Comparison of epicardial fat volume with parenchymal findings in systemic sclerosis patients

Purpose: The aim of this study was to determine whether epicardial fat volumes, in patients with systemic sclerosis (SSc), are associated with the presence of interstitial lung disease and the severity and extent of the disease defined by the findings of pulmonary involvement. Thus, it was aimed to determine whether epicardial fat volume could be used as a potential imaging marker for the severity of the disease defined by the findings of pulmonary involvement. Materials and Methods: In this study, 45 (40 females, 5 males, mean age 53,4 years) SSc patients who applied to Necmettin Erbakan University Meram Faculty of Medicine Rheumatology Outpatient Clinic between the dates 01.01.2020-30.06.2022, and 30 (25 females, 5 males, mean age 51,033 years) controls who applied to the polyclinic between the same dates and weren't diagnosed with any rheumatological diseases and coronary artery disease were included. Demographic, clinical and laboratory findings of patients obtained from patient files and electronic medical records of the hospital were evaluated retrospectively. In this study, the necessary data to calculate Warrick score, which was used to assess pulmonary involvement based on lung parenchymal abnormalities detected on thorax CT scans, were recorded and the score was calculated. Epicardial fat volume was measured, using the free and publicly available 3D Slicer program, on thorax CT images. Additional CT findings were recorded. Results: Interstitial lung disease was detected in 25 (55%) of SSc patients on CT. The mean age of patients with interstitial lung disease was 58, and the mean age of patients without interstitial lung disease was 47,65. The mean age of patients with interstitial lung disease was found to be higher than those without interstitial lung disease and the controls. The most common parenchymal findings, scored using the Warrick score, were septal/subpleural lines (96%) and irregular pleural margins (96%). The most common form of interstitial lung disease detected on CT was nonspecific interstitial pneumonia (84%). The mean scores of the patients involved in our study were 5,88 ± 2,53837 for the severity score, 6,8 ± 1,73205 for the extent score, 1,32 ± 1,81934 for the alveolar index, 11,36 ± 4,10163 for the fibrosis index, 12,68 ± 3,90214 for the total Warrick score. The mean epicardial fat volume was 72,4441 ± 45,26306 cm³ in SSc patients, 84,8191 ± 48,90193 cm³ in patients with interstitial lung disease, 56,9754 ± 35,64222 cm³ in patients without interstitial lung disease, and 41,7268 ± 21,79251 cm³ in controls. Epicardial fat volumes measured in SSc patients were found to be significantly higher than in the controls (p<0,001). Epicardial fat volumes in patients with interstitial lung disease were found to be significantly higher than in patients without interstitial lung disease and the controls (p<0,001). There was no significant correlation between epicardial fat volumes and the calculated scores (the severity score, the extent score, the total Warrick score, the alveolar index, the fibrosis index) of interstitial lung disease (p>0,05). A moderately positive significant correlation was found between the total Warrick score and the patient's creatinine value (0,7268 ± 0,16155 mg/dL) in the group with interstitial lung disease (r=0,403, p=0,045). Anti-Scl 70 antibody positivity (80%) was significantly higher in the group with interstitial lung disease than in the group without interstitial lung disease (30%) (chi-square=10,90, p<0,001). The widest esophageal diameter (28,68 ± 13,03112 cm), blood leukocyte count (8,9752 ± 3,36933 10^3/uL), blood neutrophil count (6,44 ± 2,8482 10^3/uL), blood platelet count (302.44 ± 89,03795 10^3/uL), modified Rodnan skin score (22,2 ± 13,94931), echocardiographic measurement of pulmonary artery pressure (38,36 ± 10,18937 mmHg) and the age at diagnosis (52,12 ± 12,02192) were found to be significantly higher in patients with interstitial lung disease than the widest esophageal diameter (16,15 ± 5,67798 cm), blood leukocyte count (6,6585 ± 1,74847 10^3/uL), blood neutrophil count (4,3715 ± 1,59150 10^3/uL), blood platelet count (247,7 ± 74,70651 10^3/uL), modified Rodnan skin score (12,45 ± 10,40989), echocardiographic measurement of pulmonary artery pressure (31,4 ± 6,97665 mmHg) and the age at diagnosis (43,85 ± 11,41686) in patients without interstitial lung disease (p<0,05). Conclusions: In our study, a statistically significant association was found between increased epicardial fat volumes and the presence of SSc, as well as with the presence of interstitial lung disease in patients with SSc. However, no correlation was found between epicardial fat volumes and the severity or extent of interstitial lung disease in this study. Keywords: Systemic Sclerosis, Epicardial Fat Volume, Epicardial Adipose Tissue, Interstitial Lung Disease, Computed Tomography