Diagnostic use of the endomyocardial biopsy: a consensus statement

Storytelling of Myocarditis

In 1900, Fiedler first reported autopsy cases with peculiar inflammation of the myocardium, which he named interstitial myocarditis. He postulated an isolated cardiac inflammation of the myocardium in the absence of multiorgan involvement and with a poor prognosis due to invisible microorganisms, which years later would have been identified as viruses. The revision of original histologic sections by Schmorl showed cases with lymphocytes and others with giant-cell inflammatory histotypes. The in vivo diagnosis of myocarditis became possible thanks to right cardiac catheterization with endomyocardial biopsy (EMB). The gold standard for diagnosis was achieved with the employment of immunohistochemistry and molecular investigation by Polymerase Chain Reaction (PCR), which allows for the detection of viruses as causal agents. Both RNA and DNA were revealed to be cardiotropic, with a common receptor (CAR). A protease, coded by coxsackie virus, disrupts the cytoskeleton and accounts for cell death. Unfortunately, vaccination, despite having been revealed to be effective in animal experiments, has not yet entered the clinical field for prevention. Cardiac Magnetic Resonance turned out to be a revolutionary tool for in vivo diagnosis through the detection of edema (inflammatory exudate). Myocarditis may be fulminant in terms of clinical presentation but not necessarily fatal. The application of ExtraCorporeal Membrane Oxygenation (ECMO) allows for relieving the overloaded native heart.

Dilated cardiomyopathy: causes, mechanisms, and current and future treatment approaches

Dilated cardiomyopathy is conventionally defined as the presence of left ventricular or biventricular dilatation or systolic dysfunction in the absence of abnormal loading conditions (eg, primary valve disease) or significant coronary artery disease sufficient to cause ventricular remodelling. This definition has been recognised as overly restrictive, as left ventricular hypokinesis without dilation could be the initial presentation of dilated cardiomyopathy. The causes of dilated cardiomyopathy comprise genetic (primary dilated cardiomyopathy) or acquired factors (secondary dilated cardiomyopathy). Acquired factors include infections, toxins, cancer treatment, endocrinopathies, pregnancy, tachyarrhythmias, and immune-mediated diseases. 5-15% of patients with acquired dilated cardiomyopathy harbour a likely pathogenic or pathogenic gene variant (ie, gene mutation). Therefore, the diagnostic tests and therapeutic approach should always consider both genetic and acquired factors. This Seminar will focus on the current multidimensional diagnostic and therapeutic approach and discuss the underlying pathophysiology that could drive future treatments aiming to repair or replace the existing gene mutation, or target the specific inflammatory, metabolic, or pro-fibrotic drivers of genetic or acquired dilated cardiomyopathy.

Myocarditis as a Complication of Campylobacter jejuni-Associated Enterocolitis: A Report of Two Cases

Myocarditis refers to inflammation of the heart muscle and may occur individually or together with pericarditis, which refers to inflammation of the saclike tissue layer that surrounds the heart. They may have infectious or non-infectious etiologies. Campylobacter jejuni, a major cause of gastroenteritis worldwide, may also cause myocarditis in rare situations. We present two cases highlighting this rare complication of diarrheal disease caused by Campylobacter jejuni infection and subsequent development of myocarditis. Both patients presented with chest pain and multiple episodes of watery diarrhea, with initial EKGs showing ST segment changes, as well as elevated inflammatory markers and elevated troponins. GI panels for both patients were positive for Campylobacter jejuni. Based on their presentations and investigative findings, they were diagnosed with myocarditis secondary to Campylobacter infection, and their symptoms subsided with appropriate management. It is unclear if the myocardial damage, in this case, is a direct effect of the toxin on cardiac myocytes or secondary to an immunologic phenomenon. Regardless, Campylobacter jejuni-associated myocarditis remains a rare phenomenon and needs to be considered in the differential of patients presenting with concurrent chest pain and diarrheal symptoms.

Myocarditis and endomyocardial biopsy: achieving consensus diagnosis on 100 cases

