Usefulness of routine surveillance endomyocardial biopsy 6 months after heart transplantation

Circulating long non-coding RNAs detection after heart transplantation and its accuracy in the diagnosis of acute cardiac rejection

Long non-coding RNAs (lncRNAs) are closely implicated in biological processes and diseases with high inflammatory components. These molecules exhibit significant temporal and tissue specificity. However, the expression and function of lncRNAs have not been studied in patients after heart transplantation. Thus, we aimed to identify circulating lncRNAs in these patients and evaluate their diagnostic capacity as potential biomarkers for the non-invasive detection of acute cellular rejection (ACR). For them, we performed a transcriptomic study based on ncRNA-seq technology to detect lncRNAs in serum samples, matched to routine endomyocardial biopsies, from patients without rejection episode (0R, n = 12) and with mild (1R, n = 16) or moderate-severe (≥ 2R, n = 12) ACR. We identified 11,062 circulating lncRNAs in the serum of patients after heart transplantation. Moreover, 6 lncRNAs showed statistically significant expression when the different ACR grades were compared. Among them, AC008105.3, AC006525.1, AC011455.8, AL359220.1, and AC025279.1 had relevant diagnostic capacity for detection of ≥ 2R (AUC of 0.850 to 1.000) and 1R (AUC of 0.750 to 0.854) grades, along with high specificity and positive predictive values (≥ 83%). In addition, AL359220.1 and AC025279.1 were independent predictors for the presence of moderate-severe ACR (odds ratio = 31.132, p < 0.01 and C statistic = 0.939, p < 0.0001; odds ratio = 18.693, p < 0.05 and C statistic = 0.902, p < 0.001; respectively). In conclusion, we describe, for the first time, circulating lncRNAs after heart transplantation as potential candidates for non-invasive detection of ACR. AL359220.1 and AC025279.1 showed excellent diagnostic capability correlating with the severity episode and were strong independent predictors of rejection.

Incidence of Acute Rejection Compared With Endomyocardial Biopsy Complications for Heart Transplant Patients in the Contemporary Era

BACKGROUND

The reference standard of detecting acute rejection (AR) in adult heart transplant (HTx) patients is an endomyocardial biopsy (EMB). The majority of EMBs are performed in asymptomatic patients. However, the incidence of treated AR compared with EMB complications has not been compared in the contemporary era (2010-current).

METHODS

The authors retrospectively analyzed 2769 EMBs obtained in 326 consecutive HTx patients between August 2019 and August 2022. Variables included surveillance versus for-cause indication, recipient and donor characteristics, EMB procedural data and pathological grades, treatment for AR, and clinical outcomes.

RESULTS

The overall EMB complications rate was 1.6%. EMBs performed within 1 mo after HTx compared with after 1 mo from HTx showed significantly increased complications (OR, 12.74, P  < 0.001). The treated AR rate was 14.2% in the for-cause EMBs and 1.2% in the surveillance EMBs. We found the incidence of AR versus EMB complications was significantly lower in the surveillance compared with the for-cause EMB group (OR, 0.05, P  < 0.001). We also found the incidence of EMB complications was higher than treated AR in surveillance EMBs.

CONCLUSIONS

The yield of surveillance EMBs has declined in the contemporary era, with a higher incidence of EMB complications compared with detected AR. The risk of EMB complications was highest within 1 mo after HTx. Surveillance EMB protocols in the contemporary era may need to be reevaluated.

Thoracic organ transplantation and pregnancy outcomes: systematic review and meta-analysis

PURPOSE

Pre-conceptual comorbidities, an inherent risk of graft loss, rejection during pregnancy, and the postpartum period in women with thoracic lung transplant may predispose them to increased risk of adverse feto-maternal outcomes. The study aimed to systematically analyze and assess the risk of adverse pregnancy outcomes in women with thoracic organ transplant.

METHODS

MEDLINE, EMBASE, and Cochrane library were searched for publication between January 1990 and June 2020. Risk of bias was assessed using Joanna Briggs critical appraisal tool for case series. The primary outcomes included maternal mortality and pregnancy loss. The secondary outcomes were maternal complications, neonatal complications, and adverse birth outcomes. The analysis was performed using the DerSimonian-Laird random effects model.

