Should status II patients be removed from the pediatric heart transplant waiting list? A multi-institutional study

More lessons learned from the Pediatric Heart Transplant Study

Paediatric heart transplantation has evolved over the last 3 decades. The research group, Pediatric Heart Transplant Study, has been in step with that evolution over the nearly 20 years of its existence by utilising its registry to contribute a wealth of clinical research to the field. The highlights of its studies will be presented in this review.

Too high for transplantation? Single-center analysis of the lung allocation score

BACKGROUND

Recent studies using United Network for Organ Sharing data suggest that lung transplantation in patients with high lung allocation scores (LAS) may lead to organ and resource wastage. Therefore, to determine whether a LAS cutoff value should be considered, we evaluated the relation of LAS to waitlist and posttransplant mortality in our center to determine if it could identify patients for whom listing for transplantation may be futile.

METHODS

From May 1, 2005 to July 1, 2010, 537 adults were listed and 426 underwent primary lung transplantation at our institution. Endpoints were mortality before and after lung transplantation. The relationships of LAS at listing to waitlist mortality and of pretransplant LAS to posttransplant mortality were both analyzed by multiphase hazard function methodology.

RESULTS

Higher LAS was strongly associated with waitlist mortality (p<0.0001), with the highest quartile (LAS ranging from 47 to 95) experiencing 75% mortality within a year of listing. Although early (p=0.05), but not late (p=0.4), posttransplant survival was associated with higher LAS at transplantation, once other clinical characteristics predictive of early mortality were accounted for, neither waitlist nor pretransplant LAS was independently related to posttransplant mortality (p=0.12).

CONCLUSIONS

Higher LAS strongly predicts higher mortality on the lung transplantation waitlist, underscoring the value of LAS in prioritizing patients with the highest scores for transplantation. Early posttransplant mortality is modestly higher with higher pretransplant LAS, but the data of our center do not suggest a value above which transplantation should be denied as futile. This suggests that donor organs and resources are not being wasted.

Ten yr of pediatric heart transplantation: a report from the Pediatric Heart Transplant Study

The PHTS was founded in 1991 as a not-for-profit organization dedicated to the advancement of the science and treatment of children during listing for and following heart transplantation. Now, 21 yr later, the PHTS has contributed significantly to the field, most notably in the form of outcomes analyses and risk factor assessment, in addition to amassing the most detailed dataset on pediatric heart transplant recipients worldwide. The purpose of this report is to review the last decade of pediatric patients listed for heart transplantation (January 1, 2000-December 31, 2009) and summarize the changes, trends, outcomes, and lessons learned.

Peak oxygen uptake correlates with survival without clinical deterioration in ambulatory children with dilated cardiomyopathy

BACKGROUND

Children stable at home with dilated cardiomyopathy remain at risk of death; there is evidence of survival benefit for transplantation out to 4 years postoperatively. The limited supply of donor organs makes risk stratification imperative, but although cardiopulmonary exercise test is well established as a powerful tool in adults with heart failure, no published studies have linked oxygen uptake to prognosis in children.

METHODS AND RESULTS

Between 2001 and 2009, using cardiopulmonary exercise test and echocardiography, we studied 82 children (mean age, 13.5±2.3 years) with dilated cardiomyopathy. All were ambulatory, outpatients, and >120 cm in height. All children completed a symptom-limited maximal exercise test. Resting left ventricular shortening fraction was 20±9%; peak heart rate was 87±13% of predicted; peak oxygen uptake (VO(2)) was 67±22% of predicted; and ventilatory efficiency was 32±8. Follow-up was available for 100% of the children, and was a mean of 32.3±7.5 months. Eighteen patients reached the defined clinical end point of death or listing for urgent heart transplantation. On univariate analysis, left ventricular shortening fraction, peak heart rate, peak VO(2), peak systolic blood pressure, and ventilatory efficiency were all associated with adverse outcome. On multivariable Cox analysis, only peak VO(2) (P=0.003) was associated with the study end point. Patients with a peak VO(2) ≤62% of predicted had a higher 24-month event rate (50.6% versus 4.4%; hazard ratio, 10.78).

