Systematic review: pre- and post-operative prognostic value of cardiopulmonary exercise testing in liver transplant candidates

Home-based LIver FrailTy Intervention (LIFT) in Transplant Candidates: A Feasibility Study

BACKGROUND

Frailty is prevalent in end-stage liver disease and predicts higher waitlist and posttransplant mortality. Despite association of frailty with poor clinical outcomes, evidence-based interventions to reverse frailty remain scarce.

METHODS

In this pilot study, we tested the feasibility of a novel home-based frailty intervention using home exercise equipment, a smartphone application, and remote frailty assessments to create a dynamic and personalized exercise program for patients with cirrhosis evaluated for liver transplantation.

RESULTS

Fifty-four patients (mean 57.2 [±9.9] y, 59% men) enrolled in the study, with a mean Model for End-Stage Liver Disease-Na 16.9 (±5.8; 70% decompensated). The mean baseline Liver Frailty Index (LFI) was 3.59 (±0.60). The mean follow-up time was 259 (±190) d and the mean change in LFI at the end of the intervention was -0.11 (3.59 versus 3.48, P  = 0.05), representing a clinically meaningful improvement in frailty previously associated with increased survival. In comparison, the retrospective control group, which had similar demographics and clinical characteristics as the intervention group, did not show a significant change in LFI (3.97 versus 3.91, P  = 0.57). Fifty-six percent of patients were adherent (fully or partially) to recommended levels of exercise, and adherence rates declined from 1 to 3 mo after enrollment, underscoring the need to maintain patient engagement in exercise.

CONCLUSIONS

This study shows that a home-based frailty intervention is feasible. The intervention led to significant improvement in frailty, which was not seen in the retrospective control group. Future studies, including randomized controlled trials, are necessary to further assess the efficacy of the intervention and also determine its impact on downstream clinical outcomes.

Advanced Liver Fibrosis Impairs Cardiorespiratory Fitness in Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease

BACKGROUND

MASLD is a leading reason for liver transplant waitlisting. The relationship between cardiorespiratory fitness (CRF) and liver fibrosis in patients with MASLD remains unclear. This study aims to provide further evidence supporting the relationship between liver fibrosis and CRF.

METHODS

Participants with MASLD across various fibrosis stages, including those with cirrhosis awaiting liver transplantation from three U.S. transplant centers, underwent cardiopulmonary exercise testing (CPX). We compared participants based on fibrosis stage (F0-F1, F2-F3, and F4) and CPX parameters such as VO2peak, respiratory exchange ratio (RER), ventilatory efficiency (VE/VCO2), double product (DP) and chronotropic incompetence (CI). Multivariable models were then built to evaluate factors associated with these parameters.

RESULTS

Sixty-one participants underwent CPX testing across three centers. Participants with F4 had lower VO2peak (11.8 mL/kg/min) compared to F0-F1 (22.2 mL/kg/min) and F2-F3 (22.9 mL/kg/min), p < 0.001. Participants with F4 had higher RER (median 1.25) compared to F0-F1 (1.08) and F2-F3 (1.05), p = 0.001. Similarly, F4 participants exhibited higher VE/VCO2 (median 36.5) compared to F0-F1 (31) and F2-F3 (30), p < 0.001. Additionally, F4 participants had lower DP values (median 17,696) compared to F0-F1 (25,460) and F2-F3 (25,372), and higher prevalence of CI (90%) compared to F0-F1 (39%) and F2-F3 (25%), both p =  < 0.001. Multivariable modeling confirmed advanced fibrosis (F > 3) as an independent predictor of low CRF.

CONCLUSIONS

In MASLD patients, advanced liver fibrosis, particularly cirrhosis, is associated with reduced CRF and poorer hemodynamic performance during CPX. Prioritizing exercise training for those in earlier stages (F3) may prevent fitness decline, which could hinder physical training and liver transplantation candidacy.

A First Diastolic Function Evaluation in the Personalized Exercise Prescription Program for Solid Organs Transplanted Subjects: Is Atrial Strain Useful?

Background/Objectives: Solid organ transplant recipients (OTR) have been recently involved in exercise prescription programs in order to reduce the high prevalence of cardiovascular diseases. The normal systolic and diastolic cardiac function is fundamental to personalizing the prescription. Diastolic dysfunction can be associated to a higher risk of cardiovascular events and left atrial (LA) strain is an emerging parameter in the evaluation of diastolic compromising, especially in subjects with preserved ejection fraction. Left atrial (LA) strain has never been explored in this category. The study aimed to evaluate the contribution of the LA strain in the assessment of diastolic function of OTR and its potential contribution in the exercise program. Methods: 54 solid OTR (liver and kidney transplants) regularly trained for at least 12 months in a home-based, partially supervised model at moderate intensity estimated by cardiopulmonary exercise test, underwent a complete echocardiographic analysis. The measured variables included left ventricle systolic function (ejection fraction, EF), diastolic function (E/A and E/E'), LA indexed volumes, LA peak atrial longitudinal strain (PALS) and LA peak atrial contraction strain (PACS). The data were compared to those of 44 healthy subjects (HS). Results: The OTR showed an overweight condition (BMI: 25.79 ± 2.92 vs. 22.25 ± 2.95; p < 0.01). Both groups showed a preserved systolic function (EF: OTR 63.1 ± 3.5% vs. HS 66.9 ± 6.1; p < 0.001), while diastolic standard parameters were significantly different (E/A, 1.01 ± 0.4 vs. 1.96 ± 0.74; p < 0.001; E/E', 9.2 ± 2.7 vs. 6.9 ± 1.3; p < 0.001, in OTR and HS respectively) despite being normal. LA strain was significantly lower in OTR vs. HS (4C PALS, 33.7 ± 9.7 vs. 45.4 ± 14.19; p < 0.001; 4C PACS, 15.9 ± 6.7 vs. 11.6 ± 7.5; p = 0.006; 2C PALS, 35.3 ± 11.1 vs. 47.6 ± 14.9; p < 0.001; 2C PALS, 17.4 ± 4.9 vs. 13.2 ± 14.97; p = 0.001; in OTR and HS respectively). A specific correlation of two- and four-chamber PACs and PALs with BMI has been observed (R for 4C PALS -0.406 ** and 2C PALS -0.276 *). Conclusions: These findings suggest that the coexistence of increased bodyweight in asymptomatic OTR patients can exacerbate the impairment of LA strains. LA strain detection could be useful in the development of a personalized exercise program for OTRs, especially for asymptomatic subjects and those with elevated cardiovascular risk profile, to potentially manage the exercise program in the long term. Larger studies will confirm the role via an eventual structured clinical score index.

Cardiorespiratory Fitness From Cardiopulmonary Exercise Testing Is a Comprehensive Risk-stratifying Tool in Liver Transplant Candidates

Background

Cardiovascular disease and physical decline are prevalent and associated with morbidity/mortality in liver transplant (LT) patients. Cardiopulmonary exercise testing (CPX) provides comprehensive cardiopulmonary and exercise response assessments. We investigated cardiorespiratory fitness (CRF) and cardiac stress generated during CPX in LT candidates.

Methods

LT candidates at 2 centers underwent CPX. Standard-of-care cardiac stress testing (dobutamine stress echocardiography, DSE) results were recorded. Physical function was assessed with liver frailty index and 6-min walk test. CPX/DSE double products were calculated to quantify cardiac stress. To better study the association of CPX-derived metrics with physical function, the cohort was divided into 2 groups based on 6-min walk test median (372 m).

