Report from a consensus conference on antibody-mediated rejection in heart transplantation

Targeting Macrophages in Organ Transplantation: A Step Toward Personalized Medicine

Organ transplantation remains the most optimal strategy for patients with end-stage organ failure. However, prevailing methods of immunosuppression are marred by adverse side effects, and allograft rejection remains common. It is imperative to identify and comprehensively characterize the cell types involved in allograft rejection, and develop therapies with greater specificity. There is increasing recognition that processes mediating allograft rejection are the result of interactions between innate and adaptive immune cells. Macrophages are heterogeneous innate immune cells with diverse functions that contribute to ischemia-reperfusion injury, acute rejection, and chronic rejection. Macrophages are inflammatory cells capable of innate allorecognition that strengthen their responses to secondary exposures over time via "trained immunity." However, macrophages also adopt immunoregulatory phenotypes and may promote allograft tolerance. In this review, we discuss the roles of macrophages in rejection and tolerance, and detail how macrophage plasticity and polarization influence transplantation outcomes. A comprehensive understanding of macrophages in transplant will guide future personalized approaches to therapies aimed at facilitating tolerance or mitigating the rejection process.

Outcome-based Risk Assessment of Non-HLA Antibodies in Heart Transplantation: A Systematic Review

BACKGROUND

Current monitoring after heart transplantation (HT) employs repeated invasive endomyocardial biopsies (EMB). Although positive EMB confirms rejection, EMB fails to predict impending, subclinical, or EMB-negative rejection events. While non-human leukocyte antigen (non-HLA) antibodies have emerged as important risk factors for antibody-mediated rejection after HT, their use in clinical risk stratification has been limited. A systematic review of the role of non-HLA antibodies in rejection pathologies has the potential to guide efforts to overcome deficiencies of EMB in rejection monitoring.

METHODS

Databases were searched to include studies on non-HLA antibodies in HT recipients. Data collected included the number of patients, type of rejection, non-HLA antigen studied, association of non-HLA antibodies with rejection, and evidence for synergistic interaction between non-HLA antibodies and donor-specific anti-human leukocyte antigen antibody (HLA-DSA) responses.

RESULTS

A total of 56 studies met the inclusion criteria. Strength of evidence for each non-HLA antibody was evaluated based on the number of articles and patients in support versus against their role in mediating rejection. Importantly, despite previous intense focus on the role of anti-major histocompatibility complex class I chain-related gene A (MICA) and anti-angiotensin II type I receptor antibodies (AT1R) in HT rejection, evidence for their involvement was equivocal. Conversely, the strength of evidence for other non-HLA antibodies supports that differing rejection pathologies are driven by differing non-HLA antibodies.

CONCLUSIONS

This systematic review underscores the importance of identifying peri-HT non-HLA antibodies. Current evidence supports the role of non-HLA antibodies in all forms of HT rejection. Further investigations are required to define the mechanisms of action of non-HLA antibodies in HT rejection.

Sex-specific patterns of donor-derived cell-free DNA in heart transplant rejection: An analysis from the Genomic Research Alliance for Transplantation (GRAfT)

BACKGROUND

Noninvasive methods for surveillance of acute rejection are increasingly used in heart transplantation (HT), including donor-derived cell-free DNA (dd-cfDNA). As other cardiac biomarkers differ by sex, we hypothesized that there may be sex-specific differences in the performance of dd-cfDNA for the detection of acute rejection. The purpose of the current study was to examine patterns of dd-cfDNA seen in quiescence and acute rejection in male and female transplant recipients.

METHODS

Patients enrolled in the Genomic Research Alliance for Transplantation who were ≥18 years at the time of HT were included. Rejection was defined by endomyocardial biopsy with acute cellular rejection (ACR) grade ≥2R and/or antibody-mediated rejection ≥ pAMR 1. dd-cfDNA was quantitated using shotgun sequencing. Median dd-cfDNA levels were compared between sexes during quiescence and rejection. The performance of dd-cfDNA by sex was assessed using area under the receiver operator characteristic (AUROC) curve. Allograft injury was defined as dd-cfDNA ≥0.25%.

RESULTS

One hundred fifty-one unique patients (49 female, 32%) were included in the analysis with 1,119 available dd-cfDNA measurements. Baseline characteristics including demographics and comorbidities were not significantly different between sexes. During quiescence, there were no significant sex differences in median dd-cfDNA level (0.04% [IQR 0.00, 0.16] in females vs 0.03% [IQR 0.00, 0.12] in males, p = 0.22). There were no significant sex differences in median dd-cfDNA for ACR (0.33% [0.21, 0.36] in females vs 0.32% [0.21, 1.10] in males, p = 0.57). Overall, median dd-cfDNA levels were higher in antibody-mediated rejection (AMR) than ACR but did not significantly differ by sex (0.50% [IQR 0.18, 0.82] in females vs 0.63% [IQR 0.32, 1.95] in males, p = 0.51). Elevated dd-cfDNA detected ACR/AMR with an AUROC of 0.83 in females and 0.89 in males, p-value for comparison = 0.16.

CONCLUSIONS

There were no significant sex differences in dd-cfDNA levels during quiescence and rejection. Performance characteristics were similar, suggesting similar diagnostic thresholds can be used in men and women for rejection surveillance.

Report of the 2022 Banff Heart Concurrent: Focus on non-human leukocyte antigen antibodies in rejection and the pathology of "mixed" rejection

The Banff Heart Concurrent Session, held as part of the 16th Banff Foundation for Allograft Pathology Conference at Banff, Alberta, Canada, on September 21, 2022, focused on 2 major topics: non-human leukocyte antigen (HLA) antibodies and mixed rejection. Each topic was addressed in a multidisciplinary fashion with clinical, immunological, and pathology perspectives and future developments and prospectives. Following the Banff organization model and principles, the collective aim of the speakers on each topic was to • Determine current knowledge gaps in heart transplant pathology • Identify limitations of current pathology classification systems • Discuss next steps in addressing gaps and refining classification system.

