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1.  Quantification of Lower Leg Arterial Calcifications by High-Resolution Peripheral Quantitative Computed Tomography 
Bone  2013;58:42-47.
Vascular calcifications and bone health seem to be etiologically linked via common risk factors such as aging and subclinical chronic inflammation. Epidemiologic studies have shown significant associations between low bone mineral density (BMD), fragility fractures and calcifications of the coronary arteries and the abdominal aorta. In the last decade, high-resolution peripheral quantitative computed tomography (HR-pQCT) has emerged as in-vivo research tool for the assessment of peripheral bone geometry, density, and microarchitecture. Although vascular calcifications are frequently observed as incidental findings in HR-pQCT scans, they have not yet been incorporated into quantitative HR-pQCT analyses. We developed a semi-automated algorithm to quantify lower leg arterial calcifications (LLAC), captured by HR-pQCT. The objective of our study was to determine validity and reliability of the LLAC measure.
HR-pQCT scans were downscaled to a voxel size of 250 µm. After subtraction of bone volumes from the scans, LLAC were detected and contoured by a semi-automated, dual-threshold seed-point segmentation. LLAC mass (in mg hydroxyapatite; HA) was calculated as the product of voxel-based calcification volume (mm3) and mean calcification density (mgHA/cm3)/1000. To determine validity, we compared LLAC to coronary artery calcifications (CAC), as quantified by multi-detector computed tomography (MDCT) and Agatston scoring in forty-six patients on chronic hemodialysis. Moreover, we investigated associations of LLAC with age, time on dialysis, type-2 diabetes mellitus, history of stroke, and myocardial infarction. In a second step, we determined intra- and inter-reader reliability of the LLAC measure.
In the validity study, LLAC were present (>0 mgHA) in 76% of patients, 78% of patients had CAC (>0 mgHA). Median LLAC was 6.65 (0.08 – 24.40) mgHA and median CAC as expressed by Agatston score was 266.3 (15.88 – 1877.28). We found a significant positive correlation between LLAC and CAC (rho=0.6; p<0.01). Dialysis patients with type-2 diabetes mellitus (DM; 35%) and history of stroke (13%) had higher median LLAC than patients without those conditions (DM 20.0 fold greater, p=0.006; Stroke 5.1 fold greater, p=0.047;). LLAC was positively correlated with time on dialysis (rho=0.337, p=0.029), there was a trend towards a positive association of LLAC and age (rho=0.289, p=0.053). The reliability study yielded excellent intra- and inter-reader agreement of the LLAC measure (intra-reader ICC=0.999, 95% CI=0.998–1.000; inter-reader ICC=0.998, 95% CI=0.994–0.999).
Our study indicates that the LLAC measure has good validity and excellent reliability. The use of HR-pQCT for the simultaneous evaluation of arterial calcifications, peripheral bone geometry, bone density, and bone microarchitecture should facilitate future research on osteo-vascular interactions and potential associations with cardiovascular events.
PMCID: PMC4042679  PMID: 23954758
HR-pQCT; Lower Leg Arterial Calcifications; Quantification; Agatston-Score
2.  Risk factors of one year increment of coronary calcifications and survival in hemodialysis patients 
BMC Nephrology  2010;11:10.
Heart and coronary calcifications in hemodialysis patients are of very common occurrence and linked to cardiovascular events and mortality. Several studies have been published with similar results. Most of them were mainly cross-sectional and some of the prospective protocols were aimed to evaluate the results of the control of altered biochemical parameters of mineral disturbances with special regard to serum calcium, phosphate and CaxP with the use of calcium containing and calcium free phosphate chelating agents. The aim of the present study was to evaluate in hemodialysis patients classic and some non classic risk factors as predictors of calcification changes after one year and to evaluate the impact of progression on survival.
81 patients on hemodialysis were studied, with a wide age range and HD vintage. Several classic parameters and some less classic risk factors were studied like fetuin-A, CRP, 25-OHD and leptin. Calcifications, as Agatston scores, were evaluated with Multislice CT basally and after 12-18 months.
Coronary artery calcifications were observed in 71 of 81 patients. Non parametric correlations between Agatston scores and Age, HD Age, PTH and CRP were significant. Delta increments of Agatston scores correlated also with serum calcium, CaxP, Fetuin-A, triglycerides and serum albumin. Logistic regression analysis showed Age, PTH and serum calcium as important predictors of Delta Agatston scores. LN transformation of the not normally distributed variables restricted the significant correlations to Age, BMI and CRP. Considering the Delta Agatston scores as dependent, significant predictors were Age, PTH and HDL. A strong association was found between basal calcification scores and Delta increment at one year. By logistic analysis, the one year increments in Agatston scores were found to be predictors of mortality. Diabetic and hypertensive patients have significantly higher Delta scores.
Progression of calcification is of common occurrence, with special regard to elevated basal scores, and is predictive of survival. Higher predictive value of survival is linked to the one year increment of calcification scores. Some classic and non classic risk factors play an important role in progression. Some of them could be controlled with appropriate management with possible improvement of mortality.
PMCID: PMC2903573  PMID: 20565936
3.  Regression of vascular calcification following an acute episode of calciphylaxis: a case report 
In clinical situations, vascular calcification tends to progress and is difficult to completely arrest or reverse. Calciphylaxis, a severe complication of end-stage renal disease, is a specific form of vascular calcification. Control studies have provided evidence that monotherapy with sodium thiosulfate or cinacalcet delays the progression of vascular calcification. Successful treatment of calciphylaxis with sodium thiosulfate or cinacalcet has also been reported. We report a case demonstrating the regression of vascular calcification following an acute episode of necrotic skin lesions suspected to be calciphylaxis. During the successful multimodal treatment, sodium thiosulfate and cinacalcet were sequentially administered in addition to surgical debridement and percutaneous transluminal angioplasty.
