Applications of FDG-PET Scan in Arrhythmic Myocarditis

Hybrid cardiovascular imaging. A clinical consensus statement of the european association of nuclear medicine (EANM) and the european association of cardiovascular imaging (EACVI) of the ESC

Hybrid imaging consists of a combination of two or more imaging modalities, which equally contribute to image information. To date, hybrid cardiovascular imaging can be performed by either merging images acquired on different scanners, or with truly hybrid PET/CT and PET/MR scanners. The European Association of Nuclear Medicine (EANM), and the European Association of Cardiovascular Imaging (EACVI) of the European Society of Cardiology (ESC) aim to review clinical situations that may benefit from the use of hybrid cardiac imaging and provide advice on acquisition protocols providing the most relevant information to reach diagnosis in various clinical situations.

Hot Phases Cardiomyopathy: Pathophysiology, Diagnostic Challenges, and Emerging Therapies

PURPOSE OF REVIEW

Hot phases are a challenging clinical presentation in arrhythmogenic cardiomyopathy (ACM), marked by acute chest pain and elevated cardiac troponins in the absence of obstructive coronary disease. These episodes manifest as myocarditis and primarily affect young patients, contributing to a heightened risk of life-threatening arrhythmias and potential disease progression. This review aims to synthesize recent research on the pathophysiology, diagnostic challenges, and therapeutic management of hot phases in ACM.

RECENT FINDINGS

Hot phases have been linked to genetic mutations, particularly in desmosomal proteins such as Desmoplakin (DSP). Diagnostic challenges include differentiating hot phases from isolated acute myocarditis, through identification of red flags and a multimodal approach, including CMR, FDG-PET, endomyocardial biopsy and genetic testing. Emerging therapies, such as immunosuppressive and anti-inflammatory treatments, show promise in managing hot-phase episodes. Hot phases in ACM present a significant risk for arrhythmias and disease progression, necessitating a comprehensive diagnostic and therapeutic management. A multimodal diagnostic approach is essential for accurate diagnosis, but further research is needed to refine these strategies and improve prognosis for affected patients.

Can FDG PET Serve as a Clinically Relevant Tool for Detecting Active Non-sarcoidotic Myocarditis?

The diagnostic work-up for myocarditis largely depends on non-invasive imaging because of the low yield of endomyocardial biopsy. In addition, differentiation among possible impressions is essential because of its non-specific clinical presentations. This ambiguity has led to the predominant use of cardiac magnetic resonance imaging techniques in the management of myocarditis, particularly during the global pandemic. Despite the unique ability of F-18 fluorodeoxyglucose positron emission tomography to visualize and quantify active myocardial inflammation, which has been well established in cardiac sarcoidosis, its diagnostic contribution in non-sarcoidotic myocarditis remains uncertain. This article reviews the current evidence on the non-invasive imaging diagnosis of non-sarcoidotic myocarditis and discusses the potential role of F-18 fluorodeoxyglucose positron emission tomography as a clinically relevant imaging tool.

Atrioventricular Block in the Setting of Immune Myocarditis: A Pragmatic Approach to Diagnosis and Treatment

Immunotherapy has revolutionized cancer treatment in the last decade and has significantly improved patient survival. However, immunotherapy is associated with serious cardiac adverse events including myocarditis and conduction disturbances. In the literature, the mortality rate in patients with immunotherapy-associated myocarditis and complete AV block is reported to be approximately 60%. Current cardio-oncology guidelines provide a series of recommendations for the management of immune myocarditis (IM). However, there is no recommendation on whether or when pacemaker implantation should be performed in the setting of complete AV block associated with myocarditis. This gap in the literature has led to a trend in cardio-oncology practice to implant permanent pacemakers (PPMs) in a significant proportion of patients without waiting for a response to immunosuppressive therapy. However, in a significant proportion of patients undergoing PPM implantation, complete AV block resolves after immunosuppressive therapy. This suggests that in cases of complete AV block in the setting of IM, more robust clues are needed for PPM implantation. This review aims to present algorithms for the management of myocarditis and complete AV block, one of the most lethal complications of immunotherapy, to help fill this gap in the literature.

Imaging for the diagnosis of acute myocarditis: can artificial intelligence improve diagnostic performance?

