<jats:sec id="sec001"> <jats:title>Background</jats:title> <jats:p>Acute decompensated heart failure (ADHF) is a growing healthcare burden with increasing prevalence and comorbidities due to progressive aging society. Accumulating evidence suggest that low skeletal muscle mass has a negative impact on clinical outcome in elderly adult population. We sought to determine the significance of psoas muscle area as a novel index of low skeletal muscle mass in elderly patients with ADHF.</jats:p> </jats:sec> <jats:sec id="sec002"> <jats:title>Methods</jats:title> <jats:p>In this single-center retrospective observational study, we reviewed consecutive 865 elderly participants (65 years or older) who were hospitalized for ADHF and 392 were available for analysis (79 years [74–85], 56% male). Cross-sectional areas of psoas muscle at the level of fourth lumbar vertebra were measured by computed tomography and normalized by the square of height to calculate psoas muscle index (PMI, cm<jats:sup>2</jats:sup>/m<jats:sup>2</jats:sup>).</jats:p> </jats:sec> <jats:sec id="sec003"> <jats:title>Results</jats:title> <jats:p>Dividing the patients by the gender-specific quartile value (2.47 cm<jats:sup>2</jats:sup>/m<jats:sup>2</jats:sup> for male and 1.68 cm<jats:sup>2</jats:sup>/m<jats:sup>2</jats:sup> for female), we defined low PMI as the lowest gender-based quartile of PMI. Multiple linear regression analysis revealed female sex, body mass index (BMI), and E/e’, but not left ventricular ejection fraction, were independently associated with PMI. Kaplan-Meier analysis showed low PMI was associated with higher rate of composite endpoint of all-cause death and ADHF re-hospitalization (P = 0.033). Cox proportional hazard model analysis identified low PMI, but not BMI, was an independent predictor of the composite endpoint (Hazard ratio: 1.52 [1.06–2.16], P = 0.024).</jats:p> </jats:sec> <jats:sec id="sec004"> <jats:title>Conclusions</jats:title> <jats:p>PMI predicted future clinical adverse events in elderly patients with ADHF. Further studies are needed to assess whether low skeletal muscle mass can be a potential therapeutic target to improve the outcome of ADHF.</jats:p> </jats:sec>