Pediatric heart transplantation: 23-year single-center experience

Pulmonary hemodynamics before and after pediatric heart transplantation

BACKGROUND

Pulmonary hypertension (PH) may limit the outcome of pediatric heart transplantation (pHTx). We evaluated pulmonary hemodynamics in children undergoing pHTx.

METHODS

Cross-sectional, single-center, observational study analyzing pulmonary hemodynamics in children undergoing pHTx.

RESULTS

Twenty-three children (female 15) underwent pHTx at median (IQR) age of 3.9 (.9-8.2) years with a time interval between first clinical signs and pHTx of 1.1 (.4-3.2) years. Indications for pHTx included cardiomyopathy (CMP) (n = 17, 74%), congenital heart disease (CHD) (n = 5, 22%), and intracardiac tumor (n = 1, 4%). Before pHTx, pulmonary hemodynamics included elevated pulmonary artery pressure (PAP) 26 (18.5-30) mmHg, pulmonary capillary wedge pressure (PCWP) 19 (14-21) mmHg, left ventricular enddiastolic pressure (LVEDP) 17 (13-22) mmHg. Transpulmonary pressure gradient (TPG) was 6.5 (3.5-10) mmHg and pulmonary vascular resistance (Rp) 2.65 WU*m2 (1.87-3.19). After pHTx, at immediate evaluation 2 weeks after pHTx PAP decreased to 20.5 (17-24) mmHg, PCWP 14.5 (10.5-18) mmHg (p < .05), LVEDP 16 (12.5-18) mmHg, TPG 6.5 (4-12) mmHg, Rp 1.49 (1.08-2.74) WU*m2 resp.at last invasive follow up 4.0 (1.4-6) years after pHTx, to PAP 19.5 (17-21) mmHg (p < .05), PCWP 13 (10.5-14.5) mmHg (p < .05), LVEDP 13 (10.5-14) mmHg, TPG 7 (5-9.5) mmHg, Rp 1.58 (1.38-2.19) WU*m2 (p < .05). In CHD patients PAP increased (p < .05) after pHTx at immediate evaluation and decreased until last follow-up (p < .05), while in CMP patients there was a continuous decline of mean PAP values immediately after HTx (p < .05).

CONCLUSIONS

While PH before pHTx is frequent, after pHTx the normalization of PH starts immediately in CMP patients but is delayed in CHD patients.

Single-drug immunosuppression is associated with noninferior medium-term survival in pediatric heart transplant recipients

BACKGROUND

Patients are usually maintained on at least 2 immunosuppressive drugs (ISDs) after the first year post heart transplant. Anecdotally, some children are switched to single-drug monotherapy (a single ISD) for various reasons and varying durations. Outcomes associated with differences in immunosuppression after heart transplantation are unknown for children.

OBJECTIVES

A priori we defined a noninferiority hypothesis for monotherapy compared to ≥2 ISDs. The primary outcome was graft failure, a composite of death and retransplantation. Secondary outcomes included rejection, infection, malignancy, cardiac allograft vasculopathy and dialysis.

METHODS

This international, multicenter, retrospective, observational cohort study used data from the Pediatric Heart Transplant Society. We included patients who underwent first-time heart transplant <18 years of age between 1999 and 2020 with ≥1 year of follow-up data available.

RESULTS

Our analysis included 3493 patients with a median time post-transplant of 6.7 years. There were 893 patients (25.6%) switched to monotherapy at least once with the remaining 2600 patients always on ≥2 ISDs. The median time on monotherapy after the first year post-transplant was 2.8 years (range 1.1-5.9 years). We found an adjusted hazard ratio (HR) of 0.65 (95%CI: 0.47-0.88) favoring monotherapy compared to ≥2 ISDs (p = 0.002). There were no meaningful differences in the incidence of secondary outcomes between groups, except for a lower rate of cardiac allograft vasculopathy in patients on monotherapy (HR 0.58, 95%CI: 0.45-0.74).

