Recurrent acute cellular rejection graded ISHLT 1R early after heart transplantation negatively affects long-term outcomes: The prognostic significance of 1990 ISHLT grades 1B and 2

Cardiac magnetic resonance assessment of acute rejection and cardiac allograft vasculopathy in pediatric heart transplant

BACKGROUND

In pediatric heart transplant (PHT), cardiac catheterization with endomyocardial biopsy (EMB) is standard for diagnosing acute rejection (AR) and cardiac allograft vasculopathy (CAV) but is costly and invasive.

OBJECTIVES

To evaluate the ability of cardiac magnetic resonance (CMR) to noninvasively identify differences in PHT patients with AR and CAV.

METHODS

Patients were enrolled at three children's hospitals. Data were collected from surveillance EMB or EMB for-cause AR. Patients were excluded if they had concurrent diagnoses of AR and CAV, CMR obtained >7days from AR diagnosis, they had EMB negative AR, or could not undergo contrasted, unsedated CMR. Kruskal-Wallis test was used to compare groups: (1) No AR or CAV (Healthy), (2) AR, (3) CAV. Wilcoxon rank-sum test was used for pairwise comparisons.

RESULTS

Fifty-nine patients met inclusion criteria (median age 17years [IQR 15-19]) 10 (17%) with AR, and 11 (19%) with CAV. AR subjects had worse left ventricular ejection fraction compared to Healthy patients (p = 0.001). Global circumferential strain (GCS) was worse in AR (p = 0.054) and CAV (p = 0.019), compared to Healthy patients. ECV, native T1, and T2 z-scores were elevated in patients with AR.

CONCLUSIONS

CMR was able to identify differences between CAV and AR. CAV subjects had normal global function but abnormal GCS which may suggest subclinical dysfunction. AR patients have abnormal function and tissue characteristics consistent with edema (elevated ECV, native T1 and T2 z-scores). Characterization of CMR patterns is critical for the development of noninvasive biomarkers for PHT and may decrease dependence on EMB.

Use of intraoperative haemoadsorption in patients undergoing heart transplantation: a proof-of-concept randomized trial

AIMS

The aim of this trial was to compare the clinical effects of intraoperative haemoadsorption versus standard care in patients undergoing orthotopic heart transplantation (OHT).

METHODS AND RESULTS

In a randomized, controlled trial, OHT recipients were randomized to receive intraoperative haemoadsorption or standard care. Outcomes were vasoactive-inotropic score (VIS), frequency of vasoplegic syndrome (VS) in the first 24 h; post-operative change in procalcitonin (PCT) and C-reactive protein (CRP) levels; intraoperative change in mycophenolic acid (MPA) concentration; frequency of post-operative organ dysfunction, major complications, adverse immunological events and length of in-hospital stay and 1-year survival. Sixty patients were randomized (haemoadsorption group N = 30, control group N = 25 plus 5 exclusions). Patients in the haemoadsorption group had a lower median VIS and rate of VS (VIS: 27.2 [14.6-47.7] vs. 41.9 [22.4-63.2], P = 0.046, and VS: 20.0% vs. 48.0%, P = 0.028, respectively), a 6.4-fold decrease in the odds of early VS (OR: 0.156, CI: 0.029-0.830, P = 0.029), lower PCT levels, shorter median mechanical ventilation (MV: 25 [19-68.8] hours vs. 65 [23-287] hours, P = 0.025, respectively) and intensive care unit stay (ICU stay: 8.5 [8.0-10.3] days vs. 12 [8.5-18.0] days, P = 0.022, respectively) than patients in the control group. Patients in the haemoadsorption versus control group experienced lower rates of acute kidney injury (AKI: 36.7% vs. 76.0%, P = 0.004, respectively), renal replacement therapy (RRT: 0% vs. 16.0%, P = 0.037, respectively) and lower median per cent change in bilirubin level (PCB: 2.5 [-24.6 to 71.1] % vs. 72.1 [11.2-191.4] %, P = 0.009, respectively) during the post-operative period. MPA concentrations measured at pre-defined time points were comparable in the haemoadsorption compared to control groups (MPA pre-cardiopulmonary bypass: 2.4 [1.15-3.60] μg/mL vs. 1.6 [1.20-3.20] μg/mL, P = 0.780, and MPA 120 min after cardiopulmonary bypass start: 1.1 [0.58-2.32] μg/mL vs. 0.9 [0.45-2.10] μg/mL, P = 0.786). The rates of cardiac allograft rejection, 30-day mortality and 1-year survival were similar between the groups.