Results

Fifty-four participants (62 ± 8 y; 65% men, Model for End-Stage Liver Disease-Na 14 [10-18]) underwent CPX. Peak oxygen consumption was 14.1 mL/kg/min for an anerobic threshold of 10.2 mL/kg/min, with further CRF decline in the lower 6MWT cohort despite lack of liver frailty index-frailty in 90%. DSE was nondiagnostic in 18% versus 4% of CPX (P = 0.058). All CPX were negative for ischemia. A double product of ≥25 000 was observed in 32% of CPX and 11% of DSE (P = 0.020). Respiratory function testing was normal. No patient presented major cardiovascular events at 30 d post-LT.

Conclusions

CPX provided efficient and effective combined cardiopulmonary risk and frailty assessments of LT candidates in a 1-stop test. The CRF was found to be very low despite preserved physical function or lack of frailty.

Cardiovascular disease assessment and management in liver transplantation

The prevalence and mortality related to end-stage liver disease (ESLD) continue to rise globally. Liver transplant (LT) recipients continue to be older and have inherently more comorbidities. Among these, cardiac disease is one of the three main causes of morbidity and mortality after LT. Several reasons exist including the high prevalence of associated risk factors, which can also be attributed to the rise in the proportion of patients undergoing LT for metabolic dysfunction-associated steatohepatitis (MASH). Additionally, as people age, the prevalence of now treatable cardiac conditions, including coronary artery disease (CAD), cardiomyopathies, significant valvular heart disease, pulmonary hypertension, and arrhythmias rises, making the need to treat these conditions critical to optimize outcomes. There is an emerging body of literature regarding CAD screening in patients with ESLD, however, there is a paucity of strong evidence to support the guidance regarding the management of cardiac conditions in the pre-LT and perioperative settings. This has resulted in significant variations in assessment strategies and clinical management of cardiac disease in LT candidates between transplant centres, which impacts LT candidacy based on a transplant centre's risk tolerance and comfort level for caring for patients with concomitant cardiac disease. Performing a comprehensive assessment and understanding the potential approaches to the management of ESLD patients with cardiac conditions may increase the acceptance of patients, who appear too complex, but rather require extra evaluation and may be reasonable candidates for LT. The unique physiology of ESLD can profoundly influence preoperative assessment, perioperative management, and outcomes associated with underlying cardiac pathology, and requires a thoughtful multidisciplinary approach. The strategies proposed in this manuscript attempt to review the latest expert experience and opinions and provide guidance to practicing clinicians who assess and treat patients being considered for LT. These topics also highlight the gaps that exist in the comprehensive care of LT patients and the need for future investigations in this field.

Home-based EXercise and motivAtional programme before and after Liver Transplantation (EXALT): study protocol for phase II two-centre, randomised controlled trial

INTRODUCTION

Physical frailty is associated with increased mortality and poor quality of life (QoL) before and after liver transplantation (LT). Evidence is lacking on how to tailor exercise and behavioural techniques in this patient population.

METHODS AND ANALYSIS

Home-based EXercise and motivAtional programme before and after Liver Transplantation (EXALT) is a phase 2b, open-label, two-centre randomised controlled clinical trial designed to investigate whether a remotely monitored 'home-based exercise and theory-based motivation support programme (HBEP)' before and after LT improves QoL in LT recipients. Adult patients awaiting a primary LT will be assessed for eligibility at two LT centres (Birmingham, Royal Free London). Participants will be randomly assigned (1:1) to receive either an HBEP while on the LT waiting list through to 24 weeks after LT (Intervention) or a patient exercise advice leaflet (Control). Using a standard method of difference in means (two-sided significance level 0.05; power 0.90) and accounting for a 35% attrition/withdrawal rate, a minimum of 133 patients will be randomised to each treatment group. The primary outcome measure will be assessed using intention-to-treat analysis of the difference in the Physical Component Score of Short form-36 version 2.0 health-related QoL questionnaire between the groups at 24 weeks post-LT.

ETHICS AND DISSEMINATION

The protocol was approved by the South Central-Hampshire A National Research Ethics Committee. Recruitment into the EXALT trial started in May 2022 and is due to end in June 2024, with 217/266 patients randomised to date. The intervention follow-up is due to finish in May 2026. The findings of this trial will be disseminated through peer-reviewed publications, conferences and social media.

TRIAL REGISTRATION NUMBER

ISRCTN13476586.

Frailty in liver transplantation: Exploring prescribing exercise as medicine to improve patient outcomes

Liver transplantation (LT) represents a curative avenue for individuals with advanced chronic liver disease. Given the inherent illness severity of LT candidates, identifying patients at greater risk for adverse outcomes before and after transplantation is paramount. Approximately 50% of cirrhotic patients are frail and have considerable functional impairment. Various measures have been used to assess frailty, including performance-based tests and functional status evaluations. Frailty carries significant prognostic implications and predicts both mortality and pre- and post-LT complications. Contributing factors to frailty in this population include sarcopenia, malnutrition, inflammation, and psychosocial factors. Recognizing the prevalence of frailty among LT candidates, exercise interventions have been developed to improve physical frailty and offer potential to improve patient outcomes. While many interventions have demonstrated efficacy without notable adverse events, the absence of a universally accepted standard for exercise prescription underscores the variability in intervention elements and patient adherence. Given the safety profile of exercise interventions, there remains a critical need for standardized protocols and guidelines to optimize exercise regimens for LT candidates. This review delves into the landscape of frailty among LT candidates, elucidating its etiological underpinnings, impact on outcomes, utilization of exercise interventions, and the efficacy of exercise programs in reducing the burden frailty in those awaiting LT.

Ventilatory efficiency as a prognostic factor for postoperative complications in patients undergoing elective major surgery: a systematic review

BACKGROUND

Major surgery is associated with high complication rates. Several risk scores exist to assess individual patient risk before surgery but have limited precision. Novel prognostic factors can be included as additional building blocks in existing prediction models. A candidate prognostic factor, measured by cardiopulmonary exercise testing, is ventilatory efficiency (VE/VCO2). The aim of this systematic review was to summarise evidence regarding VE/VCO2 as a prognostic factor for postoperative complications in patients undergoing major surgery.

METHODS

A medical library specialist developed the search strategy. No database-provided limits, considering study types, languages, publication years, or any other formal criteria were applied to any of the sources. Two reviewers assessed eligibility of each record and rated risk of bias in included studies.

RESULTS

From 10,082 screened records, 65 studies were identified as eligible. We extracted adjusted associations from 32 studies and unadjusted from 33 studies. Risk of bias was a concern in the domains 'study confounding' and 'statistical analysis'. VE/VCO2 was reported as a prognostic factor for short-term complications after thoracic and abdominal surgery. VE/VCO2 was also reported as a prognostic factor for mid- to long-term mortality. Data-driven covariable selection was applied in 31 studies. Eighteen studies excluded VE/VCO2 from the final multivariable regression owing to data-driven model-building approaches.

CONCLUSIONS

This systematic review identifies VE/VCO2 as a predictor for short-term complications after thoracic and abdominal surgery. However, the available data do not allow conclusions about clinical decision-making. Future studies should select covariables for adjustment a priori based on external knowledge.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42022369944).

Enhancing ACLF prediction by integrating sarcopenia assessment and frailty in liver transplant candidates on the waiting list

Background & Aims

Malnutrition, sarcopenia, and frailty are prevalent in cirrhosis. We aimed to assess the correlation between assessment tools for malnutrition, sarcopenia, and frailty in patients on the liver transplant (LT) waiting list (WL), and to identify a predictive model for acute-on-chronic liver failure (ACLF) development.

Methods

This prospective single-center study enrolled consecutive patients with cirrhosis on the WL for LT (May 2019-November 2021). Assessments included subjective global assessment, CT body composition, skeletal muscle index (SMI), ultrasound thigh muscle thickness, sarcopenia HIBA score, liver frailty index (LFI), hand grip strength, and 6-minute walk test at enrollment. Correlations were analyzed using Pearson's correlation. Competing risk regression analysis was used to assess the predictive ability of the liver- and functional physiological reserve-related variables for ACLF.