CONCLUSIONS

For pediatric heart transplant recipients placed on monotherapy, immunosuppression with a single ISD after the first year post-transplant was noninferior to standard therapy with ≥2 ISDs in the medium term.

CONDENSED ABSTRACT

Some children are switched to a single immunosuppressive drug (ISD) for various reasons after heart transplant, but outcomes associated with differences in immunosuppression are unknown for children. We assessed graft failure in children on a single ISD (monotherapy) compared to ≥2 ISDs in a cohort of 3493 children with a first heart transplant. We found an adjusted hazard ratio of 0.65 (95%CI: 0.47-0.88) favoring monotherapy. We concluded that for pediatric heart transplant recipients placed on monotherapy, immunosuppression with a single ISD after the first year post-transplant was non-inferior to standard therapy with ≥2 ISDs in the medium term.

The Dutch national paediatric heart transplantation programme: outcomes during a 23-year period

BACKGROUND

Since 1998, there has been a national programme for paediatric heart transplantations (HT) in the Netherlands. In this study, we investigated waiting list mortality, survival post-HT, the incidence of common complications, and the patients' functional status during follow-up.

METHODS

All children listed for HT from 1998 until October 2020 were included. Follow-up lasted until 1 January 2021. Data were collected from the patient charts. Survival, post-operative complications as well as the functional status (Karnofsky/Lansky scale) at the end of follow-up were measured.

RESULTS

In total, 87 patients were listed for HT, of whom 19 (22%) died while on the waiting list. Four patients were removed from the waiting list and 64 (74%) underwent transplantation. Median recipient age at HT was 12.0 (IQR 7.2-14.4) years old; 55% were female. One-, 5‑, and 10-year survival post-HT was 97%, 95%, and 88%, respectively. Common transplant-related complications were rejections (50%), Epstein-Barr virus infections (31%), cytomegalovirus infections (25%), post-transplant lymphoproliferative disease (13%), and cardiac allograft vasculopathy (13%). The median functional score (Karnofsky/Lansky scale) was 100 (IQR 90-100).

CONCLUSION

Children who undergo HT have an excellent survival rate up to 10 years post-HT. Even though complications post-HT are common, the functional status of most patients is excellent. Waiting list mortality is high, demonstrating that donor availability for this vulnerable patient group remains a major limitation for further improvement of outcome.

Long-term experience using CNI-free immunosuppression in selected paediatric heart transplant recipients

BACKGROUND

CNI-free immunosuppression with conversion to mTORi-based immunosuppression has been demonstrated to reduce CNI-toxicity and to exhibit anti-proliferative properties. However, the experience of CNI-free immunosuppression in paediatric heart transplantation is limited.

METHODS

A retrospective analysis was conducted of 129 paediatric heart transplants performed between 1997 and 2015. Fifteen patients with clinically indicated conversion from CNI-based to CNI-free immunosuppression were identified. Survival data, rejection episodes, renal function, post-transplantation lymphoproliferative disorder and CAV, including examination with OCT were analysed.

RESULTS

Immunosuppression conversion was successful in all patients. Fourteen of 15 patients (93%) are currently living with good graft function. Median post-transplant survival was 15 years (range, 5-23 years), and median follow-up since conversion was 6 years (range, 1-11 years). Mild (grade 1R) ACR was present in three patients after discontinuation of CNIs. The recovery of renal function with a significant increase in eGFR was observed at 1 and 3 years after conversion. No patient had angiographic signs of macroscopic CAV according to the current ISHLT classification; however, OCT showed the signs of angiographically silent CAV in all patients. CAV did not progress in any patient, implying CAV was stabilised by mTORi-based CNI-free immunosuppression.

CONCLUSIONS

CNI-free immunosuppression based on mTORis is a safe and appropriate strategy for maintenance therapy in selected paediatric patients, significantly improves renal function and stabilises CAV. OCT revealed early development of angiographically silent CAV.

