Objective: To investigate the independent association between the triglyceride-glucose (TyG) index and subclinical left ventricular (LV) systolic dysfunction, and to analyze its impact on left ventricular global longitudinal strain (GLS) and myocardial work indices. Methods: A total of 103 patients admitted between August 2024 and February 2025 were enrolled. Clinical parameters, biochemical indicators, and echocardiographic data were collected, and the TyG index was calculated. GLS and LV myocardial work parameters (global work index, GWI; global constructive work, GCW; global wasted work, GWW; global work efficiency, GWE) were obtained using GE EchoPAC software. Multivariate logistic regression analysis was employed to assess the independent association between the TyG index and impaired LV function. Receiver operating characteristic (ROC) curves were plotted to evaluate the predictive efficacy of the TyG index for LV dysfunction, calculating the area under the curve (AUC), optimal cutoff value, sensitivity, and specificity. Results: The high-TyG group exhibited significantly higher prevalence rates of hypertension (67.31% vs. 43.14%), diabetes (42.31% vs. 7.84%), and dyslipidemia (34.62% vs. 3.92%) (all P < 0.05). Compared to the low-TyG group, the high-TyG group showed reduced absolute GLS (-17.60 ± 2.65 vs. -19.82 ± 2.12), lower GWI (1672.33 ± 308.58 vs. 1932.31 ± 280.26 mmHg%), and decreased GCW (1999.46 ± 324.11 vs. 2299.20 ± 323.32 mmHg%) (all P < 0.001). After adjusting for age, sex, body mass index (BMI), blood pressure, dyslipidemia, and other confounders, an elevated TyG index remained an independent risk factor for reduced GLS (OR = 2.982, 95% CI: 1.182-7.522, P = 0.021), reduced GWI (OR = 3.168, 95% CI: 1.302-7.706, P = 0.011), and diminished GCW (OR = 2.836, 95% CI: 1.250-7.309, P = 0.021). ROC analysis demonstrated the predictive efficacy of the TyG index for reduced GLS, GWI, and GCW, with AUC values of 0.725, 0.697, and 0.683, respectively. Conclusion: An elevated TyG index is independently associated with impaired LV global strain and myocardial work capacity, serving as a potential biomarker for subclinical LV dysfunction. This highlights its clinical utility in early risk assessment for metabolic cardiovascular diseases.