The performance of large language models in intercollegiate Membership of the Royal College of Surgeons examination

INTRODUCTION

Large language models (LLM), such as Chat Generative Pre-trained Transformer (ChatGPT) and Bard utilise deep learning algorithms that have been trained on a massive data set of text and code to generate human-like responses. Several studies have demonstrated satisfactory performance on postgraduate examinations, including the United States Medical Licensing Examination. We aimed to evaluate artificial intelligence performance in Part A of the intercollegiate Membership of the Royal College of Surgeons (MRCS) examination.

METHODS

The MRCS mock examination from Pastest, a commonly used question bank for examinees, was used to assess the performance of three LLMs: GPT-3.5, GPT 4.0 and Bard. Three hundred mock questions were input into the three LLMs, and the responses provided by the LLMs were recorded and analysed. The pass mark was set at 70%.

RESULTS

The overall accuracies for GPT-3.5, GPT 4.0 and Bard were 67.33%, 71.67% and 65.67%, respectively (p = 0.27). The performances of GPT-3.5, GPT 4.0 and Bard in Applied Basic Sciences were 68.89%, 72.78% and 63.33% (p = 0.15), respectively. Furthermore, the three LLMs obtained correct answers in 65.00%, 70.00% and 69.17% of the Principles of Surgery in General questions (p = 0.67). There were no differences in performance in the overall and subcategories among the three LLMs.

CONCLUSIONS

Our findings demonstrated satisfactory performance for all three LLMs in the MRCS Part A examination, with GPT 4.0 the only LLM that achieved the pass mark set.

Surgical outcomes and optimal approach to treatment of aortic valve endocarditis with aortic root abscess - systematic review and meta-analysis

BACKGROUND

Data on the postoperative outcomes for patients with infective endocarditis complicated by an aortic root abscess is sparse due to the condition's low incidence and high mortality rates. This systematic review and meta-analysis aims to evaluate existing data on the impact of aortic root abscesses on the postoperative outcomes and to inform optimal surgical approach.

METHODS

The online databases MEDLINE, EMBASE and Cochrane library were searched from 1990 to 2022 for studies comparing cohorts of surgically managed infective endocarditis patients with and without an aortic root abscess. Data was extracted by two independent investigators and aggregated in a random-effects model. Risk of bias was assessed using an adapted version of the Newcastle-Ottawa scale.

RESULTS

Six clinical studies were included in the meta-analysis (n 1982). The abscess group was associated with increased in-hospital mortality (OR 1.74 95%: CI 1.18-2.56) and late mortality (HR 1.27 95% CI:1.03-1.58). The reoperation meta-analysis was complicated by high rates of heterogeneity (I2 = 59%) and found no significant differences in reoperation between abscess and no abscess groups (HR=1.48: 95% CI:0.92-2.40). Post-hoc scatter graph showed a strong linear relationship (r 0.998), suggesting hospitals with higher rates of aortic root replacement achieve lower rates of reoperation for aortic root abscess patients compared with patch reconstruction.

CONCLUSIONS

The presence of an aortic root abscess in aortic valve endocarditis is associated with elevated early and late mortality despite modern standards of care. Additionally, aortic root replacement should be considered to have a favourable postoperative profile for use in this context.

Efficacy of propofol-supplemented cardioplegia on biomarkers of organ injury in patients having cardiac surgery using cardiopulmonary bypass: a statistical analysis plan for the ProMPT-2 randomised controlled trial

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.

Trend in mitral valve prostheses of choice and early outcomes in the United Kingdom

OBJECTIVE

Despite the superiority of mitral valve repair, surgical mitral valve replacement (SMVR) remains an important intervention for patients with valve stenosis, infective endocarditis and complex mitral valve degeneration. There has been an increasing popularity in the worldwide use of biological valves due to the avoidance of long-term anti-coagulation and recent advancements in transcatheter techniques. We aim to evaluate the trend, early clinical outcomes and the choice of prostheses use in isolated SMVR over a 23 years period in the United Kingdom.

METHODS

All patients (n = 13,147) who underwent elective or urgent isolated SMVR from March 1996 to April 2019 were identified from the National Adult Cardiac Surgery Audit database. Trends in clinical outcomes, predicted/observed mortality of patients and the utilization of biological prostheses across 5 different age groups: <50, 50-59, 60-69, 70-79 and ≥80 years old were investigated. Early clinical outcomes associated with the use of mechanical and biological mitral valve prostheses in patients between the age of 60-70 years old were analysed.

RESULTS

The number of isolated SMVR performed has remained stable with approximately 600 cases annually since 2010. The in-hospital/30-day mortality rate has decreased from 7.41% (1996) to 3.92% (2018), despite the EuroScore II increasing from 1.42% in 1996 to 2.43% in 2018. Biological prostheses usage increased across all age group, and particularly in the 60-69 and 70-79 group, from 17.86% and 53.85% in 1996 to 48.85% and 82.38% in 2018, respectively. The use of mechanical prostheses was reduced in patients between the age of 50-59 from 100% in 1996 to 80.65% in 2018. There were no differences in short term outcomes among patients aged 60-70 years who received either a biological or mechanical prostheses.

CONCLUSION

There has been a significant reduction in surgical mitral valve replacement early in-hospital mortality, despite an observed increase in the risk profile of patients over 23 years. A shifting trend in valve replacement choices was observed with a rise in the use of biological prostheses, particularly within the 60-69 and 70-79 age group. Early in hospital outcomes for patients aged 60-70 were not determined by the implanted valve type.

Effect of on-pump vs. off-pump coronary artery bypass grafting in patients with non-dialysis-dependent severe renal impairment: propensity-matched analysis from the UK registry dataset

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.

Hypobaric type oxygenators - physics and physiology

Brain injury is still a serious complication after cardiac surgery. Gaseous microemboli (GME) are known to contribute to both short and longer-term brain injury after cardiac surgery. Hypobaric and novel dual-chamber oxygenators use the physical behaviors and properties of gases to reduce GME. The aim of this review was to present the basic physics of the gases, the mechanism in which the hypobaric and dual-chamber oxygenators reduce GME, their technical performance, the preclinical studies, and future directions. The gas laws are reviewed as an aid to understanding the mechanisms of action of oxygenators. Hypobaric-type oxygenators employ a high oxygen, no nitrogen environment creating a steep concentration gradient of nitrogen out of the blood and into the oxygenator, reducing the risk of GMEs forming. Adequately powered clinical studies have never been carried out with a hypobaric or dual-chamber oxygenator. These are required before such technology can be recommended for widespread clinical use.