Aetiology and 30-Year Long-Term Outcome of Children with Cardiomyopathy Necessitating Heart Transplantation

Studies assessing the long-term outcome after heart transplantation HTX in patients with cardiomyopathy (CM) in the paediatric age range are rare. The aim of this study was to determine the survival rate of children with CM undergoing HTX and to analyse how aetiology of cardiomyopathy influenced morbidity and mortality. We retrospectively analysed the medical records of children; who were transplanted in our centre between June 1988 and October 2019. 236 heart transplantations were performed since 1988 (9 re-transplants). 98 of 227 patients (43.2%) were transplanted because of CM. Survival rates were 93% after 1; 84% after 10 and 75% after 30 years. Overall; the aetiology of CM could be clearly identified in 37 subjects (37.7%). This rate increased up to 66.6% (12/19) by applying a comprehensive diagnostic workup since 2016. The survival rate was lower (p < 0.05) and neurocognitive deficits were more frequent (p = 0.001) in subjects with systemic diseases than in individuals with cardiac-specific conditions. These data indicate that the long-term survival rate of children with CM after HTX in experienced centers is high. A comprehensive diagnostic workup allows unraveling the basic defect in the majority of patients with CM undergoing HTX. Aetiology of CM affects morbidity and mortality in subjects necessitating HTX.

Myocardial velocity, intra-, and interventricular dyssynchrony evaluated by tissue phase mapping in pediatric heart transplant recipients

BACKGROUND

Endomyocardial biopsy (EMB) is the standard method for detecting allograft rejection in pediatric heart transplants (Htx). As EMB is invasive and carries a risk of complications, there is a need for a noninvasive alternative for allograft monitoring.

PURPOSE

To quantify left and right ventricular (LV & RV) peak velocities, velocity twist, and intra-/interventricular dyssynchrony using tissue phase mapping (TPM) in pediatric Htx compared with controls, and to explore the relationship between global cardiac function parameters and the number of rejection episodes to these velocities and intra-/interventricular dyssynchrony.

STUDY TYPE

Prospective.

SUBJECTS

Twenty Htx patients (age: 16.0 ± 3.1 years, 11 males) and 18 age- and sex-matched controls (age: 15.5 ± 4.3 years, nine males).

FIELD STRENGTH/SEQUENCE

5T; 2D balanced cine steady-state free-precession (bSSFP), TPM (2D cine phase contrast with three-directional velocity encoding).

ASSESSMENT

LV and RV circumferential, radial, and long-axis velocity-time curves, global and segmental peak velocities were measured using TPM. Short-axis bSSFP images were used to measure global LV and RV function parameters.

STATISTICAL TESTS

A normality test (Lilliefors test) was performed on all data. For comparisons, a t-test was used for normally distributed data or a Wilcoxon rank-sum test otherwise. Correlations were determined by a Pearson correlation.

RESULTS

Htx patients had significantly reduced LV (P < 0.05-0.001) and RV (P < 0.05-0.001) systolic and diastolic global and segmental long-axis velocities, reduced RV diastolic peak twist (P < 0.01), and presented with higher interventricular dyssynchrony for long-axis and circumferential motions (P < 0.05-0.001). LV diastolic long-axis dyssynchrony (r = 0.48, P = 0.03) and RV diastolic peak twist (r = -0.64, P = 0.004) significantly correlated with the total number of rejection episodes.

DATA CONCLUSION

TPM detected differences in biventricular myocardial velocities in pediatric Htx patients compared with controls and indicated a relationship between Htx myocardial velocities and rejection history.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2020;51:1212-1222.

Patterns of kidney injury in pediatric nonkidney solid organ transplant recipients

The incidence of acute kidney injury (AKI) and its impact on chronic kidney disease (CKD) following pediatric nonkidney solid organ transplantation is unknown. We aimed to determine the incidence of AKI and CKD and examine their relationship among children who received a heart, lung, liver, or multiorgan transplant at the Hospital for Sick Children between 2002 and 2011. AKI was assessed in the first year posttransplant. Among 303 children, perioperative AKI (within the first week) occurred in 67% of children, and AKI after the first week occurred in 36%, with the highest incidence among lung and multiorgan recipients. Twenty-three children (8%) developed CKD after a median follow-up of 3.4 years. Less than 5 children developed end-stage renal disease, all within 65 days posttransplant. Those with 1 AKI episode by 3 months posttransplant had significantly greater risk for developing CKD after adjusting for age, sex, and estimated glomerular filtration rate at transplant (hazard ratio: 2.77, 95% confidence interval, 1.13-6.80, P trend = .008). AKI is common in the first year posttransplant and associated with significantly greater risk of developing CKD. Close monitoring for kidney disease may allow for earlier implementation of kidney-sparing strategies to decrease risk for progression to CKD.

