Cardiac Risk Stratification in Liver Transplantation: Results of a Tiered Assessment Protocol Based on Traditional Cardiovascular Risk Factors

Enhancing pre-transplant cardiac assessment: Validation and utility of the CAD-LT score with CCTA in liver transplant candidates

BACKGROUND

Coronary computed tomography angiography (CCTA) is increasingly being used in the preoperative workup for liver transplantation (LT). We sought to assess the utility of integrating CCTA with the novel CAD-LT (Coronary Artery Disease in Liver Transplantation) score and its impact on reducing the need for invasive coronary angiography prior to LT.

METHODS

We conducted a retrospective cohort study of consecutive patients (age ≥ 18 years) who underwent CCTA for LT workup between 2011 and 2018 at the Victorian Liver Transplant Unit, Melbourne, Australia. CAD-LT scores, a traditional risk factor-based criteria, were calculated, and patients stratified as low-, intermediate- or high-risk.

RESULTS

Overall, 229 patients underwent CCTA. The mean age was 66 ± 5 years (82% male) with a modest-to-high risk factor burden (diabetes, 53%; hypertension, 46%; current or former smoker, 62%). The mean CAD-LT score of our cohort was 12.4 ± 4.0. No patients were classified as low-risk, 49 patients (21.4%) were deemed intermediate-risk and 180 patients (78.6%) were deemed high-risk. A high CAD-LT score (≥ 9) showed high sensitivity (95.3% [95% CI 86-98%]) and modest specificity (27.8% [95% CI 21-35%]) for the detection of obstructive coronary artery disease on CCTA, with a negative predictive value of 94%. Following multidisciplinary discussions, only 41 patients (18%) of patients proceeded to ICA of which 27% received percutaneous coronary intervention.

CONCLUSIONS

The use of CCTA in patients deemed intermediate- to high-risk by the CAD-LT score has the potential to reduce the need for invasive coronary angiography in patients undergoing LT workup.

Predicting major adverse cardiovascular events after orthotopic liver transplantation using a supervised machine learning model: A cohort study

BACKGROUND

Liver transplant (LT) patients have become older and sicker. The rate of post-LT major adverse cardiovascular events (MACE) has increased, and this in turn raises 30-d post-LT mortality. Noninvasive cardiac stress testing loses accuracy when applied to pre-LT cirrhotic patients.

AIM

To assess the feasibility and accuracy of a machine learning model used to predict post-LT MACE in a regional cohort.

METHODS

This retrospective cohort study involved 575 LT patients from a Southern Brazilian academic center. We developed a predictive model for post-LT MACE (defined as a composite outcome of stroke, new-onset heart failure, severe arrhythmia, and myocardial infarction) using the extreme gradient boosting (XGBoost) machine learning model. We addressed missing data (below 20%) for relevant variables using the k-nearest neighbor imputation method, calculating the mean from the ten nearest neighbors for each case. The modeling dataset included 83 features, encompassing patient and laboratory data, cirrhosis complications, and pre-LT cardiac assessments. Model performance was assessed using the area under the receiver operating characteristic curve (AUROC). We also employed Shapley additive explanations (SHAP) to interpret feature impacts. The dataset was split into training (75%) and testing (25%) sets. Calibration was evaluated using the Brier score. We followed Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis guidelines for reporting. Scikit-learn and SHAP in Python 3 were used for all analyses. The supplementary material includes code for model development and a user-friendly online MACE prediction calculator.

RESULTS

Of the 537 included patients, 23 (4.46%) developed in-hospital MACE, with a mean age at transplantation of 52.9 years. The majority, 66.1%, were male. The XGBoost model achieved an impressive AUROC of 0.89 during the training stage. This model exhibited accuracy, precision, recall, and F1-score values of 0.84, 0.85, 0.80, and 0.79, respectively. Calibration, as assessed by the Brier score, indicated excellent model calibration with a score of 0.07. Furthermore, SHAP values highlighted the significance of certain variables in predicting postoperative MACE, with negative noninvasive cardiac stress testing, use of nonselective beta-blockers, direct bilirubin levels, blood type O, and dynamic alterations on myocardial perfusion scintigraphy being the most influential factors at the cohort-wide level. These results highlight the predictive capability of our XGBoost model in assessing the risk of post-LT MACE, making it a valuable tool for clinical practice.

