Vascular Calcification In Chronic Kidney Disease
Vascular Calcification In Chronic Kidney Disease
Background: Vascular calcification (VC) and arterial stiffness are major contributors to cardiovascular (CV) disease in chronic kidney disease (CKD). Both are independent predictors of CV mortality and are inversely correlated with bone mineral density (BMD). Few studies have addressed the extent of VC in the pre-dialysis CKD population, with associated measurements of BMD and arterial compliance.
Methods: We report cross-sectional data on 48 patients with CKD (GFR 17-55 ml/min) assessing the prevalence of VC and its associations. All patients had computed tomography (CT) scans through abdominal aorta and superficial femoral arteries (SFAs) to determine VC, pulse wave velocity (PWV) using SphygmoCor device (AtCor PWV Inc., Westmead, Australia) measuring arterial stiffness, and dual-energy X-ray absorptiometry (DEXA) scans to determine BMD, as well as serum markers of renal function and mineral metabolism.
Results: Patients, 71% male, 54% diabetic, had a median age 64.5 years. Mean estimated GFR was 35.1 ± 10 ml/min. Mean PWV was 10.0 ± 4.5 m/s and mean aortic VC score was 421.5 ± 244 Hounsfield units, with 90% of subjects having some aortic VC present. In univariate linear regression analysis, aortic VC correlated positively with age (r 0.50, P < 0.001), triglycerides (r 0.47, P = 0.002) and PWV (r 0.33, P = 0.03). There was also greater VC with declining renal function (r −0.28, P = 0.05). There was no significant association between VC and serum markers of mineral metabolism, however phosphate and Ca × P correlated positively with PWV (r 0.35, P = 0.02, r 0.36, P = 0.02, respectively). There was also a positive association between PWV and triglycerides (P = 0.008), and a trend towards greater PWV with increasing age (P = 0.09). In multivariate regression analysis only increasing age and triglyceride levels were significantly associated with aortic VC and PWV. Mean spine and femoral T-scores on DEXA were 0.48 and −1.31 respectively, with 13% of subjects having femoral T-score <−2.5 (osteoporotic range). SFA VC inversely correlated with femoral T-scores (r −0.43, P = 0.004); however, there was a positive (likely false) association between spine T-scores and aortic VC (r 0.37, P = 0.01), related to the limitation of vertebral DEXA in CKD.
Conclusion: There is a high prevalence of VC in pre-dialysis CKD patients, worse with increasing age, triglycerides and reducing renal function. Correlation exists between VC and PWV and determination of one or both may be useful for CKD patient CV risk assessment. Femoral BMD is inversely associated with SFA VC, but measurement of vertebral BMD by DEXA is unreliable in CKD patients with aortic VC.
Cardiovascular (CV) disease is the leading cause of mortality in patients with chronic kidney disease (CKD) and up to 45% of pre-dialysis CKD patients may die before receiving dialysis. Although traditional CV risk factors are common in this population, much of the CV disease may relate to non-traditional CV risk factors such as vascular calcification (VC) and arterial stiffness. Although the presence of increased VC in patients with CKD has been known for some time, the extent to which VC impacts on CV disease and mortality has only recently been appreciated. Studies have reported increased VC in end-stage kidney disease (ESKD) compared to the general population, with the predominant differences being earlier age of onset and greater distribution. Studies involving VC measurement of CKD patients, not on dialysis, are limited but the prevalence of CV disease is also increased.
CKD patients also have stiffer vessels compared to the general population, contributing to reduced arterial compliance. In CKD there is a similar magnitude of atherosclerotic plaque burden and intimal thickness but markedly increased medial calcification (arteriolosclerosis). This phenomenon is a major determinant of left ventricular pressure overload and of abnormal coronary perfusion. The extent of VC and the degree of arterial stiffening, closely inter-related, are independent predictors of CV mortality in both the general and CKD populations. Again, there is limited available data about functional arterial wall properties in mild-to-moderate CKD.
A relationship also exists between increasing VC and loss of bone mineral density (BMD), with recent experimental studies revealing the mechanisms which link these two processes. In the general population and in CKD there is an association between CV mortality and osteoporosis and BMD has been shown to be inversely associated with both VC and arterial stiffness as measured by pulse wave velocity (PWV).
Few studies in CKD have looked at both structural and functional changes associated with VC and most studies independently addressing VC, arterial stiffness and BMD have looked at ESKD patients, with limited data in the pre-dialysis CKD population. We present cross-sectional data on a cohort of CKD patients, not on dialysis, outlining the prevalence and severity of VC and arterial stiffness. The aims of this study were to explore the relationship between VC, arterial compliance and BMD in CKD and to identify factors potentially related to each.
