MO754: Impact of Calcium-to-Magnesium Ratio on Carotid Intima-Media Thickness—Cardiovascular Risk Assessment in Haemodialysis

Abstract

Abstract BACKGROUND AND AIMS Cardiovascular disease (CVD) is the leading cause of death in chronic kidney disease patients. The interaction between calcium and magnesium has been associated with several pathophysiological processes that occur in the vessel wall, such as endothelial dysfunction and vascular calcification. The aim of this study was to assess the relationship between calcium-to-magnesium (Ca: Mg) ratio and carotid intima-media thickness (CIMT), a widely used risk marker for CVD in the assessment of subclinical atherosclerosis. This study also aimed to establish the role of the Ca: Mg ratio as a predictor of cardiovascular mortality in haemodialysis (HD). METHOD Prevalent HD patients were enrolled in the longitudinal prospective study in a single tertiary centre. According to CIMT measured through B-mode ultrasound, the patients were divided into two groups: ≥0.9 mm (G1) and <0.9 mm (G2). Data from both groups were compared by Student's t-test. Partial correlation was used to assess the relationship between the variables under analysis and the CIMT, when controlled by dialysis time. The prevalence ratio of predictors of carotid thickening was calculated using a Poisson model with robust variance. Multivariable Cox regression analysis was performed to determine the predictive factors of cardiovascular death. RESULTS A total of 120 patients on HD were included with mean age 66.5 ± 13.97 years, 66.7% male. Magnesium (P < 0.001), Ca: Mg ratio (P < 0.001) and Adragão score (P <0.001) were statistically different between the two groups (Table 1). The partial correlation showed a strong positive association between CIMT and Ca: Mg ratio (r = 0.873; P <0.001) and a moderate association between CIMT and Adragão score (r = 0.614, P < 0.001), whereas there was a moderate negative correlation between CIMT and magnesium (r = –0.671, P <0.001). The Poisson model showed high prevalence of carotid thickening for higher values ​​of Ca: Mg ratio [aPR = 1.055, 95% confidence interval (95% Cl) 1.007–2.176] and Adragão score (aPR = 1.106, 95% Cl 1.006–1.351), and for lower magnesium values ​​(aPR = 0.462, 95% CI 0.248–0.861). Using the multivariate Cox model, age (HR = 1.045, 95% CI 1.012–1.084), Adragão score (HR = 1.078, 95% CI 1.006–1.234) and Ca: Mg ratio (HR = 1.154, 95% CI 1.098–2.236) were predictors of cardiovascular mortality. CONCLUSION In our population, the Ca: Mg ratio was a predictor of carotid thickening, so its monitoring can be useful to identify patients at higher cardiovascular risk. The Ca: Mg ratio was further validated as a predictor of cardiovascular mortality in HD patients. More studies are needed to better understand the relationship between this ratio and cardiovascular events.