Results

A total of 132 patients, predominantly with decompensated cirrhosis (87%), were included. Our study revealed a high prevalence of malnutrition (61%), sarcopenia (61%), visceral obesity (20%), sarcopenic visceral obesity (17%), and frailty (10%) among participants. Correlations between the assessment tools for sarcopenia and frailty were poor. Sarcopenia by SMI remained prevalent when frailty assessments were not usable. After a median follow-up of 10 months, 39% of the patients developed ACLF on WL, while 28% experienced dropouts without ACLF. Multivariate analysis identified MELD-Na, SMI, and LFI as independent predictors of ACLF on the WL. The predictive model MELD-Na-sarcopenia-LFI had a C-statistic of 0.85.

Conclusions

The poor correlation between sarcopenia assessment tools and frailty underscores the importance of a comprehensive evaluation. The SMI, LFI, and MELD-Na independently predicted ACLF development in WL. These findings enhance our understanding of the relationship between sarcopenia, frailty, and ACLF in patients awaiting LT, emphasizing the need for early detection and intervention to improve WL outcomes.

Impact and implications

The relationship between sarcopenia and frailty assessment tools, as well as their ability to predict acute-on-chronic liver failure (ACLF) in patients on the liver transplant (LT) waiting list (WL), remains poorly understood. Existing objective frailty screening tests have limitations when applied to critically ill patients. The correlation between sarcopenia and frailty assessment tools was weak, suggesting that they may capture different phenotypes. Sarcopenia assessed by skeletal muscle index, frailty evaluated using the liver frailty index, and the model for end-stage liver disease-Na score independently predicted the development of ACLF in patients on the WL. Our findings support the integration of liver frailty index and skeletal muscle index assessments at the time of inclusion on the WL for LT. This combined approach allows for the identification of a specific patient subgroup with an increased susceptibility to ACLF, underscoring the importance of early implementation of targeted treatment strategies to improve outcomes for patients awaiting LT.

Editorial: Enhancing frailty assessment in liver transplantation candidates-The role of the Duke Activity Status Index in predicting mortality and guiding prehabilitation

This article is linked to Williams et al papers. To view these articles, visit https://doi.org/10.1111/apt.17834 and https://doi.org/10.1111/apt.17874

Duke Activity Status Index and Liver Frailty Index predict mortality in ambulatory patients with advanced chronic liver disease: A prospective, observational study

BACKGROUND

There remains a lack of consensus on how to assess functional exercise capacity and physical frailty in patients with advanced chronic liver disease (CLD) being assessed for liver transplantation (LT). Aim To investigate prospectively the utility of the Duke Activity Status Index (DASI) and Liver Frailty Index (LFI) in ambulatory patients with CLD.

AIM

To investigate prospectively the utility of the Duke Activity Status Index (DASI) and Liver Frailty Index (LFI) in ambulatory patients with CLD.

METHODS

We recruited patients from outpatient clinics at University Hospitals Birmingham, UK (2018-2019). We prospectively collated the DASI and LFI to identify the prevalence of, respectively, functional capacity and physical frailty, and to evaluate their accuracy in predicting overall and pre-LT mortality.

RESULTS

We studied 307 patients (57% male; median age 54 years; UKELD 52). Median DASI score was 28.7 (IQR 16.2-50.2), mean LFI was 3.82 (SD = 0.72), and 81% were defined either 'pre-frail' or 'frail'. Female sex and hyponatraemia were significant independent predictors of both DASI and LFI. Age and encephalopathy were significant independent predictors of LFI, while BMI significantly predicted DASI. DASI and LFI were significantly related to overall (HR 0.97, p = 0.001 [DASI], HR 2.04, p = 0.001 [LFI]) and pre-LT mortality (HR 0.96, p = 0.02 [DASI], HR 1.94, p = 0.04 [LFI]).

CONCLUSIONS

Poor functional exercise capacity and physical frailty are highly prevalent among ambulatory patients with CLD who are being assessed for LT. The DASI and LFI are simple, low-cost tools that predict overall and pre-LT mortality. Implementation of both should be considered in all outpatients with CLD to highlight those who may benefit from targeted nutritional and exercise interventions.

Brief PROMIS Assessment Screens for Frailty and Predicts Hospitalizations in Liver Transplant Candidates

BACKGROUND

Frailty is prevalent in patients with end-stage liver disease and predicts waitlist mortality, posttransplant mortality, and frequency of hospitalizations. The Liver Frailty Index (LFI) is a validated measure of frailty in liver transplant (LT) candidates but requires an in-person assessment.

METHODS

We studied the association between patient-reported physical function and LFI in a single-center prospective study of adult patients with cirrhosis undergoing LT evaluation from October 2020 to December 2021. Frailty was assessed with the LFI and 4-m gait speed. Patient-reported physical function was evaluated using a brief Patient-Reported Outcomes Measurement Information System (PROMIS) survey.

RESULTS

Eighty-one LT candidates were enrolled, with a mean model of end-stage liver disease-sodium of 17.6 (±6.3). The mean LFI was 3.7 (±0.77; 15% frail and 59% prefrail) and the mean PROMIS Physical Function score was 45 (±8.6). PROMIS Physical Function correlated with LFI ( r  = -0.54, P  < 0.001) and 4-m gait speed ( r  = 0.48, P  < 0.001). The mean hospitalization rate was 1.1 d admitted per month. After adjusting for age, sex, and model of end-stage liver disease-sodium, patient-reported physical function-predicted hospitalization rate ( P  = 0.001).

CONCLUSIONS

This study suggests that a brief patient-reported outcome measure can be used to screen for frailty and predict hospitalizations in patients with cirrhosis.

Walking exercise through smartphone application plus branched-chain amino acid supplementation benefits skeletal muscle mass and strength in liver cirrhosis: A prospective control trial

INTRODUCTION AND OBJECTIVES

Whether a combination of exercise and branched-chain amino acid (BCAA) supplementation was more beneficial than those given alone in sarcopenia related to liver cirrhosis (LC) is unknown. Widely used smartphone applications provide continuous and easily expandable management of chronic liver disease (CLD). This study is to investigate the effects of unsupervised walking exercise using WeChat combined with BCAA supplementation on skeletal muscle mass and strength in LC.

MATERIALS AND METHODS

The 127 LC patients of Child-Pugh A/B were assigned to group A (BCAA supplements, n=42), group B (walking exercise, n=43) and group C (walking exercise plus BCAA supplements, n=42). Laboratory data, average daily steps, serum BCAA, skeletal muscle mass index (SMI) and grip strength were analyzed pre- and 3 months after interventions.

RESULTS

Of the 124 patients who completed interventions, albumin and daily steps were significantly increased in all groups (p=0.0001). Post-intervention BCAA were significantly elevated in group A (A vs B, p=0.001) and C (C vs B, p=0.012;). While post-intervention daily steps in group B (B vs A, p=0.0001) and C (C vs A, p=0.0001) were higher. Grip strength (C vs A, p=0.020; C vs B, p=0.036) and SMI (C vs A, p=0.035; C vs B, p=0.012) were increased in group C. Prevalence of sarcopenia was significantly decreased in group C (p=0.015).

CONCLUSIONS

A combination of unsupervised walking exercise using smartphone applications and BCAA supplementation might be an effective and safe treatment for cirrhosis patients with Child-Pugh A/B to improve skeletal muscle mass and strength or to prevent progress of sarcopenia.