Background: Vascular calcification (VC) and arterial stiffness are major contributors to cardiovascular (CV) disease in chronic kidney disease (CKD). Both are independent predictors of CV mortality and are inversely correlated with bone mineral density (BMD). Few studies have addressed the extent of VC in the pre-dialysis CKD population, with associated measurements of BMD and arterial compliance.
Methods: We report cross-sectional data on 48 patients with CKD (GFR 17-55 ml/min) assessing the prevalence of VC and its associations. All patients had computed tomography (CT) scans through abdominal aorta and superficial femoral arteries (SFAs) to determine VC, pulse wave velocity (PWV) using SphygmoCor device (AtCor PWV Inc., Westmead, Australia) measuring arterial stiffness, and dual-energy X-ray absorptiometry (DEXA) scans to determine BMD, as well as serum markers of renal function and mineral metabolism.
Results: Patients, 71% male, 54% diabetic, had a median age 64.5 years. Mean estimated GFR was 35.1 ± 10 ml/min. Mean PWV was 10.0 ± 4.5 m/s and mean aortic VC score was 421.5 ± 244 Hounsfield units, with 90% of subjects having some aortic VC present. In univariate linear regression analysis, aortic VC correlated positively with age (r 0.50, P < 0.001), triglycerides (r 0.47, P = 0.002) and PWV (r 0.33, P = 0.03). There was also greater VC with declining renal function (r −0.28, P = 0.05). There was no significant association between VC and serum markers of mineral metabolism, however phosphate and Ca × P correlated positively with PWV (r 0.35, P = 0.02, r 0.36, P = 0.02, respectively). There was also a positive association between PWV and triglycerides (P = 0.008), and a trend towards greater PWV with increasing age (P = 0.09). In multivariate regression analysis only increasing age and triglyceride levels were significantly associated with aortic VC and PWV. Mean spine and femoral T-scores on DEXA were 0.48 and −1.31 respectively, with 13% of subjects having femoral T-score <−2.5 (osteoporotic range). SFA VC inversely correlated with femoral T-scores (r −0.43, P = 0.004); however, there was a positive (likely false) association between spine T-scores and aortic VC (r 0.37, P = 0.01), related to the limitation of vertebral DEXA in CKD.
Conclusion: There is a high prevalence of VC in pre-dialysis CKD patients, worse with increasing age, triglycerides and reducing renal function. Correlation exists between VC and PWV and determination of one or both may be useful for CKD patient CV risk assessment. Femoral BMD is inversely associated with SFA VC, but measurement of vertebral BMD by DEXA is unreliable in CKD patients with aortic VC.
Cardiovascular (CV) disease is the leading cause of mortality in patients with chronic kidney disease (CKD) and up to 45% of pre-dialysis CKD patients may die before receiving dialysis. Although traditional CV risk factors are common in this population, much of the CV disease may relate to non-traditional CV risk factors such as vascular calcification (VC) and arterial stiffness. Although the presence of increased VC in patients with CKD has been known for some time, the extent to which VC impacts on CV disease and mortality has only recently been appreciated. Studies have reported increased VC in end-stage kidney disease (ESKD) compared to the general population, with the predominant differences being earlier age of onset and greater distribution. Studies involving VC measurement of CKD patients, not on dialysis, are limited but the prevalence of CV disease is also increased.
CKD patients also have stiffer vessels compared to the general population, contributing to reduced arterial compliance. In CKD there is a similar magnitude of atherosclerotic plaque burden and intimal thickness but markedly increased medial calcification (arteriolosclerosis). This phenomenon is a major determinant of left ventricular pressure overload and of abnormal coronary perfusion. The extent of VC and the degree of arterial stiffening, closely inter-related, are independent predictors of CV mortality in both the general and CKD populations. Again, there is limited available data about functional arterial wall properties in mild-to-moderate CKD.
A relationship also exists between increasing VC and loss of bone mineral density (BMD), with recent experimental studies revealing the mechanisms which link these two processes. In the general population and in CKD there is an association between CV mortality and osteoporosis and BMD has been shown to be inversely associated with both VC and arterial stiffness as measured by pulse wave velocity (PWV).
Few studies in CKD have looked at both structural and functional changes associated with VC and most studies independently addressing VC, arterial stiffness and BMD have looked at ESKD patients, with limited data in the pre-dialysis CKD population. We present cross-sectional data on a cohort of CKD patients, not on dialysis, outlining the prevalence and severity of VC and arterial stiffness. The aims of this study were to explore the relationship between VC, arterial compliance and BMD in CKD and to identify factors potentially related to each.
