Idiopathic giant cell myocarditis and cardiac sarcoidosis

Imaging of Cardiac Sarcoidosis: An Update and Future Aspects

Cardiac sarcoidosis (CS), an increasingly recognized disease of unknown etiology, is associated with significant morbidity and mortality. Given the limited diagnostic yield of traditional endomyocardial biopsy (EMB), there is increasing reliance on multimodality cardiovascular imaging in the diagnosis and management of CS, with EMB being largely supplanted by the use of 18F-fluorodeoxyglucose (FDG-PET) and cardiac magnetic resonance imaging (CMR). This article aims to provide a comprehensive review of imaging modalities currently utilized in the screening, diagnosis, and monitoring of CS, while highlighting the latest developments in each area.

At the heart of inflammation: Unravelling cardiac resident macrophage biology

Cardiovascular disease remains one of the leading causes of death globally. Recent advancements in sequencing technologies have led to the identification of a unique population of macrophages within the heart, termed cardiac resident macrophages (CRMs), which exhibit self-renewal capabilities and play crucial roles in regulating cardiac homeostasis, inflammation, as well as injury and repair processes. This literature review aims to elucidate the origin and phenotypic characteristics of CRMs, comprehensively outline their contributions to cardiac homeostasis and further summarize their functional roles and molecular mechanisms implicated in the onset and progression of cardiovascular diseases. These insights are poised to pave the way for novel therapeutic strategies centred on targeted interventions based on the distinctive properties of resident macrophages.

Autoimmune Myocarditis, Old Dogs and New Tricks

Autoimmunity significantly contributes to the pathogenesis of myocarditis, underscored by its increased frequency in autoimmune diseases such as systemic lupus erythematosus and polymyositis. Even in cases of myocarditis caused by viral infections, dysregulated immune responses contribute to pathogenesis. However, whether triggered by existing autoimmune conditions or viral infections, the precise antigens and immunologic pathways driving myocarditis remain incompletely understood. The emergence of myocarditis associated with immune checkpoint inhibitor therapy, commonly used for treating cancer, has afforded an opportunity to understand autoimmune mechanisms in myocarditis, with autoreactive T cells specific for cardiac myosin playing a pivotal role. Despite their self-antigen recognition, cardiac myosin-specific T cells can be present in healthy individuals due to bypassing the thymic selection stage. In recent studies, novel modalities in suppressing the activity of pathogenic T cells including cardiac myosin-specific T cells have proven effective in treating autoimmune myocarditis. This review offers an overview of the current understanding of heart antigens, autoantibodies, and immune cells as the autoimmune mechanisms underlying various forms of myocarditis, along with the latest updates on clinical management and prospects for future research.

Two case reports of fulminant giant cell myocarditis treated with rabbit anti-thymocyte globulin

Background

Giant cell myocarditis (GCM) is an inflammatory form of acute heart failure with high rates of cardiac transplantation or death. Standard acute treatment includes multi-drug immunosuppressive regimens. There is a small but growing number of case reports utilizing rabbit anti-thymocyte globulin in severe cases.

Case summary

Two cases are presented with similar presentations and clinical courses. Both are middle-aged patients with no significant past medical history, who presented with new acute decompensated heart failure that quickly progressed to cardiogenic shock requiring inotropic and mechanical circulatory support. Both underwent endomyocardial biopsies that diagnosed GCM. Both were treated with a multi-agent immunosuppressive regimen, notably including rabbit anti-thymocyte globulin, with subsequent resolution of shock and recovery of left ventricular ejection fraction. Both remain transplant-free and without ventricular arrhythmias at 7 months and 26 months, respectively.

Discussion

In aggregate, these cases are typical of GCM. They add to growing observational data that upfront rabbit anti-thymocyte globulin may reduce morbidity and mortality in GCM, including potentially preventing the need for complex interventions like orthotopic heart transplantation.

Mechanical Circulatory Support Systems in Fulminant Myocarditis: Recent Advances and Outlook

Background: Fulminant myocarditis (FM) constitutes a severe and life-threatening form of acute cardiac injury associated with cardiogenic shock. The condition is characterised by rapidly progressing myocardial inflammation, leading to significant impairment of cardiac function. Due to the acute and severe nature of the disease, affected patients require urgent medical attention to mitigate adverse outcomes. Besides symptom-oriented treatment in specialised intensive care units (ICUs), the necessity for temporary mechanical cardiac support (MCS) may arise. Numerous patients depend on these treatment methods as a bridge to recovery or heart transplantation, while, in certain situations, permanent MCS systems can also be utilised as a long-term treatment option. Methods: This review consolidates the existing evidence concerning the currently available MCS options. Notably, data on venoarterial extracorporeal membrane oxygenation (VA-ECMO), microaxial flow pump, and ventricular assist device (VAD) implantation are highlighted within the landscape of FM. Results: Indications for the use of MCS, strategies for ventricular unloading, and suggested weaning approaches are assessed and systematically reviewed. Conclusions: Besides general recommendations, emphasis is put on the differences in underlying pathomechanisms in FM. Focusing on specific aetiologies, such as lymphocytic-, giant cell-, eosinophilic-, and COVID-19-associated myocarditis, this review delineates the indications and efficacy of MCS strategies in this context.

Advancing Precision Medicine in Myocarditis: Current Status and Future Perspectives in Endomyocardial Biopsy-Based Diagnostics and Therapeutic Approaches

The diagnosis and specific and causal treatment of myocarditis and inflammatory cardiomyopathy remain a major clinical challenge. Despite the rapid development of new imaging techniques, endomyocardial biopsies remain the gold standard for accurate diagnosis of inflammatory myocardial disease. With the introduction and continued development of immunohistochemical inflammation diagnostics in combination with viral nucleic acid testing, myocarditis diagnostics have improved significantly since their introduction. Together with new technologies such as miRNA and gene expression profiling, quantification of specific immune cell markers, and determination of viral activity, diagnostic accuracy and patient prognosis will continue to improve in the future. In this review, we summarize the current knowledge on the pathogenesis and diagnosis of myocarditis and inflammatory cardiomyopathies and highlight future perspectives for more in-depth and specialized biopsy diagnostics and precision, personalized medicine approaches.