The two histopathology benchmarks used to diagnose myocarditis are the Dallas Criteria, developed in 1984 and the European Society of Cardiology criteria, developed in 2013, which added immunohistochemistry for the detection of CD3+ T cells (lymphocytes) and CD68+ macrophages. Despite their near universal acceptance, the extent to which pathologists use these criteria or their own criteria to consistently render the diagnosis of myocarditis on endomyocardial biopsy (EMB) is unknown. We digitally scanned slides from 100 heart biopsies, including a trichrome stain and immunostaining, that were chosen as representative of myocarditis, non-myocarditis, and borderline myocarditis, as diagnosed per one institution's use of the Dallas Criteria. Eight blinded international cardiovascular experts were asked to render diagnoses and offer a confidence score on each case. No clinical histories were shared. There was full initial agreement across all experts on 37 cases (16 myocarditis and 21 non-myocarditis) and moderate consensus on 35 cases. After individual inquiries and group discussion, consensus was reached on 90 cases. Diagnostic confidence was highest among the myocarditis diagnoses, lowest for borderline cases, and significantly different between the three diagnostic categories (myocarditis, borderline myocarditis, non-myocarditis; P-value=8.49 × 10^-57; ANOVA). Diagnosing myocarditis, particularly in cases with limited inflammation and injury, remains a challenge even for experts in the field. Intermediate cases, termed "borderline" in the Dallas Criteria, represent those for which consensus is particularly hard to achieve. To increase consistency for the histopathologic diagnosis of myocarditis, we will need more specifically defined criteria, more granular descriptions of positive and negative features, clarity on how to incorporate immunohistochemistry findings, and improved nomenclature.

Cardiac Toxicity Associated with Immune Checkpoint Inhibitors: A Systematic Review

Immune checkpoint inhibitors (ICIs) are an important advancement in the field of cancer treatment, significantly improving the survival of patients with a series of advanced malignancies, like melanoma, non-small cell lung cancer (NSCLC), hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), and Hodgkin lymphoma. ICIs act upon T lymphocytes and antigen-presenting cells, targeting programmed cell death protein 1 (PD1), programmed cell death protein ligand 1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4), breaking the immune tolerance of the T cells against malignant cells and enhancing the body's own immune response. A variety of cardiac-adverse effects are associated with ICI-based treatment, including pericarditis, arrhythmias, cardiomyopathy, and acute coronary syndrome, with myocarditis being the most studied due to its often-unexpected onset and severity. Overall, Myocarditis is rare but presents an immune-related adverse event (irAE) that has a high fatality rate. Considering the rising number of oncological patients treated with ICIs and the severity of their potential adverse effects, a good understanding and continuous investigation of cardiac irAEs is of the utmost importance. This systematic review aimed to revise recent publications (between 2016-2022) on ICI-induced cardiac toxicities and highlight the therapeutical approach and evolution in the selected cases.

Transcriptional Active Parvovirus B19 Infection Predicts Adverse Long-Term Outcome in Patients with Non-Ischemic Cardiomyopathy

Parvovirus B19 (B19V) is the predominant cardiotropic virus currently found in endomyocardial biopsies (EMBs). However, direct evidence showing a causal relationship between B19V and progression of inflammatory cardiomyopathy are still missing. The aim of this study was to analyze the impact of transcriptionally active cardiotropic B19V infection determined by viral RNA expression upon long-term outcomes in a large cohort of adult patients with non-ischemic cardiomyopathy in a retrospective analysis from a prospective observational cohort. In total, the analyzed study group comprised 871 consecutive B19V-positive patients (mean age 50.0 ± 15.0 years) with non-ischemic cardiomyopathy who underwent EMB. B19V-positivity was ascertained by routine diagnosis of viral genomes in EMBs. Molecular analysis of EMB revealed positive B19V transcriptional activity in n = 165 patients (18.9%). Primary endpoint was all-cause mortality in the overall cohort. The patients were followed up to 60 months. On the Cox regression analysis, B19V transcriptional activity was predictive of a worse prognosis compared to those without actively replicating B19V (p = 0.01). Moreover, multivariable analysis revealed transcriptional active B19V combined with inflammation [hazard ratio 4.013, 95% confidence interval 1.515–10.629 (p = 0.005)] as the strongest predictor of impaired survival even after adjustment for age and baseline LVEF (p = 0.005) and independently of viral load. The study demonstrates for the first time the pathogenic clinical importance of B19V with transcriptional activity in a large cohort of patients. Transcriptionally active B19V infection is an unfavourable prognostic trigger of adverse outcome. Our findings are of high clinical relevance, indicating that advanced diagnostic differentiation of B19V positive patients is of high prognostic importance.

Viral Myocarditis-From Pathophysiology to Treatment

The diagnosis of acute and chronic myocarditis remains a challenge for clinicians. Characterization of this disease has been hampered by its diverse etiologies and heterogeneous clinical presentations. Most cases of myocarditis are caused by infectious agents. Despite successful research in the last few years, the pathophysiology of viral myocarditis and its sequelae leading to severe heart failure with a poor prognosis is not fully understood and represents a significant public health issue globally. Most likely, at a certain point, besides viral persistence, several etiological types merge into a common pathogenic autoimmune process leading to chronic inflammation and tissue remodeling, ultimately resulting in the clinical phenotype of dilated cardiomyopathy. Understanding the underlying molecular mechanisms is necessary to assess the prognosis of patients and is fundamental to appropriate specific and personalized therapeutic strategies. To reach this clinical prerequisite, there is the need for advanced diagnostic tools, including an endomyocardial biopsy and guidelines to optimize the management of this disease. The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has currently led to the worst pandemic in a century and has awakened a special sensitivity throughout the world to viral infections. This work aims to summarize the pathophysiology of viral myocarditis, advanced diagnostic methods and the current state of treatment options.