Human leukocyte antigen class I antibody-activated endothelium promotes CD206+ M2 macrophage polarization and MMP9 secretion through TLR4 signaling and P-selectin in a model of antibody-mediated rejection and allograft vasculopathy

HLA donor-specific antibodies (DSA) elicit alloimmune responses against the graft vasculature, leading to endothelial cell (EC) activation and monocyte infiltration during antibody-mediated rejection (AMR). AMR promotes chronic inflammation and remodeling, leading to thickening of the arterial intima termed transplant vasculopathy or cardiac allograft vasculopathy (CAV) in heart transplants. Intragraft-recipient macrophages serve as a diagnostic marker in AMR; however, their polarization and function remain unclear. In this study, we utilized an in vitro Transwell coculture system to explore the mechanisms of monocyte-to-macrophage polarization induced by HLA I DSA-activated ECs. Anti-HLA I (IgG or F(ab')2) antibody-activated ECs induced the polarization of M2 macrophages with increased CD206 expression and MMP9 secretion. However, inhibition of TLR4 signaling or PSGL-1-P-selectin interactions significantly decreased both CD206 and MMP9. Monocyte adherence to Fc-P-selectin coated plates induced M2 macrophages with increased CD206 and MMP9. Moreover, Fc-receptor and IgG interactions synergistically enhanced active-MMP9 in conjunction with P-selectin. Transcriptomic analysis of arteries from DSA+CAV+ rejected cardiac allografts and multiplex-immunofluorescent staining illustrated the expression of CD68+CD206+CD163+MMP9+ M2 macrophages within the neointima of CAV-affected lesions. These findings reveal a novel mechanism linking HLA I antibody-activated endothelium to the generation of M2 macrophages which secrete vascular remodeling proteins contributing to AMR and CAV pathogenesis.

Long-term post-transplantation outcomes in patients with hypertrophic cardiomyopathy: Single-center 35-year experience

BACKGROUND

Heart transplantation (HT) is the only option for most patients with end-stage heart failure and hypertrophic cardiomyopathy (HCM) who fail medical therapy. Data on the long-term outcomes post-transplant in HCM individuals remain scarce.

METHODS

We analyzed data of 319 adult patients who underwent HT between 1984 and 2019. Patients were followed for cardiac allograft rejection, cardiac allograft vasculopathy (CAV), death, or re-transplantation.

RESULTS

Outcomes of 24 patients with HCM, 160 with ischemic, and 135 with dilated cardiomyopathy were compared. During a mean follow-up of 11.6 ± 7.2 (max 27.8), 16.7 ± 8.2 (max 32.7), and 16.1 ± 9.7 (max 34.6) years after HT in hypertrophic, ischemic, and dilated cardiomyopathy groups, respectively: 10-year survival rate was 67%, 62%, 69%, respectively (p = .04). Post-transplantation, HCM individuals more often than the other two studied groups required prolonged inotropic support (37%, 12%, 17%, respectively, p = .02), temporary mechanical circulatory support (45%, 13%, 14%, respectively, p < .01), and renal replacement therapy immediately post-HT (55%, 19%, 24%, respectively, p < .01). No significant inter-group differences were noted in the 10-year freedom from acute allograft rejection (38%, 46%, 43%, respectively, p = .38) or 10-year freedom from CAV (88%, 78%, 81%, respectively, p = .57).

CONCLUSIONS

The long-term post-transplant prognosis of adult patients with hypertrophic cardiomyopathy is favorable despite more challenging immediate post-HT course.

Outcomes of untreated subclinical antibody-mediated rejection after heart transplantation

Subclinical antibody-mediated rejection (AMR) is represented by histopathological and/or immunopathological manifestations in the absence of significant cardiac allograft dysfunction. Treatment remains uncertain as there is a lack of data on asymptomatic heart transplant (HT) recipients (HTR) with a positive cardiac biopsy. We sought to determine the impact of untreated subclinical biopsy-proven AMR, regardless of circulating donor-specific antigen (DSA) expression, when diagnosed on surveillance biopsies in the first year after HT. This retrospective case control study evaluated 260 HTR between May 2004 and February 2021. These comprised 231 controls and 29 patients with untreated subclinical AMR. The mortality event rate was higher in controls (2.63 events per 100 person-years) compared to the scAMR Group (1.71 events per 100 person-years), a difference that did not reach statistical significance (hazard ratio 0.66, CI: 0.18-2.36). The combined event rate of cardiac allograft vasculopathy (CAV), graft dysfunction, or mortality was higher in the subclinical AMR group (5.60 events per 100 person-years) than in controls (3.89 events per 100 person-years) but did not reach statistical significance (hazard ratio 1.63, CI: 0.07-40.09). Our results suggest that subclinical AMR diagnosed in the first year after HT on surveillance biopsy is not associated with decreased survival. This may sway the management of subclinical AMR towards a more conservative approach in transplant-capable institutions that currently prioritize treatment, though prospective, randomized studies of such a management strategy are required.

Perioperative Management of Heart Transplantation: A Clinical Review

In this clinical review, the authors summarize the perioperative management of heart transplant patients with a focus on hemodynamics, immunosuppressive strategies, hemostasis and hemorrage, and the prevention and treatment of infectious complications.

European multicenter study on the real-world use and clinical impact of extracorporeal photopheresis after heart transplantation

BACKGROUND

Aim of this study was to describe the real-world use of extracorporeal photopheresis (ECP) and assess its impact on clinical outcomes in the modern era of heart transplantation.

METHODS

Seven transplant centers from 5 European countries participated in this retrospective, observational, single-arm chart review study. All patients received ECP after heart transplantation in 2015 or later. Data were extracted from medical records between November 2020 and December 2021.

RESULTS

Overall, 105 patients were enrolled and followed for an average of 2 years after initiation of ECP. Reasons to start ECP were acute cellular rejection (35.2%), rejection prevention (32.4%), mixed rejection (18.1%), and antibody-mediated rejection (14.3%). Rejection ISHLT grades improved from start to end of ECP treatment in 92% of patients treated with ECP for rejection. Of patients who started ECP to prevent rejection, 88% remained free from any rejection despite a reduction of calcineurin inhibitors. Overall survival was 95%, and no deaths were related to ECP. Safety events occurred in 18 patients, of which 13 experienced complications with venous access.