Myocarditis is a cardiovascular disease characterised by inflammation of the heart muscle which can lead to heart failure. There is heterogeneity in the mode of presentation, underlying aetiologies, and clinical outcome with impact on a wide range of age groups which lead to diagnostic challenges. Cardiovascular magnetic resonance (CMR) is the preferred imaging modality in the diagnostic work-up of those with acute myocarditis. There is a need for systematic analytical approaches to improve diagnosis. Artificial intelligence (AI) and machine learning (ML) are increasingly used in CMR and has been shown to match human diagnostic performance in multiple disease categories. In this review article, we will describe the role of CMR in the diagnosis of acute myocarditis followed by a literature review on the applications of AI and ML to diagnose acute myocarditis. Only a few papers were identified with limitations in cases and control size and a lack of detail regarding cohort characteristics in addition to the absence of relevant cardiovascular disease controls. Furthermore, often CMR datasets did not include contemporary tissue characterisation parameters such as T1 and T2 mapping techniques, which are central to the diagnosis of acute myocarditis. Future work may include the use of explainability tools to enhance our confidence and understanding of the machine learning models with large, better characterised cohorts and clinical context improving the diagnosis of acute 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.

The Role of Multimodality Imaging in Cardiomyopathy

PURPOSE OF REVIEW

There has been increasing use of multimodality imaging in the evaluation of cardiomyopathies.

RECENT FINDINGS

Echocardiography, cardiac magnetic resonance (CMR), cardiac nuclear imaging, and cardiac computed tomography (CCT) play an important role in the diagnosis, risk stratification, and management of patients with cardiomyopathies. Echocardiography is essential in the initial assessment of suspected cardiomyopathy, but a multimodality approach can improve diagnostics and management. CMR allows for accurate measurement of volumes and function, and can easily detect unique pathologic structures. In addition, contrast imaging and parametric mapping enable the characterization of tissue features such as scar, edema, infiltration, and deposition. In non-ischemic cardiomyopathies, metabolic and molecular nuclear imaging is used to diagnose rare but life-threatening conditions such amyloidosis and sarcoidosis. There is an expanding use of CCT for planning electrophysiology procedures such as cardioversion, ablations, and device placement. Furthermore, CCT can evaluate for complications associated with advanced heart failure therapies such as cardiac transplant and mechanical support devices. Innovations in multimodality cardiac imaging should lead to increased volumes and better outcomes.

Advances in the diagnosis of myocarditis in idiopathic inflammatory myopathies: an overview of diagnostic tests

Cardiac involvement in idiopathic inflammatory myopathies (IIM) purports to worse clinical outcomes, and therefore early identification is important. Research has focused on blood biomarkers and basic investigations such as ECG and echocardiography, which have the advantage of wide availability and low cost but are limited in their sensitivity and specificity. Imaging the myocardium to directly look for inflammation and scarring has therefore been explored, with a number of new methods for doing this gaining wider research interest and clinical availability. Cardiovascular magnetic resonance (CMR) with contemporary multiparametric mapping techniques and late gadolinium enhancement imaging, is an extremely valuable and increasingly used non-invasive imaging modality for the diagnosis of myocarditis. The recently updated CMR-based Lake Louise Criteria for the diagnosis of myocarditis incorporate the newer T1 and T2 mapping techniques, which have greatly improved the diagnostic accuracy for IIM myocarditis.18F-FDG-PET/CT is a well-utilized imaging modality in the diagnosis of malignancies in IIM, and it also has a role for the diagnosis of myocarditis in multiple systemic inflammatory diseases. Endomyocardial biopsy, however, remains the gold standard technique for the diagnosis of myocarditis and is necessary for the diagnosis of specific cases of myocarditis. This article provides an overview of the important tests and imaging modalities that clinicians should consider when faced with an IIM patient with potential myocarditis.

Management of patients with an electrical storm or clustered ventricular arrhythmias: a clinical consensus statement of the European Heart Rhythm Association of the ESC-endorsed by the Asia-Pacific Heart Rhythm Society, Heart Rhythm Society, and Latin-American Heart Rhythm Society

Electrical storm (ES) is a state of electrical instability, manifesting as recurrent ventricular arrhythmias (VAs) over a short period of time (three or more episodes of sustained VA within 24 h, separated by at least 5 min, requiring termination by an intervention). The clinical presentation can vary, but ES is usually a cardiac emergency. Electrical storm mainly affects patients with structural or primary electrical heart disease, often with an implantable cardioverter-defibrillator (ICD). Management of ES requires a multi-faceted approach and the involvement of multi-disciplinary teams, but despite advanced treatment and often invasive procedures, it is associated with high morbidity and mortality. With an ageing population, longer survival of heart failure patients, and an increasing number of patients with ICD, the incidence of ES is expected to increase. This European Heart Rhythm Association clinical consensus statement focuses on pathophysiology, clinical presentation, diagnostic evaluation, and acute and long-term management of patients presenting with ES or clustered VA.

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.

