Mid-Term Mortality Prediction Using Four Established Risk Scores in Patients with Chronic Limb-Threatening Ischemia Undergoing Cardiac Surgery

<b>Objectives:</b> Patients with chronic limb-threatening ischemia (CLTI) represent a high-risk cohort for cardiac surgery due to the systemic atherosclerotic burden and frailty. This study aimed to evaluate the short- and mid-term prognoses of CLTI patients undergoing open cardiac surgery and to assess the prognostic utility of four risk scoring systems: Japan SCORE, SPINACH SCORE, Clinical Frailty Scale (CFS), and Geriatric Nutritional Risk Index (GNRI). <b>Methods:</b> We retrospectively analyzed 44 patients with CLTI who underwent open cardiac surgery between 2014 and 2023. Thirty-day and 1-year mortality were assessed. Patients were stratified using ROC-derived cutoffs for each scoring system. Kaplan-Meier survival curves and time-dependent ROC analyses were used to evaluate predictive performance over time. <b>Results:</b> Thirty-day mortality was significantly associated with a higher Japan SCORE; survivors had significantly lower scores than non-survivors (5.5% vs. 25.8%, <i>p</i> < 0.05). One-year mortality was significantly associated with nutritional status, as survivors showed a significantly higher GNRI than non-survivors (92.0 vs. 86.0, <i>p</i> < 0.05). Time-dependent ROC analysis revealed that the GNRI and SPINACH SCORE's sustained prognostic accuracy beyond 1 year. Calibration plots showed good agreement between predicted and observed probabilities for the SPINACH SCORE and GNRI, while decision curve analysis (DCA) demonstrated that these two models provided greater net clinical benefit across a range of thresholds, particularly in the 5-20% range. <b>Conclusions:</b> Japan SCORE is effective for short-term risk prediction, while SPINACH SCORE and GNRI offer superior prognostic value for mid-term outcomes. These scoring systems may support preoperative risk stratification and decision-making in CLTI patients undergoing cardiac surgery.