Inhibition of NETosis via PAD4 alleviated inflammation in giant cell myocarditis

Giant cell myocarditis (GCM) is a rare, usually rapidly progressive, and potentially fatal disease. Detailed inflammatory responses remain unknown, in particular the formation of multinucleate giant cells. We performed single-cell RNA sequencing analysis on 15,714 Cd45+ cells extracted from the hearts of GCM rats and normal rats. NETosis has been found to contribute to the GCM process. An inhibitor of NETosis, GSK484, alleviated GCM inflammation in vivo. MPO (a marker of neutrophils) and H3cit (a marker of NETosis) were expressed at higher levels in patients with GCM than in patients with DCM and healthy controls. Imaging mass cytometry analysis revealed that immune cell types within multinucleate giant cells included CD4+ T cells, CD8+ T cells, neutrophils, and macrophages but not B cells. We elucidated the role of NETosis in GCM pathogenesis, which may serve as a potential therapeutic target in the clinic.

Atrial giant cell myocarditis with preserved left ventricular function: a case report and literature review

Giant cell myocarditis (GCM) is a rare and fatal inflammatory disorder induced by T-lymphocytes, typically affecting young adults. Generally, this disease presents with a rapidly progressive course and a very poor prognosis. In recent years, atrial GCM (aGCM) has been recognized as a clinicopathological entity distinct from classical GCM. As described by retrievable case reports, although its histopathological manifestations are highly similar to those of classical GCM, this entity is characterized by preserved left ventricular function and atrial arrhythmias, without ventricular arrhythmias. aGCM tends to show benign disease progression with a better clinical prognosis compared with the rapid course and poor prognosis of vGCM. We report a patient with aGCM with a history of renal abscess whose persistent myocardial injury considered to be associated with a history of renal abscess. Infection could be a potential trigger for the development of aGCM in this patient. An extensive literature review was also performed and the following three aspects were summarized: (1) Epidemiology and histopathological characteristics of aGCM; (2) The role of imaging in the evaluation of aGCM; (3) Diagnostic points and therapeutic decisions in aGCM.

Immunomodulatory Therapy for Giant Cell Myocarditis: A Narrative Review

Giant cell myocarditis (GCM) is a rare, often rapidly progressive, and potentially fatal disease because of myocardium inflammation due to the infiltration of giant cells triggered by infectious as well as non-infectious etiologies. Several studies have reported that GCM can occur in patients of all ages but is more commonly found in adults. It is relatively more common among African American and Hispanic patients than in the White population. Early diagnosis and treatment are critical. Electrocardiogram (EKG), complete blood count, erythrocyte sedimentation rate, C-reactive protein, and cardiac biomarkers such as troponin and brain natriuretic peptide (BNP), echocardiogram, cardiac magnetic resonance imaging (MRI), myocardial biopsy, and myocardial gene profiling are useful diagnostic tools. Current research has identified several potential biomarkers for GCM, including myocarditis-associated immune cells, cytokines, and other chemicals. The standard of care for GCM includes aggressive immunosuppressive therapy with corticosteroids and immunomodulatory agents like rituximab, cyclosporine, and infliximab, which have shown promising results in GCM by balancing the immune system and preventing the attack on healthy tissues, resulting in the reduction of inflammation, promotion of healing, and decreasing the necessity for cardiac transplantation. Without immunosuppression, the chance of mortality or cardiac surgery was 100%. Multiple studies have revealed that a treatment combination of corticosteroids and immunomodulatory agents is superior to corticosteroids alone. Combination therapy significantly increased transplant-free survival (TFS) and decreased the likelihood of heart transplantation, hence improving overall survival. It is important to balance the benefits of immunosuppression with its potentially adverse effects. In conclusion, immunomodulatory therapy adds significant long-term survival benefits to GCM.

Echocardiography in inflammatory heart disease: A comparison of giant cell myocarditis, cardiac sarcoidosis, and acute non-fulminant myocarditis

Background

Giant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are, in contrast to acute non-fulminant myocarditis (ANFM), rare inflammatory diseases of the myocardium with poor prognosis. Although echocardiography is the first-line diagnostic tool in these patients, their echocardiographic appearance has so far not been systematically studied.

Methods

We assessed a total of 71 patients with endomyocardial biopsy-proven GCM (n = 21), and CS (n = 25), as well as magnetic resonance-verified ANFM (n = 25). All echocardiographic examinations, performed upon clinical presentation, were reanalysed according to current guidelines including a detailed assessment of right ventricular (RV) dysfunction.

Results

In comparison with ANFM, patients with either GCM or CS were older (mean age (±SD) 55 ± 12 or 53 ± 8 vs 25 ± 8 years), more often of female gender (52% or 24% vs 8%), had more severe clinical symptoms and higher natriuretic peptide levels. For both GCM and CS, echocardiography revealed more frequently signs of left ventricular (LV) dysfunction in form of a reduced ejection fraction (p < 0.001), decreased cardiac index (p < 0.001) and lower global longitudinal strain (p < 0.001) in contrast to ANFM. The most prominent increase in LV end-diastolic volume index was observed in CS. In addition, RV dysfunction was more frequently found in both GCM and CS than in ANFM (p = 0.042).

Conclusions

Both GCM and CS have an echocardiographic and clinical appearance that is distinct from ANFM. However, the method cannot further differentiate between the two rare entities. Consequently, echocardiography can strengthen the initial clinical suspicion of a more severe form of myocarditis, thus warranting a more rigorous clinical work-up.

Fulminant Myocarditis: When One Size Does Not Fit All - A Critical Review of the Literature

Fulminant myocarditis, rather than being a distinct form of myocarditis, is instead a peculiar clinical presentation of the disease. The definition of fulminant myocarditis has varied greatly in the last 20 years, leading to conflicting reports on prognosis and treatment strategies, mainly because of varied inclusion criteria in different studies. The main conclusion of this review is that fulminant myocarditis may be due to different histotypes and aetiologies that can be diagnosed only by endomyocardial biopsy and managed by aetiology-directed treatment. This life-threatening presentation requires rapid, targeted management both in the short term (mechanical circulatory support, inotropic and antiarrhythmic treatment and endomyocardial biopsy) and in the long term (including prolonged follow-up). Fulminant presentation has also recently been identified as a risk factor for worsened prognosis, even long after the resolution of the acute phase of myocarditis.