RESULTS

Eleven studies captured data from 275 parturient with thoracic organ transplant describing 400 pregnancies. The primary outcomes included maternal mortality {pooled incidence (95% confidence interval) 4.2 (2.5-7.1) at 1 year and 19.5 (15.3-24.5) during follow-up}. Pooled estimates yielded 10.1% (5.6-17.5) and 21.8% (10.9-38.8) risk of rejection and graft dysfunction during and after pregnancy, respectively. Although 67% (60.2-73.2) of pregnancies resulted in live birth, total pregnancy loss and neonatal death occurred in 33.5% (26.7-40.9) and 2.8% (1.4-5.6), respectively. Prematurity and low birth weight were reported in 45.1% (38.5-51.9) and 42.7% (32.8-53.2), respectively.

CONCLUSIONS

Despite pregnancies resulting in nearly 2/3rd of live births, high incidence of pregnancy loss, prematurity and low birth weight remain a cause of concern. Focused pre-conceptual counseling to avoid unplanned pregnancy, especially in women with transplant-related organ dysfunctions and complications, is vital to improve pregnancy outcomes.

PROSPERO NUMBER

CRD42020164020.

Survival of Heart Transplant Patients with Chagas' Disease Under Different Antiproliferative Immunosuppressive Regimens

Chagas' disease (CD) is an important cause of heart transplantation (HT). The main obstacle is Chagas' disease reactivation (CDR), usually associated to high doses of immunosuppressants. Previous studies have suggested an association of mycophenolate mofetil with increased CDR. However, mortality predictors are unknown. To identify mortality risk factors in heart transplant patients with CD and the impact of antiproliferative regimen on survival. Retrospective study with CD patients who underwent HT between January 2004 and September 2020, under immunosuppression protocol that prioritized azathioprine and change to mycophenolate mofetil in case of rejection. We performed univariate regression to identify mortality predictors; and compared survival, rejection and evidence of CDR between who received azathioprine, mycophenolate mofetil and those who changed from azathioprine to mycophenolate mofetil after discharge ("Change" group). A p-value < 0.05 was considered statistically significant. Eighty-five patients were included, 54.1% men, median age 49 (39-57) years, and 91.8% were given priority in waiting list. Nineteen (22.4%) used azathioprine, 37 (43.5%) mycophenolate mofetil and 29 (34.1%) switched therapy; survival was not different between groups, 2.9 (1.6-5.0) x 2.9 (1.8-4.8) x 4.2 (2.0-5.0) years, respectively; p=0.4. There was no difference in rejection (42%, 73% and 59% respectively; p=0.08) or in CDR (T. cruzi positive by endomyocardial biopsy 5% x 11% x 7%; p=0.7; benznidazole use 58% x 65% x 69%; p=0.8; positive PCR for T. cruzi 20% x 68% x 42% respectively; p=0.1) rates. This retrospective study did not show difference in survival in heart transplant patients with CD receiving different antiproliferative regimens. Mycophenolate mofetil was not associated with statistically higher rates of CDR or graft rejection in this cohort. New randomized clinical trials are necessary to address this issue.

Amplification of Plasma MicroRNAs for Non-invasive Early Detection of Acute Rejection after Heart Transplantation With Ultrasound-Targeted Microbubble Destruction

OBJECTIVE

Acute rejection (AR) screening has always been the focus of patient management in the first several years after heart transplantation (HT). As potential biomarkers for the non-invasive diagnosis of AR, microRNAs (miRNAs) are limited by their low abundance and complex origin. Ultrasound-targeted microbubble destruction (UTMD) technique could temporarily alter vascular permeability through cavitation. We hypothesized that increasing the permeability of myocardial vessels might enhance the abundance of circulating AR-related miRNAs, thus enabling the non-invasive monitoring of AR.

