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Objectives: Risk scoring models (RSMs) are commonly used for estimation of postoperative-mortality risk in patients undergoing cardiac surgery, but their prediction accuracy may vary in different populations and clinical situations. The prognostic accuracies of some RSMs have not yet been fully evaluated in the Australian population. In this retrospective observational study, our aims were to assess the performance of four contemporary RSMs, to identify the best RSMs for prediction of postoperative-mortality in the single-centre cohort, and to determine a statistical threshold for classification of patients with increased or "higher" mortality risk., Methods: The study population included patients who underwent cardiac surgery at Liverpool Hospital between January 2013 and December 2014. Demographic information was collected, and mortality risks were estimated with the ES2 (EuroSCORE II), STS (Society of Thoracic Surgeons Score), AS (AusSCORE total) and ASMR (AusSCORE multi-risk) RSMs. (Additive EuroSCORE) (AES) and LES (logistic EuroSCORE) were included for historical interest. Discrimination, the ability to stratify patients between mortality and no mortality outcomes, and calibration, the comparison of risk score estimated and observed outcome in the population, were evaluated for each RSM, to determine their predictive accuracy in the study population. Discrimination was assessed by the AUC (area under the receiver operating characteristic curve), and acceptable calibration by the p-value greater than 0.05 for the Hosmer-Lemeshow (H-L) test. The best AUCs in contempory models were compared using the DeLong test. For ES2 and STS risk scores, cut-off points, or thresholds, for patients at increased risk of mortality were derived using Youden's J-statistics, calculated from sensitivity and specificity of models in predicting mortality., Results: From a total study population of 898 patients, 738 had scores for all six RSMs. The three EuroSCORE risk models and Youden's J-statistics analysis included the total population. Of the models in contemporary use, ES2 had higher discrimination (AUC=0.850) in this population than ASMR (AUC=0.767, p=0.024) and AS (AUC=0.739) and non-significantly higher discrimination than STS (AUC=0.806, p=0.19). All contemporary models had acceptable calibration but the older LES (H-L p=0.024) did not. Estimated mortality was closest to observed mortality with the ES2 model. Both AES and LES over predicted mortality. The RSM with the highest discrimination in isolated coronary artery bypass graft surgery (CAGs) (AUC=0.847), isolated valves (AUC=0.830), and females (AUC=0.784) was the ES2 model. STS discrimination was highest in CAGs plus valve procedures (AUC 0.891), and males (STS AUC=0.891). Cut-off points for risk scores to define increased risk populations were 3.0% for ES2 and 1.7% for STS. Similar proportions of patients in each RSM (ES2-26% to STS-32%) were defined as higher risk by the model threshold score depending on type of procedure., Conclusion: Among RSMs in contemporary use, ES2 and STS showed the best discrimination and acceptable calibration. Caution is recommended in specific subgroups. Increased mortality risk score cut-off points could be identified for these two RSMs in this single-centre cohort., (Copyright © 2021. Published by Elsevier B.V.)

Background: Identifying predictors of bleeding in patients before coronary artery bypass grafting surgery is important, given the complications of bleeding and finite supply of blood. Patient response to aspirin is heterogeneous and can be evaluated using point-of-care platelet function tests. We postulated that patients who hyper-respond to aspirin given preoperatively, as identified by VerifyNow® Aspirin assay (Accumetrics, Inc., San Diego, CA, USA), are at increased risk of bleeding and transfusion., Methods: This prospective pilot study examined response to aspirin in patients undergoing coronary artery bypass grafting surgery (n = 61) from 2009 to 2013. Patients with aspirin reaction unit (ARU) values in the lower 50 th percentile as identified by VerifyNow® assays were defined as aspirin hyper-responders. The proportion of patients transfused and the median adjusted indexed drop in haemoglobin were compared between aspirin hyper-responders and non-hyper-responders. Logistic regression was performed to determine factors associated with increased risk of transfusion., Results: Seventy per cent (70%) of aspirin hyper-responders were transfused perioperatively compared with 39% of patients who did not hyper-respond, (OR 3.694, 95% CI 1.275-10.706, p = 0.014). VerifyNow® Aspirin hyper-responders had a greater median adjusted indexed drop in haemoglobin compared to non-hyper-responders (34.1 g/L versus 26.6 g/L respectively, p = 0.032). Multivariate analysis also showed VerifyNow® Aspirin hyper-response to be an independent predictor of transfusion (p = 0.016). Other variables such as age, gender, body mass index, renal insufficiency, and cross clamp and bypass times were not predictors of postoperative bleeding in this pilot cohort., Conclusions: VerifyNow® Aspirin is able to preoperatively identify aspirin hyper-responders at an increased risk of bleeding and subsequent transfusion in the context of coronary artery bypass graft surgery., (Copyright © 2019 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.)