Impact of Obesity on Heart Transplantation Outcomes

International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024

The "International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024" updates and replaces the "Listing Criteria for Heart Transplantation: International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates-2006" and the "2016 International Society for Heart Lung Transplantation Listing Criteria for Heart Transplantation: A 10-year Update." The document aims to provide tools to help integrate the numerous variables involved in evaluating patients for transplantation, emphasizing updating the collaborative treatment while waiting for a transplant. There have been significant practice-changing developments in the care of heart transplant recipients since the publication of the International Society for Heart and Lung Transplantation (ISHLT) guidelines in 2006 and the 10-year update in 2016. The changes pertain to 3 aspects of heart transplantation: (1) patient selection criteria, (2) care of selected patient populations, and (3) durable mechanical support. To address these issues, 3 task forces were assembled. Each task force was cochaired by a pediatric heart transplant physician with the specific mandate to highlight issues unique to the pediatric heart transplant population and ensure their adequate representation. This guideline was harmonized with other ISHLT guidelines published through November 2023. The 2024 ISHLT guidelines for the evaluation and care of cardiac transplant candidates provide recommendations based on contemporary scientific evidence and patient management flow diagrams. The American College of Cardiology and American Heart Association modular knowledge chunk format has been implemented, allowing guideline information to be grouped into discrete packages (or modules) of information on a disease-specific topic or management issue. Aiming to improve the quality of care for heart transplant candidates, the recommendations present an evidence-based approach.

Impact of Donor-Recipient BMI Ratio on Survival Outcomes of Heart Transplant Recipients: A Retrospective Analysis Study

OBJECTIVE

This study aimed to investigate the impact of the donor-recipient BMI ratio on the survival outcomes of heart transplant recipients.

METHODS

A retrospective analysis was conducted on 641 heart transplant patients who underwent surgery between September 2008 and June 2021. The BMI ratio (donor BMI divided by recipient BMI) was calculated for each patient. Kaplan-Meier survival analysis and Cox proportional hazards regression were performed to evaluate survival rates and determine the hazard ratio (HR) for mortality.

RESULTS

Significant differences were found in donor age and donor-recipient height ratio between the BMI ratio groups. The BMI ratio ≥ 1 group had a higher mean donor age (37.27 ± 10.54 years) compared to the BMI ratio < 1 group (34.72 ± 11.82 years, p = 0.008), and a slightly higher mean donor-recipient height ratio (1.02 ± 0.06 vs. 1.00 ± 0.05, p = 0.002). The Kaplan-Meier survival analysis indicated that the survival rate in the BMI ratio ≥ 1 group was significantly lower than in the BMI ratio < 1 group. Cox multivariate analysis, adjusted for confounding factors, revealed a HR of 1.50 (95% CI: 1.08-2.09) for mortality in patients with a BMI ratio ≥ 1. No significant differences were observed in ICU stay, postoperative hospitalization days, or total mechanical ventilation time between the groups.

CONCLUSION

A higher donor-recipient BMI ratio was associated with an increased risk of mortality in heart transplant recipients.

Pre-operative pectoralis muscle area index is associated with biomarkers of inflammation and endotoxemia and predicts clinical outcomes after left ventricular assist device implantation: A cohort study

BACKGROUND

Pre-left ventricular assist device (LVAD) pectoralis muscle assessment, an estimate of sarcopenia, has been associated with postoperative mortality and gastrointestinal bleeding, though its association with inflammation, endotoxemia, length-of-stay (LOS), and readmissions remains underexplored.

METHODS

This was a single-center cohort study of LVAD patients implanted 1/2015-10/2018. Preoperative pectoralis muscle area was measured on chest computed tomography (CT), adjusted for height squared to derive pectoralis muscle area index (PMI). Those with PMI in the lowest quintile were defined as low-PMI cohort; all others constituted the reference cohort. Biomarkers of inflammation (interleukin-6, adiponectin, tumor necrosis factor-α [TNFα]) and endotoxemia (soluble (s)CD14) were measured in a subset of patients.