METHODS

The Evans blue assay was applied to determine efficient UTMD parameters. Blood biochemistry and echocardiographic indicators were used to ensure the safety of the UTMD. AR of the HT model was constructed using Brown-Norway and Lewis rats. Grafted hearts were sonicated with UTMD on postoperative day (POD) 3. The polymerase chain reaction was used to identify upregulated miRNA biomarkers in graft tissues and their relative amounts in the blood.

RESULTS

Amounts of six kinds of plasma miRNA, including miR-142-3p, miR-181a-5p, miR-326-3p, miR-182, miR-155-5p and miR-223-3p, were 10.89 ± 1.36, 13.54 ± 2.15, 9.84 ± 0.70, 8.55 ± 2.00, 12.50 ± 3.96 and 11.02 ± 3.47 times higher in the UTMD group than those in the control group on POD 3. Plasma miRNA abundance in the allograft group without UTMD did not differ from that in the isograft group on POD 3. After FK506 treatment, no miRNAs increased in the plasma after UTMD.

CONCLUSION

UTMD can promote the transfer of AR-related miRNAs from grafted heart tissue to the blood, allowing non-invasive early detection of AR.

Evaluation of the myocardial deformation in the diagnosis of rejection after heart transplantation

Introduction

Heart transplantation represents main therapy for end-stage heart failure. However, survival after transplantation is limited by development of graft rejection. Endomyocardial biopsy, an invasive and expensive procedure, is gold standard technique for diagnosis of rejection. Most of biopsy complications are observed using echocardiography. Novel echocardiographic techniques, such as myocardial strain and three-dimensional reconstruction, can be useful in heart transplant patients.

Purpose

To evaluate ventricular strain in heart transplant patients and association with rejection, cellular or humoral, as well as two- and three-dimensional echocardiographic parameters.

Methods

Cohort of patients from heart transplant program taken to echocardiography after endomyocardial biopsy, from December 2017 to January 2020. Ventricular strain and three-dimensional left ventricle parameters were studied. Rejection results were retrieved from medical record. Qualitative variables were expressed by absolute frequency and percentages, while continuous variables by means and standard deviations. Association between rejection and variables of interest was measured by odds ratio and confidence interval of 95%, with p-value < 0.05.

Results

123 post-endomyocardial biopsy echocardiographic exams were performed in 54 patients. Eighteen exams were excluded, lasting 105 exams to be evaluated for conventional and advanced echocardiographic parameters. Male patients were 60.4%. Prevalence of cellular rejection was 8.6%, humoral rejection 12.4%, and rejection of any type 20%. There was no association between right ventricular strain and rejection, whether cellular (p = 0.118 and p = 0.227 for septum and free wall, respectively), humoral (p = 0.845 and p = 0.283, respectively), or of any type (0.504 and 0.446). There was no correlation between rejection and left ventricle global longitudinal strain, three-dimensional ejection fraction or desynchrony index. Conventional parameters associated to rejection were left ventricle posterior wall thickness [OR 1.660 (1.163; 2.370), p = 0.005] and left ventricle mass index [OR 1.027 (1.011; 1.139), p = 0.001]. Left ventricle posterior wall thickness remained significant after analysis of cellular and humoral rejection separately [OR 1.825 (1.097; 3.036), p = 0.021 and OR 1.650 (1.028; 2.648), p = 0.038, respectively].

Conclusions

There was no association between ventricular strain, three-dimensional left ventricular ejection fraction and the desynchrony index and rejection, cellular or humoral. Evidence of association of graft rejection with left ventricle posterior wall thickness and left ventricle mass index was observed.

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.

Deep learning-enabled assessment of cardiac allograft rejection from endomyocardial biopsies