Cardiovascular consequences of viral infections: from COVID to other viral diseases

Infection of the heart muscle with cardiotropic viruses is one of the major aetiologies of myocarditis and acute and chronic inflammatory cardiomyopathy (DCMi). However, viral myocarditis and subsequent dilated cardiomyopathy is still a challenging disease to diagnose and to treat and is therefore a significant public health issue globally. Advances in clinical examination and thorough molecular genetic analysis of intramyocardial viruses and their activation status have incrementally improved our understanding of molecular pathogenesis and pathophysiology of viral infections of the heart muscle. To date, several cardiotropic viruses have been implicated as causes of myocarditis and DCMi. These include, among others, classical cardiotropic enteroviruses (Coxsackieviruses B), the most commonly detected parvovirus B19, and human herpes virus 6. A newcomer is the respiratory virus that has triggered the worst pandemic in a century, SARS-CoV-2, whose involvement and impact in viral cardiovascular disease is under scrutiny. Despite extensive research into the pathomechanisms of viral infections of the cardiovascular system, our knowledge regarding their treatment and management is still incomplete. Accordingly, in this review, we aim to explore and summarize the current knowledge and available evidence on viral infections of the heart. We focus on diagnostics, clinical relevance and cardiovascular consequences, pathophysiology, and current and novel treatment strategies.

Electroanatomic Mapping System and Intracardiac-Echo to Guide Endomyocardial Biopsy

Interest in endomyocardial biopsy (EMB) has progressively grown during the past decade. Still, its use remains limited to highly specialized centers, mostly because it is considered an invasive procedure with poor diagnostic yield and inherent complications. Indeed, the diagnostic performance of EMB is strictly linked to the sample of myocardium we can obtain. If we can precisely localize areas of diseased myocardium, sampling error or inadequate withdrawals are minimized. In this state-of-the-art review, we provide guidance on how to technically and practically perform EMB guided by electroanatomic voltage mapping and intracardiac echocardiography, and review the evidence supporting this combined approach.

Cardiac involvement in systemic sclerosis: Getting to the heart of the matter

Primary systemic sclerosis heart involvement (pSHI) is an important disease manifestation that accounts for a significant proportion of systemic sclerosis (SSc)-associated mortality. A broad clinical spectrum of pSHI exists, which ranges from asymptomatic perfusion abnormalities to diastolic dysfunction or acute myocarditis and congestive heart failure. With improving sensitivity of cardiac investigations, it is increasingly recognized that there is a large burden of subclinical cardiac disease in patients with SSc. Early signs of pSHI can be subtle and determining the etiology of cardiac abnormalities from other causes of cardiomyopathy such as hypertension, ischemic heart disease (IHD), and pulmonary vascular disease remain challenging. Early identification of pSHI potentially provides clinicians with a window of opportunity for intervention to avert progression to heart failure. However, optimal screening and treatment guidelines are lacking, and it is an area of much needed further clinical research.

[Cardiac amyloidosis]

Different types of amyloid deposits involve the heart. Transthyretin and light chain amyloidosis are the most frequent. Diagnostic performance, typing and treatments have improved in the last decade, and prognosis of cardiac amyloidosis is now significantly better thanks to targeted therapies. In this article, we will describe the clinical manifestations of cardiac amyloidosis, the diagnostic approach and detail the characteristics and specific treatments of the most frequent types of cardiac amyloidosis. We will focus on the histopathological aspects, especially on the importance of amyloid typing.

Diagnostic Yield of Electroanatomic Voltage Mapping in Guiding Endomyocardial Biopsies

BACKGROUND

Electroanatomic voltage mapping (EVM) is a promising modality for guiding endomyocardial biopsies (EMBs). However, few data support its feasibility and safety. We now report the largest cohort of patients undergoing EVM-guided EMBs to show its diagnostic yield and to compare it with a cardiac magnetic resonance (CMR)-guided approach.

METHODS

We included 162 consecutive patients undergoing EMB at our institution from 2010 to 2019. EMB was performed in pathological areas identified at EVM and CMR. CMR and EVM sensitivity and specificity regarding the identification of pathological substrates of myocardium were evaluated according to EMB results.

