Faculty Bibliography

BACKGROUND:Porcine genome editing has revolutionized xenotransplantation, recently enabling the first pig-to-human heart xenotransplants. However, the xeno-immune response in heart xenografts remains largely unexplored. This study aimed to precisely characterize the xeno-immune response and injury in two heart xenografts, transplanted from 10-gene-edited pigs into brain-dead human recipients. METHODS:We analyzed xenograft biopsies at 66-hour post-reperfusion using a multimodal phenotyping approach combining: morphological evaluation, immunophenotyping, ultrastructural assessment, automated quantification of multiplex immunofluorescence staining and gene expression profiling. Xenografts before implantation and wild-type pig hearts with and without ischemia reperfusion injury and brain death were used as controls. RESULTS:Both xenografts showed evidence of endothelial activation and mild microvascular inflammation without capillary C4d deposition. Immune infiltrates were mainly composed of CD15+ and CD68+ innate immune cells. Ultrastructural assessment showed endothelial swelling with occasional intravascular leucocytes. Deep-learning based automated multiplex immunofluorescence analysis confirmed that microvascular inflammation was primarily associated with CD15+ and CD68+ innate immune cells. Both xenografts showed increased expression of genes and pathways associated with monocyte/macrophage activation, neutrophil activation, interferon-gamma response, natural killer cell burden, endothelial activation, apoptosis and injury repair. This phenotype was absent in all control pig hearts, independently from ischemia reperfusion injury and brain death. CONCLUSIONS:Multimodal phenotyping of pig-to-human heart xenografts revealed early signs of xeno-immune response, characterized by mild innate microvascular inflammation, endothelial activation, and molecular signature characteristic of antibody-mediated rejection. Developing such precision diagnostic system could improve graft monitoring in future clinical settings.

Cardiogenic shock (CS) remains a high-mortality condition that demands rapid diagnosis, coordinated multidisciplinary management, and timely initiation of mechanical circulatory support. As more institutions implement dedicated CS teams, substantial heterogeneity has emerged in how these teams are structured, activated, and sustained. To better characterize this variability and begin defining the components of an optimal CS team, the Society of Critical Care Cardiology (SoCCC), in partnership with the Society for Cardiovascular Angiography and Interventions (SCAI), convened the Inaugural Cardiogenic Shock Teams Think Tank. Held on October 17, 2024, as a pre-conference program to SCAI SHOCK 2024 in Washington, DC, the meeting brought together national leaders in CS care, mechanical circulatory support, and resuscitation to identify shared challenges and propose practical solutions. This manuscript summarizes key insights from this inaugural Think Tank, which represents the first in an ongoing series of collaborative efforts aimed at informing the standardization and optimization of CS teams nationwide. Specifically, we review the ideal composition and core competencies of a CS team; the rationale and emerging evidence supporting dedicated team-based CS care; activation algorithms and operational workflows; and common barriers to establishing and sustaining such teams. We also outline future directions and opportunities to strengthen collaborative infrastructure, refine clinical pathways, and enhance the reliability, responsiveness, and effectiveness of cardiogenic shock teams across diverse healthcare settings.

CLINICAL CONDITION/UNASSIGNED:The authors present the case of a young man who presented with cardiogenic shock requiring venoarterial extracorporeal membrane oxygenation and microaxial flow pump complicated by acute spinal cord infarction (SCI) leading to bilateral lower extremity paraplegia. KEY QUESTIONS/UNASSIGNED:The key questions included the following: 1) What is the incidence and pathophysiology for SCI with mechanical circulatory support (MCS)?; 2) Which configurations of MCS carry a greater risk of SCI? How do we approach MCS escalation, recognizing that with each device we carry additive risk of complications?; 3) What data guide anticoagulation strategies for MCS?; and 4) What strategies can we implement to support patients who have suffered SCI from MCS? OUTCOME/RESULTS:Our patient was transitioned to a right ventricular assist device with Impella 5.5 as a bridge to therapy, and underwent cardiac transplantation 4 weeks after presentation with ongoing inpatient rehabilitation. TAKE-HOME MESSAGES/CONCLUSIONS:Contemporary MCS carries a small but significant risk of SCI which is often irreversible. More data are required to guide anticoagulation strategies for MCS and mitigate risk.

BACKGROUND/UNASSIGNED:Donation after circulatory death (DCD) with cardiopulmonary bypass for thoracoabdominal normothermic regional perfusion (TA-NRP) has led to increased use of donor hearts. Rejection rates and long-term survival outcomes are not known. METHODS/UNASSIGNED:A single-center retrospective cohort review of patients who underwent DCD heart transplantation from January 2020 to December 2023 was performed. Donor and recipient characteristics, operative characteristics, and posttransplantation outcomes were analyzed. Subgroup analysis comparing co-localized vs distant donors and recipients was performed. The primary end point was 1-year survival. Secondary end points included incidences of primary graft dysfunction (PGD), cardiac allograft vasculopathy (CAV), rejection rate, and overall mortality. Our TA-NRP protocol has remained the same, consisting of sternotomy, ligation of aortic arch vessels, establishment of cardiopulmonary bypass, reintubation, resuscitation of the heart, and cold static storage during transport. RESULTS/UNASSIGNED:< .005) ischemia times, without any other differences. CONCLUSIONS/UNASSIGNED:Outcomes after DCD heart transplantation using TA-NRP remain encouraging with acceptable rates of rejection, PGD, CAV, and survival at 1 year.