Estimated standard values of aerobic capacity according to sex and age in a Japanese population: A scoping review

Aerobic capacity is a fitness measure reflecting the ability to sustain whole-body physical activity as fast and long as possible. Identifying the distribution of aerobic capacity in a population may help estimate their health status. This study aimed to estimate standard values of aerobic capacity (peak oxygen uptake [Formula: see text] and anaerobic threshold [AT]/kg) for the Japanese population stratified by sex and age using a meta-analysis. Moreover, the comparison of the estimated standard values of the Japanese with those of other populations was performed as a supplementary analysis. We systematically searched original articles on aerobic capacity in the Japanese population using PubMed, Ichushi-Web, and Google Scholar. We meta-analysed [Formula: see text] (total: 78,714, men: 54,614, women: 24,100) and AT (total: 4,042, men: 1,961, women: 2,081) data of healthy Japanese from 21 articles by sex and age. We also searched, collected and meta-analysed data from other populations. Means and 95% confidence intervals were calculated. The estimated standard values of [Formula: see text] (mL/kg/min) for Japanese men and women aged 4-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 47.6, 51.2, 43.2, 37.2, 34.5, 31.7, 28.6, and 26.3, and 42.0, 43.2, 33.6, 30.6, 27.4, 25.6, 23.4, and 23.1, respectively. The AT/kg (mL/kg/min) for Japanese men and women aged 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 21.1, 18.3, 16.8, 15.9, 15.8, and 15.2, and 17.4, 17.0, 15.7, 15.0, 14.5, and 14.2, respectively. Herein, we presented the estimated standard values of aerobic capacity according to sex and age in a Japanese population. In conclusion, aerobic capacity declines with ageing after 20-29 years of age. Additionally, aerobic capacity is lower in the Japanese population than in other populations across a wide range of age groups. Standard value estimation by meta-analysis can be conducted in any country or region and for public health purposes.

Liver transplantation in the patient with physical frailty

Frailty is a decline in functional reserve across multiple physiological systems. A key component of frailty is sarcopenia, which denotes a loss of skeletal muscle mass and impaired contractile function that ultimately result in physical frailty. Physical frailty/sarcopenia are frequent and contribute to adverse clinical outcomes before and after liver transplantation. Frailty indices, including the liver frailty index, focus on contractile dysfunction (physical frailty), while cross-sectional image analysis of muscle area is the most accepted and reproducible measure to define sarcopenia. Thus, physical frailty and sarcopenia are interrelated. The prevalence of physical frailty/sarcopenia is high in liver transplant candidates and these conditions have been shown to adversely impact clinical outcomes including mortality, hospitalisations, infections, and cost of care both before and after transplantation. Data on the prevalence of frailty/sarcopenia and their sex- and age-dependent impact on outcomes are not consistent in patients on the liver transplant waitlist. Physical frailty and sarcopenic obesity are frequent in the obese patient with cirrhosis, and adversely affect outcomes after liver transplantation. Nutritional interventions and physical activity remain the mainstay of management before and after transplantation, despite limited data from large scale trials. In addition to physical frailty, there is recognition that a global evaluation including a multidisciplinary approach to other components of frailty (e.g., cognition, emotional, psychosocial) also need to be addressed in patients on the transplant waitlist. Recent advances in our understanding of the underlying mechanisms of sarcopenia and contractile dysfunction have helped identify novel therapeutic targets.

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.

Six-Minute walk distance predicts outcomes in liver transplant candidates

A 6-minute walk test is a simple tool for assessing submaximal exercise capacity. We sought to determine whether a 6-minute walk distance (6MWD) predicts outcomes in patients with cirrhosis. The Pulmonary Vascular Complications of Liver Disease 2 study is a multicenter, prospective cohort study that enrolled adults with portal hypertension during liver transplantation evaluation. We excluded subjects with an incident or prevalent portopulmonary hypertension. The 6-minute walk test was performed using standardized methods. Cox proportional hazards modeling and multivariable linear regression analysis were performed to determine the relationship between baseline 6MWD and outcomes. The study sample included 352 subjects. The mean 6MWD was 391±101 m. For each 50-meter decrease in 6MWD, there was a 25% increase in the risk of death (HR 1.25, 95% CI [1.11, 1.41], p < 0.001) after adjustment for age, gender, body mass index, MELD-Na, and liver transplant as a time-varying covariate. In a multistate model, each 50-meter decrease in 6MWD was associated with an increased risk of death before the liver transplant ( p < 0.001) but not after the transplant. 6MWD was similar to MELD-Na in discriminating mortality. Each 50-meter decrease in 6MWD was associated with an increase in all-cause ( p < 0.001) and transplant-free hospitalizations ( p < 0.001) in multivariable models for time-to-recurrent events. Shorter 6MWD was associated with worse Short Form-36 physical ( p < 0.001) and mental component scores ( p = 0.05). In conclusion, shorter 6MWD is associated with an increased risk of death, hospitalizations, and worse quality of life in patients evaluated for liver transplantation. The 6-minute walk distance may be a useful adjunct for risk assessment in patients undergoing liver transplant evaluation.

Personality Traits in Patients With Cirrhosis Are Different From Those of the General Population and Impact Likelihood of Liver Transplantation

BACKGROUND

Personality traits influence clinical outcomes in chronic diseases, but their impact in cirrhosis is unknown. We studied the personality of patients with cirrhosis undergoing liver transplant (LT) evaluation and determined their correlation to clinical outcomes.

METHODS

A multicenter' prospective study of adult patients undergoing LT evaluation was performed from January 2018 to October 2019. The "Big Five" personality traits of conscientiousness, extraversion, openness, neuroticism, and agreeableness plus agency were assessed with the Midlife Development Inventory Personality Scale and compared with the general population. Frailty was assessed with the Liver Frailty Index.

RESULTS

Two hundred sixty-three LT candidates were enrolled. Twenty-four percent had hepatitis C virus, 25% nonalcoholic steatohepatitis, and 25% ethyl alcohol (mean model for end-stage liver disease = 15.7). Compared with the general population, LT candidates had higher openness (3.1 versus 2.9; P < 0.001), extraversion (3.2 versus 3.1; P < 0.001), agreeableness (3.5 versus 3.4; P = 0.04), agency (2.9 versus 2.6; P < 0.001), neuroticism (2.2 versus 2.1; P = 0.001), and lower conscientiousness (3.3 versus 3.4; P = 0.007). Patients with higher conscientiousness were more likely to receive an LT (HR = 2.76; P = 0.003).

CONCLUSIONS

Personality traits in LT candidates differ significantly from the general population, with higher conscientiousness associated with a higher likelihood of receiving a transplant.

Does Exercise Training Improve Physical Fitness and Health in Adult Liver Transplant Recipients? A Systematic Review and Meta-analysis

BACKGROUND

The impaired physical fitness of end-stage liver disease patients often persists after liver transplantation (LT) and compromises posttransplant recovery. This systematic review and meta-analysis evaluated evidence supporting the potential of exercise training to improve physical fitness and health-related quality of life (HRQOL) after LT.

METHODS

Bibliographic searches identified all randomized controlled trials (RCTs) comparing aerobic and strength training versus usual care after LT. Risk of bias was assessed, and study outcomes measuring physical fitness and HRQOL were extracted. Meta-analysis was performed if at least 3 studies reported on an outcome.

RESULTS

Eight RCTs (n = 334) were identified. Methodological study quality varied and was poorly reported. Meta-analyses showed a trend for favorable effects of exercise on cardiorespiratory fitness (peak oxygen uptake or 6-min walking distance; 6 studies, n = 275; standardized mean difference: 0.23, 95% confidence interval [CI], -0.01 to 0.48) and of strength training either or not combined with aerobic training on muscular fitness (dynamometry-assessed muscle strength or 30-s sit-to-stand test; 3 studies, n = 114; standardized mean difference: 0.34, 95% CI, -0.03 to 0.72). A favorable effect was found for exercise on the Short-Form Health Survey-36 HRQOL physical function subcomponent (3 studies, n = 194; mean difference: 9.1, 95% CI, 0.3-17.8). No exercise-related adverse events were observed.

