Impact of age on incidence and prevalence of moderate-to-severe cellular rejection detected by routine surveillance biopsy in pediatric heart transplantation

Serial assessment of right ventricular function can detect acute cellular rejection in children with heart transplantation

BACKGROUND

Echocardiographic markers of ACR are essential for early recognition and management. The literature's primary focus has been on the LV with little attention given to the RV. This study aimed to investigate echocardiographic right ventricular indices in the detection of ACR and to evaluate their utility as prognostic indicators of graft integrity.

METHODS

We performed a retrospective chart review of children with biopsy-proven ACR following orthotopic heart transplant and an echocardiogram within 24 h of biopsy. Selected echocardiographic markers were compared at baseline, during ACR, and at follow-up.

RESULTS

Forty-eight patients (56% male) had a total of 84 ACR episodes. Decrease in RV FAC (mean - 17.1%, p < .001) and TAPSE (mean - 8.9%, p < .001) with increase in left ventricular posterior wall thickness in diastole and systole (LVPWTd) (mean + 9.0%, p = .012) and LVPWTs (mean + 8.3%, p = .016) were found during ACR. Interestingly, these parameters improved following the episode of rejection. Additionally, these markers were compared after recovery between children with and without graft failure. RV dysfunction (FAC and TAPSE) and changes in LV posterior wall thickness were not found to have prognostic significance for graft integrity in children with heart transplantation.

CONCLUSIONS

RV echocardiographic functional parameters should be considered as valuable adjuncts in rejection surveillance. Further, the presence of RV dysfunction does not have prognostic significance for graft integrity but is reversible as ongoing damage was not detectable by such.

Rejection surveillance in pediatric heart transplant recipients: Critical reflection on the role of frequent and long-term routine surveillance endomyocardial biopsies and comprehensive review of non-invasive rejection screening tools

BACKGROUND

Despite significant medical advances in the field of pediatric heart transplantation (HT), acute rejection remains an important cause of morbidity and mortality. Endomyocardial biopsy (EMB) remains the gold-standard method for diagnosing rejection but is an invasive, expensive, and stressful process. Given the potential adverse consequences of rejection, routine post-transplant rejection surveillance protocols incorporating EMB are widely employed to detect asymptomatic rejection. Each center employs their own specific routine rejection surveillance protocol, with no consensus on the optimal approach and with high inter-center variability. The utility of high-frequency and long-term routine surveillance biopsies (RSB) in pediatric HT has been called into question.

METHODS

Sources for this comprehensive review were primarily identified through searches in biomedical databases including MEDLINE and Embase.

RESULTS

The available literature suggests that the diagnostic yield of RSB is low beyond the first year post-HT and that a reduction in RSB intensity from high-frequency to low-frequency can be done safely with no impact on early and mid-term survival. Though there are emerging non-invasive methods of detecting asymptomatic rejection, the evidence is not yet strong enough for any test to replace EMB.

CONCLUSION

Overall, pediatric HT centers in North America should likely be doing fewer RSB than are currently performed. Risk factors for rejection should be considered when designing the optimal rejection surveillance strategy. Noninvasive testing including emerging biomarkers may have a complementary role to aid in safely reducing the need for RSB.

Impact of institutional routine surveillance endomyocardial biopsy frequency in the first year on rejection and graft survival in pediatric heart transplantation

BACKGROUND

Routine surveillance biopsy (RSB) is performed to detect asymptomatic acute rejection (AR) after heart transplantation (HT). Variation in pediatric RSB across institutions is high. We examined center-based variation in RSB and its relationship to graft loss, AR, coronary artery vasculopathy (CAV), and cost of care during the first year post-HT.

METHODS

We linked the Pediatric Health Information System (PHIS) and Scientific Registry of Transplant Recipients (SRTR, 2002-2016), including all primary-HT aged 0-21 years. We characterized centers by RSB frequency (defined as median biopsies performed among recipients aged ≥12 months without rejection in the first year). We adjusted for potential confounders and center effects with mixed-effects regression analysis.

RESULTS

We analyzed 2867 patients at 29 centers. After adjusting for patient and center differences, increasing RSB frequency was associated with diagnosed AR (OR 1.15 p = 0.004), a trend toward treated AR (OR 1.09 p = 0.083), and higher hospital-based cost (US$390 315 vs. $313 248, p < 0.001) but no difference in graft survival (HR 1.00, p = 0.970) or CAV (SHR 1.04, p = 0.757) over median follow-up 3.9 years. Center RSB-frequency threshold of ≥2/year was associated with increased unadjusted rates of treated AR, but no association was found at thresholds greater than this.

CONCLUSION

Center RSB frequency is positively associated with increased diagnosis of AR at 1 year post-HT. Graft survival and CAV appear similar at medium-term follow-up. We speculate that higher frequency RSB centers may have increased detection of clinically less important AR, though further study of the relationship between center RSB frequency and differences in treated AR is necessary.

Outcomes of low-intensity biopsy surveillance for rejection in paediatric cardiac transplantation

BACKGROUND

Significant inter-centre variability in the intensity of endomyocardial biopsy surveillance for rejection following paediatric cardiac transplantation has been reported. Our aim was to determine if low-intensity biopsy surveillance with two scheduled biopsies in the first year would produce outcomes similar to published registry outcomes.

METHODS

A retrospective study of paediatric recipients transplanted between 2008 and 2014 using a low-intensity biopsy protocol consisting of two surveillance biopsies at 3 and 12-13 months in the first post-transplant year, then annually thereafter. Additional biopsies were performed based on echocardiographic and clinical surveillance. Excluded were recipients that were re-transplanted or multi-organ transplanted or were followed at another institution.