RESULTS

Preoperative CMR showed late gadolinium enhancement in 70% of the patients, whereas EVM identified areas of low voltage in 61%. Right (73%), left (19%), or both ventricles (8%) underwent sampling. EVM proved to have sensitivity similar to CMR (74% versus 77%), with specificity being 70% and 47%, respectively. In 12 patients with EMB-proven cardiomyopathy, EVM identified pathological areas that had been undetected at CMR evaluation. Sensitivity of pooled EVM and CMR was as high as 95%. EMB analysis allowed us to reach a new diagnosis, different from the suspected clinical diagnosis, in 39% of patients. The complications rate was low, mostly related to vascular access, with no patients requiring urgent management.

CONCLUSIONS

EVM proved to be a promising tool for targeted EMB because of its sensitivity and specificity for identification of myocardial pathological substrates. EVM was demonstrated to have accuracy similar to CMR. EVM and CMR together conferred a positive predictive value of 89% on EMB.

Myocardial micro-biopsy procedure for molecular characterization with increased precision and reduced trauma

Endomyocardial biopsy is a valuable tool in cardiac diagnostics but is limited by low diagnostic yield and significant complication risks. Meanwhile, recent developments in transcriptomic and proteomic technologies promise a wealth of biological data from minimal tissue samples. To take advantage of the minimal tissue amount needed for molecular analyses, we have developed a sub-millimeter endovascular biopsy device, considerably smaller than current clinical equipment, and devised a low-input RNA-sequencing protocol for analyzing small tissue samples. In in vivo evaluation in swine, 81% of biopsy attempts (n = 157) were successful. High quality RNA-sequencing data was generated from 91% of the sequenced cardiac micro-biopsy samples (n = 32). Gene expression signatures of samples taken with the novel device were comparable with a conventional device. No major complications were detected either during procedures or during 7 days' follow-up, despite acquiring a relatively large number of biopsies (median 30) in each animal. In conclusion, the novel device coupled with RNA-sequencing provides a feasible method to obtain molecular data from the myocardium. The method is less traumatic and has a higher flexibility compared to conventional methods, enabling safer and more targeted sampling from different parts of the myocardium.

Clinicopathological manifestations of myocarditis in a heart failure population

Myocarditis continues to present challenges in diagnosis and management. The goal of this study is to determine the occurrence and manifestations of myocarditis in a heart failure (HF) population. The analyzed patients had acute or persistent HF and were referred over a 6-year period to a quaternary HF center for advanced HF therapies including mechanical circulatory support, left ventricular assist device (LVAD) implantation, and/or heart transplantation. The histopathological diagnosis of myocarditis was made based on the presence of an inflammatory infiltrate of the myocardium, typically with associated cardiomyocyte (CMC) damage, combined as indicated with immunohistochemical and molecular biology characterization. The pathological findings were correlated with a panel of clinical parameters and clinical course of the patients. Myocarditis was identified in 36 patients, with initial diagnoses made in 10 (40%) of 25 by endomyocardial biopsy (EMB), 1 by atrial biopsy (maze procedure), 7 (2.1%) of 331 at LVAD implantation, and 18 (7.8%) of 229 in the explanted heart. There were 20 cases of lymphocytic myocarditis, 4 cases of giant cell myocarditis, 3 cases of eosinophilic myocarditis, and 9 cases of lymphohistocytic with granulomas myocarditis - cardiac sarcoidosis. EMB was performed in 25 patients and was positive in 10 (40%) of cases. Myocarditis was found in 23 explanted hearts including 18 cases de novo and 5 cases with a previously positive specimen. Of the 23 explanted hearts, 21 were nonischemic cardiomyopathy and 2 were ischemic cardiomyopathy. Our findings show that, in patients presenting to a quaternary medical center, myocarditis can be manifest as acute HF as well as a complicating factor in chronic HF.

Update on cardiomyopathies and sudden cardiac death

Sudden cardiac death (SCD) remains a leading mode of death in western countries. Since SCD can be the first and last clinical presentation of the underlying disease, autopsy could be the only medical examination available for early diagnosis and it should be performed according to the guidelines of the Association for European Cardiovascular Pathology. Although the vast majority of SCD are due to coronary artery disease, non-ischemic causes of SCD do exist and are prevalent in young people with structural (i.e. arrhythmogenic, hypertrophic and inflammatory cardiomyopathy) and non-structural (ion channel diseases) cardiomyopathies, accounting for up to one half of cases. A standardized autopsy protocol, in combination with blood sampling to ensure feasibility of postmortem molecular testing if needed, is mandatory. The pathologist is called to provide the correct diagnosis and to advice the relatives on the need of a cascade clinical and genetic screening in the presence of a heredo-familial disease.