CONCLUSIONS

RCTs indicate that exercise training in LT recipients is safe, improves physical function aspects of HRQOL, and may benefit cardiorespiratory and muscular fitness. The strength of evidence is, however, limited by the low number of patients and study quality. More adequately powered, high-quality RCTs are warranted.

Identifying the limitations of cardiopulmonary exercise testing prior to esophagectomy using a pooled analysis of patient-level data

Preoperative cardiopulmonary exercise testing (CPET) provides an objective assessment of aerobic fitness in patients undergoing surgery. While peak oxygen uptake during exercise (VO2peak) and anaerobic threshold have demonstrated a moderate correlation with the development of complications following esophagectomy, no clinically useful threshold values have been defined. By pooling patient level data from existing studies, we aimed to define optimal thresholds for preoperative CPET parameters to predict patients at high risk of postoperative complications. Studies reporting on the relationship between preoperative CPET variables and post-esophagectomy complications were determined from a comprehensive literature search. Patient-level data were obtained from six contributing centers for pooled-analyses. Outcomes of interest included cardiopulmonary and non-cardiopulmonary complications, unplanned intensive care unit readmission, and 90-day and 12-month all-cause mortality. Receiver operating characteristic curves and logistic regression models estimated the predictive value of CPET parameters for each individual outcome of interest. This analysis comprised of 621 patients who underwent CPET prior to esophagectomy during the period from January 2004 to March 2017. For both anaerobic threshold and VO2peak, none of the receiver operating characteristic curves achieved an area under the curve value > 0.66 for the outcomes of interest. The discriminatory ability of CPET for determining high-risk patients was found to be poor in patients undergoing an esophagectomy. CPET may only carry an adjunct role to clinical decision-making.

The role of acute in-patient rehabilitation on short-term outcomes after liver transplantation: A systematic review of the literature and expert panel recommendations

BACKGROUND

The indication and surgical complexity of orthotopic liver transplantation underscore the need for strategies to optimize the recovery for transplant recipients. We conducted a systematic review aimed at identifying, evaluating, and synthesizing the evidence examining the effect of in-patient rehabilitation for liver transplant recipients and provide related practice recommendations.

METHODS

Health research databases were systematically reviewed for studies that included adults who received liver transplantation and participated in acute, post-transplant rehabilitation. Postoperative morbidity, mortality, length of hospital stay, length of intensive care unit stay, and other markers of surgical recovery were extracted. Practice recommendations are provided by an international panel using GRADE.

RESULTS

Twelve studies were included in the review (including 3901 participants). Rehabilitation interventions varied widely in design and composition; however, details regarding intervention delivery were poorly described in general. The quality of evidence was rated as very low largely owing to "very serious" imprecision, poor reporting, and limited data from comparative studies. Overall, the studies suggest that in-patient rehabilitation for recipients of liver transplantation is safe, tolerable, and feasible, and may benefit functional outcomes.

CONCLUSION

Two practice recommendations related to in-patient rehabilitation following LT were yielded from this review: (1) it is safe, tolerable, and feasible; and (2) it improves postoperative functional outcomes. Each of the recommendations are weak and supported by low quality of evidence. No recommendation could be made related to benefits or harms for clinical, physiological, and other outcomes. Adequately powered and high quality randomized controlled trials are urgently needed in this area.

Association of physiological reserve measures with adverse outcomes following liver transplantation

Background and Aim

The comparative utility of physiological reserve measures in predicting important clinical outcomes following liver transplantation (LT) requires further study. The aim of this work was therefore to compare the utility of physiological reserve measures in predicting early adverse clinical outcomes post‐LT.

Methods

A single‐center, retrospective cohort study of LT patients consecutively recruited between 1 January 2015, and 31 August 2020. Outcomes measured were sepsis and death within 12 months of LT, hospital length of stay (LOS), and intensive care LOS. Physiological reserve measures were handgrip strength, mid‐arm muscle circumference, and cardiopulmonary exercise testing (CPET) measures. Analysis was performed using univariate and multivariate logistic regression for sepsis and death, and univariate and multivariate Cox regression for hospital and intensive care LOS.

Results

Data were obtained for 109 subjects. Patients were predominantly (64%) male with a median (interquartile range [IQR]) age of 57 (49–63) and median (IQR) Model for End‐Stage Liver Disease score of 16 (11–21). In multivariate analysis, the odds of sepsis were lower in patients in the highest versus lowest tertile (odds ratio = 0.004; 95% confidence interval [CI] 0.00–0.13; P = 0.002). Hospital LOS was linearly associated with handgrip strength (hazard ratio [HR] = 1.03; 95% CI 1.00–1.06; P = 0.03) in multivariate analysis. Intensive care LOS was associated with peak VO₂ (HR 1.83; 95% CI 1.06–3.16; P = 0.03) and V_E/VCO₂ slope (HR 0.71; 95% CI 0.58–0.88; P = 0.002) in multivariate analysis.

Conclusion

Handgrip strength and CPET both identify candidates at high risk of adverse outcomes after LT.

Frailty and reduced gait speed are independently related to mortality of cirrhotic patients in long-term follow-up

INTRODUCTION AND OBJECTIVES

Frailty is characterized by a poor restoration of homeostasis after a stressor event. Although it is not usually diagnosed, it has been associated with decreased survival in cirrhotic patients. We aimed to evaluate the impact of frailty and decreased gait speed over survival in cirrhotic patients at long-term follow-up.

MATERIALS AND METHODS

We included stable cirrhotic patients Child-Pugh B-C or MELD ≥12, ≥50 years old. We performed a clinical evaluation, anthropometry, and laboratory tests. Frailty was diagnosed using Fried Frailty Index. We evaluated survival at a 4-year follow-up.

RESULTS

We included 126 patients; mean age 64±8.3 years, median MELD-Na 15[12-17], median follow-up was 881 [349-1277] days. The main etiology was MAFLD (31.4%). Frailty was diagnosed in 65.1% of patients. There were no significant differences in baseline characteristics per frailty condition. Mortality was higher in frail patients than non-frail patients (68.2% versus 20.6% at 48 months, respectively; p-value <0.001). The mean gait speed in frail and non-frail patients was 0.86±0.3m/s and 1.16±0.2m/s, respectively (p-value <0.001). Interestingly, 26.9% of patients presented a reduced gait speed (≤0.8m/s). Patients with decreased gait speed also had higher mortality than patients with normal gait speed (79.9% versus 40.8%, respectively; p-value <0.001). A multivariate-adjusted model showed that decreased gait speed (HR=3.27, 95%CI:1.74-6.14; p<0.001) and frailty (HR=4.24, 95%CI:1.89-9.51; p<0.001) were associated with mortality.

CONCLUSIONS

Frailty is independently associated with decreased survival at long-term follow-up. Reduced gait speed is strongly associated with mortality and could be a surrogate marker of frailty in clinical practice.

Exercise physiology in cirrhosis and the potential benefits of exercise interventions: A review

Reduction in muscle mass is a highly prevalent phenomenon in cirrhosis and is now well-documented to be associated with significant morbidity and mortality. Research into muscle loss in cirrhosis remains limited by an ongoing poor understanding of its relationship with muscle function, physical activity, and aerobic capacity. Alterations in exercise physiology have been documented in studies of individuals with cirrhosis that provide important information on physical function that is not captured by simple quantification of muscle mass. Despite expert consensus recommending regular exercise in end-stage liver disease to maintain muscle mass and function, there is little evidence guiding clinicians as to which form of exercise or delivery mechanism is most effective. It also remains unproven whether any specific intervention can alter clinically relevant outcomes. This review article summarizes the available literature regarding the changes in exercise physiology observed in cirrhosis, the associated impact on physical capacity, and the results of existing trials that examine the potential benefits of exercise delivery in patients with cirrhosis, particularly pertaining to their impact on exercise physiology.

