Randomized trial of routine versus on-demand intraoperative extracorporeal membrane oxygenation in lung transplantation: A feasibility study.

In most centers, extracorporeal membrane oxygenation (ECMO) is the preferred means to provide cardiopulmonary support during lung transplantation. However, there is controversy about whether intraoperative venoarterial (VA) ECMO should be used routinely or selectively. A randomized controlled trial is the best way to address this controversy. In this publication, we describe a feasibility study to assess the practicality of a protocol comparing routine versus selective VA-ECMO during lung transplantation. This prospective, single-center, randomized controlled trial screened all patients undergoing lung transplantation. Exclusion criteria include retransplantation, multiorgan transplantation, and cases where ECMO is mandatory. We determined that the trial would be feasible if we could recruit 19 participants over 6 months with less than 10% protocol violations. Based on the completed feasibility study, we conclude that the protocol is feasible and safe, giving us the impetus to pursue a multicenter trial with little risk of failure due to low recruitment.

Extending the age criteria of lung transplant donors to 70+ years old does not significantly affect recipient survival.

OBJECTIVES: To determine the impact of older donor age (70+ years) on long-term survival and freedom from chronic lung allograft dysfunction in lung transplant (LTx) recipients. METHODS: A retrospective single-center study was performed on all LTx recipients from 2002 to 2017 and a modern subgroup from 2013 to 2017. Recipients were stratified into 4 groups based on donor lung age (<18, 18-55, 56-69, ≥70 years). Donor and recipient characteristics were compared using χ2 tests for differences in proportions and analysis of variance for differences in means. Univariable and multivariable Cox regression was used to describe differences in long-term survival and freedom from chronic lung allograft dysfunction. RESULTS: Between 2002 and 2017, 1600 LTx were performed, 98 of which were performed from donors aged 70 years or older. Recipients of 70+ years donor lungs were significantly older with a mean age of 55.5 ± 12.9 years old (P = .001) and had more Status 3 (urgent) recipients (37.4%, P = .002). After multivariable regression, there were no significant differences in survival or freedom from chronic lung allograft dysfunction between the 4 strata of recipients. CONCLUSIONS: Lung transplantation using donors 70 years old or older can be considered when all other parameters suggest excellent donor lung function without compromising short- or long-term outcomes.

Enhancing preoperative assessment in chronic thromboembolic pulmonary hypertension: A comprehensive analysis of interobserver agreement and proximity-based CT pulmonary angiography scoring.

Background: Surgical risk in chronic thromboembolic pulmonary hypertension (CTEPH) depends on the proximity of thromboembolism on CT pulmonary angiography (CTPA). We assessed interobserver agreement for the quantification of thromboembolic lesions in CTEPH using a novel CTPA scoring index. Methods: Forty CTEPH patients (mean age, 58 ± 16 years; 19 men) with preoperative CTPA who underwent pulmonary endarterectomy (PEA) (08/2020-09/2021) were retrospectively included. Three radiologists scored each CTPA for chronic thromboembolism (occlusions, eccentric thickening, webs) using a 32-vessel model of the pulmonary vasculature, with interobserver agreement evaluated using Fleiss' kappa. CT level of disease was determined by the most proximal chronic thromboembolism: level 1 (main pulmonary artery), 2 (lobar), 3 (segmental) and 4 (subsegmental), and compared to surgical level at PEA. Results: Interobserver agreement for CT level of disease was moderate overall (κ = 0.52). Agreement was substantial overall at the main/lobar level (κ, mean = 0.71) when excluding the left upper lobe (κ = 0.17). Though segmental and subsegmental agreement suffered (κ = 0.31), we found substantial agreement for occlusions (κ = 0.72) compared to eccentric thickening (κ = 0.45) and webs (κ = 0.14). Correlation between CT level and surgical level was strong overall (τb = 0.73) and in the right lung (τb = 0.68), but weak in the left lung (τb = 0.42) (p < 0.05). Radiologists often over- and underestimated the proximal extent of disease in right and left lung, respectively. Conclusions: CT level of disease demonstrated good agreement between radiologists and was highly predictive of the surgical level in CTEPH. Occlusions were the most reliable sign of chronic thromboembolism and are important in assessing the segmental vasculature.

A machine-learning approach to human ex vivo lung perfusion predicts transplantation outcomes and promotes organ utilization.

