Incidence, Risk Factors, and Outcome of Life-Threatening Ventricular Arrhythmias in Giant Cell Myocarditis

Giant Cell Myocarditis: Navigating Diagnosis and Management of a Mysterious Entity

Giant cell myocarditis (GCM) is a rare but often fatal disease commonly affecting young adults. Its nonspecific presentation and possible co-occurrence with other cardiac diseases make it a challenging diagnosis. We report a case of 48-year-old patient who presented with progressive dyspnea on exertion due to GCM, and discuss their hospital course leading to recovery. We also review the literature on this rare disease entity, highlighting its diagnosis and management.

Management of patients with myocarditis and arrhythmogenic phenotype

Acute myocarditis (AM) is an inflammatory condition of the myocardium that may lead to severe complications, including acute heart failure and life-threatening ventricular arrhythmias (VAs). In-hospital VAs are estimated to affect 2.5% of adult patients with AM. Recent insights suggest a genetic predisposition to develop VA in a subset of patients with AM. This review will focus on arrhythmogenic manifestations of AM, highlighting risk stratification for VA after an acute episode and the contribution of genetic factors, emphasizing the need to integrate clinical, imaging, and genetic findings. In addition, prognostic information derived from cardiac magnetic resonance imaging will be discussed, pointing out the association between VA and the presence, extension, and septal localization of late gadolinium enhancement. The overlap between inherited arrhythmogenic and inflammatory cardiomyopathies will be explored, with specific attention to the identification of desmosomal gene variants, which are associated with recurrent myocarditis-like episodes and a higher risk of VA. Cardiac sarcoidosis, giant cell myocarditis, and immune checkpoint inhibitors-related myocarditis will be discussed as a paradigm of inflammatory cardiomyopathies with increased arrhythmic burden. Finally, the clinical challenges of managing patients with AM and arrhythmogenic presentation will be tackled, looking at indications for implantable cardioverter defibrillators after the acute phase.

A giant and rapid myocardial remodeling due to fatal giant cell myocarditis: a case report

Giant cell myocarditis is a rare and rapidly progressive disease with a high mortality rate. We present the case of a 21-year-old male without a medical history who presented with a giant left ventricle (9.9 cm, EF:10%) and in a severe clinical state. Cardiac MRI and virology raised the suspicion of giant cell myocarditis. Concerned about the hemodynamic and respiratory deterioration, we initiated cardiac transplant therapy. A fatal ventricular fibrillation occurs while waiting for the heart transplant. Sudden death could represent the "first symptom" of pathological findings. It is important to recognize that while sudden death due to giant cell myocarditis may be rare, it is still a potentially serious complication of giant cell infection and should be considered in cases of unexplained sudden death. In addition, this case highlights the challenges in the diagnosis and management of giant cell myocarditis and the need for early recognition and aggressive treatment.

Atrial FDG Uptake: Etiologies, Clinical Significance, and Implications

PURPOSE OF REVIEW

This review aims to explore the clinical significance of atrial fluorodeoxyglucose (FDG) uptake observed in positron emission tomography (PET) scans, focusing on its association with atrial fibrillation (AF), cardiac sarcoidosis, and myocarditis. We discuss the implications of atrial uptake for patient management and prognosis.

RECENT FINDINGS

Recent studies have demonstrated that atrial FDG uptake is frequently present in patients with AF, particularly those with persistent AF, and is linked to increased risks of stroke and poorer outcomes after ablation. In cardiac sarcoidosis, atrial uptake correlates with inflammation and an elevated risk of AF. Additionally, non-granulomatous myocarditis has been associated with localized atrial FDG uptake, necessitating careful differentiation from other causes. : Atrial FDG uptake reflects underlying pathological processes such as inflammation, which can significantly impact patient management and outcomes across various cardiovascular diseases. Recognizing these findings can facilitate early intervention, improve prognosis, and support the development of clear guidelines for clinical practice, emphasizing the need for continued research in this area.