Hearts transplanted after circulatory death in children: Analysis of the International Society for Heart and Lung Transplantation registry

We aimed to describe worldwide DCD HT experience in children using the International Society for Heart and Lung Transplantation Registry. The Registry was queried for primary HT performed in children (2005-2014). Kaplan-Meier analysis was used to assess survival for recipients grouped by DCD or DBD hearts. Recipient characteristics were compared between DCD and DBD and between survivors and non-survivors of DCD HT. Among 3877 pediatric HT performed, 21 (0.5%) were DCD. DCD 1-year survival was 61% vs 91% DBD, P < .01. DCD recipients were more often supported by ECMO pre-HT (24% vs 6%, P < .001) and more often receiving inhaled nitric oxide (10% vs 0.6%, P < .001) compared to DBD. Older DCD recipients had significantly lower 1-year survival of 57% vs 93% for DBD, P < .01. Survival for infant DCD recipients was not statistically different to DBD recipients (survival 62% at 1 year and 62% at 5 years for DCD vs 85% at 1 year and 77% at 5 years for DBD, P = .15). Recipients of DCD HT who died were more often supported by ECMO pre-HT (56% non-survivors vs 0% survivors, P = .004) and receiving mechanical ventilation (44% vs 0%, P = .012). DCD HT is uncommon in children. DCD-independent factors in recipients may have contributed to worse survival as DCD recipients who died were more often supported by ECMO and mechanical ventilation. More research is needed to identify donor factors and recipient factors that contribute to mortality after DCD HT.

Rehospitalization after pediatric heart transplantation: Incidence, indications, and outcomes

We report the patterns of rehospitalization after pediatric heart transplant (Htx) at a single center. Retrospective review of 107 consecutive pediatric Htx recipients between January 22, 2007, and August 28, 2014, who survived their initial transplant hospitalization. The frequency, duration, and indications for all hospitalizations between transplant hospitalization discharge and September 30, 2015, were analyzed. A total of 444 hospitalization episodes occurred in 90 of 107 (84%) patients. The median time to first rehospitalization was 59.5 (range 1-1526) days, and the median length of stay was 2.5 (range 0-81) days. There were an average of two hospitalizations per patient in the first year following transplant hospitalization, declining to about 0.8 per patient per year starting at 3 years post-transplant. Admissions for viral infections were most common, occurring in 93 of 386 (24%), followed by rule out sepsis in 61 of 386 (16%). Admissions for suspected or confirmed rejection were less frequent, accounting for 41 of 386 (11%) and 31 of 386 (8%) of all admissions, respectively. Survival to discharge after rehospitalization was 97%. Hospitalization is common after pediatric Htx, particularly in the first post-transplant year, with the most frequent indications for hospitalization being viral illness and rule out sepsis. After the first post-transplant year, the risk for readmission falls significantly but remains constant for several years.

Diffuse Myocardial Fibrosis in Children After Heart Transplantations: A Magnetic Resonance T1 Mapping Study

BACKGROUND

It is unclear whether the myocardium undergoes accelerated fibrotic remodeling in children after heart transplantation (HTx).

METHODS

In this prospective study, cardiac magnetic resonance (CMR) studies in 17 patients 1.3 years (median, range 0.03-12.6 years) after HTx (mean age, 9.8 ± 6.2 years; 8 girls) were compared to CMR studies in 9 healthy controls (mean age, 12.4 ± 2.4 years; 4 girls). T1 measurements were performed at a midventricular short axis slice before (ie, native T1 times) and after the application of 0.2 mmol/kg gadopentetate dimeglumine in the interventricular septum, left ventricular (LV) free wall and encompassing the entire LV myocardium. The tissue-blood partition coefficient (TBPC), reflecting the degree of diffuse myocardial fibrosis, was calculated as a function of the ratio of T1 change of myocardium compared to blood. Native T1 times and TBPC were correlated with echocardiographic parameters of diastolic function.