Ex vivo lung perfusion (EVLP) is a data-intensive platform used for the assessment of isolated lungs outside the body for transplantation; however, the integration of artificial intelligence to rapidly interpret the large constellation of clinical data generated during ex vivo assessment remains an unmet need. We developed a machine-learning model, termed InsighTx, to predict post-transplant outcomes using n = 725 EVLP cases. InsighTx model AUROC (area under the receiver operating characteristic curve) was 79 ± 3%, 75 ± 4%, and 85 ± 3% in training and independent test datasets, respectively. Excellent performance was observed in predicting unsuitable lungs for transplantation (AUROC: 90 ± 4%) and transplants with good outcomes (AUROC: 80 ± 4%). In a retrospective and blinded implementation study by EVLP specialists at our institution, InsighTx increased the likelihood of transplanting suitable donor lungs [odds ratio=13; 95% CI:4-45] and decreased the likelihood of transplanting unsuitable donor lungs [odds ratio=0.4; 95%CI:0.16-0.98]. Herein, we provide strong rationale for the adoption of machine-learning algorithms to optimize EVLP assessments and show that InsighTx could potentially lead to a safe increase in transplantation rates.

Association of Circulating Tumor DNA Testing Before Tissue Diagnosis With Time to Treatment Among Patients With Suspected Advanced Lung Cancer: The ACCELERATE Nonrandomized Clinical Trial.

Importance: Liquid biopsy has emerged as a complement to tumor tissue profiling for advanced non-small cell lung cancer (NSCLC). The optimal way to integrate liquid biopsy into the diagnostic algorithm for patients with newly diagnosed advanced NSCLC remains unclear. Objective: To evaluate the use of circulating tumor DNA (ctDNA) genotyping before tissue diagnosis among patients with suspected advanced NSCLC and its association with time to treatment. Design, Setting, and Participants: This single-group nonrandomized clinical trial was conducted among 150 patients at the Princess Margaret Cancer Centre-University Health Network (Toronto, Ontario, Canada) between July 1, 2021, and November 30, 2022. Patients referred for investigation and diagnosis of lung cancer were eligible if they had radiologic evidence of advanced lung cancer prior to a tissue diagnosis. Interventions: Patients underwent plasma ctDNA testing with a next-generation sequencing (NGS) assay before lung cancer diagnosis. Diagnostic biopsy and tissue NGS were performed per standard of care. Main Outcome and Measures: The primary end point was time from referral to treatment initiation among patients with advanced nonsquamous NSCLC using ctDNA testing before diagnosis (ACCELERATE [Accelerating Lung Cancer Diagnosis Through Liquid Biopsy] cohort). This cohort was compared with a reference cohort using standard tissue genotyping after tissue diagnosis. Results: Of the 150 patients (median age at diagnosis, 68 years [range, 33-91 years]; 80 men [53%]) enrolled, 90 (60%) had advanced nonsquamous NSCLC. The median time to treatment was 39 days (IQR, 27-52 days) for the ACCELERATE cohort vs 62 days (IQR, 44-82 days) for the reference cohort (P < .001). Among the ACCELERATE cohort, the median turnaround time from sample collection to genotyping results was 7 days (IQR, 6-9 days) for plasma and 23 days (IQR, 18-28 days) for tissue NGS (P < .001). Of the 90 patients with advanced nonsquamous NSCLC, 21 (23%) started targeted therapy before tissue NGS results were available, and 11 (12%) had actionable alterations identified only through plasma testing. Conclusions and Relevance: This nonrandomized clinical trial found that the use of plasma ctDNA genotyping before tissue diagnosis among patients with suspected advanced NSCLC was associated with accelerated time to treatment compared with a reference cohort undergoing standard tissue testing. Trial Registration: ClinicalTrials.gov Identifier: NCT04863924.

Impact of sex on outcome after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.