Story telling of myocarditis

Myocarditis was discovered as heart disease at autopsy with the use of microscope. In 1900, with the name of acute interstitial myocarditis, Carl Ludwig Alfred Fiedler first reported the history of a sudden cardiac heart failure, in the absence of coronary, valve, pericardial disease or classical specific infections with multiorgan involvement. He postulated a peculiar isolated acute inflammation of the myocardium with poor prognosis due to invisible microorganisms, which years later would have been identified as viruses. Subsequent revision of Fiedler original histologic slides by Schmorl showed cases with either lymphocytic or giant cell infiltrates. The in vivo diagnosis became possible with the right heart catheterism and endomyocardial biopsy. Employment of immunohistochemistry and molecular techniques improved the diagnosis and etiology identification. The mechanism of myocyte injury by coxsackie virus was identified in protease 2A coded by the virus and disrupting the dystrophin in the cytoskeleton. Both RNA and DNA viruses may be cardiotropic, and coxsackie and adenovirus share a common receptor (CAR). Unfortunately, vaccination is not yet available. Cardiac Magnetic Resonance is a revolutionary diagnostic tool by detecting edema, of myocardial inflammation. However endomyocardial biopsy remains the gold standard for etiological and histotype diagnosis, with limited sensitivity due to sampling error. Viral lymphocytic fulminant myocarditis may not be fatal and the employment of mechanical assistant device - ECMO in acute phase for temporary support may be lifesaving with good prognosis.

Pathobiology of cardiovascular diseases: an update

This article introduces the Second Special Issue of Cardiovascular Pathology (CVP), the official journal of the Society for Cardiovascular Pathology (SCVP). This CVP Special Issue showcases a series of commemorative review articles in celebration of the 25th anniversary of CVP originally published in 2016 and now compiled into a virtual collection with online access for the cardiovascular pathology community. This overview also provides updates on the major categories of cardiovascular diseases from the perspective of cardiovascular pathologists, highlighting publications from CVP, as well as additional important review articles and clinicopathologic references.

Arrhythmias in myocarditis: State of the art

Many kinds of arrhythmias may occur in patients with myocarditis at any stage of the disease. However, compared to the other clinical presentations, arrhythmic myocarditis has been poorly described in the literature. Arrhythmias occurring in either ongoing or previous myocardial inflammation are complex and heterogeneous, and the disease itself is often underdiagnosed, thus limiting data collection and interpretation. However, different from the other clinical presentations, arrhythmic myocarditis requires specific diagnostic, prognostic, and therapeutic considerations. The aim of this review is to critically summarize the state of the art on myocarditis presenting with arrhythmias in terms of epidemiology, etiology, diagnosis, prognosis, and treatment.

An unusual presentation of prominent crista terminalis mimicking a right atrial mass: a case report

Background

The crista terminalis is a variation of normal anatomical structure within the right atrium which may be misdiagnosed with an abnormal atrial mass normally visualized in the standard views on the transthoracic echocardiogram.

Case presentation

In this case presentation, we demonstrated a rare case report describing the accidental discovery of a right atrial mass-like structure in a 54-year old Asian man without physical discomfort during an echocardiographic examination. These findings naturally caused some concern as the differential diagnosis such as right atrial myxoma or thrombus and further examination were organized. The subsequent positron emission tomography/magnetic resonance imaging (PET/MRI) differentiated a true right atrial mass from a strip extending into the atrium in accordance with prominent crista terminalis.

Conclusion

A preferable understanding of the complex anatomy and PET/MRI appearance of a prominent crista terminalis will minimize the misdiagnosis of this structure and avoiding unnecessary anxiety and more invasive examinations.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0925-y) contains supplementary material, which is available to authorized users.

Electroanatomical mapping systems and intracardiac echo integration for guided endomyocardial biopsy

INTRODUCTION

During the past years, endomyocardial biopsy (EMB) has gradually spread into clinical practice. However, the role of EMB in the diagnosis and treatment of cardiovascular diseases remains a controversial issue, especially in the setting of unexplained ventricular arrhythmias. Areas covered: This review describes the methodology of EMB guided by combined use of three-dimensional electroanatomical mapping systems and intracardiac echo and summarizes the classical, fluoroscopy-guided EMB technique. Finally, the personal experience acquired with the 'electrophysiologist-made' integration methodology has been reported. Expert commentary: Since EMB has been considered in the setting of arrhythmogenic cardiomyopathy, myocarditis, cardiac sarcoidosis, drug toxicity, and/or other diseases causing malignant ventricular arrhythmias, the electrophysiologists have started to perform firsthand biopsy. The electrophysiologists introduced the use of electroanatomical mapping systems and intracardiac echo. This new methodology improved significantly biopsy diagnostic yield and allowed to reduce complications.

