Comparative Analysis of the Complications of 5347 Endomyocardial Biopsies Applied to Patients After Heart Transplantation and With Cardiomyopathies: A Single-center Study

Toward cardiac tissue characterization using machine learning and light-scattering spectroscopy

SIGNIFICANCE

The non-destructive characterization of cardiac tissue composition provides essential information for both planning and evaluating the effectiveness of surgical interventions such as ablative procedures. Although several methods of tissue characterization, such as optical coherence tomography and fiber-optic confocal microscopy, show promise, many barriers exist that reduce effectiveness or prevent adoption, such as time delays in analysis, prohibitive costs, and limited scope of application. Developing a rapid, low-cost non-destructive means of characterizing cardiac tissue could improve planning, implementation, and evaluation of cardiac surgical procedures.

AIM

To determine whether a new light-scattering spectroscopy (LSS) system that analyzes spectra via neural networks is capable of predicting the nuclear densities (NDs) of ventricular tissues.

APPROACH

We developed an LSS system with a fiber-optics probe and applied it for measurements on cardiac tissues from an ovine model. We quantified the ND in the cardiac tissues using fluorescent labeling, confocal microscopy, and image processing. Spectra acquired from the same cardiac tissues were analyzed with spectral clustering and convolutional neural networks (CNNs) to assess the feasibility of characterizing the ND of tissue via LSS.

RESULTS

Spectral clustering revealed distinct groups of spectra correlated to ranges of ND. CNNs classified three groups of spectra with low, medium, or high ND with an accuracy of 95.00  ±  11.77  %   (mean and standard deviation). Our analyses revealed the sensitivity of the classification accuracy to wavelength range and subsampling of spectra.

CONCLUSIONS

LSS and machine learning are capable of assessing ND in cardiac tissues. We suggest that the approach is useful for the diagnosis of cardiac diseases associated with changes of ND, such as hypertrophy and fibrosis.

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.

The State of the Heart Biopsy: A Clinical Review

Endomyocardial biopsy (EMB) is an invaluable and underused diagnostic tool for myocardial disease. The primary indications are surveillance of cardiac allograft rejection and the diagnosis of inflammatory and infiltrative cardiomyopathies. EMB is typically performed by sampling the right ventricular septum via the right internal jugular vein using fluoroscopic guidance. The diagnostic yield of EMB is improved by sampling both ventricles and with the use of guidance from imaging or electroanatomic mapping. The risk of major cardiac complications is operator dependent and < 1% in experienced centres. EMB is the gold standard and most common form of cardiac allograft rejection surveillance, whereas advanced cardiac imaging and donor-specific antibody quantification provide complementary information. Gene expression profiling is an alternative surveillance strategy to EMB for low-risk patients. EMB is recommended for myocarditis and can guide therapy for giant-cell myocarditis, necrotizing eosinophilic myocarditis, sarcoidosis, and immune checkpoint inhibitor myocarditis. There is growing interest in using EMB to guide therapy for viral myocarditis, although the uptake of this approach is limited to specialized centres. EMB has been replaced as a first-line test for infiltrative cardiomyopathy by nonbiopsy diagnostic techniques, but is still useful to clarify the diagnosis or disease subtype. The miniaturization of bioptomes and advances in laboratory techniques such as microarrays promises to improve the safety and yield of EMB. We review the contemporary use of EMB for cardiac allograft rejection, inflammatory cardiomyopathy, and infiltrative cardiomyopathy.

Improving Endo-Myocardial Biopsy by Real-Time Spectral Tissue Sensing: A Feasibility Study

Objective: The aim of this research is to integrate spectral tissue sensing technology inside a cardiac bioptome for real-time measurements of tissue characteristics. Methods: Bioptome tip and handle components were designed and manufactured to house and guide optical fibers. The designed components were assembled on a cardiac bioptome together with optical fibers. A technical feasibility test was carried out to study the functionality of the instrument and the effect of the optical technology on the biopsy performance. Biopsy samples were taken from five different tissue types in a porcine heart and the resulting optical spectra were compared. Results: Spectral tissue sensing fibers were successfully integrated inside a conventional cardiac bioptome. The integrated instrument allowed differentiation between ventricular tissue, blood, and cardiac fat tissue based on blood and fat percentage and amount of scattering. Moreover, differences between scarred and non-scarred tissue were clearly visible. Conclusion: A first step has been made in the use of spectral tissue sensing for the detection of different tissue structures for endo-myocardial biopsy. The instrument was able to differentiate between various tissues, as well as between healthy and diseased cardiac tissues. Future research should focus on measurements of naturally diseased cardiac tissue, repeated measurements with statistical value, and improvements to the instrument design. Significance: Having the ability to measure tissue characteristics prior to acquiring a biopsy sample will not only allow easier positioning of the bioptome at the correct location, but can also prevent sampling undesired tissue or scar tissue from previous biopsies.