Twenty-five years of research in cardiac imaging in electrophysiology procedures for atrial and ventricular arrhythmias

Catheter ablation is nowadays considered the treatment of choice for numerous cardiac arrhythmias in different clinical scenarios. Fluoroscopy has traditionally been the primary imaging modality for catheter ablation, providing real-time visualization of catheter navigation. However, its limitations, such as inadequate soft tissue visualization and exposure to ionizing radiation, have prompted the integration of alternative imaging modalities. Over the years, advancements in imaging techniques have played a pivotal role in enhancing the safety, efficacy, and efficiency of catheter ablation procedures. This manuscript aims to explore the utility of imaging, including electroanatomical mapping, cardiac computed tomography, echocardiography, cardiac magnetic resonance, and nuclear cardiology exams, in helping electrophysiology procedures. These techniques enable accurate anatomical guidance, identification of critical structures and substrates, and real-time monitoring of complications, ultimately enhancing procedural safety and success rates. Incorporating advanced imaging technologies into routine clinical practice has the potential to further improve clinical outcomes of catheter ablation procedures and pave the way for more personalized and precise ablation therapies in the future.

Multimodal Detection and Targeting of Biopsy-Proven Myocardial Inflammation in Genetic Cardiomyopathies: A Pilot Report

The authors present a clinical report focused on the overlap between myocarditis and genetic cardiomyopathies of the dilated and arrhythmogenic spectrum. Our cohort was composed of 25 patients undergoing extensive baseline characterization and prospective reassessment by a dedicated multidisciplinary disease unit during a median follow-up of 69 months. We showed that the use of multimodal imaging allowed both discrimination of specific genotypes and identification of myocardial inflammation proven using endomyocardial biopsy. In addition, we showed that the use of immunomodulatory therapy was beneficial for most patients.

Myocardial Inflammation as a Manifestation of Genetic Cardiomyopathies: From Bedside to the Bench

Over recent years, preclinical and clinical evidence has implicated myocardial inflammation (M-Infl) in the pathophysiology and phenotypes of traditionally genetic cardiomyopathies. M-Infl resembling myocarditis on imaging and histology occurs frequently as a clinical manifestation of classically genetic cardiac diseases, including dilated and arrhythmogenic cardiomyopathy. The emerging role of M-Infl in disease pathophysiology is leading to the identification of druggable targets for molecular treatment of the inflammatory process and a new paradigm in the field of cardiomyopathies. Cardiomyopathies constitute a leading cause of heart failure and arrhythmic sudden death in the young population. The aim of this review is to present, from bedside to bench, the current state of the art about the genetic basis of M-Infl in nonischemic cardiomyopathies of the dilated and arrhythmogenic spectrum in order to prompt future research towards the identification of novel mechanisms and treatment targets, with the ultimate goal of lowering disease morbidity and mortality.

Cardiovascular magnetic resonance for evaluation of cardiac involvement in COVID-19: recommendations by the Society for Cardiovascular Magnetic Resonance

Coronavirus disease 2019 (COVID-19) is an ongoing global pandemic that has affected nearly 600 million people to date across the world. While COVID-19 is primarily a respiratory illness, cardiac injury is also known to occur. Cardiovascular magnetic resonance (CMR) imaging is uniquely capable of characterizing myocardial tissue properties in-vivo, enabling insights into the pattern and degree of cardiac injury. The reported prevalence of myocardial involvement identified by CMR in the context of COVID-19 infection among previously hospitalized patients ranges from 26 to 60%. Variations in the reported prevalence of myocardial involvement may result from differing patient populations (e.g. differences in severity of illness) and the varying intervals between acute infection and CMR evaluation. Standardized methodologies in image acquisition, analysis, interpretation, and reporting of CMR abnormalities across would likely improve concordance between studies. This consensus document by the Society for Cardiovascular Magnetic Resonance (SCMR) provides recommendations on CMR imaging and reporting metrics towards the goal of improved standardization and uniform data acquisition and analytic approaches when performing CMR in patients with COVID-19 infection.

Multimodality Imaging in Arrhythmogenic Left Ventricular Cardiomyopathy

The term arrhythmogenic cardiomyopathy (ACM) describes a large spectrum of myocardial diseases characterized by progressive fibrotic or fibrofatty replacement, which gives the substrate for the occurrence of ventricular tachyarrhythmias and the development of ventricular dysfunction. This condition may exclusively affect the left ventricle, leading to the introduction of the term arrhythmogenic left ventricular cardiomyopathy (ALVC). The clinical features of ALVC are progressive fibrotic replacement with the absence or mild dilation of the LV and the occurrence of ventricular arrhythmias within the left ventricle. In 2019, the diagnostic criteria for the diagnosis of ALVC, based on family history and clinical, electrocardiographic, and imaging features, have been proposed. However, since the significant clinical and imaging overlap with other cardiac diseases, genetic testing with the demonstration of a pathogenic variant in an ACM-related gene is required for diagnostic confirmation. In ALVC, the multimodality imaging approach comprises different imaging techniques, such as echocardiography, cardiac magnetic resonance, and cardiac nuclear imaging. It provides essential information for the diagnosis, differential diagnosis, sudden cardiac death risk stratification, and management purposes. This review aims to elucidate the current role of the different multimodality imaging techniques in patients with ALVC.