Impact of explanted valve type on aortic valve reoperations: nationwide UK experience

OBJECTIVES

This nationwide retrospective cohort study assessed the impact of the explanted valve type on reoperative outcomes in aortic valve surgery within the UK over a 23-year period.

METHODS

Data were sourced from the National Institute for Cardiovascular Outcomes Research (NICOR) database. All patients undergoing first-time isolated reoperative aortic valve replacement between 1996 and 2019 in the UK were included. Concomitant procedures, homograft implantation or aortic root enlargement were excluded. Propensity score matching was utilized to compare outcomes and risk factors for in-hospital mortality was evaluated through multivariable logistic regression. Final model selection was conducted using Akaike Information Criterion through bootstrapping. The primary end point was in-hospital mortality, and secondary end points included postoperative morbidities.

RESULTS

Out of 2371 patients, 24.9% had mechanical and 75% had bioprosthetic valves implanted during the primary procedure. Propensity matched groups of 324 patients each, were compared. In-hospital mortality for mechanical and bioprosthetic valve explants was 7.1% and 5.9%, respectively (P = 0.632). On multivariable logistic regression analysis, valve type was not a risk factor for mortality [odds ratio (OR) 0.62, 95% confidence interval (CI) 0.37-1.05; P = 0.1]. Age (OR 1.03, 95% CI 1.01-1.05; P < 0.05), left ventricular ejection fraction (OR 1.62, 95% CI 1.08-2.42; P < 0.05), creatinine ≥ 200 mg/dl (OR 2.21, 95% CI 1.17-4.04; P < 0.05) and endocarditis (OR 2.66, 95% CI 1.71-4.14; P < 0.05) emerged as risk factors for mortality.

CONCLUSIONS

The type of valve initially implanted (mechanical or bioprosthetic) did not determine mortality. Instead, age, left ventricular ejection fraction, renal impairment and endocarditis were significant risk factors for in-hospital mortality.

Stroke after Cardiac Surgery: A Risk Factor Analysis of 580,117 Patients from UK National Adult Cardiac Surgical Audit Cohort

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.

A systematic review and meta-analysis of internal thoracic artery harvesting techniques: Skeletonized vs pedicled

OBJECTIVES

The aim of this meta-analysis was to compare clinical and angiographic outcomes of skeletonized versus pedicled internal thoracic artery for coronary artery bypass grafting.

METHODS

A comprehensive search on Ovid MEDLINE, Ovid EMBASE and Scopus was performed from inception to December 2022. The primary outcome was follow-up mortality and graft failure. Secondary outcomes were repeat revascularization, cardiovascular death and operative mortality, myocardial infarction, stroke, and sternal wound complications (SWCs). Pooled estimate for follow-up outcomes was summarized as incidence rate ratio (IRR) and 95% confidence interval (CI) while short-term outcomes were pooled as odds ratio (OR) and 95% CI. For all outcomes, inverse variance weighting was used for pooling.

RESULTS

Twenty-eight studies, including 7 randomized trials and 21 observational studies, for a total of 5664 patients in the skeletonized group and 7434 in the pedicled group, were included in the analysis. At a mean weighted follow-up of 4.8 years, there was no difference in mortality between the two groups (IRR 1.14; 95% CI 0.59-2.20). However, the skeletonized group had a higher incidence of graft failure compared to the pedicled group (IRR 1.87, 95% CI 1.33-2.63) but a lower risk of SWCs (OR 0.42; 95% CI 0.30-0.60). There was no difference in short-term outcomes.

CONCLUSIONS

Compared to the pedicled harvesting technique, skeletonization of the internal thoracic artery is associated with higher rate of graft failure and lower risk of SWCs without mortality difference.

In-hospital outcomes predictors and trends of redo sternotomy aortic root replacements: insights from a UK registry analysis

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.

Osteopontin Activation and Microcalcification in Venous Grafts Can Be Modulated by Dexamethasone

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 18F-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. 18F-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.

Development and Evaluation of a Natural Language Processing System for Curating a Trans-Thoracic Echocardiogram (TTE) Database

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 R2 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.

Sex-Based Differences in Early Outcomes Following Mitral Valve Surgery for Degenerative Disease

OBJECTIVES

To determine whether sex-based differences exist following surgery for degenerative mitral valve disease.

METHODS

Using a national database, we analysed data on mitral valve surgery for degenerative disease (n = 22,658) between January 2000 and March 2019 in the UK. We split the cohort into men (n = 14,681) and women (n = 7977) and compared background characteristics, intraoperative variables and early postoperative outcomes. Our primary outcome was hospital mortality; secondary outcomes included re-exploration for bleeding, prolonged admission (>10 days) and mitral replacement. We used binary logistic regression models for all outcomes, with multiplicative interaction terms to determine the nature of any differences.

RESULTS

Women presented older (70 ± 11 years vs. 67 ± 11 years, p < 0.001) with worse symptom profiles (New York Heart Association Class III-IV 57% vs. 44%, p < 0.001). They had higher rates of preoperative atrial fibrillation (39% vs. 35%, p < 0.001) and tricuspid disease requiring surgery (21% vs. 15%, p < 0.001). They had lower repair rates (66% vs. 76%, p < 0.001), higher mortality (3% vs. 2%, p < 0.001) and were more likely to have a prolonged admission (48% vs. 40%, p < 0.001). Female sex was an independent predictor of mortality (odds ratio (OR): 1.52, 95% CI: 1.21-1.90, p < 0.001). Age and Canadian Cardiovascular Society (CCS) score showed significant interactions with sex. The relationship between advancing age and mortality was found to be more pronounced in women.

CONCLUSIONS

(1) Female sex is an independent predictor of hospital mortality, prolonged hospital admission and mitral valve replacement. (2) The relationship between female sex and mortality is exacerbated by worsening CCS score and advancing age. (3) Women have significantly lower repair rates.

Trends and outcomes of concomitant aortic valve replacement and coronary artery bypass grafting in the UK and a survey of practices

OBJECTIVES

Concomitant revascularization of coronary artery disease at the same time as treatment for aortic valvopathy favourably impacts survival. However, combined surgery may be associated with increased adverse outcomes compared to aortic valve replacement (AVR) or coronary artery bypass grafting in isolation.