In Vivo Cardiovascular Molecular Imaging: Contributions to Precision Medicine and Drug Development

Conventional forms of noninvasive cardiovascular imaging that evaluate morphology, function, flow, and metabolism play a vital role in individual treatment decisions, often based on guidelines. Innovations in molecular imaging have enhanced our ability to spatially quantify the expression of a wider array of disease-related proteins, genes, or cell types, or the activity of specific pathogenic pathways. These techniques, which usually rely on design of targeted imaging probes, have already been used extensively in cancer medicine and have now become part of cardiovascular care in conditions such as amyloidosis and sarcoidosis. The recognition that common cardiovascular conditions are caused by a substantial diversity of pathobiologic pathways and the diversity of therapies available for use have rekindled interest in expanding the role of molecular imaging of tissue phenotype to improve precision in diagnosis and therapeutic decision-making. The intent of this article is to raise awareness and understanding of approaches to molecular or cellular imaging of phenotype with targeted probes, and their potential to promote the principles of precision medicine. Also addressed are the diverse roles of molecular imaging to improve precision and efficiency of new drug development at the stages of candidate identification, preclinical testing, and clinical trials.

Cardiovascular outcomes among giant cell myocarditis compared with cardiac sarcoidosis: A propensity score-matched analysis

BACKGROUND

Giant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are rare inflammatory diseases of the myocardium with poor prognosis. Cardiovascular disease outcomes among both diseases have not been well studied with limited literature.

OBJECTIVE

This study aims to investigate the cardiovascular outcomes among patients with GCM and CS.

METHOD

We queried the TriNeTX Global Collaborative Network for adult patients with giant cell myocarditis and cardiac sarcoidosis between January 2000 to May 2023 and created two groups: one with giant cell myocarditis and second with cardiac sarcoidosis. Both the groups were followed for 6 months and 12 months.

RESULT

After propensity score matched analysis (PSM), among the 4804 patients (2402 patients in each group), the mean age of patients was 57.1 and 57.6 years in GCM and CS groups, respectively. PSM analysis showed that primary outcome i.e., all-cause mortality was significantly higher in GCM group both after 6 months [relative risk (RR) 2.33, 95 % confidence interval (CI): 1.64-3.30, p < 0.01] and 1 year follow up [RR, 1.54 (95 % CI: 1.20-1.98), p < 0.01] as compared with CS group. However, secondary outcomes i.e., heart failure (HF) at 6 month (RR 0.66, 95 % CI: 0.52-0.85, p < 0.01), and at 1 year (RR 0.60, 95 % CI: 0.49-0.73, p < 0.01), ventricular tachycardia (VT) at 6 months (RR 0.34, 95 % CI: 0.25-0.46, p < 0.01), and at 1 year (RR 0.32, 95 % CI: 0.25-0.41, p < 0.01), atrioventricular (AV) node block at 6 month (RR 0.45, 95 % CI: 0.33-0.61, p < 0.01), and at 1 year (RR 0.43, 95 % CI: 0.34-0.55, p < 0.01), and atrial flutter and fibrillation (AF) at 6 months (RR 0.67, 95 % CI: 0.48-0.94, p = 0.02), and at 1 year (RR 0.59, 95 % CI: 0.45-0.76, p < 0.01) were found significantly lower in GCM group as compared to CS group. On the other hand, heart transplant incidence was comparable between both the groups.

CONCLUSION

These findings suggest that GCM patients have high risk of mortality and lower risk of HF, VT, AV node block, and AF when compared with CS.

What are the early warning signs of myocarditis during the pathway of care?

INTRODUCTION

Myocarditis is an inflammatory disease of the myocardial layer of the heart that can be prone to dilation of chambers with presentation as heart failure secondary to dilated cardiomyopathy. Myocarditis can lead to remodeling and fibrosis that can affect the heart's relaxation-lusitropy and chronotropic function. The current techniques for identifying myocarditis, such as endomyocardial biopsy and imaging, are costly, and intrusive. The current literature aims to identify reliable, accurate, and prognostically educative biomarkers of myocarditis.