Cardiac magnetic resonance in giant cell myocarditis: a matched comparison with cardiac sarcoidosis

AIMS

Giant cell myocarditis (GCM) is an inflammatory cardiomyopathy akin to cardiac sarcoidosis (CS). We decided to study the findings of GCM on cardiac magnetic resonance (CMR) imaging and to compare GCM with CS.

METHODS AND RESULTS

CMR studies of 18 GCM patients were analyzed and compared with 18 CS controls matched for age, sex, left ventricular (LV) ejection fraction and presenting cardiac manifestations. The analysts were blinded to clinical data. On admission, the duration of symptoms (median) was 0.2 months in GCM vs. 2.4 months in CS (P = 0.002), cardiac troponin T was elevated (>50 ng/L) in 16/17 patients with GCM and in 2/16 with CS (P < 0.001), their respective median plasma B-type natriuretic propeptides measuring 4488 ng/L and 1223 ng/L (P = 0.011). On CMR imaging, LV diastolic volume was smaller in GCM (177 ± 32 mL vs. 211 ± 58 mL, P = 0.014) without other volumetric or wall thickness measurements differing between the groups. Every GCM patient had multifocal late gadolinium enhancement (LGE) in a distribution indistinguishable from CS both longitudinally, circumferentially, and radially across the LV segments. LGE mass averaged 17.4 ± 6.3% of LV mass in GCM vs 25.0 ± 13.4% in CS (P = 0.037). Involvement of insertion points extending across the septum into the right ventricular wall, the "hook sign" of CS, was present in 53% of GCM and 50% of CS.

CONCLUSION

In GCM, CMR findings are qualitatively indistinguishable from CS despite myocardial inflammation being clinically more acute and injurious. When matched for LV dysfunction and presenting features, LV size and LGE mass are smaller in GCM.

Comparisons between biopsy-proven versus clinically diagnosed cardiac sarcoidosis

OBJECTIVES

Diagnosis of cardiac sarcoidosis (CS) without histological evidence remains controversial. This study aimed to compare characteristics and outcomes of histologically proven versus clinically diagnosed cases of CS, which were adjudicated using Heart Rhythm Society or Japanese Circulation Society criteria.

METHODS

A total of 512 patients with CS (age: 62±11 years, female: 64.3%) enrolled in the multicentre registry were studied. Histologically confirmed patients were classified as 'biopsy-proven CS', while those with the presence of strongly suggestive clinical findings of CS without histological evidence were classified as 'clinical CS'. Primary outcome was a composite of all-cause death, heart failure hospitalisation and ventricular arrhythmia event.

RESULTS

In total, 314 patients (61.3%) were classified as biopsy-proven CS, while 198 (38.7%) were classified as clinical CS. Patients classified under clinical CS were associated with higher prevalence of left ventricular dysfunction, septal thinning, and positive findings in fluorodeoxyglucose-positron emission tomography or Gallium scintigraphy than those under biopsy-proven CS. During median follow-up of 43.7 (23.3-77.3) months, risk of primary outcome was comparable between the groups (adjusted HR: 1.24, 95% CI: 0.88 to 1.75, p=0.22). Similarly, the risks of primary outcome were comparable between patients with clinical isolated CS who did not have other organ/tissue involvement, and biopsy-proven isolated CS (adjusted HR: 1.23, 95% CI: 0.56 to 2.70, p=0.61).

CONCLUSIONS

A substantial number of patients were diagnosed with clinical CS without confirmatory biopsy. Considering the worse clinical outcomes irrespective of the histological evidence, the diagnosis of clinical CS is justifiable if imaging findings suggestive of CS are observed.

Paediatric giant cell myocarditis: a case report

A previously healthy 15-year-old teenage boy was admitted for fever and heart failure. Myocarditis was suspected, and endomyocardial biopsy revealed giant cell myocarditis. Immunosuppressive treatment was initiated, with excellent response. A plausible link to previous leptospirosis was identified. At 18-month follow-up, left ventricular function is normal. Only one other reported case of paediatric giant cell myocarditis had such a favourable outcome.

Diagnosis, management, and outcome of cardiac sarcoidosis and giant cell myocarditis: a Swedish single center experience

Background

Cardiac sarcoidosis (CS) and giant cell myocarditis (GCM) are rare diseases that share some similarities, but also display different clinical and histopathological features. We aimed to compare the demographics, clinical presentation, and outcome of patients diagnosed with CS or GCM.

Method

We compared the clinical data and outcome of all adult patients with CS (n = 71) or GCM (n = 21) diagnosed at our center between 1991 and 2020.

Results

The median (interquartile range) follow-up time for patients with CS and GCM was 33.5 [6.5–60.9] and 2.98 [0.6–40.9] months, respectively. In the entire cohort, heart failure (HF) was the most common presenting manifestation (31%), followed by ventricular arrhythmias (25%). At presentation, a left ventricular ejection fraction of < 50% was found in 54% of the CS compared to 86% of the GCM patients (P = 0.014), while corresponding proportions for right ventricular dysfunction were 24% and 52% (P = 0.026), respectively. Advanced HF (NYHA ≥ IIIB) was less common in CS (31%) than in GCM (76%). CS patients displayed significantly lower circulating levels of natriuretic peptides (P < 0.001) and troponins (P = 0.014). Eighteen percent of patients with CS included in the survival analysis reached the composite endpoint of death or heart transplantation (HTx) compared to 68% of patients with GCM (P < 0.001).

Conclusion

GCM has a more fulminant clinical course than CS with severe biventricular failure, higher levels of circulating biomarkers and an increased need for HTx. The histopathologic diagnosis remained key determinant even after adjustment for markers of cardiac dysfunction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02639-0.

