The International Society for Heart and Lung Transplantation (ISHLT) Guidelines for the Care of Heart Transplant Recipients

Development and validation of a clinical prediction model for dialysis-requiring acute kidney injury following heart transplantation: a single-center study from China

OBJECTIVES

This study seeks to construct and internally validate a clinical prediction model for predicting new-onset dialysis-requiring acute kidney injury (AKI) following heart transplantation (HT).

METHODS

The Kaplan-Meier survival analysis and log-rank test were utilized for conducting the survival analysis. A clinical prediction model was developed to predict postoperative dialysis-requiring AKI, based on a logistic regression model and likelihood ratio test with Akaike Information Criterion. The performance of the prediction model was assessed using C-index, receiver operating characteristic curves, calibration curves, Brier score, and the Spiegelhalter Z-test. Clinical utility was evaluated using decision curve analysis and clinical impact curves.

RESULTS

This study included a total of 525 patients who underwent orthotopic HT in the single center located in Wuhan, China between January 2015 and December 2021, with 16.57% developing postoperative dialysis-requiring AKI. Patients who experienced postoperative dialysis-requiring AKI exhibited a lower overall survival rate. All enrolled participants were randomly allocated into derivation (n = 350) and validation (n = 175) cohorts at a ratio of 2:1. The final prediction model comprised six indicators: diabetes, stroke, gout, prognostic nutritional index, estimated glomerular filtration rate, and cardiopulmonary bypass duration. The prediction model demonstrated outstanding discrimination (C-index of 0.792 in the derivation cohort and 0.834 in the validation cohort) as well as calibration performance, indicating strong concordance between observed and nomogram-predicted probabilities. Subgroup analysis based on age, preoperative serum creatine levels, and year of surgery also exhibited robust discrimination and calibration capabilities.

CONCLUSIONS

Dialysis-requiring AKI following HT is associated with poor clinical prognosis. The prediction model, comprising six indicators, is capable of predicting dialysis-requiring AKI following HT. This prediction model holds promise in assisting both patients and clinicians in forecasting postoperative renal failure, thereby improving clinical management.

CLINICAL TRIAL NUMBER

Not applicable.

Quantitative Stress First-Pass Perfusion Cardiac MRI: State of the Art

Quantitative stress perfusion (qPerf) cardiac magnetic resonance (CMR) imaging is a noninvasive approach used to quantify myocardial blood flow (MBF). Compared with visual analysis, qPerf CMR has superior diagnostic accuracy in the detection of myocardial ischemia and assessment of ischemic burden. In the evaluation of epicardial coronary artery disease (CAD), qPerf CMR improves the distinction of single-vessel from multivessel disease, yielding a more accurate estimate of the ischemic burden, and in turn improving patient management. In patients with chest pain without epicardial CAD, the findings of lower stress MBF and myocardial perfusion reserve (MPR) allow the diagnosis of microvascular dysfunction (MVD). Given its accuracy, MBF quantification with stress CMR has been introduced into the most recent recommendations for diagnosis in patients who have ischemia with nonobstructive CAD. Recent studies have shown a greater decrease in stress MBF and MPR in patients with three-vessel CAD compared with those in patients with MVD, demonstrating an important role that quantitative stress CMR can play in differentiating these etiologies in patients with stable angina. In cases of hypertrophic cardiomyopathy and cardiac amyloidosis, qPerf CMR aids in early diagnosis of ischemia and in risk assessment. Ischemia also results from alterations in hemodynamics that may occur with valve disease such as aortic stenosis or in cases of heart failure. qPerf CMR has emerged as a useful noninvasive tool for detection of cardiac allograft vasculopathy in patients who have undergone heart transplant. The authors review the basic principles and current primary clinical applications of qPerf CMR. ©RSNA, 2025 Supplemental material is available for this article. See the invited commentary by Leung and Ng in this issue.

Donor age and ischemic time in heart transplantation - implications for organ preservation

BACKGROUND

The Organ Care System and Non-ischemic Heart Preservation methods have emerged as significant advancements in heart transplantation, designed to mitigate ischemic injury and extend preservation times. However, their high costs and logistical complexities necessitate strategic utilization.

METHODS

We evaluated data from 83,761 heart transplants registered in the International Society for Heart and Lung Transplantation registry from 1988 to 2018. Utilizing a Cox proportional hazards model, we explored the influence of donor age and ischemic time on transplant survival. A key innovation of our study is the development of a nomogram to predict post-transplant survival, incorporating both traditional and advanced statistical methods.

RESULTS

The median age of recipients was 52 years (22% female) and 33 years (31% female) for donors. Analysis revealed a median ischemic time of 3 hours and median survival of 11.5 years across the cohort. The nomogram showed a decline in survival probabilities with increasing donor age, notably from age 40 and more significantly with ischemic times >4 hours. Ischemic times ≥4 hours versus <2 hours were associated with hazard ratio (HR) of 1.2 (95% CI, 1.1-1.3) for donors aged 40-59, a disparity that escalated for donors aged ≥60 (HR: 2.0; 95% CI, 1.5-2.7).

CONCLUSIONS

This study highlights the importance of careful donor selection and indicates that certain groups, particularly older donors with prolonged ischemic times, might benefit from ex-vivo preservation techniques. The developed nomogram offers a practical tool for clinicians, enhancing decision-making by providing detailed insights into the relationship between donor age, ischemic time, and post-transplant mortality.

Multimodal Inpatient Prehabilitation Prior to Heart or Lung Transplantation in a Latin American Transplant Reference Center

INTRODUCTION

Whether the implementation of a multimodal prehabilitation program is effective and safe for high-risk heart or lung transplantation candidates, whose condition prevents hospital discharge, is unclear.

METHODS

We conducted a retrospective study at a cardiothoracic transplant center in Chile. Two cohorts of hospitalized patients listed for heart or lung transplant were studied: the first underwent traditional (historical) and nonstructured prehabilitation, and the second underwent protocol-driven multimodal prehabilitation (MP). Adverse events and preoperative functional changes in the MP group were documented, as well as comparative postoperative outcomes between both cohorts.

RESULTS

Between 2018 and 2023, 24 transplant recipients were analyzed. During the MP phase, significant improvement was observed in Medical Research Council scale (52.0 ± 7 to 58.7 ± 3; P = .042), sit-to-stand test (7.1 ± 7 to 15.9 ± 6; P = .018), and euthymic state (from 4 to 10 patients; P .036), without reported adverse events. Postoperatively, MP group demonstrated faster standing (1.9 ± 0.7 vs 1.3 ± 0.5 days; P = .05) and sitting times (2.0 ± 0.7 vs 1.2 ± 0.5 days; P = .007), with more early extubations (3 vs 11; P = .003) in comparison to the historical prehabilitation cohort.

CONCLUSION

In this small retrospective study, MP in hospitalized patients awaiting heart or lung transplantation appears to be safe and associated with improvements in pre- and postoperative outcomes.

The effect of proteasome in heart transplantation: From mechanisms to therapeutic potential

Heart transplantation is a critical treatment for end-stage heart failure. However, its clinical efficacy is hindered by some challenges, such as ischemia-reperfusion injury (IRI) and post-transplant rejection. These complications significantly contribute to graft dysfunction and compromise patient survival. Emerging evidence underscores the involvement of proteasome in the pathophysiology of both IRI and post-transplant rejection. Proteasome inhibition has demonstrated potential in attenuating IRI by limiting oxidative damage and apoptosis while also mitigating rejection through the regulation of adaptive and innate immune responses. Recent advances in the development of proteasome inhibitors, particularly in optimizing specificity and minimizing adverse effects, have further strengthened their prospects for clinical application. This review focuses on the roles of the proteasome and its inhibitors in heart transplantation, with an emphasis on their mechanisms and therapeutic applications in managing IRI and rejection.

