The yield of surveillance endomyocardial biopsies as a screen for cellular rejection in pediatric heart transplant patients

Short-term clinical outcomes and predicted cost savings of dd-cfDNA-led surveillance after pediatric heart transplantation

BACKGROUND

Endomyocardial biopsy (EMB)-led surveillance is common after pediatric heart transplantation (HT), with some centers performing periodic surveillance EMBs indefinitely after HT. Donor derived cell-free DNA (dd-cfDNA)-led surveillance offers an alternative, but knowledge about its clinical and economic outcomes, both key drivers of potential utilization, are lacking.

METHODS

Using single-center recipient and center-level data, we describe clinical outcomes prior to and since transition from EMB-led surveillance to dd-cfDNA-led surveillance of pediatric and young adult HT recipients. These data were then used to inform Markov models to compare costs between EMB-led and dd-cfDNA-led surveillance strategies.

RESULTS

Over 34.5 months, dd-cfDNA-led surveillance decreased the number of EMBs by 81.8% (95% CI 76.3%-86.5%) among 120 HT recipients (median age 13.3 years). There were no differences in the incidences of graft loss or death among all recipients followed at our center prior to and following implementation of dd-cfDNA-led surveillance (graft loss: 2.9 vs. 1.5 per 100 patient-years; p = .17; mortality: 3.7 vs. 2.2 per 100 patient-years; p = .23). Over 20 years from HT, dd-cfDNA-led surveillance is projected to cost $8545 less than EMB-led surveillance. Model findings were robust in sensitivity and scenario analyses, with cost of EMB, cost of dd-cfDNA testing, and probability of elevated dd-cfDNA most influential on model findings.

CONCLUSIONS

dd-cfDNA-led surveillance shows promise as a less invasive and cost saving alternative to EMB-led surveillance among pediatric and young adult HT recipients.

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.

Early findings after integration of donor-derived cell-free DNA into clinical care following pediatric heart transplantation

BACKGROUND

Endomyocardial biopsy (EMB) is costly and discomforting yet remains a key component of surveillance after pediatric heart transplantation (HT). Donor-derived cell-free DNA (dd-cfDNA) has been histologically validated with high negative predictive value, offering an alternative to surveillance EMB (sEMB).

METHODS

We implemented an alternative surveillance protocol using commercially available dd-cfDNA assays in place of sEMB after pediatric HT. Recipients ≧7 months post-HT with reassuring clinical assessment were referred for dd-cfDNA. When not elevated above the manufacturers' threshold, sEMB was deferred. Subsequent clinical status and results of follow-up EMB were analyzed.

RESULTS

Over 17 months, 58 recipients [34% female, median age at HT 3.1 years (IQR 0.6-10.6)] had dd-cfDNA assessed per protocol. Median age was 14.8 years (8.4-18.3) and time from HT 6.0 years (2.2-11.2). Forty-seven (81%) had non-elevated dd-cfDNA and 11 (19%) were elevated. During a median of 8.7 months (4.2-15), all are alive without allograft loss/new dysfunction. Among those with non-elevated dd-cfDNA, 24 (51%) had subsequent sEMB at 12.1 months (6.9-12.9) with 23 showing no acute rejection (AR): grade 0R/pAMR0 (n = 16); 1R(1A)/pAMR0 (n = 7). One had AR (grade 2R(3A)/pAMR0) on follow-up sEMB after decreased immunosuppression following a diagnosis of PTLD. All 11 with elevated dd-cfDNA had reflex EMB at 19 days (12-32) with AR in 4: grade 1R(1B-2)/pAMR0 (n = 3); 1R(1B)/pAMR2 (n = 1).

CONCLUSIONS

dd-cfDNA assessment in place of selected, per-protocol EMB decreased surveillance EMB by 81% in our pediatric HT recipient cohort with no short-term adverse outcomes. Individual center approach to surveillance EMB will influence the utility of these findings.

Practice variation in the diagnosis of acute rejection among pediatric heart transplant centers: An analysis of the pediatric heart transplant society (PHTS) registry

BACKGROUND

Freedom from rejection in pediatric heart transplant recipients is highly variable across centers. This study aimed to assess the center variation in methods used to diagnose rejection in the first-year post-transplant and determine the impact of this variation on patient outcomes.

METHODS

The PHTS registry was queried for all rejection episodes in the first-year post-transplant (2010-2019). The primary method for rejection diagnosis was determined for each event as surveillance biopsy, echo diagnosis, or clinical. The percentage of first-year rejection events diagnosed by surveillance biopsy was used to approximate the surveillance strategy across centers. Methods of rejection diagnosis were described and patient outcomes were assessed based on surveillance biopsy utilization among centers.