CONCLUSIONS

This study, the largest European ECP study in heart transplantation, demonstrates that ECP can effectively be used to treat different rejection types and to prevent rejection in the modern era of immunosuppression. Patients with rejections who have received ECP have shown high response as measured by histological improvements in ISHLT classification. A high percentage of patients in the prevention group remained free from rejection despite reduction in immunosuppression, in particular calcineurin inhibitors.

Human cytomegalovirus and Epstein-Barr virus infections occurring early after transplantation are risk factors for antibody-mediated rejection in heart transplant recipients

Background

Antibody-mediated rejection (AMR) is a serious complication affecting the survival of patients receiving transplantation. Human cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are common viral infections that occur after transplantation, frequently emerging as viral reactivation in donor grafts or transplant recipients. The present study aimed to investigate the association between CMV and EBV infections and early-onset AMR.

Materials and methods

This study was conducted at the Heart Transplantation Center of Padova General Hospital and included a cohort of 47 heart transplant recipients (HTxs), including 24 HTxs diagnosed with AMR and 23 control HTxs with no episodes of AMR. Only early cases of CMV and/or EBV infections (1-90 days after transplantation) were considered. Fisher's exact test and logistic regression analysis were used to statistically analyze the correlation and association between AMR and CMV or EBV infection.

Results

We observed a positive statistical association between CMV and EBV infections (two-sided Fisher's exact test, p = 0.0136) and between EBV infection and AMR (two-sided Fisher's exact test, p = 0.0034). Logistic regression analysis revealed a direct statistical association between CMV and EBV infections and AMR risk (p = 0.037 and 0.006 and odds ratio = 1.72 and 2.19, respectively). AMR occurrence was associated with increased viral loads of both CMV and EBV early after transplantation.

Discussion

These findings suggest the role of CMV and EBV infections as relevant risk factors for AMR in HTxs for the first time.

An Analysis of 183 Heart Transplants for Pediatric or Congenital Heart Disease-Impact of High Panel Reactive Antibody

BACKGROUND

We reviewed our management strategy and outcome data for all 179 patients with pediatric and/or congenital heart disease who underwent 183 heart transplants from January 1, 2011, to December 31, 2021, and evaluated the impact of elevated panel reactive antibody (PRA).

METHODS

High PRA was defined as PRA >10%. Univariate associations with long-term survival were assessed with Cox proportional hazards models. Impact of high PRA on survival was estimated with multivariable models.

RESULTS

PRA >10% was present in 60 of 183 transplants (32.8%), who were more likely to have prior cardiac surgery, higher number of prior cardiac operations, prior sternotomy, prior heart transplant, and positive crossmatch (24 of 60 [40.0%] vs 11 of 123 [8.9%], P < .0001). Univariate associations with long-term survival include acquired heart disease vs congenital or retransplant (hazard ratio [HR], 0.18; 95% CI, 0.053-0.593; P = .005), prior cardiac surgery (HR, 5.6; 95% CI, 1.32-23.75; P = .020), number of prior cardiac operations (HR, 1.3 for each additional surgery; 95% CI, 1.12-1.50; P = .0004), single ventricle (HR, 2.4; 95% CI, 1.05-5.48; P = .038), and preoperative renal dysfunction (HR, 3.4; 95% CI, 1.43-7.49; P = .002). In multivariate analysis, high PRA does not impact survival when controlling for each of the factors shown in univariable analysis to be associated with long-term survival. The Kaplan-Meier method provided the following survival estimates at 1 year (95% CI) and 5 years (95% CI) after cardiac transplantation: All patients, 93.6% (89.9%-97.3%) and 85.8% (80.0%-92.1%); PRA <10%, 96.6% (93.4%-99.9%) and 86.7% (79.6%-94.3%); and PRA >10%, 86.7% (78.0%-96.4%) and 83.8% (74.0%-95.0%). Despite high PRA being associated with higher mortality at 1 year (14.9% vs 3.8%, P = .035), no significant difference exists in Kaplan-Meier overall survival at 5 years posttransplant in patients with and without high PRA (log-rank P = .4).

CONCLUSIONS

In our cohort, 5-year survival in patients with high PRA (PRA >10%) is similar to that in patients without high PRA (PRA <10%), despite the presence of more risk factors in those with high PRA. Individualized immunomodulatory strategies can potentially mitigate the risk of high PRA.

Donor specific antibodies association with survival and adverse events after heart transplantation: A single center retrospective study between 2006 and 2021

OBJECTIVE

Newly detected donor HLA-specific antibodies (DSA) are historically known to be associated with reduced survival in heart transplant patients. Our objective is to clarify the modern incidence of DSA and determine its relationship with survival and MACE.

METHODS

This retrospective study included all patients undergoing orthotopic heart transplantation at Harefield Hospital, London between January 1, 2006 and May 31, 2021. We identified patients who developed DSA at any point post heart transplantation and its effect on survival and MACE (defined as rejection, coronary event, stroke, and arrhythmia.

RESULTS

In total of 232 patients were included with a median follow up time of 4.7 years post heart transplantation. 23.7% of patients included developed DSA post heart transplantation. There was a significantly increased risk of death in patients developing DSA versus not (sub distribution hazard ratio [SHR] 1.83, 95% confidence interval 1.03-3.24, p = .04). At the time of detection of DSA, 38.2% of the cohort had rejection necessitating treatment. A MACE event had occurred in 48.1% by 2 years and 53.7% by 3 years in the DSA cohort. There was a significantly increased risk of MACE in patients developing DSA versus not (SHR 2.48 [1.58-3.89, p < .0001]).

CONCLUSIONS

This study showed an increased risk of death and MACE in patients developing DSA post heart transplantation. Further research is required into the optimal management of these patients.

Severe cardiotoxicity in 2 patients with thymoma receiving immune checkpoint inhibitor therapy: A case report

RATIONALE

Immune checkpoint inhibitors (ICIs) are currently approved for a variety of cancers and their use is expanding from advanced disease to first-line metastatic and adjuvant therapies. With the wide application of immunotherapy, its adverse reactions are also the object we need to pay attention to. Among its adverse events, immune myocarditis has low morbidity, but a high fatality rate. Simultaneously, the unique biological properties of thymic epithelial tumors (TETs) increase the risk of immune-mediated toxicity.

