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Background: Surgery of the ascending aorta with or without arch is being performed in an increasingly elderly population with risks of coexisting coronary artery disease. Aim: To define specific groups requiring coronary artery bypass graft (CABG) and to analyse the influence of concomitant CABG on outcome. Design: Over a 10-year period in a single institution, 296 consecutive procedures on the ascending aorta with or without arch were carried out in 291 patients. CABG was required in 42 (14.2%) procedures. In 24 (57%) patients, CABG was planned preoperatively and in 18 (43%) patients, on a salvage basis. Results: In-hospital mortality for patients undergoing concomitant CABG was higher (21.4% v 11%, p<0.06). Adjusting for baseline and operative characteristics, this was attributable to operative priority, and was not a consequence of concomitant CABG (adjusted OR 0.30, 95% CI 1.1 to 8.31; p = 0.48). However, in-hospital mortality was significantly higher when CABG was performed as salvage rather than as a planned procedure (38.9% v 8.9%, p = 0.025), and this difference remained after adjusting for confounding variables (adjusted OR 16.2, 95% CI 1.03 to >200; p = 0.047). The 3-year survival was significantly lower with concomitant CABG (59% v 81.9%, p<0.001). Conclusions: In association with surgery of the ascending aorta with or without arch planned concomitant CABG did not entail any added operative risk. However, salvage CABG, which occurred almost exclusively in association with emergency cases, was associated with a higher early mortality. Patients needing concomitant CABG had worse survival at 3 years compared with those requiring isolated surgery of the ascending aorta with or without arch. [ABSTRACT FROM AUTHOR]

Background: Remote ischemic preconditioning (RIPC) induced by brief ischemia/reperfusion (I/R) cycles of remote organ (e.g. limb) is cardio-protective. The myocardial cellular changes during RIPC that are responsible for this phenomenon are not currently known. However, it is widely accepted that unlike classical ischemic preconditioning, RIPC does not induce ischemic stress in the myocardium. To address this issue we developed a novel RIPC mouse model and monitored myocardial changes in energy-rich phosphates.Methods: Treatment of animals and all procedures were in accordance with Home office guidance (Scientific Procedures) Act of 1986. Male C57/Bl6 mice were anesthetized by an intra-peritoneal injection of Tribromoethanol. A suitably designed cuff was placed around the hind limb and inflated at 200mmHg to prevent blood flow as confirmed by Laser Doppler Flowmetry. RIPC was induced by 4 cycles of 5min of limb ischemia followed by 5min of reperfusion. Hearts were extracted and used for either measurement of metabolites or perfused in the Langendorff mode. Injury and recovery of function were obtained for RIPC and sham operated mice. Myocardial metabolites (e.g. adenine and guanine nucleotides and by-products) from excised hearts following RIPC were extracted and measured using HPLC.Results: RIPC significantly reduces infarct size (34% vs. 59%; P<0.05), total creatine kinase release and end diastolic tension following I/R. RIPC was associated with significant ischemic stress as shown by a fall in ATP/AMP (1.324± 0.124 vs. 0.965± 0.036 P<0.05), ATP/ADP (0.917 ± 0.03 vs. 0.805± 0.025 P<0.05 ), GTP/GMP (2.71± 0.162 vs. 2.019± 0.103 P<0.005) and GTP/GDP (0.87 ± 0.017 vs. 0.749± 0.021 P<0.005 ). There was also a significant increase in myocardial adenosine (0.21± 0.032 vs. 0.127± 0.01 nmol/mg wet weight, P<0.05).Conclusions: RIPC is associated with myocardial ischemic stress. This effect is likely to contribute to RIPC-induced protection against sustained ischemic insult. [ABSTRACT FROM PUBLISHER]