Useful central mechanical circulatory support system for critical biventricular heart failure associated with high pulmonary vascular resistance

BACKGROUND

Peripheral veno-arterial extracorporeal membrane oxygenation (ECMO) is a powerful life-saving tool; however, it can sometimes induce severe pulmonary edema in patients with critical heart failure. We report favorable outcomes in critically ill patients by using a central ECMO system with an innovative blood perfusion method.

METHODS

We analyzed 10 patients with severe heart failure and pulmonary edema who were treated with the central ECMO system at our institution between April 2022 and October 2023. The system consists of central cannulation with two inflows from the right atrium and left ventricle, and two outflows to the aorta and pulmonary artery, connected by two Y-connectors to a single ECMO circuit (RALV-AOPA ECMO). In this system, blood flow to the pulmonary artery is adjusted and mean pulmonary artery pressure is limited to <20 mm Hg, which reduces right ventricular afterload and prevents the worsening of pulmonary edema and hemorrhage.

RESULTS

Six patients were diagnosed with fulminant lymphocytic myocarditis, and four were diagnosed with coronavirus disease 2019-related myocardial injury. The ejection fraction was 6.5 ± 4.1%. The average intraoperative pulmonary vascular resistance was 4.6 ± 1.3 Wood units. After 24 h, the mean pulmonary arterial pressure was 12.8 ± 4.3 mm Hg, and pulmonary vascular resistance was 1.5 ± 0.3 Wood units. The duration of central RALV-AOPA ECMO was 3.7 ± 2.1 days. Finally, six patients were weaned, three received HeartMate3, and one received heart transplantation. At follow-up, all patients remained alive (428 ± 208 days), and two patients experienced cerebrovascular accidents without any lasting sequelae.

CONCLUSIONS

The central RALV-AOPA ECMO is an innovative system that achieves early improvement in pulmonary vascular resistance and is safe and feasible for patients with acute biventricular failure and pulmonary edema.

Management of heart disease in renal transplant recipients: a national Delphi survey-based SET/SEC/SEN consensus document

Renal transplantation improves the survival and quality of life of patients with end-stage renal disease. Cardiovascular disease is the leading cause of morbidity and mortality in renal transplant recipients. The bidirectional relationship between renal and heart disease creates a unique clinical scenario that demands a comprehensive and personalized approach. This expert consensus, drafted by the Spanish Society of Transplantation, the Spanish Society of Cardiology, and the Spanish Society of Nephrology, aims to assess current practices and propose strategies for the management of heart disease in renal transplant recipients. A panel of Spanish nephrologists and cardiologists with expertise in renal and heart transplantation reviewed the scientific evidence concerning the current management of heart disease in renal transplant recipients. Subsequently, consensus statements were created through a 2-round Delphi methodology, resulting in 30 statements covering key topics such as the identification of renal transplant candidates, the management of heart disease in renal transplant recipients, and eligibility for combined heart-kidney transplantation in patients with both end-stage renal disease and cardiac disease. These consensus statements provide expert guidance for the management of heart disease in renal transplant recipients, an area where published clinical evidence remains limited.

Progress of Angiographic Cardiac Allograft Vasculopathy in Patients With Long-Term Transplantation: Longitudinal Evaluation of Its Association With Dyslipidemia Patterns

Cardiac allograft vasculopathy (CAV) is a progressive disease with limited options for secondary prevention. Ways to manage lipid parameters and dyslipidemia patterns in care after transplantation remain unclear. In this longitudinal study, we included 32 patients with long-term heart transplantations (median interval after transplant 13.8 years) with angiographic manifest CAV. In 299 matched nonstented segments at 3 distinct time points ([TPs] 0 to 2, with median intervals of 2 years, respectively), progress of diameter stenosis (Δ%DS) defined CAV progress. Values above the median of maximal Δ%DS defined substantial CAV progress. Category of left ventricular ejection fraction was evaluated at TP0 and TP3 (2 years after TP2). Findings were correlated with dyslipidemia patterns at TP0, and lipid variations at follow-up (TP1 to TP3). Analyses included routine lipid assessment, and triglycerides/high-density lipoprotein-cholesterol ratio (TG/HDL-c) and atherogenic index of plasma (AIP). At TP1 and TP2, patients with increase of TG/HDL-c ≥0.1 (p = 0.02, respectively) and with increase of AIP (p = 0.01 and p = 0.049, respectively) presented a greater maximal Δ%DS. Dyslipidemia patterns at TP0 did not show a relevant association with CAV progress. At TP2, increase of TGs, TG/HDL-c, and AIP were associated with substantial CAV progress (odds ratio [OR] 5.0, p = 0.046, and OR 9.2, p = 0.01, OR 6.6, p = 0.02, respectively). At TP3, patients with CAV-related worsening of left ventricular ejection fraction category presented with a greater increase of TG/HDL-c (p = 0.03). Although findings at TP0 did not affect CAV progress, an increase of TG/HDL-c could define patients at greater risk of CAV progress and CAV-related deterioration of graft function.

Echocardiographic Evaluation of the Post-Heart Transplant Patient

PURPOSE OF REVIEW

Significant practice variability exists with respect to the role and frequency of echocardiography after heart transplantation. We sought to illustrate key studies relating to the utility and diagnostic accuracy of echocardiography for the post-heart transplant patient.

RECENT FINDINGS

Several echocardiographic parameters correlate with acute heart transplant rejection, but there is enough heterogeneity between study results or in diagnostic accuracy, such that it precludes parameter use in isolation to rule out rejection. Newer techniques such as strain echocardiography may have better sensitivity. Similarly, resting and stress echocardiography can be combined with modern techniques such as myocardial contrast echocardiography to diagnose and prognosticate cardiac allograft vasculopathy, but studies have again demonstrated variable accuracy. Echocardiography remains an accessible tool in the evaluation and management of patients after heart transplantation. This modality can guide clinical judgment with real-time data and several fairly sensitive parameters for the detection of rejection, cardiac allograft vasculopathy, and other abnormalities. Often, auxiliary diagnostic modalities need to be combined to optimize diagnostic accuracy.

A narrative review on the psychosocial domains of the impact of organ transplantation

This review explores organ transplantation, spanning historical developments, psychosocial impacts, and future directions. In the pre-transplantation phase, evaluations of psychosocial factors, including substance use, mental health, and social support, are essential for successful outcomes. However, linking total psychosocial risk scores to post-transplant outcomes remains challenging despite available tools and assessments. Patient selection criteria and psychological assessments are pivotal in achieving successful transplantation outcomes. The age of donors significantly impacts transplant outcomes across various organs, highlighting the urgency of addressing organ shortages. Meticulous patient selection, including thorough psychosocial evaluations, ensures recipients possess the necessary emotional resilience and support systems for successful transplantation. Both pre- and post-transplantation psychological evaluation processes are crucial for assessing and supporting individuals throughout the transplant journey. Posttransplant evaluations continue to monitor adjustment difficulties, medication adherence, and complex emotions, enabling timely intervention and personalized support. The waiting period before transplantation presents significant challenges, including uncertainty, anxiety, and social isolation. Robust emotional support and coping mechanisms are crucial during this transitional phase, fostering resilience and hope among waitlist candidates. Psychological challenges during and after transplantation, including anxiety, depression, and sleep disturbances, are common among recipients. Coping mechanisms, such as religious/spiritual approaches, social support, and participation in support groups, play pivotal roles in patient adjustment and recovery. Ethical considerations are paramount in ensuring fair and effective transplantation practices, including organ allocation, adherence to post-transplant care, financial burdens, and the interplay between medical and psychosocial factors.

Microvascular Resistance Reserve and Prognosis After Heart Transplantation

BACKGROUND

Impaired microcirculatory function after heart transplantation is associated with increased risk for acute cellular rejection. Microvascular resistance reserve (MRR) is a novel index for assessing microcirculatory function, irrespective of epicardial coronary artery stenosis, but it has not been validated in transplanted hearts.

OBJECTIVES

The aim of this study was to investigate the prognostic impact of MRR in heart transplantation.