Case presentation
We describe the case of a 71-year-old Asian woman on hemodialysis who presented with suspected calciphylaxis lesions in her lower left leg. Plain radiographs revealed diffuse calcified vessel changes in her lower extremities. During the initial wound treatment with a course of intravenous sodium thiosulfate, our patient’s predialysis serum levels of total calcium markedly increased, yielding no calciphylaxis improvement. The necrotic wounds began healing only after surgical debridement. A percutaneous transluminal angioplasty was performed to dilate a 70% stenosis in her left posterior tibial artery. Our patient was then treated with cinacalcet, resulting in improved control of her calcium, phosphate and parathyroid hormone serum levels. The lesions completely healed after six months of multimodal treatment. Repeated plain radiographs in the following two years revealed gradual vascular calcification regression in her lower extremities.
In addition to the favorable outcome of our patient’s wounds, radiology was used to document the regression of calcification in the large and small arteries of her lower limbs. However, it is difficult to determine the precise mechanism of the multimodal treatment that caused the vascular calcification regression and wound healing. The clinical course suggested that the surgical treatment and percutaneous transluminal angioplasty substantially contributed to healing her wounds. Cinacalcet and sodium thiosulfate may have played distinct roles in the regression of her vascular calcification. A well-controlled study or large case series are required to assess the additive effects of these agents when treating vascular calcification.
PMCID: PMC3930056  PMID: 24524553
Calciphylaxis; Cinacalcet; Sodium thiosulfate; Vascular calcification
4.  Phosphate binders: Sevelamer in the prevention and treatment of hyperphosphataemia in chronic renal failure 
Hippokratia  2011;15(Suppl 1):22-26.
In chronic kidney disease patients, bone and mineral abnormalities have a major impact on morbidity and mortality. Hyperphosphatemia has been associated with increased mortality and with the development of cardiovascular calcification, an independent predictor of mortality. Sevelamer, or more precisely 'sevelamer hydrochloride', is a weakly basic anion-exchange resin in the chloride form that was introduced in 1997 for the treatment of the hyperphosphataemia of patients with end-stage renal failure. Sevelamer sequesters phosphate within the gastrointestinal tract, so prevents its absorption and enhances its faecal excretion. Over the succeeding years, large numbers of patients have been treated with sevelamer, and it has fulfilled expectations in helping to control the hyperphosphataemia of end-stage renal failure. Additionally treatment with sevelamer was accompanied with lower incidence of hypercalcemia, decreased incidence of low PTH levels, a 15-31% decrease of LDL-cholesterol both in dialysis and predialysis patients, decreased C-reactive protein, amelioration of hyperuricemia and low fetuin A, decrease of uremic toxins, suggesting an overall anti-inflammatory effect. In incident dialysis patients, treatment with sevelamer has been associated with better survival, while in prevalent patients a clear benefit could only be demonstrated in older patients and in patients treated for more than 2 years. In dialysis patients, the treatment of hyperphospathemia with calcium based compounds, when compared with sevelamer, is associated with more frequent episodes of hypercalcemia, suppression of intact PTH and with progression of coronary calcifications. In the presence of adynamic bone disease, calcium load has a significantly higher impact on aortic calcifications and stiffening. Sevelamer treatment resulted in no statistically significant changes in bone turnover or mineralization compared with calcium carbonate, but bone formation rate increased and trabecular architecture improved only with sevelamer. In conclusion, the treatment of hyperphosphatemia with sevelamer hydrochloride, a noncalcium and non-metal containing phosphate binder, is associated with a beneficial effect on vascular calcification progression, bone disease and most likely with a survival benefit in some hemodialysis patients populations. Sevelamer carbonate is an improved, buffered form of sevelamer hydrochloride developed for the treatment of hyperphosphataemia in CKD patients. Sevelamer carbonate formulated as a powder for oral suspension presents a novel, patient- friendly alternative to tablet phosphate binders. Safety and efficacy of sevelamer carbonate powder compared with sevelamer hydrochloride tablets in CKD patients are equivalent, with Sevelamer carbonate having fewer side effects from gastrointestinal tract.
PMCID: PMC3139674  PMID: 21897754
sevelamer hydrochloride; sevelamer carbonate; hyperphosphatemia; vascular calcification
5.  Long-term effect of cinacalcet hydrochloride on abdominal aortic calcification in patients on hemodialysis with secondary hyperparathyroidism 
Secondary hyperparathyroidism (SHPT) is one of the common complications in dialysis patients, and is associated with increased risk of vascular calcification. The effects of cinacalcet hydrochloride treatment on bone and mineral metabolism have been previously reported, but the benefit of cinacalcet on vascular calcification remains uncertain. The aim of this study was to evaluate the impact of cinacalcet on abdominal aortic calcification in dialysis patients.
Subjects and methods
Patients were on maintenance hemodialysis with insufficiently controlled SHPT (intact parathyroid hormone [PTH] >180 pg/mL) by conventional therapies. All subjects were initially administered 25 mg cinacalcet daily, with concomitant use of calcitriol analogs. Abdominal aortic calcification was annually evaluated by calculating aortic calcification area index (ACAI) using multidetector computed tomography (MDCT), from 12 months before to 36 months after the initiation of cinacalcet therapy.
Twenty-three patients were analyzed in this study. The mean age was 59.0±8.7 years, 34.8% were women, and the mean dialysis duration was 163.0±76.0 months. After administration of cinacalcet, serum levels of intact PTH, phosphorus, and calcium significantly decreased, and mean Ca × P values significantly decreased from 67.4±7.9 mg2/dL2 to 52±7.7 mg2/dL2. Although the ACAI value did not decrease during the observation period, the increase in ACAI between 24 months and 36 months after cinacalcet administration was significantly suppressed.
Long-term administration of cinacalcet was associated with reduced progression of abdominal aortic calcification, and achieving appropriate calcium and phosphorus levels may reduce the rates of cardiovascular events and mortality in patients on hemodialysis.