BACKGROUND: The impact of sex on long-term outcomes after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (PH) remains unclear. We therefore examined the early and long-term outcome after PEA to determine whether sex had an impact on the risk of residual PH and need for targeted PH medical therapy. METHODS: Retrospective study of 401 consecutive patients undergoing PEA at our institution between August 2005 and March 2020 was performed. Primary outcome was the need for targeted PH medical therapy postoperatively. Secondary outcomes included survival and measures of hemodynamic improvement. RESULTS: Females (N = 203, 51%) were more likely to have preoperative home oxygen therapy (29.6% vs 11.6%, p < 0.01), and to present with segmental and subsegmental disease compared to males (49.2% vs 21.2%, p < 0.01). Despite similar preoperative values, females had higher postoperative pulmonary vascular resistance (final total pulmonary vascular resistance after PEA, 437 Dynes∙s∙cm-5 vs 324 Dynes∙s∙cm-5 in males, p < 0.01). Although survival at 10 years was not significantly different between sexes (73% in females vs 84% in males, p = 0.08), freedom from targeted PH medical therapy was lower in females (72.9% vs 89.9% in males at 5 years, p < 0.001). Female sex remained an independent factor affecting the need for targeted PH medical therapy after PEA in multivariate analysis (HR 2.03, 95%CI 1.03-3.98, p = 0.04). CONCLUSIONS: Although outcomes are excellent for both sexes, females had greater need for targeted PH medical therapy in the long-term. Early reassessment and long-term follow-up of these patients are important. Further investigations into possible mechanisms to explain the differences are warranted.

Learning objectives for thoracic surgery: developing a national standard for undergraduate medical education.

BACKGROUND: The Continuing Professional Development (CPD) (Education) Committee of the Canadian Association of Thoracic Surgeons (CATS) has established a goal of describing the essential knowledge of thoracic surgery. We aimed to develop a national standardized set of undergraduate learning objectives for thoracic surgery. METHODS: We obtained these learning objectives from 4 medical schools in Canada. These 4 institutions were selected to provide a broad geographical representation of medical schools of varying sizes and of both official languages. The resulting list of learning objectives underwent critical review by the CPD (Education) Committee, made up of 5 Canadian community and academic thoracic surgeons, 1 thoracic surgery fellow and 2 general surgery residents. A national survey was developed and circulated to all CATS members (n = 209). Respondents were asked to indicate on a 5-point Likert scale whether each objective should be a priority for all medical students. RESULTS: Among 209 CATS members, 56 responded (response rate 27%). The mean length of experience in clinical practice among survey respondents was 10.6 (standard deviation 10.0) years. Respondents most commonly reported teaching or supervising medical students monthly (37.0%), followed by daily (29.6%). Eight of the 10 proposed objectives received a mean Likert score of 4/5 or higher and were selected for inclusion in the final list. A finalized list of 8 learning objectives was created, following a final review from the CATS Executive Committee. CONCLUSION: We developed a standardized set of learning objectives for medical students that was reflective of the core concepts within thoracic surgery.

Rapid Prototyping Techniques for the Development of a Take-Home Surgical Anastomosis Simulation Model.

OBJECTIVE: The objective of this paper is to describe the techniques and process of developing and testing a take-home surgical anastomosis simulation model. DESIGN: Through an iterative process, a simulation model was customized and designed to target specific skill development and performance objectives that focused on anastomotic techniques in thoracic surgery and consist of 3D printed and silicone molded components. Various manufacturing techniques such as silicone dip spin coating and injection molding have been described in this paper and explored as part of the research and development process. The final prototype is a low-cost, take-home model with reusable and replaceable components. SETTING: The study took place at a single-center quaternary care university-affiliated hospital. PARTICIPANTS: The participants included in the model testing were 10 senior thoracic surgery trainees who completed an in-person training session held during an annual hands- on thoracic surgery simulation course. Feedback was then collected in the form of an evaluation of the model from participants. RESULTS: All 10 participants had an opportunity to test the model and complete at least 1 pulmonary artery and bronchial anastomosis. The overall experience was rated highly, with minor feedback provided regarding the set- up and fidelity of the materials used for the anastomoses. Overall, the trainees agreed that the model was suitable for teaching advanced anastomotic techniques and expressed an interest in being able to use this model to practice skill development. CONCLUSIONS: Developed simulation model can be easily reduced, with customized components that accurately simulate real-life vascular and bronchial components suitable for training of anastomoses technique amongst senior thoracic surgery trainees.

Osteosarcoma emboli presenting as chronic thromboembolic pulmonary hypertension in a child.

A 13-year-old girl presented with hypoxemia during adjuvant chemotherapy for an osteosarcoma of the left distal femur. She underwent an amputation complicated by a post-operative pulmonary embolism (PE). Three months post-operatively, she was admitted to hospital with severe hypoxemia and diagnosed with pulmonary hypertension on echocardiogram in the context of extensive bilateral PE on computed tomography. She was planned for elective pulmonary thromboendarterectomy, but rapidly deteriorated requiring emergent surgery. At the time of surgery, she was found to have extensive tumor emboli throughout both pulmonary arteries. She recovered well post-operatively but died 2 months later from progressive disease.

