Both low appendicular skeletal muscle index (ASMI) and specific abdominal fat composition [i.e., increased visceral to subcutaneous (V/S) fat ratio] have been associated with cardiovascular events. However, the combined impact of these 2 components on long-term outcomes remains unclear, especially in patients with ST-segment elevation myocardial infarction (STEMI). In 303 patients with STEMI, ASMI and V/S fat ratio were assessed using dual-energy X-ray absorptiometry and abdominal computed tomography. Based on the criteria of the Asian Working Group for Sarcopenia and median of V/S fat ratio, sarcopenic obesity (SO) pattern was defined as low ASMI with high V/S fat ratio. The primary endpoint was composite outcomes of all-cause death, myocardial infarction, ischemic stroke, hospitalization for heart failure and unplanned revascularization. During a median follow-up of 3.9 years, primary endpoint occurred in 67 patients. Patients with an SO pattern showed significantly lower event-free survival rate compared with those without (p=0.006 by log-rank). Notably, when stratified by median age (67 years), this trend was particularly prominent in the younger-age group (p <0.001), but not significant in the older-age group (p=0.38). In the younger-age group, the multivariate analysis revealed that patients with SO pattern had a 2.97 (1.10-7.53) fold higher risk for primary endpoints compared with those without. Low ASMI with high V/S fat ratio, or so-called sarcopenic obesity, was associated with poor prognosis after STEMI, particularly in younger-age patients. The combined assessment of skeletal muscle with abdominal fat distribution may help stratify the risk among patients with STEMI, rather than each component alone. Copyright © 2021 Elsevier B.V. All rights reserved.