METHODS

We retrospectively analyzed all patients who underwent AVR with bypass grafting between February 1996 and March 2019 using data from the National Adult Cardiac Surgery Audit. We used a generalized mixed-effects model to assess the effect of the number and type of bypass grafts associated with surgical AVR on in-hospital mortality, postoperative stroke, and the need for renal dialysis. Furthermore, we conducted an international cross-sectional survey of cardiac surgeons to explore their views about concomitant AVR with coronary bypass grafting interventions.

RESULTS

Fifty-one thousand two hundred and seventy-two patients were included in the study. Patients receiving 2 or more bypass grafts demonstrated more significant preoperative comorbidity and disease severity. Patients undergoing 2 and >2 grafts in addition to AVR had increased mortality as compared to patients undergoing AVR and only 1 graft [odds ratio (OR) 1.17, 95% confidence interval (CI) [1.05-1.30], P = 0.005 and OR 1.15, 95% CI [1.02-1.30], P = 0.024 respectively]. A single arterial conduit was associated with a reduction in mortality (OR 0.75, 95% CI [0.68-0.82], P < 0.001) and postoperative dialysis (OR 0.87, 95% CI [0.78-0.96], P = 0.006), but this association was lost with >1 arterial conduit. One hundred and three surgeons responded to our survey, with only a small majority believing that the number of bypass grafts can influence short- or long-term postoperative outcomes in these patients, and an almost equal split in responders supporting the use of staged or hybrid interventions for patients with concomitant pathology.

CONCLUSIONS

The number of grafts performed during combined AVR and coronary artery bypass grafting is associated with increased morbidity and mortality. The use of an arterial graft was also associated with reduced mortality. Future studies are needed to assess the effect of incomplete revascularization and measure long-term outcomes. Based on our data, current published evidence, and the collective expert opinion we gathered, we endorse future work to investigate the short and long-term efficacy and safety of hybrid intervention for patients with concomitant advanced coronary and aortic valve disease.

Risk Factors and Outcomes of Reoperative Surgical Aortic Valve Replacement in the United Kingdom

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.

Subclinical Leaflet Thrombosis Following Surgical and Transcatheter Aortic Valve Replacement: A Meta-Analysis

Subclinical leaflets valve thrombosis (SLT) is a recently identified phenomenon with multidetector computer tomography after tissue aortic valve replacement. Whether SLT is more frequent after transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) is currently not known. Thus, the aim of this pairwise meta-analysis was to investigate the incidence of SLT after both TAVR and SAVR, the association with anticoagulation therapy, and the risk for neurological events. We searched PubMed, Google Scholar, and Ovid MEDLINE/Embase (January 02, 2023, last update) (PROSPERO registration: CRD42022383295). Statistical analysis was performed according to a prespecified statistical analysis plan. Time-to-event outcomes were summarized as incidence rate ratios (IRR). Pooled estimates were calculated using inverse variance method and random effect model. Overall, 2 registries, 2 randomized trials, and 1 observational study (1,593 patients) were included in this meta-analysis. There was a statistically significant difference in the incidence rate at follow-up of SLT between patients who underwent TAVR and SAVR (IRR 2.07, 95% confidence interval [CI]: [1.06; 4.03], I2 79%, 95% CI: [44; 92], p = 0.03). Oral anticoagulation therapy was associated with a reduced incidence of SLT (IRR 7.51, 95% CI: [3.24; 17.37], I2 62%, 95% CI: [0; 87], p <0.001). However, the incidence of later neurological events did not differ between patients with or without SLT (IRR 1.05, 95% CI: [0.32; 3.47], p = 0.93). In conclusion, SLT was more frequently detected after TAVR than SAVR. However, it was not associated with an increased risk for neurological events. Oral anticoagulation therapy seemed to reduce the incidence of SLT.

Data standards for transcatheter aortic valve implantation: the European Unified Registries for Heart Care Evaluation and Randomised Trials (EuroHeart)

AIMS

Standardized data definitions are necessary for the quantification of quality of care and patient outcomes in observational studies and randomised controlled trials (RCTs). The European Unified Registries for Heart Care Evaluation and Randomised Trials (EuroHeart) project of the European Society of Cardiology (ESC) aims to create pan-European data standards for cardiovascular diseases and interventions, including transcatheter aortic valve implantation (TAVI).

METHODS AND RESULTS

We followed the EuroHeart methodology for cardiovascular data standard development. A Working Group of 29 members representing 12 countries was established and included a patient representative, as well as experts in the management of valvular heart disease from the European Association of Percutaneous Cardiovascular Interventions (EAPCI), the European Association of Cardiovascular Imaging (EACVI) and the Working Group on Cardiovascular Surgery. We conducted a systematic review of the literature and used a modified Delphi method to reach consensus on a final set of variables. For each variable, the Working Group provided a definition, permissible values, and categorized the variable as mandatory (Level 1) or additional (Level 2) based on its clinical importance and feasibility. In total, 93 Level 1 and 113 Level 2 variables were selected, with the level 1 variables providing the dataset for registration of patients undergoing TAVI on the EuroHeart IT platform.

CONCLUSION

This document provides details of the EuroHeart data standards for TAVI processes of care and in-hospital outcomes. In the context of EuroHeart, this will facilitate quality improvement, observational research, registry-based RCTs and post-marketing surveillance of devices, and pharmacotherapies.

ONE-SENTENCE SUMMARY

The EuroHeart data standards for transcatheter aortic valve implantation (TAVI) are a set of internationally agreed data variables and definitions that once implemented will facilitate improvement of quality of care and outcomes for patients receiving TAVI.

Trend and early clinical outcomes of off-pump coronary artery bypass grafting in the UK

OBJECTIVES

The popularity of off-pump coronary artery bypass grafting (CABG) varies across the world, ranging from 20% in Europe and the USA to 56% in Asia. We present the trend and early clinical outcomes in off pump in the UK.

METHODS

All patients who underwent elective or urgent isolated CABG from 1996 to 2019 were extracted from the National Adult Cardiac Surgery Audit database. The trend in operating surgeons and units volume and training in off pump were analysed. Early clinical outcomes between off- and on-pump CABG were compared using propensity score matching.