Giant Cell Myocarditis in Children: Elusive Giant Cells Might Not Be the Only Clue

Giant cell myocarditis (GCM) is a form of fulminant myocarditis that is rapidly progressive and frequently lethal even in children. Over the course of 20 years, a definitive histopathologic diagnosis of GCM has been made at our institution in only two pediatric patients, and in neither instance was the diagnosis of GCM rendered on initial cardiac biopsy. We present the two patients and highlight the similarities in their clinical presentation and their challenging and inconclusive- albeit histologically similar- initial cardiac biopsy findings.

Fulminant myocarditis in adults: a narrative review

Fulminant myocarditis (FM) is an uncommon syndrome characterized by sudden and severe hemodynamic compromise secondary to acute myocardial inflammation, often presenting as profound cardiogenic shock, life-threatening ventricular arrhythmias and/or electrical storm. FM may be refractory to conventional therapies and require mechanical circulatory support (MCS). The immune system has been recognized as playing a pivotal role in the pathophysiology of myocarditis, leading to an increased focus on immunosuppressive treatment strategies. Recent data have highlighted not only the fact that FM has significantly worse outcomes than non-FM, but that prognosis and management strategies of FM are heavily dependent on histological subtype, placing greater emphasis on the role of endomyocardial biopsy in diagnosis. The impact of subtype on severity and prognosis will likewise influence how aggressively the myocarditis is managed, including whether MCS is warranted. Many patients with refractory cardiogenic shock secondary to FM end up requiring MCS, with venoarterial extracorporeal membrane oxygenation demonstrating favorable survival rates, particularly when initiated prior to the development of multiorgan failure. Among the challenges facing the field are the need to more precisely identify immunopathophysiological pathways in order to develop targeted therapies, and the need to better optimize the timing and management of MCS to minimize complications and maximize outcomes.

PET Imaging in Cardiac Sarcoidosis: A Narrative Review with Focus on Novel PET Tracers

Sarcoidosis is a multi-system inflammatory disease characterized by the development of inflammation and noncaseating granulomas that can involve nearly every organ system, with a predilection for the pulmonary system. Cardiac involvement of sarcoidosis (CS) occurs in up to 70% of cases, and accounts for a significant share of sarcoid-related mortality. The clinical presentation of CS can range from absence of symptoms to conduction abnormalities, heart failure, arrhythmias, valvular disease, and sudden cardiac death. Given the significant morbidity and mortality associated with CS, timely diagnosis is important. Traditional imaging modalities and histologic evaluation by endomyocardial biopsy often provide a low diagnostic yield. Cardiac positron emission tomography (PET) has emerged as a leading advanced imaging modality for the diagnosis and management of CS. This review article will summarize several aspects of the current use of PET in CS, including indications for use, patient preparation, image acquisition and interpretation, diagnostic and prognostic performance, and evaluation of treatment response. Additionally, this review will discuss novel PET radiotracers currently under study or of potential interest in CS.

Immune Checkpoint Inhibitors Mediated Lymphocytic and Giant Cell Myocarditis: Uncovering Etiological Mechanisms

The advent of immune checkpoint inhibitors (ICIs) has revolutionized the field of oncology, but these are associated with immune related adverse events. One such adverse event, is myocarditis, which has limited the continued immunosuppressive treatment options in patients afflicted by the disease. Pre-clinical and clinical data have found that specific ICI targets and precipitate distinct myocardial infiltrates, consistent with lymphocytic or giant cell myocarditis. Specifically, it has been reported that CTLA-4 inhibition preferentially results in giant cell myocarditis with a predominately CD4+ T cell infiltrate and PD-1 inhibition leads to lymphocytic myocarditis, with a predominately CD8+ T cell infiltrate. Our manuscript discusses the latest literature surrounding ICI pathways and targets, while detailing proposed mechanisms behind ICI mediated myocarditis.

Zwei Fälle kardialer Sarkoidose als Ursache des plötzlichen Herztodes

Eine der primären Aufgaben der Rechtsmedizin ist die Aufklärung unerwarteter Todesfälle. Speziell das Erkennen seltener Todesursachen setzt ein fundiertes Wissen um die typischen makromorphologischen Befunde sowie das Einleiten und die Interpretation entsprechend geeigneter Ergänzungsuntersuchungen, etwa histologischer Verfahren, voraus. Wichtige Differenzialdiagnosen müssen bekannt sein, damit die Todesursache mit vertretbarem diagnostischem Aufwand festgestellt werden kann.

In der vorliegenden Arbeit werden charakteristische makroskopische und mikroskopische Befunde der kardialen Sarkoidose (oder granulomatösen Myokarditis) und deren Abgrenzung zur Riesenzellmyokarditis anhand von 2 Fällen demonstriert. In beiden Fällen gab der plötzliche Tod einer erwachsenen Person mittleren Alters Anlass zu einer gerichtlichen Obduktion, die jeweils zur Diagnose einer kardialen Sarkoidose führte. Die unterschiedlichen Krankheitsverläufe und Befunde werden unter Berücksichtigung einschlägiger wissenschaftlicher Literatur diskutiert. Durch eine sorgfältige Erhebung der Vorgeschichte und der makromorphologischen Befunde kann die Verdachtsdiagnose einer kardialen Sarkoidose unmittelbar nach der Obduktion geäußert und durch histopathologische Untersuchungen bestätigt werden. Es wird deutlich, dass eine interdisziplinäre Fallarbeit bei seltenen Erkrankungen wie der kardialen Sarkoidose eine schnelle Diagnose ermöglicht.

