Adult-age donors offer acceptable long-term survival to pediatric heart transplant recipients: an analysis of the United Network of Organ Sharing database

Donor-Derived Cell-Free DNA to Diagnose Graft Rejection Post-Transplant: Past, Present and Future

Donor-derived cell-free DNA (dd-cfDNA) is a non-invasive biomarker that is more sensitive and specific towards diagnosing any graft injury or rejection. Due to its applicability over all transplanted organs irrespective of age, sex, race, ethnicity, and the non-requirement of a donor sample, it emerges as a new gold standard for graft health and rejection monitoring. Published research articles describing the role and efficiency of dd-cfDNA were identified and scrutinized to acquire a brief understanding of the history, evolution, emergence, role, efficiency, and applicability of dd-cfDNA in the field of transplantation. The dd-cfDNA can be quantified using quantitative PCR, next-generation sequencing, and droplet digital PCR, and there is a commendatory outcome in terms of diagnosing graft injury and monitoring graft health. The increased levels of dd-cfDNA can diagnose the rejection prior to any other presently used biochemistry or immunological assay methods. Biopsies are performed when these tests show any signs of injury and/or rejection. Therefore, by the time these tests predict and show any unusual or improper activity of the graft, the graft is already damaged by almost 50%. This review elucidates the evolution, physiology, techniques, limitations, and prospects of dd-cfDNA as a biomarker for post-transplant graft damage and rejection.

Adult heart transplant: indications and outcomes

Cardiac transplantation is the treatment of choice for many patients with end-stage heart failure (HF) who remain symptomatic despite optimal medical therapy. For carefully selected patients, heart transplantation offers markedly improved survival and quality of life. Risk stratification of the large group of patients with end-stage HF is essential for identifying patients who are most likely to benefit, particularly as the number of suitable donors is insufficient to meet demand. The indications for heart transplant and review components of the pre-transplant evaluation, including the role for exercise testing and risk scores such as the Heart Failure Survival Score (HFSS) and Seattle Heart Failure Model (SHFM) are summarized. Common contraindications are also discussed. Outcomes, including survival and common complications such as coronary allograft vasculopathy are reviewed.

Regional variation in survival before and after pediatric heart transplantation--an analysis of the UNOS database

Geographic variation occurs in a variety of health outcomes. Regional influences on outcomes before and after listing for pediatric heart transplantation have not been assessed. Review of the UNOS dataset identified 5398 pediatric (≤ 18 years) patients listed for heart transplantation 2000-2011. Patients were stratified based on the region of listing. Regional-level variables were correlated with individual risk-adjusted outcomes. Mean time spent on the waitlist varied from 91.0 ± 163 days (Region 6 [R6]) to 248.1 ± 493 days (R4, p < 0.0001). Regions with more transplant centers (p < 0.0001) and fewer transplants (p = 0.0015) had higher waitlist mortality. Risk-adjusted individual waitlist mortality varied from 6.9% (R1, CI 6.2-7.8) to 19.2% (R5, CI 18.0-20.6). Waitlist mortality was higher for individuals awaiting transplant in regions with more listings per center (OR 1.04, CI 1.01-1.08) and lower in regions with more donors per center (OR 0.95, CI 0.90-0.99 per donor). Posttransplant risk-adjusted survival varied across regions (R4: 5.4%, CI 4.2-7.4; R7: 18.0%, CI 12.4-32.5), but regional variables were not correlated with outcomes. Outcomes among children undergoing heart transplantation vary by region. Factors leading to increased competition for donor allografts are associated with poorer waitlist survival. Equitable allocation of cardiac allografts requires further investigation of these findings.

Multiple risk factors before pediatric cardiac transplantation are associated with increased graft loss

Identification of heart transplant recipients at highest risk for a poor outcome could lead to improved posttransplantation survival. A chart review of primary heart transplantations from 1993 to 2006 was performed. Analysis was performed to evaluate the risk of graft loss for those with a transplantation age less than 1 year, congenital heart disease (CHD), elevated pulmonary vascular resistance (index > 6), positive panel reactive antibody or crossmatch, liver or renal dysfunction, mechanical ventilation, or mechanical circulatory support (MCS). Primary transplantation was performed for 189 patients. Among these patients, 37% had CHD, 23% had mechanical ventilation, and 6% had renal dysfunction. Overall graft survival was 82% at 1 year and 68% at 5 years. The univariate risk factors for graft loss included mechanical ventilation (hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.15-3.18), CHD (HR, 1.68; 95% CI, 1.04-2.70), and renal dysfunction (HR, 3.05; 95% CI, 1.34-6.70). The multivariate predictors of graft loss were CHD (HR, 1.8; 95% CI, 1.02-2.64), mechanical ventilation (HR, 1.9; 95% CI, 1.13-3.10), and the presence of two or more statistically significant univariate risk factors (SRF) (HR, 3.8; 95% CI, 2.00-7.32). Mechanical ventilation, CHD, and the presence of two or more SRFs identify pediatric patients at higher risk for graft loss and should be considered in the management of children with end-stage heart failure.

Listing and Transplanting Adults With Congenital Heart Disease

Background—

An increasing number of patients with congenital heart disease (CHD) are reaching adulthood and may require heart transplantation. The survival of these patients after listing and transplantation has not been evaluated.

Methods and Results—

A total of 41 849 patients (aged >18 years) were listed for primary transplantation during 1995–2009. Patients with a history of CHD (n=1035; 2.5%) were compared with those with other causes (non-CHD group) (n=40 814; 97.5%); 26 055 (62.3%) reached transplantation and were subdivided into those with (reoperation group; n=10 484; 40.2%) and without (nonreoperation group; n=15 571; 59.8%) a previous sternotomy. Survival on the waiting list was similar between groups, but mechanical ventricular assistance was not associated with superior survival to transplantation among CHD patients. CHD patients were more likely to have body mass index <18.5 at transplantation ( P <0.0001), were younger, and had fewer comorbidities. Early mortality among patients with CHD was high (reoperation, 18.9% versus 9.6%; P <0.0001; nonreoperation, 16.6% versus 6.3%; P <0.0001), but by 10 years, overall survival was equivalent (53.8% versus 53.6%). Analysis was limited by the lack of specific information regarding the CHD diagnosis in most patients.

Conclusions—

Adults with CHD have high 30-day mortality but better late survival after heart transplantation. Mechanical circulatory assistance does not improve waiting list survival in these patients. This may be due to a combination of highly complex reoperative surgery and often poor preoperative systemic health.