Outcomes of lung transplantation from donors with a history of substance abuse.

OBJECTIVE: The study objective was to determine whether donor substance abuse (opioid overdose death, opioid use, cigarette or marijuana smoking) impacts lung acceptance and recipient outcomes. METHODS: Donor offers to a single center from 2013 to 2019 were reviewed to determine if lung acceptance rates and recipient outcomes were affected by donor substance abuse. RESULTS: There were 3515 donor offers over the study period. A total of 154 offers (4.4%) were opioid use and 117 (3.3%) were opioid overdose deaths. A total of 1744 donors (65.0%) smoked cigarettes and 69 donors (2.6%) smoked marijuana. Of smokers, 601 (35.0%) had less than 20 pack-year history and 1117 (65.0%) had more than 20 pack-year history. Substance abuse donors were younger (51.5 vs 55.2 P < .001), more often male (65.6 vs 54.8%, P < .001), more often White (86.2 vs 68.7%, P < .001), and had hepatitis C (8.3 vs 0.8%, P < .001). Donor acceptance was significantly associated with brain dead donors (odds ratio, 1.56, P < .001), donor smoking history (odds ratio, 0.56, P < .001), hepatitis C (odds ratio, 0.35, P < .001), younger age (odds ratio, 0.98, P < .001), male gender (odds ratio, 0.74, P = .004), and any substance abuse history (odds ratio, 0.50, P < .001), but not opioid use, opioid overdose death, or marijuana use. Recipient survival was equivalent when using lungs from donors who had opioid overdose death, who smoked marijuana, or who smoked cigarettes for less than 20 patient-years or more than 20 patient-years, and significantly longer in recipients of opioid use lungs. There was no significant difference in time to chronic lung allograft dysfunction for recipients who received lungs from opioid overdose death or with a history of opioid use, marijuana smoking, or cigarette smoking. CONCLUSIONS: Donor acceptance was impacted by cigarette smoking but not opioid use, opioid overdose death, or marijuana use. Graft outcomes and recipient survival were similar for recipients of lungs from donors who abused substances.

Influence of anterior tumor location on survival after resection of lung cancer invading the thoracic inlet (Pancoast tumors).

OBJECTIVE: Superior sulcus tumors are a challenging subset of non-small cell lung carcinomas invading the thoracic inlet. In this study, we determined whether the location of the tumor along the first rib had an influence on survival. METHODS: We performed a review of 92 consecutive patients undergoing surgery for non-small cell lung carcinomas invading the thoracic inlet between January 1996 and June 2021. Tumor location was categorized into anterior and posterior based on predefined zones. RESULTS: In total, 21 tumors were located anteriorly (23%) and 71 posteriorly (77%). The rate of R0 resection (81% vs 87%; P = .4) and pathological complete response to induction therapy (33% vs 37%; P = .8) were similar between locations. After a median follow-up of 5.8 years (range, 0.8-24 years), 49 patients died for an overall survival of 48% (95% CI, 38%-59%) at 5 years. The 5-year survival was favorably influenced by R0 (vs R1) resection (51% vs 29%; P = .02), pathological complete response (vs no pathological complete response) (69% vs 31%; P = .03), posterior (vs anterior) location (56% vs 22%; P = .01), and ≤60 (vs >60) years of age (61% vs 37%; P = .007). Compared with posterior tumors, anterior tumors were associated with higher risk of systemic recurrence and significantly greater survival benefit from pathological complete response. Anterior tumors remained an independent predictor of worse survival in multivariate analysis (hazard ratio, 2.3; 95% CI, 1.2-4.5; P = .01). CONCLUSIONS: The anatomical location of the tumor affects survival after resection of non-small cell lung carcinomas invading the thoracic inlet. Anterior tumors have greater propensity to metastasize and may derive greater benefit from optimal systemic therapy than posterior tumors.

Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension: A Systematic Review and Meta-analysis.