RESULTS

A total of 351 422 patients were included. The overall off-pump rate during the study period was 15.17%, it peaked in 2008 (19.8%), followed by a steady decreased to 2018 (7.63%). Its adoption varied across centres and surgeons, ranging from <1% to 48.36% and <1% to 85.5%, respectively, of total cases performed. After propensity score matching for the period 1996-2019, off pump, when compared to on pump, was associated with a lower in-hospital/30-day mortality (1.2% vs 1.5%, P < 0.001), return to theatre (3.7% vs 4.5%, P < 0.001), cerebrovascular accident (transient ischaemic attack: 0.3% vs 0.6%, stroke: 0.3% vs 0.6%, P < 0.001) and deep sternal wound infection (0.8% vs 1.2%, P ≤ 0.001). In a sub-analysis from the introduction of EuroScore II (2012-2019), there were no differences in-hospital/30-day mortality (1.0% vs 1.0%, P = 0.71). However, on pump, had a higher return to theatre (4.2% vs 2.7%, P < 0.001), cerebrovascular accident (transient ischaemic attack: 0.4% vs 0.2%, stroke: 0.5% vs 0.3%, P = 0.003) and deep sternal wound infection (1.0% vs 0.6%, P = 0.004).

CONCLUSIONS

Our data show a decreasing trend in the use of off pump in the UK since 2008. This is likely to be multifactorial and raises the question of whether it should be a specialized revascularization technique.

Comparison of machine learning techniques in prediction of mortality following cardiac surgery: analysis of over 220 000 patients from a large national database

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.

Mitral repair versus replacement: 20-year outcome trends in the UK (2000-2019)

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.

Patterns of cytokine release and association with new onset of post-cardiac surgery atrial fibrillation

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.

Efficacy and safety of carbon dioxide insufflation for brain protection for patients undergoing planned left-sided open heart valve surgery: protocol for a multicentre, placebo-controlled, blinded, randomised controlled trial (the CO2 Study)

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.

A review and meta-analysis of conventional sternotomy versus minimally invasive mitral valve surgery for degenerative mitral valve disease focused on the last decade of evidence

OBJECTIVES

Early meta-analyses comparing minimally invasive mitral valve surgery (MIMVS) with conventional sternotomy (CS) have determined the safety of MIMVS. We performed this review and meta-analysis based on studies from 2014 onwards to examine the differences in outcomes between MIMVS and CS. Specifically, some outcomes of interest included renal failure, new onset atrial fibrillation, mortality, stroke, reoperation for bleeding, blood transfusion and pulmonary infection.

METHODS

A systematic search was performed in six databases for studies comparing MIMVS with CS. Although the initial search identified 821 papers in total, nine studies were suitable for the final analysis. All studies included compared CS with MIMVS. The Mantel - Haenszel statistical method was chosen due the use of inverse variance and random effects. A meta-analysis was performed on the data.

RESULTS

MIMVS had significantly lower odds of renal failure (OR: 0.52; 95% CI 0.37 to 0.73, p < 0.001), new onset atrial fibrillation (OR: 0.78; 95% CI 0.67 to 0.90, p < 0.001), reduced prolonged intubation (OR: 0.50; 95% CI 0.29 to 0.87, p = 0.01) and reduced mortality (OR: 0.58; 95% CI 0.38 to 0.87, p < 0.01). MIMVS had shorter ICU stay (WMD: -0.42; 95% CI -0.59 to -0.24, p < 0.001) and shorter time to discharge (WMD: -2.79; 95% CI -3.86 to -1.71, p < 0.001).

CONCLUSION

In the modern era, MIMVS for degenerative disease is associated with improved short-term outcomes when compared to the CS.

Warm versus cold blood cardioplegia in paediatric congenital heart surgery: a randomized trial

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.

Network meta-analysis comparing blood cardioplegia, Del Nido cardioplegia and custodiol cardioplegia in minimally invasive cardiac surgery

INTRODUCTION

Minimally invasive cardiac surgery has been evolving, with the intention of reducing surgical trauma, improve cosmesis and patient satisfaction. Single dose, crystalloid cardioplegia such as Del Nido cardioplegia and Custoidol solution have been increasingly used to reduce the interruption from repeating cardioplegia dosing to minimise the cardiopulmonary bypass and cross clamp time. However, the best cardioplegia for myocardial protection in adult minimally invasive cardiac surgery remains controversial. We aimed to conduct a meta-analysis to analyse the current evidence in the literature.

METHOD

A systematic review and meta-analysis was performed following the updated 2020 PRISMA guideline. Articles published in the five major electronic databases up 1st of April 2021 were identified and reviewed. The primary outcome was in-hospital or 30-day mortality. Traditional pairwise and Bayesian network meta-analyses were conducted.

RESULTS

Nine articles were included in this study. The use of Del Nido cardioplegia was associated with a lower volume of cardioplegia used (Del Nido vs Blood, 1105.62 mL+/-123.47 vs 2569.46 mL+/-1515.52, p<0.001), cardiopulmonary bypass (Del Nido vs Custoidol vs Blood: 91.67+/-14.78 vs 138.05 +/- 21.30 vs 119.38+/-26.91 minutes, p<0.001) and cross-clamp time (Del Nido vs Custoidol vs Blood: 74.99+/-18.55 vs 82.01 +/- 17.28 vs 93.66+/-8.88 minutes, p < 0.001). No differences were observed in the incidence of in-hospital/30-day mortality rate, new onset of atrial fibrillation and stroke. Ranking analysis showed the Custoidol solution has the highest probability to be the first ranked cardioplegia.

CONCLUSION

No differences were found between blood and crystalloid cardioplegia in adult minimally invasive cardiac surgery in several clinical outcomes. The cardioplegia of choice in minimally invasive cardiac surgery remains the surgeons' decision and preference.

Assessment of post-infarct ventricular septal defects through 3D printing and statistical shape analysis

BACKGROUND

Post-infarct ventricular septal defect (PIVSD) is a serious complication of myocardial infarction. We evaluated 3D-printing models in PIVSD clinical assessment and the feasibility of statistical shape modeling for morphological analysis of the defects.

METHODS

Models (n = 15) reconstructed from computed tomography data were evaluated by clinicians (n = 8). Statistical shape modeling was performed on 3D meshes to calculate the mean morphological configuration of the defects.

RESULTS

Clinicians' evaluation highlighted the models' utility in displaying defects for interventional/surgical planning, education/training and device development. However, models lack dynamic representation. Morphological analysis was feasible and revealed oval-shaped (n = 12) and complex channel-like (n = 3) defects.

CONCLUSION

3D-PIVSD models can complement imaging data for teaching and procedural planning. Statistical shape modeling is feasible in this scenario.