Endomyocardial biopsy (EMB) screening represents the standard of care for detecting allograft rejections after heart transplant. Manual interpretation of EMBs is affected by substantial interobserver and intraobserver variability, which often leads to inappropriate treatment with immunosuppressive drugs, unnecessary follow-up biopsies and poor transplant outcomes. Here we present a deep learning-based artificial intelligence (AI) system for automated assessment of gigapixel whole-slide images obtained from EMBs, which simultaneously addresses detection, subtyping and grading of allograft rejection. To assess model performance, we curated a large dataset from the United States, as well as independent test cohorts from Turkey and Switzerland, which includes large-scale variability across populations, sample preparations and slide scanning instrumentation. The model detects allograft rejection with an area under the receiver operating characteristic curve (AUC) of 0.962; assesses the cellular and antibody-mediated rejection type with AUCs of 0.958 and 0.874, respectively; detects Quilty B lesions, benign mimics of rejection, with an AUC of 0.939; and differentiates between low-grade and high-grade rejections with an AUC of 0.833. In a human reader study, the AI system showed non-inferior performance to conventional assessment and reduced interobserver variability and assessment time. This robust evaluation of cardiac allograft rejection paves the way for clinical trials to establish the efficacy of AI-assisted EMB assessment and its potential for improving heart transplant outcomes.

Diagnostic and Prognostic Value of a TDI-Derived Systolic Wall Motion Analysis as a Screening Modality for Allograft Rejection after Heart Transplantation

Background: Despite the risk for complications, allograft surveillance after orthotopic heart transplantation (OHT) is performed by cardiac catheterization and biopsies. We investigated the diagnostic and prognostic value of a TDI-derived systolic wall motion analysis of the posterobasal wall of the left ventricle (Sm) as a screening modality in OHT aftercare. Methods: We examined data of 210 eligible patients who underwent OHT between 2010 and 2020. Forty-four patients who had died within the initial hospital stay were excluded. For 166 patients, baseline and follow-up data were analyzed. The mean age at OHT was 46.2 (±11.4) years; 76.5% were male. Results: Within the observational period, 22 (13.3%) patients died. In total, 170 episodes of acute cellular or humoral rejections occurred (84 ISHLT1R; 13 ISHLT2R; 8 ISHLT3R; 65 AMR), and 29 catheterizations revealed cardiac allograft vasculopathy (5 CAV1; 4 CAV2; 20 CAV3). Individual Sm radial/longitudinal remained stable within the follow-up period (11.5 ± 2.2 cm/s; 10.9 ± 2.1 cm/s). Patients with acute rejections and CAV3 showed significant Sm radial/longitudinal reductions (AMR1: 1.6 ± 1.9 cm/s, confidence interval (CI) 0.77–0.243, p < 0.001; 1.8 ± 2.0 cm/s, CI 0.92–0.267, p < 0.001. ISHLT1R: 1.7 ± 1.8 cm/s, CI 1.32–2.08, p < 0.001; 2.0 ± 1.6 cm/s, CI 1.66–2.34, p < 0.001. CAV3: 1.3 ± 2.5 cm/s, CI 0.23–2.43, p < 0.017; 1.4 ± 2.8 cm/s, CI 0.21–2.66, p < 0.021). Lower Sm was associated with a threefold increase in all-cause mortality (hazard ratio (HR) 3.24, CI 1.2–8.76, p = 0.020; HR 2.92, CI 1.19–7.18, p = 0.019). Overall, Sm-triggered surveillance led to 0.75 invasive diagnostics per patient post-OHT year. Conclusions: Sm remained stable in the post-OHT course. Reductions indicated ISHLT1R, AMR1 and CAV3 and were associated with higher all-cause mortality. Sm-triggered surveillance may be referred to as a safe, high-yield screening modality in OHT aftercare.

Heart Failure Association of the ESC, Heart Failure Society of America and Japanese Heart Failure Society Position statement on endomyocardial biopsy

Endomyocardial biopsy (EMB) is an invasive procedure, globally most often used for the monitoring of heart transplant (HTx) rejection. In addition, EMB can have an important complementary role to the clinical assessment in establishing the diagnosis of diverse cardiac disorders, including myocarditis, cardiomyopathies, drug-related cardiotoxicity, amyloidosis, other infiltrative and storage disorders, and cardiac tumours. Improvements in EMB equipment and the development of new techniques for the analysis of EMB samples have significantly improved diagnostic precision of EMB. The present document is the result of the Trilateral Cooperation Project between the Heart Failure Association of the European Society of Cardiology, the Heart Failure Society of America, and the Japanese Heart Failure Society. It represents an expert consensus aiming to provide a comprehensive, up-to-date perspective on EMB, with a focus on the following main issues: (i) an overview of the practical approach to EMB, (ii) an update on indications for EMB, (iii) a revised plan for HTx rejection surveillance, (iv) the impact of multimodality imaging on EMB, and (v) the current clinical practice in the worldwide use of EMB.