Effect of Corticosteroid Therapy in Patients With Cardiac Sarcoidosis on Frequency of Venous Thromboembolism

Sarcoidosis is a multisystem inflammatory condition with occasional cardiac involvement (CS), which may be associated with risk of venous thromboembolism (VTE). As data on VTE in CS are sparse and corticosteroid therapy has not been previously examined, we aim to determine the association between CS, corticosteroid treatment for CS, and VTE. Patients referred to our institution with concern for sarcoidosis and underwent a positron emission tomography (PET) scan were retrospectively assessed. Chi-squared and multivariate regression analyses were conducted to determine the association between a diagnosis of sarcoidosis, CS, corticosteroid use, and VTE events. Six hundred and forty nine patients were split into 3 categories: 235 with no sarcoidosis (NS), 91 with extra-cardiac sarcoidosis only (ECS), and 323 with CS (isolated CS and/or CS with extra cardiac sarcoid). Thirty nine CS, 7 ECS, and 9 NS patients developed PE while 44 CS, 3 ECS, and 18 NS patients developed DVT. On multivariate regression, neither CS nor ECS was an independent risk factor for VTE (p >0.05) but corticosteroid use was independently associated with VTE (HR 3.06, p = 0.007 for PE, HR 6.21, p <0.0001 for DVT). On logistic regression analysis, corticosteroid dose was found to be independently associated with both PE (p = 0.001) and DVT (p = 0.007). Optimal threshold for defining VTE risk with corticosteroid therapy was a prednisone-equivalent dose of 17.5 mg. In conclusion, contrary to previous studies, this current study found that neither sarcoidosis nor CS is an independent risk factor for VTE. Rather, corticosteroid therapy was associated with an increased risk of VTE.

The Role of Multimodality Imaging in Cardiac Sarcoidosis

The etiology and the progression of sarcoidosis remain unknown. However, cardiac sarcoidosis (CS) is significantly associated with a poor prognosis due to the associated congestive heart failure, arrhythmias (such as an advanced atrioventricular block), and ventricular tachyarrhythmia. Novel imaging modalities are now available to detect CS lesions secondary to active inflammation, granuloma formation, and fibrotic changes. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and cardiac magnetic resonance imaging (CMR) play essential roles in diagnosing and monitoring patients with confirmed or suspected CS. The following focused review will highlight the emerging role of non-invasive cardiac imaging techniques, including FDG PET/CT and CMR.

Arrhythmia in Cardiac Sarcoidosis

Cardiac sarcoidosis (CS) is a complex disease that can manifest as a diverse array of arrhythmias. CS patients may be at higher risk for sudden cardiac death (SCD), and, in some cases, SCD may be the first presenting symptom of the underlying disease. As such, identification, risk stratification, and management of CS-related arrhythmia are crucial in the care of these patients. Left untreated, CS carries significant arrhythmogenic morbidity and mortality. Cardiac manifestations of CS are a consequence of an inflammatory process resulting in the myocardial deposition of noncaseating granulomas. Endomyocardial biopsy remains the gold standard for diagnosis; however, biopsy yield is limited by the patchy distribution of the granulomas. As such, recent guidelines have improved clinical diagnostic pathways relying on advanced cardiac imaging to help in the diagnosis of CS. To date, corticosteroids are the best studied agent to treat CS but are associated with significant risks and limited benefits. Implantable cardioverter-defibrillators have an important role in SCD risk reduction. Catheter ablation in conjunction with antiarrhythmics seems to reduce ventricular arrhythmia burden. However, the appropriate selection of these patients is crucial as ablation is likely more helpful in the setting of a myocardial scar substrate versus arrhythmia driven by active inflammation. Further studies investigating CS pathophysiology, the pathway to diagnosis, arrhythmogenic manifestations, and SCD risk stratification will be crucial to reduce the high morbidity and mortality of this disease.

Identification of a novel presumed cardiac sarcoidosis category for patients at high risk of disease

BACKGROUND

Histologic evidence is required for a definitive diagnosis of cardiac sarcoidosis (CS) by published guidelines; however, the sporadic nature of the disease may produce false negative biopsy results, causing CS to be underdiagnosed. We sought to establish a clinical category of CS absent histologic findings.

METHODS

Patients evaluated for CS were stratified into 3 groups: probable CS and definite CS based on Heart Rhythm Society (HRS) criteria and presumed CS, ie, patients without any histologic evidence of sarcoidosis, but with unexplained high-grade atrioventricular block or ventricular arrhythmia and findings suggestive of CS on either cardiac magnetic resonance imaging or positron emission tomography. The primary end point was hospitalization-free and overall survival at 10 years.

RESULTS

A total of 383 patients were included in the study: 59, definite CS; 223, probable CS; and 101, presumed CS (62, isolated CS and 39, systemic CS). Compared with patients meeting HRS criteria for CS, patients with presumed CS had lower odds of New York Heart Association class III or IV symptoms (odds ratio [OR], 0.44 [95% CI, 0.23-0.83]; P = .01) but greater odds of previous ventricular tachycardia (OR, 2.4 [95% CI, 1.4-4.0]; P = .001) or history of resuscitated sudden cardiac arrest (OR, 2.9 [95% CI, 1.0-8.6]; P = .05). Hospitalization-free and overall survival were similar among groups (P = .51 and P = .71, respectively).

CONCLUSIONS

Clinical categorization of patients with presumed CS identified a high-risk cohort comparable to patients with histologic evidence of disease, although caution should be exercised in reaching this diagnosis without paying due diligence to the differential diagnosis.

Manifestations and Outcome of Cardiac Sarcoidosis and Idiopathic Giant Cell Myocarditis by 25-Year Nationwide Cohorts

Background Cardiac sarcoidosis (CS) and giant cell myocarditis (GCM) share many histopathologic and clinical features. Whether they are parts of a one-disease continuum has been discussed. Methods and Results We compared medical record data of 351 CS and 28 GCM cases diagnosed in Finland since the late 1980s and followed until February 2018 for a composite end point of cardiac death, aborted sudden death, and heart transplantation. Heart failure was the presenting manifestation in 50% versus 15% (P<0.001), and high-grade atrioventricular block in 21% versus 43% (P=0.044), of GCM and CS, respectively. At presentation, left ventricular ejection fraction was ≤50% in 81% of cases of GCM versus in 48% of CS (P=0.004). The median (interquartile range) of plasma NT-proBNP (N-terminal pro-B-type natriuretic peptide) was 5273 (2782-11309) ng/L on admission in GCM versus 859 (290-1950) ng/L in CS (P<0.001), and cardiac troponin T exceeded 50 ng/L in 17 of 19 cases of GCM versus in 48 of 239 cases of CS (P<0.001). The 5-year estimate of event-free survival was 77% (95% CI, 72%-82%) in CS versus 27% (95% CI, 10%-45%) in GCM (P<0.001). By Cox regression analysis, GCM predicted cardiac events with a hazard ratio of 5.16 (95% CI, 2.82-9.45), which, however, decreased to 1.58 (95% CI, 0.71-3.52) after inclusion of markers of myocardial injury and dysfunction in the model. Conclusions GCM differs from CS in presenting with more extensive myocardial injury and having worse long-term outcome. Yet the key determinant of prognosis appears to be the extent of myocardial injury rather than the histopathologic diagnosis.