Efficacy of propofol-supplemented cardioplegia on biomarkers of organ injury in patients having cardiac surgery using cardiopulmonary bypass: A protocol for a randomised controlled study (ProMPT2)

INTRODUCTION

Cardiac surgery with cardiopulmonary bypass and cardioplegic arrest is known to be responsible for ischaemia and reperfusion organ injury. In a previous study, ProMPT, in patients undergoing coronary artery bypass or aortic valve surgery we demonstrated improved cardiac protection when supplementing the cardioplegia solution with propofol (6 mcg/ml). The aim of the ProMPT2 study is to determine whether higher levels of propofol added to the cardioplegia could result in increased cardiac protection.

METHODS AND ANALYSIS

The ProMPT2 study is a multi-centre, parallel, three-group, randomised controlled trial in adults undergoing non-emergency isolated coronary artery bypass graft surgery with cardiopulmonary bypass. A total of 240 patients will be randomised in a 1:1:1 ratio to receive either cardioplegia supplementation with high dose of propofol (12 mcg/ml), low dose of propofol (6 mcg/ml) or placebo (saline). The primary outcome is myocardial injury, assessed by serial measurements of myocardial troponin T up to 48 hours after surgery. Secondary outcomes include biomarkers of renal function (creatinine) and metabolism (lactate).

ETHICS AND DISSEMINATION

The trial received research ethics approval from South Central - Berkshire B Research Ethics Committee and Medicines and Healthcare products Regulatory Agency in September 2018. Any findings will be shared though peer-reviewed publications and presented at international and national meetings. Participants will be informed of results through patient organisations and newsletters.

TRIAL REGISTRATION

ISRCTN15255199. Registered in March 2019.

Cardiac surgery risk prediction using ensemble machine learning to incorporate legacy risk scores: A benchmarking study

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.

Outcome Monitoring After Cardiac Surgery (OMACS): a single-centre prospective cohort study of cardiac surgery patients

INTRODUCTION

More than 30 000 cardiac surgery procedures are performed in the UK each year, however, postoperative complications and long-term failure of interventions are common, leading to repeated surgeries. This represents a significant burden on the patient and health service.Routinely, patients are discharged to their general practitioner 6 weeks postoperatively and research studies typically only report short-term outcomes up to 1 year after surgery, together this makes long-term outcomes of cardiac surgery difficult to monitor. Further, traditional research methods have yet to advance understanding of what causes early complications and why surgical interventions fail.

METHODS AND ANALYSIS

This prospective cohort study will characterise participants undergoing cardiac surgery at baseline, describe short-term, medium-term and long-term health outcomes postoperatively and collect tissue samples.All eligible adult patients undergoing cardiac surgery at the Bristol Heart Institute, UK will be approached for consent. Recruitment is expected to continue for up to 10 years resulting in the largest cohort of cardiac patients reported to date. Blood, urine and waste tissue samples will be collected during admission. Samples, along with anonymised data, will be used to investigate outcomes and inform predictive models of complications associated with cardiac surgery.Data about the surgical admission will be obtained from hospital databases and medical notes. Participants may be monitored up to 5 years postoperatively using data obtained from NHS digital. Participants will complete health questionnaires 3 months and 12 months postoperatively.The analysis of data and tissue samples to address specific research questions will require separate research protocols and ethical approval.

ETHICS AND DISSEMINATION

This study was approved by the East Midlands Nottingham 2 Research Ethics Committee.Findings will be disseminated through peer-reviewed publications and presentation at national and international meetings. Participants will be informed of results in annual newsletters.

TRIAL REGISTRATION NUMBER

ISRCTN90204321.

On- versus off-pump CABG in octogenarians: A propensity-matched analysis from the UK National Database

INTRODUCTION

Coronary artery bypass grafting (CABG) remains a good revascularization strategy in octogenarians with excellent clinical outcomes and quality of life postoperatively. However, the benefits of off-pump over on-pump CABG in the elderly population are still controversial. We investigated this issue in the UK National Audit database.

METHOD

We retrospectively analyzed all octogenarians undergoing nonemergency, isolated CABG from 1996 to 2019. Propensity score matching (PSM) was conducted to adjust for imbalance in the baseline characteristics between the off-pump and on-pump groups. Primary outcome was in-hospital mortality and postoperative cerebrovascular accidents. Secondary outcomes were bleeding requiring reoperation, deep sternal wound infection, and postoperative dialysis.

RESULT

A total of 6436 patients were included for analysis. No differences were observed between off- and on-pump group in-hospital mortality (4% vs. 3.8%, p = .89), return to theater rate (5.4% vs. 6.2%, p = .16) and incidence of deep sternal wound infection (1.1% vs. 1.6%, p = .34). However, octogenarian undergoing off-pump CABG were less likely to experience postoperative transient ischemic attack (TIA)/stroke (1.4% vs. 2.3%, p = .004) but more likely to require renal dialysis (4.8% vs. 3.5%, p = .03).

CONCLUSION

The data show similar in-hospital mortality in octogenarians regardless of the revascularization technique used. Off-pump when compared with on-pump CABG is associated with a lower incidence in postoperative neurological events but a higher need for renal dialysis.

The influence of metabolic syndrome in heart valve intervention. A multi-centric study

BACKGROUND

The effect of metabolic syndrome (MetS), defined as insulin resistance along with two or more of: obesity, atherogenic dyslipidaemia and elevated blood pressure, on postoperative complications after isolated heart valve intervention remains controversial. We hypothesized that MetS may negatively influence the postoperative course in these patients.

METHODS

Patients from 10 cardiac units who underwent isolated valve intervention (mitral ± $\pm $  tricuspid repair/replacement (mitral valve surgery [MVS]) or surgical aortic valve replacement (SAVR), or transcatheter aortic valve replacement (TAVR) were included. MetS was defined according to the World Health Organization criteria. Primary outcome was in-hospital mortality and overall postoperative length of stay (LOS). Relevant postoperative complications were also recorded.

RESULTS

From 2010 to 2019, 17,283 patients underwent valve intervention. The MVS, SVAR, and TAVR accounted for the 39.4%, 48.2%, and 12.3% respectively of the whole. MetS compared to no-MetS was associated to higher mortality in the MVS group (6.5% vs. 2%, p < .001), but not in the SAVR and TAVR group. In both surgical cohorts, MetS was associated with increased complications including red blood cells transfusion, renal failure, mechanical ventilation time, intensive care and overall postoperative LOS (11 (9) vs. 10 (6), p < .001 and 10 (6) versus 10 (5) days, p = .002, MVS and [SAVR]). No differences were found in the TAVR cohort, with similar mortality and complications.

CONCLUSION

MetS was associated to more postoperative complications, with higher mortality in the MVS group. In the TAVR cohort, postoperative complications and mortality rate did not differ between patients with and without MetS, however LOS was longer in the MetS group.