METHODS

The present study prospectively enrolled 154 heart transplant recipients who underwent scheduled coronary angiography and invasive coronary physiological assessment 1 month after transplantation. Coronary microcirculatory dysfunction was defined as MRR ≤3.0. Elevated microcirculatory resistance was defined as an index of microcirculatory resistance ≥15. The presence of epicardial coronary stenosis was assessed by fractional flow reserve. The primary outcome was a composite of death or biopsy-proven acute cellular rejection of grade ≥ 2R after transplantation.

RESULTS

Among the total patients, 22.1% (34 of 154) had impaired microcirculatory function (MRR ≤3.0), and 77.9% (122 of 154) had preserved microcirculatory function (MRR >3.0). During median follow-up of 730 days (Q1-Q3: 730-730 days), patients with MRR ≤3.0 showed increased risk for a composite of death or acute cellular rejection (adjusted HR: 5.31; 95% CI: 2.65-10.64; P < 0.001), acute cellular rejection (adjusted HR: 4.83; 95% CI: 2.20-10.60; P < 0.001), and death (adjusted HR: 5.19; 95% CI: 1.24-21.62; P = 0.024). MRR was significantly associated with increased risk for death or acute cellular rejection, regardless of epicardial coronary artery stenosis (HR adjusted for fractional flow reserve: 1.89 per 1-U decrease in MRR; 95% CI: 1.46-2.46; P < 0.001) or elevated microcirculatory resistance (HR adjusted for index of microcirculatory resistance: 1.90 per 1-U decrease in MRR; 95% CI: 1.43-2.52; P < 0.001).

CONCLUSIONS

Impaired microcirculatory function, determined by MRR early after heart transplantation, identified patients at high risk for death or acute cellular rejection, regardless of epicardial coronary artery stenosis or elevated microcirculatory resistance. (Physiologic Assessment of Microvascular Function in Heart Transplant Patients; NCT02798731).

Care of Adult Heart Transplant Recipients by the Primary Care Provider: A Practical Roadmap

Heart transplantation has significantly improved survival and enhanced the quality of life of patients with end-stage heart failure. Successful long-term outcomes are predicated on a collaborative effort among patients, transplant teams, and primary care providers (PCPs). Notably, PCPs are increasingly pivotal in post-transplant care, engaging in annual assessments, early recognition of complications, and referral, thus minimizing morbidity and mortality. This article highlights key considerations for PCPs, including indications for heart transplant, immunosuppressive therapy and infection prophylaxis, management of post-transplant complications, psychosocial and lifestyle adjustment, and family planning. This roadmap aims to empower PCPs to deliver optimal care and improve long-term outcomes for heart transplant recipients.

Feasibility and Role of Cardiac Magnetic Resonance in Intensive and Acute Cardiovascular Care

Cardiac magnetic resonance (CMR) is established as a key imaging modality in a wide range of cardiovascular diseases and has an emerging diagnostic and prognostic role in selected patients presenting acutely. Recent technical advancements have improved the versatility of this imaging technique, which has become quicker and more detailed in both functional and tissue characterization assessments. Information derived from this test has the potential to change clinical management, guide therapeutic decisions, and provide risk stratification. This review aims to highlight the evolving diagnostic and prognostic role of CMR in this setting, whilst also providing practical guidance on which patients can benefit the most from CMR and which information can be derived from this test that will impact clinical management.

Management of Kidney Disease in Heart Transplant Patients: A National Delphi Survey-based Consensus Expert Paper

Kidney disease is a common complication in heart transplant recipients and requires a comprehensive and personalized approach. The interplay between preexisting kidney disease, perioperative factors, immunosuppression, and cardiovascular complications makes the management of kidney dysfunction challenging in these patients. The objective of this expert consensus was to look for agreements for the management of chronic kidney disease in heart transplant recipients. A panel of Spanish cardiologists and nephrologists with expertise in heart and kidney transplantation reviewed the evidence related to the current management of chronic kidney disease in heart transplant recipients and consensus statements were developed using a 2-round Delphi methodology. Consensus statements were proposed covering key topics, including the identification and management of kidney disease in heart transplant recipients and the indications for kidney transplantation. These statements provide additional expert guidance for the management of kidney disease in patients undergoing heart transplantation where published clinical evidence is scarce.

Whole genome sequencing in early onset advanced heart failure

The genetic contributions to early onset heart failure (HF) are incompletely understood. Genetic testing in advanced HF patients undergoing heart transplantation (HTx) may yield clinical benefits, but data is limited. We performed deep-coverage whole genome sequencing (WGS) in 102 Swedish HTx recipients. Gene lists were compiled through a systematic literature review. Variants were prioritized for pathogenicity and classified manually. We also compared polygenic HF risk scores to a population-based cohort. We found a pathogenic (LP/P) variant in 34 individuals (34%). Testing yield was highest in hypertrophic (63% LP/P carriers), dilated (40%) and arrhythmogenic right ventricular (33%) cardiomyopathy and lower in ischemic cardiomyopathy (10%). A family history was more common in LP/P variant carriers than in non-carriers but was present in less than half of carriers (44% vs 13%, P < 0.001), whereas age was similar. Polygenic risk scores were similar in HTx recipients and the population cohort. In conclusion, we observed a high prevalence of pathogenic cardiomyopathy gene variants in individuals with early-onset advanced HF, which could not accurately be ruled out by family history and age. In contrast, we did not observe higher polygenic risk scores in early onset advanced HF cases than in the general population.

Surveillance donor-specific antibody and pathologic antibody-mediated rejection testing in heart transplant patients in the contemporary era

BACKGROUND

Surveillance donor-specific antibody (DSA) and pathologic antibody-mediated rejection (pAMR) testing is recommended in the first year after heart transplantation (HTx) in adult patients. Whether pAMR testing adds prognostic information to contemporary DSA testing has not been fully studied.

METHODS

This was a single-center study of consecutive endomyocardial biopsies (EMB) performed between November 2010 and February 2023 in adult HTx patients. The primary objective was to evaluate whether pAMR testing contributes additional information to DSA testing to better predict overall survival. Secondary end-points included cardiac survival and allograft dysfunction.

RESULTS

A total of 6,033 EMBs from 544 HTx patients were reviewed for the study. The pAMR+/DSA+ patients had significantly lower overall (pc = 0.013) and cardiac survival (pc = 0.002), while the pAMR+/DSA- and pAMR-/DSA+ patients showed no difference in either outcome compared to the pAMR-/DSA- group. We found significantly lower overall survival in pAMR+/DSA+ patients with allograft dysfunction (pc < 0.001) but not in pAMR+/DSA+ patients without allograft dysfunction (pc = 0.569), when compared to the pAMR-/DSA- without allograft dysfunction group. The pAMR+/DSA+ patients with cardiac allograft dysfunction accounted for 18% of deaths or cardiac retransplants while only representing 4% of the HTx cohort. Moderate or severe primary graft dysfunction (PGD) also was a novel risk factor for the development of de novo DSAs (dnDSA) by 4 weeks post-HTx (p = 0.025).

CONCLUSIONS

Surveillance DSA testing may effectively identify high-risk pAMR+ patients. Earlier DSA testing at 10 to 14 days post-HTx should also be considered in moderate or severe PGD patients.

