Thoracic Skeletal Muscle Attenuation Predicts Sex-Specific Mortality After Coronary Artery Bypass Grafting—Sex-Specific Insights into Risk Stratification and Frailty Assessment

Figures

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  Figure 1. Study design and analytical workflow. Overview of the study population, preoperative thoracic CT assessment, HUAC measurement at TH4 and TH12, sex-specific classification, clinical outcome assessment, and statistical analyses. Abbreviations: CABG = coronary artery bypass grafting; CT = computed tomography; HUAC = Hounsfield Unit Average Calculation; TH = thoracic vertebral level; IPW = inverse probability weighting; ROC = receiver operating characteristic; AUC = area under the curve; HR = hazard ratio; CI = confidence interval.

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  Figure 2. Overall Kaplan–Meier Survival According to HUAC at TH4 and TH12. Kaplan–Meier survival curves for all-cause mortality according to thoracic muscle attenuation (HUAC) measured at TH4 and TH12. Patients in the lower HUAC quartile (sarcopenic group) showed reduced 1-, 3-, and 5-year survival after CABG compared with higher quartiles. Abbreviations: HUAC = Hounsfield Unit Average Calculation; TH4 = fourth thoracic vertebra; TH12 = twelfth thoracic vertebra; CABG = coronary artery bypass grafting.

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  Figure 3. Kaplan–Meier Survival According to HUAC at TH4 Stratified by Sex. Kaplan–Meier survival according to HUAC at TH4, stratified by sex. In both men and women, lower HUAC was associated with increased long-term mortality, with greater separation of the survival curves observed in women. Abbreviations: HUAC = Hounsfield Unit Average Calculation; TH4 = fourth thoracic vertebra.

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  Figure 4. Kaplan–Meier Survival According to HUAC at TH12 Stratified by Sex. Kaplan–Meier survival according to HUAC at TH12, stratified by sex. Low HUAC at TH12 predicted poorer long-term survival, particularly among women. Abbreviations: HUAC = Hounsfield Unit Average Calculation; TH12 = twelfth thoracic vertebra.

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  Figure 5. ROC Curves for HUAC at TH4 and TH12 in Female CABG Patients. Receiver-operating-characteristic (ROC) curves for HUAC measured at the fourth and twelfth thoracic vertebral levels in women. HUAC at TH4 showed higher AUC values for 1- and 3-year survival than TH12. Abbreviations: HUAC = Hounsfield Unit Average Calculation; TH = thoracic vertebra; AUC = area under the curve; ROC = receiver-operating-characteristic; CI = confidence interval.

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  Figure 6. ROC Curves for HUAC at TH4 and TH12 in Male CABG Patients. Receiver-operating-characteristic (ROC) curves for HUAC measured at TH4 and TH12 in men. Predictive accuracy was lower than in women, with HUAC TH4 outperforming TH12 but with weaker overall discrimination. Abbreviations: HUAC = Hounsfield Unit Average Calculation; TH = thoracic vertebra; AUC = area under the curve; ROC = receiver-operating-characteristic; CI = confidence interval.

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  Figure 7. Sex-Specific Cox Regression Models for Mid- and Long-Term Mortality After CABG. Unweighted and inverse-probability-weighted (IPW) Cox regression models for 1-, 3-, and 5-year all-cause mortality according to HUAC at TH4 and TH12. Hazard ratios (HR) and 95% confidence intervals (CI) are shown for the lower HUAC quartile versus all others. Abbreviations: HUAC = Hounsfield Unit Average Calculation; TH = thoracic vertebra; CABG = coronary artery bypass grafting; IPW = inverse probability weighting; HR = hazard ratio; CI = confidence interval.