Physical frailty in liver transplantation

In patients with cirrhosis, frailty represents a status of global physical dysfunction associated with a multiplicity of factors, including muscle wasting, undernutrition and malnutrition, and functional impairment. This condition is particularly prevalent among those with advanced cirrhosis, such as liver transplant (LT) candidates. Studies in this vulnerable population have demonstrated that its presence is independently predictive of adverse outcomes both pre- and post-transplantation, and thus that its incorporation into clinical practice could result in improved clinical decision-making, particularly regarding the identification of candidates for physical and nutritional interventions. There are, however, some limitations to its immediate incorporation into organ allocation prioritization models, including the wide heterogeneity of instruments used for measuring frailty, and particularly the lack of a single one suitable in all LT clinical scenarios (inpatient vs outpatient; pre- vs post-transplant). Finally, the data on the potential effects of frailty improvement on the diverse range of outcome measures are still preliminary.

Assessment of the Frail Patient With End-Stage Liver Disease: A Practical Overview of Sarcopenia, Physical Function, and Disability

Frailty has emerged as a powerful predictor of clinical outcomes (e.g., decompensation, hospitalization, mortality) in patients with end-stage liver disease (ESLD). It is therefore of paramount importance that all patients with ESLD undergo an assessment of frailty, to support life and death decision making (i.e., candidacy for critical care, transplantation) and aid with prioritization of evolving prehabilitation services (i.e., nutrition, physiotherapy, psychotherapy). This article aims to provide a practical overview of the recent advances in the clinical, radiological, and remote assessment tools of the frail patient with ESLD. Historically, clinicians have incorporated an assessment of frailty using the "end-of-the-bed test" or "eyeball test" into their clinical decision making. However, over the last decade, numerous nonspecific and specific tools have emerged. The current evidence supports the use of a combination of simple, user-friendly, objective measures to first identify frailty in ESLD (notably Clinical Frailty Scale, Liver Frailty Index), followed by a combination of serial tools to assess specifically sarcopenia (i.e., muscle ultrasound), physical function (i.e., chair stands, hand grip strength), functional capacity (i.e., 6-minute walk test), and physical disability (i.e., activities of daily living).

Wearables, Physical Activity, and Exercise Testing in Liver Disease

Physical inactivity is a major cause of deterioration in all forms of advanced liver disease. It is especially important as a driver of the components of the metabolic syndrome, with nonalcoholic fatty liver disease rapidly becoming the dominant cause of liver-related death worldwide. Growing realization of the health benefits of moderate-to-vigorous physical activity has captured the interest of persons who desire to improve their health, including those at risk for chronic liver injury. They are increasingly adopting wearable activity trackers to measure the activity that they seek to improve. Improved physical activity is the key lifestyle behavior that can improve cardiorespiratory fitness, which is most accurately measured with cardiopulmonary exercise testing (CPET). CPET is showing promise to identify risk and predict outcomes in transplant hepatology. Team effort among engaged patients, social support networks, and clinicians supported by web-based connectivity is needed to fully exploit the benefits of physical activity tracking.

Nutrition in Chronic Liver Disease: Consensus Statement of the Indian National Association for Study of the Liver

Malnutrition and sarcopenia are common in patients with chronic liver disease and are associated with increased risk of decompensation, infections, wait-list mortality and poorer outcomes after liver transplantation. Assessment of nutritional status and management of malnutrition are therefore essential to improve outcomes in patients with chronic liver disease. This consensus statement of the Indian National Association for Study of the Liver provides a comprehensive review of nutrition in chronic liver disease and gives recommendations for nutritional screening and treatment in specific clinical scenarios of malnutrition in cirrhosis in adults as well as children with chronic liver disease and metabolic disorders.

Normative Cardiopulmonary Exercise Test Responses at the Ventilatory Threshold in Canadian Adults 40 to 80 Years of Age

BACKGROUND

Physiologic and symptom responses at the ventilatory threshold (Tvent) during incremental cardiopulmonary exercise testing (CPET) can provide important prognostic information.

RESEARCH QUESTION

This study aimed to develop an updated normative reference set for physiologic and symptom responses at Tvent during cycle CPET (primary aim) and to evaluate previously recommended reference equations from a 1985 study for predicting Tvent responses (secondary aim).

STUDY DESIGN AND METHODS

Participants were adults 40 to 80 years of age who were free of clinically relevant disease from the Canadian Cohort Obstructive Lung Disease. Rate of oxygen consumption (V˙O₂) at Tvent was identified by two independent raters; physiologic and symptom responses corresponding to V˙O₂ at Tvent were identified by linear interpolation. Reference ranges (5th-95th percentiles) for responses at Tvent were calculated according to participant sex and age for 29 and eight variables, respectively. Prediction models were developed for nine variables (oxygen pulse, V˙O₂, rate of CO₂ production, minute ventilation, tidal volume, inspiratory capacity, end-inspiratory lung volume [in liters and as percentage of total lung capacity], and end-expiratory lung volume) using quantile regression, estimating the 5th (lower limit of normal), 50th (normal), and 95th (upper limit of normal) percentiles based on readily available participant characteristics. The two one-sided test of equivalence for paired samples evaluated the measured and 1985-predicted V˙O₂ at Tvent for equivalence.

RESULTS

Reference ranges and equations were developed based on 96 participants (49% men) with a mean ± SD age of 63 ± 9 years. Mean V˙O₂ at Tvent was 50% of measured V˙O₂ peak; the normal range was 33% to 66%. The 1985 reference equations overpredicted V˙O₂ at Tvent: mean difference in men, -0.17 L/min (95% CI, -0.25 to -0.09 L/min); mean difference in women, -0.19 L/min (95% CI, -0.27 to -0.12 L/min).

INTERPRETATION

A contemporary reference set of CPET responses at Tvent from Canadian adults 40 to 80 years of age is presented that differs from the previously recommended and often used reference set from 1985.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00920348; URL: www.clinicaltrials.gov.

Exercise and physical activity in cirrhosis: opportunities or perils

Reduced exercise capacity and impaired physical performance are observed in nearly all patients with liver cirrhosis. Physical activity and exercise are physiological anabolic stimuli that can reverse dysregulated protein homeostasis or proteostasis and potentially increase muscle mass and contractile function in healthy subjects. Cirrhosis is a state of anabolic resistance, and unlike the beneficial responses to exercise reported in physiological states, there are few systematic studies evaluating the response to exercise in cirrhosis. Hyperammonemia is a mediator of the liver-muscle axis with net skeletal muscle ammonia uptake in cirrhosis causing signaling perturbations, mitochondrial dysfunction with decreased ATP content, modifications of contractile proteins, and impaired ribosomal function, all of which contribute to anabolic resistance in cirrhosis and have the potential to impair the beneficial responses to exercise. English language-publications in peer-reviewed journals that specifically evaluated the impact of exercise in cirrhosis were reviewed. Most studies evaluated responses to endurance exercise, and readouts included peak or maximum oxygen utilization, grip strength, and functional capacity. Endurance exercise for up to 12 wk is clinically tolerated in well-compensated cirrhosis. Data on the safety of resistance exercise are conflicting. Nutritional supplements enhance the benefits of exercise in healthy subjects but have not been evaluated in cirrhosis. Whether the beneficial physiological responses with endurance exercise and increase in muscle mass with resistance exercise that occur in healthy subjects also occur in cirrhotics is not known. Specific organ-system responses, changes in body composition, or improved long-term clinical outcomes with exercise in cirrhosis need evaluation.