RESULTS

Native T1 times were significantly higher in HTx patients compared to controls in all regions assessed (LV free wall 973 ± 42 vs 923 ± 12 ms; P < 0.005; interventricular septum 1003 ± 31 vs 974 ± 21 ms, P < 0.05; entire LV myocardium 987 ± 33 vs 951 ± 16 ms; P < 0.005) and correlated with LV E/e' as an echocardiographic marker of diastolic dysfunction (r = 0.54, P < 0.05). The TBPC was elevated in the LV free wall (0.45 ± 0.06 vs 0.40 ± 0.03, P < 0.005) and the entire LV myocardium (0.47 ± 0.06 vs 0.43 ± 0.03, P < 0.05).

CONCLUSIONS

Evidence of diffuse myocardial fibrosis and is already present in children after HTx. It appears to be associated with diastolic dysfunction.

Influence of Posttransplant Lymphoproliferative Disorder on Survival in Children After Heart Transplantation

The influence of posttransplant lymphoproliferative disorder (PTLD) on long-term survival in children after heart transplantation (HTx) is not well studied. The United Network for Organ Sharing database was queried from 1987 to 2013 for data on PTLD in relation to induction immunosuppression and recipient Epstein-Barr virus status in children (<18 years of age) who underwent HTx. Of 6818 first-time pediatric heart transplants, 5169 had follow-up data on posttransplant malignancy, with 360 being diagnosed with PTLD. Univariate Cox analysis identified diminished survival after PTLD onset using a time-varying measure of PTLD (HR 2.208; 95 % CI 1.812, 2.689; p < 0.001), although Kaplan-Meier survival functions found no difference in survival between the group ever diagnosed with PTLD and the non-PTLD reference group (log-rank test: χ 1 (2)  = 0.02; p = 0.928). A multivariate Cox model found a greater mortality hazard associated with the development of PTLD after adjusting for recipient EBV seronegativity and other covariates (HR 3.024; 95 % CI 1.902, 4.808; p < 0.001). Induction immunosuppression at time of HTx did not significantly influence posttransplant mortality. The development of PTLD adversely influenced long-term survival in children after HTx after adjusting for confounding variables.

Heart transplantation in congenital heart disease: in whom to consider and when?

Due to impressive improvements in surgical repair options, even patients with complex congenital heart disease (CHD) may survive into adulthood and have a high risk of end-stage heart failure. Thus, the number of patients with CHD needing heart transplantation (HTx) has been increasing in the last decades. This paper summarizes the changing etiology of causes of death in heart failure in CHD. The main reasons, contraindications, and risks of heart transplantation in CHD are discussed and underlined with three case vignettes. Compared to HTx in acquired heart disease, HTx in CHD has an increased risk of perioperative death and rejection. However, outcome of HTx for complex CHD has improved over the past 20 years. Additionally, mechanical support options might decrease the waiting list mortality in the future. The number of patients needing heart-lung transplantation (especially for Eisenmenger's syndrome) has decreased in the last years. Lung transplantation with intracardiac repair of a cardiac defect is another possibility especially for patients with interatrial shunts. Overall, HTx will remain an important treatment option for CHD in the near future.

