Abstract： Objective:To analyze the association between the transverse area of erector spine muscle at T 12 level and prognosis in elderly patients with acute coronary syndrome (ACS). Methods:This was a prospective cohort study. Clinical data of elderly patients with ACS admitted to the coronary care unit or the emergency intensive care unit in Beijing Bo'Ai Hospital from January 2019 to June 2022. Blood routine and biochemical indicators were detected and echocardiography was performed within 24 hours after admission, chest CT examination was completed and the cross-sectional areas of the left and right vertical spinalis muscles were calculated at T 12 level, thrombolysis in myocardial infarction (TIMI) was performed within 24 hours after admission. The occurrence of major adverse cardiovascular and cerebral events (MACCE) within 12 months was followed up. The differences of clinical data and laboratory indexes between the MACCE group and the non-MACCE group were compared. Multivariable logistic regression model was used to analyze the association between the cross-sectional area of vertical spinal muscle at T 12 level and the occurrence of MACCE within 12 months after ACS. Results:A total of 406 patients were enrolled in the study, the incidence of MACCE within 12 months was 22.2%. The cross-sectional area of erector spine muscle at T 12 level [(20.43±3.51) cm 2vs. (24.36±3.66) cm 2, (Z=4.412, P<0.001)] in the MACCE group was lower than that in the non-MACCE group. Logistic regression analysis showed that after adjusting for sex, age, body mass index (BMI), TIMI score and revascularization, the cross-sectional area of erector spine muscle at T 12 level ( OR = 0.883, 95% CI: 0.803-0.971, P=0.010) was independently associated with MACCE within 12 months after ACS. Conclusion:The transverse area of vertical spinal muscle at T 12 level can be used as an independent predictor of MACCE within 12 months in elderly patients with ACS.