Introduction The National Training Survey (NTS) is conducted annually by the General Medical Council (GMC) to monitor and report on the quality of postgraduate medical education and training. The coronavirus disease 2019 (COVID-19) pandemic had a significant impact on training in cardiothoracic surgery due to the unprecedented restructuring of surgical activity across the UK. We aim to evaluate how the job satisfaction of cardiothoracic surgery trainees was impacted by COVID-19 using the National Training Survey. Methods The National Training Survey in cardiothoracic surgery from 2017 to 2024 was obtained from the General Medical Council website. Job satisfaction for trainees was evaluated using 17 indicators: Adequate Experience, Clinical Supervision, Clinical Supervision Out of Hours, Educational Governance, Educational Supervision, Feedback, Handover, Induction, Local Teaching, Overall Satisfaction, Regional Teaching, Reporting Systems, Rota Design, Study Leave, Supportive Environment, Teamwork and Workload. The pre-pandemic score for each indicator was an average of 2017, 2018 and 2019, while the post-pandemic score was an average of 2022, 2023 and 2024. The overall job satisfaction per year, combining all indicators, was also analysed. Results Thirty-eight cardiothoracic centres were included in this study. There was a reduction in trainees' job satisfaction from pre- to post-pandemic surveys when comparing all 17 indicators together (scored out of 100) (73.87 versus 70.97, p<0.001). There were six out of 17 (35.29%) indicators that demonstrated a significant decrease in job satisfaction amongst trainees: Regional Teaching (70.53 versus 54.53, p<0.001), Adequate Experience (78.65 versus 72.34, p=0.003), Local Teaching (68.26 versus 62.92, p=0.037), Educational Governance (73.78 versus 70.36, p=0.033), Clinical Supervision Out of Hours (91.16 versus 87.95, p=0.005) and Clinical Supervision (91.98 versus 88.92, p=0.014). Conclusion Trainees' job satisfaction significantly decreased after the COVID-19 pandemic. Although the most recent survey suggests job satisfaction amongst trainees may be recovering, further work needs to be done to ensure training standards return to pre-pandemic levels., Competing Interests: Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, O'Hanlon et al.)

Background: Ensemble tree-based models such as Xgboost are highly prognostic in cardiovascular medicine, as measured by the Clinical Effectiveness Metric (CEM). However, their ability to handle correlated data, such as hospital-level effects, is limited., Objectives: The aim of this work is to develop a binary-outcome mixed-effects Xgboost (BME) model that integrates random effects at the hospital level. To ascertain how well the model handles correlated data in cardiovascular outcomes, we aim to assess its performance and compare it to fixed-effects Xgboost and traditional logistic regression models., Methods: A total of 227,087 patients over 17 years of age, undergoing cardiac surgery from 42 UK hospitals between 1 January 2012 and 31 March 2019, were included. The dataset was split into two cohorts: training/validation (n = 157,196; 2012-2016) and holdout (n = 69,891; 2017-2019). The outcome variable was 30-day mortality with hospitals considered as the clustering variable. The logistic regression, mixed-effects logistic regression, Xgboost and binary-outcome mixed-effects Xgboost (BME) were fitted to both standardized and unstandardized datasets across a range of sample sizes and the estimated prediction power metrics were compared to identify the best approach., Results: The exploratory study found high variability in hospital-related mortality across datasets, which supported the adoption of the mixed-effects models. Unstandardized Xgboost BME demonstrated marked improvements in prediction power over the Xgboost model at small sample size ranges, but performance differences decreased as dataset sizes increased. Generalized linear models (glms) and generalized linear mixed-effects models (glmers) followed similar results, with the Xgboost models also excelling at greater sample sizes., Conclusions: These findings suggest that integrating mixed effects into machine learning models can enhance their performance on datasets where the sample size is small.

Background/Objectives : Grafting of LIMA to LAD has long been considered the gold-standard conduit choice for patients undergoing CABG. Despite this, the LSV remains the most used conduit by volume and some patients may not receive even a single arterial conduit. However, the outcomes in this group are not frequently explored. This study, therefore, compares in-hospital outcomes of patients who underwent CABG without any arterial conduits to those who received at least one arterial conduit. Methods : Retrospective propensity-matched database analysis of consecutive patients undergoing CABG in the UK between 1996 and 2019 using data from the National Adult Cardiac Surgery Audit. Results : 335,144 patients underwent CABG, with 6% receiving venous conduits only; matched outcomes are reported for 39,812 patients. In both unmatched and matched groups, we found a significant increase in mortality with the use of veins only (matched mortality 5.3% vs. 3.8%, p < 0.001) with estimated treatment effect for mortality OR 1.43, p < 0.001 (95% CI: 1.31-1.57). We also identified greater rates of post-operative dialysis, IABP insertion, and length of hospital stay in this group. Conclusions : We identified a significant increase in in-hospital mortality with the use of veins only compared to using at least one arterial graft to the LAD. While a single arterial graft should be prioritised wherever possible, venous revascularisation retains a critical role for specific patients. We must, therefore, continue to conduct research addressing the mechanisms underlying and propagating vein graft disease in order better to optimise outcomes for this niche patient group after CABG.

