Development and Validation of Risk Models for Outcomes of Isolated Coronary Artery Bypass Grafting　- A Nationwide Analysis in Japan.

BACKGROUND: Reliable preoperative risk assessment is essential in cardiac surgery. In Japan, coronary artery bypass grafting (CABG) risk models have been developed from the Japan Cardiovascular Surgery Database - Adult section (JCVSD-A), with JapanSCORE I and II released previously. To reflect contemporary practice, we developed and validated JapanSCORE III, an updated risk model for isolated CABG, using JCVSD-A. METHODS AND RESULTS: We identified patients undergoing isolated CABG between 2018 and 2023 in the JCVSD-A. The dataset was temporally split into development (2018-2022) and validation (2023) cohorts. A least absolute shrinkage and selection operator model was developed to predict operative mortality, incorporating imaging-based predictors and clinically relevant factors. Secondary outcome models were constructed for stroke, reoperation, prolonged ventilation, renal failure, deep sternal wound infection (DSWI), gastrointestinal complications, and intensive care unit stay >7 days. Model performance was assessed by areas under the curve (AUC) and calibration plots. Among 70,180 patients (mean age 69.3 years; 20% women), operative mortality was 2.7%. The incidence of stroke, reoperation, prolonged ventilation, renal failure, DSWI, gastrointestinal complications, and prolonged ICU stay was 1.8%, 1.5%, 3.7%, 2.0%, 1.1%, 1.3%, and 13.2%, respectively. Operative mortality and renal failure models demonstrated good discrimination (AUC >0.8) and calibration in validation. CONCLUSIONS: Operative outcomes remained stable despite increasing predicted risk. The JapanSCORE III models showed good predictive performance, providing valid tools for preoperative risk stratification.