AREAS COVERED

This review covers the definition, clinical features, diagnostic markers, cardiac imaging, prognosis, and complications of myocarditis. PubMed, Embase, and the Cochrane data bank were searched from inception to 1 January 2024 for relevant articles.

EXPERT OPINION

By adopting these diagnostic and prognostic biomarkers, clinicians can have a better comprehension of the progression of the disease and provide early diagnosis and treatment for myocarditis.

Diagnosis and treatment of myocarditis and inflammatory cardiomyopathy. Consensus document of the SEC-Working Group on Myocarditis

Myocarditis is defined as myocardial inflammation and its etiology is highly diverse, including infectious agents, drugs, and autoimmune diseases. The clinical presentation also varies widely, extending beyond the classic clinical picture of acute chest pain, and includes cases of cardiomyopathy of unknown cause whose etiology may be inflammatory. Because certain patients may benefit from targeted treatments, the search for the etiology should begin when myocarditis is first suspected. There remain several areas of uncertainty in the diagnosis and treatment of this disease. Consequently, this consensus document aims to provide clear recommendations for its diagnosis and treatment. Hence, a diagnostic algorithm is proposed, specifying when non-invasive diagnosis with cardiac MR is appropriate vs a noninvasive approach with endomyocardial biopsy. In addition, more novel aspects are discussed, such as when to suspect an underlying genetic etiology. The recommendations cover the management of myocarditis and inflammatory cardiomyopathy, both for general complications and specific clinical entities.

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.

Red Flags in Acute Myocarditis

Acute myocarditis is an inflammatory disease of the heart that may occur in the setting of infection, immune system activation or exposure to certain drugs. Often, it is caused by viruses, whereby the clinical course is usually benign; however, it may also present with rapidly progressive fulminant myocarditis, which is associated with high morbidity and mortality. This review highlights the critical red flags - from the clinical, biochemical, imaging and histopathological perspectives - that should raise the index of suspicion of acute myocarditis. We also present an illustrative case of a young female patient with rapidly progressive cardiogenic shock requiring veno-arterial extracorporeal membrane oxygenation as a bridge to orthotopic heart transplantation. The patient showed no clinical or echocardiographic recovery signs and eventually underwent orthotopic heart transplantation. Furthermore, we elaborate on the classifications of acute myocarditis based on clinical presentation and histopathology classifications, focusing on identifying key red flags that will inform early diagnosis and appropriate management in such challenging cases.

Biomarkers in Acute Myocarditis and Chronic Inflammatory Cardiomyopathy: An Updated Review of the Literature

Myocarditis is a disease caused by cardiac inflammation that can progress to dilated cardiomyopathy, heart failure, and eventually death. Several etiologies, including autoimmune, drug-induced, and infectious, lead to inflammation, which causes damage to the myocardium, followed by remodeling and fibrosis. Although there has been an increasing understanding of pathophysiology, early and accurate diagnosis, and effective treatment remain challenging due to the high heterogeneity. As a result, many patients have poor prognosis, with those surviving at risk of long-term sequelae. Current diagnostic methods, including imaging and endomyocardial biopsy, are, at times, expensive, invasive, and not always performed early enough to affect disease progression. Therefore, the identification of accurate, cost-effective, and prognostically informative biomarkers is critical for screening and treatment. The review then focuses on the biomarkers currently associated with these conditions, which have been extensively studied via blood tests and imaging techniques. The information within this review was retrieved through extensive literature research conducted on major publicly accessible databases and has been collated and revised by an international panel of experts. The biomarkers discussed in the article have shown great promise in clinical research studies and provide clinicians with essential tools for early diagnosis and improved outcomes.