Targeted endomyocardial biopsy guided by real-time cardiovascular magnetic resonance

BACKGROUND

Endomyocardial biopsies (EMB) are an important diagnostic tool for myocarditis and other infiltrative cardiac diseases. Routinely, biopsies are obtained under fluoroscopic guidance with a substantial radiation burden. Despite procedural success, there is a large sampling error caused by missing the affected myocardium. Therefore, multiple (>6) biopsies are taken in the clinical setting. In cardiovascular magnetic resonance (CMR), late gadolinium enhancement (LGE) depicts areas of affected myocardium in myocarditis or in other infiltrative cardiomyopathies. Thus, targeted biopsy under real-time CMR image guidance might reduce the problem of sampling error.

METHODS

Seven minipigs of the Goettingen strain underwent radiofrequency ablation in the left ventricle. At least two focal lesions were induced on the lateral wall in five and the apex in two animals. Each ablation lesion was created by two consecutive 30 sec ablations (max. 30 W, temperature 60-64 °C). Biopsies were taken immediately after lesion induction using a commercially available 7 F conventional bioptome under fluoroscopic guidance at the ablation site. Afterwards the animals underwent CMR and lesion visualization by LGE at 3T. The lesions were then targeted and biopsied under CMR-guidance using a MR-conditional bioptome guided by a steerable catheter. Interactive real-time (RT) visualization of the intervention on an in-room monitor was based on radial FLASH with nonlinear inverse reconstruction (NLINV) at a temporal resolution of 42 ms. All samples underwent a standard histological evaluation.

RESULTS

Radiofrequency ablation was successful in all animals. Fluoroscopy-guided biopsies were performed with a success rate of 6/6 minipigs - resulting in a nonlethal pericardial effusion in one animal. Visualization of radiofrequency lesions by CMR was successful in 7/7 minipig, i.e. at least one lesion was clearly visible. Localization and tracking of the catheters and the bioptome using interactive control of the imaging plane was achieved in 6/6 MP; however in the animal with a large pericardial effusion after EMB under fluoroscopy no further EMB was attempted for safety reasons. Biopsies under interactive RT-CMR guidance were successfully performed in 5/6 animals, in one animal the bioptome reached the lesion, however the forceps did not cut out a sample. Specimens obtained under CMR guidance contained part of the lesion in 6/15 (40%) myocardial specimens and in 4/5 (80%) animals in which samples were achieved. Conventional biopsies revealed ablation lesions in 4/17 (23.5%) specimens in 3/6 minipigs (50%).

CONCLUSION

Focal lesions induced by radiofrequency ablation in a minipig model are a useful tool for CMR-guided biopsy studies. In contrast to fluoroscopy, CMR provides excellent visualization of lesions. Interactive real-time CMR allows excellent passive tracking of the instruments and EMB provides significantly superior sampling accuracy compared to fluoroscopy-guided biopsies. Nonetheless, further improvements of MR-compatible bioptomes and guiding catheters are essential before applying this method in a clinical setting.

CD45 is a more sensitive marker than CD3 to diagnose lymphocytic myocarditis in the endomyocardium

To diagnose lymphocytic myocarditis (LM), immunohistopathological examination of endomyocardial biopsies (EMBs) is used with a cutoff value of at least 14 leukocytes per mm², composed of CD3- and CD68-positive cells. We hypothesized that a more common leukocyte marker, CD45, instead of CD3 could increase the diagnostic sensitivity. Hearts of mice with acute viral myocarditis (n = 9) and of controls (n = 7) and the EMB sampling area of the left ventricular posterior wall (LVPW) obtained from autopsied hearts of patients diagnosed with LM (n = 18) and controls (n = 6) were stained with anti-CD68, anti-CD3, and anti-CD45. When applying the threshold of at least 14 leukocytes per mm², 33% of the mice would be diagnosed with LM with the use of CD3⁺CD68 and 89% with the use of CD45⁺CD68. In the EMB sampling area of autopsied hearts, using the cutoff value of at least 14 leukocytes per mm², CD3⁺CD68 could only confirm 17% of the diagnosis of LM, whereas CD45⁺CD68 could confirm 50% of the LM cases. Moreover, we compared inflammation in the EMB sampling area of the LVPW to the remaining myocardium of the LVPW and observed a significant increase of CD45⁺CD68 cells per mm² in patients with LM. In conclusion, the use of the common leukocyte marker CD45 increases the sensitivity of the diagnosis of LM. Furthermore, the inflammatory infiltrate in the EMB sampling area is significantly increased compared with the remaining LVPW, indicating that the sampling area constitutes the highest chance for histological diagnosis of LM.

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.

Improvement of left ventricular systolic function in inflammatory cardiomyopathy: What plays a role?