RESULTS

A total of 3985 patients from 56 centers were included. Of this group, 873 (22%) developed rejection within the first-year post-transplant. Surveillance biopsy was the most common method of rejection diagnosis (71.7%), but practices were highly variable across centers. The majority (73.6%) of first rejection events occurred within 3-months of transplantation. Diagnosis modality in the first-year was not independently associated with freedom from rejection, freedom from rejection with hemodynamic compromise, or overall graft survival.

CONCLUSIONS

Rejection in the first-year after pediatric heart transplant occurs in 22% of patients and most commonly in the first 3 months post-transplant. Significant variation exists across centers in the methods used to diagnose rejection in pediatric heart transplant recipients, however, these variable strategies are not independently associated with freedom from rejection, rejection with hemodynamic compromise, or overall graft survival.

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.

Impact of routine surveillance biopsy intensity on the diagnosis of moderate to severe cellular rejection and survival after pediatric heart transplantation

Data are lacking on RSB intensity and outcomes after pediatric heart transplantation. PHTS centers received a survey on RSB practices from 2005 to present. PHTS data were obtained for 2010-2013 and integrated with center-matched survey responses for analysis. Survey response rate was 82.6% (38/46). Centers were classified as low-, moderate-, and high-intensity programs based on RSB frequency (0-more than 8 RSB/y). RSB intensity decreased with increasing time from HT. Age at HT impacted RSB intensity mostly in year 1, with little to no impact in later years. Most centers have not replaced RSB with non-invasive methods, but many added ECHO and biomarker monitoring. Higher RSB intensity was not associated with decreased 4-year mortality (P=.63) or earlier detection of moderate to severe (ISHLT grade 2R/3R) cellular rejection (RSBMSR) in the first year (P=.87). First-year RSBMSR incidence did not differ with intensity or age at HT. Significant variability exists in RSB intensity, but with no impact on timing and incidence of RSBMSR or 4-year mortality. Reduction in RSB frequency may be safe in certain patients after pediatric HT.

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

BACKGROUND

The effect of age at transplant on rejection detected by routine surveillance biopsy (RSB) in pediatric heart transplant (HT) recipients is unknown. We hypothesized there would be low diagnostic yield and decreased prevalence of rejection detected on RSB in infants (age <1 year) when compared with children (age 1 to 9 years) and adolescents (age 10 to 18 years).

METHODS

We utilized Pediatric Heart Transplant Study (PHTS) data from 2010 to 2013 to analyze moderate-to-severe (ISHLT Grade 2R/3R) cellular rejection (MSR) detected only on RSB (RSBMSR).

RESULTS

RSB detected 280 of 343 (81.6%) episodes of MSR. RSBMSR was detected in all age groups even >5 years after HT. Infant RSBMSR had a greater proportion (p = 0.0025) occurring >5 years after HT (39.2 vs 18.4 vs 10.8%) and a lower proportion (p = 0.0009) occurring in the first year after HT (25.5 vs 60.6 vs 51.7%) compared with children and adolescents, respectively. Freedom from RSBMSR was 87 ± 7% in infants, 76 ± 6% in children and 73 ± 7% in adolescents 4 years after HT. In 1-year survivors who had RSBMSR in the first year after HT, the risk of RSBMSR occurring in Years 2 to 4 was significantly (p < 0.0001) greater than patients without RSBMSR in the first year (hazard ratio 21.28, 95% confidence interval 10.87 to 41.66), regardless of recipient age.

CONCLUSIONS

RSBMSR exists in all age groups after pediatric HT with long-term follow-up. The prevalence in infant recipients is highest >5 years after HT. Those with RSBMSR in the first year after HT are at a high risk for recurrent rejection regardless of age at HT.

Variation in the use of surveillance endomyocardial biopsy among pediatric heart transplant centers over time

EMB is widely utilized for graft surveillance after HTx; however, there is significant variation in the frequency of surveillance EMB use during the first year post-HTx. The aim of this study was to assess changes in the utilization of surveillance EMB over time among member institutions of PHTS. A survey of PHTS centers assessing the frequency of surveillance EMB use during the first year post-HTx was conducted in 2006. The same survey was repeated in 2014 to assess changes in practice over time. The number of EMB in infants ranged from 0 to 9 and in adolescents 0 to 16. The number of EMB decreased or remained unchanged in the majority of centers. Fewer EMB are performed in infants compared to adolescents and this practice did not change over time. There was a significant decrease in surveillance EMB use in adolescents (p = 0.012). International centers perform significantly fewer EMB in adolescents when compared to centers within the United States (p = 0.006). There continues to be significant variation in the utilization of surveillance EMB, with a shift toward less reliance on EMB for adolescents in the current era. Further research is necessary to determine the optimal frequency of invasive monitoring that reduces costs without compromising outcomes.