Gallium-68 fibroblast activation protein inhibitor positron emission tomography in cardiovascular disease

Gallium-68 fibroblast activation protein inhibitor [(68Ga)Ga-FAPI] is a new radiopharmaceutical positioning itself as the preferred agent in patients with malignant tumours, competing with 2-Deoxy-2-[18F]fluoro-d-glucose [2-(18F)FDG] using positron emission tomography (PET). While imaging oncology patients with [68Ga]Ga-FAPI PET, incidental uptake of [68Ga]Ga-FAPI has been detected in the myocardium. This review summarises original research studies associating the visualisation of FAPI-based tracers in the myocardium with underlying active cardiovascular disease.

Myocarditis: Etiology, Pathogenesis, and Their Implications in Clinical Practice

Myocarditis is an inflammatory disease of the myocardium caused by infectious or non-infectious agents. It can lead to serious short-term and long-term sequalae, such as sudden cardiac death or dilated cardiomyopathy. Due to its heterogenous clinical presentation and disease course, challenging diagnosis and limited evidence for prognostic stratification, myocarditis poses a great challenge to clinicians. As it stands, the pathogenesis and etiology of myocarditis is only partially understood. Moreover, the impact of certain clinical features on risk assessment, patient outcomes and treatment options is not entirely clear. Such data, however, are essential in order to personalize patient care and implement novel therapeutic strategies. In this review, we discuss the possible etiologies of myocarditis, outline the key processes governing its pathogenesis and summarize best available evidence regarding patient outcomes and state-of-the-art therapeutic approaches.

Prognostic Implications of Sarcoidosis Granulomas - Insights From the Multicenter Registry, the Japanese Cardiac Sarcoidosis Prognostic Study

Background: Definitions of cardiac sarcoidosis (CS) differ among guidelines. Any systemic histological finding of CS is essential for the diagnosis of CS in the 2014 Heart Rhythm Society statement, but not necessary in the Japanese Circulation Society 2016 guidelines. This study aimed to reveal the differences in outcomes by comparing 2 groups, namely CS patients with or without systemic histologically proven granuloma. Methods and Results: This study retrospectively included 231 consecutive patients with CS. CS with granulomas in ≥1 organs was diagnosed in 131 patients (Group G), whereas CS without any granulomas was diagnosed in the remaining 100 patients (Group NG). Left ventricular ejection fraction (LVEF) was significantly reduced in Group NG compared with Group G (44±13% vs. 50±16%, respectively; P=0.001). However, Kaplan-Meier curves showed that major adverse cardiovascular events (MACE)-free survival outcomes were comparable between the 2 groups (log-rank P=0.167). Univariable analyses showed that significant predictors of MACE were Groups G/NG, histological CS, LVEF, and high B-type natriuretic peptide (BNP) or N-terminal pro BNP concentrations, but none of these was significant in multivariable analyses. Conclusions: Overall risks of MACE were similar between the 2 groups despite different manifestations in cardiac dysfunction. The data not only validate the prognostic value of non-invasive diagnosis of CS, but also show the need for careful observation and therapeutic strategy in patients with CS without any granuloma.

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.

Giant cell myocarditis following COVID-19 successfully treated by immunosuppressive therapy

It has been shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), by coronavirus disease 2019 (COVID-19), can lead to multi-organ impairment including cardiac involvement and immunological problems. Acute myocarditis is one of serious and fatal complications of COVID-19. In this case report, we present a 46-year-old lady with a history of lichen planus dermatitis who has developed a rapidly progressive heart failure after an episode of COVID-19. The pathologic examination of her endomyocardial biopsy specimens was compatible with GCM, and she was successfully treated with a combined immunosuppressive therapy regimen.

