Heart transplant donation after circulatory death: current status and implications

Understanding preservation time thresholds in the modern era of heart transplantation

A 4-h preservation time threshold for cardiac allografts is the current standard in heart transplantation, but novel technologies are proposed to decrease the morbidity associated with prolonged allograft storage. This study examined adult heart transplant recipients from 2000-2015 and 2020-2023 in the United States, stratified into an early (2000-2015) and modern era (2020-2023), then into standard (≤ 4 h) and prolonged (≥ 5 h) preservation time groups within each era. This study reinforced the 4-h threshold in the early era, where prolonged preservation significantly increased one-year mortality (HR 1.60, 95% CI 1.36-1.90). However, this association was no longer significant in the modern era (HR 1.14, 95% CI 0.85-1.50). A sub-analysis showed that using machine perfusion devices for allograft storage was not associated with one-year mortality (HR 1.15, 95% CI 0.79-1.70). Spline analysis demonstrated possible inflection points between 4 and 5 h and 8-9 h in the modern era, and further analysis found that 5-8 h of preservation did not increase one-year mortality (HR 1.09, 95% CI 0.80-1.47) relative to the ≤ 4 h group. In conclusion, the association between cardiac allograft preservation duration and morbidity has decreased in the modern era. Today, a 4-h preservation duration threshold may be too restrictive.

Revolutionizing Donor Heart Procurement: Innovations and Future Directions for Enhanced Transplantation Outcomes

Heart failure persists as a critical public health challenge, with heart transplantation esteemed as the optimal treatment for patients with end-stage heart failure. However, the limited availability of donor hearts presents a major obstacle to meeting patient needs. In recent years, the most groundbreaking progress in heart transplantation has been in donor heart procurement, significantly expanding the donor pool and enhancing clinical outcomes. This review comprehensively examines these advancements, including the resurgence of heart donation after circulatory death and innovative recovery and evaluation technologies such as normothermic machine perfusion and thoraco-abdominal normothermic regional perfusion. Additionally, novel preservation methods, including controlled hypothermic preservation and hypothermic oxygenated perfusion, are evaluated. The review also explores the use of extended-criteria donors, post-cardiopulmonary resuscitation donors, and high-risk donors, all contributing to increased donor availability without compromising outcomes. Future directions, such as xenotransplantation, biomarkers, and artificial intelligence in donor heart evaluation and procurement, are discussed. These innovations promise to address current limitations and optimize donor heart utilization, ultimately enhancing transplantation success. By identifying recent advancements and proposing future research directions, this review aims to provide insights into advancing heart transplantation and improving patient outcomes.

Heart Transplantation

Heart transplantation (HTx) remains the last therapeutic resort for patients with advanced heart failure. The present work is a clinically focused review discussing current issues in heart transplantation. Several factors have been associated with the outcome of HTx, such as ABO and HLA compatibility, graft size, ischemic time, age, infections, and the cause of death, as well as imaging and laboratory tests. In 2018, UNOS changed the organ allocation policy for HTx. The aim of this change was to prioritize patients with a more severe clinical condition resulting in a reduction in mortality of people on the waiting list. Advanced heart failure and resistant angina are among the main indications of HTx, whereas active infection, peripheral vascular disease, malignancies, and increased body mass index (BMI) are important contraindications. The main complications of HTx include graft rejection, graft angiopathy, primary graft failure, infection, neoplasms, and retransplantation. Recent advances in the field of HTx include the first two porcine-to-human xenotransplantations, the inclusion of hepatitis C donors, donation after circulatory death, novel monitoring for acute cellular rejection and antibody-mediated rejection, and advances in donor heart preservation and transportation. Lastly, novel immunosuppression therapies such as daratumumab, belatacept, IL 6 directed therapy, and IgG endopeptidase have shown promising results.