utilized. VC in CKD patients has distinct clinical features and implications. CKD patients revealed a more intense and more prevalent calcification on the intimal and medial layers, whereas intimal calcification is predominantly observed in the general population. While a higher VC score is clearly associated with a higher risk of all-cause mortality and cardiovascular events, a greater VC score in CKD patients does not fully reflect the burden of atherosclerosis, because they have more calcification at equal volumes of atheromatous plaques. The primary goal of VC treatment in CKD is the prevention of VC progression, and the main management is to control the biochemical components of CKD-MBD. Cinacalcet and non-calcium-containing phosphate binders are the mainstay of VC prevention in CKD-MBD management. VC in patients with CKD is an ongoing area of research and is expected to advance soon.

Serum Osteoprotegerin Is an Independent Marker of Metabolic Complications in Non-DialysisDependent Chronic Kidney Disease Patients

BACKGROUND

Osteoprotegerin (OPG) belongs to the tumour necrosis factor superfamily and is known to accelerate endothelial dysfunction and vascular calcification. OPG concentrations are elevated in patients with chronic kidney disease. The aim of this study was to investigate the association between OPG levels and frequent complications of chronic kidney disease (CKD) such as anaemia, protein energy wasting (PEW), inflammation, overhydration, hyperglycaemia and hypertension.

METHODS

One hundred non-dialysis-dependent men with CKD stage 3-5 were included in the study. Bioimpedance spectroscopy (BIS) was used to measure overhydration, fat amount and lean body mass. We also measured the serum concentrations of haemoglobin, albumin, total cholesterol, C-reactive protein (CRP), fibrinogen and glycated haemoglobin (HgbA1c), as well as blood pressure.

RESULTS

We observed a significant, positive correlation between OPG and age, serum creatinine, CRP, fibrinogen, HgbA1c concentrations, systolic blood pressure and overhydration. Negative correlations were observed between OPG and glomerular filtration rate (eGFR), serum albumin concentrations and serum haemoglobin level. Logistic regression models revealed that OPG is an independent marker of metabolic complications such as anaemia, PEW, inflammation and poor renal prognosis (including overhydration, uncontrolled diabetes and hypertension) in the studied population.

CONCLUSION

Our results suggest that OPG can be an independent marker of PEW, inflammation and vascular metabolic disturbances in patients with chronic kidney disease.

Hypercalcemia Is a Risk Factor for the Progression of Aortic Calcification in Kidney Transplant Recipients

BACKGROUND/AIMS

Vascular calcification is common and progressive in chronic kidney disease, including kidney transplant recipients (KTRs). However, the risk factors associated with the progression of aortic calcification (AoC) in KTRs have not been fully elucidated. In the present study, we evaluated AoC and examined the factors associated with its advancement in KTRs.

MATERIALS

This was a prospective longitudinal study that included 98 KTRs. We quantitatively investigated infrarenal abdominal AoC using the Agatston score, as measured by multi-slice computed tomography. After the baseline investigation, a follow-up scan was performed after 3 years, and the Agatston scores were obtained again. The changes in laboratory data affecting the 2nd Agatston scores were examined by multivariable analysis using non-linear regression after adjustment for several confounders.

RESULTS

The 2nd Agatston scores were significantly greater than the baseline Agatston scores (p < 0.001). After adjustment for the confounders, the change in corrected serum calcium exhibited a significant non-linear correlation with the 2nd Agatston scores (p = 0.022 for non-linearity/p = 0.031 for the effect of corrected serum calcium). Moreover, an interaction was present from the baseline AoC in the effect of corrected serum calcium on the progression of AoC, and the effect of hypercalcemia was greater in patients with higher baseline Agatston scores (p = 0.049).

CONCLUSION

The present study revealed that hypercalcemia is a risk factor for the development of infrarenal abdominal AoC in KTRs. Furthermore, the effect of hypercalcemia was greater in patients with more severe vascular calcification.

Prevalence of coronary artery calcification and its association with mortality, cardiovascular events in patients with chronic kidney disease: a systematic review and meta-analysis

PURPOSE

To date, the prevalence and prognostic role of coronary artery calcification (CAC) in patients with chronic kidney disease (CKD) have been investigated in several studies, but have yielded conflicting results. The aim of this meta-analysis is to derive a more precise estimation of CAC prevalence in CKD patients and its association with cardiovascular events and mortality.

METHODS

The relevant literature was identified and evaluated from inception until July 2018 through multiple search strategies on PubMed, Embase, and Web of Science. Cross-sectional or cohort (baseline data) studies reporting CAC prevalence were included. Data extracted from eligible studies were used to calculate effect estimates (ESs) and 95% confidence intervals (95%CI). We searched databases for observational studies that explored baseline CAC and subsequent cardiovascular or all-cause mortality risk in CKD patients.

RESULTS

The meta-analysis included 47 studies; 38 of these were included in the final analysis of CAC prevalence. The pooled prevalence of CAC in random effect model was 60% (95%CI 53-68%). CAC was positively associated with an increased risk of all-cause mortality (hazard ratio [HR] 3.44; 95%CI 2.40-4.94), cardiovascular mortality (HR 3.87; 95%CI 2.06-7.26), and cardiovascular events (HR 2.09; 95%CI 1.19-3.67), when comparing individuals in the top CAC score group to those in the bottom CAC score group.

CONCLUSIONS

The pooled prevalence of CAC is highly prevalent. CAC is independently associated with all-cause and cardiovascular mortality risk as well as cardiovascular events among CKD patients. In view of the high heterogeneity, larger clinical trials are still needed.