CONCLUSION

Our study successfully assessed the feasibility and accuracy of the XGBoost machine learning model in predicting post-LT MACE, using both cardiovascular and hepatic variables. The model demonstrated impressive performance, aligning with literature findings, and exhibited excellent calibration. Notably, our cautious approach to prevent overfitting and data leakage suggests the stability of results when applied to prospective data, reinforcing the model's value as a reliable tool for predicting post-LT MACE in clinical practice.

Atherosclerosis on CT coronary angiography and the risk of long-term cardiovascular events after liver transplantation

Computed tomography coronary angiography (CTCA) is increasingly utilized for preoperative risk stratification before liver transplantation (LT). We sought to assess the predictors of advanced atherosclerosis on CTCA using the recently developed Coronary Artery Disease-Reporting and Data System (CAD-RADS) score and its impact on the prediction of long-term major adverse cardiovascular events (MACE) following LT. We conducted a retrospective cohort study of consecutive patients who underwent CTCA for LT work-up between 2011 and 2018. Advanced atherosclerosis was defined as coronary artery calcium scores > 400 or CAD-RADS score ≥ 3 (≥50% coronary artery stenosis). MACE was defined as myocardial infarction, heart failure, stroke, or resuscitated cardiac arrest. Overall, 229 patients underwent CTCA (mean age 66 ± 5 y, 82% male). Of these, 157 (68.5%) proceeded with LT. The leading etiology of cirrhosis was hepatitis (47%), and 53% of patients had diabetes before transplant. On adjusted analysis, male sex (OR 4.6, 95% CI 1.5-13.8, p = 0.006), diabetes (OR 2.2, 95% CI 1.2-4.2, p = 0.01) and dyslipidemia (OR 3.1, 95% CI 1.3-6.9, p = 0.005) were predictors of advanced atherosclerosis on CTCA. Thirty-two patients (20%) experienced MACE. At a median follow-up of 4 years, CAD-RADS ≥ 3, but not coronary artery calcium scores, was associated with a heightened risk of MACE (HR 5.8, 95% CI 1.6-20.6, p = 0.006). Based on CTCA results, 71 patients (31%) commenced statin therapy which was associated with a lower risk of all-cause mortality (HR 0.48, 95% CI 0.24-0.97, p = 0.04). The standardized CAD-RADS classification on CTCA predicted the occurrence of cardiovascular outcomes following LT, with a potential to increase the utilization of preventive cardiovascular therapies.

Screening Modalities for Coronary Artery Disease in Liver Transplant Candidates: A Review of the Literature

Patients with cirrhosis undergoing liver transplant (LT) are at high risk of postoperative cardiopulmonary complications. It is known that patients with coronary artery disease (CAD) have greater rates of post-LT morbidity and mortality than patients without CAD. Thus, identifying significant CAD in LT candidates is of the utmost importance to optimize survival posttransplant. Consensus is lacking on the ideal screening test for CAD in LT candidates. Traditional exercise and many pharmacologic stress tests are impractical and inaccurate in patients with cirrhosis due to their unique physiology. The purpose of this review is to describe different screening modalities for CAD among LT candidates. The background, diagnostic accuracy, and limitations of each screening modality are described to achieve this goal.

A 7-month-old girl with a suspected air embolism complication during a living-donor liver transplantation procedure: a case report

Background

Pediatric liver transplantation is an important modality for treating biliary atresia. The overall survival rate of pediatric liver transplantation has significantly improved. The incidence of perioperative cardiac events was evaluated, and risk factors were also investigated in adult patients undergoing liver transplantation in previous studies. To the best of our knowledge, this is the first case of a cardiac event during a pediatric living-donor liver transplantation.

Case summary

Our report describes the management of cardiac events during a liver transplantation in a 7-month-old girl. The ST segment began to increase to 3.0 mm immediately after reperfusion, with peak ST-segment elevation reaching 13.2 mm after 45 min. The procedure ended uneventfully after continuous symptomatic and etiological treatment. It was considered to be the occurrence of an acute air embolism complication during the procedure based on the electrocardiograph and biomarkers. An echocardiogram during follow-up showed a patent foramen ovale with a left-to-right shunt tract width of 2.7 mm.

Discussion

Pediatric liver transplantation has become a state-of-the-art treatment for children with end-stage liver disease and can improve the quality of life to some extent. These children may be complicated with congenital heart disease, which increases the risk of surgery. Application of echocardiogram, close monitoring, and appropriate management may reduce the incidence of perioperative cardiac events.