PMCID: PMC3872220  PMID: 24379691
abdominal aortic calcification; cinacalcet hydrochloride; hemodialysis
6.  Progressive coronary calcification despite intensive lipid‐lowering treatment: a randomised controlled trial 
Heart  2006;92(9):1207-1212.
To evaluate the effect of intensive lipid‐lowering treatment on coronary artery calcification in a substudy of a trial recruiting patients with calcific aortic stenosis.
In a double blind randomised controlled trial, 102 patients with calcific aortic stenosis and coronary artery calcification were randomly assigned by the minimisation technique to atorvastatin 80 mg daily or matched placebo. Coronary artery calcification was assessed annually by helical computed tomography.
48 patients were randomly assigned to atorvastatin and 54 to placebo with a median follow up of 24 months (interquartile range 24–30). Baseline characteristics and coronary artery calcium scores were similar in both groups. Atorvastatin reduced serum low density lipoprotein cholesterol (−53%, p < 0.001) and C reactive protein (−49%, p < 0.001) concentrations whereas there was no change with placebo (−7% and 17%, p > 0.95 for both). The rate of change in coronary artery calcification was 26%/year (0.234 (SE 0.037) log arbitrary units (AU)/year; n  =  39) in the atorvastatin group and 18%/year (0.167 (SE 0.034) log AU/year; n  =  49) in the placebo group, with a geometric mean difference of 7%/year (95% confidence interval −3% to 18%, p  =  0.18). Serum low density lipoprotein concentrations were not correlated with the rate of progression of coronary calcification (r  =  0.05, p  =  0.62).
In contrast to previous observational studies, this randomised controlled trial has shown that, despite reducing systemic inflammation and halving serum low density lipoprotein cholesterol concentrations, statin treatment does not have a major effect on the rate of progression of coronary artery calcification.
PMCID: PMC1861190  PMID: 16449511
7.  Inhibiting the progression of arterial calcification with vitamin K in HemoDialysis patients (iPACK-HD) trial: rationale and study design for a randomized trial of vitamin K in patients with end stage kidney disease 
Cardiovascular disease, which is due in part to progressive vascular calcification, is the leading cause of death among patients with end stage kidney disease (ESKD) on dialysis. A role for vitamin K in the prevention of vascular calcification is plausible based on the presence of vitamin K dependent proteins in vascular tissue, including matrix gla protein (MGP). Evidence from animal models and observational studies support a role for vitamin K in the prevention of vascular calcification. A large-scale study is needed to investigate the effect of vitamin K supplementation on the progression of vascular calcification in patients with ESKD, a group at risk for sub-clinical vitamin K deficiency.
We plan a prospective, randomized, double-blind, multicenter controlled trial of incident ESKD patients on hemodialysis in centers within North America. Eligible subjects with a baseline coronary artery calcium score of greater than or equal to 30 Agatston Units, will be randomly assigned to either the treatment group (10 mg of phylloquinone three times per week) or to the control group (placebo administration three times per week). The primary endpoint is the progression of coronary artery calcification defined as a greater than 15% increase in CAC score over baseline after 12 months.
Vitamin K supplementation is a simple, safe and cost-effective nutritional strategy that can easily be integrated into patient care. If vitamin K reduces the progression of coronary artery calcification it may lead to decreased morbidity and mortality in men and women with ESKD.
Trial registration
NCT 01528800.
PMCID: PMC4465015  PMID: 26075081
Vitamin K; End stage kidney disease; Hemodialysis; Coronary artery calcification; Randomized controlled trial
8.  Vascular calcification in chronic kidney disease: Pathogenesis and clinical implication 
World Journal of Nephrology  2012;1(2):43-53.
Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Vascular calcification (VC) is one of the independent risk factors associated with cardiovascular disease and cardiovascular mortality in both the general population and CKD patients. Earlier evidence revealed substantially higher prevalence of VC in young adults on chronic hemodialysis compared to the general population in the same age range, indicating the influence of CKD-related risk factors on the development of VC. Pathogenesis of VC involves an active, highly organized cellular transformation of vascular smooth muscle cells to bone forming cells evidenced by the presence of bone matrix proteins in the calcified arterial wall. VC occurs in both the intima and the media of arterial wall with medial calcification being more prevalent in CKD. In addition to traditional cardiovascular risks, risk factors specific to CKD such as phosphate retention, excess of calcium, history of dialysis, active vitamin D therapy in high doses and deficiency of calcification inhibitors play important roles in promoting the development of VC. Non-contrast multi-slice computed tomography has often been used to detect coronary artery calcification. Simple plain radiographs of the lateral lumbar spine and pelvis can also detect VC in the abdominal aorta and femoral and iliac arteries. Currently, there is no specific therapy to reverse VC. Reduction of calcium load, lowering phosphate retention using non-calcium containing phosphate binders, and moderate doses of active vitamin D may attenuate progression. Parenteral sodium thiosulfate has also been shown to delay VC progression.
PMCID: PMC3782198  PMID: 24175241
Coronary calcification; Cardiovascular; Vascular smooth muscle cells; Osteoblast; Bone; Phosphate; Vitamin D
9.  Vascular calcifications, vertebral fractures and mortality in haemodialysis patients 
Background. Vascular calcifications and the bone fractures caused by abnormal bone fragility, also called osteoporotic fractures, are frequent complications associated with chronic kidney diseases (CKD). The aim of this study was to investigate the association between vascular calcifications, osteoporotic bone fractures and survival in haemodialysis (HD) patients.
Methods. A total of 193 HD patients were followed up to 2 years. Vascular calcifications and osteoporotic vertebral fractures (quoted just as vertebral fractures in the text) were assessed by thoracic, lumbar spine, pelvic and hand X-rays and graded according to their severity. Clinical, biochemical and therapeutic data gathered during the total time spent on HD were collected.
