Functional status of United States children supported with a left ventricular assist device at heart transplantation

Poor functional status at the time of waitlist for pediatric lung transplant is associated with worse pretransplant outcomes

BACKGROUND

Whether functional status is associated with survival to pediatric lung transplant is unknown. We hypothesized that completely dependent functional status at waitlist registration, defined using Lansky Play Performance Scale (LPPS), would be associated with worse outcomes.

METHODS

Retrospective cohort study of pediatric lung transplant registrants utilizing United Network for Organ Sharing's Standard Transplant Analysis and Research files (2005-2020). Primary exposure was completely dependent functional status, defined as LPPS score of 10-40. Primary outcome was waitlist removal for death/deterioration with cause-specific hazard ratio (CSHR) regression. Subdistribution hazard regression (SHR, Fine and Gray) was used for the secondary outcome of waitlist removal due to transplant/improvement with a competing risk of death/deterioration. Confounders included: sex, age, race, diagnosis, ventilator dependence, extracorporeal membrane oxygenation, year, and listing center volume.

RESULTS

A total of 964 patients were included (63.5% ≥ 12 years, 50.2% cystic fibrosis [CF]). Median waitlist days were 95; 20.1% were removed for death/deterioration and 68.2% for transplant/improvement. Completely dependent functional status was associated with removal due to death/deterioration (adjusted CSHR 5.30 [95% CI 2.86-9.80]). This association was modified by age (interaction p = 0.0102), with a larger effect for age ≥12 years, and particularly strong for CF. In the Fine and Gray model, completely dependent functional status did not affect the risk of removal due to transplant/improvement with a competing risk of death/deterioration (adjusted SHR 1.08 [95% CI 0.77-1.49]).

CONCLUSIONS

Pediatric lung transplant registrants with the worst functional status had worse pretransplant outcomes, especially for adolescents and CF patients. Functional status at waitlist registration may be a modifiable risk factor to improve survival to lung transplant.

Functional status predicts pediatric heart transplant outcomes: A united network for organ sharing (UNOS) database study

BACKGROUND

Functional status predicts waitlist survival in adult heart transplantation and is an independent predictor of outcomes in pediatric liver transplantation. This has not been studied in pediatric heart transplantation. Study aims were to determine the association of: (1) functional status at listing with waitlist and post-transplant outcomes, and (2) functional status at transplant with post-transplant outcomes in pediatric heart transplantation.

METHODS

Retrospective United Network of Organ Sharing database study of pediatric patients listed for heart transplant between 2005 and 2019 with Lansky Play Performance Scale (LPPS) scores at listing. Standard statistical methods were used to assess relationships between LPPS and outcomes (waitlist and post-transplant). Negative waitlist outcome was defined as death or removal from waitlist due to clinical deterioration.

RESULTS

There were 4,169 patients identified, including 1,080 with LPPS 80-100 (normal activity), 1,603 with LPPS 50-70 (mild limitations), and 1,486 with LPPS 10-40 (severe limitations). LPPS 10-40 correlated with negative waitlist outcomes (HR 1.69, CI 1.59-1.80, p < 0.0001). While LLPS at listing had no association with post-transplant survival, those with LPPS 10-40 at transplant had inferior 1-year post-transplant survival compared to those with LPPS ≥50 (92% vs 95%-96%, p = 0.0011). Functional status was an independent predictor of post-transplant outcomes in patients with cardiomyopathy. A functional improvement of ≥20 points between listing and transplant (N = 770, 24%) was associated with higher 1-year post-transplant survival (HR 1.63, 95% CI: 1.10-2.41, p = 0.018).

CONCLUSIONS

Functional status is associated with waitlist and post-transplant outcomes. Interventions targeting functional impairment may improve pediatric heart transplantation outcomes.

Safety and Feasibility of Exercise Rehabilitation in Children with Ventricular Assist Devices

Children with advanced heart failure may require ventricular assist devices (VAD) while awaiting heart transplantation. Currently, no data exist regarding the safety of exercise rehabilitation (ER) in children on VAD support. The purpose of this study was to determine the safety and feasibility of ER in children on VAD support awaiting heart transplantation. Eligible patients underwent VAD placement between 1998 and 2019; both inpatient and outpatient participants were included. After VAD implantation and when ambulatory, patients were enrolled in ER. Exercise sessions were scheduled three times a week and consisted of aerobic and musculoskeletal conditioning. A total of 29 patients (59% male, mean age 14 ± 3.2 years) were included with a median VAD duration of 120 ± 109 days. Cardiac diagnoses included cardiomyopathy (81%) and congenital heart disease (19%). VAD type included pulsatile (59%) and continuous-flow devices (41%). Eight hundred and sixty-four (85%) ER sessions were successfully completed and began at a mean of 49 days (range 19-108) after VAD implant. No adverse events, including episodes of hypotension, significant complex arrhythmia, or VAD malfunction occurred during exercise testing or ER, and no sessions were discontinued prematurely. Pediatric patients on VAD support can safely participate in ER with relatively high compliance, and sessions can be implemented early after VAD implantation. Given the safety profile, ER in pediatric VAD recipients, which is a modifiable pre-transplant risk factor that may improve functional capacity, warrants further study as a potential modality to improve post-transplant outcomes.

