Prediction of Perioperative Cardiovascular Events in Liver Transplantation

Minimizing Metabolic and Cardiac Risk Factors to Maximize Outcomes After Liver Transplantation

Cardiovascular disease (CVD) is a leading complication after liver transplantation and has a significant impact on patients' outcomes posttransplant. The major risk factors for post-liver transplant CVD are age, preexisting CVD, nonalcoholic fatty liver disease, chronic kidney disease, and metabolic syndrome. This review explores the contemporary strategies and approaches to minimizing cardiometabolic disease burden in liver transplant recipients. We highlight areas for potential intervention to reduce the mortality of patients with metabolic syndrome and CVD after liver transplantation.

Deep Learning-Based Prediction Modeling of Major Adverse Cardiovascular Events After Liver Transplantation

Objective

To validate deep learning models' ability to predict post-transplantation major adverse cardiovascular events (MACE) in patients undergoing liver transplantation (LT).

Patients and Methods

We used data from Optum's de-identified Clinformatics Data Mart Database to identify liver transplant recipients between January 2007 and March 2020. To predict post-transplantation MACE risk, we considered patients' demographics characteristics, diagnoses, medications, and procedural data recorded back to 3 years before the LT procedure date (index date). MACE is predicted using the bidirectional gated recurrent units (BiGRU) deep learning model in different prediction interval lengths up to 5 years after the index date. In total, 18,304 liver transplant recipients (mean age, 57.4 years [SD, 12.76]; 7158 [39.1%] women) were used to develop and test the deep learning model's performance against other baseline machine learning models. Models were optimized using 5-fold cross-validation on 80% of the cohort, and model performance was evaluated on the remaining 20% using the area under the receiver operating characteristic curve (AUC-ROC) and the area under the precision-recall curve (AUC-PR).

Results

Using different prediction intervals after the index date, the top-performing model was the deep learning model, BiGRU, and achieved an AUC-ROC of 0.841 (95% CI, 0.822-0.862) and AUC-PR of 0.578 (95% CI, 0.537-0.621) for a 30-day prediction interval after LT.

Conclusion

Using longitudinal claims data, deep learning models can efficiently predict MACE after LT, assisting clinicians in identifying high-risk candidates for further risk stratification or other management strategies to improve transplant outcomes based on important features identified by the model.

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.

Management of the liver transplant candidate with high cardiac risk: Multidisciplinary best practices and recommendations

In a setting characterized by a growing prevalence of patients with alcohol-associated and metabolic dysfunction-associated steatotic liver diseases, coupled with an aging patient demographic, the incidence of cardiac comorbidities in liver transplant candidates is on the rise. These comorbidities not only pose barriers to transplant eligibility but also impact the intraoperative course and affect posttransplant outcomes. As such, there is a significant need to optimize the clinical management of these cardiac comorbidities. However, there is a scarcity of evidence regarding the best practices for managing cardiac comorbidities such as coronary and valvular heart diseases, arrhythmia, and cardiomyopathy in this population, both before and during transplant surgery. These conditions necessitate a coordinated and multidisciplinary approach to care. In this manuscript, we conduct a comprehensive review of the most recent evidence pertaining to the preoperative and intraoperative management of these cardiac comorbidities in liver transplant candidates. Our aim is to provide recommendations that improve and standardize their clinical care.

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.

Evolution of pretransplant cardiac risk factor burden and major adverse cardiovascular events in liver transplant recipients over time