Long-term evaluation of coronary artery calcifications in kidney transplanted patients: a follow up of 5 years

Coronary artery calcifications(CACs), are related to the increased cardiovascular mortality during kidney transplantation(KTx). Using coronary-CT performed at 1 month(T0) and 5 years(T5) after KTx we evaluated: (1) the prevalence of CACs; (2) the clinical and biochemical factors related to CACs; 3) the factors implicated with CACs progression. We evaluated 67-pts selected from the 103-pts transplanted in our unit between 2007 and 2008. Clinical and biochemical parameters were recorded at the time of pre-KTx evaluation and for five years after KTx. Coronary-CT for the Agatson score (AS) evaluation was performed at T0 and at T5, and CACs progression was determined. At baseline AS was 45 [0–233]. At T5 AS was 119 [1–413]. At T0, 69% of patients had CACs. Age and dialytic vintage were the main independent variables related to CACs. At T5, CACs were present in 76% of patients. Age was the only independent factor in determining CACs. A progression of CACs was observed in 74% of patients. They were older, had higher CACs-T0 and higher SBP throughout the 5-years. The presence of CACs at T0 and age were the only independent factors in determining the CACs-progression. CACs-T0 had the best discriminative power for CACs progression. CACs prevalence is quite high in KTx patients; Age is strictly related to CACs; Age and the presence of CACs at baseline were the two major factors associated with the progression of CACs during the five years of follow up. CACs-T0 had the best discriminative power for progression of CACs.

Is progression of coronary artery calcification influenced by modality of renal replacement therapy? A systematic review

BACKGROUND

Progression of coronary artery calcification is an important marker for cardiovascular morbidity in end-stage renal disease patients. Therefore, we reviewed the evidence on coronary artery calcification progression in different renal replacement therapies.

METHODS

MEDLINE (PubMed), Embase and TRIP databases were searched from 1999 - 2016. Additionally, bibliographies were searched by hand and citation tracking of key publications was performed. Prospective studies were included that examined coronary artery calcification with two or more multislice computed tomography scans ≥6 months apart in patients 18-75 years old receiving any renal replacement therapy, including kidney transplantation. Reporting of separate scores for different modalities was required. Two researchers extracted data independently with pilot-tested forms and assessed the risk of bias using a validated tool.

RESULTS

We identified 29 eligible studies that assessed coronary artery calcification progression in end-stage renal disease patients, of which 19 studies evaluated haemodialysis and 8 kidney transplantation. Evidence on progression in peritoneal dialysis (three studies) and nocturnal haemodialysis (one study) was limited. Meta-analysis was not possible due to diverse reporting methods of coronary artery calcification scores and definitions of progression. Median coronary artery calcification scores were considerably higher in haemodialysis cohorts at baseline, presumably due to a generally higher age and dialysis vintage. Median coronary artery calcification progressed universally. Visual inspection suggested the least progression in kidney transplant recipients.

CONCLUSIONS

There is insufficient evidence to compare the influence of renal replacement therapies on coronary artery calcification progression. We advocate the adoption of a standardized reporting method of coronary artery calcification progression.

Prognostic value of bone- and vascular-derived molecular biomarkers in hemodialysis and renal transplant patients: a systematic review and meta-analysis

Background

Patients undergoing hemodialysis and kidney graft recipients are high-risk populations for cardiovascular and all-cause mortality. Fibroblast growth factor 23 (FGF23), osteoprotegerin (OPG), RANK ligand, osteopontin (OPN), Klotho protein and bone morphogenetic protein-7 (BMP-7) are bone- and vascular-derived molecular biomarkers that have been shown to be associated with cardiovascular surrogate end points; however, currently available data on the prognostic value of these biomarkers is inconsistent. The aim of the present study was to conduct a systematic review and meta-analysis in order to summarize the available evidence on the association of molecular biomarkers with mortality in individuals undergoing hemodialysis and renal transplant patients.

Methods

Two databases (MEDLINE and Embase) were systematically searched. Studies were eligible if the association of biomarker and mortality was reported as time-to-event data [hazard Ratio (HR)] or as effect size with a fixed time of follow-up [odds Ratio (OR)]. Abstracted HRs were converted onto a standard scale of effect and combined using a random effects model.

Results

From a total of 1170 studies identified in initial searches, 21 met the inclusion criteria. In hemodialysis patients, comparing the lower third with the upper third of baseline FGF23 distribution, pooled HRs (95% confidence intervals) were 1.94 (1.47, 2.56) for all-cause mortality and 2.4 (1.64, 3.51) for cardiovascular mortality. For the same comparison of baseline OPG distribution, pooled HRs were 1.8 (0.95, 3.39) for all-cause mortality and 2.53 (1.29, 4.94) for cardiovascular mortality. Reported risk estimates of RANK ligand, OPN, Klotho protein and BMP-7 were not suitable for pooling; however, only Klotho protein was significantly related to mortality. For kidney graft recipients, four studies that investigated the relationship of FGF23 and OPG with mortality were identified, all of which reported a significant association.

Conclusions

In hemodialysis patients, FGF23 is a predictor of all-cause and cardiovascular mortality, whereas the predictive value of OPG is restricted to cardiovascular mortality. Further studies are needed in order to gain insight into the prognostic value of these biomarkers in renal transplant recipients.

