Preoperative Prediction Models for 30‐Day All‐Cause Mortality After Mitral Valve Repair in Dogs: A Single‐Center Retrospective Cohort Study

ABSTRACT Background Mitral valve repair (MVR) has emerged as a novel surgical intervention for dogs with myxomatous mitral valve disease (MMVD). However, no objective risk assessment method has been established for these cases. Objectives The primary aim of this study was to develop and evaluate preoperative prediction models for 30‐day postoperative mortality in dogs undergoing MVR. The secondary aim was to assess the association between short‐term predictive risk and long‐term mortality following MVR. Animals A total of 2089 client‐owned dogs with MMVD that underwent MVR between 2016 and 2023 were included. Methods This was a single‐center retrospective cohort study. Preoperative variables including demographic data, routine blood test results, diagnostic imaging examination data, and medication history were selected as predictor candidates. Prediction models for 30‐day all‐cause mortality were developed using these variables and shrinkage estimation methods, and the model performances were evaluated. The association between the predicted probabilities and 2‐year cumulative all‐cause mortality was assessed using Cox proportional hazards analysis. Results The 30‐day all‐cause mortality rate after MVR was 4.9% (102/2089). The best preoperative prediction model for 30‐day all‐cause death demonstrated low‐to‐moderate discrimination abilities (c‐statistics, 0.654) and good calibration performance (slope = 1.003; intercept = 0.007; Eavg = 0.002) in internal validation. The quartile grouping of the predicted 30‐day all‐cause mortality risk was associated with 2‐year mortality. Conclusions and Clinical Importance The preoperative prediction model for short‐term mortality in dogs undergoing MVR demonstrated acceptable predictive performance. The prediction model may provide an objective preoperative risk assessment in dogs undergoing MVR at this center.