Early mortality and neurologic outcomes following mitral valve surgery in the very elderly

OBJECTIVES

Valve repair is the gold standard for treatment of degenerative mitral valve disease. As the population ages, patients undergoing valve degeneration and therefore considered for mitral valve surgery will naturally be getting older. We sought to evaluate whether mitral repair retained a survival advantage over replacement in patients ≥80 years old.

METHODS

A retrospective cohort study was performed using data acquired from the United Kingdom National Adult Cardiac Surgery Audit for the outcomes of in-hospital mortality and postoperative cerebrovascular event (CVA). Individual multivariable logistic regression models were created to investigate adjusted associations between these outcomes and type of mitral valve operation, repair or replacement. Additionally, associations between the individual model parameters and in-hospital mortality and CVA were investigated.

RESULTS

A total of 1140 patients underwent mitral repair (66.4%, median age 82.3), and 577 patients underwent mitral replacement (33.6%, median age 82.1). The overall age range was 80-92. The incidence of in-hospital mortality favored the repair group (4.4% vs. 8.3%, p = .001). Multivariable logistic regression modeling demonstrated an increased adjusted odds of in-hospital mortality for mitral valve replacement (MVR) (odd ratio [OR]: 2.01, 1.15-3.50, p = .01). The only other parameter associated with an increased adjusted odds of in-hospital mortality was postoperative dialysis (OR: 14.2, 7.67-26.5, p < .001). There was not a demonstrated association between MVR and perioperative CVA (OR: 1.11, 0.49-2.4, p = .8).

CONCLUSIONS

In patients ≥80 years old, mitral valve repair (MVr) was shown to be associated with a decreased adjusted odds of mortality, with a null association with CVA. These results suggest that, if feasible, MVr should remain the preferred management strategy, even in the very elderly.

Females have an increased risk of short-term mortality after cardiac surgery compared to males: Insights from a national database

OBJECTIVES

Female sex is considered a risk factor for mortality and morbidity following cardiac surgery. This study is the first to review the UK adult cardiac surgery national database to compare outcomes following surgical coronary revascularisation and valvular procedures between females and males.

METHODS

Using data from National Adult Cardiac Surgery Audit, we identified all elective and urgent, isolated coronary artery by-pass grafting (CABG), aortic valve replacement (AVR) and mitral valve replacement/repair (MVR) procedures from 2010 to 2018. We compared baseline data, operative data and outcomes of mortality, stroke, renal failure, deep sternal wound infection, return to theater for bleeding, and length of hospital stay. Multivariable mixed-effect logistical/linear regression models were used to assess relationships between sex and outcomes, adjusting for baseline characteristics.

RESULTS

Females, compared to males, had greater odds of experiencing 30-day mortality (CABG odd ratio [OR] 1.76, confidence interval [CI] 1.47-2.09, p < .001; AVR OR 1.59, CI 1.27-1.99, p < .001; MVR OR 1.37, CI 1.09-1.71, p = .006). After CABG, females also had higher rates of postoperative dialysis (OR 1.31, CI 1.12-1.52, p < .001), deep sternal wound infections (OR 1.43, CI 1.11-1.83, p = .005) and longer length of hospital stay (β 1.2, CI 1.0-1.4, p < .001) compared to males. Female sex was protective against returning to theater for postoperative bleeding following CABG (OR 0.76, CI 0.65-0.87, p < .001) and AVR (OR 0.72, CI 0.61-0.84, p < .001).

CONCLUSION

Females in the United Kingdom have an increased risk of short-term mortality after cardiac surgery compared to males. This highlights the need to focus on the understanding of the causes behind these disparities and implementation of strategies to improve outcomes in females.

On the left or on the right…side of the table. Where do you stand?

Being able to perform surgery first-hand represents the backbone of every training program and the key to successful development of the new generation of skilful surgeons. In this issue of the Journal, Comanici et al. presented a thorough systematic summary of the current evidence on the outcomes of cardiothoracic operations performed by trainees. Taking for granted the importance of training young surgeons, it is paramount to identify and tackle any potential obstacles hindering the surgical growth of a trainee.

Implications of elevated troponin on time-to-surgery in non-ST elevation myocardial infarction (NIHR Health Informatics Collaborative: TROP-CABG study)

Implications of elevated troponin on time-to-surgery in non-ST elevation myocardial infarction(NIHR Health Informatics Collaborative:TROP-CABG study). Benedetto et al. BACKGROUND: The optimal timing of coronary artery bypass grafting (CABG) in patients with non-ST elevation myocardial infarction (NSTEMI) and the utility of pre-operative troponin levels in decision-making remains unclear. We investigated (a) the association between peak pre-operative troponin and survival post-CABG in a large cohort of NSTEMI patients and (b) the interaction between troponin and time-to-surgery. METHODS AND RESULTS: Our cohort consisted of 1746 patients (1684 NSTEMI; 62 unstable angina) (mean age 69 ± 11 years,21% female) with recorded troponins that had CABG at five United Kingdom centers between 2010 and 2017. Time-segmented Cox regression was used to investigate the interaction of peak troponin and time-to-surgery on early (within 30 days) and late (beyond 30 days) survival. Average interval from peak troponin to surgery was 9 ± 15 days, with 1466 (84.0%) patients having CABG during the same admission. Sixty patients died within 30-days and another 211 died after a mean follow-up of 4 ± 2 years (30-day survival 0.97 ± 0.004 and 5-year survival 0.83 ± 0.01). Peak troponin was a strong predictor of early survival (adjusted P = 0.002) with a significant interaction with time-to-surgery (P interaction = 0.007). For peak troponin levels <100 times the upper limit of normal, there was no improvement in early survival with longer time-to-surgery. However, in patients with higher troponins, early survival increased progressively with a longer time-to-surgery, till day 10. Peak troponin did not influence survival beyond 30 days (adjusted P = 0.64). CONCLUSIONS: Peak troponin in NSTEMI patients undergoing CABG was a significant predictor of early mortality, strongly influenced the time-to-surgery and may prove to be a clinically useful biomarker in the management of these patients.