PET/CT with Myocardial Blood Flow Assessment Is Prognostic of Cardiac Allograft Vasculopathy Progression and Clinical Outcomes

Cardiac allograft vasculopathy (CAV) causes impaired blood flow in both epicardial vessels and microvasculature and remains a leading cause of posttransplant morbidity and mortality. This study examined the prognostic value and outcomes of CAV, assessed by 13N-ammonia PET/CT myocardial perfusion imaging in heart transplant recipients. Methods: PET/CT and invasive coronary angiography (ICA) were graded using validated scales. CAV progression was assessed using intrapatient sequences: baseline ICA, interval PET/CT with myocardial blood flow reserve, and subsequent ICA. Intervals between ICAs of 600, 900, and 1200 d were included, and for each, the negative predictive value (NPV) of CAV development was assessed. Results: In total, 344 heart transplant recipients underwent PET/CT for CAV assessment with a median follow-up of 4.8 y. PET CAV grade 0/1 had an NPV of 0.93, 0.95, and 0.95 at each respective time point for developing an International Society for Heart and Lung Transplantation CAV 2/3 on subsequent ICA. Compared with PET CAV 0, PET CAV 2/3 was associated with a 2.9-fold increased risk of all-cause mortality (hazard ratio, 2.86; 95% CI, 1.36-6.00; P = 0.006). PET CAV 1 had a numerically increased risk (hazard ratio, 2.03; 95% CI, 0.99-4.15; P = 0.054). In a sensitivity analysis of 135 patients with stable International Society for Heart and Lung Transplantation CAV over successive ICA, PET CAV 2/3 remained associated with increased risk of death or retransplantation (hazard ratio, 3.20; 95% CI, 1.18-8.69; P = 0.03). Conclusion: Noninvasive CAV assessment by PET/CT and myocardial blood flow reserve provides prognostic information and robust NPVs for development of moderate to severe CAV over intervals up to 4 y. These data suggest that, for certain patients, intervals between invasive screenings may be extended.

Advancements in noninvasive techniques for transplant rejection: from biomarker detection to molecular imaging

Transplant rejection remains a significant barrier to the long-term success of organ transplantation. Biopsy, although considered the gold standard, is invasive, costly, and unsuitable for routine monitoring. Traditional biomarkers, such as creatinine and troponin, offer limited predictive value owing to their low specificity, and conventional imaging techniques often fail to detect early organ damage, increasing the risk of undiagnosed rejection episodes. Considering these limitations, emerging noninvasive biomarkers and molecular imaging techniques hold promise for the early and accurate detection of transplant rejection, enabling personalized management strategies. This review highlights noninvasive biomarkers that predict, diagnose, and assess transplant prognosis by reflecting graft injury, inflammation, and immune responses. For example, donor-derived cell-free DNA (dd-cfDNA) is highly sensitive in detecting early graft injury, whereas gene expression profiling effectively excludes moderate-to-severe acute rejection (AR). Additionally, microRNA (miRNA) profiling enhances the diagnostic specificity for precise AR detection. Advanced molecular imaging techniques further augment the monitoring of rejection. Fluorescence imaging provides a high spatiotemporal resolution for AR grading, ultrasound offers real-time and portable monitoring, and magnetic resonance delivers high tissue contrast for anatomical assessments. Nuclear imaging modalities such as single photon emission computed tomography and positron emission tomography, enable dynamic visualization of immune responses within transplanted organs. Notably, dd-cfDNA and nuclear medicine imaging have already been integrated into clinical practice, thereby demonstrating the translational potential of these techniques. Unlike previous reviews, this work uniquely synthesizes advancements in both noninvasive biomarkers and molecular imaging, emphasizing their complementary strengths. Biomarkers deliver molecular-level insights, whereas imaging provides spatial and temporal resolution. Together, they create a synergistic framework for comprehensive and precise transplant monitoring. By bridging these domains, this review underscores their individual contributions and collective potential to enhance diagnostic accuracy, improve patient outcomes, and guide future research and clinical applications in transplant medicine.

Rejection Surveillance After Heart Transplantation: Is Paired Noninvasive Testing the New Gold Standard?

Rejection surveillance after heart transplantation has traditionally relied on numerous endomyocardial biopsies, most of which occur during the first posttransplant year. With the introduction of gene expression profiling and, more recently, donor-derived cell-free DNA, a great proportion of surveillance is being performed noninvasively with both tests. Although patients have welcomed the use of paired testing because of the decreased risk and inconvenience, interpretation of both tests can sometimes be challenging, particularly when the test results are discordant. Growing evidence from both single-center experiences and large national databases has given insights that have allowed the field to operationalize dual testing and provide physicians with algorithms to approach paired testing. The increased use of noninvasive testing has also begun to challenge the role of biopsy as the gold standard for graft monitoring, not only for rejection but over the life of the heart transplant. In a growing number of circumstances, cell-free DNA not only may be a better means of assessing rejection but could also redefine how clinicians approach the diagnosis and even treatment of graft injury. As the heart transplant community garners more experience and generates more data, the current paradigms of heart transplant surveillance will continue to be challenged.

Early Use of Aspirin for Coronary Allograft Prophylaxis in Heart Transplant Recipients

BACKGROUND

Coronary allograft vasculopathy (CAV) remains a significant cause of morbidity and mortality after heart transplantation. The use of aspirin for CAV prophylaxis has recently garnered interest as a possible therapeutic adjunct in this setting.

METHODS

This 2-center retrospective cohort study included 372 patients who underwent heart transplantation between January 2009 and March 2018 and were stratified according to the commencement of aspirin during their index transplant admission. The primary outcome was the development of moderate or severe CAV (International Society for Heart and Lung Transplantation grade ≥2) at surveillance coronary angiography. Secondary endpoints included mortality at follow-up.

RESULTS

There were no differences in age, sex, and cause of heart failure. In the early aspirin group, the preponderant risk factors included use of ventricular assist devices, pretransplant smoking, and mild or moderate rejection. Multivariable analyses to assess for independent predictors of CAV development and mortality demonstrated that aspirin was associated with reduced mortality (adjusted hazard ratio = 0.19; 95% confidence interval, 0.08-0.47, P  < 0.01) and a trend toward a protective effect against the development of moderate or severe CAV (adjusted hazard ratio = 0.24; 95% confidence interval, 0.54-1.19; P  = 0.08).

CONCLUSIONS

In this retrospective risk-adjusted 2-center cohort study, early aspirin administration was associated with reduced risk of death and a trend toward a protective effect against CAV development. These findings warrant validation in prospective randomized trials.

Cardiac MRI in Heart Transplantation: Approaches and Clinical Insights

Orthotopic heart transplant (OHT) is a well-established therapy for end-stage heart failure that leads to improved long-term survival rates, with careful allograft surveillance essential for optimizing clinical outcomes after OHT. Unfortunately, complications can arise after OHT that can compromise the success of the OHT. Cardiac MRI is continually evolving, with a range of advanced techniques that can be applied to evaluate allograft structure and function. Understanding the unique features of cardiac MRI in OHT recipients, identifying findings suggestive of acute or chronic complications, and recognizing the limitations of this imaging modality are essential for accurate interpretation of cardiac MRI findings and subsequent clinical reporting. The authors address the anticipated postsurgical anatomy and functionality of the OHT. Emphasis is placed on the advanced functional and tissue characterization features that can be seen in the stable OHT recipient, including global longitudinal strain, late gadolinium enhancement, native T1 and T2 mapping, and extracellular volume fraction. Subsequently, the evidence for detection of acute cardiac allograft rejection with cardiac MRI comprehensive tissue characterization techniques and the role of quantitative myocardial perfusion for cardiac allograft vasculopathy screening are discussed, with reference to their comparative standard of reference screening tests, including endomyocardial biopsy, invasive coronary angiography, and myocardial rest and stress perfusion PET/CT. Cardiac MRI has been included in contemporary OHT management guidelines and therefore can be considered a complementary tool for allograft evaluation. The authors demonstrate the complementary role cardiac MRI can play in cardiac allograft surveillance, with clinical examples. ©RSNA, 2025 Supplemental material is available for this article. See the invited commentary by Agarwal in this issue.

Humoral and cellular response to SARS-CoV-2 mRNA vaccine in paediatric heart transplant recipients

Objective

The aim of this prospective cohort study is to analyse the humoral and cellular vaccine responses in paediatric heart transplant recipients (HTR, n = 12), and compare it with the response in healthy controls (HC, n = 14). All participants were 5-18 years old and vaccinated with mRNA vaccine against SARS-CoV-2 between December 2021 and May 2022.