Management of Patients With Giant Cell Myocarditis: JACC Review Topic of the Week

Giant cell myocarditis is a rare, often rapidly progressive and potentially fatal, disease due to T-cell lymphocyte-mediated inflammation of the myocardium that typically affects young and middle-aged adults. Frequently, the disease course is marked by acute heart failure, cardiogenic shock, intractable ventricular arrhythmias, and/or heart block. Diagnosis is often difficult due to its varied clinical presentation and overlap with other cardiovascular conditions. Although cardiac biomarkers and multimodality imaging are often used as initial diagnostic tests, endomyocardial biopsy is required for definitive diagnosis. Combination immunosuppressive therapy, along with guideline-directed medical therapy, has led to a paradigm shift in the management of giant cell myocarditis resulting in an improvement in overall and transplant-free survival. Early diagnosis and prompt management can decrease the risk of transplantation or death, which remain common in patients who present with cardiogenic shock.

Epidemiological Impact of Myocarditis

Myocarditis is an inflammatory disease of the heart muscle with a wide range of potential etiological factors and consequently varying clinical patterns across the world. In this review, we address the epidemiology of myocarditis. Myocarditis was considered a rare disease until intensified research efforts in recent decades revealed its true epidemiological importance. While it remains a challenge to determine the true prevalence of myocarditis, studies are underway to obtain better approximations of the proportions of this disease. Nowadays, the prevalence of myocarditis has been reported from 10.2 to 105.6 per 100,000 worldwide, and its annual occurrence is estimated at about 1.8 million cases. This wide range of reported cases reflects the uncertainty surrounding the true prevalence and a potential underdiagnosis of this disease. Since myocarditis continues to be a significant public health issue, particularly in young adults in whom myocarditis is among the most common causes of sudden cardiac death, improved diagnostic and therapeutic procedures are necessary. This manuscript aims to summarize the current knowledge on the epidemiology of myocarditis, new diagnostic approaches and the current epidemiological impact of the COVID-19 pandemic.

Evaluation of Myocardial Gene Expression Profiling for Superior Diagnosis of Idiopathic Giant-Cell Myocarditis and Clinical Feasibility in a Large Cohort of Patients with Acute Cardiac Decompensation

Aims: The diagnostic approach to idiopathic giant-cell myocarditis (IGCM) is based on identifying various patterns of inflammatory cell infiltration and multinucleated giant cells (GCs) in histologic sections taken from endomyocardial biopsies (EMBs). The sampling error for detecting focally located GCs by histopathology is high, however. The aim of this study was to demonstrate the feasibility of gene profiling as a new diagnostic method in clinical practice, namely in a large cohort of patients suffering from acute cardiac decompensation. Methods and Results: In this retrospective multicenter study, EMBs taken from n = 427 patients with clinically acute cardiac decompensation and suspected acute myocarditis were screened (mean age: 47.03 ± 15.69 years). In each patient, the EMBs were analyzed on the basis of histology, immunohistology, molecular virology, and gene-expression profiling. Out of the total of n = 427 patient samples examined, GCs could be detected in 26 cases (6.1%) by histology. An established myocardial gene profile consisting of 27 genes was revealed; this was narrowed down to a specified profile of five genes (CPT1, CCL20, CCR5, CCR6, TLR8) which serve to identify histologically proven IGCM with high specificity in 25 of the 26 patients (96.2%). Once this newly established profiling approach was applied to the remaining patient samples, an additional n = 31 patients (7.3%) could be identified as having IGCM without any histologic proof of myocardial GCs. In a subgroup analysis, patients diagnosed with IGCM using this gene profiling respond in a similar fashion to immunosuppressive therapy as patients diagnosed with IGCM by conventional histology alone. Conclusions: Myocardial gene-expression profiling is a promising new method in clinical practice, one which can predict IGCM even in the absence of any direct histologic proof of GCs in EMB sections. Gene profiling is of great clinical relevance in terms of (a) overcoming the sampling error associated with purely histologic examinations and (b) monitoring the effectiveness of therapy.

Idiopathic giant cell myocarditis or cardiac sarcoidosis? A retrospective audit of a nationwide case series

Aims

Cardiac sarcoidosis (CS) and giant cell myocarditis (GCM) are inflammatory cardiomyopathies sharing histopathological and clinical features. Their differentiation is difficult and susceptible of confusion and apparent mistakes. The possibility that they represent different phenotypes of a single disease has been debated.

Methods and results

We made a retrospective audit of 73 cases of GCM diagnosed in Finland since the late 1980s. All available histological material was reanalyzed as were other examinations pertinent to the distinction between GCM and CS. Finding granulomas in or outside the heart was considered diagnostic of CS and exclusive of GCM. Altogether 45 of the 73 cases of GCM (62%) were reclassified as CS. In all except one case, this was based on finding sarcoid granulomas that either had been originally missed (n = 29) or misinterpreted (n = 11) or were found in additional posttransplant myocardial specimens (n = 3) or samples of extracardiac tissue (n = 1) accrued over the disease course. Supporting the reclassification, patients relocated to the CS group had less heart failure at presentation (prevalence 20% vs. 46%, P = 0.017) and better 1 year transplant‐free survival (82% vs. 45%, P = 0.011) than patients considered to represent true GCM.

Conclusions

Recognizing granulomas in or outside the heart remains a challenge for the pathologist. Given that CS and GCM are considered distinct diseases and granulomas exclusive of GCM, many cases of GCM, if thoroughly scrutinized, may need reclassification as CS. However, whether CS and GCM are truly different entities or parts of a one‐disease continuum has not yet been conclusively settled.

