#2610 Low skeletal muscle mass and low skeletal muscle quality are associated with thoracic aorta calcification in dialysis patients
Authors: Wang Xiaoxu , Wang Bin , Zhang Xiao Liang 
Published: May 2024

Abstract

Background and Aims
Cardiovascular disease (CVD) is the leading cause of mortality in dialysis patients. Thoracic aorta calcification (TAC) is a common cardiovascular complication in dialysis patients and is independently associated with CVD. Sarcopenia, particularly low skeletal muscle mass, has been found to be associated with increased cardiovascular risk in dialysis patients. This study aims to explore the relationship between skeletal muscle quality and skeletal muscle mass at the first lumbar vertebra (L1) level determined by opportunistic CT scans (chest CT) and TAC, with the goal of providing valuable opportunities for identifying and intervening in high-risk CVD patients.

Method
We included 2514 patients for cross-sectional analysis, who underwent dialysis in four centers in China from 2020 to 2023 and all had chest CT scans including the L1 level. Additionally, we conducted a follow-up study on TAC in patients who initiated dialysis between 2014 and 2019 as part of the earlier research, including 215 patients who had undergone at least two chest CT scans for cohort analysis. At the L1 level, we assessed skeletal muscle quality [by skeletal muscle density (SMD), HU] and skeletal muscle mass [by skeletal muscle index (SMI), cm2/m2] in dialysis patients. Measurements of thoracic aorta calcification scores (TACS) and calcification scores for three segments of the thoracic aorta, including ascending aorta calcification score (ATACS), aortic arch calcification score (AoACS), and descending thoracic aorta calcification score (DTACS), were obtained in dialysis patients. Patients were divided based on their annual calcification score growth rate: those with a rate greater than or equal to the average annual increase were classified into the rapid progression group, while those with a rate less than the average were classified into the slow progression group (including those with no progression). Multivariable linear regression models were employed to assess the relationships between SMI and SMD with TACS. Multivariable logistic regression models were used to evaluate the associations of SMl and SMD with the risk of rapid progression of TACS.

Results
The mean (SD) age of participants was 56 (15) years, with 58.2% being male. The prevalence of TAC was 82.2%, while the prevalence of ascending thoracic aorta calcification (ATAC), aortic arch calcification (AoAC), and descending thoracic aorta calcification (DTAC) was 21.4%, 75.3%, and 68.8%, respectively. Over an average follow-up period of 3.22 years, the progression rate of TAC was 85.6%. Comparing the highest quartile of SMD to the lowest quartile, a significant inverse association was observed with TAC (beta −1.19, 95% CI −1.55— −0.83; P &lt; 0.001). Similarly, comparing the highest quartile of SMI to the lowest quartile, a significant inverse association was found with TAC (beta −0.59, 95% CI −0.92— −0.26; P = 0.001). SMI and SMD, as continuous variables, were both significantly negatively correlated with TAC. Higher SMD was associated with a reduced risk of rapid progression of TAC; after full adjustment, for every 1 SD increase in SMD, the risk of TAC rapid progression decreased by 46% (aOR 0.54, 95% CI 0.32—0.91; P = 0.021). SMI showed no significant association with the rapid progression of TAC. The associations of SMI and SMD with AoAC and DTAC were consistent with their associations with TAC, except for ATAC. The ROC curve analysis indicated that incorporating SMD into the model enhanced the discriminative ability for stratifying the risk of rapid progression of thoracic aorta calcification.

Conclusion
After adjusting for cardiovascular risk factors and inflammatory markers, higher skeletal muscle quality and higher skeletal muscle mass were significantly associated with lower TAC. Improving skeletal muscle quality in initial dialysis patients may reduce the risk of rapid TAC progression.