Methods

The humoral response was measured by quantifying antibody titers against SARS-CoV-2 spike protein (anti-S). The T-lymphocyte phenotype and SARS-CoV2-specific CD4+ and CD8+ T-cell response was studied by multiparametric flow cytometry through peripheral blood mononuclear cells by the quantification of degranulation markers (CD107a) and intracellular cytokines (IFN-γ, TNF-α and IL-2) after in vitro stimulation with SARS-CoV-2 peptides from structural proteins (S, M, N, E) and non-structural viral proteins.

Results

After vaccination, humoral response was found in all HTR, although they showed lower levels of anti-S IgG compared to HC (p = 0.003). However, in terms of cellular response, no significant differences were obtained in the prevalence of responders and magnitude of responses between groups. In addition, anti-S IgG levels directly correlated with a higher SARS-CoV-2 specific T-cell response (rho = 0.43; p = 0.027 and rho = 0.45; p = 0.02 for IFN-γ+ and TNF-α+ production of CD8+ T-cells, respectively). Activated T-cell phenotype in HTR was associated with a lower humoral response to SARS-CoV-2 vaccine.

Conclusion

HTR had humoral response after vaccination, although they showed lower levels of specific anti-S antibodies compared to HC. There were no significant differences in the SARS-CoV2-specific cellular response between the two groups. Obtaining satisfactory data on this type of response could potentially challenge the current vaccine guideline recommendations.

Persisting Gaps in Cytomegalovirus Prevention and Management After Solid Organ Transplantation in a Resource-Limited Setting

BACKGROUND

Cytomegalovirus (CMV) infection remains among the leading complications after solid organ transplantation (SOT). Large international surveys mainly focused on high-income countries, detected considerable variability in the management of this infection after SOT. Limited data are available from resource-limited settings.

METHODS

A questionnaire-based cross-sectional study was performed. All transplant programs (TP) registered at the Brazilian Organ Transplantation Society (ABTO) were invited to participate.

RESULTS

Sixty-one TP participated in the study. Of these, 59 (97%) reported using at least 1 preventive strategy (prophylaxis or preemptive therapy [PET]). Prophylaxis was reported by only 39 (64%). PET was used by 52 (85%), predominantly for R+ recipients (n = 42/61; 70%). CMV monitoring was performed weekly in only 22 of 52 (42%) TP. This was significantly more common in TP reporting turnaround times ≤72 h for quantitative nuclear acid amplification tests (p < 0.001). Intravenous (IV) ganciclovir was the predominant drug chosen for prophylaxis (21/39 TP; 54%) and for PET (44/52 TP; 77%). Lack of regular access to valganciclovir was significantly associated with the choice of IV ganciclovir for prophylaxis and PET (p = 0.002 for both comparisons). Only 8 (13%) TP had access to molecular diagnostic tests for ganciclovir resistance, and 14 (23%) had access to effective therapy for highly resistant infections.

CONCLUSION

These results suggest that strategies to improve the management of CMV after SOT in such a resource-limited setting are needed and should include not only targeted educational programs but also initiatives to tackle economic and structural barriers.

Nuclear Cardiology Surrogate Biomarkers in Clinical Trials

Nuclear cardiology offers a diverse range of imaging tools that provide valuable insights into myocardial perfusion, inflammation, metabolism, neuroregulation, thrombosis, and microcalcification. These techniques are crucial not only for diagnosing and managing cardiovascular conditions but also for gaining pathophysiologic insights. Surrogate biomarkers in nuclear cardiology, represented by detectable imaging changes, correlate with disease processes or therapeutic responses and can serve as endpoints in clinical trials when they demonstrate a clear link with these processes. By providing early indicators of therapeutic efficacy-often before clinical outcomes manifest-surrogate biomarkers can accelerate treatment development. This disease-focused review will highlight key nuclear cardiology surrogate biomarkers, emphasizing the importance of standardized imaging protocols and robust quantitative techniques to ensure accuracy and reproducibility. We will also explore the challenges to the broader adoption of imaging biomarkers, including the need for well-defined pathophysiologic correlations, greater data diversity in clinical research, and overcoming regulatory barriers. Addressing these challenges will improve the utility of imaging biomarkers in clinical trials, enabling more precise cardiovascular care through early diagnosis and therapeutic monitoring, ultimately accelerating the development of novel cardiovascular therapies.

Clinical Management and Transplant Considerations in Pediatric Pulmonary Hypertension Due to Left Heart Disease: A Scientific Statement From the American Heart Association

Children with left heart disease are at risk for developing pulmonary hypertension, initially secondary to pulmonary venous hypertension that can progress to include elevated pulmonary vascular resistance, known as combined pre- and postcapillary pulmonary hypertension. Elevated pulmonary vascular resistance may pose a risk to the right ventricle of a newly transplanted heart because of increased afterload and is an important consideration for heart transplant eligibility. However, the epidemiology, pathophysiology, optimal diagnostic and treatment approaches, and thresholds for pulmonary vascular resistance in pulmonary hypertension associated with left heart disease remain unclear because of lack of evidence, particularly in pediatrics. The result is heterogeneity with respect to hemodynamic assessment, use of pulmonary vasodilator therapies, and heart transplant listing. This scientific statement aims to synthesize the available data and highlight areas of general consensus as well as important knowledge gaps.

The outcome of restrictive cardiac allograft physiology in severe coronary allograft vasculopathy

BACKGROUND

Microvascular dysfunction after heart transplantation leads to restrictive cardiac allograft physiology (RCP), which is classified as severe coronary allograft vasculopathy (CAV); however, the prognosis of RCP remains unclear. Therefore, in this study, we aimed to elucidate the prognosis of RCP in comparison with that of severe angiographic CAV.

METHODS

We assessed 116 patients with severe CAV who underwent heart transplantation between 2004 and 2023. RCP was defined as symptomatic heart failure with restrictive hemodynamic values (mean right atrial pressure >12 mm Hg, pulmonary capillary wedge pressure >25 mm Hg, and cardiac index <2.0 liter/min/m2). The primary outcome was death or retransplantation.

RESULTS

Of the 116 patients with severe CAV, 42 had RCP (RCP-CAV group) and 74 had severe angiographic CAV without RCP (Angio-CAV group). A significantly shorter time from heart transplantation to diagnosis and lower subsequent percutaneous catheter intervention after diagnosis were seen in the RCP-CAV group than in the Angio-CAV group (both p < 0.001). Freedom from death or retransplantation at 5 years was significantly worse in the RCP-CAV group compared to the Angio-CAV group (18.4% vs 35.4%, p = 0.001). In the Cox proportional hazard model, RCP was independently associated with an increased risk of death or retransplantation (hazard ratio 2.08, 95% confidence intervals 1.26-3.44, p = 0.004).

CONCLUSIONS

The prognosis of patients with RCP was significantly worse than that of patients with severe angiographic CAV. The early detection of microvascular dysfunction and retransplantation listing may improve the prognosis of patients with RCP.

Risk of Post-Transplant Malignancy After Isolated Heart Transplant Among Adult Patients With Congenital Heart Disease

INTRODUCTION

Patients with congenital heart disease (CHD) are at increased risk of cancer. In patients with CHD and advanced heart failure, isolated heart transplantation (HT) can be considered. In the overall HT population, immunosuppression after HT increases the risk of post-transplant malignancy (PTM). However, cancer outcomes among adult HT patients with CHD have not been investigated.

METHODS

Patients aged ≥ 18 years who received HT between January 1, 2010 and December 31, 2021 were identified using the United Network for Organ Sharing (UNOS) registry. Patients with CHD were compared to those without. T primary outcome was a composite outcome of PTM or death due to malignancy. Multivariable Fine-Gray competing-risk regression was used to estimate the subhazard ratio (SHR) of primary and secondary outcomes.