RESULTS

Of the 254 LVAD patients, 95 had a preoperative chest CT (median days pre-LVAD: 7 [IQR 3-13]), of whom 19 (20.0%) were in the low-PMI cohort and the remainder were in the reference cohort. Compared with the reference cohort, the low-PMI cohort had higher levels of sCD14 (2594 vs. 1850 ng/mL; p = 0.04) and TNFα (2.9 vs. 1.9 pg/mL; p = 0.03). In adjusted analyses, the low-PMI cohort had longer LOS (incidence rate ratio 1.56 [95% confidence interval 1.16-2.10], p = 0.004) and higher risk of 90-day and 1-year readmissions (subhazard ratio 5.48 [1.88-16.0], p = 0.002; hazard ratio 1.73 [1.02-2.94]; p = 0.04, respectively).

CONCLUSIONS

Pre-LVAD PMI is associated with inflammation, endotoxemia, and increased LOS and readmissions.

The association between body mass index, exercise capacity, and health-related quality of life in heart transplant recipients

Introduction

Pre-transplant obesity and weight gain after heart transplantation are both associated with increased risk of poor clinical outcomes. We aimed to assess the association between overweight or obesity, exercise capacity, and health-related quality of life in heart transplant recipients.

Methods

This study is based on baseline data from the IronIC trial, in which we randomized 102 heart transplant recipients with iron deficiency to ferric derisomaltose or placebo. We performed cardio pulmonary exercise testing in all participants. To assess quality of life, we used the SF-36v2 questionnaire, using two sum scores: the physical component summary and the mental component summary. A minimal clinically important difference was defined as ≥2 and ≥3 for the physical and the mental component summary, respectively.

Results

24/102 heart transplant recipients (24%) had a body mass index (BMI) ≥30 kg/m2. Peak oxygen consumption was 17.3 ± 4.6 ml/kg/min in the obese group vs. 24.7 ± 6.4 ml/kg/min in the group with a BMI <30 for a between-group difference of 7.4 (95% confidence interval 4.7-10.2) ml/kg/min: p < 0.001. The physical component summary score was on average 5.2 points lower in the patients with a body mass index ≥30 than in the lower weight group (p = 0.04).

Conclusion

Almost a quarter of our heart transplant recipients in long-term follow-up had a BMI ≥30 kg/m2. These patients had substantially lower exercise capacity and lower quality of life in the physical domain.

Acute Kidney Injury After Heart Transplantation: Risk Factors and Clinical Outcomes

OBJECTIVE

Acute kidney injury (AKI) requiring renal-replacement therapy (RRT) after heart transplantation (OHT) is common and impairs outcomes. This study aimed to identify independent donor and recipient risk factors associated with RRT after OHT.

DESIGN

A retrospective data analysis.

SETTING

Data were collected from clinical routines in a maximum-care university hospital.

PARTICIPANTS

Patients who underwent OHT.

INTERVENTIONS

The authors retrospectively analyzed data from 264 patients who underwent OHT between 2012 and 2021; 189 patients were eligible and included in the final analysis.

MEASUREMENTS AND MAIN RESULTS

The mean age was 48.0 ± 12.3 years, and 71.4% of patients were male. Ninety (47.6%) patients were on long-term mechanical circulatory support (lt-MCS). Posttransplant AKI with RRT occurred in 123 (65.1%) patients. In a multivariate analysis, preoperative body mass index >25 kg/m² (odds ratio [OR] 4.74, p < 0.001), elevated preoperative creatinine levels (OR for each mg/dL increase 3.44, p = 0.004), administration of red blood cell units during transplantation procedure (OR 2.31, p = 0.041) and ischemia time (OR for each hour increase 1.77, p = 0.004) were associated with a higher incidence of RRT. The use of renin-angiotensin-aldosterone system blockers before transplantation was associated with a reduced risk of RRT (OR 0.36, p = 0.013). The risk of mortality was 6.9-fold higher in patients who required RRT (hazard ratio 6.9, 95% CI: 2.1-22.6 p = 0.001). Previous lt-MCS, as well as donor parameters, were not associated with RRT after OHT.

CONCLUSIONS

The implementation of guideline-directed medical therapy, weight reduction, minimizing ischemia time (ie, organ perfusion systems, workflow optimization), and comprehensive patient blood management potentially influences renal function and outcomes after OHT.