Cyclosporin A Aggravates Calcification of Vascular Smooth Muscle Cells Under High-Glucose Conditions with a Calcifying Medium

BACKGROUND Vascular calcification (VC) progresses substantially even after kidney transplantation, and is a predictor of morbidity and mortality. However, the effect of cyclosporin A (CsA) on VC has not been reported in diabetic kidney transplant patients. In this study, we evaluated the effect of CsA on the VC of mouse vascular smooth muscle cells (VSMCs) under high glucose (HG). MATERIAL AND METHODS To demonstrate the effect of CsA (1.0 µmol/L) and HG (30 mM) in the induction of the VC of the VSMCs, we determined alkaline phosphatase (ALP) activity, microscopic morphology of calcification, the expressions of the calcification and inflammation-related genes, and the intracellular calcium concentrations in VSMCs. RESULTS Calcification was observed 14 days after exposure to a calcifying medium (sodium phosphate monobasic and dibasic mixture). On microscopic morphology, CsA alone did not induce calcification under HG conditions, but clearly increased calcification under HG with a calcifying medium. ALP activity increased under HG with CsA or a calcifying medium compared to HG conditions alone. CsA increased ALP activity under low glucose (LG, 5.5 mM) with a calcifying medium, but markedly increased under HG with a calcifying medium. CsA significantly increased the mRNA expressions of the calcification markers (core binding factor-alpha 1, bone morphologic proteins 2) as well as those of the inflammatory marker (interleukin 6), under HG with a calcifying medium. Intracellular calcium concentrations were unchanged in CsA alone but significantly increased with the presence of a calcifying medium under both LG and HG conditions. CONCLUSIONS Considering the effect of CsA on VC, the vascular adverse effects of CsA need to be verified in diabetic transplant patients in the future.

Elevated serum osteoprotegerin may predict peripheral arterial disease after kidney transplantation: a single-center prospective cross-sectional study in Taiwan

Background

Osteoprotegerin (OPG) is a potential biomarker for severity and complications of cardiovascular diseases. Peripheral arterial disease (PAD) is associated with an increased risk of death in kidney transplantation (KT) patients. This prospective cross-sectional study evaluated the relationship between serum OPG and PAD in KT patients.

Methods

Seventy-four KT patients were enrolled for this PAD study. Fasting blood samples were obtained to measure serum OPG levels by using enzyme-linked immunosorbent assay kits. The ankle-brachial index (ABI) of less than 0.9 was applied for PAD diagnosis.

Results

Thirteen patients (17.6%) were diagnosed with PAD. Diabetes (P = 0.025), smoking (P = 0.010), and increased OPG levels (P = 0.001) were significantly more frequent in the PAD group. Multivariate logistic regression analysis showed that serum OPG (odds ratio [OR], 1.336; 95% CI [1.108–1.611]; P = 0.002) and diabetes (OR, 7.120; 95% CI [1.080–46.940]; P = 0.041) were independent predictors of PAD in KT patients. The area under the receiver operating characteristic (ROC) curve determined that the probability of a serum OPG level of 7.117 pg/L in predicting PAD in KT patients was 0.799 (95% CI [0.690–0.884]; P < 0.001).

Discussion

Exploration of reliable biomarkers for early identification of vascular risk is crucial for KT patients. Elevated serum OPG levels may predict PAD in KT patients with cutoff value of 7.117 pg/L.

Long-Term Progression of Coronary Artery Calcification Is Independent of Classical Risk Factors, C-Reactive Protein, and Parathyroid Hormone in Renal Transplant Patients

Aims

Compared to the general population, mortality is significantly increased in renal transplant recipients. In the general population, coronary artery calcification (CAC) and its evolution over time are associated with cardiovascular and all-cause mortality, and the study of this biomarker could provide useful information for describing the long-term progression of coronary heart disease in renal transplant recipients.

Methods

We followed up a cohort of 113 renal transplant patients by performing three multi-detector computed tomography studies over 83.6 ± 6.8 months. Data analysis was performed by logistic regression analysis and by mixed linear modelling.

Results

Progression was observed in 34.5% of patients. Baseline CAC and time-to-transplantation were the sole variables that predicted CAC evolution over time. Neither classical nor nontraditional risk factors, biomarkers of renal function (GFR) and kidney damage (albuminuria) or biomarkers of bone mineral disorder (BMD), such as serum phosphorus, calcium, and PTH, were associated with the long-term progression of coronary calcification. Serum triglycerides predicted CAC progression only in logistic regression analysis, while in addition to baseline CAC, time to transplantation was the sole variable predicting CAC progression when the data were analyzed by mixed linear modelling. These data suggested that, in addition to the background calcification burden, other unmeasured factors play major roles in promoting the evolution of coronary calcification in the transplant population.

Conclusion

CAC progression continued over the long-term follow-up of renal transplant patients. This phenomenon was unaccounted for by classical and nontraditional risk factors, as well as by biomarkers of renal dysfunction and renal damage.

Does the OPG/RANKL system contribute to the bone-vascular axis in chronic kidney disease? A systematic review

Vascular calcification (VC) is highly prevalent in patients with chronic kidney disease (CKD) and is strongly associated with cardiovascular mortality and morbidity. Accumulating evidence over the past decade has challenged the hypothesis of close interaction between bone and VC what raises the possibility of a common underlying pathophysiological mechanism. Lately, bone regulatory proteins such as: osteoprotegerin (OPG) and Receptor Activator for Nuclear Factor κB Ligand (RANKL) has attracted attention of researchers as a possible key mediators of bone-vascular calcification imbalance. The literature search was carried out using the MEDLINE/PubMed database and a combination of keywords and MeSH terms, and only papers published since January 2005 to July 2016 were selected. The search resulted in 562 potential articles. After selection according to the eligibility criteria, 107 studies fulfilled were included (102 full texts and 5 was case reports). OPG and RANKL plays essential role in the regulation of bone metabolism and may be regarded as a possible link between VC, bone and mineral metabolism in CKD patients. Further studies are required to determine the diagnostic significance of these proteins in evaluation of progression and severity of VC process in CKD patients. Finally, the efficacy and safety, especially in regard to VC, of anti-RANKL therapy in CKD patients requires well-designed prospective, randomized trials.