Nrf2-Keap-1 imbalance under acute shear stress induces inflammatory response in venous endothelial cells

Vascular endothelial cell stimulation is associated with the activation of different signalling pathways and transcription factors. Acute shear stress is known to induce different pro-inflammatory mediators such as IL-8. Nrf2 is activated by prolonged high shear stress promoting an antiinflammatory and athero-protective environment. However, little is known about the impact of acute shear stress on Nrf2 and Keap1 function and its role in IL-8 regulation. We aimed to examine Nrf2-Keap1 complex activation in-vitro and its role in regulating IL-8 transcripts under acute arterial shear stress (12 dyn/cm2) in venous endothelial cells (ECs). We note that acute high shear stress caused a significant upregulation of Nrf2 target genes, HO-1 and GCLM and an increased IL-8 upregulation at 90 and 120 minutes. Mechanistically, acute high shear did not affect Nrf2 nuclear translocation but resulted in reduced nuclear Keap1, suggesting that the reduction in nuclear Keap1 may result in increased free nuclear nrf2 to induce transcription. Consistently, the suppression of Keap1 using shRNA (shKeap1) resulted in significant upregulation of IL-8 transcripts in response to acute shear stress. Interestingly; the over expression of Nrf2 using Nrf2-Ad-WT or Sulforaphane was also associated with significant upregulation of IL-8 compared to controls. This study highlights the role of Keap1 in Nrf2 activation under shear stress and indicates that activation of Nrf2 may be deleterious in ECs in the context of acute haemodynamic injury.

Pathology-related changes in cardiac energy metabolites, inflammatory response and reperfusion injury following cardioplegic arrest in patients undergoing open-heart surgery

Introduction

Changes in cardiac metabolites in adult patients undergoing open-heart surgery using ischemic cardioplegic arrest have largely been reported for non-ventricular tissue or diseased left ventricular tissue, with few studies attempting to assess such changes in both ventricular chambers. It is also unknown whether such changes are altered in different pathologies or linked to the degree of reperfusion injury and inflammatory response. The aim of the present work was to address these issues by monitoring myocardial metabolites in both ventricles and to establish whether these changes are linked to reperfusion injury and inflammatory/stress response in patients undergoing surgery using cold blood cardioplegia for either coronary artery bypass graft (CABG, n = 25) or aortic valve replacement (AVR, n = 16).

Methods

Ventricular biopsies from both left (LV) and right (RV) ventricles were collected before ischemic cardioplegic arrest and 20 min after reperfusion. The biopsies were processed for measuring selected metabolites (adenine nucleotides, purines, and amino acids) using HPLC. Blood markers of cardiac injury (Troponin I, cTnI), inflammation (IL- 6, IL-8, Il-10, and TNFα, measured using Multiplex) and oxidative stress (Myeloperoxidase, MPO) were measured pre- and up to 72 hours post-operatively.

Results

The CABG group had a significantly shorter ischemic cardioplegic arrest time (38.6 ± 2.3 min) compared to AVR group (63.0 ± 4.9 min, p = 2 x 10-6). Cardiac injury (cTnI release) was similar for both CABG and AVR groups. The inflammatory markers IL-6 and Il-8 were significantly higher in CABG patients compared to AVR patients. Metabolic markers of cardiac ischemic stress were relatively and significantly more altered in the LV of CABG patients. Comparing diabetic and non-diabetic CABG patients shows that only the RV of diabetic patients sustained major ischemic stress during reperfusion and that diabetic patients had a significantly higher inflammatory response.

Discussion

CABG patients sustain relatively more ischemic stress, systemic inflammatory response and similar injury and oxidative stress compared to AVR patients despite having significantly shorter cross-clamp time. The higher inflammatory response in CABG patients appears to be at least partly driven by a higher incidence of diabetes amongst CABG patients. In addition to pathology, the use of cold blood cardioplegic arrest may underlie these differences.

Surgical outcomes and optimal approach to treatment of aortic valve endocarditis with aortic root abscess

OBJECTIVES

To evaluate the impact of aortic root abscess (ARA) on the postoperative outcomes of surgically managed infective endocarditis (IE) and to inform optimal surgical approach.

METHODS

Between 2009 and 2020, 143 consecutive patients who underwent surgical management for aortic-valve IE were included in a retrospective cohort study. Multivariable and propensity-weighted analyses were used to adjust for demographic imbalances between those without (n = 93; NARA) and with an ARA (n = 50). Additionally, empirical subgroup analysis appraised the two most used surgical techniques; patch reconstruction (PR) and aortic root replacement (ARR).

RESULTS

Demographic characteristics were similar between ARA and NARA except for logistic EuroSCORE, previous valve surgery, and multivalvular infection. In-hospital mortality was 8% and 12% in NARA and ARA, respectively (p = .38), with mortality rates consistently nonsignificantly higher in ARA across all time periods. The overall reoperation rate was also higher in ARA (27% vs. 14%; p = .09) and ARA was shown to be associated with late reoperation (odds ratio [OR] = 2.74; 95% confidence interval [CI] = 1.18-6.36). Patients treated with an ARR showed a 16% increase in late mortality when compared with PR (40% vs. 24%; p = .27) and a 17% lower reoperation rate (14% vs. 31%; p = .24). Propensity-weighted analysis identified ARR as a significant protective factor for reoperation (hazard ratio = 0.05; 95% CI = 0.01-0.34).

CONCLUSIONS

The presence of an ARA in aortic valve endocarditis was not associated with significantly higher early and late mortality but is linked with a higher reoperation rate at our institution. ARR in ARA is protective from reoperation so should be considered best practice in this setting.

To repair or replace-the root dilemma in aortic dissections

Significant dilemma exists regarding the management of the aortic root pathology in acute aortic dissections. Several strategies for both repair and replacement exist and there is a lack of clarity on the superiority of one over the other. Important factors that influence management strategies include involvement of the sinuses, the competence of the aortic valve, the presence of Marfans syndrome, and connective tissue disorders, as well as availability of surgical expertise. The wide variability in these factors makes it unlikely for any one technique to be suitable for the management of all aortic roots pathology.

Challenges and solutions to recruitment of neonates and children having cardiac surgery into a study using a novel sampling device

OBJECTIVE

To narratively describe the challenges and solutions required in delivering a non-commercial study of children undergoing cardiac surgery using a novel subcutaneous hormone collection device.

RESULTS

The challenges faced by the research team are divided into those of conducting healthcare research in children and those specific to this study. Many of the issues of conducting healthcare research in children can and have been overcome by structural and institutional culture change-normalising and embedding research as part of good clinical care. The issues specific to insertion and maintenance of the novel collection device can be overcome by education and support of the clinical teams. The increased incentives and resources of commercial research may have overcome many of these.

