Routine surveillance endomyocardial biopsy: late rejection after heart transplantation

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.

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.

Bayesian analysis of recurrent event with dependent termination: an application to a heart transplant study

For a heart transplant patient, the risk of graft rejection and risk of death are likely to be associated. Two fully specified Bayesian models for recurrent events with dependent termination are applied to investigate the potential relationships between these two types of risk as well as association with risk factors. We particularly focus on the choice of priors, selection of the appropriate prediction model, and prediction methods for these two types of risk for an individual patient. Our prediction tools can be easily implemented and helpful to physicians for setting heart transplant patients' biopsy schedule.

Cardiac Transplant Biopsies

The endomyocardial biopsy remains the gold standard for assessing the status of the transplanted heart. It is the most consistently reliable method for the diagnosis and grading of acute cellular and antibody-mediated rejection. Recognition of specimen artifacts and other biopsy findings such as ischemic injury, Quilty effect, infection, and post-transplant lymphoproliferative disorder is important for accurate biopsy interpretation and differentiation from rejection. The endomyocardial biopsy provides important diagnostic information essential for optimal management of cardiac transplant recipients.

Gene-expression profiling for rejection surveillance after cardiac transplantation

BACKGROUND

Endomyocardial biopsy is the standard method of monitoring for rejection in recipients of a cardiac transplant. However, this procedure is uncomfortable, and there are risks associated with it. Gene-expression profiling of peripheral-blood specimens has been shown to correlate with the results of an endomyocardial biopsy.

METHODS

We randomly assigned 602 patients who had undergone cardiac transplantation 6 months to 5 years previously to be monitored for rejection with the use of gene-expression profiling or with the use of routine endomyocardial biopsies, in addition to clinical and echocardiographic assessment of graft function. We performed a noninferiority comparison of the two approaches with respect to the composite primary outcome of rejection with hemodynamic compromise, graft dysfunction due to other causes, death, or retransplantation.

RESULTS

During a median follow-up period of 19 months, patients who were monitored with gene-expression profiling and those who underwent routine biopsies had similar 2-year cumulative rates of the composite primary outcome (14.5% and 15.3%, respectively; hazard ratio with gene-expression profiling, 1.04; 95% confidence interval, 0.67 to 1.68). The 2-year rates of death from any cause were also similar in the two groups (6.3% and 5.5%, respectively; P=0.82). Patients who were monitored with the use of gene-expression profiling underwent fewer biopsies per person-year of follow-up than did patients who were monitored with the use of endomyocardial biopsies (0.5 vs. 3.0, P<0.001).

CONCLUSIONS

Among selected patients who had received a cardiac transplant more than 6 months previously and who were at a low risk for rejection, a strategy of monitoring for rejection that involved gene-expression profiling, as compared with routine biopsies, was not associated with an increased risk of serious adverse outcomes and resulted in the performance of significantly fewer biopsies. (ClinicalTrials.gov number, NCT00351559.)

Has the 2004 revision of the International Society of Heart and Lung Transplantation grading system improved the reproducibility of the diagnosis and grading of cardiac transplant rejection?

We compared the interobserver reproducibility of the 1990 and 2004 International Society for Heart and Lung Transplantation (ISHLT) grading system for cardiac rejection. The 2004 ISHLT grading system for cardiac allograft rejection did not improve reproducibility partly due to pathologists' disagreement in diagnosing Grades 1B/1R and 3A/2R rejection. To achieve better reproducibility, better criteria for defining 1B/1R vs. 3A/2R rejection and markers of myocyte injury are needed.

B-type natriuretic peptide is a sensitive screening test for acute rejection in pediatric heart transplant patients

BACKGROUND

The utility of B-type natriuretic peptide (BNP) for detecting acute rejection (AR) is unclear. The purpose of our study was to evaluate BNP as a screening test for AR in pediatric heart transplant patients.

METHODS

All endomyocardial biopsies (EMBs) with concurrent BNP levels from February 2004 through March 2007 at the study institution were reviewed and the association between BNP levels and acute rejection was assessed.

RESULTS

Eighty-six patients underwent a total of 560 EMBs. The median age at EMB was 10.5 years (interquartile range [IQR] 3.7 to 15.4 years). There were 59 episodes of AR, 32 (54%) occurring at <1 year post-transplant. BNP levels were higher in patients with AR, median 387 pg/ml (IQR 125 to 931 pg/ml), compared with those without AR, median 66 pg/ml (IQR 37 to 148 pg/ml) (p < 0.001). The receiver operating characteristic (ROC) curve for BNP demonstrated an area under the curve (AUC) of 0.82 (95% confidence interval [CI] 0.76 to 0.88) (p < 0.001). A BNP level of 100 pg/ml corresponded to a sensitivity of 0.85 (95% CI 0.73 to 0.92) and a negative predictive value (NPV) of 0.97 (95% CI 0.95 to 0.99) for detecting AR. The ROC curve for patients at >1 year post-transplant demonstrated an AUC of 0.86 (95% CI 0.80 to 0.93) (p < 0.001), and a BNP level of 100 pg/ml corresponded to a sensitivity of 0.96 (95% CI 0.79 to 0.99) and NPV of 0.994 (95% CI 0.962 to 0.999) for detecting AR.