Coronary artery disease (CAD) is a major health issue. This study focused on pericardial macrophages and small extracellular vesicles (sEVs) in CAD. The macrophages in CAD patients showed reduced expression of protective markers and unchanged levels of proinflammatory receptors. Similar changes were observed in buffy-coat-derived macrophages when stimulated with CAD pericardial fluid-derived sEVs. The sEV contained miRNA-6516-5p, which inhibited CD36 and affected macrophage lipid uptake. These findings indicate that sEV-mediated miRNA actions contribute to the decrease in protective pericardial macrophages in CAD., Competing Interests: This study was supported by the British Heart Foundation (BHF) Programme Grant-RG/15/5/31446 and Personal Chair Awards-CH/15/1/31199 (to Dr Emanueli); BHF Transitional Fellowship (Imperial College London BHF Centre of Research Excellence-RE/18/4/34215) and BHF Project Grant (BHF- PG/23/11336) (both to Dr Ben-Aicha); UKRI Postdoctoral Fellowship-EP/X023729/1 (to Dr Martino); a grant from The Leducq Foundation (to Dr Sattler); PLEC2021–007664-Unión Europea NextGeneration EU/PRTR, grant PID2021-128891OB-I00, and grant M-ERA-NET-3 / PCI2023-143431 - European Funds (all to Dr Vilahur). This study was also funded by MCIN/AEI/10.13039/501100011033 and Fondo Europeo de Desarrollo Regional, A way of making Europe. This manuscript was also supported by the UK National Institute of Heart Research (NIHR) for funding this research. The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2024 The Authors.)

Background: The Society of Thoracic Surgeons and European System for Cardiac Operative Risk Evaluation (EuroSCORE) II risk scores are the most commonly used risk prediction models for in-hospital mortality after adult cardiac surgery. However, they are prone to miscalibration over time and poor generalization across data sets; thus, their use remains controversial. Despite increased interest, a gap in understanding the effect of data set drift on the performance of machine learning (ML) over time remains a barrier to its wider use in clinical practice. Data set drift occurs when an ML system underperforms because of a mismatch between the data it was developed from and the data on which it is deployed., Objective: In this study, we analyzed the extent of performance drift using models built on a large UK cardiac surgery database. The objectives were to (1) rank and assess the extent of performance drift in cardiac surgery risk ML models over time and (2) investigate any potential influence of data set drift and variable importance drift on performance drift., Methods: We conducted a retrospective analysis of prospectively, routinely gathered data on adult patients undergoing cardiac surgery in the United Kingdom between 2012 and 2019. We temporally split the data 70:30 into a training and validation set and a holdout set. Five novel ML mortality prediction models were developed and assessed, along with EuroSCORE II, for relationships between and within variable importance drift, performance drift, and actual data set drift. Performance was assessed using a consensus metric., Results: A total of 227,087 adults underwent cardiac surgery during the study period, with a mortality rate of 2.76% (n=6258). There was strong evidence of a decrease in overall performance across all models (P<.0001). Extreme gradient boosting (clinical effectiveness metric [CEM] 0.728, 95% CI 0.728-0.729) and random forest (CEM 0.727, 95% CI 0.727-0.728) were the overall best-performing models, both temporally and nontemporally. EuroSCORE II performed the worst across all comparisons. Sharp changes in variable importance and data set drift from October to December 2017, from June to July 2018, and from December 2018 to February 2019 mirrored the effects of performance decrease across models., Conclusions: All models show a decrease in at least 3 of the 5 individual metrics. CEM and variable importance drift detection demonstrate the limitation of logistic regression methods used for cardiac surgery risk prediction and the effects of data set drift. Future work will be required to determine the interplay between ML models and whether ensemble models could improve on their respective performance advantages., (© Tim Dong, Shubhra Sinha, Ben Zhai, Daniel Fudulu, Jeremy Chan, Pradeep Narayan, Andy Judge, Massimo Caputo, Arnaldo Dimagli, Umberto Benedetto, Gianni D Angelini. Originally published in JMIRx Med (https://med.jmirx.org).)

Background: The ProMPT-2 trial (Propofol for Myocardial Protection Trial #2) aims to compare the safety and efficacy of low- and high-dose propofol supplementation of the cardioplegia solution during adult cardiac surgery versus sham supplementation. This update presents the statistical analysis plan, detailing how the trial data will be analysed and presented. Outlined analyses are in line with the Consolidated Standards of Reporting Trials and the statistical analysis plan has been written prior to database lock and the final analysis of trial data to avoid reporting bias (following recommendations from the International Conference on Harmonisation of Good Clinical Practice)., Methods/design: ProMPT-2 is a multi-centre, blinded, parallel three-group randomised controlled trial aiming to recruit 240 participants from UK cardiac surgery centres to either sham cardioplegia supplementation, low dose (6 µg/ml) or high dose (12 µg/ml) propofol cardioplegia supplementation. The primary outcome is cardiac-specific troponin T levels (a biomarker of cardiac injury) measured during the first 48 h following surgery. The statistical analysis plan describes the planned analyses of the trial primary and secondary outcomes in detail, including approaches to deal with missing data, multiple testing, violation of model assumptions, withdrawals from the trial, non-adherence with the treatment and other protocol deviations. It also outlines the planned sensitivity analyses and exploratory analyses to be performed., Discussion: This manuscript prospectively describes, prior to the completion of data collection and database lock, the analyses to be undertaken for the ProMPT-2 trial to reduce risk of reporting and data-driven analyses., Trial Registration: ISRCTN ISRCTN15255199. Registered on 26 March 2019., (© 2024. The Author(s).)

