Necropsy diagnosis of myocarditis: a retrospective study using CD45RO immunohistochemistry

Visible and Near-Infrared hyperspectral imaging (HSI) can reliably quantify CD3 and CD45 positive inflammatory cells in myocarditis: Pilot study on formalin-fixed paraffin-embedded specimens from myocard obtained during autopsy

INTRODUCTION

To implement Hyperspectral Imaging (HSI) as a tool for quantifying inflammatory cells in tissue specimens by the example of myocarditis in a collective of forensic patients.

MATERIAL AND METHODS

44 consecutive patients with suspected myocardial inflammation at autopsy, diagnosed between 2013 and 2018 at the Institute of ForensicMedicine, Medical University of Innsbruck, were selected for this study. Using the IMEC SNAPSCAN camera, visible and near infrared hyperspectral images were collected from slides stained with CD3 and CD45 to assess quantity and spatial distribution of positive cells. Results were compared with visual assessment (VA) and conventional digital image analysis (DIA).

RESULTS

Finally, specimens of 40 patients were evaluated, of whom 36 patients (90%) suffered from myocarditis, two patients (5%) had suspected healing/healed myocarditis, and two did no have myocarditis (5%). The amount of CD3 and CD45 positive cells did not differ significantly between VA, HSI, and DIA (p^VA/HSI/DIA = 0.46 for CD3 and 0.81 for CD45). Coheńs Kappa showed a very high correlation between VA versus HSI, VA versus DIA, and HSI versus DIA for CD3 (Coheńs Kappa = 0.91, 1.00, and 0.91, respectively). For CD45 an almost as high correlation was seen for VA versus HSI and HSI versus DIA (Coheńs Kappa = 0.75 and 0.70) and VA versus DIA (Coheńs Kappa = 0.89).

CONCLUSION

HSI is a reliable and objective method to count inflammatory cells in tissue slides of suspected myocarditis. Implementation of HSI in digital pathology might further expand the possibility of a sophisticated method.

Characterization of heart macrophages in rhesus macaques as a model to study cardiovascular disease in humans

Rhesus macaques are physiologically similar to humans and, thus, have served as useful animal models of human diseases including cardiovascular disease. The purpose of this study was to characterize the distribution, composition, and phenotype of macrophages in heart tissues of very young (fetus: 0.5 years, n = 6), young adult (2-12 years, n = 12), and older adult (13-24 years, n = 9) rhesus macaques using histopathology and immunofluorescence microscopy. Results demonstrated that macrophages were uniformly distributed throughout the heart in animals of all age groups and were more prevalent than CD3-positve T-cells and CD20-positive B-cells. Macrophages comprised approximately 2% of heart tissue cells in the younger animals and increased to a mean of nearly 4% in the older adults. CD163-positive macrophages predominated over HAM56-positive and CD206-positive macrophages, and were detected at significantly higher percentage in the animals between 13 and 24 years of age, as well as in heart tissues exhibiting severe histopathology or inflammation in animals of all age groups. In vivo dextran labeling and retention indicated that approximately half of the macrophages were longer lived in healthy adult heart tissues and may comprise the tissue-resident population of macrophages. These results provide a basis for continued studies to examine the specific functional roles of macrophage subpopulations in heart tissues during homeostasis and in cardiovascular disease for then developing intervention strategies.

Acute myocarditis: multiparametric cardiac MR imaging

PURPOSE

To evaluate the diagnostic value of cardiac magnetic resonance (MR) imaging at 3 T in patients suspected of having acute myocarditis by using a multiparametric cardiac MR imaging approach including T1 relaxation time as an additional tool for tissue characterization.

MATERIALS AND METHODS

Ethics commission approval was obtained for this prospective study, and written informed consent was obtained from all subjects. Twenty four patients with acute myocarditis (mean age ± standard deviation, 34.7 years ± 15.1; 75% men) and 42 control subjects (mean age, 38.7 years ± 10.2; 64% men) were included. Cardiac MR imaging approaches included relative T2 short tau inversion-recovery signal intensity ratio (T2 ratio), early gadolinium enhancement ratio, late gadolinium enhancement, native T1 relaxation times, and extracellular volume fraction. Receiver operating characteristic analysis was performed to compare diagnostic performance. The reference standard was the clinical evidence for acute myocarditis.

RESULTS

Native T1 relaxation times were significantly longer in patients with acute myocarditis than in control subjects (1185.3 msec ± 49.3 vs 1089.1 msec ± 44.9, respectively; P < .001). Areas under the curve of native T1 relaxation times (0.94) were higher compared with those of other cardiac MR parameters (late gadolinium enhancement, 0.90; T2 ratio, 0.79; extracellular volume fraction, 0.71; early gadolinium enhancement ratio, 0.63; P = .390, .018, .002, and < .001, respectively). Sensitivity (92%), specificity (91%), and diagnostic accuracy (91%) for native T1 relaxation times (cutoff, 1140 msec) were equivalent compared with those of the established combined Lake Louise criteria (sensitivity, 92%; specificity, 80%; diagnostic accuracy, 85%).