RESULTS

A total of 81 recipients in the first 13 months after transplant underwent an average of 2 (SD ± 1.3) biopsies, 24 ± 6.8 echocardiograms, and 17 ± 4.4 clinic visits per recipient. During the 13-month period, 19 recipients had 24 treated rejection episodes, with the first at an average of 2.8 months post-transplant. The 3-, 12-, 36-, and 60-month conditional on discharge graft survival were 100%, 98.8%, 98.8%, and 90.4%, respectively, comparable to reported figures in major paediatric registries. At a mean follow-up of 4.7 ± 2.1 years, four patients (4.9%) developed cardiac allograft vasculopathy, three (3.7%) developed a malignancy, and seven (8.6%) suffered graft loss.

CONCLUSION

Rejection surveillance with a low-intensity biopsy protocol demonstrated similar intermediate-term outcomes and safety measures as international registries up to 5 years post-transplant.

Long-term surveillance biopsy: Is it necessary after pediatric heart transplant?

Due to limited and conflicting data in pediatric patients, long-term routine surveillance endomyocardial biopsy (RSB) in pediatric heart transplant (HT) remains controversial. We sought to characterize the rate of positive RSB and determine factors associated with RSB-detected rejection. Records of patients transplanted at a single institution from 1995 to 2015 with >2 year of post-HT biopsy data were reviewed for RSB-detected rejections occurring >2 year post-HT. We illustrated the trajectory of significant rejections (ISHLT Grade ≥3A/2R) among total RSB performed over time and used multivariable logistic regression to model the association between time and risk of rejection. We estimated Kaplan-Meier freedom from rejection rates by patient characteristics and used the log-rank test to assess differences in rejection probabilities. We identified the best-fitting Cox proportional hazards regression model. In 140 patients, 86% did not have any episodes of significant RSB-detected rejection >2 year post-HT. The overall empirical rate of RSB-detected rejection >2 year post-HT was 2.9/100 patient-years. The percentage of rejection among 815 RSB was 2.6% and remained stable over time. Years since transplant remained unassociated with rejection risk after adjusting for patient characteristics (OR = 0.98; 95% CI 0.78-1.23; P = 0.86). Older age at HT was the only factor that remained significantly associated with risk of RSB-detected rejection under multivariable Cox analysis (P = 0.008). Most pediatric patients did not have RSB-detected rejection beyond 2 years post-HT, and the majority of those who did were older at time of HT. Indiscriminate long-term RSB in pediatric heart transplant should be reconsidered given the low rate of detected rejection.

Cost-effectiveness of the National Pediatric Heart Transplantation Program in Australia

OBJECTIVES

Cost data for pediatric heart transplantation are scarce. We examined hospital cost of the national pediatric heart transplantation program in Australia and assessed factors associated with increased costs.

METHODS

The hospital cost of all children who underwent heart transplantation at a national referral center between January 2003 and June 2015 and were followed more than 1 year was retrospectively analyzed. Lifetime follow-up costs were adjusted for quality of life and projected to life expectancy. All costs were reported in 2016 US dollars.

RESULTS

Of 70 children who underwent heart transplantation in the study period, 61 were followed more than 1 year after transplantation (mean, 4.3 ± 2.5 years). Mean cost of primary heart transplantation was $278,480 (95% confidence interval, 219,282-337,679) and did not change over time. Pretransplant mechanical circulatory support was required in 36% (22/61) of children. On multivariable analysis, greater admission costs were associated with ventricular assist device and pretransplant length of stay. Mean annual follow-up cost after discharge was $55,823 (95% confidence interval, 47,631-64,015) in the first year and $12,119 (95% confidence interval, 8578-15,661) thereafter. Increased first-year follow-up costs were associated with endomyocardial biopsies and length of readmissions. Cost per quality-adjusted life-year gained varied from $29,161 to $44,481 on sensitivity analysis. Freedom from treated rejections was 65.5% at 1 year, 63.2% at 3 years, and 59.5% at 5 years. Endomyocardial biopsies contributed to 52% of first-year follow-up costs.

CONCLUSIONS

Primary pediatric heart transplantation in Australia is cost-effective for long-term survivors, even for those supported by ventricular assist device. Surveillance endomyocardial biopsy was a major contributor to post-transplantation costs. Selective targeting of surveillance biopsies may be cost-saving.

Utility of screening echocardiogram after endomyocardial biopsy for identification of cardiac perforation or tricuspid valve injury

Per protocol, our institution obtains echocardiograms immediately after each EMB to rule out procedural complication. We sought to determine the incidence of echocardiogram-detected cardiac perforation and TV injury and to evaluate the utility of routine screening echocardiogram after each EMB in the current era. At a single center, 99% (1917/1942) EMB performed in 162 patients were immediately followed by an echocardiogram per protocol. There were five newly diagnosed pericardial effusions, and only one required pericardiocentesis. In the three echocardiograms demonstrating new flail TV, only one patient underwent surgical repair 2 months later. This study demonstrates the very low incidence of significant hemopericardium and TV injury after EMB in pediatric heart transplant recipients and argues against the utility of post-EMB echocardiograms to screen solely for procedural complications.

Current Topics and Controversies in Pediatric Heart Transplantation: Proceedings of the Pediatric Heart Transplantation Summit 2017

In October 2017, a pediatric heart transplant summit was held in Seattle-the first of its kind internationally-which focused solely upon controversies in pediatric end-stage heart failure management and pediatric heart transplantation. We selected five of the most popular and contentious topics and asked the speakers to provide a position paper. Worldwide, the vast majority of programs perform only a handful of pediatric heart transplants a year. Because of this, these "orphan" areas of investigation provide an opportunity for us as a community to aggregate our collective knowledge, which may represent the only viable way that we might sort through these complex and controversial issues in the field. We hope this represents the first of many such conferences and that this initial selection of papers encourages us to begin this collaborative process.