Cardiovascular calcifications in chronic kidney disease: Potential therapeutic implications

Cardiovascular (CV) calcification is a highly prevalent condition at all stages of chronic kidney disease (CKD) and is directly associated with increased CV and global morbidity and mortality. In the first part of this review, we have shown that CV calcifications represent an important part of the CKD-MBD complex and are a superior predictor of clinical outcomes in our patients. However, it is also necessary to demonstrate that CV calcification is a modifiable risk factor including the possibility of decreasing (or at least not aggravating) its progression with iatrogenic manoeuvres. Although, strictly speaking, only circumstantial evidence is available, it is known that certain drugs may modify the progression of CV calcifications, even though a direct causal link with improved survival has not been demonstrated. For example, non-calcium-based phosphate binders demonstrated the ability to attenuate the progression of CV calcification compared with the liberal use of calcium-based phosphate binders in several randomised clinical trials. Moreover, although only in experimental conditions, selective activators of the vitamin D receptor seem to have a wider therapeutic margin against CV calcification. Finally, calcimimetics seem to attenuate the progression of CV calcification in dialysis patients. While new therapeutic strategies are being developed (i.e. vitamin K, SNF472, etc.), we suggest that the evaluation of CV calcifications could be a diagnostic tool used by nephrologists to personalise their therapeutic decisions.

High Serum Osteoprotegerin Is Associated with Arterial Stiffness in Kidney Transplant Patients

Osteoprotegerin (OPG) is a cytokine that regulates bone resorption by inhibiting osteoclastogenesis, and OPG has been implicated in the process that causes vascular stiffness. An increase in serum OPG level has been associated with the development of arterial stiffness. Kidney transplant (KT) patients are susceptible to aortic stiffness, which is considered to be a predictor of cardiovascular events in this patient population. Carotid-femoral pulse wave velocity (cfPWV) has emerged as a gold standard for non-invasive evaluation of aortic stiffness. The aim of this study was to evaluate the relationship between serum OPG concentration and cfPWV among KT patients. Fasting blood samples were obtained from 57 KT patients and their cfPWV was measured using applanation tonometry. The serum OPG levels were measured using an enzyme-linked immunosorbent assay. Univariable linear regression analysis showed that the cfPWV in KT patients was significantly and positively correlated with age, body weight, waist circumference, body mass index, log-creatinine, systolic blood pressure, diastolic blood pressure, pulse pressure, and the log-OPG concentration. KT patients with metabolic syndrome had higher cfPWV values than those without metabolic syndrome (P = 0.036), which indicates a higher incidence of aortic stiffness in this patient population. Multivariable forward stepwise linear regression analysis of the significant variables showed that the log-OPG (P = 0.001), the log-creatinine (P = 0.004), and the SBP (P = 0.005) remained as independent and positive predictors of cfPWV values. These findings indicate that serum OPG levels are positively associated with cfPWV in KT patients.

Receptor activator of nuclear factor κB ligand/osteoprotegerin axis and vascular calcifications in patients with chronic kidney disease

Vascular calcifications are commonly observed in patients with chronic kidney disease (CKD) and contribute to the excessive cardiovascular morbidity and mortality rates observed in these patients populations. Although the pathogenetic mechanisms are not yet fully elucidated, recent evidence suggests a link between bone metabolism and the development and progression of vascular calcifications. Moreover, accumulating data indicate that receptor activator of nuclear factor κB ligand/osteoprotegerin axis which plays essential roles in the regulation of bone metabolism is also involved in extra-osseous bone formation. Further studies are required to establish the prognostic significance of the above biomarkers as predictors of the presence and severity of vascular calcifications in CKD patients and of cardiovascular morbidity and mortality. Moreover, randomized clinical trials are needed to clarify whether inhibition of osteoclast activity will protect from vascular calcifications.

Vascular calcification, bone and mineral metabolism after kidney transplantation

The development of end stage renal failure can be seen as a catastrophic health event and patients with this condition are considered at the highest risk of cardiovascular disease among any other patient groups and risk categories. Although kidney transplantation was hailed as an optimal solution to such devastating disease, many issues related to immune-suppressive drugs soon emerged and it became evident that cardiovascular disease would remain a vexing problem. Progression of chronic kidney disease is accompanied by profound alterations of mineral and bone metabolism that are believed to have an impact on the cardiovascular health of patients with advanced degrees of renal failure. Cardiovascular risk factors remain highly prevalent after kidney transplantation, some immune-suppression drugs worsen the risk profile of graft recipients and the alterations of mineral and bone metabolism seen in end stage renal failure are not completely resolved. Whether this complex situation promotes progression of vascular calcification, a hall-mark of advanced chronic kidney disease, and whether vascular calcifications contribute to the poor cardiovascular outcome of post-transplant patients is reviewed in this article.