Major adverse cardiovascular events (MACEs) are the leading cause of early (<1 y) complications after liver transplantation (LT). NASH, the leading indication for waitlisting for LT, is associated with high cardiac risk factor burden. The contemporary prevalence and temporal trends in pretransplant cardiac risk factor burden and post-LT MACE among LT recipients (LTRs) with and without NASH are unknown. The aim of this study was to evaluate (1) the evolution of post-LT cardiac risk factors in LTRs over time and (2) post-LT MACE over time, stratified by NASH status. This is a retrospective cohort of 1775 adult LTRs at a single transplant center (2003-2020). MACE was defined as death or hospitalization from myocardial infarction, revascularization, stroke, heart failure during the first post-LT year. Between 2003 and 2020, there was a significant increase in pre-LT NASH ( ptrend <0.05). There was also a significant increase in pre-LT obesity, atherosclerotic cardiovascular (CV) disease, and older age (≥65 y old) ( ptrend <0.05 for all). There was no significant change in the proportion of LTRs with diabetes, chronic kidney disease, or heart failure. Unexpectedly, there were no changes in the rate of post-LT MACE over the study period (-0.1% per year, ptrend =0.44). The lack of change in MACE despite an increase in CV risk factor prevalence may reflect advancement in the identification and management of CV risk factors in LTRs. With projected continued increase in cardiac risk burden and the proportion of patients transplanted for NASH, it is critical for LT programs to develop and implement quality improvement efforts to optimize CV care in LTRs.

Management of cardiac diseases in liver transplant recipients: Comprehensive review and multidisciplinary practice-based recommendations

Cardiac diseases are one of the most common causes of morbidity and mortality following liver transplantation (LT). Prior studies have shown that cardiac diseases affect close to one-third of liver transplant recipients (LTRs) long term and that their incidence has been on the rise. This rise is expected to continue as more patients with advanced age and/or non-alcoholic steatohepatitis undergo LT. In view of the increasing disease burden, a multidisciplinary initiative was developed to critically review the existing literature (between January 1, 1990 and March 17, 2021) surrounding epidemiology, risk assessment, and risk mitigation of coronary heart disease, arrhythmia, heart failure, and valvular heart disease and formulate practice-based recommendations accordingly. In this review, the expert panel emphasizes the importance of optimizing management of metabolic syndrome and its components in LTRs and highlights the cardioprotective potential for the newer diabetes medications (e.g., sodium glucose transporter-2 inhibitors) in this high-risk population. Tailoring the multidisciplinary management of cardiac diseases in LTRs to the cardiometabolic risk profile of the individual patient is critical. The review also outlines numerous knowledge gaps to pave the road for future research in this sphere with the ultimate goal of improving clinical outcomes.

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

Coronary artery disease (CAD) confers increased perioperative risk in patients undergoing liver transplantation (LT). Although routine screening for CAD is recommended, there are limited data on the effectiveness of screening strategies. We evaluated the safety and efficacy of a 3-tiered cardiac risk-assessment protocol that stratifies patients based on age and traditional cardiac risk factors. We peformed a single-center, prospective, observational study of consecutive adult patients undergoing LT assessment (2010-2017). Patients were stratified into low-risk (LR), intermediate-risk (IR), or high-risk (HR) cardiac groups and received standardized investigations with selective use of transthoracic echocardiography (TTE), dobutamine stress echocardiography (DSE), computed tomography coronary angiography (CTCA), and coronary angiography (CA). Primary outcomes were cardiac events (CEs) and cardiovascular death up to 30 days after LT. Overall, 569 patients were included, with 76 patients identified as LR, 256 as IR, and 237 as HR. Cardiac risk factors included diabetes mellitus (26.0%), smoking history (47.3%), hypertension (17.8%), hypercholesterolemia (7.2%), family (17.0%) or prior history of heart disease (6.0%), and obesity (27.6%). Of the patients, 42.0% had ≥2 risk factors. Overall compliance with the protocol was 90.3%. Abnormal findings on TTE, DSE, and CTCA were documented in 3, 23, and 44 patients, respectively, and 12 patients were not listed for transplantation following cardiac assessment (1 LR, 2 IR, and 9 HR). Moderate or severe CAD was identified in 25.4% of HR patients on CTCA following a normal DSE. CEs were recorded in 7 patients (1.2%), with 2 cardiovascular deaths (0.4%). Cardiac risk stratification based on traditional cardiac risk factors with the selective use of DSE, CTCA, and CA is a safe and feasible approach that results in a low perioperative cardiac event rate.