Temporary Mechanical Circulatory Support During Bariatric Surgery: A Novel Bridge to Durable Left Ventricular Assist Device and Cardiac Transplantation

Advanced heart failure (HF) with comorbid severe obesity presents a unique surgical dilemma: bariatric surgery may help patients meet cardiac transplantation body mass index (BMI) criteria, but poor cardiac function puts them at increased intraoperative risk. Per International Society for Heart and Lung Transplantation (ISHLT) guidelines BMI > 35 is a contraindication for orthotopic heart transplantation. Temporary mechanical circulatory support (MCS) with Impella 5.5 during bariatric surgery, as presented in this report, may help solve this dilemma for some patients. We present three patients with severe obesity and advanced heart failure (HF) who underwent successful bariatric surgery while supported by Impella 5.5 (Abiomed, Inc., Danvers, MA).

The impact of obesity and LVAD-bridging on heart transplant candidate outcomes: a linked STS INTERMACS - OPTN/UNOS data analysis

BACKGROUND

Limited data integrating waitlist and postheart transplant (HT) mortality have evaluated outcomes of left ventricular assist device (LVAD)-bridged strategy vs no LVAD according to patient characteristics. We evaluated waitlist and post-HT mortality in LVAD-bridged vs nonbridged patients based on body mass index (BMI).

METHODS

We included linked adults listed for HT in Organ Procurement and Transplant Network/United Network for Organ Sharing and patients receiving durable LVAD as bridge to HT or candidacy in Society of Thoracic Surgeons/Interagency Mechanical Circulatory Support databases (2010-2019). Using BMI at listing or LVAD implant, we categorized patients as underweight (<18.5 kg/m2), normal weight (18.5-24.99 kg/m2), overweight (25-29.99 kg/m2), and obese (≥30 kg/m2). Kaplan-Meier analysis and multivariable Cox proportional hazards models informed the effect of LVAD-bridged and nonbridged strategy by BMI on waitlist, post-HT, and overall mortality (including waitlist and post-HT mortality).

RESULTS

Among 11,216 LVAD-bridged and 17,122 nonbridged candidates, bridged candidates were more frequently obese (37.3% vs 28.6%) (p < 0.001). Multivariable analysis indicated increased waitlist mortality in LVAD-bridged vs nonbridged with overweight (Hazard ratio (HR) 1.18, 95% confidence interval (CI) 1.02-1.36) or obesity (HR 1.35, 95%CI 1.17-1.56) in comparison to normal weight candidates (HR 1.02, 95%CI 0.88-1.19) (p-interaction < 0.001). Post-transplant mortality was not statistically different in LVAD-bridged vs nonbridged patients across BMI categories (p-interaction = 0.26). There was a nonsignificant graded increase in overall mortality in LVAD-bridged with overweight (HR 1.53, 95%CI 1.39-1.68) or obesity (HR 1.61, 95%CI 1.46-1.78) compared to nonbridged patients (p-interaction = 0.13).

CONCLUSIONS

LVAD-bridged candidates with obesity had higher waitlist mortality compared to nonbridged candidates with obesity. Post-transplant mortality was similar in LVAD-bridged and nonbridged patients, but obesity remained associated with increased mortality in both groups. This study may aid clinicians and advanced heart failure patients with obesity in decision-making.

Efficacy of bariatric intervention as a bridge to cardiac transplant

BACKGROUND

Many patients with heart failure (HF) are denied cardiac transplants due to inability to meet transplantation body mass index (BMI) criteria. Bariatric intervention, including surgery, medication, and weight loss guidance, may help patients lose weight and become eligible for transplantation.

OBJECTIVE

We aim to contribute to the literature on the safety and efficacy of bariatric intervention on patients with obesity and HF who are awaiting cardiac transplantation.

SETTING

University hospital, United States.

METHODS

This was a mixed retrospective/prospective study. Eighteen patients with HF and BMI >35 kg/m2 were reviewed. Patients were divided based on whether they underwent bariatric surgery or nonsurgical intervention and whether they had left ventricular assist devices or other advanced heart failure therapy including inotropic support, guideline-directed medical therapy, and/or temporary mechanical circulatory support. Weight, BMI, and left ventricular ejection fraction (LVEF) were collected before bariatric intervention and 6 months after bariatric intervention.