Variation in Cardiac Rehabilitation for Pediatric Ventricular Assist Device Recipients Across North America

Despite increasing utilization of continuous-flow pediatric ventricular assist devices (VAD) in children, data on exercise testing and cardiac rehabilitation (CR) are unknown. We described variation in CR practices and identified barriers to exercise testing and CR. A survey was performed through the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) representing pediatric VAD centers across North America. Descriptive statistics were performed. A multidisciplinary cohort of 52 respondents from 28 pediatric VAD centers responded. Although 38% reported performing exercise testing, most (65%) used 6 minute walk tests rather than formal cycle or treadmill exercise testing. While all respondents refer to physical therapy during the initial inpatient stay for VAD placement, only 52% refer to a CR program. When performed, CR was performed at an ACTION center (84%), a local specialized center (21%), or a home-based CR program (26%). Commonly cited barriers to either CR or exercise testing were inadequate resources, inadequate implementation logistics knowledge, concerns about safety, inability of patients to travel to a CR facility, and concern about utility of exercise testing or CR. Over 90% of centers were interested in implementing a standardized pediatric VAD CR program. Utilization of exercise testing and CR after VAD placement is variable. Despite perceived barriers, most pediatric VAD centers are interested in implementing a standardized CR program for recipients. In response to this interest, we plan to implement a standardized CR protocol to all ACTION pediatric VAD centers in an effort to improve pretransplant waitlist rehabilitation and post-transplant outcomes.

Functional status at listing predicts waitlist and posttransplant mortality in pediatric liver transplant candidates

Functional impairment is associated with mortality in adult liver transplant candidates. This has not been studied in pediatric liver transplant candidates. United Network for Organ Sharing Standard Transplant Analysis and Research files were used to investigate functional status, waitlist mortality, and posttransplant outcomes in children younger than 18 years who were waitlisted in 2006-2016 for primary liver transplant. Functional status was categorized, by using the Lansky Play-Performance Scale (LPPS), as normal/good (80-100), moderately impaired (50-70), or severely impaired (10-40) by center assessment. Among 3250 children not listed as Status 1A, 62% had an LPPS score of 80-100, 25% had a score of 50-70, and 13% had a score of 10-40 at listing. Children with an LPPS score of 10-40 at listing were more likely to die while on the waitlist (standardized hazard ratio 1.85, 95% confidence interval 1.09-3.13, P = .02) in analyses adjusting for being on a ventilator, breathing support, or dialysis and other illness severity measures. For the 2565 children transplanted, an LPPS score of 10-40 at listing drastically increased mortality risk by 1 year posttransplant (hazard ratio 5.77, 95% confidence interval 3.05-10.91, P < .0005). LPPS scores of 10-40 and 50-70 both increased the risk of graft loss by 1 year. Functional status is an independent predictor of waitlist and posttransplant mortality in pediatric liver transplant candidates. Validated tools for the assessment of functional status in these children would improve our ability to predict mortality risk-and to appropriately prioritize them for transplant.

Impact of ventricular assist device implantation on the nutritional status of children awaiting heart transplantation

BACKGROUND

Malnutrition is common in pediatric heart failure and is associated with mortality. The effect of VAD support on malnutrition in children is unknown. We sought to compare the prevalence and severity of malnutrition at HT in children on VAD support vs OMT to inform decisions regarding support strategies.

METHODS

Retrospective chart review involving all patients <18 years who underwent HT at Stanford between 1/1/2011 and 3/1/2018. Malnutrition diagnosis and severity were defined by ASPEN guidelines using the lowest age-adjusted z-score for weight (WAZ), height (HAZ), and BMI (BMIZ) when the patient was euvolemic. Changes in z-scores from baseline to HT and across groups were analyzed.

RESULTS

A total of 104 patients (52 in each group) were included. Among all patients, WAZ (-0.9 vs 0.3, P < 0.001) and BMIZ (0 vs 0.6, P < 0.001) improved while HAZ (-0.9 vs -0.9, P = 0.4) did not. Compared to children on OMT, children on VAD experienced greater increases in WAZ (0.8 vs 0.3, P < 0.001) and BMIZ (0.7 vs 0.2, P < 0.003) at HT. The prevalence of moderate-to-severe malnutrition decreased in VAD patients (40% to 19%, P < 0.001) and increased in OMT patients (37% to 46%, P < 0.001), leading to a lower prevalence of moderate-to-severe malnutrition at HT (19% vs 46%, P = 0.003).

CONCLUSIONS

Malnutrition is common in pediatric HT candidates. Compared to children on OMT, children on VAD support had greater improvement in nutritional status while awaiting HT, and a lower prevalence of malnutrition at HT.