Introduction: On-pump coronary artery bypass (ONCABG) grafting in patients with a pre-existing poor renal reserve is known to carry significant morbidity and mortality. There is limited controversial evidence on the benefit of off-pump coronary artery bypass (OPCABG) grafting in these high-risk groups of patients. We compared early clinical outcomes in propensity-matched cohorts of patients with non-dialysis-dependent pre-operative severe renal impairment undergoing OPCABG vs. ONCABG, captured in a large national registry dataset., Methods: All data for patients with a pre-operative creatinine clearance of less than 50 mL/min who underwent elective or urgent isolated OPCABG or ONCABG from 1996 to 2019 were extracted from the UK National Adult Cardiac Surgery Audit (NACSA) database. Propensity score matching was performed using 1:1 nearest neighbor matching without replacement using several baseline characteristics. We investigated the effect of ONCABG vs. OPCABG in the matched cohort using cluster-robust standard error regression., Results: We identified 8,628 patients with severe renal impairment undergoing isolated CABG, of whom 1,142 (13.23%) underwent OPCABG during the study period. We compared 1,141 propensity-matched pairs of patients undergoing OPCABG vs. ONCABG. The median age of the matched population was 78 years in both groups, with no significant imbalance post-matching in the rest of the variables. There was no difference between OPCABG and ONCABG in in-hospital mortality rates, post-operative dialysis, and stroke rates. However, the return to theatre for bleeding or tamponade was higher in ONCABG vs. OPCABG ( P  > 0.02); however, OPCABG reduced the total length of stay in the hospital by 1 day ( P  = 0.008). After double adjustment in the matched population using cluster-robust standard regression, ONCABG did not increase mortality compared to OPCABG (OR, 1.05, P  = 0.78), postoperative stroke (OR, 1.7, P  = 0.12), and dialysis (OR, 0.7, P  = 0.09); however, ONCABG was associated with an increased risk of bleeding (OR, 1.53, P  = 0.03)., Discussion: In this propensity analysis of a large national registry dataset, we found no difference in early mortality and stroke in patients with pre-operative severe renal impairment undergoing OPCABG or ONCABG surgery; however, ONCABG was associated with an increased risk of return to theatre for bleeding and an increased length of hospital stay., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers at the time of submission. This had no impact on the peer review process or the final decision., (© 2024 Fudulu, Argyriou, Kota, Chan, Vohra, Caputo, Zakkar and Angelini.)

Cerebrovascular accident is the most ominous complication observed after cardiac surgery, carrying an increased risk of morbidity and mortality. Analysis of the problem shows its multidimensional nature. In this study, we aimed to identify major determinants among classic variables, either demographic, clinical or type of surgical procedure, based on the analysis of a large dataset of 580,117 patients from the UK National Adult Cardiac Surgical Audit (NACSA). For this purpose, univariate and multivariate logistic regression models were utilized to determine associations between predictors and dependent variable (Stroke after cardiac surgery). Odds ratios (ORs) and 95% confidence intervals (CIs) were constructed for each independent variable. Statistical analysis allows us to confirm with greater certainty the predictive value of some variables such as age, gender, diabetes mellitus (diabetes treated with insulin OR = 1.37, 95%CI = 1.23-1.53), and systemic arterial hypertension (OR = 1.11, 95%CI = 1.05-1.16);, to emphasize the role of preoperative atrial fibrillation (OR = 1.10, 95%CI = 1.03-1.16) extracardiac arteriopathy (OR = 1.70, 95%CI = 1.58-1.82), and previous cerebral vascular accident (OR 1.71, 95%CI = 1.6-1.9), and to reappraise others like smoking status (crude OR = 1.00, 95%CI = 0.93-1.07 for current smokers) or BMI (OR = 0.98, 95%CI = 0.97-0.98). This could allow for better preoperative risk stratification. In addition, identifying those surgical procedures (for example thoracic aortic surgery associated with a crude OR of 3.72 and 95%CI = 3.53-3.93) burdened by a high risk of neurological complications may help broaden the field of preventive and protective techniques.