Preoperative cardiac assessment in liver transplant candidates

New and extended indications, older age, higher cardiovascular risk, and the long-standing cirrhosis-associated complications mandate specific skills for an appropriate preoperative assessment of the liver transplant (LT) candidate. The incidence of cardiac diseases (dysrhythmias, cardiomyopathies, coronary artery disease, valvular heart disease) are increasing among LT recipients: however, no consensus exists among clinical practice guidelines for cardiovascular screening and risk stratification. In spite of different "transplant center-centered protocols", basic "pillars" are common (electrocardiography, baseline echocardiography, functional assessment). Owing to intrinsic limitations, yields and relevance of noninvasive stress tests, under constant scrutiny even if used, are discussed, focusing the definition of the "high risk" candidate and exploring noninvasive imaging and new forms of stress imaging. The aim is to find an appropriate and rational stepwise algorithm. The final commitment is to select the right candidate for a finite resource, the graft, able to save (and change) lives.

Performance of cardiopulmonary exercise testing for the prediction of post-operative complications in non cardiopulmonary surgery: A systematic review

INTRODUCTION

Cardiopulmonary exercise testing (CPET) is widely used within the United Kingdom for preoperative risk stratification. Despite this, CPET's performance in predicting adverse events has not been systematically evaluated within the framework of classifier performance.

METHODS

After prospective registration on PROSPERO (CRD42018095508) we systematically identified studies where CPET was used to aid in the prognostication of mortality, cardiorespiratory complications, and unplanned intensive care unit (ICU) admission in individuals undergoing non-cardiopulmonary surgery. For all included studies we extracted or calculated measures of predictive performance whilst identifying and critiquing predictive models encompassing CPET derived variables.

RESULTS

We identified 36 studies for qualitative review, from 27 of which measures of classifier performance could be calculated. We found studies to be highly heterogeneous in methodology and quality with high potential for bias and confounding. We found seven studies that presented risk prediction models for outcomes of interest. Of these, only four studies outlined a clear process of model development; assessment of discrimination and calibration were performed in only two and only one study undertook internal validation. No scores were externally validated. Systematically identified and calculated measures of test performance for CPET demonstrated mixed performance. Data was most complete for anaerobic threshold (AT) based predictions: calculated sensitivities ranged from 20-100% when used for predicting risk of mortality with high negative predictive values (96-100%). In contrast, positive predictive value (PPV) was poor (2.9-42.1%). PPV appeared to be generally higher for cardiorespiratory complications, with similar sensitivities. Similar patterns were seen for the association of Peak VO2 (sensitivity 85.7-100%, PPV 2.7-5.9%) and VE/VCO2 (Sensitivity 27.8%-100%, PPV 3.4-7.1%) with mortality.

CONCLUSIONS

In general CPET's 'rule-out' capability appears better than its ability to 'rule-in' complications. Poor PPV may reflect the frequency of complications in studied populations. Our calculated estimates of classifier performance suggest the need for a balanced interpretation of the pros and cons of CPET guided pre-operative risk stratification.

Cardiac Imaging in Liver Transplantation Candidates: Current Knowledge and Future Perspectives

Cardiovascular dysfunction in cirrhotic patients is a recognized clinical entity commonly referred to as cirrhotic cardiomyopathy. Systematic inflammation, autonomic dysfunction, and activation of vasodilatory factors lead to hyperdynamic circulation with high cardiac output and low peripheral vascular resistance. Counter acting mechanisms as well as direct effects on cardiac cells led to systolic or diastolic dysfunction and electromechanical abnormalities, which are usually masked at rest but exposed at stress situations. While cardiovascular complications and mortality are common in patients undergoing liver transplantation, they cannot be adequately predicted by conventional cardiac examination including transthoracic echocardiography. Newer echocardiography indices and other imaging modalities such as cardiac magnetic resonance have shown increased diagnostic accuracy with predictive implications in cardiovascular diseases. The scope of this review was to describe the role of cardiac imaging in the preoperative assessment of liver transplantation candidates with comprehensive analysis of the future perspectives anticipated by the use of newer echocardiography indices and cardiac magnetic resonance applications.

Review article: impact of exercise on physical frailty in patients with chronic liver disease

BACKGROUND

Physical frailty is common in chronic liver disease and the setting of liver transplantation. It is associated with poor quality of life, increased hospitalisation and mortality. Despite this, the impact of exercise in these patients remains poorly understood.

AIM

To summarise the impact of physical exercise on physical frailty in patients with chronic liver disease until after liver transplantation.

METHODS

A MEDLINE and PubMed search was undertaken using the terms; "physical activity", "functional capacity", "exercise", "prehabilitation", "frailty", "liver cirrhosis", "liver failure", "liver transplantation" "chronic liver disease" and "end-stage liver disease" from January 1990 to June 2019.

RESULTS

Eleven studies (five randomised controlled, five observational, one case study) demonstrated that exercise improves VO₂ peak, anaerobic threshold, 6-minute walk distance, muscle mass/function and quality of life in patients with compensated and decompensated cirrhosis. Improvements were most significant with a combination of aerobic and resistance exercises at moderate-high intensity. The studies were small (n = 1-50) and mainly focused on supervised, hospital-based exercises, excluding patients with significant liver failure (MELD > 12). Seven studies (four randomised controlled and three observational) demonstrated that predominantly supervised (only one home-based) aerobic exercise after liver transplantation improves aerobic capacity, muscle mass/strength and quality of life. There was marked heterogeneity in timing, intensity and type of exercises.

CONCLUSION

Exercise improves key components of physical frailty (functional/aerobic capacity, sarcopenia) and quality of life in chronic liver disease and after liver transplantation. Understanding the type, compliance, intensity and duration of exercise and its impact on hard clinical outcomes should be the focus of future large controlled clinical trials.

Frailty in liver transplantation: An expert opinion statement from the American Society of Transplantation Liver and Intestinal Community of Practice

Frailty has emerged as a powerful predictor of outcomes in patients with cirrhosis and has inevitably made its way into decision making within liver transplantation. In an effort to harmonize integration of the concept of frailty among transplant centers, the AST and ASTS supported the efforts of our working group to develop this statement from experts in the field. Frailty is a multidimensional construct that represents the end-manifestation of derangements of multiple physiologic systems leading to decreased physiologic reserve and increased vulnerability to health stressors. In hepatology/liver transplantation, investigation of frailty has largely focused on physical frailty, which subsumes the concepts of functional performance, functional capacity, and disability. There was consensus that every liver transplant candidate should be assessed at baseline and longitudinally using a standardized frailty tool, which should guide the intensity and type of nutritional and physical therapy in individual liver transplant candidates. The working group agreed that frailty should not be used as the sole criterion for delisting a patient for liver transplantation, but rather should be considered one of many criteria when evaluating transplant candidacy and suitability. A road map to advance frailty in the clinical and research settings of liver transplantation is presented here.

Report from the American Society of Transplantation on frailty in solid organ transplantation

A consensus conference on frailty in kidney, liver, heart, and lung transplantation sponsored by the American Society of Transplantation (AST) and endorsed by the American Society of Nephrology (ASN), the American Society of Transplant Surgeons (ASTS), and the Canadian Society of Transplantation (CST) took place on February 11, 2018 in Phoenix, Arizona. Input from the transplant community through scheduled conference calls enabled wide discussion of current concepts in frailty, exploration of best practices for frailty risk assessment of transplant candidates and for management after transplant, and development of ideas for future research. A current understanding of frailty was compiled by each of the solid organ groups and is presented in this paper. Frailty is a common entity in patients with end-stage organ disease who are awaiting organ transplantation, and affects mortality on the waitlist and in the posttransplant period. The optimal methods by which frailty should be measured in each organ group are yet to be determined, but studies are underway. Interventions to reverse frailty vary among organ groups and appear promising. This conference achieved its intent to highlight the importance of frailty in organ transplantation and to plant the seeds for further discussion and research in this field.

Interventions to improve sarcopenia in cirrhosis: A systematic review

BACKGROUND

Sarcopenia, i.e., muscle loss is now a well-recognized complication of cirrhosis and in cases of non-alcoholic fatty liver disease can contribute to accelerate liver fibrosis leading to cirrhosis. Hence, it is imperative to study interventions which targets to improve sarcopenia in cirrhosis.