PATIENT CONCERNS

Patient 1 underwent chest computed tomography (CT) in April 2019 due to physical examination, which showed pleural metastasis of thymoma. Tissue puncture under CT guidance revealed type B2 thymoma. First-line chemotherapy with docetaxel combined with nedaplatin was administered, and apatinib was administered as a maintenance therapy after chemotherapy. After a regular review, progression of the disease was observed in April 12, 2021.Patient 2 underwent anterior mediastinal tumor resection on August 2, 2019, due to the completion of the CT examination during myasthenia gravis to suggest a thymic tumor. Postoperative pathology revealed type B3 thymoma. The patient underwent local radiotherapy from October 2019 to November 2019. After irregular reexamination, the patient's condition was stable. Disease progression has been observed in June 2021.

DIAGNOSIS

Both patients were diagnosed with thymoma.

INTERVENTIONS

Patient 1 was administered one cycle of gemcitabine, carboplatin, and sintilimab after disease progression. Patient 2 was treated with docetaxel and cisplatin for 2 cycles, and tislelizumab was added in the second cycle.

OUTCOMES

Both patient 1 and patient 2 developed immune myocarditis after one cycle of immunotherapy. The difference was that patient 1 died within a few days. After a few days of active treatment for patient 2, the immune myocarditis did not improve significantly, and the patient chose to give up the treatment and go home. The shocking outcome is that the patient remains alive and stable.

LESSONS

Oncologists should be wary of ICI-related myocarditis owing to its early onset, nonspecific symptoms, and fulminant progression, especially when ICIs are used in combination. The patient's cardiac condition should be assessed before administering ICIs.

Long-term outcomes after heart transplantation using ex vivo allograft perfusion in standard risk donors: A single-center experience

INTRODUCTION

The Organ Care System (OCS) is an ex vivo perfusion platform for donor heart preservation. Short/mid-term post-transplant outcomes after its use are comparable to standard cold storage (CS). We evaluated long-term outcomes following its use.

METHODS

Between 2011 and 2013, 38 patients from a single center were randomized as a part of the PROCEED II trial to receive allografts preserved with CS (n = 19) or OCS (n = 19). Endpoints included 8-year survival, survival free from graft-related deaths, freedom from cardiac allograft vasculopathy (CAV), non-fatal major adverse cardiac events (NF-MACE), and rejections.

RESULTS

Eight-year survival was 57.9% in the OCS group and 73.7% in the CS group (p = .24). Freedom from CAV was 89.5% in the OCS group and 67.8% in the CS group (p = .13). Freedom from NF-MACE was 89.5% in the OCS group and 67.5% in the CS group (p = .14). Eight-year survival free from graft-related death was equivalent between the two groups (84.2% vs. 84.2%, p = .93). No differences in rejection episodes were observed (all p > .5).

CONCLUSIONS

In select patients receiving OCS preserved allografts, late post-transplant survival trended lower than those transplanted with an allograft preserved with CS. This is based on a small single-center series, and larger numbers are needed to confirm these findings.

Estimating filling pressures in paediatric heart transplant recipients using echocardiographic parameters and B-type natriuretic peptide

BACKGROUND

Longitudinal evaluation of allograft diastolic function in paediatric heart transplant recipients is important for early detection of acute rejection, cardiac allograft vasculopathy, and graft dysfunction. Mean diastolic right atrial and pulmonary capillary wedge pressures obtained at catheterisation are the reference standards for assessment. Echocardiography is non-invasive and more suitable for serial surveillance, but individual parameters have lacked accuracy. This study aimed to identify covariates of post-transplant mean right atrial and pulmonary capillary wedge pressures, including B-type natriuretic peptide and certain echocardiographic parameters.

METHODS

A retrospective review of 143 scheduled cardiac catheterisations and echocardiograms from 56 paediatric recipients transplanted from 2007 to 2011 was performed. Samples with rejection were excluded. Univariate and multivariate linear regression models using backward selection were applied to a database consisting of B-type natriuretic peptide, haemodynamic, and echocardiographic data.

RESULTS

Ln B-type natriuretic peptide, heart rate z-score, left ventricular end-diastolic dimension z-score, mitral E/e', and percent interventricular septal thickening in systole were independently associated with mean right atrial pressure. Ln B-type natriuretic peptide, heart rate z-score, left ventricular end-diastolic dimension z-score, left ventricular mass (observed/predicted), and mitral E/e' were independently associated with mean pulmonary capillary wedge pressure. Covariates of B-type natriuretic peptide included mean pulmonary artery and pulmonary capillary wedge pressures, height, haemoglobin, fractional shortening, percent interventricular septal thickening in systole, and pulmonary vascular resistance index.

CONCLUSIONS

B-type natriuretic peptide and echocardiographic indices of diastolic function were independently related to post-transplant mean right atrial and pulmonary capillary wedge pressures in paediatric heart transplant recipients without rejection.

Assessment and management of transplant renal artery stenosis. A literature review

BACKGROUND

transplant renal artery stenosis (TRAS) following kidney transplantation is a possible cause of graft failure. This review aimed to summarize the evidence about physiopathology, diagnosis and early and late effectiveness of the endovascular treatment (EVT), including angioplasty and stenting procedures.

METHODS

a literature research was performed using Pubmed, Scopus and the Cochrane Library databases (January 2000 to September 2020) according to PRISMA guidelines. Studies were included if they describe EVT, percutaneous transluminal angioplasty or stent placement of TRAS, published in English and with a minimum of ten patients.

RESULTS

56 studies were included. TRAS incidence ranges from 1% up to 12% in transplanted kidneys. The TRAS risk factors were: elderly donor and recipient, cytomegalovirus match status, Class II Donor Specific Antibodies (DSA), expanded donor criteria, delayed graft functioning and other anatomical and technical factors. The highest frequency of TRAS presentation is after 3-6 months after kidney transplantation. The most frequent localization of stenosis was para-anastomotic (ranging from 25% to 78%). In 9 studies, all patients were treated by percutaneous transluminal angioplasty (PTA), in 16 studies all patients received percutaneous transluminal stenting (PTS) and in 21 series patients received either PTA or PTS. The Twelve months patency rates after EVT ranged from 72% to 94%. The overall complication rate was 9%, with pseudoaneurysms and hematomas as most frequent complications.