Background: Redo sternotomy aortic root surgery is technically demanding, and the evidence on outcomes is mostly from retrospective, small sample, single-centre studies. We report the trend, early clinical results and outcome predictors of redo aortic root replacement over 20 years in the United Kingdom., Methods: We retrospectively analysed collected data from the UK National Adult Cardiac Surgery Audit (NACSA) on all redo sternotomy aortic root replacements performed between 30th January 1998 and 19th March 2019. We analysed trends in the volume of operations, characteristics of hospital survivors vs. non-survivors, and predictors of in-hospital outcomes., Results: During the study period, 1,107 redo sternotomy aortic root replacements were performed (median age 59, 26% of patients were females). Eighty-four per cent of cases ( N  = 931) underwent a composite root replacement, 11% ( N  = 119) had homograft root replacement and valve-sparing root replacement was performed in 5.1% ( N  = 57) of cases. There was a steady increase in the volume of redo sternotomy root replacements beyond 2006, from an annual volume of 22 procedures in 2006 to 106 procedures in 2017. Hospital mortality was 17% ( n  = 192), postoperative stroke or TIA occurred in 5.2% ( n  = 58), and postoperative dialysis was required in 11% ( n  = 109) of patients. Return to the theatre for bleeding/tamponade was required in 9% ( n  = 102) and median in-hospital stay was 9 days. Age >59 (OR: 2.99, CI: 1.92-4.65, P  < 0.001), recent myocardial infarction (OR: 6.42, CI: 2.24-18.41, P  = 0.001) were associated with increased in-hospital mortality. Emergency surgery (OR: 3.95, 2.27-6.86, P  < 0.001), surgery for endocarditis (OR: 2.05, CI: 1.26-3.33, P  = 0.001), salvage coronary artery bypass grafting (OR: 2.20, CI: 1.37-3.54, P  < 0.001), arch surgery (OR: 2.47, CI: 1.30-3.61, P  = 0.018) and aortic cross-clamp longer than 169 min (OR: 2.17, CI: 1.00-1.01, P  = 0.003) were associated with increased risk of mortality. We found no effect of the centre or surgeon volume on mortality ( P  > 0.05)., Conclusions: Redo sternotomy aortic root replacement still carries significant morbidity and mortality and is sporadically performed across surgeons and centres in the UK., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (© 2024 Fudulu, Dong, Kota, Sinha, Chan, Rajakaruna, Dimagli, Angelini and Ahmed.)

Background: Osteopontin has been implicated in vascular calcification formation and vein graft intimal hyperplasia, and its expression can be triggered by pro-inflammatory activation of cells. The role of osteopontin and the temporal formation of microcalcification in vein grafts is poorly understood with a lack of understanding of the interaction between haemodynamic changes and the activation of osteopontin., Methods: We used a porcine model of vein interposition grafts, and human long saphenous veins exposed to ex vivo perfusion, to study the activation of osteopontin using polymerase chain reaction, immunostaining, and 18 F-sodium fluoride autoradiography., Results: The porcine model showed that osteopontin is active in grafts within 1 week following surgery and demonstrated the presence of microcalcification. A brief pretreatment of long saphenous veins with dexamethasone can suppress osteopontin activation. Prolonged culture of veins after exposure to acute arterial haemodynamics resulted in the formation of microcalcification but this was suppressed by pretreatment with dexamethasone. 18 F-sodium fluoride uptake was significantly increased as early as 1 week in both models, and the pretreatment of long saphenous veins with dexamethasone was able to abolish its uptake., Conclusions: Osteopontin is activated in vein grafts and is associated with microcalcification formation. A brief pretreatment of veins ex vivo with dexamethasone can suppress its activation and associated microcalcification.