Review: Contrast-enhanced magnetic resonance in the diagnosis and management of cardiac sarcoidosis

Sarcoidosis is a relatively rare inflammatory condition which potentially carries high morbidity and substantial mortality. Due to the fact that it does not subject patients to ionizing radiation, has high temporal, spatial and contrast resolutions, cardiovascular magnetic resonance imaging (CMR) has become an important diagnostic and prognostic modality in the evaluation for cardiac involvement in this condition. This review provides relevant clinical and pathophysiological background on cardiac sarcoidosis, whilst detailing the role of CMR imaging in the diagnosis, and management of this condition.

The Many Faces of Cardiac Sarcoidosis

OBJECTIVES

The objective of this study was to review and illustrate the sometimes diagnostically challenging features of cardiac sarcoidosis. We emphasize variable phenotypes presented at explant and biopsy evaluation and review literature regarding ancillary clinical and pathologic studies to enhance diagnostic accuracy.

METHODS

A literature review was performed and two cardiac sarcoidosis cases were illustrated.

RESULTS

Our cases and literature review demonstrate the pathologic spectrum of cardiac sarcoidosis. Irregular left ventricular free wall involvement is most common, followed by the interventricular septum and right ventricle. Although granulomas are often composed of tight epithelioid macrophage aggregates, early granulomas comprise loosely associated macrophages with lymphocyte predominance. Chronic disease leads to fibrosis and end-stage heart failure. Sampling errors and variable histology cause low endomyocardial biopsy sensitivity.

CONCLUSIONS

Current guidelines use clinical, radiologic, and immunohistologic criteria for diagnosing cardiac sarcoidosis. Knowledge of these guidelines will assist pathologists in making accurate diagnosis of this disease.

Recognition and Initial Management of Fulminant Myocarditis: A Scientific Statement From the American Heart Association

Fulminant myocarditis (FM) is an uncommon syndrome characterized by sudden and severe diffuse cardiac inflammation often leading to death resulting from cardiogenic shock, ventricular arrhythmias, or multiorgan system failure. Historically, FM was almost exclusively diagnosed at autopsy. By definition, all patients with FM will need some form of inotropic or mechanical circulatory support to maintain end-organ perfusion until transplantation or recovery. Specific subtypes of FM may respond to immunomodulatory therapy in addition to guideline-directed medical care. Despite the increasing availability of circulatory support, orthotopic heart transplantation, and disease-specific treatments, patients with FM experience significant morbidity and mortality as a result of a delay in diagnosis and initiation of circulatory support and lack of appropriately trained specialists to manage the condition. This scientific statement outlines the resources necessary to manage the spectrum of FM, including extracorporeal life support, percutaneous and durable ventricular assist devices, transplantation capabilities, and specialists in advanced heart failure, cardiothoracic surgery, cardiac pathology, immunology, and infectious disease. Education of frontline providers who are most likely to encounter FM first is essential to increase timely access to appropriately resourced facilities, to prevent multiorgan system failure, and to tailor disease-specific therapy as early as possible in the disease process.

Myocarditis in Humans and in Experimental Animal Models

Myocarditis is defined as an inflammation of the cardiac muscle. In humans, various infectious and non-infectious triggers induce myocarditis with a broad spectrum of histological presentations and clinical symptoms of the disease. Myocarditis often resolves spontaneously, but some patients develop heart failure and require organ transplantation. The need to understand cellular and molecular mechanisms of inflammatory heart diseases led to the development of mouse models for experimental myocarditis. It has been shown that pathogenic agents inducing myocarditis in humans can often trigger the disease in mice. Due to multiple etiologies of inflammatory heart diseases in humans, a number of different experimental approaches have been developed to induce myocarditis in mice. Accordingly, experimental myocarditis in mice can be induced by infection with cardiotropic agents, such as coxsackievirus B3 and protozoan parasite Trypanosoma cruzi or by activating autoimmune responses against heart-specific antigens. In certain models, myocarditis is followed by the phenotype of dilated cardiomyopathy and the end stage of heart failure. This review describes the most commonly used mouse models of experimental myocarditis with a focus on the role of the innate and adaptive immune systems in induction and progression of the disease. The review discusses also advantages and limitations of individual mouse models in the context of the clinical manifestation and the course of the disease in humans. Finally, animal-free alternatives in myocarditis research are outlined.

A Unique Case of Complete Atrioventricular Block Rapidly Progressing to Diastolic and Systolic Dysfunction in Cardiac Sarcoidosis

Sarcoidosis is a multisystem granulomatous disease that most commonly affects the lungs but can affect other organs including the heart due to granuloma infiltration. Atrioventricular block is a common manifestation of cardiac sarcoidosis which can progress to sudden cardiac death. We report a case of cardiac sarcoidosis presenting as complete heart block, progressing to diastolic and systolic dysfunction without extracardiac manifestations early in the disease. This case stresses the importance of having a high index of suspicion for cardiac sarcoidosis in patients presenting with atrioventricular block of unknown etiology.

Long-Term Outcome in Probable Versus Absolute Cardiac Sarcoidosis

Suspicion of cardiac sarcoidosis (CS) arises when a patient has clinical cardiac manifestations and findings on cardiac imaging suggestive of inflammatory cardiomyopathy with or without history of extracardiac sarcoidosis. The additional requirement for diagnosis is proof of sarcoidosis histology. Endomyocardial biopsy (EMB) showing granulomatous inflammation in absence of other explanations confirms an absolute diagnosis of CS while similar histology in an extracardiac biopsy gives a probable diagnosis of CS. Our aim was to study the equivalence of probable to absolute CS in terms of patients' characteristics and outcome. We reviewed the available clinical information, diagnostic procedures, details of treatment and event-free survival of 149 consecutive patients (103 women, mean age 50 y) diagnosed with CS at our institution. The diagnosis was absolute in 68 patients and probable in 81 patients. There was no difference in age or sex distribution between the diagnostic subgroups but left ventricular dysfunction on echocardiography (ejection fraction <50%) was more common in absolute CS (60% vs 36%, p = 0.003) as was abnormal myocardial late gadolinium enhancement on magnetic resonance imaging (96% vs 78%, p = 0.006). Over a median of 54 months of follow-up, 19 of 68 patients with absolute CS versus 15 of 81 with probable CS either died, suffered an aborted sudden cardiac death or underwent cardiac transplantation (log rank p = 0.334). In conclusion, in terms of prognosis, clinical diagnosis of CS supported by extracardiac histology is equivalent to diagnosis confirmed by myocardial histology. No distinction should be made between probable and absolute CS as regards treatment and follow-up.