RESULTS

Of the total of 29717 patients with HT were included, 1017 (3.4%) had CHD. Patients with CHD were younger, more likely to be female, and have had prior cardiac surgery. After multivariable competing-risk regression, CHD was associated with a higher risk of the primary outcome (SHR 1.43, 95% CI 1.15-1.80). Among patients who developed PTM, the median time to diagnosis of first PTM (median 36 vs. 46 months, p = 0.027) was shorter in patients with CHD. Among patients with CHD, survival after PTM was significantly lower compared with patients without malignancy (HR 3.32, 95% CI 2.03-5.43).

CONCLUSIONS

Among adult patients with HT, CHD was associated with an increased risk of PTM. Further investigation is warranted to identify risk factors and screening strategies for malignancy in this patient population.

High-risk Cytomegalovirus in Heart Transplant: How Can We Improve?

BACKGROUND

Cytomegalovirus (CMV) infection is associated with worse outcomes after heart transplant (HT). CMV mismatch (donor positive, recipient negative serology, D+/R-) increases the risk of infection. Guidelines recommend 3 to 6 months of antiviral prophylaxis in these patients. An increase in primary CMV infections at our center prompted us to analyses this population in search of improvement.

METHODS

From 185 adult HT receptors in 10 years, we selected those with CMV D+/R-. Patients were followed until October 2023. We evaluated the patterns of transmission of CMV in accordance with current recommendations.

RESULTS

We assessed 35 HT recipients with CMV mismatch (median age of 48.8 ± 13.8 years, 71% men). Median follow-up was 5.5 years [1.9-7.4]. Median duration of CMV prophylaxis was 3.7 (±2.1) months post-HT. CMV infection occurred in 74% of patients (96% within the first 6 months after ending prophylaxis) and CMV disease in 26%. Half of them required hospital admission. One third had concomitant infections by other microorganisms. There were no significant differences in the duration of prophylaxis between patients with and without CMV infection. Survival on follow-up was 77%. 2 patients died during CMV infection due to other infection.

CONCLUSIONS

CMV infection rate in D+/R- HT receptors remains high even after the prophylactic period recommended by current guidelines. A better knowledge of CMV-transmitted infection, coupled with the pursuit of a suitable equilibrium between the prevention of infection and rejection, have the potential to enhance the outcomes of this high-risk population through tailored protocols.

Redefining CAV surveillance strategies: Benefits of CCTA vs. ICA

BACKGROUND

Cardiac allograft vasculopathy (CAV) assessment post-heart transplantation (HT) typically relies on invasive coronary angiography (ICA). However, cardiac computed tomography angiography (CCTA) is emerging as a promising alternative due to its potential benefits in economic, safety, and logistical aspects. This study aimed to evaluate the impact of a CCTA program on these aspects in CAV surveillance post-HT.

METHODS

A retrospective single-center study was conducted between March 2021 and February 2023, involving HT patients who underwent either CCTA or ICA.

RESULTS

Among 260 patients undergoing CAV surveillance, 115 (44.2%) patients underwent CCTA, and 145 (55.8%) patients underwent ICA. The CCTA group showed incurred lower overall costs (p ​< ​0.0001) and shorter hospitalization times (p ​< ​0.0001) compared to the ICA group. In terms of safety, CCTA surveillance required significantly lower contrast volumes (p ​< ​0.0001) and lower effective doses (p ​= ​0.03).

CONCLUSION

CCTA emerges as a safe and cost-effective non-invasive alternative for CAV surveillance post-HT, outperforming ICA in terms of safety, logistical aspects, and economic burden.

Maintenance Immunosuppression With Tacrolimus and Everolimus in Heart Transplantation Compared With the Usual Tacrolimus and Micophenolate Protocol: Results From a Retrospective Registry

INTRODUCTION

Real-life data on the long-term use of a maintenance immunosuppressive protocol in heart transplant patients using delayed Everolimus + Tacrolimus are scarce.

METHODS

This is a retrospective study that included all heart transplant patients from 2011 to 2021 in two Spanish hospitals. In Hospital A, the preferred immunosuppressive strategy included Everolimus initiation at 2 months post-transplant combined with Tacrolimus and was compared with the results of Hospital B, where a standard Tacrolimus and Mycophenolate mofetil protocol was used. Incidence of cytomegalovirus infection, cardiac allograft vasculopathy, acute rejection, renal outcomes, infections, and survival were compared.

RESULTS

We studied 101 patients from Hospital A and 136 from Hospital B. Median follow-up was 4 years. We found no differences in the incidence of cytomegalovirus infection (P = .099), but the only two symptomatic cases occurred in Hospital B. No significant differences were found in the incidence of cardiac allograft vasculopathy (P = .322), although there was a trend toward earlier presentation in Hospital B. There was a tendency toward more rejection in patients from Hospital B (P = .051), but patients on Everolimus (Hospital A) had more bacterial infections (P = .013) and higher need for dyalisis or renal transplant (P = .004). 27% of patients on Everolimus required definite discontinuation due to side effects. There was no difference in survival after a median follow-up of 48 months.

CONCLUSIONS

Maintenance immunosuppression with delayed initiation of Everolimus in combination with Tacrolimus is considered a valid strategy in heart transplant patients, although discontinuation of Everolimus due to side effects is significant.

Clinical outcomes after a biopsy diagnosis of antibody-mediated rejection in pediatric heart transplant recipients

BACKGROUND

Extending survival after heart transplant (HT) is of paramount importance for childhood recipients of HT. Acute rejection is a significant event, and biopsy remains the most specific means for distinguishing between cellular (ACR) and antibody-mediated rejection (AMR).

METHODS

All children in the Pediatric Heart Transplant Society Registry who underwent HT between January 2015 and June 2022 and had ≥1 rejection episode were included. Survival was compared between AMR and ACR-only. Secondary outcomes of infection, malignancy, and cardiac allograft vasculopathy (CAV) were assessed. Risk factors for graft loss after AMR were identified using Cox proportional hazard modeling.

RESULTS

Among 906 children with rejection, 697 (77%) with complete biopsy information were included. AMR was present on biopsy in 261 (37%) patients; ACR-only was present in 436 (63%). Time to rejection was earlier for AMR, median time from HT to rejection 0.11 versus 0.29 years, p = 0.0006. Survival after AMR in the 1st year was lower than survival after ACR-only. Predictors of graft loss after AMR were younger age at HT, congenital heart disease, and rejection with hemodynamic compromise. There was no difference in time to CAV, infection, or malignancy after rejection between groups.

CONCLUSIONS

The largest analysis of pediatric HT rejection with biopsy data to identify AMR underscores the continued importance of AMR on survival. AMR is associated with higher graft loss versus ACR when occurring in the first-year post-HT. Predictors of graft loss after AMR identify patients who may benefit from increased surveillance or augmented maintenance immunosuppression.

Antifungal prophylaxis against invasive Candida and Aspergillus infection in adult heart transplant recipients: protocol for a systematic review and meta-analysis

INTRODUCTION

Invasive fungal infections (IFI) can contribute to increased mortality and morbidity rates after heart transplant in adults. The most common causes are Aspergillus and Candida species. There is uncertainty on how effective antifungal prophylaxis is against Candida spp infections and limited guidance on the prevention of Aspergillus spp infections. This systematic review and meta-analysis will assess the literature to see if antifungal prophylaxis reduces the incidence of IFI after heart transplant in adults.

METHODS AND ANALYSIS

This systematic review protocol follows the Preferred Reporting Items for Systematic reviews and Meta Analysis guidelines. A systematic search of the Cochrane Library, Web of Science, Scopus, Embase, MEDLINE, and Proquest databases will be undertaken. Reference lists of retrieved publications and conference abstracts will also be searched. Title, abstract and full-text screening will be undertaken by two reviewers. Discrepancies will be resolved by a third reviewer. Studies with paediatric patients, multi-organ transplants, or patients with a second heart transplant will be excluded, along with those who do not have clear definitions and diagnostic criteria for IFI. Risk of bias will be assessed using the Cochrane Risk of Bias 2 tool and the Risk of Bias in Non-randomised Studies of Interventions tool. A meta-analysis will be carried out, but if studies are not deemed to be sufficiently similar, only a narrative synthesis will be undertaken.