CONCLUSION

TRAS can be successfully and safely treated through an endovascular approach. Stent delivery seems to guarantee a higher patency rate compared to simple angioplasty, however further studies are needed to confirm these results.

Immunotherapy-Related Cardiotoxicity Re-Emergence in Non-Small Cell Lung Cancer - A Case Report

PD-1/PD-L1 inhibitors activate immunological response and have become one of the main modalities of cancer treatment. However, they may result in the immune-related adverse events (irAEs). Immune-related cardiotoxicity is relatively rare but may become fatal. We will present a case of a male patient who experienced immunotherapy-related cardiotoxicity one year after received pembrolizumab treatment. The patient had atypical symptom presentation initially, but his condition deteriorated worsened rapidly and he developed severe cardiac disease. The patient experienced significant relief after corticosteroid treatment. Unfortunately, he experienced a reoccurence of the severe adverse event when discontinuing the use of corticosteroids. Ultimately, larger doses and longer courses of corticosteroid treatment cured the heart damage. Fortunately, we observed that lesions were stable and maintained for a long time after cessation of using pembrolizumab for eight months.

Coronary Microcirculatory Dysfunction and Acute Cellular Rejection After Heart Transplantation

BACKGROUND

Acute cellular rejection is a major determinant of mortality and retransplantation after heart transplantation. We sought to evaluate the prognostic implications of coronary microcirculatory dysfunction assessed by index of microcirculatory resistance (IMR) for the risk of acute cellular rejection after 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. IMR is microcirculatory resistance under maximal hyperemia. By measuring hyperemic mean transit time using 3 injections (4 mL each) of room-temperature saline under maximal hyperemia, IMR was calculated as hyperemic distal coronary pressure×hyperemic mean transit time. The primary end point was biopsy-proven acute cellular rejection of grade ≥2R during 2 years of follow-up after transplantation and was compared by using multivariable Cox proportional hazards regression according to IMR. The incremental prognostic value of IMR, in addition to the model with clinical factors, was evaluated by comparison of C-index, net reclassification index, and integrated discrimination index.

RESULTS

The mean age of recipients was 51.2±13.1 years (81.2% male), and the cumulative incidence of acute cellular rejection was 19.0% at 2 years. Patients with acute cellular rejection had significantly higher IMR values at 1 month than those without acute cellular rejection (23.1±8.6 versus 16.8±11.1, P=0.002). IMR was significantly associated with the risk of acute cellular rejection (per 5-U increase: adjusted hazard ratio, 1.18 [95% CI, 1.04-1.34], P=0.011) and the optimal cutoff value of IMR to predict acute cellular rejection was 15. Patients with IMR≥15 showed significantly higher risk of acute cellular rejection than those with IMR<15 (34.4% versus 3.8%; adjusted hazard ratio, 15.3 [95% CI 3.6-65.7], P<0.001). Addition of IMR to clinical variables showed significantly higher discriminant and reclassification ability for risk of acute cellular rejection (C-index 0.87 versus 0.74, P<0.001; net reclassification index 1.05, P<0.001; integrated discrimination index 0.20, P<0.001).

CONCLUSIONS

Coronary microcirculatory dysfunction assessed by IMR measured early after heart transplantation showed significant association with the risk of acute cellular rejection. In addition to surveillance endomyocardial biopsy, early stratification using IMR could be a clinically useful tool to identify patients at higher risk of future acute cellular rejection after heart transplantation. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02798731.

Antithymocyte globulin induction therapy and myocardial complement deposition in pediatric heart transplantation

BACKGROUND

Antithymocyte globulin (ATG) consists of polyclonal antibodies directed primarily against human T lymphocytes but may contain antibodies with affinity for other tissues in the transplanted organ, resulting in complement (C4d) deposition. This phenomenon has been demonstrated in endomyocardial biopsies (EMBs) of adult cardiac transplants. We examined the relationship of induction immunosuppression with ATG and C4d deposition in EMB of pediatric cardiac transplants.

METHODS

Results of C4d immunohistochemistry were available from all EMB of patients transplanted at our center between June 2012 and April 2018 (n = 48) who received induction immunosuppression with either ATG (n = 20) or basiliximab (n = 28) as the standard of care.

RESULTS

C4d deposition in the first year post-heart transplant was more commonly seen among patients who received ATG induction (20% of EMBs in ATG group vs 1% of EMBs in basiliximab group; p < .0001). C4d deposition related to ATG was observed early post-transplant (50% ATG vs 0% basiliximab on first EMB; p < .0001 and 35% ATG vs 0% basiliximab on the second EMB; p = .0012). While this difference waned by the third EMB (5% ATG vs 0% basiliximab; p = .41), positive C4d staining persisted to the sixth EMB in the ATG group only (6%).

CONCLUSION

C4d deposition is common on EMB up to 1 year post-pediatric cardiac transplant following ATG induction. This high rate of positive C4d staining in the absence of histologic AMR after ATG induction therapy must be accounted for in making clinical decisions regarding cardiac allograft rejection diagnosis and treatment.

Eculizumab for Antibody-Mediated Rejection in Heart Transplantation: A Case-Control Study

Complement inhibition offers a novel treatment approach for antibody-mediated rejection (AMR). We examined patients with hemodynamic compromise AMR 2010-2020, comparing 8 patients supplemented with eculizumab to 10 patients without; administration was at the treating physician's discretion. There were no significant differences between groups though eculizumab patients had a non-significantly higher inotrope score (208.8 mcg/kg/min vs 2.6 mcg/kg/min; p = 0.22), more ECMO (62.5% vs 20%; p = 0.066), and worse 1-year survival (37.5% vs 60%; p = 0.63). The role of eculizumab is uncertain in AMR; multicenter collaborative studies are essential to better define its role. This article is protected by copyright. All rights reserved.