Results. The prevalence of aortic calcifications was higher in HD patients than in a random-based general population (79% versus 37.5%, P < 0.001). Total time on any renal replacement therapy (RRT) and diabetes were positively associated with a higher prevalence of vascular calcifications. In addition to these factors, time on HD was also positively associated with the severity of vascular calcifications, and higher haemoglobin levels were associated with a lower prevalence of severe vascular calcifications in large and medium calibre arteries. The prevalence of vertebral fractures in HD patients was similar to that of the general population (26.5% versus 24.1%). Age and time on HD showed a positive and statistically significant association with the prevalence of vertebral fractures. Vascular calcifications in the medium calibre arteries were associated with a higher rate of prevalent vertebral fractures. In women, severe vascular calcifications and vertebral fractures were positively associated with mortality [RR = 3.2 (1.0–10.0) and RR = 4.8 (1.7–13.4), respectively].
Conclusions. Positive associations between vascular calcifications, vertebral fractures and mortality have been found in patients on HD.
PMCID: PMC2639312  PMID: 18725376
haemodialysis; mortality; osteoporotic fractures; vascular calcifications; vertebral fractures
10.  Progression of coronary calcification in healthy postmenopausal women 
Coronary artery calcium score incrementally improves coronary risk prediction beyond that provided by conventional risk factors. Limited information is available regarding rates of progression of coronary calcification in women, particularly those with baseline scores above zero. Further, determinants of progression of coronary artery calcification in women are not well understood. This study prospectively evaluated rates and determinants of progression of coronary artery calcium score in a group of healthy postmenopausal women.
We determined coronary calcium score by computed tomography and recorded demographic, lifestyle and health characteristics of 914 postmenopausal women, a subset of those enrolled in the Women's Health Initiative Observational Study. The 305 women with calcium score ≥10 Agatston units at baseline were invited for repeat scan. This analysis includes the 94 women who underwent second scans.
Mean age of study participants was 65 ± 9 years (mean ± SD), body mass index was 26.1 ± 6.1 kg/m2, and baseline calcium score was 162 ± 220 Agatston units. Mean interval between scans was 3.3 ± 0.7 years. A wide range of changes in coronary calcium score was observed, from -53 to +452 Agatston units/year. Women with lower scores at baseline had smaller annual increases in absolute calcium score. Coronary calcium scores increased 11, 31 and 79 Agatston units/year among women with baseline calcium score in the lowest, middle and highest tertiles. In multivariate analysis, age was not an independent predictor of absolute change in coronary calcium score. Hydroxymethylglutaryl coenzyme A reductase inhibitor (statin) use at baseline was a negative predictor (p = 0.015), whereas baseline calcium score was a strong, positive predictor (p < 0.0001) of progression of coronary calcification.
Among postmenopausal women with coronary calcium score ≥ 10 Agatston units, rates of change of coronary calcium score varied widely. In multivariate analysis, statin use was a negative independent determinant, whereas baseline calcium score was a strong positive predictor of annual change in coronary calcium score.
PMCID: PMC535923  PMID: 15574196
11.  FGF-23 associated with the progression of coronary artery calcification in hemodialysis patients 
BMC Nephrology  2013;14:241.
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.
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).
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.
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.
PMCID: PMC3830511  PMID: 24180481
Fibroblast growth factor-23; Coronary artery calcification; Vascular calcification; Hemodialysis
12.  Lowering vascular calcification burden in chronic kidney disease: Is it possible? 
World Journal of Nephrology  2013;2(3):49-55.
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.
PMCID: PMC3832912  PMID: 24255887
Coronary calcification; Coronary artery calcification; Renal failure; Phosphate; Vitamin D
13.  Coronary artery calcifications predict long term cardiovascular events in non diabetic Caucasian hemodialysis patients 
Aging (Albany NY)  2015;7(4):269-279.
Vascular calcifications are frequent in chronic renal disease and are associated to significant cardiovascular morbidity and mortality. The long term predictive value of coronary artery calcifications detected by multi-layer spiral computed tomography for major cardiovascular events was evaluated in non-diabetic Caucasian patients on maintenance hemodialysis free of clinical cardiovascular disease. Two-hundred and five patients on maintenance hemodialysis were enrolled into this observational, prospective cohort study. Patients underwent a single cardiac multi-layer spiral computed tomography. Calcium load was quantified and patients grouped according to the Agatston score: group 1 (Agatston score: 0), group 2 (Agatston score 1-400), group 3 (Agatston score 401-1000) and group 4 (Agatston score >1000). Follow-up was longer than seven years. Primary endpoint was death from a major cardiovascular event. Actuarial survival was calculated separately in the four groups with Kaplan-Meier method. Patients who died from causes other than cardiovascular disease and transplanted patients were censored. The “log rank” test was employed to compare survival curves. One-hundred two patients (49.7%) died for a major cardiovascular event during the follow-up period. Seven-year actuarial survival was more than 90% for groups 1 and 2, but failed to about 50% for group 3 and to <10% for group 4. Hence, Agatston score >400 predicts a significantly higher cardiovascular mortality compared with Agatston score <400 (p<0.0001); furthermore, serum Parathyroid hormone levels > 300 pg/l were associated to a lower survival (p < 0.05). Extended coronary artery calcifications detected by cardiac multi-layer spiral computed tomography, strongly predicted long term cardiovascular mortality in non-diabetic Caucasian patients on maintenance hemodialysis. Moreover, it was not related to conventional indices of atherosclerosis, but to other non-traditional risk factors, as serum Parathyroid hormone levels. A full cost-benefit analysis is however necessary to justify a widespread use of cardiac multi-layer spiral computed tomography in clinical practice.
PMCID: PMC4429091  PMID: 26131456
aging; cardiac calcifications; spiral computed tomography; mortality; morbidity; cardiovascular events; vascular pathology; endothelial cells; hemodialysis
14.  Cardiovascular risk markers associated with arterial calcification in patients with chronic kidney disease Stages 3 and 4 
Clinical Kidney Journal  2014;7(2):167-173.