ETHICS AND DISSEMINATION

Ethical approval is not required for this systematic review as primary data will not be collected. The results of the review will be disseminated through publication in an academic journal and scientific conferences.

PROSPERO REGISTRATION NUMBER

CRD42024516588.

Can the grading of mild cardiac allograft vasculopathy be further refined? An angiographic and physiologic assessment of heart transplant recipients with ISHLT CAV 1

BACKGROUND

Cardiac allograft vasculopathy (CAV) results in impaired blood flow in both epicardial vessels and the microvasculature and is a leading cause of poor outcomes in heart transplant (HT) recipients. Most patients have mild (International Society for Heart and Lung Transplantation [ISHLT] CAV 1) disease. This study examined outcomes among those with ISHLT CAV 1 and investigated the value of physiologic assessment via cardiac positron emission tomography/computed tomography (PET/CT) for added risk stratification.

METHODS

CAV was graded using ISHLT criteria. Those with CAV 1 were further subgrouped into CAV 1a (maximal lesion <30% stenosis) or CAV 1b (maximal lesion ≥30% stenosis).

RESULTS

299 HT recipients underwent invasive coronary angiography for CAV assessment with a median follow-up of 4.7 years. ISHLT CAV 1 was associated with a 2.9-fold risk of death/retransplantation compared to ISHLT CAV 0 (95% confidence interval [CI] 1.7-5.3, p < 0.001). Of those with ISHLT CAV 1, 12% had ISHLT CAV 1b, which was associated with a 2.8 times greater risk of death/retransplantation compared to CAV 1a (95% CI 1.4-5.9, p = 0.003). In a subgroup of 158 patients with contemporary cardiac PET/CT, among those with CAV 1a, a myocardial blood flow reserve (MBFR) ≤2 was associated with a 4.6-fold risk of death/retransplantation compared to a normal MBFR (95% CI 1.7-12.6, p = 0.001).

CONCLUSION

Patients with CAV 1b had worse outcomes than those with CAV 1a. Among those with CAV 1a, the poorer outcomes than ISHLT CAV 0 observed were predominantly associated with reduced MBFR. These data suggest additional anatomic classification and physiologic assessment can further risk stratify those with ISHLT CAV 1.

Incidence and risk factors for rejection after conversion from calcineurin inhibitor to sirolimus-based immunosuppression in orthotopic heart transplant recipients

BACKGROUND

Although recommended in International Society for Heart and Lung Transplantation (ISHLT) guidelines, transition to mammalian targets of rapamycin (mTOR) inhibitors in heart transplant recipients is not routinely performed, in part due to perceived risk of rejection. This study sought to evaluate the incidence and risk factors for biopsy-proven, clinically relevant rejection following conversion from calcineurin inhibitor (CNI) to sirolimus (SRL) immunosuppression.

METHODS

A single center retrospective study was conducted of all consecutive adult patients who underwent orthotopic heart transplantation (OHT) and CNI-free SRL conversion from January 1999 to January 2023. All post-OHT biopsy data were obtained and graded per ISHLT criteria (antibody-mediated rejection [pAMR] or acute cellular rejection [ACR]). The primary endpoint was early rejection, defined as grade 2R ACR, pAMR 1, or greater, within 6 months after conversion.

RESULTS

317 patients (72% male, mean age 51.5 ± 12.6 years) were included. Median time to SRL conversion following OHT was 0.76 years (IQR 0.49, 1.42). Median time from conversion to rejection was 0.51 years (IQR 0.31, 1.05). 38 patients (12%) experienced early rejection. Following multivariate analysis, both timing to SRL conversion following OHT (OR 0.94 per month, 95% CI: 0.89-0.99, p-value = 0.0054) and age at transplantation (OR 0.96, 95% CI: 0.93-0.99, p-value = 0.0071) were independently associated with early rejection. Rejection following SRL conversion was not associated with increased risk of cardiac allograft vasculopathy (CAV) grade 2-3.

CONCLUSIONS

In a CNI-free SRL conversion protocol, both earlier SRL conversion following OHT and younger age at transplant are independently associated with early rejection, but rejection is not associated with a net increased risk of prognostically important CAV. Individualization of transition is necessary to mitigate risk, and these findings may aid in improvement of future conversion protocols.

In the Twilight of Evidence: Is Bypass Surgery Still on the Table for Cardiac Allograft Vasculopathy?

Background: Cardiac allograft vasculopathy (CAV) is a major prognosis-limiting factor in patients undergoing orthotopic heart transplantation (HT). Due to the diffuse involvement of the coronary tree, CAV lesions are often not amenable to percutaneous coronary intervention (PCI), leaving coronary artery bypass grafting (CABG) and retransplantation as primary revascularization options. Aim and Results: The latest guidelines from the International Society for Heart and Lung Transplantation (ISHLT) recognize CABG as a viable option but with a downgraded strength of recommendation. The 2023 ISHLT guidelines now categorize CABG as a Class IIb recommendation (Level of Evidence: C) for highly selected CAV patients with anatomically suitable lesions, a downgrade from the Class IIa recommendation in the 2010 guidelines. This adjustment underscores the persisting reliance on limited, retrospective studies and the lack of substantial new data supporting CABG in CAV management. Our article examines the evidence collected since 2010 on this topic, highlighting key findings and assessing the role of CABG in contemporary transplant practice. This article calls for targeted investigations to better define the role of CABG as a therapeutic option, addressing the gaps in evidence for surgical revascularization in HT patients.

Impact of donor obesity on outcomes of donation after circulatory death heart transplantation

BACKGROUND

In the setting of the obesity epidemic and donor organ shortage in the United States, there is a growing need to expand the donor organ eligibility criteria for orthotopic heart transplantation (OHT). Donation after circulatory death (DCD) has emerged as a promising solution, but the outcomes with obese donor hearts in DCD OHT remains unknown.

METHODS

Using the United Network for Organ Sharing registry between 2019 and 2024, recipients of DCD OHT were stratified into 3 donor obesity categories by body mass index (BMI): underweight/normal (BMI <25 kg/m2), overweight (BMI 25-30 kg/m2), and obese (BMI >30 kg/m2). These cohorts were subgrouped by organ procurement strategy: direct procurement and preservation (DPP) or normothermic regional perfusion (NRP). Recipient and donor characteristics and risk factors for mortality were analyzed using Cox regression hazard models. Survival at 30 days, 1 year, and 5 years post-transplantation were analyzed using the Kaplan-Meier method.

RESULTS

We found no significant differences in patient and graft survival between donor BMI categories at all time points. Among recipients of overweight (hazard ratio [HR], 0.38; P = .0371) and obese (HR, 0.24; P = .0493) donor hearts, NRP was associated with decreased risk of mortality. Donor-recipient predicted heart mass (PHM) undermatching (defined as <86%) was associated with increased risk of mortality among underweight/normal weight donors (HR, 1.28; P = .0323) and overweight donors (HR, 1.08; P = .0382).

CONCLUSIONS

Donor obesity does not confer an increased risk of recipient mortality in DCD OHT, particularly when NRP is used. PHM undermatching continues to be associated with adverse outcomes in DCD OHT.

Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO) Support in New Era of Heart Transplant

Heart failure is a serious and challenging medical condition characterized by the inability of the heart to pump blood effectively, leading to reduced blood flow to organs and tissues. Several underlying causes may be linked to this, including coronary artery disease, hypertension, or previous heart attacks. Therefore, it is a chronic condition that requires ongoing management and medical attention. HF affects >64 million individuals worldwide. Heart transplantation remains the gold standard of treatment for patients with end-stage cardiomyopathy. The recruitment of marginal donors may be considered an asset at the age of cardiac donor organ shortage. Primary graft dysfunction (PGD) is becoming increasingly common in the new era of heart transplantations. PGD is the most common cause of death within 30 days of cardiac transplantation. Mechanical Circulatory Support (MCS), particularly venoarterial extracorporeal membrane oxygenation (V-A ECMO), is the only effective treatment for severe PGD. VA-ECMO support ensures organ perfusion and provides the transplanted heart with adequate rest and recovery. In the new era of heart transplantation, early use allows for increased patient survival and careful management reduces complications.