BACKGROUND:In the 2018 Organ Procurement and Transplantation Network donor heart allocation system, patients listed for re-transplantation due to cardiac allograft vasculopathy (CAV) are assigned to Status 4 unless hemodynamic criteria are met. We aim to examine waitlist outcomes of CAV patients among adult heart transplant candidates. METHODS:We examined waitlist mortality stratified by CAV and waitlist status among adult heart transplant candidates using Scientific Registry of Transplant Recipients data from 10/1/2018-11/1/2023. We analyzed waitlist mortality using Kaplan-Meier curves and doubly-robust Cox regressions adjusted for age, gender, sex, race, and dialysis. We compared CAV to non-CAV patients by initial waitlist status, first status of interest, and time-dependent status. RESULTS:Of 21,586 listed patients, 368 were listed for CAV. CAV patients were most often listed at Status 4 with lower proportions at Status 3/2/1 compared with non-CAV patients. Status 4 and Status 3 CAV candidates demonstrated higher than expected waitlist mortality compared to non-CAV counterparts (Status 4: HR 0.51, 95% CI 0.31-0.84; p < 0.01; Status 3: HR 0.61, 95% CI 0.23-1.64; p = 0.33) with similar mortality to non-CAV patients in Status 3 and 2, respectively (Status 4: HR 0.80, 95% CI 0.48-1.35; p = 0.4; Status 3: HR 1.07, 95% CI 0.40-2.86; p = 0.89). When stratifying by status tier, CAV waitlist patients ever listed at Status 4 and 3 had a higher probability of death compared to their non-CAV counterparts (Status 4: HR 1.99, 95% CI 1.20-3.31, p < 0.01; Status 3: HR 3.06, 95% CI 1.06-8.87, p = 0.04). CONCLUSIONS:After 2018, CAV patients had a higher risk of waitlist mortality at Status 4 and 3 compared to non-CAV patients. These results suggest that CAV patients are underprioritized in the current allocation system.

PURPOSE/OBJECTIVE:Cardiac rehabilitation (CR) is beneficial in heart transplant and left ventricular assist device (LVAD) recipients, but patterns of attendance remain poorly understood. We describe CR adherence and cessation in this population. METHODS:We performed a retrospective review of heart transplant and LVAD recipients who attended ≥1 CR session at a tertiary medical center (2013-2022). Complete adherence was defined as attending 36 sessions. Primary reasons for cessation before 36 sessions were recorded. We compared post-operative complications, duration of hospitalization, and readmissions between participants with and without complete adherence using logistic and linear regressions. Among participants with complete adherence, we compared changes in metabolic equivalent of task (MET), exercise time, and peak oxygen uptake using paired sample t tests. RESULTS:There were 137 heart transplant and LVAD recipients (median age 56.9 years, 74% male) who attended CR. Among them, 91% either completed 36 CR sessions or <24 sessions. Among those without complete adherence (n = 74), 72% reported medical reasons, and 15% reported personal reasons for cessation. Compared to those who completed CR, those without complete adherence experienced more post-operative complications (44% vs 24%, P = .02) and major bleeding (23% vs 7%, P = .02) prior to CR. Participants with complete adherence experienced significant improvements in exercise time (142.5 seconds), MET (0.4), and peak oxygen uptake (1.4 mL/kg/min). CONCLUSIONS:Nearly half of heart transplant and LVAD recipients in CR completed all 36 sessions. Those with complete adherence experienced significant improvements in exercise measures, underscoring the important benefits of CR in this population.

Radial artery occlusion (RAO), a complication of transradial access, has an incidence of 4.0% to 9.1% in patients with advanced chronic kidney disease (CKD) and may preclude its use creation of arteriovenous fistula. Distal transradial access (dTRA) has lower rates of RAO compared with TRA, but prior studies excluded patients with advanced CKD. This was a single center study of patients with advanced CKD who underwent coronary procedures with dTRA from January 1, 2019 to May 12, 2022 who were retrospectively evaluated for radial artery patency in follow-up with reverse Barbeau testing or repeat access of the artery. Of 71 patients, 66% were on hemodialysis and the remainder had CKD 3 to 5. Access was ultrasound-guided, and all received adequate spasmolytic therapy and patent hemostasis. Proximal radial arteries were patent in 100% of the patients at follow-up. Our data suggest that dTRA is safe for patients with advanced CKD and preserves radial artery patency.

BACKGROUND:Because of advances in medical treatment of heart failure, patients are living longer than in previous eras and may approach the need for advanced therapies, including heart transplantation, at older ages. This study assesses practices surrounding heart transplant in older adults (> 70 years) and examines short- and medium-term outcomes. METHODS AND RESULTS/RESULTS:This study is a retrospective analysis using the United Network for Organ Sharing (UNOS) database from 2010 to 2021. The absolute number of older adults being transplanted is increasing. Older adults were more likely to have had a prior malignancy or ischemic cardiomyopathy and less likely to be on extra-corporeal membrane oxygenation or have a high UNOS status prior to transplant. Mortality at 1-year was higher for older adults (27.8% vs. 23.4%), but at 5 years there was no significant difference (22.3% vs. 19.4%.). Older adults were more likely to die of malignancy or infection. Adults under 70 were more likely to die of cardiovascular causes or graft failure. There was less rejection in older adults. Mortality has not changed for older adults transplanted before versus after the 2018 UNOS allocation change. CONCLUSIONS:Carefully selected older adults may be considered for heart transplantation, given similar intermediate-term mortality.