Background: Although electronic health records (EHR) provide useful insights into disease patterns and patient treatment optimisation, their reliance on unstructured data presents a difficulty. Echocardiography reports, which provide extensive pathology information for cardiovascular patients, are particularly challenging to extract and analyse, because of their narrative structure. Although natural language processing (NLP) has been utilised successfully in a variety of medical fields, it is not commonly used in echocardiography analysis., Objectives: To develop an NLP-based approach for extracting and categorising data from echocardiography reports by accurately converting continuous (e.g., LVOT VTI, AV VTI and TR Vmax) and discrete (e.g., regurgitation severity) outcomes in a semi-structured narrative format into a structured and categorised format, allowing for future research or clinical use., Methods: 135,062 Trans-Thoracic Echocardiogram (TTE) reports were derived from 146967 baseline echocardiogram reports and split into three cohorts: Training and Validation (n = 1075), Test Dataset (n = 98) and Application Dataset (n = 133,889). The NLP system was developed and was iteratively refined using medical expert knowledge. The system was used to curate a moderate-fidelity database from extractions of 133,889 reports. A hold-out validation set of 98 reports was blindly annotated and extracted by two clinicians for comparison with the NLP extraction. Agreement, discrimination, accuracy and calibration of outcome measure extractions were evaluated., Results: Continuous outcomes including LVOT VTI, AV VTI and TR Vmax exhibited perfect inter-rater reliability using intra-class correlation scores (ICC = 1.00, p < 0.05) alongside high R 2 values, demonstrating an ideal alignment between the NLP system and clinicians. A good level (ICC = 0.75-0.9, p < 0.05) of inter-rater reliability was observed for outcomes such as LVOT Diam, Lateral MAPSE, Peak E Velocity, Lateral E' Velocity, PV Vmax, Sinuses of Valsalva and Ascending Aorta diameters. Furthermore, the accuracy rate for discrete outcome measures was 91.38% in the confusion matrix analysis, indicating effective performance., Conclusions: The NLP-based technique yielded good results when it came to extracting and categorising data from echocardiography reports. The system demonstrated a high degree of agreement and concordance with clinician extractions. This study contributes to the effective use of semi-structured data by providing a useful tool for converting semi-structured text to a structured echo report that can be used for data management. Additional validation and implementation in healthcare settings can improve data availability and support research and clinical decision-making.

Background: Mortality after reoperative aortic valve surgery continues to decline but remains high compared with primary isolated replacement. We sought to examine temporal trends, morbidity, and mortality among patients undergoing isolated first-time reoperative aortic valve surgery., Methods: The study included all patients undergoing reoperative aortic valve surgery in the United Kingdom between January 2007 and March 2019. Patients undergoing isolated reoperative aortic valve replacement (AVR) were compared with a propensity matched cohort of patients undergoing isolated primary AVR. Outcomes measured included inhospital mortality, neurologic dysfunction, postoperative dialysis, deep sternal wound infections, and hospital length of stay., Results: During the study period, 40,858 primary isolated AVRs and 3015 first-time isolated reoperative AVRs were carried out in the United Kingdom. In the propensity matched reoperative group, median age of participants was 69.8 years (60.8-76.2) with median duration between the initial surgery and the reoperation being 7.69 years. Overall mortality was 3.1% (94) for reoperative AVR compared with 1.9% (56) for primary AVR. Mortality of both primary and reoperative AVR declined during the study period. Reoperation, age, New York Heart Association class, and chronic kidney disease were independently associated with early mortality., Conclusions: Reoperative isolated AVR can be performed with acceptable inhospital mortality and provides a benchmark against which alternative strategies should be compared., (Copyright © 2023 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: The introduction of new clinical risk scores (e.g. European System for Cardiac Operative Risk Evaluation (EuroSCORE) II) superseding original scores (e.g. EuroSCORE I) with different variable sets typically result in disparate datasets due to high levels of missingness for new score variables prior to time of adoption. Little is known about the use of ensemble learning to incorporate disparate data from legacy scores. We tested the hypothesised that Homogenenous and Heterogeneous Machine Learning (ML) ensembles will have better performance than ensembles of Dynamic Model Averaging (DMA) for combining knowledge from EuroSCORE I legacy data with EuroSCORE II data to predict cardiac surgery risk., Methods: Using the National Adult Cardiac Surgery Audit dataset, we trained 12 different base learner models, based on two different variable sets from either EuroSCORE I (LogES) or EuroScore II (ES II), partitioned by the time of score adoption (1996-2016 or 2012-2016) and evaluated on holdout set (2017-2019). These base learner models were ensembled using nine different combinations of six ML algorithms to produce homogeneous or heterogeneous ensembles. Performance was assessed using a consensus metric., Results: Xgboost homogenous ensemble (HE) was the highest performing model (clinical effectiveness metric (CEM) 0.725) with area under the curve (AUC) (0.8327; 95% confidence interval (CI) 0.8323-0.8329) followed by Random Forest HE (CEM 0.723; AUC 0.8325; 95%CI 0.8320-0.8326). Across different heterogenous ensembles, significantly better performance was obtained by combining siloed datasets across time (CEM 0.720) than building ensembles of either 1996-2011 ( t -test adjusted, p  = 1.67×10 -6 ) or 2012-2019 ( t -test adjusted, p  = 1.35×10 -193 ) datasets alone., Conclusions: Both homogenous and heterogenous ML ensembles performed significantly better than DMA ensemble of Bayesian Update models. Time-dependent ensemble combination of variables, having differing qualities according to time of score adoption, enabled previously siloed data to be combined, leading to increased power, clinical interpretability of variables and usage of data., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2023.)

