Background: Insulin resistance (IR) is a central contributor to the development of both atherosclerotic disease and myocardial dysfunction. Triglyceride-glucose (TyG) index has gained prominence due to its simplicity and reliability. Concurrently, global longitudinal strain (GLS) has emerged as a highly sensitive parameter for the early diagnosis of subclinical left ventricular (LV) systolic impairment. Within the clinical landscape of non-ST elevation acute coronary syndrome (NSTE-ACS), early identification of cases predisposed to heart failure (HF) remains a significant diagnostic hurdle. This investigation explored the association between the TyG index and LV GLS in cases diagnosed with NSTE-ACS, utilizing speckle-tracking echocardiography as the primary assessment modality. Methods: This prospective cohort study was done at Benha University Hospital, including 315 cases admitted with NSTE-ACS between November 2023 and November 2024. Cases were divided into two groups: Group I (TyG index < 8.47) and Group II (TyG index ≥ 8.47).Results: The TyG index showed a strong inverse correlation with GLS (r = -0.673, P