Organizational structure and processes in pediatric heart transplantation: a survey of practices

Despite emerging literature on pediatric heart transplantation, there continues to be variation in current practices. The degree of variability among heart transplant programs has not been previously characterized. The purpose of this study was to evaluate organizational structure and practices of pediatric heart transplant programs. The UNOS database was queried to identify institutions according to volume. Coordinators from 50 institutions were invited to participate with a 70% response rate. Centers were grouped by volume into four categories. Some institutional practices were dominated by clear volume trends. Ninety-five percent of larger centers routinely transplant patients with known antibody sensitization and report a broader range and acuity of recipients. Ninety-four percent report problems with non-adherence. Sixty-nine percent of centers routinely require prospective crossmatches. There was dramatic variation in the use of steroids across all centers. Sixty-five percent of centers transition adolescents to an adult program. Prophylaxis protocols were also highly inconsistent. This survey provided a comprehensive insight into current practices at pediatric heart transplant programs. The results delineated remarkably variable strategies for routine aspects of care. Analysis of divergence along with uniformity across protocols is a valuable exercise and may serve as a stepping-stone toward ongoing cooperation and clarity for evidence-based practice protocols.

Endomyocardial biopsy and selective coronary angiography are low-risk procedures in pediatric heart transplant recipients: results of a multicenter experience

BACKGROUND

No prior reports documenting the safety and diagnostic yield of cardiac catheterization and endomyocardial biopsy (EMB) in heart transplant recipients include multicenter data.

METHODS

Data on the safety and diagnostic yield of EMB procedures performed in heart transplant recipients were recorded in the Congenital Cardiac Catheterization Outcomes Project database at 8 pediatric centers during a 3-year period. Adverse events (AEs) were classified according to a 5-level severity scale. Generalized estimating equation models identified risk factors for high-severity AEs (HSAEs; Levels 3-5) and non-diagnostic biopsy samples.

RESULTS

A total of 2,665 EMB cases were performed in 744 pediatric heart transplant recipients (median age, 12 years [interquartile range, 4.8, 16.7]; 54% male). AEs occurred in 88 cases (3.3%), of which 28 (1.1%) were HSAEs. AEs attributable to EMB included tricuspid valve injury, transient complete heart block, and right bundle branch block. Amongst 822 cases involving coronary angiography, 10 (1.2%) resulted in a coronary-related AE. There were no myocardial perforations or deaths. Multivariable risk factors for HSAEs included fewer prior catheterizations (p = 0.006) and longer case length (p < 0.001). EMB yielded sufficient tissue for diagnosis in 99% of cases. Longer time since heart transplant was the most significant predictor of a non-diagnostic biopsy sample (p < 0.001).

CONCLUSIONS

In the current era, cardiac catheterizations involving EMB can be performed in pediatric heart transplant recipients with a low AE rate and high diagnostic yield. Risk of HSAEs is increased in early post-transplant biopsies and with longer case length. Longer time since heart transplant is associated with non-diagnostic EMB samples.

Decline in rejection in the first year after pediatric cardiac transplantation: a multi-institutional study

BACKGROUND

Rejection is a major cause of morbidity and mortality after pediatric heart transplantation (HTx). Survival after pediatric HTx has improved over time, but whether there has been an era-related improvement in the occurrence of allograft rejection is unknown.

METHODS

The Pediatric Heart Transplant Study (PHTS) database was queried for patients who underwent HTx from January 1993 to December 2005 to determine the incidence of rejection and identify factors associated with the first episode of rejection in the first year after HTx.