Myocarditis Induced by Immune Checkpoint Inhibitors: Mechanisms and Therapeutic Prospects

Under physiological conditions, immune checkpoint molecules downregulate the activation and effector function of myocardial antigen-reactive T cells through an immunosuppressive pathway, thus enabling myocardial T cells to maintain immune homeostasis under the action of central and peripheral tolerance mechanisms. The PD-1/PD-L1 signalling pathway is particularly important for limiting the ability of T cells to attack the heart. Immune checkpoint inhibitors (ICIs) specifically block this PD-1/PD-L1-mediated restriction of T cell activation and other immunosuppressive pathways by targeting immune checkpoints. In recent years, with the wide use of ICIs in cancer treatment, even though the incidence of immunomyocarditis is low, it has attracted increasing attention because of its complex clinical symptoms, rapid progression of disease and high mortality rates. The pathogenesis, genetic susceptibility factors and predictive biomarkers of immunomyocarditis still need to be understood, and multidisciplinary cooperation in the clinical treatment of this complication is necessary.

Impact of Sex in the Efficacy of Perioperative Desensitization Procedures in Heart Transplantation: A Retrospective Cohort Study

Background

Sensitized patients, i.e. recipients with preformed donor-specific HLA antibodies (pfDSA), are at high-risk of developing antibody-mediated rejections (AMR) and dying after heart transplantation (HTx). Perioperative desensitization procedures are associated with better outcomes but can cause sensitization, which may influence their efficacy.

Methods

In sensitized patients (pfDSA>1000 mean immunofluorescence (MFI) units), we assessed the effect of perioperative desensitization by comparing treated patients to a historical control cohort. Multivariable survival analyses were performed on the time to main outcome, a composite of death and biopsy-proven AMR with 5-year follow-up.

Results

The study included 68 patients: 31 control and 37 treated patients. There was no difference in preoperative variables between the two groups, including cumulative pfDSA [4026 (1788;8725) vs 4560 (3162;13392) MFI units, p=0.28]. The cause of sensitization was pregnancy in 24/68, 35.3%, transfusion in 61/68, 89.7%, and previous HTx in 4/68, 5.9% patients. Multivariable analysis yielded significant protective association between desensitization and events (adjusted (adj.) hazard ratio (HR)=0.44 (95% confidence interval (95CI)=0.25-0.79), p=0.006) and deleterious association between cumulative pfDSA and events [per 1000-MFI increase, adj.HR=1.028 (1.002-1.053), p=0.031]. There was a sex-difference in the efficacy of desensitization: in men (n=35), the benefit was significant [unadj.HR=0.33 (95CI=0.14-0.78); p=0.01], but not in women (n=33) [unadj.HR=0.52 (0.23-1.17), p=0.11]. In terms of the number of patients treated, in men, 2.1 of patients that were treated prevented 1 event, while in women, 3.1 required treatment to prevent 1 event.

Conclusion

Perioperative desensitization was associated with fewer AMR and deaths after HTx, and efficacy was more pronounced in men than women.

Novel biomarkers useful in surveillance of graft rejection after heart transplantation

Heart transplantation (HTx) is considered the gold-standard therapy for the treatment of advanced heart failure (HF). The long-term survival in HTx is hindered by graft failure which represents one of the major limitations of the long-term efficacy of HTx. Endomyocardial biopsy (EMB) and the evaluation of donor-specific antibodies (DSA) are currently considered the essential diagnostic tools for surveillance of graft rejection. Recently, new molecular biomarkers (including cell-free DeoxyriboNucleic Acid, exosomes, gene profiling microarray, nanostring, reverse transcriptase multiplex ligation-dependent probe amplification, proteomics and immune profiling by quantitative multiplex immunofluorescence) provide useful information on mechanisms of graft rejection. The ambitious role of a similar change of perspective is aimed at a better and longer graft preservation.

Heart rate kinetics during standard cardiopulmonary exercise testing in heart transplant recipients: a longitudinal study

AIMS

Heart transplantation (HTx) results in complete autonomic denervation of the donor heart, causing resting tachycardia and abnormal heart rate (HR) responses to exercise. We determined the time course of suggestive cardiac reinnervation post HTx and investigated its clinical significance.

METHODS AND RESULTS

Heart rate kinetics during standard cardiopulmonary exercise testing at 2.5-5 years after HTx was assessed in 58 patients. According to their HR increase 30 s after exercise onset, HTx recipients were classified as denervated (slow responders: <5 beats per minute [b.p.m.]) or potentially reinnervated (fast responders: ≥5 b.p.m.). Additionally, in 30 patients, longitudinal changes of maximal oxygen consumption and HR kinetics were assessed during the first 15 post-operative years. At 2.5-5 years post HTx, 38% of our study population was potentially reinnervated. Fast responders were significantly younger (41 ± 15 years) than slow responders (53 ± 13 years, P = 0.003) but did not differ with regard to donor age, immunosuppressive regime, cardiovascular risk factors, endomyocardial biopsy, or vasculopathy parameters. While HR reserve (56 ± 20 vs. 39 ± 15 b.p.m., P = 0.002) and HR recovery after 60 s (15 ± 11 vs. 5 ± 6 b.p.m., P < 0.001) were greater in fast responders, resting HR, peak HR of predicted, and peak oxygen consumption of predicted were comparable.

CONCLUSIONS

Signs of reinnervation occurred mainly in younger patients. Maximal oxygen consumption was independent of HR kinetics.

The Evolving Immunotherapy Landscape and the Epidemiology, Diagnosis, and Management of Cardiotoxicity: JACC: CardioOncology Primer

Immune checkpoint inhibitors (ICIs) are newer therapies being applied to an increasing number of patients with cancer. Data suggest that up to 36% of cancer patients may be eligible for immunotherapy and, in late 2019, there were more than 3,362 clinical trials initiated to evaluate the effectiveness of immunotherapy, either as single agents or in combination with other immunotherapy, targeted therapies, or traditional cytotoxic or radiation therapy. With the combination of both immune and non-immune treatment approaches, the complexity in making the diagnosis of cardiotoxicity related to an ICI will increase substantially. Here, we summarize the published data on the epidemiology, diagnosis, and management of cardiotoxicity of ICIs. This is a rapidly evolving field, and as our understanding continues to evolve, previously considered hypotheses may not prove to be entirely correct. Research and continued collaborations are urgently needed to provide evidence-based cardiovascular care for this rapidly expanding and vulnerable cohort of patients. (J Am Coll Cardiol CardioOnc 2021;3:35-47) © 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Case Report: Early Transplant Rejection of a Methanol-Intoxicated Donor Heart in a Young Female Patient. A Diagnostic Approach With CMR, Cardiac Biopsy, and Genetic Risk Assessment

This case report describes the contributions of multimodality imaging, cardiac biopsy, and genetic sequencing to the diagnosis and management of heart transplant rejection in a 23-year old patient with dilated cardiomyopathy.