The contribution of pro-inflammatory markers to cardiovascular (CV) risk and vascular calcification in chronic kidney disease (CKD) remains largely to be elucidated. We investigated the association between plasma levels of several biomarkers and calcification volume in three different vascular beds in CKD Stages 3 and 4 patients.
This is a cross-sectional, exploratory study in patients with an estimated glomerular filtration rate (eGFR) ≥20 and ≤45 mL/min/1.73 m2 and serum phosphorus ≥3.5 and <6.0 mg/dL enrolled in a previously published randomized, double blind, placebo-controlled single-centre trial. Ethylenediaminetetraacetic acid (EDTA) plasma samples were collected at baseline before patients received study medication and analysed for the presence of a number of biomarkers. Coronary artery calcium (CAC), thoracic aortic calcification (TAC) and abdominal aortic calcification (AAC) volumes were measured using standard electron-beam computed tomography protocols. Associations were adjusted for age, sex, smoking, body mass index, diabetes mellitus status, low-density lipoprotein cholesterol (LDL-C), systolic blood pressure and eGFR.
Associations with CAC were found for β2-microglobulin (B2M), fibroblast growth factor 23 (FGF23), interleukin-8 (IL-8) and IL-18. AAC was associated with: B2M, FGF23 and IL-2 receptor alpha (IL-2 RA). TAC was associated with: B2M, FGF23, IL-2 RA, IL-18 and tumour necrosis factor receptor type I. For most of the analysed biomarkers, there were non-significant trends of associations with calcification.
This exploratory study found that elevated plasma levels of several inflammatory biomarkers are significantly associated with arterial calcification in CKD Stages 3 and 4 patients. A greater understanding of inflammation and calcification in CKD patients may help the development of CV risk-assessment algorithms for better management of these patients.
PMCID: PMC3968563  PMID: 24683472
arterial calcification; biomarkers; cardiovascular risk; chronic kidney disease; inflammation
15.  Dissociation between progression of coronary artery calcification and endothelial function in hemodialysis patients: a prospective pilot study  
Clinical Nephrology  2011;78(1):1-9.
Chronic kidney disease profoundly disturbs calcium-phosphate metabolism and predisposes to premature atherosclerosis. Both coronary artery calcification (CAC) and endothelial dysfunction are common in hemodialysis (HD) patients. We hypothesized that a calcium-free phosphate binder would improve endothelial function and delay progression of vascular calcification in HD patients. Methods: This was a randomized parallel-group trial in HD patients comparing lanthanum carbonate (LC) with a non-LC phosphorus binders control group (non-LC) at a 1 : 1 randomization. CAC was obtained at baseline, 6, and 12 months, and endothelial function (brachial artery flow-mediated dilation – FMD) at baseline and 6 months. Results: 13 patients were randomized (LC n = 7 and non-LC n = 6). CAC scores (Log ± SE) at baseline were 7.21 ± 0.62 (LC) and 6.07 ± 0.73 (control). CAC increased in the non-LC group (33 ± 17% and 77 ± 22% at 6 and 12 months), but tended to decrease in the LC group (–10 ± 11% and –2 ± 11% at 6 and 12 months). There was statistically less progression in CAC in the LC group compared to control at 6 (p = 0.002) and 12 months (p = 0.003). There was no difference between groups in FMD (p = 0.7). Markers of inflammation did not change significantly. Conclusion: A slower rate of progression of CAC occurred in the LC group, independent of changes in FMD. This is the first study showing dissociation between progression of CAC and FMD in HD patients. Larger studies are warranted to elucidate the impact of different phosphate sequestration therapies on atherosclerosis in HD patients.
PMCID: PMC4407338  PMID: 22732331
phosphate binders; atherosclerosis; hemodialysis
16.  The prevalence of vascular calcification in patients with end-stage renal disease on hemodialysis: a cross-sectional observational study 
This multicenter international cross-sectional observational study characterized vascular and valvular calcification burden and correlations with pulse pressure, diabetes, hypertension, and cardiovascular diseases in prevalent hemodialysis patients.
We enrolled 275 consecutive adults with end-stage renal disease on maintenance hemodialysis for ⩾3 months. Coprimary endpoints were prevalences of: (1) echocardiographic calcification in mitral valve, aortic valve or mitral annulus; (2) aortoiliac tree vascular calcifications by plain lateral lumbar X-ray. Correlations among calcification sites and with demographics and comorbidities were determined. Pulse pressures were determined.
Subjects’ mean ± standard deviation (SD) age was 56 ± 15.9 years; mean (SD) dialysis duration was 4.5 ± 4.3 years. Overall, 100% of echocardiographically imaged patients (n = 243) had calcification in aortic valve, mitral valve, or mitral annulus; 77.8% of X-rayed patients (n = 248) had abdominal aortic calcification. Radiographic abdominal aortic calcification score correlated significantly with calcification of aortic valve (p < 0.0001) and mitral annulus (p = 0.0001) but not mitral valve. Aortic valve, mitral valve, and mitral annulus calcification correlated significantly among themselves (p < 0.0001). Moderate/severe aortic valve calcification was significantly more prevalent in patients aged ⩾65 years than <65 years, men than women, and Whites than African Americans. Pulse pressure correlated significantly with vascular calcification score (p = 0.0049) but not with valvular calcification at any site.
Vascular and valvular calcification are highly prevalent in the hemodialysis population. Peripheral vascular calcification correlates significantly with elevated pulse pressure and can be assessed easily using lateral lumbar X-ray. Further studies investigating the interaction between pulse pressure and development or progression of vascular calcification are of interest.