Cardiac Risk Assessment in Liver Transplant Candidates: Current Controversies and Future Directions

In the changing landscape of liver transplantation (LT), we are now evaluating older and sicker patients with more cardiovascular comorbidities, and the spectrum of cardiovascular disease is uniquely physiologically impacted by end-stage liver disease. Cardiac complications are now the leading cause of morbidity and mortality in LT recipients, and the pretransplant risk is exacerbated immediately during the transplant operation and continues long term under the umbrella of immunosuppression. Accurate risk estimation of cardiac complications before LT is paramount to guide allocation of limited health care resources and to improve both short-term and long-term clinical outcomes for patients. Current screening and diagnostic testing are limited in their capacity to accurately identify early coronary disease and myocardial dysfunction in persons with end-stage liver disease physiology. Furthermore, a number of testing modalities have not been evaluated in patients with end-stage liver disease. As a result, there is wide variation in cardiac risk assessment practices across transplant centers. In this review, we propose a definition for defining cardiac events in LT, evaluate the current evidence for surgery-related, short-term and long-term cardiac risk assessment in LT candidates, propose an evidence-based testing algorithm, and highlight specific gaps in knowledge and current controversies, identifying areas for future research.

Relationship between QT interval prolongation and structural abnormalities in cirrhotic cardiomyopathy: A change in the current paradigm

It is postulated that cardiac structural abnormalities observed in cirrhotic cardiomyopathy (CCM) contribute to the electrophysiologic abnormality of QT interval (QTc) prolongation. We sought to evaluate whether QTc prolongation is associated with intrinsic abnormalities in cardiac structure and function that characterize CCM. Consecutive patients undergoing liver transplant work-up between 2010 and 2018 were included. Measures of cardiac function on stress testing including cardiac reserve and chronotropic incompetence were collected prospectively and a corrected QTc ≥ 440 ms was considered prolonged. Overall, 439 patients were included and 65.1% had a prolonged QTc. There were no differences in markers of left ventricular and atrial remodeling, or resting systolic and diastolic function across QTc groups. The proportion of patients that met the criteria for a low cardiac reserve (39.2 vs 36.6%, p = .66) or chronotropic incompetence (18.1 vs 21.3%, p = .52) was not different in those with a QTc ≥ 440 vs <440 ms. Further, there was no association between QTc prolongation and CCM by either the 2005 World College of Gastroenterology or modified 2020 Cirrhotic Cardiomyopathy Consortium criteria. QT interval prolongation was not associated with structural or functional cardiac abnormalities that characterize CCM. These findings suggest that CCM and QT interval prolongation in cirrhosis may be two separate entities with distinct pathophysiological origins.

Sudden cardiac death following liver transplantation: Incidence, trends and risk predictors

BACKGROUND

Cardiovascular events are a leading cause of mortality following liver transplantation (LT). Although a preponderance of sudden cardiac death (SCD) in this population has been reported, there is a paucity of data evaluating the incidence, timing and predictors of SCD following LT.

METHODS

Using the prospectively collected Australian and New Zealand Liver Transplant Registry, a cohort study of all adult LTs from 1985 to 2017 was performed to ascertain the incidence and predictors of SCD. Recipient cause of death was adjudicated by an interdisciplinary panel.

RESULTS

4265 LT patients were followed-up for 37,409 person-years. SCD was the leading mode of cardiovascular death with an incidence rate of 165 per 100,000 person-years. There was a significant increase in the hazard of SCD in the contemporary (1996-2017) vs early era (1985-1995) (hazard ratio [HR] 2.42, 95%CI 1.10-5.40; p = 0.02). On Cox regression after adjusting for significant univariate predictors including age, coronary artery disease and non-alcoholic steatohepatitis, pre-transplant diabetes was the only independent predictor of SCD (HR 2.5 95%CI 1.1-6.0).

CONCLUSION

SCD is the leading mode of cardiovascular cause-specific mortality following LT and diabetes was associated with a two-fold higher risk for its occurrence. Given the escalating cardiovascular risk factor profile of LT candidates, targeted therapies especially in patients with diabetes are needed to mitigate risk of post-transplant SCD.