Mineral and bone disorder after kidney transplantation

After successful kidney transplantation, accumulated waste products and electrolytes are excreted and regulatory hormones return to normal levels. Despite the improvement in mineral metabolites and mineral regulating hormones after kidney transplantation, abnormal bone and mineral metabolism continues to present in most patients. During the first 3 mo, fibroblast growth factor-23 (FGF-23) and parathyroid hormone levels decrease rapidly in association with an increase in 1,25-dihydroxyvitamin D production. Renal phosphate excretion resumes and serum calcium, if elevated before, returns toward normal levels. FGF-23 excess during the first 3-12 mo results in exaggerated renal phosphate loss and hypophosphatemia occurs in some patients. After 1 year, FGF-23 and serum phosphate return to normal levels but persistent hyperparathyroidism remains in some patients. The progression of vascular calcification also attenuates. High dose corticosteroid and persistent hyperparathyroidism are the most important factors influencing abnormal bone and mineral metabolism in long-term kidney transplant (KT) recipients. Bone loss occurs at a highest rate during the first 6-12 mo after transplantation. Measurement of bone mineral density is recommended in patients with estimated glomerular filtration rate > 30 mL/min. The use of active vitamin D with or without bisphosphonate is effective in preventing early post-transplant bone loss. Steroid withdrawal regimen is also beneficial in preservation of bone mass in long-term. Calcimimetic is an alternative therapy to parathyroidectomy in KT recipients with persistent hyperparathyroidism. If parathyroidectomy is required, subtotal to near total parathyroidectomy is recommended. Performing parathyroidectomy during the waiting period prior to transplantation is also preferred in patients with severe hyperparathyroidism associated with hypercalcemia.

Sclerostin Serum Levels and Vascular Calcification Progression in Prevalent Renal Transplant Recipients

CONTEXT

Vascular calcification (VC) is prevalent and progressive in renal transplant recipients (RTRs). Recent cross-sectional data suggest that activated Wnt signaling contributes to VC.

OBJECTIVE

The objective was to investigate whether circulating levels of the Wnt antagonist sclerostin associate with progression of VC.

DESIGN

This was a post hoc analysis of the longitudinal observational Brussels Renal Transplant Cohort study.

SETTING

The setting was a tertiary care academic hospital.

PATIENTS

Coronary artery calcification and aorta calcification were measured by multislice spiral computerized tomography in 268 prevalent RTRs (age, 53 ± 13 y; 61% male) at baseline and remeasured in 189 patients after a median follow-up of 4.4 years. Baseline serum sclerostin levels were assessed on stored blood samples. Regression analysis was performed to identify determinants of baseline VC and progression.

MAIN OUTCOME MEASURE

The main outcome measure was progression of VC.

RESULTS

VC was present in up to 84% of participants at baseline. Almost half of the patients showed progression of VC, according to Hokanson criteria. The cross-sectional analysis at baseline demonstrated a direct association between sclerostin levels and VC score in univariate analysis, which became inverse after adjustment for age, gender and PTH level. Remarkably, a lower sclerostin level was identified as an independent determinant of a higher baseline aorta calcification score in the final regression model. Moreover, baseline sclerostin levels showed an inverse association with VC progression, at least after adjustment for traditional risk factors.

CONCLUSIONS

Serum sclerostin levels inversely associated with VC burden and progression in prevalent RTRs after adjustment for traditional risk factors. Our data corroborate previous findings in nontransplanted chronic kidney disease patients and support the notion that sclerostin may be up-regulated in the vascular wall during the VC process as part of a local counterregulatory mechanism directed to suppress VC. Additional clinical and experimental data are required for confirmation.

Serum osteoprotegerin is associated with pulse pressure in kidney transplant recipients

Pulse pressure (PP) reflects increased large artery stiffness, which is caused, in part, by arterial calcification in patients with chronic kidney disease. PP has been shown to predict both cardiovascular and cerebrovascular events in various patient populations, including kidney transplant (KTX) recipients. Osteoprotegerin (OPG) is a marker and regulator of arterial calcification, and it is related to cardiovascular survival in hemodialysis patients. Here we tested the hypothesis that OPG is associated with increased pulse pressure. We cross-sectionally analyzed the association between serum OPG and PP in a prevalent cohort of 969 KTX patients (mean age: 51 +/- --13 years, 57% male, 21% diabetics, mean eGFR 51 +/- 20 ml/min/1.73 m2). Independent associations were tested in a linear regression model adjusted for multiple covariables. PP was positively correlated with serum OPG (rho = 0.284, p < 0.001). Additionally, a positive correlation was seen between PP versus age (r = 0.358, p < 0.001), the Charlson Comorbidity Index (r = 0.232, p < 0.001), serum glucose (r = 0.172, p < 0.001), BMI (r = 0.133, p = 0.001) and serum cholesterol (r = 0.094, p = 0.003). PP was negatively correlated with serum Ca, albumin and eGFR. The association between PP and OPG remained significant after adjusting for multiple potentially relevant covariables (beta = 0.143, p < 0.001). We conclude that serum OPG is independently associated with pulse pressure in kidney transplant recipients.

Markers of bone remodeling are associated with arterial stiffness in renal transplanted subjects

BACKGROUND

Bone-vessel interaction in chronic renal failure remains poorly understood and could be driven by bone remodeling factors including osteoprotegerin (OPG), fibroblast growth factor 23 (FGF23), parathormone and vitamin D. Only few data are available in renal transplantation. The aim of this study was to investigate the relationship between bone remodeling factors and large artery function in renal transplant patients.

METHODS

89 renal transplant patients were enrolled in this cross-sectional study. Carotid to femoral pulse wave velocity (PWV) and central augmentation index (AIx) were determined as an estimation of large artery function. Blood samples were collected for measurement of vascular risk markers. Independent predictors were identified by multivariate linear regression through backward feature selection using Akaike's information criteria.