PMCID: PMC4416967  PMID: 25984289
chronic kidney disease; echocardiography; hemodialysis; lumbar X-ray; vascular calcification; valvular calcification
17.  Femoral bone mineral density reflects histologically determined cortical bone volume in hemodialysis patients 
We evaluated the associations between dual energy X-ray absorptiometry (DXA) and histologically determined cancellous and cortical bone volume by controlling for vascular calcifications and demographic variables in hemodialysis (HD) patients. Femoral bone mineral density (f-BMD) was associated with cortical porosity.
Assessment of bone mass in chronic kidney disease patients is of clinical importance because of the association between low bone volume, fractures, and vascular calcifications. DXA is used for noninvasive assessment of bone mass whereby vertebral results reflect mainly cancellous bone and femoral results reflect mainly cortical bone. Bone histology allows direct measurements of cancellous and cortical bone volume. The present study evaluates the association between DXA and histologically determined cancellous and cortical bone volumes in HD patients.
In 38 HD patients, DXA was performed for assessment of bone mass, anterior iliac crest bone biopsies for bone volume, and multislice computed tomography for vascular calcifications.
While lumbar bone mineral density (l-BMD) by DXA was not associated with histologically measured cancellous bone volume, coronary Agatson score showed a borderline statistically significant association (P=0.055). When controlled for age and dialysis duration, f-BMD by DXA was associated with cortical porosity determined by histology (P=0.005).
The usefulness of l-BMD for predicting bone volume is limited most probably because of interference by soft tissue calcifications. In contrast, f-BMD shows significant association with cortical porosity.
PMCID: PMC4501027  PMID: 19554246
Bone biopsy; Bone mineral density; Bone volume; Chronic kidney disease; Cortical porosity; Vascular calcifications
18.  Phosphorus Is Associated with Coronary Artery Disease in Patients with Preserved Renal Function 
PLoS ONE  2012;7(5):e36883.
High serum phosphorus levels have been associated with mortality and cardiovascular events in patients with chronic kidney disease and in the general population. In addition, high phosphorus levels have been shown to induce vascular calcification and endothelial dysfunction in vitro. The aim of this study was to evaluate the relation of phosphorus and coronary calcification and atherosclerosis in the setting of normal renal function. This was a cross-sectional study involving 290 patients with suspected coronary artery disease and undergoing elective coronary angiography, with a creatinine clearance >60 ml/min/1.73 m2. Coronary artery obstruction was assessed by the Friesinger score and coronary artery calcification by multislice computed tomography. Serum phosphorus was higher in patients with an Agatston score >10 than in those with an Agatston score ≤10 (3.63±0.55 versus 3.49±0.52 mg/dl; p = 0.02). In the patients with Friesinger scores >4, serum phosphorus was higher (3.6±0.5 versus 3.5±0.6 mg/dl, p = 0.04) and median intact fibroblast growth factor 23 was lower (40.3 pg/ml versus 45.7 pg/ml, p = 0.01). Each 0.1-mg/dl higher serum phosphate was associated with a 7.4% higher odds of having a Friesinger score >4 (p = 0.03) and a 6.1% greater risk of having an Agatston score >10 (p = 0.01). Fibroblast growth factor 23 was a negative predictor of Friesinger score (p = 0.002). In conclusion, phosphorus is positively associated with coronary artery calcification and obstruction in patients with suspected coronary artery disease and preserved renal function.
PMCID: PMC3349637  PMID: 22590632
19.  Malnutrition, a new inducer for arterial calcification in hemodialysis patients? 
Arterial calcification is a significant cardiovascular risk factor in hemodialysis patients. A series of factors are involved in the process of arterial calcification; however, the relationship between malnutrition and arterial calcification is still unclear.
68 hemodialysis patients were enrolled in this study. Nutrition status was evaluated using modified quantitative subjective global assessment (MQSGA). Related serum biochemical parameters were measured. And the radial artery samples were collected during the arteriovenous fistula surgeries. Hematoxylin/eosin stain was used to observe the arterial structures while Alizarin red stain to observe calcified depositions and classify calcified degree. The expressions of bone morphogenetic protein 2 (BMP2) and matrix Gla protein (MGP) were detected by immunohistochemistry and western blot methods.
66.18% hemodialysis patients were malnutrition. In hemodialysis patients, the calcified depositions were mainly located in the medial layer of the radial arteries and the expressions of BMP2 and MGP were both increased in the calcified areas. The levels of serum albumin were negatively associated with calcification score and the expressions of BMP2 and MGP. While MQSGA score, serum phosphorus and calcium × phosphorus product showed positive relationships with calcification score and the expressions of BMP2 and MGP.
Malnutrition is prevalent in hemodialysis patients and is associated with arterial calcification and the expressions of BMP2 and MGP in calcified radial arteries. Malnutrition may be a new inducer candidate for arterial calcification in hemodialysis patients.
PMCID: PMC3608064  PMID: 23506394
Arterial calcification; Hemodialysis; Malnutrition; Bone morphogenetic protein 2; Matrix Gla protein
20.  Biomarkers Associated with Vascular and Valvular Calcification in Chronic Hemodialysis Patients 
Disease markers  2013;34(4):229-235.
Background: Cardiovascular calcification, including arterial intimal and medial calcification (AIC and AMC) and valvular calcification (VC) are important predictors of outcome in chronic dialysis patients. We aimed to compare their prevalence and analyze respective risk factors in hemodialysis (HD) patients.
Methods: A total of 81 HD patients were enrolled. Vascular calcification was assessed by plain film radiography of the pelvis and VC was diagnosed by echocardiography. Demographic data was reviewed and serum levels of calcification-relevant biomarkers were determined. Patients with and without calcification were then compared.
Results: The prevalence study indicated that 36 patients had AIC (44.4%), 17 had AMC (21%) and 60 (74.1%) had VC. Patients with vascular calcification were older, and had a higher prevalence of diabetes. Their IL-6, osteoprotegerin, and uric acid levels were higher. Serum fetuin-A was lower in patients with VC. Logistic regression analysis revealed age, uric acid and diabetes to be independently associated with AIC; uric acid, diabetes and osteoprotegerin with AMC. Fetuin-A was the sole associate of VC.