Heart Failure Association, Heart Failure Society of America, and Japanese Heart Failure Society Position Statement on Endomyocardial Biopsy

Endomyocardial biopsy (EMB) is an invasive procedure, globally most often used for the monitoring of heart transplant rejection. In addition, EMB can have an important complementary role to the clinical assessment in establishing the diagnosis of diverse cardiac disorders, including myocarditis, cardiomyopathies, drug-related cardiotoxicity, amyloidosis, other infiltrative and storage disorders, and cardiac tumors. Improvements in EMB equipment and the development of new techniques for the analysis of EMB samples has significantly improved the diagnostic precision of EMB. The present document is the result of the Trilateral Cooperation Project between the Heart Failure Association of the European Society of Cardiology, Heart Failure Society of America, and the Japanese Heart Failure Society. It represents an expert consensus aiming to provide a comprehensive, up-to-date perspective on EMB, with a focus on the following main issues: (1) an overview of the practical approach to EMB, (2) an update on indications for EMB, (3) a revised plan for heart transplant rejection surveillance, (4) the impact of multimodality imaging on EMB, and (5) the current clinical practice in the worldwide use of EMB.

Protocol endomyocardial biopsy beyond 6 months-It is time to move on

The optimal duration and frequency of routine surveillance endomyocardial biopsy (EMB) have been questioned in the current era of heart transplantation (HT), where the advances in immunosuppression and donor selection strategies have led to a decline in acute allograft rejection. We investigated the utility of routine EMB beyond 6 months post-HT. A single-center retrospective review was performed on 2963 EMBs from 220 HT recipients over 10 years. Each EMB was categorized into protocol or symptom-triggered biopsy and reviewed for rejection. Heart transplant recipients with ≥2 known risk factors for rejection were designated as an elevated risk group. The majority of rejections occurred within 3 months following HT. The yield of routine protocol EMBs was significantly lower than symptom-triggered EMBs, not only during the first 6 months post-HT (1.6% vs. 33.3%, P < .0001), but more so during the 6-12 months (0.1% vs 83.0%, P < .0001). A similar pattern was observed in heart transplant recipients at both elevated and standard risk for rejection. In conclusion, EMB was found to be a low-yield screening modality for rejection beyond 6 months post-HT.

C-Reactive protein level and left ventricular mass are associated with acute cellular rejection after heart transplant

OBJECTIVES

Acute cellular rejection (ACR) remains a major complication of heart transplant (HT). The gold standard for its diagnosis is endomyocardial biopsy (EMB), whereas the role of non-invasive biomarkers for detecting ACR is unclear. This study aimed to identify non-invasive biomarkers for the diagnosis of ACR in patients undergoing HT and presenting with normal left ventricular function.

METHODS

We evaluated patients who underwent HT at a single center between January 2010 and June 2019. Patients were enrolled after HT, and those with left ventricular (LV) systolic dysfunction before EMB were excluded. We included only the results of the first EMB performed at least 30 days after HT (median, 90 days). Troponin, B-type natriuretic peptide (BNP), and C-reactive protein (CRP) levels were measured and echocardiography was performed up to 7 days before EMB. ACR was defined as International Society for Heart and Lung Transplantation grade 2R or 3R on EMB. We performed logistic regression analysis to identify the non-invasive predictors of ACR (2R or 3R) and evaluated the accuracy of each using area under the receiver operator characteristic curve analysis.