CONCLUSIONS

Intraoperative haemoadsorption was associated with better haemodynamic stability, mitigated PCT response, lower rates of post-operative AKI and RRT, more stable hepatic bilirubin excretion, and shorter durations of MV and ICU stay. Intraoperative haemoadsorption did not show any relevant adsorption effect on MPA. There was no increase in the frequency of early cardiac allograft rejection related to intraoperative haemoadsorption use.

Extracorporeal photopheresis in the treatment of cardiac allograft rejection: A single-centre experience

Despite novel immunosuppressive (IS) protocols, adverse effects of IS drugs continue to have notable negative impact on patient and cardiac allograft survival after heart transplantation (HTx). Therefore, IS regimens with less toxic side effects are sorely needed. We aimed to evaluate the efficacy of extracorporeal photopheresis (ECP) in combination with tacrolimus-based maintenance IS therapy in the treatment of allograft rejection in adult HTx recipients. Indications for ECP included acute moderate-to-severe or persistent mild cellular rejection, or mixed rejection. Twenty-two patients underwent a median of 22(2-44) ECP treatments after HTx. Median duration of ECP course was 173.5(2-466) days. No relevant adverse effects of ECP were noted. Reduction of methylprednisolone doses was safe throughout the ECP course. ECP, used in conjunction with pharmacological anti-rejection therapy, had a successful reversal of cardiac allograft rejection, decreased the rates of subsequential rejection episodes and normalized the allograft function in patients completing the ECP course. Short- and long-term survivals were excellent (91% at 1 and 5 years post-ECP) and comparable to International Society for Heart and Lung Transplantation registry data on HTx recipient overall survival. In conclusion, ECP can be safely used for the treatment and prevention of cardiac allograft rejection in conjunction with traditional IS regimen.

Clinical approach to acute cellular rejection from the pediatric heart transplant society

BACKGROUND

Early detection of cardiac allograft rejection is crucial for post-transplant graft survival. Despite the progress made in immunosuppression strategies, acute cellular rejection remains a serious complication during and after the first post-transplant year, and there is a continued lack of consensus regarding its treatment, especially in pediatric transplant patients.

METHODS

An open request was placed via the listserv to the membership of the Pediatric Heart Transplant Society (PHTS). Along with a broad literature search, numerous institutional protocols were pooled, analyzed and consolidated. A clinical approach document was generated highlighting areas of consensus and practice variation.

RESULTS

The clinical approach document divides cellular rejection by International Society for Heart and Lung Transplantation grades and provides management strategies for each, including persistent cellular rejection.

CONCLUSIONS

Cellular rejection treatment can be tailored to the clinical status, graft function, and the grade of cellular rejection. A case of mild and asymptomatic rejection may not require treatment, whereas a higher-grade rejection or rejection with graft dysfunction or hemodynamic compromise may require aggressive intravenous therapies, changes to maintenance immunosuppression therapy and augmented surveillance.

Cardiac magnetic resonance diastolic indices correlate with ventricular filling pressures in pediatric heart transplant recipients

BACKGROUND

Atrial and ventricular filling pressures are routinely used in pediatric heart transplant (PHTx) recipients to assess graft function. We hypothesized that cardiac magnetic resonance (CMR) diastolic indices correlate with filling pressures, providing a noninvasive method of hemodynamic assessment.

METHODS

Pediatric heart transplant recipients were prospectively enrolled at the time of cardiac catheterization. Pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP) were measured. CMR included standard volumetric analysis. Filling curves were calculated by contouring every phase in the short-axis stack. Global longitudinal and circumferential strain (GLS, GCS) were calculated using feature tracking. Atrial volumes and ejection fraction were calculated from 4-chamber and 2-chamber cine images. Correlations were analyzed using Spearman's Rho; modeling was performed with multivariable logistic regression.

RESULTS

A total of 35 patients with a mean age of 15.5 years were included, 12 with acute rejection. The median time post-transplant was 6.2 years. Peak filling rate (PFR) and peak LV ejection rate/end-diastolic volume (PER/EDV) correlated with PCWP (rho = 0.48 p = .005, and rho = -0.35 p = .046, respectively) as did GLS and GCS (rho = 0.52 p = .002, and 0.40 p = .01). Indexed maximum and minimum left atrial (LA) volume correlated with PCWP (rho = 0.41, p = .01, rho = 0.41 p = .01), and LA ejection fraction inversely correlated with PCWP (rho = -0.40, p = .02). GLS and GCS correlated with RAP (rho = 0.55, p = .001 and rho = 0.43, p = .01). A model including LV GLS and PFR estimated PCWP ≥12 mmHg with an area under the curve of 0.84.

