Endomyocardial biopsy in heart transplantation: schedule or event?

Histopathological Characteristics of Percutaneous Endomyocardial Biopsy in Heart Transplant Rejection Surveillance: A Single Center Experience

BACKGROUND

Heart transplantation (HT) remains the ultimate treatment for end-stage heart failure. An endomyocardial biopsy (EMB) is "the gold standard" diagnostic procedure used in HT rejection surveillance. The aim of this study is to provide a detailed analysis of the histopathological characteristics of the EMB and to investigate if there is a correlation between some histopathological changes, such as fibrosis, vasculitis, Quilty effect (Q.E.), myocytes damage, and the presence of episodes of acute rejection.

METHODS

In this retrospective study, 200 EMBs were included, coming from 65 patients transplanted in the Emergency Institute for Cardiovascular Diseases and Transplantation (ICvDT) Targu Mures between 2012 and 2024. Fibrosis, vasculitis, Q.E., myocyte damage, etc., were microscopically evaluated to see if these parameters correlate with rejection episodes.

RESULTS

The mean age was 38.18 years (SD 15.67), 25% of biopsies being recorded in the 41-50 age group. 77.14% of total acute cellular rejection (ACR) was of mild rejection, with most registered in the 11-20 age group; the cases of severe rejection being recorded in the 41-50 age group. Antibody-mediated rejection (AMR) was recorded more frequently in women with a representation of 23.4%, compared to 8.5% of men. 86.7% (39 cases) of the total number of EMBs with fibrosis score 3 and 71.4% (15 cases) of the total EMBs with fibrosis score 2 were recorded in men, compared to the 28.6% (6 cases) of fibrosis score 2 recorded in women (p = 0.013). 50.0% of all the EMB recorded in the 61-70 age group showed fibrosis score 3, compared to 34.8% of those from the 21-30 age group. The Q.E. was identified in 13% of the biopsies and, in some patients, it was observed across 3-4 successive biopsies. Mild vasculitis was associated in 34.9% of cases with ISHLT ≥ 1R and moderate vasculitis was associated in 87.5% of cases with ISHLT ≥ 1R.

CONCLUSIONS

Fibrosis was detected much more frequently in men and in the 61-70 age group. In addition to the histopathological changes specific to acute rejection, there are other pathological changes, such as the Q.E., and vasculitis and myocytes damage and disarray, that seem to suggest a close connection with rejection, but extensive studies are needed to confirm this.

Biomarkers from subcutaneous engineered tissues predict acute rejection of organ allografts

Invasive graft biopsies assess the efficacy of immunosuppression through lagging indicators of transplant rejection. We report on a microporous scaffold implant as a minimally invasive immunological niche to assay rejection before graft injury. Adoptive transfer of T cells into Rag2-/- mice with mismatched allografts induced acute cellular allograft rejection (ACAR), with subsequent validation in wild-type animals. Following murine heart or skin transplantation, scaffold implants accumulate predominantly innate immune cells. The scaffold enables frequent biopsy, and gene expression analyses identified biomarkers of ACAR before clinical signs of graft injury. This gene signature distinguishes ACAR and immunodeficient respiratory infection before injury onset, indicating the specificity of the biomarkers to differentiate ACAR from other inflammatory insult. Overall, this implantable scaffold enables remote evaluation of the early risk of rejection, which could potentially be used to reduce the frequency of routine graft biopsy, reduce toxicities by personalizing immunosuppression, and prolong transplant life.

Native T1 mapping detects both acute clinical rejection and graft dysfunction in pediatric heart transplant patients

BACKGROUND

Cardiovascular magnetic resonance (CMR) is emerging as an important tool for cardiac allograft assessment. Native T1 mapping may add value in identifying rejection and in assessing graft dysfunction and myocardial fibrosis burden. We hypothesized that CMR native T1 values and features of textural analysis of T1 maps would identify acute rejection, and in a secondary analysis, correlate with markers of graft dysfunction, and with fibrosis percentage from endomyocardial biopsy (EMB).

METHODS

Fifty cases with simultaneous EMB, right heart catheterization, and 1.5 T CMR with breath-held T1 mapping via modified Look-Locker inversion recovery (MOLLI) in 8 short-axis slices and subsequent quantification of mean and peak native T1 values, were performed on 24 pediatric subjects. A single mid-ventricular slice was used for image texture analysis using nine gray-level co-occurrence matrix features. Digital quantification of Masson trichrome stained EMB samples established degree of fibrosis. Markers of graft dysfunction, including serum brain natriuretic peptide levels and hemodynamic measurements from echocardiography, catheterization, and CMR were collated. Subjects were divided into three groups based on degree of rejection: acute rejection requiring new therapy, mild rejection requiring increased ongoing therapy, and no rejection with no change in treatment. Statistical analysis included student's t-test and linear regression.