RESULTS

We analyzed 72 patients after HT (51.31±13.63 years; 25 [34.7%] women); of them, 9 (12.5%) developed ACR. Based on multivariate logistic regression analysis, we performed forward stepwise selection (entry criteria, p<0.05). The only independent predictors that remained in the model were CRP level and LV mass index. The optimal cut-off point for CRP level was ≥15.9 mg/L (odds ratio [OR], 11.7; p=0.007) and that for LV mass index was ≥111 g/m2 (OR, 13.6; p=0.003). The area under the receiver operating characteristic curve derived from this model was 0.87 (95% confidence interval [CI], 0.75-0.99), with sensitivity of 85.7% (95% CI, 42.1%-99.6%), specificity of 78.4% (95% CI, 64.7%-88.7%), positive predictive value of 35.3% (95% CI, 14.3%-61.7%), and negative predictive value of 97.6% (95% CI, 87.1%-99.9%).

CONCLUSIONS

Among patients undergoing HT, CRP level and LV mass were directly associated with ACR, but troponin and BNP levels were not.

Endomyocardial Biopsy and Prevalence of Acute Cellular Rejection in Heart Transplantation

BACKGROUND

Percutaneous endomyocardial biopsy (EMB) remains the criterion standard method for surveillance of allograft rejection after heart transplant (HT). However, data regarding utility of EMBs and prevalence of acute cellular rejection (ACR) in Asian populations are still limited. We aimed to report our experience in the use of EMBs and prevalence of ACR in HT recipients.

METHODS

We retrospectively evaluated all EMBs from consecutive HT recipients between January 2008 and December 2018. EMB pathology results were according to International Society for Heart and Lung Transplantation 2004 revision of biopsy grading. We also divided patients into previous era and current era group (underwent HT before and after 2015) to compare prevalence of ACR and survival outcome.

RESULTS

A total of 832 EMBs from 81 HT recipients were included. Pathologic reports revealed ACR grade 1R 22.8%, 2R 4.2%, and 3R 0.6%. At patient level, at least 1 episode of ACR grade 1R, 2R, and 3R were found in 70.6%, 24.7%, and 3.5% of the patients, respectively. When compared between era, frequency of EMB during the first year after HT in current era was significantly higher (9.74 ± 3.38 vs 4.93 ± 3.29, P < .001), but lower frequency of rejection grade ≥ 2R were found (2.3% vs 8.1%, P < .001). However, 1-year survival was not statistically different (76% in previous era vs 80% in current era, P = .37).

CONCLUSIONS

From our study, prevalence of grade ≥ 2R rejection was approximately 5%, which is comparable with previous studies. Further studies are needed to evaluate proper interval and number of EMBs in HT recipients.

Long-term surveillance biopsy: Is it necessary after pediatric heart transplant?

Due to limited and conflicting data in pediatric patients, long-term routine surveillance endomyocardial biopsy (RSB) in pediatric heart transplant (HT) remains controversial. We sought to characterize the rate of positive RSB and determine factors associated with RSB-detected rejection. Records of patients transplanted at a single institution from 1995 to 2015 with >2 year of post-HT biopsy data were reviewed for RSB-detected rejections occurring >2 year post-HT. We illustrated the trajectory of significant rejections (ISHLT Grade ≥3A/2R) among total RSB performed over time and used multivariable logistic regression to model the association between time and risk of rejection. We estimated Kaplan-Meier freedom from rejection rates by patient characteristics and used the log-rank test to assess differences in rejection probabilities. We identified the best-fitting Cox proportional hazards regression model. In 140 patients, 86% did not have any episodes of significant RSB-detected rejection >2 year post-HT. The overall empirical rate of RSB-detected rejection >2 year post-HT was 2.9/100 patient-years. The percentage of rejection among 815 RSB was 2.6% and remained stable over time. Years since transplant remained unassociated with rejection risk after adjusting for patient characteristics (OR = 0.98; 95% CI 0.78-1.23; P = 0.86). Older age at HT was the only factor that remained significantly associated with risk of RSB-detected rejection under multivariable Cox analysis (P = 0.008). Most pediatric patients did not have RSB-detected rejection beyond 2 years post-HT, and the majority of those who did were older at time of HT. Indiscriminate long-term RSB in pediatric heart transplant should be reconsidered given the low rate of detected rejection.

