Pre-operative anaemia-does it influence post-operative outcomes after isolated coronary artery bypass grafting?

Introduction: Preoperative anaemia is prevalent in a number of patients undergoing coronary artery bypass grafting. Studies provide conflicting results due to several reasons including variation in the threshold of haematocrit used to define anaemia. We aimed to assess the independent effect of preoperative anaemia on outcomes in patients undergoing off pump coronary artery bypass grafting (OPCAB). Methods: In this retrospective study, patients with a hemoglobin level less than 11g/dl (haematocrit <33%) were considered to have moderate-to-severe anaemia as per the recommendations of the World Health Organization. Association between haematocrit <33% and mortality as well as adverse post-operative outcomes was assessed. Multivariable logistic regression (MLR) was carried out to assess the independent effect of haematocrit<33% on 30-day mortality and other outcomes. Results: The study included 4957 consecutive patients undergoing isolated OPCAB surgery between 2015 and 2020. Out of 4957, 635 (12.8%) had haematocrit <33% and 4322 (81.2%) had haematocrit ≥33%. Patients with haematocrit < 33% had a 30-day mortality of 13 (2%) compared to 38 (0.9%) in patients without anaemia and had a greater requirement for blood transfusion (p<0.0001). It was also associated with an increased incidence of renal failure (p<0.0001), tracheostomy (p=.0.012) and risk of re-intubation (p=0.006). On multiple linear regression (MLR), haematocrit < 33% was not an independent predictor of 30-day mortality odds ratio (OR) 1.47, 95% confidence interval (CI) 0.745-2.917; p=0.26. It was however an important independent risk factor for blood transfusion (OR 1.80, 95% CI 1.29-2.50, p<0.001) and renal failure (OR 3.06, 95% CI 1.338-7.012, p=0.008). The receiver operating characteristic (ROC)-area under the curve (AUC) was 0.63 suggesting moderate discriminatory value of haematocrit < 33% for 30-day mortality. Conclusion: Haematocrit < 33% is an important risk factor for adverse outcomes following isolated, primary, elective OPCAB. Supplementary Information: The online version contains supplementary material available at 10.1007/s12055-024-01746-1.

Machine learning algorithms for population-specific risk score in coronary artery bypass grafting.

BACKGROUND: The aim of this study was to develop a new risk prediction score (NH Score) for patients undergoing coronary artery bypass grafting (CABG) specific to the Indian population and compare it to the Society of Thoracic Surgeon (STS) Score and the EuroSCORE II. METHOD: The baseline features of adult patients who underwent CABG between the years 2015 and 2021 (n = 6703) were taken and split into training data (2015-2020; n = 5561) and validation data (2020-2021; n = 1142). The CatBoost algorithm was trained to predict risk scores (NH score), and the performance was tested on the validation set by Precision-Recall Curve and F1 Score. Model calibration was measured by the Brier Score, Expected Calibration Error and Maximum Calibration Error. RESULTS: The NH score outperformed both the STS and EuroSCORE II for all outcomes. For mortality, the PR AUC for NH Score was (0.463 [95% confidence interval [CI], 0.28-0.64]) compared to 0.113 [95% CI, 0.04-0.22] for the STS score and 0.146 [95% CI, 0.06-0.31] for the EuroSCORE II (p ≪ 0.0001). With respect to morbidity NH Score was superior to the STS score (0.43 [95% CI, 0.33-0.50]) vs. (0.229 [95% CI, 0.18-0.3, p < 0.0001). The observed to the predicted ratio for NH score was superior to the STS Score and similar to EuroSCORE II. NH Score was also more accurate at predicting the risk of prolonged ventilation compared to the STS Score. CONCLUSION: NH score shows an excellent improvement over the performance of STS score and EuroSCORE II for modelling risk predictions for patients undergoing CABG in Indian population. It warrants further validation for larger datasets.

Effect of preoperative statins on respiratory complications after coronary artery bypass grafting.