Giant Cell Myocarditis after First Dose of BNT162b2 - a Case Report

Herein we report the case of a young man, admitted to the Department of Cardiology and Angiology at Hannover Medical School with shortness of breath and elevated troponin. Few weeks earlier the patient received the first dose of BioNTech's mRNA vaccine (Comirnaty, BNT162b2). After diagnostic work‐up revealed giant cell myocarditis, the patient received immunosuppressive therapy. In the present context of myocarditis after mRNA vaccination we discuss this rare aetiology and the patient's treatment strategy in the light of current recommendations.

Bidirectional Ventricular Tachycardia in a Patient With Fulminant Myocarditis Secondary to Cardiac Sarcoidosis Mimicking Giant Cell Myocarditis

Differentiating between sarcoidosis and giant cell myocarditis (GCM) based on clinical presentation is difficult. We present the case of a 57-year-old woman who was initially diagnosed with GCM based on endomyocardial biopsy. The patient was refractory to standard management for GCM and went on to develop bidirectional ventricular tachycardia, a finding suggestive of sarcoidosis. Unfortunately, the patient eventually needed cardiac transplantation. The explanted heart demonstrated cardiac sarcoidosis. Bidirectional ventricular tachycardia has not been demonstrated in GCM, and its presence may help in distinguishing between GCM and cardiac sarcoidosis.

Post-discharge arrhythmic risk stratification of patients with acute myocarditis and life-threatening ventricular tachyarrhythmias

AIMS

The outcomes of patients presenting with acute myocarditis and life-threatening ventricular arrhythmias (LT-VA) are unclear. The aim of this study was to assess the incidence and predictors of recurrent major arrhythmic events (MAEs) after hospital discharge in this patient population.

METHODS AND RESULTS

We retrospectively analysed 156 patients (median age 44 years; 77% male) discharged with a diagnosis of acute myocarditis and LT-VA from 16 hospitals worldwide. Diagnosis of myocarditis was based on histology or the combination of increased markers of cardiac injury and cardiac magnetic resonance (CMR) Lake Louise criteria. MAEs were defined as the relapse, after discharge, of sudden cardiac death or successfully defibrillated ventricular fibrillation, or sustained ventricular tachycardia (sVT) requiring implantable cardioverter-defibrillator therapy or synchronized external cardioversion. Median follow-up was 23 months [first to third quartile (Q1-Q3) 7-60]. Fifty-eight (37.2%) patients experienced MAEs after discharge, at a median of 8 months (Q1-Q3 2.5-24.0 months; 60.3% of MAEs within the first year). At multivariable Cox analysis, variables independently associated with MAEs were presentation with sVT [hazard ratio (HR) 2.90, 95% confidence interval (CI) 1.38-6.11]; late gadolinium enhancement involving ≥2 myocardial segments (HR 4.51, 95% CI 2.39-8.53), and absence of positive short-tau inversion recovery (STIR) (HR 2.59, 95% CI 1.40-4.79) at first CMR.

CONCLUSIONS

Among patients discharged with a diagnosis of myocarditis and LT-VA, 37.2% had recurrences of MAEs during follow-up. Initial CMR pattern and sVT at presentation stratify the risk of arrhythmia recurrence.

Late gadolinium enhancement characteristics in giant cell myocarditis

AIMS

This study aims to demonstrate the characteristics of late gadolinium enhancement (LGE) assessed by cardiovascular magnetic resonance (CMR) imaging in patients with giant cell myocarditis (GCM).

METHODS AND RESULTS

Six patients histologically diagnosed with GCM were retrospectively recruited in this study. All of them underwent CMR during hospitalization. The distribution and extent of LGE were assessed on both ventricles, and the AHA-17 segment model was used for left ventricular (LV) analysis. Nine case reports with CMR in GCM were reviewed and summarized to investigate the features of LGE further. LGE was detected on both ventricular walls in all subjects. For a detailed analysis of LGE in the LV, the extent ranged from 21.6% to 56%. Among 70 segments (68.6%) involved by LGE, the subendocardial LGE was the most common pattern (46/102, including 24 segments located in the right-sided septum), followed by the subepicardial pattern (23/102). The right-sided septum, the subepicardial anterior wall, and the subendocardial right ventricular (RV) wall were observed in all subjects. To summarize the results of the present study with these case reports, the three most common patterns of LGE are the right-sided septum (73%), the subepicardial anterior wall (60%), and the subendocardial RV wall (53%).

