Development and Validation of a Novel Nomogram for Preoperative Prediction of In-Hospital Mortality After Coronary Artery Bypass Grafting Surgery in Heart Failure With Reduced Ejection Fraction

Abstract

Background and Aims: Patients with heart failure with reduced ejection fraction (HFrEF) are among the most challenging patients undergoing coronary artery bypass grafting surgery (CABG). Several surgical risk scores are commonly used to predict the risk in patients undergoing CABG. However, these risk scores do not specifically target HFrEF patients. We aim to develop and validate a new nomogram score to predict the risk of in-hospital mortality among HFrEF patients after CABG.Methods: The study retrospectively enrolled 489 patients who had HFrEF and underwent CABG. The outcome was postoperative in-hospital death. About 70% (n = 342) of the patients were randomly constituted a training cohort and the rest (n = 147) made a validation cohort. A multivariable logistic regression model was derived from the training cohort and presented as a nomogram to predict postoperative mortality in patients with HFrEF. The model performance was assessed in terms of discrimination and calibration. Besides, we compared the model with EuroSCORE-2 in terms of discrimination and calibration.Results: Postoperative death occurred in 26 (7.6%) out of 342 patients in the training cohort, and in 10 (6.8%) out of 147 patients in the validation cohort. Eight preoperative factors were associated with postoperative death, including age, critical state, recent myocardial infarction, stroke, left ventricular ejection fraction (LVEF) ≤35%, LV dilatation, increased serum creatinine, and combined surgery. The nomogram achieved good discrimination with C-indexes of 0.889 (95%CI, 0.839–0.938) and 0.899 (95%CI, 0.835–0.963) in predicting the risk of mortality after CABG in the training and validation cohorts, respectively, and showed well-fitted calibration curves in the patients whose predicted mortality probabilities were below 40%. Compared with EuroSCORE-2, the nomogram had significantly higher C-indexes in the training cohort (0.889 vs. 0.762, p = 0.005) as well as the validation cohort (0.899 vs. 0.816, p = 0.039). Besides, the nomogram had better calibration and reclassification than EuroSCORE-2 both in the training and validation cohort. The EuroSCORE-2 underestimated postoperative mortality risk, especially in high-risk patients.Conclusions: The nomogram provides an optimal preoperative estimation of mortality risk after CABG in patients with HFrEF and has the potential to facilitate identifying HFrEF patients at high risk of in-hospital mortality.

On- vs. Off-Pump CABG in Heart Failure Patients with Reduced Ejection Fraction (HFrEF): A Multicenter Analysis

“…Patients in the ONCAB group showed a higher incidence of hyperlipidemia than those in the OPCAB group. Despite this difference, we do not believe that this parameter played an important role in the peri-and postoperative outcomes, as it has not been described as such by other study groups [4]. Patients in the OPCAB group showed a significantly higher incidence of renal insufficiency and perivascular disease.…”

“…Both groups showed an ejection fraction < 40% and a median of three affected coronary vessels. Other groups have found a higher degree of preoperative kidney injury and higher NYHA classification to be risk factors for peri-and postoperative mortality in patients undergoing CABG [4,5,8]. When comparing preoperative risk scores, patients in the OPCAB group had a significantly higher STS score and EuroScore II than patients in the ONCAB group.…”

“…A significantly larger number of patients in the OPCAB group underwent urgent surgical intervention than in the ONCAB group; there was no difference regarding emergency procedures; patients in the ONCAB group underwent significantly more elective procedures than the OPCAB group. After analyzing the preoperative parameters, it is evident that patients in the OPCAB group underwent the procedures with a higher risk of mortality compared to patients in the ONCAB group [4][5][6]8].…”

“…Despite this evolution of techniques, using a cardiopulmonary bypass (CPB) is still the standard in CABG surgery (ONCAB) in Europe and the United States. It still has a significantly higher risk of morbidity and mortality in HFrEF patients compared to others [4]. Nonetheless, OPCAB as an alternative is a demanding procedure, and outcomes will vary depending on the patient's condition and the experience of the surgical team [5].…”

Risk stratification model integrating nutritional and inflammatory factors for predicting 1-year mortality after valvular heart surgery: a retrospective cohort study

“…Nomograms are a reliable tool to integrate and quantify potential risk factors by assigning a score to each factor 25 , and they have been actively studied in the field of cancer management 26 – 29 . In CABG patients with heart failure, a nomogram model for predicting in-hospital mortality had a better C -index than EuroSCORE II alone, highlighting the usefulness of a risk stratification nomogram tailored to the characteristics of the surgical patient group 30 , 31 . Several studies previously verified variables other than EuroSCORE II as being closely related to overall patient outcomes and postoperative mortality after cardiac surgery 4 , 22 , 32 , 33 , but these were not included in previous risk-scoring systems.…”