OBJECTIVES: Limited data exist on the effect of preoperative statin therapy on postoperative respiratory complications. Machine learning algorithms (MLA) can process large, heterogenous data, and have immensely improved the ability for risk prediction. In this study, we sought to examine the role of preoperative statins on respiratory complications in patients undergoing coronary artery bypass grafting (CABG) using MLA. METHODS: The study population contained the data of patients who underwent CABG between the years 2015 and 2019 (n = 5638). Three hundred and thirty-seven independent variables were recorded and the data was randomly split with stratified sampling into training and testing data with 20% of the data (1113 records) reserved for model testing. Various models including linear models, Random forest, SVM, and XGboost were trained to predict the incidence of postoperative respiratory complications. Forty-seven important features were found to impact model prediction (p ≤ .05) using the global surrogate model method. A conventional multivariable linear regression model was then used to identify predictors of respiratory complications. RESULTS: One thousand three hundred sixty-two (24.5%) patients developed a respiratory complication in our series. The respiratory complication was seen in 561 (29.7%) of the patients who were not on statin compared to only 801 (21.8%) who were on a statin, p < .0001. The area under the curve for receiver operating characteristic curve using statins and respiratory complications was 0.706. Statins showed positive feature importance in all the MLA models. CONCLUSIONS: MLA showed that statins impacted the prediction of respiratory complications in all the models studied. The study confirmed that preoperative statins reduced the risk of respiratory complications by 21%.

Uptake and impact of vaccination against COVID-19 among healthcare workers-evidence from a multicentre study.

To assess vaccination among healthcare workers, 14837 healthcare workers across 20 different hospitals were prospectively surveyed. The overall uptake of the vaccine was 13335(90%). Infection rate in vaccinated HCW was 710(6.04%) and was significantly lower than unvaccinated HCW 148(9.9%), P <.001. Uptake of vaccination among healthcare workers in our study was high and provided significant protection compared to unimmunized healthcare workers.

Atrial fibrillation - Can HbA1c levels really predict the risk?

BACKGROUND: Diabetes is associated with higher mortality and worse post-operative outcomes in patients undergoing coronary artery bypass grafting and HbA1c levels have consistently been reported to be associated with adverse post-operative outcomes. However, the role of HbA1c still remains unclear with regards to the occurrence of atrial fibrillation. METHOD: Data for the patients undergoing off-pump coronary artery bypass grafting was analysed in a retrospective fashion. Patients were divided into-those with HbA1c < 6.5% and those with HbA1c ≥ 6.5% and the incidence of atrial fibrillation observed in these two groups. We also compared patient who developed atrial fibrillation in the post-operative period and compared them with those who did not. RESULTS: Of the 5259 patients included in the study HbA1c was <6.5 in 2808 (53.4%) patients and was ≥6.5 in 2451 (46.6%) patients; 623 (11.8%) patients in our study developed atrial fibrillation. Onset of atrial fibrillation in the post-operative period was seen most commonly 235 (38.3%) on between 24 and 48 h after the operation with more than half of them 338 (54.2%) occurring within the first 48 h. On multivariate analysis, HbA1c was not a risk factor for atrial fibrillation (odd's ratio 1.144, 95% confidence interval 0.967-1.354). Only increased age (odd's ratio 1.08; 95% confidence interval 1.069-1.091); EuroSCORE (odd's ratio 1.073; 95% confidence interval 1.048-1.099); history of recent MI (odd's ratio 0.768; 95% confidence interval 0.606-0.971) and peripheral vascular disease (odd's ratio 1.667; 95% confidence interval 1.091-2.517) were found to be independently associated with increased risk of atrial fibrillation in the post-operative period. CONCLUSIONS: After adjusting for confounders HbA1c levels do not independently predict risk of atrial fibrillation after off-pump coronary artery bypass grafting.

Comparison of European System for Cardiac Operative Risk Evaluation (EuroSCORE) and the Society of Thoracic Surgeons(STS) score for risk prediction in Indian patients undergoing coronary artery bypass grafting.