Objectives: Using a large national database, we sought to describe outcome trends in mitral valve surgery between 2000 and 2019., Methods: The study cohort was split into mitral valve repair (MVr) or replacement, including all patients regardless of concomitant procedures. Patients were grouped by four-year admission periods into groups (A to E). The primary outcome was in hospital mortality and secondary outcomes were return to theatre, postoperative stroke and postoperative length of stay. We investigated trends over time in patient demographics, comorbidities, intraoperative characteristics and postoperative outcomes. We used a multivariable binary logistic regression model to assess the relationship between mortality and time. Cohorts were further stratified by sex and aetiology., Results: Of the 63 000 patients in the study cohort, 31 644 had an MVr and 31 356 had a replacement. Significant demographic shifts were observed. Aetiology has shifted towards degenerative disease; endocarditis rates in MVr dropped initially but are now rising (period A = 6%, period C = 4%, period E = 6%; P < 0.001). The burden of comorbidities has increased over time. In the latest time period, women had lower repair rates (49% vs 67%, P < 0.001) and higher mortality rates when undergoing repair (3% vs 2%, P = 0.001) than men. Unadjusted postoperative mortality dropped in MVr (5% vs 2%, P < 0.001) and replacement (9% vs 7%, P = 0.015). Secondary outcomes have improved. Time period was an independent predictor for reduced mortality in both repair (odds ratio: 0.41, 95% confidence interval: 0.28-0.61, P < 0.001) and replacement (odds ratio: 0.50, 95% confidence interval: 0.41-0.61, P < 0.001)., Conclusions: In-hospital mortality has dropped significantly over time for mitral valve surgery in the UK. MVr has become the more common procedure. Sex-based discrepancies in repair rates and mortality require further investigation. Endocarditis rates in MVS are rising., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.)

Objectives: To perform a systematic comparison of in-hospital mortality risk prediction post-cardiac surgery, between the predominant scoring system-European System for Cardiac Operative Risk Evaluation (EuroSCORE) II, logistic regression (LR) retrained on the same variables and alternative machine learning techniques (ML)-random forest (RF), neural networks (NN), XGBoost and weighted support vector machine., Methods: Retrospective analyses of prospectively routinely collected data on adult patients undergoing cardiac surgery in the UK from January 2012 to March 2019. Data were temporally split 70:30 into training and validation subsets. Mortality prediction models were created using the 18 variables of EuroSCORE II. Comparisons of discrimination, calibration and clinical utility were then conducted. Changes in model performance, variable-importance over time and hospital/operation-based model performance were also reviewed., Results: Of the 227 087 adults who underwent cardiac surgery during the study period, there were 6258 deaths (2.76%). In the testing cohort, there was an improvement in discrimination [XGBoost (95% confidence interval (CI) area under the receiver operator curve (AUC), 0.834-0.834, F1 score, 0.276-0.280) and RF (95% CI AUC, 0.833-0.834, F1, 0.277-0.281)] compared with EuroSCORE II (95% CI AUC, 0.817-0.818, F1, 0.243-0.245). There was no significant improvement in calibration with ML and retrained-LR compared to EuroSCORE II. However, EuroSCORE II overestimated risk across all deciles of risk and over time. The calibration drift was lowest in NN, XGBoost and RF compared with EuroSCORE II. Decision curve analysis showed XGBoost and RF to have greater net benefit than EuroSCORE II., Conclusions: ML techniques showed some statistical improvements over retrained-LR and EuroSCORE II. The clinical impact of this improvement is modest at present. However the incorporation of additional risk factors in future studies may improve upon these findings and warrants further study., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.)

Introduction: Postoperative Atrial Fibrillation (POAF) is a common complication of cardiac surgery, associated with increased mortality, stroke risk, cardiac failure and prolonged hospital stay. Our study aimed to assess the patterns of release of systemic cytokines in patients with and without POAF., Methods: A post-hoc analysis of the Remote Ischemic Preconditioning (RIPC) trial, including 121 patients (93 males and 28 females, mean age of 68 years old) who underwent isolated coronary artery bypass grafting (CABG) and aortic valve replacement (AVR). Mixed-effect models were used to analyze patterns of release of cytokines in POAF and non-AF patients. A logistic regression model was used to assess the effect of peak cytokine concentration (6 h after the aortic cross-clamp release) alongside other clinical predictors on the development of POAF., Results: We found no significant difference in the patterns of release of IL-6 ( p  = 0.52), IL-10 ( p  = 0.39), IL-8 ( p  = 0.20) and TNF-α ( p  = 0.55) between POAF and non-AF patients. Also, we found no significant predictive value in peak concentrations of IL-6 ( p  = 0.2), IL-8 ( p  = >0.9), IL-10 ( p  = >0.9) and Tumour Necrosis Factor Alpha (TNF-α)( p  = 0.6), however age and aortic cross-clamp time were significant predictors of POAF development across all models., Conclusions: Our study suggests no significant association exists between cytokine release patterns and the development of POAF. Age and Aortic Cross-clamp time were found to be significant predictors of POAF., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Kota, Gemelli, Dimagli, Suleiman, Moscarelli, Dong, Angelini and Fudulu.)