State of the art in paediatric heart transplantation: the Berlin experience

Enormous progress has been made in paediatric heart transplantation since the first unsuccessful effort by Kantrowitz in 1967. Early reports of children undergoing heart transplantation showed alarmingly high perioperative mortality rates of 25-60%, with the diagnosis of congenital heart disease (CHD) representing a particularly high-risk subset compared with cardiomyopathy. Many of these early failures were related to poor patient selection, suboptimal immunosuppression and technical problems. We learned a great deal from these earlier difficulties. Presently, with more refined techniques, better-defined patient selection criteria, excellent graft rejection monitoring and optimal immunosuppression, the ISHLT 2011 registry reported a 10-year survival rate of 60% for patients transplanted for end-stage CHD and >70% for those transplanted for cardiomyopathy. The technical dilemmas in complex CHD were overcome by surgical ingenuity and creativity, innovative solutions and careful surgical planning, adapting the complex recipient anatomy to the normal donor anatomy. The miniaturized Berlin Heart pulsatile ventricular assist devices in children as a bridge to transplantation have revolutionized treatment and become a significant contribution in heart-failure therapy. The intramyocardial electrogram and echocardiographic strain rate imaging have been employed as non-invasive techniques of rejection monitoring. Immunosuppressive drugs have a major impact on the development and progression of cardiac allograft vasculopathy, the main cause of cardiac allograft loss and a leading cause of mortality after the first year post-transplantation. The questions of whether a transplanted heart in a newborn grows to adult size along with the child and whether the dimensional cardiac growth allows adequate function over time have been largely answered in our previous investigations. As more transplanted children reach adulthood, concerns about their life expectancy when they have reached 10 years of life post-transplant are raised, particularly with respect to establishing partnerships and families, their ability to earn a living and the fulfilment of personal life perspectives. Some heart-transplanted patients require retransplantation to remain alive. The disparity between the demand for and supply of donor hearts makes retransplantation an ethical issue. We 'do not refuse' any patient who needs retransplantation. Mechanical circulatory support devices for long-term use are now largely available to accommodate such cases.

Is heart transplantation for complex congenital heart disease a good option? A 25-year single centre experience

OBJECTIVES

Heart transplantation (HTx) in patients with complex congenital heart disease (CHD) is a challenge because of structural anomalies and multiple previous procedures. We analysed our results in adult and paediatric patients to evaluate outcome and assess risk factors affecting mortality.

METHODS

Between 1985 and 2011, among 839 patients who underwent HTx, 85 received transplantation for end-stage CHD. Patients were divided into four age subgroups: <1 year (8 patients, Group I), 1-10 years (20 patients, Group II), 11-18 years (24 patients, Group III) and >18 years (33 patients, Group IV) and into two time periods: 1985-2000 (47 patients) and 2001-2011 (38 patients). Anatomical diagnoses were single-ventricle defect in 37 patients (44%) and two-ventricle defect in 48 patients (56%). Seventy-three patients (86%) had undergone one or more cardiac surgical procedures prior to HTx (mean 2.4 ± 0.9). Twenty-two of them were suffering from Fontan failure. Mean pulmonary artery pressure was 25.2 ± 14.2 mmHg. Mean transpulmonary gradient was 9.4 ± 6.9 mmHg.

RESULTS

Mean follow-up after HTx was 7.8 ± 6.8 years. Survival at 1 month was 37.7% in Group I, 85.8% in Group II, 96.8% in Group II and 98.4% in Group IV and was significantly worse in younger recipients. Overall 30-day mortality was 17.6%. Currently 56 patients (65.8%) are alive. Overall survival at 1, 5, 10 and 15 years is 83-, 73-, 67- and 58%, respectively. There were 14 late deaths. Univariate analysis found that risk factors for early and late death were those related to recipient illness, such as pre-transplant creatinine, intravenous inotropic drugs, intravenous diuretics, mechanical ventilation and presence of protein-losing enteropathy (PLE). Multivariate analysis for all events (early and late deaths) identified preoperative mechanical ventilation as an independent risk factor for mortality. Number of previous procedures did not influence survival. Previous Fontan procedure did not increase mortality. We documented the reversibility of PLE in survivors.

CONCLUSIONS

We demonstrated that heart transplantation for patients with CHD can be performed with the expectation of excellent results. Previous procedures, including the Fontan operation, do not reduce survival. Mortality is related to preoperative patient condition. We advocate early referral of complex CHD patients for transplant assessment and for inclusion in waiting lists before the detrimental effects of end-stage failure manifest themselves.