CONCLUSIONS

We have demonstrated that a cardiopulmonary exercise test is feasible in ambulatory children with dilated cardiomyopathy who are >120 cm height and for the first time have linked peak VO(2) with outcome in children.

The impact of heart failure severity at time of listing for cardiac transplantation on survival in pediatric cardiomyopathy

BACKGROUND

The survival benefit of heart transplantation in adult heart failure is greatest for the sickest patients and negligible for patients not requiring inotropic or mechanical support. We hypothesized a similar survival benefit of heart transplantation for childhood cardiomyopathies with heart failure.

METHODS

A merged data set of children registered in both the Pediatric Cardiomyopathy Registry and the Pediatric Heart Transplant Study was used to assess differences in mortality before and after transplant in patients with different levels of heart failure severity. Severity was scored 2 if mechanical ventilatory or circulatory support was required, 1 if intravenous inotropes were required, or 0 if no support was required.

RESULTS

For 332 eligible children, 12-month mortality after listing was 9% for those with a severity score of 0 (n = 105), 16% with a score of 1 (n = 118), and 26% with a score of 2 (n = 109; p = 0.002) with a 3%, 8%, and 20% mortality with severity scores at listing of 0, 1, and 2, respectively, occurring before transplant. Patients listed with a score of 0 frequently deteriorated: 50% received an allograft or died before transplant with severity scores of 1 or 2. The risk of deterioration increased with previous surgery (relative risk, 3.84; p = 0.03) in the short-term and with lower left ventricular mass z-score at time of presentation (relative risk, 1.74; p = 0.003) in the longer-term.

CONCLUSION

Pediatric cardiomyopathy patients who require high levels of support receive a survival benefit from heart transplantation that is not shared by patients not requiring intravenous inotropic or mechanical support.

Heart transplantation for heart failure in children

Heart transplantation has become standard therapy for end-stage heart failure in children with cardiomyopathy as well as complex congenital heart disease, and has a significant effect on survival and quality of life. The indications for listing and referral for transplantation are outlined. Evaluation for heart transplantation is discussed, including full pretransplant assessment. ABO incompatible listing and HLA sensitization are discussed, and listing algorithms are outlined for different countries.

Cost-effectiveness of implantable cardioverter-defibrillators in children with dilated cardiomyopathy

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) improve survival and are cost-effective in adults with poor left ventricular function. Because of differences in heart failure etiology, sudden death rates, and ICD complication rates, these findings may not be applicable to children.

METHODS AND RESULTS

We developed a Markov model to compare typical management of childhood dilated cardiomyopathy with symptomatic heart failure to prophylactic ICD implantation plus typical management. Model costs included costs of outpatient care, medications, complications, and transplantation. Time horizon was up to 20 years from model entry. Total costs were $433,000 (ICD strategy) and $355,000 (typical management). Although quality adjusted survival was greater in the ICD group (6.78 versus 6.43 quality adjusted life-years [QALY]), the incremental cost-utility ratio was $281,622/QALY saved with the ICD strategy. In sensitivity analyses, the ICD strategy cost less than the $100,000/QALY benchmark for cost-effectiveness only when the annual probability of sudden death exceeded 13% or when strong, sustained benefits in quality of life from the ICD were assumed.

CONCLUSIONS

Prophylactic ICD use in children with dilated cardiomyopathy, poor ventricular function, and symptomatic heart failure does not appear to be cost-effective. This is likely due to lower sudden death rates in this population.

Outcome of pediatric patients with dilated cardiomyopathy listed for transplant: a multi-institutional study

BACKGROUND

The course of dilated cardiomyopathy (DCM) leading to heart failure in children varies; survival with conventional treatment is 64% at 5 years. Heart transplantation (HTx) enables improved survival; however, outcomes from listing for transplant are not well described. This study reports survival of patients with DCM from listing with the availability of mechanical bridge to transplant.