CONCLUSIONS

BNP levels have a high sensitivity and NPV for evaluating AR in pediatric heart transplant patients. In patients >1 year post-transplant, a BNP level of <100 pg/ml correlates with a <1% chance of AR and may obviate the need for EMB in some cases.

Is It Possible to Reduce the Number of Endomyocardial Biopsies With New Immunosuppressive Drugs?

INTRODUCTION

Using previous immunosuppressive regimens the considerable number of rejections of heart transplantations required routine surveillance myocardial biopsies, particularly during the early months. More effective immunosuppressive regimens would probably allow routine biopsies to be reduced. Our objectives were to assess the incidence of and the time to rejection with a new immunosuppressive protocol, considering the possibility of reducing the number of routine biopsies.

MATERIALS AND METHODS

We undertook a retrospective study of patients who had undergone heart transplantation from January 2002 to August 2005 and who received induction therapy with Daclizumab (two doses) and maintenance therapy with tacrolimus + mycophenolate + low doses of steroids.

RESULTS

Among 42 patients, 13 (31%) showed myocardial rejection in the first 3 months. All episodes were grade 3A and none had hemodynamic consequences. After 3 months, three patients (7.1%) experienced 3A rejection and 1 (2.4%), grade 4 acute rejection after ceasing medical treatment. Each episode of rejection was predictable, either owing to reduction in immunosuppression therapy or to a previous history of rejection.

CONCLUSIONS

The majority of rejection episodes occur in the first 3 months posttransplantation. After that time, the incidence of rejection is less and clinically predictable. Therefore, surveillance biopsies should be limited to the first 3 months, and performed later either in symptomatic patients (with a history of previous rejection) or in those whose immunosuppressive therapy needs to be reduced.

Allograft rejection of ISHLT grade >/=3A occurring late after heart transplantation--a distinct entity?

BACKGROUND

The significance of International Society of Heart and Lung Transplantation (ISHLT) grade >/=3A rejection detected by routine endomyocardial biopsies beyond 2 years post-transplant remains uncertain.

METHODS

We performed a retrospective analysis of our single-institution database consisting of 4,041 biopsies (188 patients) from 1986 to 2001. Incidence, clinical correlates and outcome of ISHLT grade >/=3A rejection beyond 2 years post-transplant were analyzed.

RESULTS

A total of 307 ISHLT grade >/=3A rejection episodes was diagnosed up to 10 years after transplantation, 69 of which occurred later than 2 years post-transplant in 33 of 139 patients ("late rejection") at therapeutic levels of immunosuppression. Late rejection was only marginally correlated with the incidence of moderate rejection within the first 2 post-transplant years (p = 0.09). The incidence of moderate rejection per patient-year decreased from 1.05 in Year 1 over 0.11 in Year 5 to 0.04 in Year 10. The technical failure rate of biopsies remained low throughout the post-transplant period (range 0.7% to 2.4%). Spontaneous resolution of ISHLT grade >/=3A rejection beyond 2 years post-transplant occurred in all 17 patients in whom specific anti-rejection therapy had been electively withheld. Mortality beyond 2 years post-transplant was lower (p = 0.033) in the "late rejecting" group (n = 33) than in the control group (n = 106).

CONCLUSIONS

Endomyocardial biopsy continues to detect episodes of moderate rejection even very late after heart transplantation, without a close correlation with the rejection frequency in the early post-transplant period. Even without specific treatment, late rejection carries a benign clinical prognosis and may represent a separate biologic entity. Potential long-term effects-for instance, on the pathogenesis of transplant vasculopathy-need further elucidation.

Routine surveillance endomyocardial biopsy continues to detect significant rejection late after heart transplantation

BACKGROUND

The need for continued surveillance endomyocardial biopsies beyond the first year after cardiac transplantation is controversial. We evaluated the incidence of rejections requiring treatment (International Society Heart and Lung Transplantation grade 3A or greater) in patients 5 years or more after heart transplantation.

METHODS

We conducted a retrospective chart review of all patients who underwent at least 1 endomyocardial biopsy at our center 5 years or more after heart transplantation.

RESULTS

A total of 461 biopsies were performed in 77 patients 5 or more years after heart transplantation. Nine episodes of grade 3A or greater rejection were identified in 8 of 77 patients (10%). During the first year, 7.6% of biopsies were grade 3A or greater. Grade 3A rejection occurred in approximately 3.5% to 4% of biopsies during years 2 to 7. The overall incidence of procedural related complications at our institution was < 0.5%.

CONCLUSION

Endomyocardial biopsies continue to detect clinically significant rejection beyond 5 years after cardiac transplantation. The overall incidence of procedural related complications requiring treatment was low and none was life threatening. The absence of early rejection does not predict freedom from late rejection. Therefore, we continue to recommend surveillance biopsies in cardiac transplant recipients late after transplantation.