RESULTS

At multivariate analysis, age (p < 0.001) and systolic arterial pressure (p = 0.003) were significantly associated with PWV but not AIx. In addition, both elevated blood concentrations of 1.25(OH)2 vitamin D (p = 0.013) and OPG (p = 0.047) were still significantly related to high PWV.

CONCLUSIONS

These results underline that age and mean arterial pressure are the main determinants of PWV following renal transplantation. Among bone remodeling biomarkers, plasma OPG and active vitamin D were the strongest determinants of arterial stiffness.

Are there ways to attenuate arterial calcification and improve cardiovascular outcomes in chronic kidney disease?

The risk of cardiovascular mortality among patients with end-stage renal disease is several times higher than general population. Arterial calcification, a marker of atherosclerosis and a predictor of cardiovascular mortality, is common in chronic kidney disease (CKD). The presence of traditional cardiovascular risk factors such as diabetes, hypertension, hyperlipidemia, and advanced age cannot fully explain the high prevalence of atherosclerosis and arterial calcification. Other factors specific to CKD such as hyperphosphatemia, excess of calcium, high dose active vitamin D and prolonged dialysis vintage play important roles in the development of arterial calcification. Due to the significant health risk, it is prudent to attempt to lower arterial calcification burden in CKD. Treatment of hyperlipidemia with statin has failed to lower atherosclerotic and arterial calcification burden. Data on diabetes and blood pressure controls as well as smoking cessation on cardiovascular outcomes in CKD population are limited. Currently available treatment options include non-calcium containing phosphate binders, low dose active vitamin D, calcimimetic agent and perhaps bisphosphonates, vitamin K and sodium thiosulfate. Preliminary data on bisphosphonates, vitamin K and sodium thiosulfate are encouraging but larger studies on efficacy and outcomes are needed.

Regression of vascular calcification in chronic kidney disease - feasible or fantasy? a review of the clinical evidence

The complex relationships between cardiovascular, renal, and bone disease are increasingly recognized but not yet clearly understood. Vascular calcification (VC) represents a common end point between these interlinked systems. It is highly prevalent in chronic kidney disease (CKD) and may be responsible for some of the excess cardiovascular events seen in this condition. There is much interest in developing therapeutic agents to stop its development or reverse its progression. Traditionally considered to be due to abnormalities in calcium and phosphate metabolism alone, VC is now known to be the product of active, dynamic processes within the vessel wall. Primary prevention of VC is possible through successful prevention or reversal of progressive renal dysfunction, hypertension and hyperlipidaemia, but is challenging given the increasing global prevalence of these risk factors. Secondary prevention of VC through tight control of calcium and phosphate, can be achieved by dietary or pharmacological means. Both the modification of haemodialysis duration or methods and the use of renal transplantation have an effect. Novel drugs such as cinacalcet were hoped to halt calcification but results have been mixed, and no intervention has yet been shown to reverse calcification reliably. A new range of experimental targets involved in the putative mediatory pathways between bone and vascular disease has emerged. Aiming to manipulate the active mechanisms involved in calcium deposition, these hold hope for reversal of calcification, but are still theoretical or in early animal or human experimentation.

Osteoprotegerin and kidney disease

Vascular calcification in chronic kidney disease (CKD) patients is associated to increased mortality. Osteoprotegerin (OPG) is a soluble tumor necrosis factor (TNF) superfamily receptor that inhibits the actions of the cytokines receptor activator of nuclear factor kappa-B ligand (RANKL) and TNF-related apoptosis-inducing ligand (TRAIL) by preventing their binding to signaling receptors in the cell membrane. OPG-deficient mice display vascular calcification while OPG prevented calcification of cultured vascular smooth muscle cells and protected kidney cells from TRAIL-induced death. OPG may be a biomarker in patients with kidney disease. Circulating OPG is increased in predialysis, dialysis and transplant CKD patients and may predict vascular calcification progression and patient survival. By contrast, circulating OPG is decreased in nephrotic syndrome. In addition, free and exosome-bound urinary OPG is increased in human kidney disease. Increased urinary OPG has been associated with lupus nephritis activity. Despite the association of high OPG levels with disease, experimental functional information available suggests that OPG might be protective in kidney disease and in vascular injury in the context of uremia. Thus, tissue injury results in increased OPG, while OPG may protect from tissue injury. Recombinant OPG was safe in phase I randomized controlled trials. Further research is needed to fully define the therapeutic and biomarker potential of OPG in patients with kidney disease.

Vascular calcification in long-term kidney transplantation

AIM

Vascular calcification (VC) is common among patients with chronic kidney disease (CKD) due to the strong prevalence of cardiovascular and CKD-related risk factors such as diabetes mellitus (DM), hypertension and phosphate retention. Kidney transplantation improves kidney function and abnormal mineral metabolism at the same time. It remains unclear whether kidney transplantation favourably impacts VC in the long-term.

METHODS

The present study examined VC in 132 kidney transplant (KT) recipients who had been transplanted for longer than one year. The severity of VC was compared to 129 CKD stages 5-5D patients on a kidney transplant (KT) waiting list.

RESULTS

The median KT vintage was 88 months. The prevalence of VC among KT and CKD patients were 54.5% and 62.8%, respectively, (P = 0.2). There were no differences in age, gender, body mass index (BMI), the prevalence of DM or CVD between the two groups. Among patients with calcification, a more severe degree was observed in KT recipients (P = 0.01). Aging, DM, CVD and dialysis vintage were associated with significant VC in both groups. The degree of VC in KT recipients was more pronounced than that in CKD patients among those who experienced prolonged dialysis vintage (>2 years) (P = 0.04). Among KT recipients, the severity of VC increased with the length of time after transplantation and became more substantial after 5 years.