PURPOSE: To perform a systematic review and meta-analysis assessing the safety and efficacy of balloon pulmonary angioplasty (BPA) in the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). MATERIALS AND METHODS: Systematic literature searches were performed from inception to June 2022 to identify studies assessing BPA for CTEPH. Outcomes of interest included the following functional and hemodynamic measures: (a) six-minute walk distance (6MWD), (b) New York Heart Association (NYHA) status, (c) World Health Organization (WHO)-Functional Class status, (d) cardiac index (CI), (e) mean pulmonary artery pressure (mPAP), (f) mean right atrial pressure (mRAP), and (g) pulmonary vascular resistance (PVR). Subgroup analysis was also performed for BPA in post-pulmonary endarterectomy (PEA) patients. All reported BPA-related complications were also recorded. Forty unique studies with a total of 1763 patients were identified for meta-analysis. RESULTS: All functional and hemodynamic parameters improved significantly following BPA; 6MWD increased 70 m (95% CI 58-82; P < 0.001), NYHA class improved by - 0.9 classes (95% CI - 1.0 to - 0.8; P < 0.001), WHO-FC class improved by - 1 classes ((95% CI - 1.2 to - 0.9; P < 0.001), CI increased 0.26 L/min/m2 (95% CI 0.17-0.35; P < 0.001), mPAP decreased - 13.2 mmHg (95% CI - 14.7 to - 11.8; P < 0.001), mRAP decreased - 2.2 mmHg (95% CI - 2.8 to - 1.6; P < 0.001), and PVR decreased - 311 dyne/cm/s-5 (95% CI - 350 to - 271; P < 0.001). Meta-analysis of patients who underwent BPA for persistent pulmonary hypertension post-PEA demonstrated significant improvements in 6MWD, WHO-FC, PVR and mPAP. Most common complications included lung injury (8.16%), hemoptysis (7.07%) and vessel injury (5.05%). CONCLUSION: BPA represents a safe and effective treatment option for select individuals with CTEPH with significant improvements in hemodynamic parameters, improved exercise tolerance and a relatively low risk of major complications.

Ex vivo lung evaluation of single donor lungs when the contralateral lung is rejected increases safe use.

OBJECTIVE: The decision to perform a single-lung transplant (SLT) when the contralateral donor lung is rejected is a challenging scenario. The introduction of ex vivo lung perfusion (EVLP) has improved donor lung assessment, and we hypothesize that it has improved SLT outcomes in this setting. METHODS: A retrospective single-center review of all SLTs performed between 2000 and 2017 was performed in which the years 2000 to 2008 were considered the "pre-EVLP era" and 2009 to 2017 the "EVLP era." Recipients of SLT lungs when the contralateral lung was declined were classified into 3 groups: (1) Pre-EVLP era, (2a) EVLP era but EVLP not used, and (2b) EVLP era and EVLP used. The outcomes of interest were survival, time-to-extubation, and intensive care unit and hospital stay. RESULTS: Among 1692 transplants between 2000 and 2017, 244 (14%) were SLT. SLT rate was similar between eras (pre-EVLP 16% vs EVLP 15%), but more SLTs were performed where the contralateral lung was declined in the EVLP era (pre-EVLP 32% vs EVLP 45%, P = .04). Lungs evaluated on EVLP had lower procurement partial pressure of oxygen and were more often from donation after cardiac death donors. Recipients were generally also sicker, with a greater proportion of rapidly deteriorating recipients. Despite this, outcomes were similar between eras with a trend towards lower 30-day mortality in the EVLP era. CONCLUSIONS: The availability of EVLP allowed for better evaluation of marginal single lungs when the contralateral was declined. This has led to increased use rates with preserved outcomes despite use of more extended criteria organs.

Extension of Cold Static Donor Lung Preservation at 10°C.

Cold Static Donor Lung Preservation at 10°CDonor lungs for transplantation are currently stored on ice and transplanted as rapidly as possible. In an advance that may ease transplant logistics, Ali et al. report that prolonged storage at 10°C may lead to equivalent outcomes.

ISHLT consensus statement: Perioperative management of patients with pulmonary hypertension and right heart failure undergoing surgery.

Pulmonary hypertension (PH) is a risk factor for morbidity and mortality in patients undergoing surgery and anesthesia. This document represents the first international consensus statement for the perioperative management of patients with pulmonary hypertension and right heart failure. It includes recommendations for managing patients with PH being considered for surgery, including preoperative risk assessment, planning, intra- and postoperative monitoring and management strategies that can improve outcomes in this vulnerable population. This is a comprehensive document that includes common perioperative patient populations and surgical procedures with unique considerations.