Introduction: Brain injury is common following open heart valve surgery. Carbon dioxide insufflation (CDI) has been proposed to reduce the incidence of brain injury by reducing the number of air microemboli entering the bloodstream in surgery. The CO2 Study will evaluate the efficacy and safety of CDI in patients undergoing planned left-sided open heart valve surgery., Methods and Analysis: The CO2 Study is a multicentre, blinded, placebo-controlled, randomised controlled trial. Seven-hundred and four patients aged 50 years and over undergoing planned left-sided heart valve surgery will be recruited to the study, from at least eight UK National Health Service hospitals, and randomised in a 1:1 ratio to receive CDI or medical air insufflation (placebo) in addition to standard de-airing. Insufflation will be delivered at a flow rate of 5 L/min from before the initiation of cardiopulmonary bypass until 10 min after cardiopulmonary bypass weaning. Participants will be followed up until 3 months post-surgery. The primary outcome is acute ischaemic brain injury within 10 days post-surgery based on new brain lesions identified with diffusion-weighted MRI or clinical evidence of permanent brain injury according to the current definition of stroke., Ethics and Dissemination: The study was approved by the East Midlands-Nottingham 2 Research Ethics Committee in June 2020 and the Medicines and Healthcare products Regulatory Agency in May 2020. All participants will provide written informed consent prior to undertaking any study assessments. Consent will be obtained by the principal investigator or a delegated member of the research team who has been trained in the study and undergone Good Clinical Practice training. Results will be disseminated through peer-reviewed publications and presentations at national and international meetings. Study participants will be informed of results through study notifications and patient organisations., Trial Registration Number: ISRCTN30671536., Competing Interests: Competing interests: CR, GDA and BG received support from the National Institute for Health and Care Research for the project associated with this manuscript, which was paid to the University of Bristol. RT, MP, LC, ML and SK received support from the National Institute for Health and Care Research for the project associated with this manuscript, which contributed to their salary. PP, NV and RS received support from the National Institute for Health and Care Research for the project associated with this manuscript, which was paid to the University of Oxford. EA received support from the National Institute for Health and Care Research for the project associated with this manuscript, which was paid to the RS reports ad hoc payments for providing expert testimony for the Parliamentary & Health Service Ombudsman. RS is the director and shareholder of Oxford Heart Surgery, chairs the Intercollegiate Speciality Board on Cardiothoracic Surgery, and is a member of the Special Advisory Committee in Cardiothoracic Surgery for the Royal Surgery Colleges. RS is an honorary secretary of the Society for Cardiothoracic Surgery in Great Britain and Ireland. No other conflicts were reported., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Intermittent cold blood cardioplegia is commonly used in children, whereas intermittent warm blood cardioplegia is widely used in adults. We aimed to compare clinical and biochemical outcomes with these 2 methods., Methods: A single-centre, randomized controlled trial was conducted to compare the effectiveness of warm (≥34°C) versus cold (4-6°C) antegrade cardioplegia in children. The primary outcome was cardiac troponin T over the 1st 48 postoperative hours. Intensive care teams were blinded to group allocation. Outcomes were compared by intention-to-treat using linear mixed-effects, logistic or Cox regression., Results: 97 participants with median age of 1.2 years were randomized (49 to warm, 48 to cold cardioplegia); 59 participants (61%) had a risk-adjusted congenital heart surgery score of 3 or above. There were no deaths and 92 participants were followed to 3-months. Troponin release was similar in both groups [geometric mean ratio 1.07; 95% confidence interval (CI) 0.79-1.44; P = 0.66], as were other cardiac function measures (echocardiography, arterial and venous blood gases, vasoactive-inotrope score, arrhythmias). Intensive care stay was on average 14.6 h longer in the warm group (hazard ratio 0.52; 95% CI 0.34-0.79; P = 0.003), with a trend towards longer overall hospital stays (hazard ratio 0.66; 95% CI 0.43-1.02; P = 0.060) compared with the cold group. This could be related to more unplanned reoperations on bypass in the warm group compared to cold group (3 vs 1)., Conclusions: Warm blood cardioplegia is a safe and reproducible technique but does not provide superior myocardial protection in paediatric heart surgery., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.)