AIM

To examine the relationship between interventions such nutritional supplementation, exercise, combined life style intervention, testosterone replacement and trans jugular intrahepatic portosystemic shunt (TIPS) to improve muscle mass in cirrhosis.

METHODS

We search PubMed, EMBASE and Cochrane between June-August 2018, without a limiting period and the types of articles (RCTs, clinical trial, comparative study) in adult patients with sarcopenia and cirrhosis. The primary outcome of interest was improvement in muscle mass, strength and physical function interventions mentioned above. In the screening process, 154 full text articles were included in the review and 129 studies were excluded.

RESULTS

We identified 24 studies that met review inclusion criteria. The studies were diverse in terms of the design, setting, interventions, and outcome measurements. We performed only qualitative synthesis of evidence due to heterogeneity amongst studies. Risk of bias was medium in most of the included studies and low quality of evidence showed improvement in the muscle mass, strength and physical function following aerobic exercise. 60% of the included studies on the nutritional intervention, 100% of the studies on testosterone replacement in hypogonadal men and trans-jugular portosystemic shunt were proved to be effective in improving sarcopenia in cirrhosis.

CONCLUSION

Although the quality of evidence is low, the findings of our systematic review suggest improvement in the sarcopenia in cirrhosis with exercise, nutritional interventions, hormonal and TIPS interventions. High quality randomized controlled trials needed to further strengthen these findings.

Frailty and Outcomes After Liver Transplantation

Purpose of review

Frailty is an emerging concept in liver transplantation. We reviewed the literature for the tests of frailty which have been validated to predict outcomes in patients with cirrhosis evaluated for liver transplantation.

Recent findings

Several tools have been developed to further stratify risk of adverse events independent of liver disease severity. These include tests of disability such as activities of daily living and the Karnofsky Performance Score as well as tests of physical frailty such as the Liver Frailty Index (hand-grip, chair stands, and balance).

Summary

Increasingly, the frailty assessment is seen as a critical component of the liver transplant evaluation. Further research is needed to clarify the optimal timing of testing and the implications of longitudinal change.

Exercise in cirrhosis: Translating evidence and experience to practice

Physical inactivity, sarcopenia, and frailty are highly prevalent, independent predictors of morbidity and mortality in patients with cirrhosis. Across a range of chronic diseases, exercise training is a key recommendation supported by guidelines and, for some conditions, even by governmental funding of exercise programmes. Consistent with the broader chronic disease literature, the evidence for a benefit of exercise in cirrhosis is promising. Several small trials have reported significant improvements in muscle health (mass, strength, functional capacity), quality of life, fatigue, and reductions in the hepatic venous pressure gradient, without adverse events. With strong emerging evidence surrounding the substantial risks of sarcopenia/frailty and our first-hand experiences with liver pre-transplant exercise programmes, we contend that routine patient care in cirrhosis should include an exercise prescription. Some clinicians may lack the resources and necessary background to translate the existing evidence into a practicable intervention. Our team, comprised of physiotherapists, exercise physiologists, hepatologists, transplant specialists, and knowledge translation experts from six North American centres, has distilled the essential background information, tools, and practices into a set of information ready for immediate implementation into clinics ranging from a family practice setting to specialty cirrhosis clinics. Augmenting the rationale and evidence are supplementary materials including video and downloadable materials for both patients and the physician. Supporting the exercising patient is a section regarding information about nutrition, providing practical tips suitable for all patients with cirrhosis.

Elevated alveolar nitric oxide is linked to poor aerobic capacity and chronotropic incompetence in liver transplant candidates

BACKGROUND & AIMS

Increased nitric oxide is involved in abnormal hemodynamic parameters and respiratory function of cirrhotic patients. We aimed to quantify partitioning exhaled nitric oxide measurements in exhaled air in liver transplantation (LT) candidates and evaluate their relationships with chronotropic incompetence and aerobic capacity.

METHODS

We compared exhaled nitric oxide (NO) measurements, heart rate response and peak oxygen uptake during incremental exercise in liver transplantation candidates to those of controls.

RESULTS

As opposed to healthy control subjects, LT candidates displayed elevated alveolar NO, blunted chronotropic response and reduced V'O₂ at maximal exercise. In LT candidates, median peak V'O₂ was 18.7 ml kg^-1 min^-1 (interquartile range (IQR) 16.2; 21.8), corresponding to 65% (IQR 57; 72) of the predicted value. Compared with controls, LT candidates had increased levels of alveolar NO (median (IQR) 2.0 (1.2; 2.2) versus 3.1 (2.3; 4.5), p < 0.001). In controls, no relations were found between alveolar NO and V'O₂ peak or heart rate reserve whereas in cirrhotic patients, negative correlations and negative slopes were found between alveolar NO and V'O₂ peak and heart rate reserve decrease.

CONCLUSIONS

Increasing alveolar NO could be a specific pathophysiological condition limiting aerobic capacity in LT candidates.

Home Exercise Training Improves Exercise Capacity in Cirrhosis Patients: Role of Exercise Adherence

Cirrhosis patients have reduced peak aerobic power (peak VO₂) that is associated with reduced survival. Supervised exercise training increases exercise tolerance. The effect of home-based exercise training (HET) in cirrhosis is unknown. The objective was to evaluate the safety and efficacy of 8 weeks of HET on peak VO₂, 6-minute walk distance (6MWD), muscle mass, and quality of life in cirrhosis. Random assignment to 8 weeks of HET (moderate to high intensity cycling exercise, 3 days/week) or usual care. Exercise adherence defined as completing ≥80% training sessions. Paired t-tests and analysis of covariance used for comparisons. Forty patients enrolled: 58% male, mean age 57 y, 70% Child Pugh-A. Between group increases in peak VO₂ (1.7, 95% CI: −0.33 to 3.7 ml/kg/min, p = 0.09) and 6MWD (33.7, 95% CI: 5.1 to 62.4 m, p = 0.02) were greater after HET versus usual care. Improvements even more marked in adherent subjects for peak VO₂ (2.8, 95% CI: 0.5–5.2 mL/kg/min, p = 0.02) and 6MWD (46.4, 95% CI: 12.4–80.5 m, p = 0.009). No adverse events occurred during testing or HET. Eight weeks of HET is a safe and effective intervention to improve exercise capacity in cirrhosis, with maximal benefits occurring in those who complete ≥80% of the program.

Nutrition and the transplant candidate

Cirrhosis is the most common indication for liver transplantation (LT) worldwide. Malnutrition is present in at least two-thirds of patients with cirrhosis awaiting LT. It negatively impacts survival, quality of life, and the ability to respond to stressors, such as infection and surgery. Muscle wasting or sarcopenia is the most objective feature of chronic protein malnutrition in cirrhosis, and this condition is associated with increased morbidity and mortality before and after LT. In addition to its objectivity, muscularity assessment with cross-sectional imaging studies is a useful marker of nutritional status in LT candidates, as sarcopenia reflects a chronic decline in the general physical condition, rather than acute severity of the liver disease. Despite the high prevalence and important prognostic role, malnutrition and sarcopenia are frequently overlooked because standards for nutritional assessment are lacking and challenges such as fluid retention and obesity are prevalent. In this review, current diagnostic methods to evaluate malnutrition, including muscle abnormalities in cirrhosis, are discussed and current knowledge regarding the incidence and clinical impact of malnutrition in cirrhosis and its impact after LT are presented. Existing and potential novel therapeutic strategies for malnutrition in cirrhosis are also discussed, emphasizing the treatment of muscle wasting in the LT candidate in an effort to improve survival while waiting for LT and to reduce morbidity and mortality after LT.Liver Transplantation 23 1451-1464 2017 AASLD.