Discordance between immunofluorescence and immunohistochemistry C4d staining and outcomes following heart transplantation

BACKGROUND

Capillary deposition of C4d is an important marker of antibody-mediated rejection (AMR) following heart transplantation (HT). There are two immunopathologic assay methods for detecting C4d: frozen-tissue immunofluorescence (IF) and paraffin immunohistochemistry (IHC). The clinical significance of discrepancy between the results of IF and IHC has not been understood.

METHODS AND RESULTS

We reviewed 2187 biopsies from 142 HT recipients who had biopsies with assessment of both IF and IHC staining. Among them, 103 (73%) patients had negative IF and IHC C4d staining (Negative Group) and 32 (23%) patients had positive IF but negative IHC staining (Discordant Group). At the time of positive biopsy, 6 (19%) Discordant patients had graft dysfunction, compared to 5 (5%) Negative patients (p = .022). Cumulative incidence of cellular rejection at 1 year was comparable (31% vs. 29%, p = .46); however, cumulative incidence of AMR was significantly higher in the Discordant group (21% vs. 4%, p = .004). Overall 1-year survival was comparable (90% vs. 96%, p = .24); however, freedom from heart failure (HF) was significantly lower in the Discordant group (70% vs. 96%, p < .001).

CONCLUSION

The Discordant group showed higher rates of graft dysfunction, AMR and HF admission than the Negative group.

Pediatric heart transplantation: how to manage problems affecting long-term outcomes?

Since the initial International Society of Heart Lung Transplantation registry was published in 1982, the number of pediatric heart transplantations has increased markedly, reaching a steady state of 500-550 transplantation annually and occupying up to 10% of total heart transplantations. Heart transplantation is considered an established therapeutic option for patients with end-stage heart disease. The long-term outcomes of pediatric heart transplantations were comparable to those of adults. Issues affecting long-term outcomes include acute cellular rejection, antibody-mediated rejection, cardiac allograft vasculopathy, infection, prolonged renal dysfunction, and malignancies such as posttransplant lymphoproliferative disorder. This article focuses on medical issues before pediatric heart transplantation, according to the Korean Network of Organ Sharing registry and as well as major problems such as graft rejection and cardiac allograft vasculopathy. To reduce graft failure rate and improve long-term outcomes, meticulous monitoring for rejection and medication compliance are also important, especially in adolescents.

A Changing Paradigm in Heart Transplantation: An Integrative Approach for Invasive and Non-Invasive Allograft Rejection Monitoring

Cardiac allograft rejection following heart transplantation is challenging to diagnose. Tissue biopsies are the gold standard in monitoring the different types of rejection. The last decade has seen an increased emphasis on identifying non-invasive methods to improve rejection diagnosis and overcome tissue biopsy invasiveness. Liquid biopsy, as an efficient non-invasive diagnostic and prognostic oncological monitoring tool, seems to be applicable in heart transplant follow-ups. Moreover, molecular techniques applied on blood can be translated to tissue samples to provide novel perspectives on tissue and reveal new diagnostic and prognostic biomarkers. This review aims to provide a comprehensive overview of the state-of-the-art of the new methodologies in cardiac allograft rejection monitoring and investigate the future perspectives on invasive and non-invasive rejection biomarkers identification. We reviewed literature from the most used scientific databases, such as PubMed, Google Scholar, and Scopus. We extracted 192 papers and, after a selection and exclusion process, we included in the review 81 papers. The described limitations notwithstanding, this review show how molecular biology techniques and omics science could be deployed complementarily to the histopathological rejection diagnosis on tissue biopsies, thus representing an integrated approach for heart transplant patients monitoring.

Noninvasive biomarkers for prediction and diagnosis of heart transplantation rejection

For most patients with end-stage heart failure, heart transplantation is the treatment of choice. Allograft rejection is one of the major post-transplantation complications affecting graft outcome and survival. Recent advancements in science and technology offer an opportunity to integrate genomic and other omics-based biomarkers into clinical practice, facilitating noninvasive evaluation of allograft for diagnostic and prognostic purposes. Omics, including gene expression profiling (GEP) of blood immune cell components and donor-derived cell-free DNA (dd-cfDNA) are of special interest to researchers. Several studies have investigated levels of dd-cfDNA and miroRNAs in blood as potential markers for early detection of allograft rejection. One of the achievements in the field of transcriptomics is AlloMap, GEP of peripheral blood mononuclear cells (PBMC), which can identify 11 differentially expressed genes and help with detection of moderate and severe acute cellular rejection in stable heart transplant recipients. In recent years, the utilization of GEP of PBMC for identifying differentially expressed genes to diagnose acute antibody-mediated rejection and cardiac allograft vasculopathy has yielded promising results. Advancements in the field of metabolomics and proteomics as well as their potential implications have been further discussed in this paper.

Antibody-medicated rejection after heart transplantation: diagnosis and clinical implications

PURPOSE OF REVIEW

The present article will review the diagnosis of antibody-mediated rejection in heart transplant recipients and further explore the clinical implications.

RECENT FINDINGS

Improved diagnostic techniques have led to increased recognition of antibody-mediated rejection and better understanding of the long-term consequences in heart transplant recipients. Endomyocardial biopsy remains the gold standard for the diagnosis of antibody-medicated ejection; however, several advances in molecular testing have emerged, including the use of gene expression profiling, messenger RNA, and microRNA. Routine surveillance of donor-specific antibodies identifies recipients at high risk for graft compromise. Additionally, new monoclonal antibody therapies have broadened our repertoire in the treatment of rejection.