CONCLUSIONS

Long-term KT recipients demonstrated a more severe degree of VC compared to matched CKD stages 5-5D patients. The severity of VC became more pronounced among those with longer transplant vintage and was in part influenced by past dialysis experience.

Elevated osteoprotegerin predicts declining renal function in elderly women: a 10-year prospective cohort study

BACKGROUND

Elevated osteoprotegerin (OPG) levels are inversely correlated with creatinine clearance and end-stage renal disease in patients with diabetes, however its role in predicting decline in renal function and progression to a more advanced stage disease in the elderly general population is unknown.

METHODS

This was a prospective cohort study of 1,157 elderly women with serum OPG measured in 1998 and renal function estimated using serum creatinine and cystatin C-based estimated glomerular filtration rate (eGFR) at 5-yearly intervals. The primary objective of the study was to determine the relationship of circulating OPG levels with 5- and 10-year renal decline.

RESULTS

At baseline, participants with elevated OPG above the median (≥2.2 ng/ml) had a 5.0% lower CKD-EPI-creatinine and cystatin C eGFR compared to participants with lower OPG levels. In multivariable-adjusted linear regression models, elevated OPG levels at baseline were associated with greater 5- and 10-year decline in CKD-EPI-creatinine and cystatin C eGFR (-0.105, p = 0.002 and -0.104, p = 0.010, respectively). Elevated OPG at baseline was associated with increased 5- and 10-year risk of rapid renal decline (OR 2.13, 95% CI 1.33-3.43, p = 0.002 and OR 4.10, 95% CI 1.49-11.27, p = 0.006, respectively) and renal disease hospitalizations or deaths (HR 1.99, 95% CI 1.31-3.03, p = 0.001) after adjusting for known risk factors.

CONCLUSION

Elevated OPG levels are associated with long-term renal dysfunction and may be provide a useful biomarker to predict the trajectory of renal decline in older women.

Calcium and osteoprotegerin levels predict the progression of the abdominal aortic calcifications after kidney transplantation

Background

Vascular calcifications (VCs) are a cardiovascular risk factor in patients affected by chronic kidney disease and after kidney transplantation (KTx). We evaluated the prevalence of VCs at the abdominal aortic site in KTx patients at the time of transplantation and 1 year after KTx, exploring the possibly associated factors.

Methods

In 107 transplanted patients, the following parameters were evaluated at the first and twelfth month after KTx: the aortic calcification index (ACI), fibroblast growth factor 23, osteoprotegerin (OPG), fetuin A, and clinical and biochemical parameters. Patients were followed up for 2 years after KTx.

Results

At the time of KTx, 60% of patients had some degree of VC (ACI>0), whereas 40% had no VC. One year after KTx, VCs worsened in 26% of patients, whereas in 74%, VCs remained stable or improved. The progression of VC was observed almost exclusively in patients with a positive ACI score at the first month. At the multivariate analysis, serum calcium, OPG, and estimated glomerular filtration rate were the only variables independently associated with the progression of VC.

Conclusions

VCs at the aortic site are frequent in KTx patients, and in a significant percentage of them, they tend to progress even in the short time. High levels of serum calcium and OPG are significantly associated with the progression of VCs. Whether these associations are based on a cause-effect relationship and their correction might impact on the calcification process could be ascertained by prospective interventional studies.

Lowering vascular calcification burden in chronic kidney disease: Is it possible?

High prevalence of atherosclerosis and arterial calcification in chronic kidney disease is far beyond the explanation by common cardiovascular risk factors such as aging diabetes, hypertension and dyslipidemia. The magnitude of coronary artery calcification is independently and inversely associated with renal function. In addition to cardiovascular risk factors, other chronic kidney disease-related risks such as phosphate retention, excess of calcium and prolonged dialysis vintage also contribute to the development of vascular calcification. Strategies to lower vascular calcification burden in chronic kidney disease population should include minimizing chronic kidney disease and atherosclerotic risk factors. Current therapies available are non-calcium containing phosphate binders, low dose active vitamin D and calcimimetic agent. The role of bisphosphonates in vascular calcification in chronic kidney disease population remains unclear. Preliminary data on sodium thiosulfate are promising, however, larger studies on efficacy and patient outcomes are necessary. Several large randomized controlled trials have confirmed the lack of benefit of statin in attenuating the progression of vascular calcification.

Progression of coronary artery calcification after kidney transplantation

Calcification of coronary vessels progresses rapidly in hemodialysis (HD) patients and comprises a strong predictor of cardiovascular events. The aim of this prospective study was to evaluate the coronary artery calcification (CAC) in patients with end stage renal disease undergoing regular HD and to determine the effect of renal transplantation (RT) in the progression of CAC, using the Agatston technique for calcium scoring. The study included 20 patients with end-stage renal disease undergoing a regular HD treatment (16 males, 4 females) 54.1 ± 9.5 years old who had just received a renal transplant and 16 more HD patients (11 males, 5 females) 54.4 ± 13.8 years old as control group. The baseline evaluation showed a very high prevalence of CAC in both groups, which was positively correlated with age (p < 0.001) and CRP (p = 0.03). The second (follow-up) evaluation showed a significant slower progression of calcification after RT. In both groups, high calcium score values in the follow-up evaluation had a strong positive correlation with baseline calcium score (p < 0.001).