Novel therapeutic agents for cardiometabolic risk mitigation in heart transplant recipients

Heart transplant (HT) recipients experience high rates of cardiometabolic disease. Novel therapies targeting hyperlipidemia, diabetes, and obesity, including proprotein convertase subtilisin/kexin inhibitors, sodium-glucose cotransporter-2 inhibitors, and glucagon-like peptide-1 agonists, are increasingly used for cardiometabolic risk mitigation in the general population. However, limited data exist to support the use of these agents in patients who have undergone heart transplantation. Herein, we describe the mechanisms of action and emerging evidence supporting the use of novel pharmacologic agents in the post-HT setting for cardiometabolic risk mitigation and review evidence supporting their ability to modulate immune pathways associated with atherogenesis, epicardial adipose tissue, and coronary allograft vasculopathy.

Immunoproteasome inhibition reduces donor specific antibody production and cardiac allograft vasculopathy in a mouse heart transplantation model

Objective

Cardiac Allograft Vasculopathy (CAV), a process of vascular damage accelerated by antibody-mediated rejection (AMR), is one of the leading causes of cardiac transplant failure. Proteasome inhibitors (PIs) are utilized to treat AMR, however PI-associated toxicity limits their therapeutic utility. Novel immunoproteasome inhibitors (IPIs) have higher specificity for immune cells and have not been investigated for AMR in cardiac transplant patients. We sought to evaluate IPI effect on AMR in a murine cardiac transplant model.

Methods

Fully MHC mismatched C57BL/6 to huCD52Tg heterotopic heart transplantations were performed. Recipients were treated with alemtuzumab (10 µg, IP) on days -2, -1, 2, and 4 and anti-CD25mAb (PC61, 100 µg, IP) on day 7 to accelerate AMR with or without IPI (ONX-0914,15 mg/kg, SQ), administered on transplant day and three times a week thereafter.

Results

Animals without IPI gradually developed post-transplant donor-specific antibody (DSA) and showed a significantly elevated DSA level compared to animals receiving IPI. (TFXM 48.86 vs. 14.17; p = 0.0291, BFXM 43.53 vs. 6.114; p = 0.0031). Accordingly, H&E staining of allograft showed reduced evidence of AMR with IPI compared to controls (P = 0.0410). Notably, increased mortality was observed in the IPI treated group.

Conclusion

This study demonstrated the ability of ONYX-0914, an IPI, to control post-transplant DSA production and the AMR development in a heart transplant model. However, IPI-resistant DSA production was also observed and increased mortality with IPI therapy raises concerns about potential toxicity. Further investigation is warranted to assess the utility and potential risk associated with the use of IPI as a post-transplant maintenance immunosuppression.

Left Atrial Functional and Structural Characteristics in Patients After Total and Bicaval Orthotopic Heart Transplantation

Background/Objectives: Currently, the most popular techniques for orthotopic heart transplantation (OHTx) are bicaval and total OHTx. Although bicaval OHTx has shown advantages over the biatrial approach, comparisons between bicaval and total OHTx reain limited. To compare the functional and morphological characteristics of the left atrium (LA) in patients after bicaval and total OHTx. Methods: Sixty-six patients (age 51.2 ± 10.5 years) after total OHTx (33 patients) and bicaval OHTx (33 patients) were included in this case-control study. Recipients were matched for sex, age, and time from transplantation and absence of severe graft rejection based on routine endomyocardial biopsies (EMB) performed during follow-up. Echocardiography included standard measurements along with a speckle-tracking assessment of LA strain. Results: Compared with the bicaval OHTx, the total OHTx group showed higher atrial mitral inflow velocity, resulting in a lower E/A ratio, lower LA volume index, and higher LA emptying fraction. Both the reservoir and contraction components of LA function, as assessed by LA deformation, were found to show more favorable profiles in the total OHTx group than in the bicaval group (26.5 ± 6.9 vs. 17.4 ± 4.7, p < 0.001 and 14.8 ± 5.8 vs. 6.0 ± 4.5, p < 0.001, respectively). Multivariable analysis identified surgical technique, left ventricular global longitudinal strain, and the presence of diabetes in the recipient as independent determinants of LA strain. Conclusions: Total OHTx is associated with better LA morphology and function than bicaval OHTx. This may provide better conditions for LA-LV coupling in transplanted hearts and contribute to a more stable electrophysiological environment in atrial tissue.

Donor HLA-DQ reactive B cells clonally expand under chronic immunosuppression and include atypical CD21 low CD27 - B cells with high-avidity germline B-cell receptors

Long-term allograft survival is limited by humoral-associated chronic allograft rejection, suggesting inadequate constraint of humoral alloimmunity by contemporary immunosuppression. Heterogeneity in alloreactive B cells and the incomplete definition of which B cells participate in chronic rejection in immunosuppressed transplant recipients limits our ability to develop effective therapies. Using a double-fluorochrome single-HLA tetramer approach combined with single-cell in vitro culture, we investigated the B-cell receptor (BCR) repertoire characteristics, avidity, and phenotype of donor HLA-DQ reactive B cells in a transplant recipient with end-stage donor specific antibody (DSA)-associated cardiac allograft vasculopathy while receiving maintenance immunosuppression (tacrolimus, mycophenolate mofetil, prednisone). Donor DQB1*03:02/DQA1*03:01 (DQ8)-reactive IgG+ B cells were enriched for minimally mutated and germline encoded high avidity BCRs (median K D 4.26×10 -09 ) with an atypical, antigen-experienced and proliferative phenotype (CD27 - CD21 low CD71 + CD11c +/- ). These B cells coexisted with a smaller subset of more highly mutated, affinity matured IgG+CD27+ B cells. Circulating donor-reactive B cells and DSA remained detectable after rituximab, contrasting with the marked reduction in DSA after allograft explant and retransplant. Together, these findings define the persistence of germline high-avidity HLA-DQ alloreactive B cells and their co-existence with affinity matured clones that were both driven by the allograft despite conventional immunosuppression.

Emerging role of circulating piRNAs in the diagnosis of heart transplant rejection

BACKGROUND

Liquid biopsy offers a potential alternative to decrease or eliminate endomyocardial biopsy for diagnosing allograft rejection. p-element-induced wimpy testis-interacting RNAs (piRNAs) are novel and promising disease biomarkers for their intrinsic characteristics such as stability in body fluids; however, their role in allograft rejection remains unexplored.

METHODS

A training set based on small RNA sequencing technology was performed to identify piRNAs in endomyocardial tissue (n = 8) and serum samples (n = 40) from patients following heart transplantation. A validation set of the potential piRNAs identified in the training study was conducted in an independent larger cohort for the detection of acute cellular rejection (ACR, n = 105) and antibody-mediated rejection (AMR, n = 61).

RESULTS

We identified 20,292 piRNAs in endomyocardial tissue and 24,602 piRNAs in serum samples from patients following heart transplantation. We identified 7 piRNAs with a coincident expression profile in both types of samples and potential capacity for the noninvasive detection of cardiac rejection. Validation in a large independent cohort demonstrated that a panel of these piRNAs showed excellent performance for detecting grade ≥2R ACR (area under the receiver operating characteristic curve [AUC] = 0.819; p < 0.0001) and grade 1R ACR (AUC = 0.721; p = 0.001). Furthermore, our piRNA panel showed a potential discrimination ability of pAMR2 (AUC = 0.967; p < 0.0001).

CONCLUSIONS

To the best of knowledge, this study is the first to report the presence of piRNAs in both endomyocardial tissue and serum samples of patients after heart transplant, including their association with allograft rejection events. We propose a novel piRNA panel for the detection of cardiac allograft rejection.