RESULTS

No patients were lost to follow-up. Bariatric surgery led to statistically significant decreases in weight and BMI when compared with nonsurgical patients. At 6 months after intervention, surgical patients lost an average of 18.6 kg and decreased their BMI by 6.4 kg/m2 while nonsurgical patients lost 1.9 kg and decreased their BMI by .7 kg/m2. After bariatric intervention, surgical patients had an average LVEF increase of 5.9% and nonsurgical patients had an average decrease of 5.9%, although these findings lacked statistical significance.

CONCLUSION

Our study suggests that bariatric intervention among patients with HF and obesity is a safe and effective method of weight and BMI reduction.

Association of Size Matching Using Predicted Heart Mass With Mortality in Heart Transplant Recipients With Obesity or High Pulmonary Vascular Resistance

Importance

Pretransplant obesity and higher pulmonary vascular resistance (PVR) are risk factors for death after heart transplant. However, it remains unclear whether appropriate donor-to-recipient size matching using predicted heart mass (PHM) is associated with lower risk.

Objective

To investigate the association of size matching using PHM with risk of death posttransplant among patients with obesity and/or higher PVR.

Design, Setting, and Participants

All adult patients (>18 years) who underwent heart transplant between 2003 and 2022 with available information using the United Network for Organ Sharing cohort database. Multivariable Cox models and multivariable-adjusted spline curves were used to examine the risk of death posttransplant with PHM matching. Data were analyzed from October 2022 to March 2023.

Exposure

Recipient's body mass index (BMI) in categories (<18.0 [underweight], 18.1-24.9 [normal weight, reference], 25.0-29.9 [overweight], 30.0-34.9 [obese 1], 35-39.9 [obese 2], and ≥40.0 [obese 3]) and recipient's pretransplant PVR in categories of less than 4 (29 061 participants), 4 to 6 (2842 participants), and more than 6 Wood units (968 participants); and less than 3 (24 950 participants), 3 to 5 (6115 participants), and 5 or more (1806 participants) Wood units.

Main Outcome

All-cause death posttransplant on follow-up.

Results

The mean (SD) age of the cohort of 37 712 was 52.8 (12.8) years, 27 976 (74%) were male, 25 342 were non-Hispanic White (68.0%), 7664 were Black (20.4%), and 3139 were Hispanic or Latino (8.5%). A total of 12 413 recipients (32.9%) had a normal BMI, 13 849 (36.7%) had overweight, and 10 814 (28.7%) had obesity. On follow-up (median [IQR] 5.05 [0-19.4] years), 12 785 recipients (3046 female) died. For patients with normal weight, overweight, or obese 2, receiving a PHM-undermatched heart was associated with an increased risk of death (normal weight hazard ratio [HR], 1.20; 95% CI, 1.07-1.34; overweight HR, 1.12; 95% CI, 1.02-1.23; and obese 2 HR, 1.07; 95% CI, 1.01-1.14). Moreover, patients with higher pretransplant PVR who received an undermatched heart had a higher risk of death posttransplant in multivariable-adjusted spline curves in graded fashion until appropriately matched. In contrast, risk of death among patients receiving a PHM-overmatched heart did not differ from the appropriately matched group, including in recipients with an elevated pretransplant PVR.

Conclusion and Relevance

In this cohort study, undermatching donor-to-recipient size according to PHM was associated with higher posttransplant mortality, specifically in patients with normal weight, overweight, or class II obesity and in patients with elevated pretransplant PVR. Overmatching donor-to-recipient size was not associated with posttransplant survival.

Prolonged waitlisting is associated with mortality in extracorporeal membrane oxygenation-supported heart transplantation candidates

OBJECTIVE

Heart transplantation (HTx) candidates supported with venoarterial extracorporeal membrane oxygenation (ECMO) may be listed at highest status 1 but are at inherent risk for ECMO-related complications. The effect of waitlist time on postlisting survival remains unclear in candidates with ECMO support who are listed using the new allocation system.