CONCLUSION

Diagnostic performance with native T1 mapping was superior to that with T2 ratio and early gadolinium enhancement ratio, and specificity was higher with native T1 mapping than that with Lake Louise criteria. This study underlines the potential of native T1 relaxation times to complement current cardiac MR approaches in patients suspected of having acute myocarditis.

A case of asthma-complicated influenza myocarditis

A 36-year-old man with a history of asthma visited an outpatient clinic complaining of high fever and general fatigue, and was diagnosed as having influenza type A by influenza antigen test. Laboratory findings revealed mild inflammation, mild acidemia, and hypercapnea with radiologic infiltrations in the right lung, and remarkable wheezes in both lungs were heard on auscultation. He was diagnosed with asthma exacerbation and having influenza pneumonia, and was referred to us. Therapy was begun with oseltamivir for influenza infection and intravenous infusions of betamethasone and aminophylline with non-invasive pulmonary ventilation for asthma exacerbation and acute respiratory failure. Although he was weaned from mechanical ventilation and his general condition became good, electrocardiogram showed sinus bradycardia and negative T waves in V1-4 without any symptoms. Blood test and echocardiography showed almost normal findings except for slight elevation of LDH and AST. Influenza A antigen was already confirmed and he was diagnosed as having influenza myocarditis clinically. Although it is well known that influenza can cause asthma exacerbation and encephalopathy, influenza myocarditis is regarded as rare by physicians. In fact, the number of case reports about influenza myocarditis is few. Myocarditis may not appear to be serious, but could cause fatal arrhythmia and heart failure. All clinicians should be aware of the overall clinical picture and the possibility of severe complications of myocarditis caused by flu infection.

Diagnostic synergy of non-invasive cardiovascular magnetic resonance and invasive endomyocardial biopsy in troponin-positive patients without coronary artery disease

AIMS

Only few data are available regarding a direct comparison of both non-invasive CMR and invasive EMB with respect to conformity of procedure-derived diagnoses in the same patients. The aim of this study was to elucidate the diagnostic performance of non-invasive cardiovascular magnetic resonance imaging (CMR) and endomyocardial biopsy (EMB) in patients with troponin-I (TnI) positive acute chest pain in the absence of significant coronary artery disease (CAD).

METHODS AND RESULTS

One thousand one hundred and seventy-four consecutive patients who were admitted with TnI-positive acute chest pain between March 2004 and July 2007 underwent coronary angiography. In 1012 patients (86%), significant CAD (stenosis >50%) was detected as underlying reason for the acute chest pain. In 82 out of the remaining 162 patients without significant CAD, further workup was performed including both CMR and EMB. Cardiovascular magnetic resonance imaging alone enabled a diagnosis in 66/82 (80%) and EMB alone in 72/82 (88%) patients (P = 0.31). Myocarditis was the most frequent diagnosis by both CMR and EMB in this cohort and was detected with a higher frequency by EMB (58 vs. 81%; P < 0.001). With the combined approach comprising CMR and EMB, a final diagnosis could be established applying the 'Believe-The-Positive-Rule' in 78/82 patients (95%). This combined approach turned out to yield more diagnoses than either CMR (P < 0.001) or EMB (P = 0.03) as single techniques, respectively. Comparison of diagnostic CMR procedures with the corresponding diagnostic EMBs demonstrated a substantial match of diagnoses (kappa = 0.70).

CONCLUSION

Cardiovascular magnetic resonance imaging and EMB have good diagnostic performances as single techniques in patients with TnI-positive acute chest pain in the absence of CAD. The combined application of CMR and EMB yields a considerable diagnostic synergy by overcoming some limitations of CMR and EMB as individually applied techniques.

High prevalence of chronic myocarditis in dilated cardiomyopathy referred for left ventriculoplasty: expression of tenascin C as a possible marker for inflammation

The objectives of this study were to analyze the incidence of chronic myocarditis in dilated cardiomyopathy and to evaluate the diagnostic value of tenascin C for assessing inflammatory activity in the resected myocardium. Dilated cardiomyopathy patients with chronic myocarditis have a poor clinical outcome despite recent advances in medical treatments. Therefore, a precise diagnosis of inflammatory activity is critical to ensuring appropriate therapy. Tenascin C is an extracellular matrix glycoprotein that plays an important role in tissue remodeling in various heart diseases. Myocardial samples obtained during left ventriculoplasty from 64 patients (50 +/- 13 years, 56 men and 8 women) with dilated cardiomyopathy were examined by immunostaining for tenascin C. Histologic diagnosis was based on the Dallas criteria modified by the International Society and Federation of Cardiology task force. Nine cases (14%) had active myocarditis, 21 (33%) had borderline myocarditis, and 34 (53%) had no myocarditis. Intense tenascin C expression was observed at the site of active inflammation, with abundant cell accumulation, and in organized granulation tissue during the resolving phase but not in scar tissue during the healing phase. The ratio of tenascin C-positive area to the whole myocardium in the active and borderline myocarditis groups was significantly greater than that in the noninflammatory group. These findings suggest a high prevalence of chronic myocarditis in dilated cardiomyopathy patients and that tenascin C may prove to be a useful marker for distinguishing inflammatory cardiomyopathy from other types of dilated cardiomyopathy.