Conclusions: It is concluded that the prevalence of cardiovascular calcification in chronic HD patients was high with cardiac valve involvement more frequent. Factors associated with different type of calcification were not identical. Changes in biomarkers may represent clinical clues for assessment of cardiovascular calcification in HD patients.
PMCID: PMC3810241  PMID: 23396289
Vascular calcification; valvular calcification; hemodialysis; biomarker
21.  Vitamin K-Antagonists Accelerate Atherosclerotic Calcification and Induce a Vulnerable Plaque Phenotype 
PLoS ONE  2012;7(8):e43229.
Vitamin K-antagonists (VKA) are treatment of choice and standard care for patients with venous thrombosis and thromboembolic risk. In experimental animal models as well as humans, VKA have been shown to promote medial elastocalcinosis. As vascular calcification is considered an independent risk factor for plaque instability, we here investigated the effect of VKA on coronary calcification in patients and on calcification of atherosclerotic plaques in the ApoE−/− model of atherosclerosis.
Methodology/Principal Findings
A total of 266 patients (133 VKA users and 133 gender and Framingham Risk Score matched non-VKA users) underwent 64-slice MDCT to assess the degree of coronary artery disease (CAD). VKA-users developed significantly more calcified coronary plaques as compared to non-VKA users. ApoE−/− mice (10 weeks) received a Western type diet (WTD) for 12 weeks, after which mice were fed a WTD supplemented with vitamin K1 (VK1, 1.5 mg/g) or vitamin K1 and warfarin (VK1&W; 1.5 mg/g & 3.0 mg/g) for 1 or 4 weeks, after which mice were sacrificed. Warfarin significantly increased frequency and extent of vascular calcification. Also, plaque calcification comprised microcalcification of the intimal layer. Furthermore, warfarin treatment decreased plaque expression of calcification regulatory protein carboxylated matrix Gla-protein, increased apoptosis and, surprisingly outward plaque remodeling, without affecting overall plaque burden.
VKA use is associated with coronary artery plaque calcification in patients with suspected CAD and causes changes in plaque morphology with features of plaque vulnerability in ApoE−/− mice. Our findings underscore the need for alternative anticoagulants that do not interfere with the vitamin K cycle.
PMCID: PMC3430691  PMID: 22952653
22.  Multidetector Computed Tomography for Coronary Artery Disease Screening in Asymptomatic Populations 
Executive Summary
This evidence-based health technology assessment systematically reviewed the published literature on multidetector computed tomography (MDCT) angiography (with contrast) as a diagnostic tool for coronary artery disease (CAD), and applied the results of the assessment to health care practices in Ontario.
Clinical Need
Coronary artery disease is the leading cause of death in the western world. Occlusion of coronary arteries reduces coronary blood flow and oxygen delivery to the myocardium (heart muscle). The rupture of an unstable atherosclerotic plaque may result in myocardial infarction. If left untreated, CAD can result in heart failure and, subsequently, death. According to the Heart and Stroke Foundation of Canada, 54% of all cardiovascular deaths are due to CAD. Patient characteristics (e.g., age, sex, and genetics), underlying clinical conditions that predispose to cardiac conditions (e.g., diabetes, hypertension, and elevated cholesterol), lifestyle characteristics, (e.g., obesity, smoking, and physical inactivity), and, more recently, determinants of health (e.g., socioeconomic status) may predict the risk of getting CAD.
In 2004/2005, The Ontario government funded approximately 15,400 percutaneous (through the skin) coronary interventions and 7,840 coronary bypass procedures for the treatment of CAD. These numbers are expected to reach 22,355 for percutaneous coronary interventions and 12,323 for coronary bypass procedures in 2006/2007. It was noted that more than one-half of all first coronary events occur in people without symptoms of CAD. In Ontario in 2000/2001, $457.9 million (Cdn) was spent on invasive ($237.4 million) and noninvasive ($220.5 million) cardiac services. The use of noninvasive cardiac tests, in particular, is rising rapidly.
The Technology
Computed tomography (CT) is a medical imaging method employing tomography where digital geometry processing is used to generate a 3-dimensional image of the internals of an object from a large series of 2-dimensional X-ray images taken around a single axis of rotation. Multidetector computed tomography is performed for noninvasive imaging of the coronary arteries. Computer software quantifies the amount of calcium within the coronary arteries and calculates a coronary artery calcium score.
Compared with conventional CT scanning, MDCT can provide smaller pieces of information and cover a larger area faster. Advanced MDCT technology (that is, 8-, 16-, 32-, and 64-slice systems) can produce more images in less time. For general CT scanning, this faster capability can reduce the length of time people are required to be still during the procedure and thereby reduce potential movement artifact. However, the additional clinical utility of images obtained from faster scanners compared with the images obtained from conventional CT scanners for current CT indications (i.e., nonmoving body parts) is unknown.
Review Strategy
The Medical Advisory Secretariat completed a computer-aided search limited to English-language studies in humans from 1998 to 2007 in multiple medical literature databases, including MEDLINE, EMBASE, The Cochrane Library, and INAHTA/CRD. Case reports, letters, editorials, nonsystematic reviews, and comments were excluded. Additional studies that met the inclusion and exclusion criteria were obtained from reference lists of included studies. Inclusion and exclusion criteria were applied to the results according to the criteria listed below.
The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to evaluate the overall quality of the body of evidence (defined as 1 or more studies) supporting the research questions explored in this systematic review.
Summary of Findings and Conclusions
Screening the asymptomatic population for CAD using MDCT does not meet World Health Organization criteria for screening; hence, it is not justifiable. Coronary artery calcification measured by MDCT is a good predictor of future cardiovascular events. However, MDCT exhibits only moderately high sensitivity and specificity for detection of CAD in an asymptomatic population. If population-based screening were implemented, a high rate of false positives would result in increased downstream costs and interventions. Additionally, some cases of CAD would be missed, as they may not be developed, or not yet have progressed to detectable levels. There is no evidence for the impact of screening on patient management. Cardiovascular risk factors are positively associated with the presence of coronary artery calcification and cardiovascular events; however, risk factor stratification to identify high-risk asymptomatic individuals is unclear given the current evidence-base.