Impact of routine surveillance biopsy intensity on the diagnosis of moderate to severe cellular rejection and survival after pediatric heart transplantation

Data are lacking on RSB intensity and outcomes after pediatric heart transplantation. PHTS centers received a survey on RSB practices from 2005 to present. PHTS data were obtained for 2010-2013 and integrated with center-matched survey responses for analysis. Survey response rate was 82.6% (38/46). Centers were classified as low-, moderate-, and high-intensity programs based on RSB frequency (0-more than 8 RSB/y). RSB intensity decreased with increasing time from HT. Age at HT impacted RSB intensity mostly in year 1, with little to no impact in later years. Most centers have not replaced RSB with non-invasive methods, but many added ECHO and biomarker monitoring. Higher RSB intensity was not associated with decreased 4-year mortality (P=.63) or earlier detection of moderate to severe (ISHLT grade 2R/3R) cellular rejection (RSBMSR) in the first year (P=.87). First-year RSBMSR incidence did not differ with intensity or age at HT. Significant variability exists in RSB intensity, but with no impact on timing and incidence of RSBMSR or 4-year mortality. Reduction in RSB frequency may be safe in certain patients after pediatric HT.

Acute cellular rejection later than one year after heart transplantation: A single-center retrospective study at Skåne University Hospital in Lund 1988-2010

Routine endomyocardial biopsy (EMB) to detect acute cellular rejection (ACR) late (>1 year) after heart transplantation (HT) remains debated. To gain knowledge on late ACR and thereby approach this issue, we studied the incidence, predictors, and outcome of late ACR. 815 late EMBs from 183 patients transplanted 1988-2010 were retrospectively reviewed until June 30, 2012. Only 4.4% of the routine and 17.6% of the additional clinically indicated late EMBs showed ACR ≥ grade 2. With time post-HT, there was a clear trend toward fewer ACRs, a lower incidence of ACR per patient per year, and a deceleration in the decrease in the proportion of patients free from ACR. Sex-mismatching and first-year ACR were associated with an increased risk of late ACR, which also was associated with worse outcome. Although rare, when compared to our previous study on first-year EMBs, it appears as if late more often than early ACR remains undetected and that also late and not only early ACR influences outcome. Extended EMB surveillance >1 year post-HT therefore still seems reasonable in "high-risk" patients, as also suggested in the International Society for Heart and Lung Transplantation guidelines. These should include, but not be limited to, the two risk groups above.

Heart failure therapies: new strategies for old treatments and new treatments for old strategies

Heart failure, whether acute or chronic, remains a major health care crisis affecting almost 6 million Americans and over 23 million people worldwide. Roughly half of those affected will die within 5 years, and the annual cost exceeds $30 billion in the US alone. Although medical therapy has made some modest inroads in partially stemming the heart failure tsunami, there remains a significant population for whom medication is unsuccessful or has ceased being effective; such patients can benefit from heart transplantation or mechanical circulatory support. Indeed, in the past quarter century (and as covered in Cardiovascular Pathology over those years), significant improvements in pathologic understanding and in engineering design have materially enhanced the toolkit of options for such refractory patients. Mechanical devices, whether total artificial hearts or ventricular assist devices, have been reengineered to reduce complications and basic wear and tear. Transplant survival has also been extended through a better comprehension of and improved therapies for transplant vasculopathy and antibody-mediated rejection. Here we review the ideas and treatments from the last 25 years and highlight some of the new directions in nonpharmacologic heart failure therapy.

Surveillance Endomyocardial Biopsy in the Modern Era Produces Low Diagnostic Yield for Cardiac Allograft Rejection

BACKGROUND

The changing epidemiology of cardiac allograft rejection has prompted many to question the yield of surveillance endomyocardial biopsy (EMB) in heart transplantation (HT) patients. We sought to determine the yield of EMB in the modern era.

METHODS

We evaluated 2597 EMBs in 182 consecutive HT patients who survived to their first EMB. The EMBs were categorized as asymptomatic or clinically driven and were compared based on era of antiproliferative therapy use at our center (early azathioprine era: 1990-2000 vs modern mycophenolate era: 2000-2011).