CONCLUSIONS

Cardiac magnetic resonance can be a useful noninvasive modality to assess for signs of diastolic dysfunction after PHTx.

The Role of Left Atrial Longitudinal Strain in the Diagnosis of Acute Cellular Rejection in Heart Transplant Recipients

Our aim was to investigate the role of left atrial longitudinal strain (LALS) in the non-invasive diagnosis of acute cellular rejection (ACR) episodes in heart transplant (HTx) recipients. Methods: We performed successive echocardiographic exams in 18 consecutive adult HTx recipients in their first year after HTx within 3 h of the routine surveillance endomyocardial biopsies (EMB) in a single center. LALS parameters were analyzed with two different software. We investigated LALS association with ACR presence, as well as inter-vendor variability in comparable LALS values. Results: A total of 147 pairs of EMB and echo exams were carried out. Lower values of LALS were significantly associated with any grade of ACR presence. Peak atrial longitudinal strain (PALS) offered the best diagnostic value for any grade of ACR, with a C statistic of 0.77 using one software (95% CI 0.68−0.84, p < 0.0005) and 0.64 with the other (95% CI 0.54−0.73, p = 0.013) (p = 0.02 for comparison between both curves). Reproducibility between comparable LALS parameters was poor (intraclass correlation coefficients were 0.60 for PALS, 95% CI 0.42−0.73, p < 0.0005; and 0.42 for PALS rate, 95% CI −0.13−0.68, p < 0.0005). Conclusions: LALS variables might be a sensitive marker of ACR in HTx recipients, principally discriminating between those studies without rejection and those with any grade of ACR. Inter-vendor variability was significant.

Pre-transplant immune cell function assay as a predictor of early cardiac allograft rejection

INTRODUCTION

ImmuKnow, an immune cell function assay that quantifies overall immune system activity can assist in post-transplant immunosuppression adjustment. However, the utility of pre-transplant ImmuKnow results representing a patient's baseline immune system activity is unknown. This study sought to assess if pre-transplant ImmuKnow results are predictive of rejection at the time of first biopsy in our cardiac transplant population.

METHODS

This is a single center, retrospective observational study of consecutive patients from January 1, 2018 to October 1, 2020 who underwent orthotopic cardiac transplantation at NYU Langone Health. Patients were excluded if a pre-transplant ImmuKnow assay was not performed. ImmuKnow results were categorized according to clinical interpretation ranges (low, moderate, and high activity), and patients were divided into two groups: a low activity group versus a combined moderate-high activity group. Pre-transplant clinical characteristics, induction immunosuppression use, early postoperative tacrolimus levels, and first endomyocardial biopsy results were collected for all patients. Rates of clinically significant early rejection (defined as rejection ≥ 1R/1B) were compared between pre-transplant ImmuKnow groups.

RESULTS

Of 110 patients who underwent cardiac transplant, 81 had pre-transplant ImmuKnow results. The low ImmuKnow activity group was comprised of 15 patients, and 66 patients were in the combined moderate-high group. Baseline characteristics were similar between groups. Early rejection occurred in 0 (0%) patients with low pre-transplant ImmuKnow levels. Among the moderate- high pre-transplant ImmuKnow group, 16 (24.2%) patients experienced early rejection (P = .033). The mean ImmuKnow level in the non-rejection group was the 364.9 ng/ml of ATP compared to 499.3 ng/ml of ATP for those with rejection (P = .020).

CONCLUSION

Patients with low pre-transplant ImmuKnow levels had lower risk of early rejection when compared with patients with moderate or high levels. Our study suggests a possible utility in performing pre-transplant ImmuKnow to identify patients at-risk for early rejection who may benefit from intensified upfront immunosuppression as well as to recognize those where slower calcineurin inhibitor initiation may be appropriate.

Rejection surveillance in pediatric heart transplant recipients: Critical reflection on the role of frequent and long-term routine surveillance endomyocardial biopsies and comprehensive review of non-invasive rejection screening tools

BACKGROUND

Despite significant medical advances in the field of pediatric heart transplantation (HT), acute rejection remains an important cause of morbidity and mortality. Endomyocardial biopsy (EMB) remains the gold-standard method for diagnosing rejection but is an invasive, expensive, and stressful process. Given the potential adverse consequences of rejection, routine post-transplant rejection surveillance protocols incorporating EMB are widely employed to detect asymptomatic rejection. Each center employs their own specific routine rejection surveillance protocol, with no consensus on the optimal approach and with high inter-center variability. The utility of high-frequency and long-term routine surveillance biopsies (RSB) in pediatric HT has been called into question.