RESULTS

Peak and mean T1 values were significantly associated with acute rejection, with a monotonic trend observed with increased grade of rejection. Texture analysis demonstrated greater spatial heterogeneity in T1 values, as demonstrated by energy, entropy, and variance, in cases requiring treatment. Interestingly, 2 subjects who required increased therapy despite low grade EMB results had abnormal peak T1 values. Peak T1 values also correlated with increased BNP, right-sided filling pressures, and capillary wedge pressures. There was no difference in histopathological fibrosis percentage among the 3 groups; histopathological fibrosis did not correlate with T1 values or markers of graft dysfunction.

CONCLUSION

In pediatric heart transplant patients, native T1 values identify acute rejection requiring treatment and may identify graft dysfunction. CMR shows promise as an important tool for evaluation of cardiac grafts in children, with T1 imaging outperforming biopsy findings in the assessment of rejection.

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.

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.

Evaluation after Orthotopic Heart Transplant: What the Radiologist Should Know

Orthotopic heart transplant (OHT) is the treatment of choice for end-stage heart disease. As OHT use continues and postoperative survival increases, multimodality imaging evaluation of the transplanted heart will continue to increase. Although some of the imaging is performed and interpreted by cardiologists, a substantial proportion of images are read by radiologists. Because there is little to no consensus on a systematic approach to patients after OHT, radiologists must become familiar with common normal and abnormal posttreatment imaging features. Intrinsic transplant-related complications may be categorized on the basis of time elapsed since transplant into early (0-30 days), intermediate (1-12 months), and late (>12 months) stages. Although there can be some overlap between stages, it remains helpful to consider the time elapsed since surgery, because some complications are more common at certain stages. Recognition of differing OHT surgical techniques and their respective postoperative imaging features helps to avoid image misinterpretation. Expected early postoperative findings include small pneumothoraces, pleural effusions, pneumomediastinum, pneumopericardium, postoperative atelectasis, and an enlarged cardiac silhouette. Early postoperative complications also can include sternal dehiscence and various postoperative infections. The radiologist's role in the evaluation of allograft failure and rejection, endomyocardial biopsy complications, cardiac allograft vasculopathy, and posttransplant malignancy is highlighted. Because clinical manifestations of disease may be delayed in transplant recipients, radiologists often recognize postoperative complications on the basis of imaging and may be the first to suggest a specific diagnosis and thus positively affect patient outcomes. Online supplemental material is available for this article. ^©RSNA, 2019.

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.

Diagnostic Cardiac Catheterization in the Pediatric Population

Although the utility of diagnostic cardiac catheterization in the clinical setting has diminished over the last years, due to the emergence of noninvasive imaging modalities, such as echocardiography, magnetic resonance imaging and computed tomography, catheterization for diagnostic reasons still constitutes a valuable tool in certain parts in the workup of pediatric heart disease. As a result, awareness of the main aspects of diagnostic catheterization is of great importance for the clinical cardiologist. In this article, the main variables measured and the main actions performed during diagnostic cardiac catheterization in children are discussed.

Heart Transplant in Asia

The prevalence of heart failure has increased in Asia. A significant proportion of patients with heart failure and left ventricular dysfunction end up with advanced heart failure or end-stage heart disease. These patients may be placed on the waiting list for heart transplant. There are more than 10 countries in Asia that have an active heart transplant program. The number of heart transplants performed is limited despite an increase in the number of patients with end-stage heart failure mainly because of donor shortage, which may be related to religious belief and inefficient allocation policy.

Heart transplantation in endstage rheumatic heart disease-experience of an endemic area

BACKGROUND

Rheumatic heart disease (RHD) remains a significant cause of cardiovascular disease in developing countries. The nonsuppurative cardiovascular sequel of group A streptococcal infection is sustained inflammatory and immune reactions toward the myocardium and valves. This study attempted to determine the long-term outcome of heart transplantation in endstage RHD patients.Methods and Results:The 23 patients with endstage RHD at National Taiwan University Hospital between June 1987 and March 2012 were enrolled. In the same period, 226 dilated cardiomyopathy (DCM) patients were enrolled as the control group. The RHD group experienced more right ventricular failure and higher central venous pressure than the control group, which resulted in impaired liver and kidney function. The RHD patients had a lower 15-year survival rate than the DCM patients after transplantation (22.7% vs. 45.7%, P=0.038) and higher incidence of tricuspid regurgitation than the control group (32.2% vs. 11.4%). No differences existed between the groups for the mitral regurgitation rate (RHD 37.7% vs. DCM 29.4%, P=0.562).

CONCLUSIONS

Preoperatively, the RHD patients suffered more tricuspid regurgitation than the control group. The aortic and mitral valves in both groups functioned well over the long term. Heart transplantation for endstage RHD had a long-term survival rate that was inferior to that for DCM patients.