Safety of MDCT screening is also an issue because of the introduction of increased radiation doses for the initial screening scan and possible follow-up interventions.
No large randomized controlled trials of MDCT screening have been published, which indicates an important area of future research.
Lastly, the policy implications for MDCT screening for CAD in the asymptomatic population are significant. There is no evidence on the long-term implications of screening, and the potential impact on the resources of the health care system is considerable.
PMCID: PMC3377586  PMID: 23074503
23.  Associations of fetuin-A and osteoprotegerin with arterial stiffness and early atherosclerosis in chronic hemodialysis patients 
BMC Nephrology  2013;14:122.
Cardiovascular morbidity and mortality remains excessive in patients with chronic kidney disease. The association of vascular changes with regulators of extraosseous calcification in this patient population is still under investigation. The aim of the present study was to investigate the associations of the calcification inhibitor fetuin-A, and the anti-osteoclastic factor osteoprotegerin (OPG) with vascular pathology in chronic hemodialysis patients.
In this cross-sectional study including 81 stable chronic hemodialysis patients, we measured carotid-to-femoral pulse wave velocity (cfPWV) with applanation tonometry, reflecting arterial stiffness, and common carotid intima-media thickness (ccIMT), a surrogate of early atherosclerosis, as well as serum levels of fetuin-A and OPG. Co-morbidities, traditional cardiovascular risk factors, inflammatory markers and mineral-bone disease serology parameters were also recorded.
cfPWV correlated inversely with fetuin-A (r=−0.355, p=0.001) and positively with OPG (r=0.584, p<0.001). In multilinear regression analysis including age, gender, diabetes, cardiovascular disease, hypertension, pulse pressure, LDL, logCRP, both fetuin-A and OPG were independently associated with cfPWV (p=0.024 and p=0.041 respectively). ccIMT was negatively associated with fetuin-A (r=−0.312, p=0.005) and positively with OPG (r=0.521, p<0.0001); however these associations lost statistical significance after adjustment for age.
In chronic hemodialysis patients both fetuin-A and OPG levels are independently associated with arterial stiffness but not with early atherosclerotic vascular changes.
PMCID: PMC3700830  PMID: 23758931
Intima-media thickness; Fetuin-A; Hemodialysis; Osteoprotegerin; Pulse wave velocity
24.  Calcium Balance and Negative Impact of Calcium Load in Peritoneal Dialysis Patients 
Like hemodialysis patients, peritoneal dialysis (PD) patients are facing an excessively increased burden of vascular and valvular calcification. According to some surveys, more than 80% of prevalent PD patients are complicated with vascular calcification, and more than one third have heart valve calcification.
Dysregulated phosphate metabolism is well recognized to play an important role in inducing vascular calcification, but increasing evidence is suggesting that dysregulated calcium metabolism also promotes vascular calcification and might in fact be more potent than phosphate in inducing that calcification. Growing evidence from randomized controlled trials shows more progression of vascular calcification and higher mortality among chronic kidney disease (CKD) patients receiving calcium-based phosphate binders than among those receiving non-calcium-containing phosphate binders. Those results raise important safety concern about the use of high-dose calcium-based phosphate binders in the CKD population, including both non-dialysis and dialysis patients (especially anuric dialysis patients), who have markedly reduced urinary calcium excretion. To prevent calcium overload, this review recommends restricting the dose of calcium-based phosphate binders in CKD patients, especially those who are elderly, who have increased cardiovascular risk, who already have baseline vascular or valvular calcification, or who have low intact parathyroid hormone and adynamic bone disease.
PMCID: PMC4079479  PMID: 24497596
Calcium balance; calcium-based phosphate binders; vascular calcification
25.  Predictive value of coronary calcifications for future cardiac events in asymptomatic patients with diabetes mellitus: A prospective study in 716 patients over 8 years 
To establish an efficient prophylaxis of coronary artery disease reliable risk stratification is crucial, especially in the high risk population of patients suffering from diabetes mellitus. This prospective study determined the predictive value of coronary calcifications for future cardiovascular events in asymptomatic patients with diabetes mellitus.
We included 716 patients suffering from diabetes mellitus (430 men, 286 women, age 55.2 ± 15.2 years) in this study. On study entry all patients were asymptomatic and had no history of coronary artery disease. In addition, all patients showed no signs of coronary artery disease in ECG, stress ECG or echocardiography. Coronary calcifications were determined with the Imatron C 150 XP electron beam computed tomograph. For quantification of coronary calcifications we calculated the Agatston score. After a mean observation period of 8.1 ± 1.1 years patients were contacted and the event rate of cardiac death (CD) and myocardial infarction (MI) was determined.
During the observation period 40 patients suffered from MI, 36 patients died from acute CD. The initial Agatston score in patients that suffered from MI or died from CD (475 ± 208) was significantly higher compared to those without cardiac events (236 ± 199, p < 0.01). An Agatston score above 400 was associated with a significantly higher annualised event rate for cardiovascular events (5.6% versus 0.7%, p < 0.01). No cardiac events were observed in patients with exclusion of coronary calcifications. Compared to the Framingham risk score and the UKPDS score the Agatston score showed a significantly higher diagnostic accuracy in the prediction of MI with an area under the ROC curve of 0.77 versus 0.68, and 0.71, respectively, p < 0.01.
By determination of coronary calcifications patients at risk for future MI and CD could be identified within an asymptomatic high risk group of patients suffering from diabetes mellitus. On the other hand future events could be excluded in patients without coronary calcifications.
PMCID: PMC2569906  PMID: 18847481

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