CONCLUSIONS

Extensive LGE seems to be common in GCM, affecting both LV and RV walls. Apart from subepicardial LGE, subendocardial LGE, which was used to be implicated in ischaemic disease, was frequently presented in GCM. The right-sided subendocardial septum, the subepicardial anterior wall, and the subendocardial RV wall might be the vulnerable areas of LGE in GCM.

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.

Giant cell myocarditis causing sudden death in a patient with sarcoidosis

Giant cell myocarditis (GCM) is a rare and rapidly fatal cardiovascular condition most often seen in young adults. It is characterized microscopically by myocardial necrosis with multinucleated giant cells in the absence of well-defined granulomas. This disorder has typically been attributed to manifest as heart failure, but in some individuals, GCM may present as sudden cardiac death. Herein, we present a fatal case of GCM in a 36-year-old male with a history of autoimmune disorders. The decedent presented to the emergency room due to vomiting and was treated for nausea due to suspected dehydration. He was discharged that night and found dead on his bathroom floor the following day. Postmortem examination revealed psoriasis and granulomatous lesions in the lungs consistent with sarcoidosis, further supporting circumstantial evidence existing between GCM and autoimmune disorders. Additionally, this case provides an opportunity to distinguish GCM from the distinct clinical entity of cardiac sarcoidosis (CS), especially in the setting of systemic sarcoidosis. We hope to raise awareness of this rare disease process and its potential to cause sudden cardiac death so that it may be considered in a differential diagnosis as immunosuppression and early cardiac transplantation largely determine the prognosis.

Arrhythmias Associated with Inflammatory Cardiomyopathies

Purpose of review

To provide an approach to the diagnosis and treatment of arrhythmias associated with inflammatory cardiomyopathies.

Recent findings

Inflammatory cardiomyopathies are increasingly recognized as the etiology of both ventricular and supraventricular arrhythmias. There have been recent studies providing novel insights into the pathogenesis of arrhythmias in inflammatory cardiomyopathies and exploring the role of various diagnostic tools and treatment strategies.

Summary

Patients with inflammatory cardiomyopathies often present with one or more arrhythmias, including atrioventricular block, atrial and ventricular tachyarrhythmias, and occasionally sudden cardiac death. Given dynamic pathophysiology and heterogeneous presentation, the management of arrhythmias in these patients presents unique challenges. We review the current approach to the diagnosis and treatment of arrhythmias in this challenging cohort of patients with an emphasis on cardiac sarcoidosis.

Supplementary Information

The online version of this article (10.1007/s11936-020-00871-5) contains supplementary material, which is available to authorized users.