METHODS

Sources for this comprehensive review were primarily identified through searches in biomedical databases including MEDLINE and Embase.

RESULTS

The available literature suggests that the diagnostic yield of RSB is low beyond the first year post-HT and that a reduction in RSB intensity from high-frequency to low-frequency can be done safely with no impact on early and mid-term survival. Though there are emerging non-invasive methods of detecting asymptomatic rejection, the evidence is not yet strong enough for any test to replace EMB.

CONCLUSION

Overall, pediatric HT centers in North America should likely be doing fewer RSB than are currently performed. Risk factors for rejection should be considered when designing the optimal rejection surveillance strategy. Noninvasive testing including emerging biomarkers may have a complementary role to aid in safely reducing the need for RSB.

Steroid withdrawal after heart transplantation in adults

Corticosteroids (CSs) are a key component of immunosuppressive treatment after heart transplantation (HTx). While effectively preventing acute rejection, several adverse effects including diabetes, hypertension, osteoporosis, and hyperlipidemia are associated with long-term use. As these complications may impair long-term outcome in HTx recipients, withdrawal of CSs is highly desirable, however, no uniform approach exists. Previous experience suggests that CS withdrawal can be accomplished without an increase in the incidence of acute rejection and even carrying a survival benefit. Also, common complications related to long-term CS use appear to be less frequent following CS discontinuation. Recipients who successfully discontinue CSs, however, likely belong to an immune-privileged subset of patients with low risk of post-transplant complications. Available studies evaluating CS withdrawal are highly heterogeneous and consensus on optimal timing and eligibility for withdrawal is lacking. Efforts to improve the understanding of optimal CS withdrawal strategy are of great importance in order to safely promote CS weaning in eligible patients and thereby alleviate the adverse effects of long-term CS use on post-transplant outcomes. The purpose of this review was to evaluate different protocols of CS withdrawal after HTx in terms of clinical outcomes and to explore criteria for successful CS withdrawal.

Cell-free DNA donor fraction analysis in pediatric and adult heart transplant patients by multiplexed allele-specific quantitative PCR: Validation of a rapid and highly sensitive clinical test for stratification of rejection probability

Lifelong noninvasive rejection monitoring in heart transplant patients is a critical clinical need historically poorly met in adults and unavailable for children and infants. Cell-free DNA (cfDNA) donor-specific fraction (DF), a direct marker of selective donor organ injury, is a promising analytical target. Methodological differences in sample processing and DF determination profoundly affect quality and sensitivity of cfDNA analyses, requiring specialized optimization for low cfDNA levels typical of transplant patients. Using next-generation sequencing, we previously correlated elevated DF with acute cellular and antibody-mediated rejection (ACR and AMR) in pediatric and adult heart transplant patients. However, next-generation sequencing is limited by cost, TAT, and sensitivity, leading us to clinically validate a rapid, highly sensitive, quantitative genotyping test, myTAI_HEART^®, addressing these limitations. To assure pre-analytical quality and consider interrelated cfDNA measures, plasma preparation was optimized and total cfDNA (TCF) concentration, DNA fragmentation, and DF quantification were validated in parallel for integration into myTAI_HEART reporting. Analytical validations employed individual and reconstructed mixtures of human blood-derived genomic DNA (gDNA), cfDNA, and gDNA sheared to apoptotic length. Precision, linearity, and limits of blank/detection/quantification were established for TCF concentration, DNA fragmentation ratio, and DF determinations. For DF, multiplexed high-fidelity amplification followed by quantitative genotyping of 94 SNP targets was applied to 1168 samples to evaluate donor options in staged simulations, demonstrating DF call equivalency with/without donor genotype. Clinical validation studies using 158 matched endomyocardial biopsy-plasma pairs from 76 pediatric and adult heart transplant recipients selected a DF cutoff (0.32%) producing 100% NPV for ≥2R ACR. This supports the assay’s conservative intended use of stratifying low versus increased probability of ≥2R ACR. myTAI_HEART is clinically validated for heart transplant recipients ≥2 months old and ≥8 days post-transplant, expanding opportunity for noninvasive transplant rejection assessment to infants and children and to all recipients >1 week post-transplant.