RESULTS

Data were reviewed in 1,852 patients from 36 centers. The incidence of rejection declined over 13 years at a rate of -2.58 +/- 0.41 (p < 0.001) from approximately 60% to 40% (p < 0.001). The mean number of episodes of rejection also significantly fell at a rate of -0.05 +/- 0.01 per patient/year from 1.19 to 0.66 (p < 0.001). The incidence of rejection with hemodynamic compromise and death from rejection did not change. Multivariate analysis for the risk of a first rejection episode demonstrated decreased risk of rejection with later year of HTx (odds ratio [OR], 0.88; 95% confidence interval [CI], 0.85-0.91; p < 0.001) and use of mechanical support (OR, 0.65; 95% CI, 0.42-0.99; p = 0.046). Increased risk of rejection was associated with positive donor-specific crossmatch (OR, 1.85; 95% CI, 1.18-2.88; p = 0.007) and older recipient age (OR, 1.05; 95% CI, 1.02-1.07; p < 0.001).

CONCLUSIONS

Although the overall incidence and prevalence of rejection has substantially decreased over time in pediatric HTx recipients in the first year after HTx, the rate of rejection with hemodynamic compromise or death from rejection remains unchanged.

Screening for rejection in symptomatic pediatric heart transplant recipients: the sensitivity of BNP

As the pediatric OHT population expands, there is increasing demand for convenient, yet sensitive screening techniques to identify children with acute rejection when they present to acute care facilities. In children, symptoms of acute rejection or other causes of graft dysfunction are often non-specific and can mimic other childhood illnesses. The aim of this study was to assess the utility of BNP as a biomarker to assist providers in clinical decision-making when evaluating symptomatic pediatric heart transplant patients. One hundred twenty-two urgent care and emergency room visits from 53 symptomatic pediatric OHT patients were retrospectively reviewed to evaluate the relationship between BNP levels, symptoms, and clinical diagnosis at these visits. An ROC curve was generated to determine the accuracy of BNP as a screening tool for acute rejection in this patient population. In this group of patients, a BNP value of >700 pg/mL was 100% sensitive and 92% specific for detecting allograft acute rejection (NPV of 100%). We concluded that BNP is a highly sensitive screening test for acute rejection in symptomatic pediatric heart transplant patients.

The use of Doppler tissue imaging to predict cellular and antibody-mediated rejection in pediatric heart transplant recipients

DTI indices have been associated with cellular rejection in adult heart transplant recipients, but their predictive value in pediatric recipients is unknown. The purpose of this study was to evaluate DTI measures in the detection of cellular and AMR in pediatric heart transplant recipients. One hundred and forty-eight pediatric heart transplant recipients who had 267 cardiac catheterization procedures with EMB, echocardiogram with DTI, and BNP level performed on the same day were included in the study. For the mitral and tricuspid valves, the ratios (E/E') between the early diastolic inflow velocity by pulsed Doppler (E, m/s) and the early diastolic annular velocity by DTI (E', m/s) were obtained and compared between subjects with and without rejection. Of the 148 recipients, 30 subjects had a total of 37 episodes of rejection: 10 cellular (>or=1B), 17 AMR, and 10 biopsy-negative clinical rejection. Mitral and tricuspid valve E/E' ratios were significantly higher in rejectors than in non-rejectors (5.5 +/- 1.3 vs. 4.4 +/- 1.4, p < 0.001 and 4.9 +/- 2.1 vs. 4.1 +/- 1.5, p < 0.01, respectively). By multivariate linear regression, mitral valve E/E' was an independent predictor of rejection. Mitral and tricuspid valve E/E' <5.0 had 93% and 89% NPV, respectively, for rejection. Mitral and tricuspid valve E/E' ratios <5.0 may be useful non-invasive screening measures to exclude rejection in pediatric heart transplant recipients.

Unsuspected rejection episodes on routine surveillance endomyocardial biopsy post-heart transplant in paediatric patients

The use of routine endomyocardial biopsies post-heart transplant in children remains controversial. It is generally accepted as the gold standard for detecting rejection, but details of the surveillance protocol, such as number and timing of biopsies, remain uncertain, with suggestions that recent advances in immunosuppressant therapy have obviated the need to perform surveillance biopsies. We retrospectively analysed results of endomyocardial biopsies performed in our unit since the introduction of a policy of three routine biopsies in the first six months post-transplantation. We specifically examined only routine surveillance biopsies in order to determine whether clinically unsuspected cases of rejection were identified. Between January 2002 and April 2006, 63 children completed three biopsies in the first six months post-transplant. Of 189 surveillance endomyocardial biopsies, 19 (10%) patients showed significant, grade III or above, rejection. One patient had two episodes of rejection. In only one case the child was haemodynamically unstable, four cases were mildly unwell, and 14 of 19 (74%) cases demonstrated no cardiac symptoms. Four of eight cases treated with sirolimus for some part of their post-transplant course had an episode of rejection and of 54 tacrolimus-treated patients, 13 had an episode of asymptomatic rejection detected. One of the seven infants had significant episode of rejection. Asymptomatic, clinically significant rejection is detected in about 10% of biopsies overall using a three-biopsy protocol in the first six months after paediatric heart transplantation, and occurs in 24% of tacrolimus-treated patients. More frequent surveillance appears needed in children treated with sirolimus, but less frequent surveillance may be possible in infants.