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.

Use of speckle-tracking echocardiography-derived strain and systolic strain rate measurements to predict rejection in transplant hearts with preserved ejection fraction

BACKGROUND

Noninvasive diagnosis of allograft rejection in heart transplant recipients is challenging. The utility of 2-dimensional speckle-tracking echocardiography (2D-STE) to predict severe rejection in heart transplant recipients with preserved left ventricular ejection fraction (LVEF) was evaluated.

METHODS

Adult heart transplant patients with preserved LVEF (> 55%) and severe rejection by biopsy (Rejection Grade ≥ 2R) or no rejection between 1997 and 2011 at the Mayo Clinic in Rochester, Minnesota were evaluated. Transthoracic echocardiography was performed within 1 month of the biopsy. LV global longitudinal and circumferential strain and strain rates (GLS, GLSR, GCS, and GCSR) were analyzed retrospectively.

RESULTS

Of 65 patients included, 25 had severe rejection and 40 were normal transplant controls without rejection. Both groups had more men than women (64 and 75%, respectively). Baseline clinical variables were similar between the groups. Both groups had normal LVEF (64.3% vs 64.5%; P = .87). All non-strain echocardiographic variables were similar between the 2 groups. Strain analysis showed significantly increased early diastolic longitudinal strain rate (P = .02) and decreased GCS (P < .001) and GCSR (P = .02) for the rejection group compared with the control group. The area under the receiver operating characteristic curve for GCS was 0.77. With a GCS cutoff of - 17.60%, the sensitivity and specificity of GCS to detect severe acute rejection were 81.8 and 68.4%, respectively.

CONCLUSIONS

2D-STE may be useful in detecting severe transplant rejection in heart transplant patients with normal LVEF.

Comparison of Utilization Trends, Indications, and Complications of Endomyocardial Biopsy in Native Versus Donor Hearts (from the Nationwide Inpatient Sample 2002 to 2014)

Native heart endomyocardial biopsy (NH-EMB) is an infrequently performed procedure. The objective of this study is to describe utilization trends, indications, and complications associated with NH-EMB in the United States and compare them with transplanted heart endomyocardial biopsy (TH-EMB). Using the Healthcare Cost and Utilization Project National Inpatient Sample database, we identified 71,105 adult patients undergoing EMB in the inpatient setting in participating hospitals from 2002 to 2014. A total of 20,770 (29%) were performed on NHs (mean age 52.2 ± 15.3, 61% men). Approximately half of patients were white and mean Charlson co-morbidity index was 1.97 ± 1.6. Common indications for NH-EMB included a suspected primary cardiomyopathy (disorder confined to the myocardium), heart failure without cardiogenic shock, and acute myocarditis. Less common indications included heart failure with cardiogenic shock, unexplained heart failure with ventricular tachycardia or high-degree atrioventricular block, and cardiac neoplasms. Complications included pericardial effusion (3.8%), third-degree atrioventricular block (2.7%), vascular complications (1.9%), and deep venous thrombosis (3.5%), in others. Predictors of complications included presence of a cardiac malignant neoplasm, use of hemodynamic support, heart failure with ventricular tachyarrhythmias, and female gender. Compared with NH-EMB, TH-EMB was associated with lower rates of pericardial effusion, third-degree atrioventricular block, ventricular tachyarrhythmias requiring cardioversion, and higher rates of deep venous thrombosis, infections, and pneumothorax. NH-EMB utilization is low in the United States and constitutes less than 1/3 of all EMBs performed.