Presentation, Patterns of Myocardial Damage, and Clinical Course of Viral Myocarditis

BACKGROUND

Enteroviruses and adenoviruses have been considered the most common causes of viral myocarditis, but parvovirus B19 (PVB19) and human herpesvirus 6 (HHV6) are increasingly found in endomyocardial biopsy samples.

METHODS AND RESULTS

Consequently, our aim was to evaluate the prevalence and clinical presentation of cardiac PVB19 and/or HHV6 infection in a cohort of myocarditis patients and to follow its clinical course. In addition, we sought to demonstrate patterns of myocardial damage and to determine predictors for chronic heart failure. Our study design consisted of a cardiovascular magnetic resonance protocol as well as endomyocardial biopsies in the myocardial region affected as indicated by cardiovascular magnetic resonance. One hundred twenty-eight patients were enrolled by clinical criteria. In the group of myocarditis patients (n=87), PVB19 (n=49), HHV6 (n=16), and combined PVB19/HHV6 infections (n=15) were detected most frequently. The remaining patients were diagnosed with healing myocarditis (n=15) or did not have myocarditis (n=26). Patients with PVB19 presented in a manner similar to that of myocardial infarction; most had typical subepicardial late gadolinium enhancement in the lateral wall and recovered within months. Conversely, patients with HHV6 and especially with HHV6/PVB19 myocarditis presented with new onset of heart failure, had septal late gadolinium enhancement, and frequently progressed toward chronic heart failure.

CONCLUSIONS

Our data indicate that PVB19 and HHV6 are the most important causes for viral myocarditis in Germany and that the clinical presentation is related to the type of virus. Furthermore, clinical presentation, type of virus, and pattern of myocardial damage are related to the clinical course.

Endomyocardial biopsy for non-transplant-related disorders

Endomyocardial biopsy (EMB) remains the "gold standard" for diagnosing rejection after cardiac transplantation. In addition, it has value in monitoring patients during treatment with doxorubicin. It also is important in the setting of acute-onset heart failure for the diagnosis of myocarditis, particularly giant cell myocarditis because earlier transplantation usually is undertaken in patients with giant cell morphologic features. EMB has a role in the unexplained cardiomyoapthy for excluding specific disease processes that might lead to similar morphofunctional changes but might be reversible or a contraindication for transplantation. This review focuses on the growing number of diseases that can be diagnosed by EMB in adult and pediatric age groups.

Fulminant myocarditis demonstrating uncommon morphology--a report of two autopsy cases

Two autopsy cases of fulminant myocarditis demonstrating uncommon morphology were studied. Subjects included two male patients: a 42-year-old (case 1) and a 39-year-old (case 2). Both cases had fever, chest or epigastric pain, electrocardiographic abnormalities, prominent elevation of serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactic dehydrogenase and creatine phosphokinase. They were treated with intra-aortic balloon pumping and percutaneous cardiopulmonary support, and they died at 3 days and 4 days after admission (total course of 10 days and 9 days), respectively. Case 1 showed focal necrosis, severe myocardial dystrophic calcification positive for Kossa stain, inflammatory edema, lymphocyte and macrophage infiltration and extravasation of erythrocytes. Case 2 showed acute inflammation and severe myocardial necrosis with neutrophilic abscess, lymphocyte and macrophage infiltration, cell debris and purulent exudate. Calcified, degenerative and necrotic cardiac myocytes and macrophages were reacted with anti-Enterovirus antibody (clone 5-D8/1), which recognizes an epitope on the VP1 peptide of most Coxsackievirus, echovirus, poliovirus and enterovirus strains. Therefore, the present two cases may be compatible with fulminant enterovirus-associated myocarditis. Using reverse transcriptase-semi-nested polymerase chain reaction, picornaviral RNA was detected in the amplified products extracted from the paraffin-embedded myocardial sample of case 1 but not in case 2.

Cardiac disease in myasthenia gravis: a literature review

Patients with myasthenia gravis might develop various cardiac disorders, yet a causal relationship remains unestablished. Because causes of sudden death in this population have not been ascertained, further attention to possible cardiac disease in this population is warranted. We summarize the current literature and describe the possible etiologies and implications of cardiac disease in myasthenics.