Effect of liver transplantation on QT-interval prolongation and impact on mortality

BACKGROUND

QT-interval prolongation is considered the electrophysiological hallmark of cirrhotic cardiomyopathy. However, the significance of QT-interval prolongation and how it is affected by liver transplantation (LT) remains unclear.

METHODS

Consecutive inpatients undergoing LT between 2010 and 2017 at a state-wide liver transplant center in Australia were included. Preoperative, early postoperative and long-term follow-up corrected QT-intervals (QTc) were manually measured by a cardiologist. QTc was calculated using the Bazett formula and QTc ≥440 milliseconds (ms) was considered prolonged.

RESULTS

Overall, 1111 ECG tracings among 408 patients (mean age 57 ± 12 years) were assessed. Pre-LT, 265 patients (65.0%) had QTc ≥440 ms and 24 patients (5.9%) had QTc ≥500 ms. In the early postoperative period, there was a significant increase in QTc compared to pre-LT (471 ± 39 vs. 452 ± 31 ms, p < 0.001) and 80 patients (20.3%) had QTc ≥500 ms. At a median of six months post-LT, there was significant reduction in mean QTc compared to pre-LT (430 ± 32 vs. 452 ± 31 ms; p < 0.001) with the QTc shortening in 73% of patients. QT-interval prolongation was not associated with postoperative complications or mortality at any time-point.

CONCLUSION

QT-interval prolongation is common in patients with liver cirrhosis and this metric normalized in the majority within six months post-LT. A significant increase in QTc was noted early post-LT, with over 20% demonstrating QTc ≥500 ms. QT-interval prolongation was not associated with post-transplant complications or mortality. Resolution of QT-interval prolongation suggests that this feature of cirrhotic cardiomyopathy may reverse post-transplantation.

Clinical Presentation, Treatment, and Mortality Rate in Liver Transplant Recipients With Coronavirus Disease 2019: A Systematic Review and Quantitative Analysis

Liver transplant recipients may be at increased risk for adverse outcomes with coronavirus disease 2019 (COVID-19) infection because of chronic immunosuppression and associated comorbidities. There is a paucity of literature describing clinical presentation, treatments, and outcomes in liver transplant recipients with COVID-19. A systematic search was performed for articles published up to June 15, 2020, revealing 223 liver transplant recipients with COVID-19 in 15 studies. Patients most commonly presented with fever (66.7%), dyspnea (34.0%), and diarrhea (28.4%). Of these, 77.7% required hospitalization, 24% had mild disease, 40% had moderate disease, and 36% had severe disease. Immunosuppression was modified in 32.8% of recipients. The case fatality rate was 19.3%. Dyspnea on presentation, diabetes mellitus, and age 60 years or older were significantly associated with increased mortality (P ≤ .01) with a trend to higher mortality rate observed in those with hypertension and those receiving corticosteroids at the time of COVID-19 diagnosis. The median time from symptoms to death was 11.5 days (2-45 days). In conclusion, liver transplant recipients with severe acute respiratory syndrome coronavirus 2 are overrepresented with regard to severe disease and hospitalizations. Older liver transplant patients with diabetes mellitus or hypertension, who are on maintenance corticosteroids, with a diagnosis of COVID-19 and describing breathlessness should be aggressively monitored for signs of deterioration because of the risk for mortality.

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Hospitalization and mortality rates in liver transplants recipients with coronavirus disease 2019 (COVID-19) are disproportionately high when compared to nontransplant counterparts regardless of age, time after transplant, or country of residence.

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Older age and diabetes are significant risk factors for death among liver transplant recipients with COVID-19.

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Liver transplant recipients presenting with dyspnea in the context of confirmed COVID-19 are at an independently increased risk for mortality and should undergo intensive monitoring for signs of clinical deterioration.

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An immunosuppression regimen including corticosteroids at the time of COVID-19 infection and a history of hypertension demonstrate a trend to increased mortality in recipients of liver transplant with COVID-19.

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Further data are required before standardized recommendations regarding the utility of COVID-19–directed therapy or immune therapy modulation in the context of COVID-19 can be made.