Cardiac fibrosis

Myocardial fibrosis, the expansion of the cardiac interstitium through deposition of extracellular matrix proteins, is a common pathophysiologic companion of many different myocardial conditions. Fibrosis may reflect activation of reparative or maladaptive processes. Activated fibroblasts and myofibroblasts are the central cellular effectors in cardiac fibrosis, serving as the main source of matrix proteins. Immune cells, vascular cells and cardiomyocytes may also acquire a fibrogenic phenotype under conditions of stress, activating fibroblast populations. Fibrogenic growth factors (such as transforming growth factor-β and platelet-derived growth factors), cytokines [including tumour necrosis factor-α, interleukin (IL)-1, IL-6, IL-10, and IL-4], and neurohumoral pathways trigger fibrogenic signalling cascades through binding to surface receptors, and activation of downstream signalling cascades. In addition, matricellular macromolecules are deposited in the remodelling myocardium and regulate matrix assembly, while modulating signal transduction cascades and protease or growth factor activity. Cardiac fibroblasts can also sense mechanical stress through mechanosensitive receptors, ion channels and integrins, activating intracellular fibrogenic cascades that contribute to fibrosis in response to pressure overload. Although subpopulations of fibroblast-like cells may exert important protective actions in both reparative and interstitial/perivascular fibrosis, ultimately fibrotic changes perturb systolic and diastolic function, and may play an important role in the pathogenesis of arrhythmias. This review article discusses the molecular mechanisms involved in the pathogenesis of cardiac fibrosis in various myocardial diseases, including myocardial infarction, heart failure with reduced or preserved ejection fraction, genetic cardiomyopathies, and diabetic heart disease. Development of fibrosis-targeting therapies for patients with myocardial diseases will require not only understanding of the functional pluralism of cardiac fibroblasts and dissection of the molecular basis for fibrotic remodelling, but also appreciation of the pathophysiologic heterogeneity of fibrosis-associated myocardial disease.

An unusual cause of ventricular fibrillatory arrest

Myocarditis is an important cause of arrhythmogenic sudden cardiac arrest in the young. A strong index of suspicion is required as not only can arrhythmias be the only clinical manifestation but also because these patients can have normal cardiac biomarkers, electrocardiographic and echocardiographic findings, and inflammatory markers. Patients with ventricular arrhythmias in the setting of viral myocarditis, especially the ones in whom cardiac MRI findings normalise upon follow-up, tend to do well in the long run and an implantable cardioverter-defibrillator should be avoided in these patients; instead, a wearable defibrillator should be temporarily used as we did in this 7-year-old.

Sudden cardiac death due to ventricular fibrillation in a case of giant cell myocarditis

A 70-year-old woman was admitted to our hospital complaining of shortness of breath. She was diagnosed with acute decompensated heart failure due to left ventricular dysfunction. Her symptoms began to improve with standard therapy for heart failure with diuretics, noninvasive pressure ventilation, and inotropes, but paroxysmal atrial fibrillation and premature ventricular contractions (PVCs) occurred. After treatment with amiodarone, the number of PVCs decreased, and the left ventricular wall motion gradually improved. However, on day 28, ventricular fibrillation and cardiopulmonary arrest occurred suddenly, and she could not be resuscitated. She was diagnosed with giant cell myocarditis via an autopsy. The autopsy revealed diffuse inflammatory cells that comprised giant cells and eosinophils as well as cellular degeneration and necrosis. <Learning objective: We herein report a case of sudden cardiac death due to giant cell myocarditis diagnosed at an autopsy.>.

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.

Diagnostic and prognostic role of electrocardiogram in acute myocarditis: A comprehensive review

Background

Acute myocarditis represents a challenging diagnosis as there is no pathognomonic clinical presentation. In patients with myocarditis, electrocardiogram (ECG) can display a variety of non‐specific abnormalities. Nevertheless, ECG is widely used as an initial screening tool for myocarditis.

Methods

We researched all possible ECG alterations during acute myocarditis evaluating prevalence, physiopathology, correlation with clinical presentation patterns, role in differential diagnosis, and prognostic yield.

Results

The most common ECG abnormality in myocarditis is sinus tachycardia associated with nonspecific ST/T‐wave changes. The presence of PR segment depression both in precordial and limb leads, a PR segment depression in leads with ST segment elevation, a PR segment elevation in aVR lead or a ST elevation with pericarditis pattern favor generally diagnosis of perimyocarditis rather than myocardial infarction. In patients with acute myocarditis, features associated with a poorer prognosis are: pathological Q wave, wide QRS complex, QRS/T angle ≥ 100°, prolonged QT interval, high‐degree atrioventricular block and malignant ventricular tachyarrhythmia. On the contrary, ST elevation with a typical early repolarization pattern is associated with a better prognosis.