AIMS

To compare the differences between patients with inflammatory cardiomyopathy (ICM) with and without improvement in left ventricular (LV) systolic function and to identify the relevant predictors of LV improvement.

PATIENTS AND METHODS

The study included 63 patients with biopsy-proven ICM and heart failure symptoms of at least NYHA II, symptom duration ≤ 6 months, LV ejection fraction (LVEF) ≤ 40% assessed by echocardiography and presence of >14 mononuclear leukocytes (LCA+ cells)/mm² in biopsy samples. Patients were evaluated at baseline and after 6 months.

RESULTS

In the group with LVEF improvement of ≥ 10% (I+ group, n = 41), LVEF increased from 24 ± 7% to 47 ± 8% (P < 0.001). In 22 patients (group I-), there was no or minimal LVEF increase (< 10%). In the I+ group, there were more LCA+ cells/mm² at baseline (25.1 ± 16.5 vs. 18.5 ± 4.4 cells/mm²; P = 0.032) and a more significant decrease in LCA+ cells in the follow-up (reduction of 13.6 ± 14.3 cells/mm² vs. 5.0 ± 7.7 cells/mm² in the I- group; P = 0.009). The univariate logistic regression showed a possible association of number of LCA+ cells, LV end-diastolic diameter and N-terminal fragment of pro-brain natriuretic peptide (NTproBNP) value with LVEF improvement. In the multivariate analysis, only NTproBNP at diagnosis was confirmed as an independent predictor of LVEF improvement (OR=1.2; 1.003 to 1.394; P = 0.046).

CONCLUSION

The LV systolic function improvement was observed in 65% of the patients. In these patients, the number of inflammatory cells at baseline was higher and decreased more but the higher baseline NTproBNP value was the only independent predictor of LVEF improvement.

Inflammatory Cardiomyopathy: A Current View on the Pathophysiology, Diagnosis, and Treatment

Inflammatory cardiomyopathy is defined as inflammation of the heart muscle associated with impaired function of the myocardium. In our region, its etiology is most often viral. Viral infection is a possible trigger of immune and autoimmune mechanisms which contributed to the damage of myocardial function. Myocarditis is considered the most common cause of dilated cardiomyopathy. Typical manifestation of this disease is heart failure, chest pain, or arrhythmias. The most important noninvasive diagnostic method is magnetic resonance imaging, but the gold standard of diagnostics is invasive examination, endomyocardial biopsy. In a significant proportion of cases with impaired left ventricular systolic function, recovery occurs spontaneously in several weeks and therefore it is appropriate to postpone critical therapeutic decisions about 3–6 months after start of the treatment. Therapy is based on standard heart failure treatment; immunosuppressive or antimicrobial treatment may be considered in some cases depending on the results of endomyocardial biopsy. If severe dysfunction of the left ventricle persists, device therapy may be needed.

Next-generation endomyocardial biopsy: the potential of confocal and super-resolution microscopy

Confocal laser scanning microscopy and super-resolution microscopy provide high-contrast and high-resolution fluorescent imaging, which has great potential to increase the diagnostic yield of endomyocardial biopsy (EMB). EMB is currently the gold standard for identification of cardiac allograft rejection, myocarditis, and infiltrative and storage diseases. However, standard analysis is dominated by low-contrast bright-field light and electron microscopy (EM); this lack of contrast makes quantification of pathological features difficult. For example, assessment of cardiac allograft rejection relies on subjective grading of H&E histology, which may lead to diagnostic variability between pathologists. This issue could be solved by utilising the high contrast provided by fluorescence methods such as confocal to quantitatively assess the degree of lymphocytic infiltrate. For infiltrative diseases such as amyloidosis, the nanometre resolution provided by EM can be diagnostic in identifying disease-causing fibrils. The recent advent of super-resolution imaging, particularly direct stochastic optical reconstruction microscopy (dSTORM), provides high-contrast imaging at resolution approaching that of EM. Moreover, dSTORM utilises conventional fluorescence dyes allowing for the same structures to be routinely imaged at the cellular scale and then at the nanoscale. The key benefit of these technologies is that the high contrast facilitates quantitative digital analysis and thereby provides a means to robustly assess critical pathological features. Ultimately, this technology has the ability to provide greater accuracy and precision to EMB assessment, which could result in better outcomes for patients.