Reducing Fluoroscopic Radiation Exposure During Endomyocardial Biopsy in Pediatric Transplant Recipients

Endomyocardial biopsy (EMB) with fluoroscopy is used for rejection surveillance in pediatric heart transplantation. Lowering frame rate may reduce radiation, but decreases temporal resolution and image quality. We undertook a quality initiative reducing frame rate from 10 frames per second (FPS) to 5 FPS. To assess whether lowering frame rate can reduce radiation exposure without compromising safety, data on EMBs from 9/2009 to 4/2013 without angiography or intervention were reviewed. Effective dose was calculated from dose area product (DAP) and fluoroscopy time. Complications were reviewed. Independent t test compared pre- and post-data and a general linear model were used to control for confounders. Paired t test of most proximate data was used for pts with EMB before and after our change. Eighty-six patients had 543 EMB. After adjusting for weight, attending, and presence of a fellow, the lower FPS group had a 60.3% reduction in DAP (p < 0.0001) and 53.8% drop in effective dose (p < 0.0001). Fluoroscopy time did not differ. Twenty-eight pts had EMBs both before and after the FPS change. Pair-wise analysis of this group demonstrated a 33% reduction in DAP (p < 0.05) and 37% drop in effective dose (p < 0.01), without difference in fluoroscopy time. No patient had an increase in TR > 1 grade by ECHO. There were no deaths or perforations. Lowering the frame rate reduces radiation exposure by >50% without compromising safety. Efforts to further minimize radiation exposure of this vulnerable population should be considered.

Endomyocardial biopsy via the femoral access - still safe and valuable diagnostic tool

BACKGROUND

The endomyocardial biopsy has proven to be an integral diagnostic tool for surveillance of cardiac allograft rejection and identification of myocardial diseases. Nevertheless, this invasive procedure is not risk-free. This study focuses on the risk of complications and diagnostic performance of right ventricular endomyocardial biopsy (EMB).

METHODS

In this single-center retrospective study, we analyzed 315 EMB procedures performed between July 2008 and May 2015 in 73 patients. All EMBs were made via the right femoral vein approach under fluoroscopic control to evaluate suspected myocarditis, unclear heart failure, unexplained cardiomyopathy, assumed infiltrative and storage disease or as a part of routine allograft rejection monitoring and clinically suspected rejection diagnosis after heart transplantation (HTx). Obtained specimens were diagnosed histopathologically by one experienced pathologist. All patients underwent a 12-lead electrocardiogram (ECG), ECG monitoring, transthoracic echocardiography before and after EMB to obtain a detailed assessment of the incidence of heart rhythm disorders, pericardial effusions or worsening valve insufficiency. Complications resulting from the procedure were classified as major or minor according to the risk of death.

RESULTS

Among all the 315 biopsies, 86.67% were performed in 32 patients after HTx, 3.81% in patients with myocarditis, 2.54% in patients with dilated cardiomyopathy and 1.9% in patients with amyloidosis. The overall complications rate was 1.9% (6 of 315 procedures). Major complications included perforation with pericardial tamponade requiring surgical intervention (0.64%, 2 of 315 procedures). Minor complications included: pericardial effusion (0.32%, 1 of 315 procedures), local hematoma (0.64%, 2 of 315 procedures) and right coronary artery-right ventricle fistula in HTx recipient (0.32%, 1 of 315 procedures).

CONCLUSIONS

EMB is a safe procedure with low risk of serious complications and high effectiveness for the evaluation of unexplained left ventricle dysfunction and monitoring allograft rejection after HTx.

Variation in the use of surveillance endomyocardial biopsy among pediatric heart transplant centers over time

EMB is widely utilized for graft surveillance after HTx; however, there is significant variation in the frequency of surveillance EMB use during the first year post-HTx. The aim of this study was to assess changes in the utilization of surveillance EMB over time among member institutions of PHTS. A survey of PHTS centers assessing the frequency of surveillance EMB use during the first year post-HTx was conducted in 2006. The same survey was repeated in 2014 to assess changes in practice over time. The number of EMB in infants ranged from 0 to 9 and in adolescents 0 to 16. The number of EMB decreased or remained unchanged in the majority of centers. Fewer EMB are performed in infants compared to adolescents and this practice did not change over time. There was a significant decrease in surveillance EMB use in adolescents (p = 0.012). International centers perform significantly fewer EMB in adolescents when compared to centers within the United States (p = 0.006). There continues to be significant variation in the utilization of surveillance EMB, with a shift toward less reliance on EMB for adolescents in the current era. Further research is necessary to determine the optimal frequency of invasive monitoring that reduces costs without compromising outcomes.

Mitral Valve Regurgitation: A Severe Complication following Left Ventricular Biopsy 15 Years after Heart Transplantation

A 71-year-old male patient underwent orthotopic heart transplantation in 1995. Due to left heart catheterization 15 years later, biopsy from the left ventricular apex was performed for rejection screening. Two days later, echocardiography revealed severe mitral valve regurgitation requiring mitral valve replacement. This is a very rare case showing that left heart biopsy may lead to severe hemodynamic complications with the need for surgical intervention.