SUMMARY

Advances in molecular testing for antibody-mediated rejection may improve the associated long-term complication, while minimizing risk to the patient.

Canadian Cardiovascular Society/Canadian Cardiac Transplant Network Position Statement on Heart Transplantation: Patient Eligibility, Selection, and Post-Transplantation Care

Significant practice-changing developments have occurred in the care of heart transplantation candidates and recipients over the past decade. This Canadian Cardiovascular Society/Canadian Cardiac Transplant Network Position Statement provides evidence-based, expert panel recommendations with values and preferences, and practical tips on: (1) patient selection criteria; (2) selected patient populations; and (3) post transplantation surveillance. The recommendations were developed through systematic review of the literature and using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. The evolving areas of importance addressed include transplant recipient age, frailty assessment, pulmonary hypertension evaluation, cannabis use, combined heart and other solid organ transplantation, adult congenital heart disease, cardiac amyloidosis, high sensitization, and post-transplantation management of antibodies to human leukocyte antigen, rejection, cardiac allograft vasculopathy, and long-term noncardiac care. Attention is also given to Canadian-specific management strategies including the prioritization of highly sensitized transplant candidates (status 4S) and heart organ allocation algorithms. The focus topics in this position statement highlight the increased complexity of patients who undergo evaluation for heart transplantation as well as improved patient selection, and advances in post-transplantation management and surveillance that have led to better long-term outcomes for heart transplant recipients.

Circulating Donor Heart Exosome Profiling Enables Noninvasive Detection of Antibody-mediated Rejection

Background

Endomyocardial biopsy remains the gold standard for distinguishing types of immunologic injury-acute versus antibody-mediated rejection (AMR). Exosomes are tissue-specific extracellular microvesicles released by many cell types, including transplanted heart. Circulating transplant heart exosomes express donor-specific human leukocyte antigen (HLA) I molecules. As AMR is mediated by antibodies to donor HLAs, we proposed that complement deposition that occurs with AMR at tissue level would also occur on circulating donor heart exosomes.

Methods

Plasma exosomes in 4 patients were isolated by column chromatography and ultracentrifugation. Donor heart exosomes were purified using anti-donor HLA I antibody beads and complement C4d protein expression was assessed in this subset as marker for AMR.

Results

Three patients had no rejection episodes. Circulating donor heart exosomes showed troponin protein and mRNA expression at all follow-up time points. One patient developed AMR on day 14 endomyocardial biopsy that was treated with rituximab, IVIG/plasmapheresis. Time-specific detection of C4d protein was seen in donor heart exosome subset in this patient, which resolved with treatment. C4d was not seen in other 3 patients' donor exosomes.

Conclusions

Anti-donor HLA I specificity enables characterization of circulating donor heart exosomes in the clinical setting. Further characterization may open the window to noninvasively diagnose rejection type, such as AMR.

Outcomes of mechanical support for cardiogenic shock associated with late cardiac allograft failure

BACKGROUND

Late graft failure (LGF) is an unresolved issue after orthotopic heart transplant (OHT). In this study, we report characteristics and outcomes of severe LGF requiring mechanical circulatory support (MCS).

METHODS

All patients undergoing OHT from 2000 to 2018 at our center were reviewed. Patients re-admitted to the hospital for late graft failure (>3 months after initial discharge) and developing cardiogenic shock requiring MCS were identified. Outcomes and mortality were evaluated.

RESULTS

Twenty-six patients were identified. Median age was 37.3 years (interquartile range: 28.2-47.6) and 69% were male. Median time from initial transplant to MCS was 2.9 years. Etiology of graft failure was rejection in 19 patients (73%), transplant coronary artery disease (tCAD) in 3 (12%), with mixed tCAD or rejection in 4 (15%).

PD-1/PDL-1 Inhibitors and Cardiotoxicity; Molecular, Etiological and Management Outlines

Background

The US Food and Drug Administration (FDA) has approved several immunotherapeutic drugs for cancer since 2010, and many more are still being evaluated in other clinical studies. These inhibitors significantly increase response rates and result in the treatment of patients with advanced cancer. However, cancer immunotherapy leads to essential cardiac toxicity properties that have become distinct from other cancer patients' care and are mostly related to their etiology.

Aim of review

As potential implications, the occurrence of cardiovascular adverse events is particularly challenging and needs a comprehensive understanding of overall cancer-related etiology, clinical outcomes with different variable severity, and management.

Key scientific concepts of review

In terms of improving the overall survival of patients with cancer, clinicians should be careful in selecting either programmed cell death-1 (PD-1) or its programmed cell death ligand (PDL-1) inhibitors by evaluating their risk and clinical benefit for early intervention and decrease the level of morbidity and mortality of their patients. This review focuses on the effectiveness of PD-1/PL-1 antibodies and associated cardiotoxicity adverse events, including etiological mechanisms, diagnosis, and treatment.

Quadritherapy vs standard tritherapy immunosuppressant regimen after heart transplantation: A propensity score-matched cohort analysis

After heart transplant, adding everolimus (EVL) to standard immunosuppressive regimen mostly relies on converting calcineurin inhibitors (CNIs) into EVL. The aim of this study was to describe the effects of combining low-dose EVL and CNIs in maintenance immunosuppression regimen (quadritherapy) and compare it with standard tritherapy associating standard-dose CNIs, mycophenolate mofetil, and corticosteroids. In the 3-year registry cohort of heart transplanted patients, those who received quadritherapy were compared with those who received tritherapy. EVL was added after 3 months posttransplant. Three analyses were performed to control for confounders: propensity score matching, multivariable survival, and inverse probability score weighting analyses. Among 213 patients who were included (75 with quadritherapy), propensity score matching selected 64 unique pairs of patients with similar characteristics. In the matched cohort (n = 128), quadritherapy was associated with fewer deaths (3 [4.7%] vs 17 [21.9%], P = .007) and biopsy-proven acute rejections (15 [23.4%] vs 31 [48.4%], P = .002). These results were confirmed in the overall cohort (n = 213), after multivariable and inverse probability score weighting analyses. Renal function and donor-specific HLA-antibodies remained similar in both groups. Low-dose combination quadritherapy was associated with fewer deaths and rejections, compared with standard immunosuppression tritherapy.