Plasma-first: accelerating lung cancer diagnosis and molecular profiling through liquid biopsy.

Introduction: Molecular profiling of tumor tissue is the gold standard for treatment decision-making in advanced non-small cell lung cancer (NSCLC). Results may be delayed or unavailable due to insufficient tissue, prolonged wait times for biopsy, pathology assessment and testing. We piloted the use of plasma testing in the initial diagnostic workup for patients with suspected advanced lung cancer. Methods: Patients with ⩽15 pack-year smoking history and suspected advanced lung cancer referred to the lung cancer rapid diagnostic program underwent plasma circulating-tumor DNA testing using a DNA-based mutation panel. Tissue testing was performed per standard of care, including comprehensive next-generation sequencing (NGS). The primary endpoint was time from diagnostic program referral to cancer treatment in stage IV NSCLC patients (Cohort A) compared to a contemporary cohort not enrolled in the study (Cohort B) and an historical pre-COVID cohort referred to the program between 2018 and 2019 (Cohort C). Results: From January to June 2021, 20 patients were enrolled in Cohort A; median age was 70.5 years (range 33-87), 70% were female, 55% Caucasian, 85% never smokers, and 75% were diagnosed with NSCLC. Seven had actionable alterations detected in plasma or tissue (4/7 concordant). Fusions, not tested in plasma, were identified by immunohistochemistry for three patients. Mean result turnaround time was 17.8 days for plasma NGS and 23.6 days for tissue (p = 0.10). Mean time from referral to treatment initiation was significantly shorter in cohort A at 32.6 days (SD 13.1) versus 62.2 days (SD 31.2) in cohort B and 61.5 days (SD 29.1) in cohort C, both p < 0.0001. Conclusion: Liquid biopsy in the initial diagnostic workup of patients with suspected advanced NSCLC can lead to faster molecular results and shorten time to treatment even with smaller DNA panels. An expansion study using comprehensive NGS plasma testing with faster turnaround time is ongoing (NCT04862924).

Right-to-left ventricle ratio determined by machine learning algorithms on CT pulmonary angiography images predicts prolonged ICU length of stay in operated chronic thromboembolic pulmonary hypertension.

OBJECTIVE: Right-to-left ventricle diameter ratio (dRV/dLV) on CT pulmonary angiography (CTPA) is a predictor of outcomes in non-operated chronic thromboembolic pulmonary hypertension (CTEPH) patients. The purpose of this study is to evaluate the performance of a novel machine learning (ML) algorithm for dRV/dLV measurement in operated CTEPH patients and its association with post-operative outcomes. METHODS: This retrospective study reviewed consecutive CTEPH patients who underwent pulmonary endarterectomy between 2013 and 2017. ML calculated dRV/dLV on pre-operative CTPA and compared with manual measures. Associations of dRV/dLV with patient characteristics and post-operative outcomes were evaluated including intensive care (ICU) and hospital length of stay (LOS) using multivariable linear regression analysis. Prolonged LOS was defined as greater than median. RESULTS: ML segmented the ventricles in 99/125 (79%) patients. The most common cause of failure was misidentification of the moderator band as the interventricular septum (7.9%). Mean dRV/dLV by ML was 1.4 ± 0.4 and strongly correlated with manual measures (r = 0.9-0.96 p < 0.0001). dRV/dLV was moderately correlated with measures of pulmonary hypertension on right heart catheterization and RV dilatation on echocardiogram (r = 0.5-0.6, p < 0.0001). dRV/dLV ≥ 1.2 was associated with proximal Jamieson type disease (p = 0.032), longer cardiopulmonary bypass (p = 0.037), aortic cross-clamp (p = 0.022) and circulatory arrest (p < 0.001) at surgery and dRV/dLV ≥ 1.6 with post-operative ECMO (p = 0.006). dRV/dLV was independently associated with prolonged ICU LOS (OR = 3.79, 95% CI 1.1-13.06, p = 0.035). CONCLUSION: dRV/dLV was associated with CTEPH severity and independently associated with prolonged ICU LOS. This CT parameter may therefore assist in perioperative planning. Further refinement of the ML algorithm or CTPA technique is required to avoid errors in ventricular segmentation. ADVANCES IN KNOWLEDGE: Automated right-to-left ventricle ratio measurement by machine learning is feasible and is independently associated with outcome after pulmonary endarterectomy.