Evaluation of recipients with significant comorbidity - Patients with cardiovascular disease

Liver transplant(ation) (LT) is the most effective treatment for patients with decompensated liver disease. The increasing prevalence of obesity and type 2 diabetes and the growing number of patients with non-alcoholic fatty liver disease being evaluated for LT, have resulted in a greater proportion of LT candidates presenting with a higher risk of cardiovascular disease. As cardiovascular disease is a major cause of morbidity and mortality after LT, a thorough cardiovascular evaluation pre-LT is crucial. In this review, we discuss the latest evidence on the cardiovascular evaluation of LT candidates and we focus on the most prevalent conditions, namely ischaemic heart disease, atrial fibrillation and other arrhythmias, valvular heart disease, and cardiomyopathies. LT candidates undergo an electrocardiogram, a resting transthoracic echocardiography and an assessment of their cardiopulmonary functional ability as part of their standardised pre-LT work-up. Further diagnostic work-up is undertaken based on the results of the baseline evaluation and may include a coronary computed tomography angiography in patients with cardiovascular risk factors. The evaluation of potential LT candidates for cardiovascular disease requires a multidisciplinary approach, with input from anaesthetists, cardiologists, hepatologists and transplant surgeons.

Acute coronary syndrome after liver transplantation in a young primary biliary cholangitis recipient with dyslipidemia: a case report

Background

Primary biliary cholangitis (PBC) is a chronic, progressive liver disease associated with dyslipidemia. There is a consensus that PBC does not accelerate coronary artery disease despite high cholesterol levels, so the screening test for the coronary artery is not routinely performed before liver transplantation (LT). To date, no report has described the potential risk of PBC-related dyslipidemia for developing acute coronary syndrome (ACS) after LT.

Case presentation

A 40-year-old Asian female with a known history of PBC underwent ABO-incompatible living-donor LT, with her husband as the donor. Although she had high cholesterol and triglyceride levels that were refractory to medications, she passed all routine preoperative examinations, including cardiopulmonary function tests and infection screenings. One week after LT, she developed ACS with 90% stenosis of both the left anterior descending artery and left circumflex artery. Emergent stent implantation was successfully performed followed by dual antiplatelet therapy. The long history of PBC and associated severe dyslipidemia for 10 years would have accelerated the atherosclerosis, causing latent stenosis in the coronary artery. Inapparent stenosis might have become apparent due to unstable hemodynamics during the acute phase after LT.

Conclusions

PBC-related dyslipidemia potentially brings a risk for developing ACS after LT. This experience suggests that the preoperative evaluation of the coronary artery should be considered for high-risk patients, especially those who have drug-resistant dyslipidemia.

Emerging Evidence on Coronary Heart Disease Screening in Kidney and Liver Transplantation Candidates: A Scientific Statement From the American Heart Association: Endorsed by the American Society of Transplantation

Coronary heart disease is an important source of mortality and morbidity among kidney transplantation and liver transplantation candidates and recipients and is driven by traditional and nontraditional risk factors related to end-stage organ disease. In this scientific statement, we review evidence from the past decade related to coronary heart disease screening and management for kidney and liver transplantation candidates. Coronary heart disease screening in asymptomatic kidney and liver transplantation candidates has not been demonstrated to improve outcomes but is common in practice. Risk stratification algorithms based on the presence or absence of clinical risk factors and physical performance have been proposed, but a high proportion of candidates still meet criteria for screening tests. We suggest new approaches to pretransplantation evaluation grounded on the presence or absence of known coronary heart disease and cardiac symptoms and emphasize multidisciplinary engagement, including involvement of a dedicated cardiologist. Noninvasive functional screening methods such as stress echocardiography and myocardial perfusion scintigraphy have limited accuracy, and newer noninvasive modalities, especially cardiac computed tomography-based tests, are promising alternatives. Emerging evidence such as results of the 2020 International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease trial emphasizes the vital importance of guideline-directed medical therapy in managing diagnosed coronary heart disease and further questions the value of revascularization among asymptomatic kidney transplantation candidates. Optimizing strategies to disseminate and implement best practices for medical management in the broader end-stage organ disease population should be prioritized to improve cardiovascular outcomes in these populations.

A systematic review and meta-analysis on the impact of pre-existing and new-onset atrial fibrillation on outcomes before and after liver transplantation

BACKGROUND AND AIMS

Atrial Fibrillation (AF) is the most commonly diagnosed cardiac arrhythmia. It is associated with significant morbidity and mortality, as it is a major risk factor for cerebral vascular accidents (CVA). Our aim was to determine the prevalence of pre-existing and new-onset AF among patients undergoing liver transplantation (LT) and its impact on post-transplant outcomes.

