Abstract
BACKGROUND: Systemic sclerosis (SSc) patients face greater odds of developing cardiovascular disease. In this study, patient clinical characteristics, coronary artery calcium score (CACS) values, and epicardial fat volume (EFV) were analyzed to identify predictors of major adverse cardiovascular events (MACE) among SSc patients without pulmonary arterial hypertension (PAH). METHODS: This study enrolled 202 SSc patients and 202 controls from the First Affiliated Hospital of Ningbo University. SSc patients were separated into two groups based on their MACE status. The relationship between EFV and MACE incidence was assessed with Kaplan-Meier curves and Cox proportional hazards regression models, calculating hazard ratios (HRs) and 95% confidence intervals (CIs). Discrimination efficiency was evaluated based on global chi-square, concordance index (C-index), net reclassification index (NRI), and integrated discrimination improvement (IDI) index results. The incremental value of EFV as a predictor of MACE incidence was analyzed among these SSc patients. RESULTS: SSc patients presented with higher CACS values relative to controls {33.5 [interquartile range (IQR), 0-128.5] vs. 0 (IQR, 0-88.25), P=0.006}, and EFV was similarly elevated among SSc patients [120 (IQR, 93.5-148.5) vs. 110 (IQR, 89.5-142.5), P=0.037]. These patients underwent follow-up for a median of 48 (IQR, 36-60) months, during which 25.2% (51/202) of these patients experienced MACEs. The mean CACS value among MACE patients was significantly higher than that for non-MACE patients [88 (IQR, 19-144) vs. 0 (IQR, 0-123), P=0.003], as was the mean EFV [160 (IQR, 138-192) vs. 110 (IQR, 84-130), P<0.001]. Multivariable Cox regression revealed that EFV was independently associated with the risk of MACE incidence (HR: 1.027, 95% CI: 1.015-1.041, P=0.001). Time-dependent Youden index analyses revealed that the optimal EFV cut-off for the prediction of MACE incidence was 126 cm(3), and this value was therefore used to separate participants into groups with low and high EFV levels. Kaplan-Meier analyses demonstrated that relative to low-EFV patients, high-EFV patients exhibited significantly lower MACE-free survival (P<0.01). EFV values were found to aid in the prediction of MACE incidence more effectively when combined with traditional risk factors, increasing the C-index from 0.77 to 0.84 (P<0.01), with a corresponding increase in the global c(2) from 45.2 to 52.2 (P<0.01), and corresponding significant increases in IDI and NRI values (0.12 and 0.46, respectively, both P<0.01). CONCLUSIONS: High EFV levels are independently associated with MACE risk among SSc patients, with poorer prognostic outcomes being evident among patients with SSc even if they were unaffected by PAH. The introduction of EFV offers incremental utility over traditional risk factors alone for the prediction of MACE incidence.