Association of pectoralis major muscle cross-sectional area and mean density on chest CT with mortality in elderly COVID-19 patients: sex and side differences

COVID-19 is a disease that primarily affects the lungs and may follow a fatal course. The aim of this study was to investigate whether there are differences in the cross-sectional area and mean density of the pectoralis major (PM), an accessory respiratory muscle, between survivors and non-survivors with COVID-19, with analyses performed according to sex. This retrospective study included a total of 201 patients aged 65 and over who were admitted to a tertiary healthcare center between March 2020 and May 2021. Patients with confirmed COVID-19 diagnosis by PCR and radiological evidence of pulmonary involvement on chest CT were included in the study, while patients with imaging artifacts that could affect measurements were excluded. The cross-sectional area and mean density of the right and left pectoralis major muscles were measured on axial CT images at the sternal angle level using 3D Slicer software. Of the 201 patients, 103 (51.2%) died. In the overall cohort, PM CSA (cross-sectional area) and density did not differ significantly between survivors and non-survivors. However, sex-stratified analyses revealed that female survivors had significantly greater right and left PM CSA compared to non-survivors (p = 0.015 for both), whereas in male patients, left PM density was significantly higher in survivors (p = 0.011). Lymphopenia and elevated NLR, AST, LDH, CRP, and D-dimer were also associated with mortality (p < 0.05). PM muscle measurements on chest CT showed some sex-related differences between survivors and non-survivors in elderly COVID-19 patients. Lower PM CSA in women and lower PM density in men were observed in univariable analyses. However, these parameters were not independently associated with mortality after adjustment. Therefore, PM muscle assessment on routine chest CT may provide additional but limited prognostic information.