Background: Frailty influences the postoperative outcomes in patients undergoing left ventricular assist device (LVAD) implantation; however, a quantitative evaluation method has not been established. The purpose of the present study was to evaluate whether preoperative ESM mass is associated with short- and long-term clinical outcomes in patients with LVAD. Methods: A total of 119 consecutive patients with LVAD were enrolled between January 2010 and October 2017 at a single heart center. The ESM index and Hounsfield units (HU) of the ESM were calculated by computed tomography for preoperative ESM mass evaluation. We then statistically evaluated the in-hospital mortality, major adverse cardiovascular events (MACE), duration of hospital stay, and long-term survival. Results: In a multivariate Cox regression analysis, ESM index and HU of the ESM indicated no effect on the in-hospital mortality, MACE, and long-term survival. In addition, the ESM index presented a weak but significant negative linear correlation only with the duration of hospital stay (r = -0.21, p < 0.05). In contrast, the model for end-stage liver disease (MELD) score and preoperative venous-arterial extracorporeal membrane oxygenation (va-ECMO) were significant predictive factors for in-hospital mortality (MELD score: p < 0.001, hazard ratio [HR] 1.1; preoperative va-ECMO: p < 0.01, HR 2.72) and MACE (MELD score: p < 0.001, HR 1.07; preoperative va-ECMO: p < 0.005, HR 2.62). Conclusion: Preoperative ESM mass might predict the length of hospital stay in patients undergoing LVAD implantation. In contrast, it had no effect on MACE, in-hospital mortality, or long-term survival in this study.