METHODS

Adult candidates listed with ECMO for a first-time, single-organ HTx from October 18, 2018, to March 21, 2021, in the Scientific Registry of Transplant Recipients database were included and stratified according to waitlist time (≤7 vs ≥8 days). Postlisting outcomes were compared between cohorts.

RESULTS

Among 175 candidates waitlisted for ≤7 days, 162 (92.6%) underwent HTx whereas 13 (7.4%) died/deteriorated compared with 41 (57.8%) and 21 (29.6%) of the 71 candidates waitlisted for ≥8 days, respectively (P < .01). Blood type O candidates (odds ratio [OR], 2.94; 95% CI, 1.54-5.61) were more likely to wait ≥8 days whereas candidates with concurrent intra-aortic balloon pump were less likely (OR, 0.30; 95% CI, 0.10-0.89). Obesity was additionally associated among those listed at status 1 (OR, 2.04; 95% CI, 1.00-4.17). Waitlisting for ≥8 days was independently associated with 90-day postlisting mortality conditional on survival to day 8 postlisting (hazard ratio, 5.59; 95% CI, 2.59-12.1). Candidates listed at status 1 showed similar trends (hazard ratio, 5.49; 95% CI, 2.39-12.6). There was no significant difference in 90-day post-HTx survival depending on whether a candidate waited for ≥8 days versus ≤7 days (92.7 vs 92.0%; log rank P = .87).

CONCLUSIONS

Among ECMO-supported candidates, obtaining HTx within 1 week of listing might improve overall survival.

Validation of days alive and out of hospital as a new patient-centered outcome to quantify life impact after heart transplantation

The number of patients waiting for heart transplantation (HTX) is increasing. Thus, identification of outcome-relevant factors is crucial. This study aimed to identify perioperative factors associated with days alive and out of hospital (DAOH)-a patient-centered outcome to quantify life impact-after HTX. This retrospective cohort study screened 187 patients who underwent HTX at university hospital Duesseldorf, Germany from September 2010 to December 2020. The primary endpoint was DAOH at 1 year. Risk factors for mortality after HTX were assessed in univariate analysis. Variables with significant association were entered into multivariable quantile regression. In total, 175 patients were included into analysis. Median DAOH at 1 year was 295 (223-322) days. In univariate analysis the following variables were associated with reduced DAOH: recipient or donor diabetes pre-HTX, renal replacement therapy (RRT), VA-ECMO therapy, recipient body mass index, recipient estimated glomerular filtration rate (eGFR) and postoperative duration of mechanical ventilation. After adjustment, mechanical ventilation, RRT, eGFR and recipient diabetes showed significant independent association with DAOH. This study identified risk factors associated with reduced DAOH at 1-year after HTX. These findings might complement existing data for outcome of patients undergoing HTX.

Machine learning and artificial intelligence in cardiac transplantation: A systematic review

Background

This review aims to systematically evaluate the currently available evidence investigating the use of artificial intelligence (AI) and machine learning (ML) in the field of cardiac transplantation. Furthermore, based on the challenges identified we aim to provide a series of recommendations and a knowledge base for future research in the field of ML and heart transplantation.

Methods

A systematic database search was conducted of original articles that explored the use of ML and/or AI in heart transplantation in EMBASE, MEDLINE, Cochrane database, and Google Scholar, from inception to November 2021.

Results

Our search yielded 237 articles, of which 13 studies were included in this review, featuring 463 850 patients. Three main areas of application were identified: (1) ML for predictive modeling of heart transplantation mortality outcomes; (2) ML in graft failure outcomes; (3) ML to aid imaging in heart transplantation. The results of the included studies suggest that AI and ML are more accurate in predicting graft failure and mortality than traditional scoring systems and conventional regression analysis. Major predictors of graft failure and mortality identified in ML models were: length of hospital stay, immunosuppressive regimen, recipient's age, congenital heart disease, and organ ischemia time. Other potential benefits include analyzing initial lab investigations and imaging, assisting a patient with medication adherence, and creating positive behavioral changes to minimize further cardiovascular risk.

Conclusion

ML demonstrated promising applications for improving heart transplantation outcomes and patient‐centered care, nevertheless, there remain important limitations relating to implementing AI into everyday surgical practices.