Humoral Rejection in Pediatric Orthotopic Heart Transplantation

BACKGROUND

Pediatric heart transplant grafts may fail without evidence of cellular rejection or transplant coronary artery disease. The role of antibody-mediated humoral rejection (HR) in graft failure has not yet been described in the pediatric population.

METHODS

We reviewed the medical records of 103 pediatric heart transplantations performed at our institution from July 1997 to June 2004. Biopsy specimens were evaluated for HR histologically and by immunoperoxidase and immunofluorescence staining. Risk factors for HR were determined by statistical analysis. Graft survival curves were constructed and compared for patients testing negative or positive for HR.

RESULTS

A total of 358 endomyocardial biopsies (EMBs) from 103 pediatric heart transplant patients (age 3 weeks to 20 years; 52% males) were analyzed for HR. Thirty-six grafts (32%) showed evidence of HR. Grafts with a history of HR during the first year after transplant had a 47% failure rate over 3 years, compared with 29% of those hearts with no evidence of HR (p = 0.06). Although patients with congenital heart disease (CHD) appeared to be at greatest risk for developing HR (p = 0.01), patients with positive donor-specific crossmatch data showed a trend toward more significant risks for HR (p = 0.055). Hemodynamic data (including pulmonary capillary wedge pressure [PCWP] and cardiac index [CI]), left ventricular ejection fraction (LVEF), gender matching, recipient age, race of recipient vs donor and pre-transplant panel-reactive antibody (PRA) were not predictive of HR.

CONCLUSIONS

Patients with a pathologic diagnosis of HR have increased graft failure rates and overall mortality. Patients with congenital heart disease and positive cross-match results may be at increased risk for HR.

Should we be doing routine biopsy after heart transplantation in a new era of anti-rejection?

PURPOSE OF REVIEW

The endomyocardial biopsy has defined the diagnosis of rejection in cardiac transplantation and has historically been a vital tool when rejection rates following transplantation were high. Surveillance biopsies have been the cornerstone of post-transplant management, as signs or symptoms of rejection are non-specific. With significant improvements in immunosuppressive therapy, however, the incidence of clinically significant rejection has declined, bringing into question the need for routine surveillance biopsy. This article reviews the current role of the endomyocardial biopsy in the management of patients following cardiac transplantation.

RECENT FINDINGS

The endomyocardial biopsy is also limited by sub-optimal interobserver reproducibility, a lack of consensus with regard to treating certain grades of rejection, and often a lack of histological findings in patients with hemodynamic compromise, which frequently responds to anti-rejection therapy. Recent refinements, however, have allowed improved diagnosis of antibody mediated rejection, a relatively recently recognized entity. Moreover, a number of non-invasive modalities have been investigated recently as potential substitutes for the endomyocardial biopsy in detecting rejection.

SUMMARY

Despite the development of a variety of non-invasive methods for the detection of rejection, the endomyocardial biopsy will remain important in the management of patients following cardiac transplantation, as non-invasive techniques are associated with low specificity for the diagnosis of rejection. A new standardized classification will likely improve the utility of the biopsy by simplifying interpretation of cellular rejection and importantly allowing recognition of antibody-mediated rejection.

Cost-effectiveness of Pediatric Heart Transplantation

BACKGROUND

Survival after pediatric heart transplantation has continued to improve. Nonetheless, graft survival is generally <15 years and the costs of transplantation and subsequent immunosuppression are substantial. In the present study, we sought to examine the cost-effectiveness of pediatric heart transplantation.

METHODS

Data from 95 pediatric subjects undergoing transplantation at our institution from 1997 through 2004 were reviewed to determine the costs of pediatric heart transplantation. Costs included pre-transplant care, organ procurement, initial hospitalization and follow-up care. Life expectancy was derived from the United Network of Organ Sharing data set. Data were reported as cost per quality-adjusted life-years (QALYs) gained, which were discounted at 3%. Cost-effectiveness was stratified by primary transplantation vs re-transplantation.