Conclusions

ECG alterations in acute myocarditis could be very useful in clinical practice for a patient‐tailored approach in order to decide appropriate therapy, length of hospitalization, and frequency of followup.

Fulminant giant-cell myocarditis on mechanical circulatory support: Management and outcomes of a French multicentre cohort

AIMS

Giant-cell myocarditis (GCM) is a rare and often fatal form of myocarditis. Only a few reports have focused on fulminant forms. We describe the clinical characteristics, management and outcomes of GCM patients rescued by mechanical circulatory support (MCS).

METHODS AND RESULTS

The clinical features, diagnoses, treatments and outcomes of MCS-treated patients in refractory cardiogenic shock secondary to fulminant GCM admitted to eight French intensive care units (2002-2016) were analysed. We also conducted a systematic review of this topic. Thirteen patients (median age 44 [range 21-76]years, Simplified Acute Physiology Score II 55 [40-79]) in severe cardiogenic shock (median [range] left ventricular ejection fraction 15% [15-35%] and blood lactate 4 mmol/L) were placed on MCS 4 [0-28]days after hospital admission. Severe arrhythmic disturbances were frequent (77%), with six (46%) patients experiencing an electrical storm prior to MCS. Venoarterial extracorporeal membrane oxygenation was the first MCS option for 11 (85%) patients. GCM was diagnosed in five (38%) patients before transplant or death and treated with immunosuppressants; infections were the main complication (80%). Four patients died on MCS and no patient presented long-term survival free from heart transplant (nine patients, 69%). All transplanted patients were alive 1year later and no GCM recurrence was reported after median follow-up of 42 [12-145]months.

CONCLUSION

Outcomes of fulminant GCMs may differ from those of milder forms. In this context, heart transplant might likely be the only long-term survival option.

Therapeutic implications of a combined diagnostic workup including endomyocardial biopsy in an all-comer population of patients with heart failure: a retrospective analysis

BACKGROUND

Aetiology of heart failure (HF) often remains obscure. We therefore evaluated the usefulness of a combined diagnostic approach including cardiac magnetic resonance imaging (CMRI) and endomyocardial biopsy (EMB) to assess the cause of unexplained cardiomyopathy underlying HF.

METHODS AND RESULTS

We retrospectively investigated 100 consecutive patients (36% women, mean age 53.6 ± 18.8 years) presenting with unexplained cardiomyopathy (HF with reduced ejection fraction or left ventricular hypertrophy; excluding ischaemic and valvular heart disease; left ventricular ejection fraction 31.6 ± 13.9%, Left ventricular end-diastolic pressure 18.2 ± 9.3 mmHg, heart rate 89 ± 26.6 b.p.m.; mean ± SEM) at the University Medical Center Mainz. We performed electrocardiography, echocardiography, CMRI, and cardiac catheterization with EMB analysed at a Food and Drug Administration-approved reference centre in 100%, 94%, 69%, and 100% of patients, respectively. On the basis of CMRI findings, electrocardiography, echocardiography, and medical history, the exact cause of cardiomyopathy remained uncertain in 37 of 69 cases (53.6%). In EMB, 25% of patients had viral replication, 23% had inflammation defined as lymphocytic infiltrations without active virus replication, 1% had giant cell myocarditis, and 1% had eosinophilic myocarditis. After diagnostic workup including EMB findings, the cause of cardiomyopathy remained unidentified in 14% of the cases, classified as idiopathic dilated cardiomyopathy or hypertrophic cardiomyopathy in 10% or 4%, respectively. EMB helped to discuss a causal treatment strategy of HF involving immunosuppression or antiviral treatment in 53% of patients, which was opted for in 12% of the patients.

CONCLUSIONS

A comprehensive workup including imaging and EMB in an all-comer population of patients with HF may help physicians to improve diagnostics of unexplained cardiomyopathy in the majority of cases.