Inflammation on Endomyocardial Biopsy Predicts Risk of MACE in Undefined Left Ventricular Arrhythmogenic Cardiomyopathy

BACKGROUND

Predictors of major adverse cardiovascular events (MACE) in patients with undefined left ventricular arrhythmogenic cardiomyopathy (ULVACM) have not been described.

OBJECTIVES

The purpose of this study was to investigate the prognostic value of genetic testing and histology in a cohort of ULVACM patients.

METHODS

We identified 313 patients with ULVACM defined by new-onset ventricular arrhythmia (VA), nonischemic pattern of late gadolinium enhancement limited to the left ventricle (LV), and no severe dilated cardiomyopathy (LV ejection fraction ≥40%) from a retrospective multicenter registry. Patients undergoing next generation sequencing (NGS) for cardiomyopathy genes and endomyocardial biopsy (EMB) were compared with subjects without these studies. The primary endpoint was the occurrence of MACE, defined as the composite of cardiac death, heart transplantation, and malignant VA (ventricular tachycardia, ventricular fibrillation, appropriate implantable cardioverter-defibrillator treatment), at 60 months after clinical presentation.

RESULTS

Of the whole cohort (age 46 ± 14 years, 63% men, LV ejection fraction 55% ± 7%), 160 (51%) and 198 patients (63%), respectively, underwent NGS and EMB. NGS identified pathogenic or likely-pathogenic cardiomyopathy variants (pathogenic variants/likely pathogenic variants) in 25 of 160 cases (16%). EMB showed active myocardial inflammation (AM) in 102 of 198 patients (52%), 47 of whom (46%) received immunosuppressive therapy. After 58-month median follow-up, 93 of 313 patients (30%) experienced MACE. On multivariable analysis, presentation with malignant VA and EMB-proven AM were positively associated with the primary endpoint (HR: 2.8; 95% CI: 1.4-5.5; P = 0.003; and HR: 3.9; 95% CI: 1.9-7.5; P < 0.001, respectively), whereas immunosuppressive therapy showed a reverse association with MACE at 60 months (HR: 0.10; 95% CI: 0.05-0.40; P < 0.001).

CONCLUSIONS

Presentation with malignant VA or AM associates with MACE in ULVACM patients.

Exercise Stress Test Late after Arrhythmic versus Nonarrhythmic Presentation of Myocarditis

Background. Exercise stress test (EST) has been scarcely investigated in patients with arrhythmic myocarditis. Objectives. To report the results of EST late after myocarditis with arrhythmic vs. nonarrhythmic presentation. Methods. We enrolled consecutive adult patients with EST performed at least six months after acute myocarditis was diagnosed using gold-standard techniques. Patients with ventricular arrhythmia (VA) at presentation were compared with the nonarrhythmic group. Adverse events occurring during follow-up after EST included cardiac death, disease-related rehospitalization, malignant VA, and proven active myocarditis. Results. The study cohort was composed of 128 patients (age 41 ± 9 y, 70% males) undergoing EST after myocarditis. Of them, 64 (50%) had arrhythmic presentation. EST was performed after 15 ± 4 months from initial diagnosis, and was conducted on betablockers in 75 cases (59%). During EST, VA were more common in the arrhythmic group (43 vs. 4, p < 0.001), whereas signs and symptoms of ischemia were more prevalent in the nonarrhythmic one (6 vs. 1, p = 0.115). By 58-month mean follow-up, 52 patients (41%) experienced adverse events, with a greater prevalence among arrhythmic patients (39 vs. 13, p < 0.001). As documented both in the arrhythmic and nonarrhythmic subgroups, patients had greater prevalence of adverse events following a positive EST (40/54 vs. 12/74 with negative EST, p < 0.001). Electrocardiographic features of VA during EST correlated with the subsequent inflammatory restaging of myocarditis. Nonarrhythmic patients with uneventful EST both on- and off-treatment were free from subsequent adverse events. Conclusions. Late after the arrhythmic presentation of myocarditis, EST was frequently associated with recurrent VA. In both arrhythmic and nonarrhythmic myocarditis, EST abnormalities correlated with subsequent adverse outcomes.

Arrhythmogenic Cardiomyopathy: One, None and a Hundred Thousand Diseases

According to the most recent expert consensus statement, arrhythmogenic cardiomyopathy (AC) is defined as an arrhythmogenic heart muscle disorder, not explained by ischemic, hypertensive, or valvular heart disease, presenting clinically as symptoms or documentation of atrial fibrillation, conduction disease, and/or right ventricular (RV) and/or left ventricular (LV) arrhythmia [...].