RESULTS

In the modern era, patients had a higher prevalence of risk factors for developing rejection (≥ International Society of Heart and Lung Transplantation grade 2R); however, the frequency of rejection was decreased at all times (0-6 months: 60.2% vs 21.5%, P < 0.001, 6-12 months: 26.8% vs 1.8%, P < 0.001, 12-36 months: 32.3% vs 10.5%, P = 0.006). The yield of asymptomatic EMB decreased in the modern era between 0 and 6 months (10.9% vs 3.12%), 6 to 12 months (17% vs 0%), and years 2 to 3 (6.1% vs 1.5%). In the early era, the odds ratio of rejection during asymptomatic EMB compared to a clinically driven EMB was 0.47 (95% confidence interval, 0.31-0.71) and was decreased in the modern era (0.17 [0.07-0.42], P = 0.04). The probability of detecting rejection on asymptomatic EMB was significantly reduced in the modern era, even after adjustment for tacrolimus and induction therapy (1% vs 8%, P < 0.001).

CONCLUSIONS

The clinical yield of surveillance EMB has decreased in the modern era. The EMB in asymptomatic patients longer than 6 months after HT warrants further scrutiny.

Cost-Effectiveness of Routine Surveillance Endomyocardial Biopsy After 12 Months Post–Heart Transplantation

Background—

Despite low risk of late rejection after heart transplant (HT), surveillance endomyocardial biopsies (EMBs) are often continued for years. We assessed the cost-effectiveness of routine EMB after 12 months post-HT.

Methods and Results—

Markov model compared the following surveillance EMB strategies to baseline strategy of stopping EMB 12 months post-HT: (1) every 4 months during year 2 post-HT, (2) every 6 months during year 2, (3) every 4 months for years 2 to 3, and (4) every 6 months for years 2 to 3. Patients entered the model 12 months post-HT and were followed until 36 months. In all strategies, patients had EMB with symptoms; in biopsy strategies after 12 months, EMB was also performed as scheduled regardless of symptoms. One-way and Monte Carlo sensitivity analyses were performed. Stopping EMB at 12 months was dominant (more effective, less costly), saving $2884 per patient compared with the next best strategy (every 6 months for year 2) and gaining 0.0011 quality-adjusted life-years. Increasing the annual risk of asymptomatic rejection in years 2 to 3 from previously reported 2.5% to 8.5% resulted in the biopsy every 6 months for year 2 strategy gaining 0.0006 quality-adjusted life-years, but cost $4 913 599 per quality-adjusted life-year gained. EMB for 12 months was also no longer dominant when mortality risk from untreated asymptomatic rejection approached 11%; competing strategies still cost >$200 000 per quality-adjusted life-year as that risk approached 99%.

Conclusions—

Surveillance EMB for 12 months post-HT is more effective and less costly than EMB performed after 12 months, unless risks of asymptomatic cellular rejection and its mortality are strikingly higher than previously observed.

Donor-specific antibodies: can they predict C4d deposition in pediatric heart recipients?

There is limited evidence regarding the utility of circulating DSA in surveillance for AMR of pediatric heart recipients. Our hypothesis is that quantitation of DSA improves their power for predicting a C4d+, an integral component in the current diagnostic criteria of AMR. All pediatric recipients transplanted between 10/2005 and 1/2011 were retrospectively reviewed for DSA determined within 48 h of EMB. C4d+ was defined as >25% endothelial cell staining by immunohistochemical methods. A total of 183 paired DSA-EMB determinations were identified in 60 patients, a median of three paired studies per patient (range: 1-9). DSA were detected in 60 of these determinations. A receiver-operating characteristic plot identified a threshold single-antibody MFI of >6000 that strongly correlated with C4d+ (p < 0.0001) with a high negative predictive value (0.97) and specificity (0.95). The sensitivity and positive predictive values were 0.71 and 0.60, respectively. The predictive power of single-antigen DSA for C4d deposition was improved in pediatric heart recipients using an institution-specific MFI threshold value. In post-transplant care, quantitative DSA should be an essential component in the surveillance for AMR.