METHODS

Medline and Embase were searched. Single-arm analysis was conducted using the generalized linear mixed model to determine the prevalence of pre-existing and new-onset AF. Logistic regression was performed to analyze risk factors. Comparative meta-analysis in odds ratio was conducted for binary outcomes.

RESULTS

Twenty articles were included, with 17 studies on pre-existing AF, and 7 including data on new-onset AF post-LT. The prevalence of pre-existing AF was 3.3% (CI 2.3-4.7) (14 studies, 45,070 patients) in pooled analysis. Significantly higher prevalence of pre-existing AF patients from North America was noted when compared to Europe (4.5%, CI 3.4-5.8 vs 1.5%, CI 0.8-2.7; p = 0.001). Body mass index (BMI), history of hypertension, diabetes, coronary artery disease (CAD), and cerebrovascular accidents (CVA) were risk factors for pre-existing AF. Pre-existing AF was significantly associated with major adverse cardiac or cerebrovascular events (MACCE) postoperatively (OR 8.02, 95%CI 5.40-11.90, p < 0.001). New-onset AF post-LT had an incidence of 6.8% (CI 4.9-9.3), and was associated with increased risk of mortality (OR 2.31, 95% CI 1.76-3.02, p < 0.001) and graft failure (OR 2.98, CI 1.99-4.47, p < 0.001).

CONCLUSION

AF is relatively more common among patients undergoing LT compared to the general non-transplant population. Additionally, it is associated with adverse outcomes including MACCE, thus warranting clinical attention. Thorough cardiac assessment, and close surveillance of post-operative AF may be clinically prudent.

Impact of cardiac dysfunction on morbidity and mortality in liver transplant candidates

The prognostic role of cardiac dysfunction in cirrhotic patients is increasingly recognised. We studied its impact on morbidity and mortality before and after liver transplantation (LT) including development of post-transplant cardiovascular disease (CVD). In this retrospective study, cirrhotic patients who underwent LT assessment from January 2010 to December 2020 were reviewed. Demographics, cardiac investigations and clinical course were analysed to identify prevalence of cardiac dysfunction and its role in LT outcomes. Survival analysis was performed using Cox proportional hazard regression modelling, with LT as a time-varying covariate and as an interaction variable with cardiac dysfunction. 308 patients (70% male) were studied. The median (interquartile range) age at LT assessment was 56 (12) years. Cardiac dysfunction was found in 178 (58%) patients (diastolic, 169; systolic, 26; both, 17) and was significantly associated with hepatorenal syndrome/acute kidney injury and peri- and post-transplant morbidity (adjusted odds ratio [aOR] 1.94, 95%CI 1.06-3.52, p < 0.001; aOR 2.01, 95%CI 1.06-3.82, p = 0.033; aOR 1.9, 95%CI 1.01-3.65, p = 0.023, respectively). Cardiac dysfunction was not associated with mortality before (adjusted hazard ratio [aHR] 1.01, 95% CI 0.99-1.01) or after LT (aHR 0.74, 95% CI 0.4-1.05. Post-transplant CVD (61% cardiac failure) occurred in 36 patients and there was no significant association with cardiac dysfunction (p = 0.11). Cardiac dysfunction was common in LT candidates and was significantly associated with morbidity before and after LT. Studies on the role of advanced echocardiographic parameters to improve diagnosis of cardiac dysfunction and optimise LT outcomes are needed. This article is protected by copyright. All rights reserved.

Preoperative evaluation of geriatric patients undergoing liver transplantation

PURPOSE OF REVIEW

As the population of the world is aging the number of geriatric patients undergoing liver transplantation (LT) is also increasing. They pose a unique challenge for the caregivers, as they have age-related physiological changes, multiple comorbidities and cirrhosis-related pathologies.

RECENT FINDINGS

Twenty-two percent of patients who undergo LT are older than 65 years. Many patients suffer from nonalcoholic steatohepatitis (NASH), hepatocellular carcinoma and hepatitis-C virus. Incidence of NASH tends to increase with age, obesity, diabetes and metabolic syndrome. Elderly patients require comprehensive cognitive, cardiac and pulmonary evaluation prior to LT. Cirrhotic cardiomyopathy, hepatopulmonary syndrome, portopulmonary hypertension and frailty are of specific concern.

SUMMARY

Proportion of elderly patients who are undergoing LT continues to increase. These patients require comprehensive cardiopulmonary and frailty evaluation. Consensus-based practice advisories need to be developed to standardize preoperative evaluation of geriatric patients awaiting LT.