Evaluation of coronary artery calcification using multislice computed tomography in patients on dialysis: association with fetuin-A and osteoprotegerin

Introduction
Cardiovascular disease is the leading cause of mortality in patients with end-stage renal disease (ESRD) and is attributed to a combination of traditional and nontraditional risk factors. In recent years, there has been an increasing recognition of a very high prevalence of cardiovascular calcification in the ESRD population, including patients receiving hemodialysis (HD) and peritoneal dialysis. The mechanism is multifactorial, including structural and functional abnormalities in the large vessels, disorders in calcium (Ca) and phosphate (P) metabolism, vascular smooth muscle cells changes, and regulatory markers such as fetuin-A and osteoprotegerin (OPG).
Aim of the work
The aim of the present study was to determine the utility of multislice computed tomography (MSCT) for the assessment of coronary artery calcifications (CACs) and to identify the potential risks for CAC, including calcification regulating proteins such as fetuin-A and OPG, among patients with ESRD on maintenance dialysis (HD and peritoneal dialysis).
Patients and methods
This study included 70 patients who were divided into four groups: 20 patients on continuous ambulatory peritoneal dialysis (CAPD), 10 patients with ESRD stage 4 and 5, 30 patients on HD (subdivided into three subgroups according to the duration of HD: for 1–5 years, for 5–10 years, and for more than 10 years), and 10 healthy controls. They were subjected to complete history-taking, thorough clinical examination, investigations including serum level of fetuin-A, serum level of OPG by using the enzyme-linked immunosorbent assay technique, as well as MSCT imaging using 128-detector scanners for the quantification of CAC (calcium scoring) by using the Agatston method.
Results
There was a significant decrease in the serum level of fetuin-A in patients on HD compared with patients on CAPD, as well as in healthy controls. Moreover, there was a significant increase in the serum level of OPG in patients on HD compared with its level in CAPD patients as well as in healthy controls. The calcium scoring was significantly high in the HD group of patients (group IIa) ( = 0.032), with a low calcium score in CAPD patients group (group I) ( = 0.036) compared with healthy controls in group IV. CAC scoring was correlated positively and significantly with serum level of OPG in the total samples ( = 0.345* and = 0.0270). On the other hand, it was negatively and significantly correlated with the serum level of fetuin-A in the total samples ( = −0.411* and = 0.002).
Conclusion
Fetuin-A and OPG can be early and important markers of vascular calcifications in patients on dialysis; in addition, calcium scoring using MSCT provides a noninvasive method of assessment of the vascular calcification in these patients. Vascular calcification is more evident in patients on HD than in patients treated using CAPD; this can help in the selection of the modality of treatment of patients with ESRD, as well as early detection and prevention of cardiovascular (CVS) diseases in patients with ESRD treated with dialysis either HD or CAPD.