METHODS

Patients with a primary diagnosis of DCM (n = 1,098) were identified from a multi-institutional, prospective, registry of patients aged < 18 years listed for HTx from January 1, 1993, to December 31, 2006.

RESULTS

Characteristics of DCM patients at listing included a mean age of 7.3 years; 51% male, 64% white ethnicity, 77% United Network for Organ Sharing status I, 66% on inotropic support, 28% mechanically ventilated, and 15% on mechanical support. Waitlist mortality was 11%, and 75% underwent HTx at 2 years after listing. Overall 10-year survival after listing was 72%, with higher risk of death associated with arrhythmias, mechanical ventilation, and extracorporeal membrane oxygenation (ECMO) support, but not ventricular assist device (VAD) support. Survival at 10 years post-HTx was 72%, with a higher risk of death associated with black race, older age, mechanical ventilation, longer ischemic time, and earlier era of transplant.

CONCLUSIONS

Transplantation for DCM in the pediatric population offers enhanced survival compared with the natural history. Overall waitlist mortality for DCM is low, with the exception of patients on ECMO, mechanically ventilated, or with arrhythmias. DCM patients fared well after transplant, making HTx a key therapeutic intervention.

Improved Survival of Patients With End-Stage Heart Failure Listed for Heart Transplantation

OBJECTIVES

We sought to investigate the actual survival of patients with end-stage heart failure listed for heart transplantation (HT) in the U.S.

BACKGROUND

The United Network of Organ Sharing (UNOS) reported that the mortality rates on the U.S. HT waiting list have been gradually declining. This suggests that the survival of these patients may have improved.

METHODS

The survival censored on the day of HT or removal from the waiting list was calculated for 18,004 UNOS status 1 and 30,978 status 2 candidates listed in eras I (1990 to 1994), II (1995 to 1999), and III (2000 to 2005) in the U.S. The Cox proportional model was employed for multivariable analysis.

RESULTS

The 1-year survival on the HT waiting list improved from 49.5% to 69.0% for status 1 and from 81.8% to 89.4% for status 2 candidates between eras I and III. The predictors of death within 2 months from listing of status 1 candidates included UNOS status 1A, mechanical ventilation, inotropic and intra-aortic balloon pump support, pulmonary capillary wedge pressure >20 mm Hg and serum creatinine >1.5 mg/dl, failed HT, valvular cardiomyopathy, age >60 years, Caucasian ethnicity, and weight < or =70 kg, as well as the lack of intracardiac cardioverter-defibrillator on the day of listing.

CONCLUSIONS

Survival of HT candidates on the waiting list has significantly improved. Survival of status 1 candidates continues to depend on urgent HT. Predictors of 2-month mortality may help identify status 1 candidates who warrant the highest priority for HT and/or mechanical circulatory support. The 1-year survival of status 2 candidates approaches outcomes of HT, thus raising the question of whether early listing of some of these patients is justified.

Indications for Heart Transplantation in Pediatric Heart Disease

Background— Since the initial utilization of heart transplantation as therapy for end-stage pediatric heart disease, improvements have occurred in outcomes with heart transplantation and surgical therapies for congenital heart disease along with the application of medical therapies to pediatric heart failure that have improved outcomes in adults. These events justify a reevaluation of the indications for heart transplantation in congenital heart disease and other causes of pediatric heart failure.

Methods and Results— A working group was commissioned to review accumulated experience with pediatric heart transplantation and its use in patients with unrepaired and/or previously repaired or palliated congenital heart disease (children and adults), in patients with pediatric cardiomyopathies, and in pediatric patients with prior heart transplantation. Evidence-based guidelines for the indications for heart transplantation or retransplantation for these conditions were developed.

Conclusions— This evaluation has led to the development and refinement of indications for heart transplantation for patients with congenital heart disease and pediatric cardiomyopathies in addition to indications for pediatric heart retransplantation.