RESULTS

The mean cost of initial hospitalization and organ procurement was $221,897 per patient for primary transplant and $285,296 per patient for re-transplant. Annual follow-up costs were estimated to be $18,141 in the first year (excluding the first 90 days post-transplant) and $18,480 per year thereafter. Under base-case assumptions, costs per QALY gained were $49,679 for primary transplantation and $87,883 for re-transplantation. Sensitivity analysis yielded a cost-utility range of $44,943 to $57,628 per QALY gained for primary transplantation and $70,834 to $103,661 per QALY gained for re-transplantation.

CONCLUSIONS

Costs of primary pediatric heart transplantation are within the accepted range of cost effectiveness. Pediatric heart re-transplantation has higher costs relative to benefits gained owing to shorter graft survival.

Does duration of donor brain injury affect outcome after orthotopic pediatric heart transplantation?

OBJECTIVE

We tested the hypothesis that duration of donor brain injury and death would have an adverse effect on recipient rejection and mortality in pediatric heart transplantation.

METHODS

Ninety-three cardiac transplants were performed at our center from July 1, 1997, through June 30, 2003. The primary study end points were the number of rejection episodes and the time to first rejection. Secondary outcomes were early and late mortality.

RESULTS

Among 88 recipients of 93 cardiac allografts, 5 (6%) and 1 (1%) received second and third allografts, respectively. Overall patient mortality (3 early and 2 late) was 6% (5/88), and overall graft loss was 6% (6/93). Median time from donor brain injury to declaration of brain death (brain injury interval), time from brain death to donor cardiectomy (brain death interval), and graft ischemia time were 38, 24, and 3.3 hours, respectively. Cox regression analysis (adjusting for United Network for Organ Sharing status, ventilator dependence, extracorporeal membrane oxygenation and ventricular-assist device status, diagnosis of congenital heart disease, sex and cytomegalovirus mismatches, and type of immunosuppression) demonstrated that recipients of donor hearts with relatively long periods from brain injury to death declaration or from death to organ removal had significantly improved rejection-free survival (hazard ratios 0.3, P = .01, and 0.5, P = .05, for brain injury and brain death times, respectively). Prolonged donor heart ischemia did not impact rejection rate. Increasing brain injury interval, brain death interval, and graft ischemia time had no significant effect on mortality.

CONCLUSION

Longer brain injury and death intervals correlated with improved freedom from rejection but had no effect on mortality.

Is biopsy-proven cellular rejection an important clinical consideration in heart transplantation?

PURPOSE OF REVIEW

Immunosuppression strategies to prevent allograft rejection represent the cornerstone of long-term survival after heart transplantation. Endomyocardial biopsy has defined rejection in clinical cardiac transplantation and established a threshold for therapy. With the development of more effective immunosuppression modalities and the asymptomatic nature of most histologic rejection episodes, controversy exists regarding the need to augment immunosuppression based purely on histologic findings.

RECENT FINDINGS

The frequency of histologic rejection has declined with current immunosuppression. Resolution of lower grades of histologic rejection without treatment is the norm in both pediatric and adult heart transplant studies. Recurrent rejection episodes have been linked to the subsequent development of allograft coronary artery disease, and late rejection (even if asymptomatic) is associated with decreased survival in pediatric heart transplant recipients. Black race is a risk factor for recurrent rejection and reduced survival after late cellular rejection. Apoptosis of inflammatory cells is more evident during and after histologic rejection treated with corticosteroids. Despite numerous noninvasive modalities evaluated for the detection of rejection, to date noninvasive methods cannot reliably predict histologic rejection.

SUMMARY

Histologic rejection appears less common with current immunosuppressive strategies, and controversy exists about the need to treat asymptomatic rejection. It remains unproven whether non-treatment of moderate or greater rejection (>/=3A) increases the likelihood of recurrent rejection, which if present, may increase the risk of allograft coronary disease and/or reduced long-term survival.

Progress in heart transplantation

The field of heart transplantation was built upon the discoveries of immunity and tolerance by Landsteiner, Medawar, Burnet, and others, as well as technical advancements in surgical technique by Carrel. Since the first successful human heart transplant performed by Christiaan Barnard in 1967, there has been substantial progress in the field of heart transplantation, especially over the last several decades. With advances in immunosuppression and surgical techniques, the rates of acute rejection and infection leading to graft failure have declined. However, the detection of acute and chronic allograft rejection remains one of the most important yet unsettled matters. As such, many new horizons exist for further advancement of the field of heart transplantation and for improving the outcomes of the patients we serve.