BACKGROUND: For risk stratifying patients undergoing coronary artery bypass graft (CABG), the Society of Thoracic Surgeons (STS) risk score and the European System for Cardiac Operative Risk Evaluation (EuroSCORE) are currently used. However, the superiority of one over the other in the context of Indian patients has not been assessed. The aim of this study was to compare these 2 scoring systems in Indian patients undergoing CABG. METHODOLOGY: This was a retrospective analysis of prospectively collected data between January 2015 and September 2020 of all patients undergoing CABG. Observed mortality in the cohort was compared with the predicted mortality using the STS and the EuroSCORE II. Sensitivity and specificity were calculated for both the scores. Receiver operating characteristic (ROC) curves were constructed for both the STS and the EuroSCORE II and area under the ROC curve (AUC) was calculated. RESULTS: A total of 4895 patients were included in the study. The overall observed mortality in the entire cohort was 74 (1.5%). The EuroSCORE II-predicted mortality was 1.9 ± 2.5 whereas the STS score-predicted mortality was 1.2 ± 1.8. The observed to predicted mortality ratio for EuroSCORE was 0.79 and 1.25 for the STS score. The discriminative ability for operative mortality of the STS score was 0.72 (0.71 to 0.74) and 0.713 for the EuroSCORE, suggesting satisfactory discriminatory power. There was no difference between the STS score and the EuroSCORE in terms of discriminatory power (p = 0.58) and a difference in the AUC being 0.01. The discriminatory power of the EuroSCORE and the STS score was best in the high-risk category. CONCLUSIONS: Both the EuroSCORE and the STS scores had satisfactory and similar discriminatory power. However, in the Indian population, while the EuroSCORE II overestimated mortality, the STS score underestimated it to a similar degree of error.

Preoperative Glycosylated Hemoglobin: A Risk Factor for Patients Undergoing Coronary Artery Bypass.

BACKGROUND: The prevalence of diabetes in the population of patients presenting with coronary artery disease continues to rise. The aim of this study was to assess whether high Glycosylated hemoglobin (HbA1c) was associated with adverse outcomes in patients undergoing elective coronary artery bypass grafting. METHODS: A retrospective observational study on prospectively collected data in 4,678 patients undergoing elective, isolated coronary artery bypass graft procedures in a single institution over a 4-year period was conducted. Patients were grouped into those with adequate preoperative control of hyperglycemia (HbA1c <6.5%) and those with suboptimal control (HbA1c ≥6.5%). Multivariable analysis using HbA1c as a binary independent variable was undertaken in the whole group. A subgroup analysis in diabetic patients and in nondiabetic patients was performed. The effect of HbA1c on outcomes at higher levels (HbA1c ≥8.0% and HbA1c ≥9.0%) was also assessed. RESULTS: A total of 4,678 patients (mean age, 58.8; male, 4,254) were included in the study. HbA1c was less than 6.5% in 2,476 (52.93%) patients and 6.5% or higher in 2,202 (47.07%) patients. On multivariate analysis, there was no difference in mortality rates between the groups (odds ratio, 1.36; 95% confidence interval [CI], 0.95 to 1.953; p = 0.08). Overall, an HbA1c of 6.5% or higher was an independent risk factor for respiratory complications (odds ratio, 1.05; 95% CI, 1.008 to 4.631; p = 0.01) and sternal dehiscence (odds ratio, 2.161; 95% CI, 1.008 to 4.63; p = 0.04). An association between HbA1c levels and adverse outcomes was not seen in nondiabetic patients. No additional adverse postoperative complications were seen with increasing HbA1c levels (HbA1c ≥8.0% and HbA1c ≥9.0%). CONCLUSIONS: An HbA1c level of 6.5% or higher in patients presenting for coronary artery bypass grafting was associated with a significant increase in the incidence of deep sternal wound infection and respiratory complications.