Effect of cardioplegic arrest and reperfusion on left and right ventricular proteome/phosphoproteome in patients undergoing surgery for coronary or aortic valve disease

Our earlier work has shown inter‑disease and intra‑disease differences in the cardiac proteome between right (RV) and left (LV) ventricles of patients with aortic valve stenosis (AVS) or coronary artery disease (CAD). Whether disease remodeling also affects acute changes occuring in the proteome during surgical intervention is unknown. This study investigated the effects of cardioplegic arrest on cardiac proteins/phosphoproteins in LV and RV of CAD (n=6) and AVS (n=6) patients undergoing cardiac surgery. LV and RV biopsies were collected during surgery before ischemic cold blood cardioplegic arrest (pre) and 20 min after reperfusion (post). Tissues were snap frozen, proteins extracted, and the extracts were used for proteomic and phosphoproteomic analysis using Tandem Mass Tag (TMT) analysis. The results were analysed using QuickGO and Ingenuity Pathway Analysis softwares. For each comparision, our proteomic analysis identified more than 3,000 proteins which could be detected in both the pre and Post samples. Cardioplegic arrest and reperfusion were associated with significant differential expression of 24 (LV) and 120 (RV) proteins in the CAD patients, which were linked to mitochondrial function, inflammation and cardiac contraction. By contrast, AVS patients showed differential expression of only 3 LV proteins and 2 RV proteins, despite a significantly longer duration of ischaemic cardioplegic arrest. The relative expression of 41 phosphoproteins was significantly altered in CAD patients, with 18 phosphoproteins showing altered expression in AVS patients. Inflammatory pathways were implicated in the changes in phosphoprotein expression in both groups. Inter‑disease comparison for the same ventricular chamber at both timepoints revealed differences relating to inflammation and adrenergic and calcium signalling. In conclusion, the present study found that ischemic arrest and reperfusion trigger different changes in the proteomes and phosphoproteomes of LV and RV of CAD and AVS patients undergoing surgery, with markedly more changes in CAD patients despite a significantly shorter ischaemic period.

Large animal model of vein grafts intimal hyperplasia: A systematic review

Coronary artery bypass grafting remains the treatment of choice for a large cohort of patients with significant coronary disease. Despite the increased use of arterial grafts, the long saphenous vein remains the most commonly used conduit. Long-term graft patency continues to be the Achilles heel of saphenous vein grafts. This is due to the development of intimal hyperplasia, a chronic inflammatory disease that results in the narrowing and occlusion of a significant number of vein grafts. Research models for intimal hyperplasia are essential for a better understanding of pathophysiological processes of this condition. Large animal models resemble human anatomical structures and have been used as a surrogate to study disease development and prevention over the years. In this paper, we systematically review all published studies that utilized large animal models of vein graft disease with a focus on the type of model and any therapeutic intervention, specifically the use of external stents/mesh.

Modelling the dynamic interaction of systemic inflammation and the hypothalamic-pituitary-adrenal (HPA) axis during and after cardiac surgery

Major surgery and critical illness produce a potentially life-threatening systemic inflammatory response. The hypothalamic-pituitary-adrenal (HPA) axis is one of the key physiological systems that counterbalances this systemic inflammation through changes in adrenocorticotrophic hormone (ACTH) and cortisol. These hormones normally exhibit highly correlated ultradian pulsatility with an amplitude modulated by circadian processes. However, these dynamics are disrupted by major surgery and critical illness. In this work, we characterize the inflammatory, ACTH and cortisol responses of patients undergoing cardiac surgery and show that the HPA axis response can be classified into one of three phenotypes: single-pulse, two-pulse and multiple-pulse dynamics. We develop a mathematical model of cortisol secretion and metabolism that predicts the physiological mechanisms responsible for these different phenotypes. We show that the effects of inflammatory mediators are important only in the single-pulse pattern in which normal pulsatility is lost-suggesting that this phenotype could be indicative of the greatest inflammatory response. Investigating whether and how these phenotypes are correlated with clinical outcomes will be critical to patient prognosis and designing interventions to improve recovery.

"Time is aorta?": Timeliness of surgical repair in type A aortic dissection

Acute type A aortic dissection is a life‐threatening event that requires prompt management, a complex interaction among the timing of aortic surgical repair, presence or absence of organ malperfusion, and surgical outcomes exists. Whether resection of intimal entry tear should be deferred after reversal of malperfusion and end‐organ ischemia is a matter of controversy. In fact, the timing of aortic repair should be considered within the clinical presentation and baseline characteristics of each patient. Moreover, every effort should be made to minimize times between symptom onset, diagnosis, and surgery.

Sex-specific differences and postoperative outcomes of minimally invasive and sternotomy valve surgery

OBJECTIVES

Female sex is an established risk factor for postoperative complications after heart surgery, but the influence of sex on outcomes after minimally invasive cardiac surgery (MICS) for valvular replacement/repair remains controversial. We examined whether the role of sex as a risk factor varies by surgical approach [MICS vs conventional sternotomy (ST)] and further assessed outcomes among female patients including in-hospital mortality and postoperative complications by surgical approach.

METHODS

We analysed data from a multicentre registry for patients who underwent isolated aortic valve and mitral surgery with MICS or ST. The primary outcome was in-hospital mortality. Propensity score matching was used to minimize between-group differences.

RESULTS

Among the 15 155 patients included in the study, 7674 underwent MICS (50.6%). Female sex was equally distributed in the MICS and ST groups (47.3% vs 47.6%, respectively). Risk for surgery was higher in the ST group than in the MICS group {EuroSCORE II: 4.0 [standard deviation (SD): 6.8] vs 3.7 [SD: 6.4]; P = 0.005}, including among female patients only [ST vs MICS 4.6 (SD: 6.9) vs 4.2 (SD: 6.3); P = 0.04]. Mortality did not significantly vary by procedure among women [MICS vs ST, 2.4% vs 2.8%; hazard ratio 1.09, 95% confidence interval 0.71-1.73; P (surgical approach × sex) = 0.51]. The results also did not vary after adjusting for confounders.

CONCLUSIONS

Female sex was associated with higher mortality in patients undergoing valve surgery, regardless of surgical approach. In female patients, MICS did not provide any benefits over ST in terms of in-hospital deaths or postoperative complications.

SUBJECT COLLECTION

117, 125.

Surgical transcatheter valve implantation: The more pathways, the better

Transcatheter aortic valve implantation (TAVI) is rapidly spreading across the world with the endorsement of the cardiological community and the supporting results of randomized controlled trials. However, TAVI-related complications like aortic dissection, aortic valvular rupture, or left ventricle perforation are still potentially catastrophic.