Confocal Scanning Microscopy in Assessment of Cardiac Allograft Rejection--A Pilot Study

Cardiac allograft rejection is typically diagnosed on the basis of hematoxylin and eosin (H&E) histology of endomyocardial biopsies. This diagnosis is made based on the degree of immune cell infiltrate and associated myocyte damage. However, considerable variability in rejection grading between pathologists can occur. Confocal microscopy provides high contrast and high resolution imaging that has the potential to provide detailed views of pathological features of allograft rejection. In this pilot study we sought to determine if confocal microscopy could be used to detect features of cardiac rejection. This was achieved by collection of additional sample at 30 biopsy procedures from 15 heart transplant patients. Routine pathological grading of H&E histology identified 5 gradings of 0R, 21 gradings of 1R, and 3 gradings of 2R. From these gradings, 3 samples for 0R, 9 samples for 1R, and 3 samples for 2R were imaged by confocal microscopy. This was achieved by fluorescently labeling sections with DAPI, wheat germ agglutinin, and phalloidin, to visualize the cell nuclei, cell border and extracellular matrix, and muscle cell actin, respectively. Labeling with these fluorescent markers was of high contrast. However, we did note variability in DAPI and phalloidin labeling of tissue sections. Confocal imaging of these labels revealed the following features at high resolution: perivascular and/or interstitial infiltrate, myocyte damage, and Quilty lesions. In particular increased detail of damaged myocytes reveals distortion in myofilament organization that could be exploited to distinguish between 1R and 2R grades. In conclusion, confocal microscopy provided high contrast and resolution imaging of cardiac biopsies that could be explored further to aid assessment of cardiac allograft rejection.

Correlations of the changes in bioptic findings with echocardiographic, clinical and laboratory parameters in patients with inflammatory cardiomyopathy

Patients with myocarditis and left ventricular (LV) dysfunction may improve after standard heart failure therapy. This improvement seems to be related to retreat of myocardial inflammation. The aim of the present study was to assess changes in clinical, echocardiographic and some laboratory parameters and to correlate them with changes in the number of inflammatory infiltrating cells in endomyocardial biopsy (EMB) samples during the 6-month follow-up, and to define predictors of LV function improvement among baseline parameters. Forty patients with biopsy-proven myocarditis and impaired LV function (LV ejection fraction-LVEF <40 %) with heart failure symptoms ≤ 6 months were evaluated. Myocarditis was defined as the presence of >14 mononuclear leukocytes/mm(2) and/or >7 T-lymphocytes/mm(2) in the baseline EMB. The EMB, echocardiography and clinical evaluation were repeated after 6 months of standard heart failure therapy. LVEF improved on average from 25 ± 9 to 42 ± 12 % (p < 0.001); LV end-systolic volume and LV end-diastolic volume (LVEDV) decreased from 158 ± 61 to 111 ± 58 ml and from 211 ± 69 to 178 ± 63 ml (both p < 0.001). NYHA class decreased from 2.6 ± 0.5 to 1.6 ± 0.6 (p < 0.001) and NTproBNP from 2892 ± 3227 to 851 ± 1835 µg/ml (p < 0.001). A decrease in the number of infiltrating leukocytes (CD45+/LCA+) from 23 ± 15 to 13 ± 8 cells/mm(2) and in the number of infiltrating T lymphocytes (CD3+) from 7 ± 5 to 4 ± 3 cells/mm(2) (both p < 0.001) was observed. The decline in the number of infiltrating CD45+ cells significantly correlated with the change in LVEF (R = -0.43; p = 0.006), LVEDV (R = 0.39; p = 0.012), NYHA classification (R = 0.35; p = 0.025), and NTproBNP (R = 0.33; p = 0.045). The decrease in the number of CD3+ cells correlated with the change of systolic and diastolic diameters of the left ventricle (R = -0.33; p = 0.038 and R = -0.45; p = 0.003) and with the change in LVEDV (R = -0.43; p = 0.006). Tricuspid annular plane systolic excursion (TAPSE) (OR 0.61; p = 0.005) and early transmitral diastolic flow velocity (E wave) (OR 0.89; p = 0.002) were identified as predictors of LVEF improvement. Improvements in clinical status, LV function and NTproBNP levels correlated with decrease in the number of infiltrating inflammatory cells. TAPSE and E wave velocity were significant predictors of improvement in multivariate regression. Our observations suggest that contemporary guidelines-based therapy of heart failure is an effective treatment option in patients with recent onset biopsy-proven inflammatory cardiomyopathy.

Handling and interpretation of heart transplant biopsies

The biopsy material that is available for evaluation of the transplant heart is retrieved from an invasive biopsy procedure that is often small or suboptimal for evaluation. It is essential that the tissue is handled optimally from the time it is removed from the body to the time it is placed on the microscope stage to facilitate the best opportunity for an adequate diagnosis and to prevent the necessity for repeat costly and invasive procedures. Furthermore, the diagnostic information may be time sensitive for the treating clinician and mishandling the tissue or requiring a repeat biopsy will delay the start of treatment if the biopsy discloses actionable information. Herein we describe an optimized protocol for handling and interpreting heart transplant biopsies.