Advanced abdominal arterial calcification sparing kidney allograft--case report

Excess and progressing arterial calcification is a frequent finding in patients with chronic kidney disease and in diabetics. Vascular calcification present in patients on dialysis, usually continues to progress (although possibly with slower rate) in patients after kidney transplantation. These observations are limited mostly to aorta and coronary arteries; virtually no data exist on progression in vascular calcification within the vasculature of transplanted kidney. The case report presents the patient with diabetes and non-functioning renal transplant back on dialysis with extremely severe intra-abdominal artery calcification, sparing renal artery of transplanted kidney. Calcification did not develop within transplanted kidney despite 10 years of exposition to diabetic environment and a few years of chronic kidney disease after transplantation, including CKD-T stage 5 for at least one year after re-starting of dialysis. To the best of our knowledge, this is the second report ever describing sparing of kidney graft from calcification despite disseminated calcification in other vascular beds. It is tempting to speculate that some "intrinsic" factors exist within the transplanted kidney that protects it from calcification despite exposure to procalcifying milieu of diabetes and uremia.

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.

Osteoprotegerin as a predictor of renal and cardiovascular outcomes in renal transplant recipients: follow-up data from the ALERT study

BACKGROUND

In patients with chronic kidney disease, vascular calcification contributes to increased cardiovascular (CV) morbidity and mortality. CV risk remains high after successful renal transplantation. Osteoprotegerin (OPG) is a glycoprotein, involved in the regulation of the vascular calcification process. Previous studies have shown that elevated OPG is predictive of mortality in high-risk populations. The aim of this study was to investigate the prognostic value of OPG for graft function, CV events and all-cause death, in a large transplant cohort.

METHODS

OPG was measured at baseline in renal transplant recipients enrolled in the Assessment of Lescol in Renal Transplantation (ALERT) study, a randomized placebo-controlled intervention study comparing fluvastatin and placebo. Patients were followed for 6.7 years with evaluation of pre-specified end points, graft loss, graft function, CV events and death.

RESULTS

OPG was analysed in 1889 renal transplant recipients, with a mean value of 4.69 ± 1.85 pg/L. The number of renal and CV events increased by quartiles of OPG. In the multivariate analysis, OPG in the fourth as compared to first quartile was an independent predictor of graft failure or doubling of serum creatinine [hazard ratio (HR) 2.20 (1.56-3.11), P < 0.001], major CV events [HR 2.40 (1.58-3.64), P < 0.001], cardiac mortality [HR 2.80 (1.32-5.94), P = 0.007] and all-cause mortality [HR 2.31 (1.53-3.49), P < 0.001].

CONCLUSION

In a large cohort of kidney transplant patients with long-term follow-up, OPG was independently associated with renal events, CV events and mortality.

Progression of coronary artery calcification in renal transplant recipients

BACKGROUND

Cardiovascular disease is the leading cause of mortality among renal transplant recipients. In the general population, coronary artery calcification (CAC) and progression of CAC are predictors of future cardiac risk. We conducted a study to determine the progression of CAC in renal transplant recipients; we also examined the factors associated with progression and the impact of the analytic methods used to determine CAC progression.

METHODS

We used multi-detector computed tomography to examine CAC in 150 prevalent renal transplant recipients, who did not have a documented cardiovascular disease. A baseline and a follow-up scan were performed and changes in CAC scores were evaluated in each patient individually, to calculate the incidence of CAC progression. Multivariate logistic regression analysis was used to evaluate the determinants of CAC progression.

RESULTS

Baseline CAC prevalence was 35.3% and the mean CAC score was 60.0 ± 174.8. At follow-up scan that was performed after an average of 2.8 ± 0.4 years, CAC prevalence increased to 64.6% and the mean CAC score to 94.9 ± 245.7. Progression of individual CAC score was found between 28.0 and 38.0%, depending on the method used to define progression. In patients with baseline CAC, median annualized rate of CAC progression was 11.1. Baseline CAC, high triglyceride and bisphosphonate use were the independent determinants of CAC progression.

CONCLUSIONS

Renal transplantation does not stop or reverse CAC. Progression of CAC is the usual evolution pattern of CAC in renal transplant recipients. Beside baseline CAC, high triglyceride level and bisphosphonate use were associated with progression of CAC.

Coronary artery calcification and coronary ischaemia in renal transplant recipients

BACKGROUND

Cardiovascular disease is the leading cause of mortality among renal transplant recipients. Data on the relationship between coronary artery calcification (CAC) and coronary ischaemia in renal transplantation patients are scant. We conducted a study to determine the prevalence and determinants of CAC in these patients; we also examined the frequency of coronary ischaemia in patients with moderate and severe CAC.

METHODS

We used multi-detector spiral computed tomography to examine CAC in 178 consecutive renal transplant recipients. Angina pectoris was sought with the Rose questionnaire. The extent of calcification was measured by Agatston score. Myocardial perfusion scintigraphy was performed in patients with moderate and severe CAC. Multivariate logistic and linear regression analysis was used to evaluate the determinants of CAC presence and CAC score, respectively.

RESULTS

CAC was present in 72 patients (40.4%), mean CAC score was 113.7±275.5 (median: 0 and range: 0-1712). Age, time on transplantation and Rose angina pectoris were the independent determinants of both CAC presence and high CAC scores in all multivariate models. Coronary ischaemia was detected in 17.1% of the patients with moderate-to-severe CAC.

CONCLUSIONS

CAC is highly prevalent in renal transplant recipients; it is associated with symptoms of coronary ischaemia. Time on transplantation is an independent determinant of CAC. Future studies to evaluate the prognostic significance of CAC in these patients are necessary.