Predictive Value of the Baseline Tricuspid Annular Plane Systolic Excursion/Pulmonary Artery Systolic Pressure Ratio for Low Cardiac Output Syndrome After Coronary Artery Bypass Grafting in Patients With Coronary Artery Disease and Reduced Ejection F

Background: Patients with coronary artery disease and reduced ejection fraction, defined as a left ventricular ejection fraction (LVEF) <50%, have a high incidence of low cardiac output syndrome (LCOS) after coronary artery bypass grafting (CABG). Preoperative risk assessment remains largely based on left ventricular parameters, such as LVEF, whereas the predictive value of right ventricular–pulmonary arterial (RV-PA) coupling has not been systematically evaluated. Thus, this study aimed to investigate the predictive value of the preoperative tricuspid annular plane systolic excursion-to-pulmonary artery systolic pressure ratio (TAPSE/PASP) for LCOS after CABG in this population. Methods: We retrospectively included 307 patients with coronary artery disease who underwent isolated CABG between February 2021 and February 2025 and had a preoperative LVEF <50%. The primary endpoint was LCOS within 72 h after surgery. Multiple logistic regression was used to assess the independent association between TAPSE/PASP and LCOS. Receiver operating characteristic (ROC) curves were used to compare the discriminative performance of echocardiographic parameters, and the DeLong test was used to evaluate the incremental predictive value of adding TAPSE/PASP to the baseline clinical model. Internal validation was performed using 1000 bootstrap resamples. Results: Among the 307 patients, 101 (32.9%) developed postoperative LCOS. TAPSE/PASP was lower in the LCOS group than in the non-LCOS group: 0.28 (0.22–0.36) vs 0.47 (0.38–0.57) mm/mmHg; p < 0.001. Multiple logistic regression showed that each 0.1-unit increase in TAPSE/PASP was associated with a lower risk of LCOS after adjustment for age, sex, body mass index (BMI), New York Heart Association (NYHA) functional class, LVEF, chronic kidney disease, recent acute coronary syndrome, and coronary lesion characteristics (odds ratio (OR) = 0.62; 95% confidence interval (CI), (0.50–0.77); p < 0.001). This association remained stable in sensitivity analyses incorporating surgical strategy, mitral regurgitation (MR) severity, and ischemic/functional MR; in the MR-adjusted model, the OR was 0.64 (95% CI, 0.51–0.80); p < 0.001. Quartile-based analysis showed a stepwise decrease in LCOS incidence with increasing TAPSE/PASP, from 59.7% in the first quartile (Q1) to 11.7% in the fourth quartile (Q4) (trend test p < 0.001). Among individual echocardiographic parameters, TAPSE/PASP had an area under the receiver operating characteristic curve (AUC) of 0.810 (95% CI, 0.758–0.861), which was higher than that of PASP (AUC, 0.734; 95% CI, 0.675–0.793; p = 0.041), and LVEF (AUC, 0.699; 95% CI, 0.638–0.761; p = 0.008). After TAPSE/PASP was added to the baseline clinical model, the AUC increased from 0.781 (95% CI, 0.730–0.832) to 0.851 (95% CI, 0.809–0.893; DeLong test p = 0.002). The bootstrap-corrected AUC was 0.838 (95% bootstrap CI, 0.803–0.881), and the Hosmer–Lemeshow test indicated good calibration (χ2 = 6.48, p = 0.593). Conclusions: Preoperative TAPSE/PASP is an independent predictor of LCOS after CABG in patients with coronary artery disease and reduced ejection fraction. As part of routine preoperative echocardiographic assessment, this parameter may provide valuable incremental information for risk stratification in this high-risk population. Future prospective studies should further evaluate whether dynamic or exercise-derived RV-PA coupling can improve the prediction of functional outcomes and perioperative events beyond resting TAPSE/PASP in high-risk CABG patients.