Catheter ablation for ventricular tachycardia in patients with cardiac sarcoidosis: a systematic review

Aims

Cardiac sarcoidosis (CS) is associated with a poor prognosis. Important features of CS include heart failure, conduction abnormalities, and ventricular arrhythmias. Ventricular tachycardia (VT) is often refractory to antiarrhythmic drugs (AAD) and immunosuppression. Catheter ablation has emerged as a treatment option for recurrent VT. However, data on the efficacy and outcomes of VT ablation in this context are sparse.

Methods and results

A systematic search was performed on PubMed, EMBASE, and Cochrane database (from inception to September 2016) with included studies providing a minimum of information on CS patients undergoing VT ablation: age, gender, VT cycle length, CS diagnosis criteria, and baseline medications. Five studies reporting on 83 patients were identified. The mean age of patients was 50 ± 8 years, 53/30 (males/females) with a maximum of 56 patients receiving immunosuppressive therapy, mean ejection fraction was 39.1 ± 3.1% and 94% had an implantable cardioverter defibrillator in situ. The median number of VTs was 3 (2.6-4.9)/patient, mean cycle length of 360 ms (326-400 ms). Hundred percent of VTs received endocardial ablation, and 18% required epicardial ablation. The complication rates were 4.7-6.3%. Relapse occurred in 45 (54.2%) patients with an incidence of relapse 0.33 (95% confidence interval 0.108-0.551, P < 0.004). Employing a less stringent endpoint (i.e. freedom from arrhythmia or reduction of ventricular arrhythmia burden), 61 (88.4%) patients improved following ablation.

Conclusions

These data support the utilization of catheter ablation in selected CS cases resistant to medical treatment. However, data are derived from observational non-controlled case series, with low-methodological quality. Therefore, future well-designed, randomized controlled trials, or large-scale registries are required.

Acute and Fulminant Myocarditis: a Pragmatic Clinical Approach to Diagnosis and Treatment

PURPOSE OF REVIEW

To review the clinical features of acute myocarditis, including its fulminant presentation, and present a pragmatic approach to the diagnosis and treatment, considering indications of American and European Scientific Statements and recent data derived by large contemporary registries.

RECENT FINDINGS

Patients presenting with acute uncomplicated myocarditis (i.e., without left ventricular dysfunction, heart failure, or ventricular arrhythmias) have a favorable short- and long-term prognosis: these findings do not support the indication to endomyocardial biopsy in this clinical scenario. Conversely, patients with complicated presentations, especially those with fulminant myocarditis, require an aggressive and comprehensive management, including endomyocardial biopsy and availability of advanced therapies for circulatory support. Although several immunomodulatory or immunosuppressive therapies have been studied and are actually prescribed in the real-world practice, their effectiveness has not been clearly demonstrated. Patients with specific histological subtypes of acute myocarditis (i.e., giant cell and eosinophilic myocarditis) or those affected by sarcoidosis or systemic autoimmune disorders seem to benefit most from immunosuppression. On the other hand, no clear evidence supports the use of immunosuppressive agents in patients with lymphocytic acute myocarditis, even though small series suggest a potential benefit. Acute myocarditis is a heterogeneous condition with distinct pathophysiological pathways. Further research is mandatory to identify factors and mechanisms that may trigger/maintain or counteract/repair the myocardial damage, in order to provide a rational for future evidence-based treatment of patients affected by this condition.

Echocardiography in Sarcoidosis

PURPOSE OF REVIEW

Cardiac sarcoidosis (CS) is associated with significant morbidity and mortality. The diagnosis of CS is challenging and typically one that is only entertained after many other conditions have been ruled out. A high index of suspicion is necessary in order to correctly determine appropriate testing for the disease. Transthoracic echocardiography is the most readily available imaging modality available to help establish a diagnosis in a potential patient. However, no one echocardiographic feature is pathognomonic.

RECENT FINDINGS

On echocardiography, unusual wall motion abnormalities, which do not fit a classic coronary distribution, along with diastolic dysfunction may alert one to the presence of cardiac sarcoid, particularly in the right clinical context. Myocardial strain imaging on echocardiography may increase the sensitivity of identifying cardiac sarcoidosis. Alternative imaging with cardiac magnetic resonance imaging or positron emission tomography have become more frequently utilized to establish a diagnosis of CS. Cardiac sarcoidosis remains a difficult condition to diagnose. However early diagnosis is critical to decrease the associated high mortality. Endomyocardial biopsy is highly specific but lacks sensitivity due to the patchy nature of the granulomatous deposition. Thus, imaging plays a role in diagnosis as well as for follow-up. Echocardiography remains an hallmark during the workup for CS. Decreased sensitivity of echocardiography has facilitated the use of other techniques to establish the presence of CS.

[Inflammatory cardiomyopathy and myocarditis]

We describe diagnosis, differential diagnosis, multimodality imaging and medical and invasive diagnostic treatment in patients with inflammatory cardiomyopathy and myocarditis under etiological considerations in reference to a landmark position paper of the Working Group Myocardial and Pericardial Diseases of the European Society of Cardiology together with recent developments in diagnosis and treatment. Diagnosis of the symptomatic patient is the assessment of etiology of inflammatory cardiomyopathy, followed by the clinical presentation, course, treatment option and prognosis. Viral myocarditis in its different facets can clearly be separated from autoreactive forms by histological and molecular methods in the endomyocardial biopsy, thus leading to an individualized targeted therapy beyond heart failure treatment.