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Myocarditis, an inflammatory disease of heart muscle, is an important cause of dilated cardiomyopathy worldwide. Viral infection is also an important cause of myocarditis, and the spectrum of viruses known to cause myocarditis has changed in the past 2 decades. Several new diagnostic methods, such as cardiac magnetic resonance imaging, are useful for diagnosing myocarditis. Endomyocardial biopsy may be used for patients with acute dilated cardiomyopathy associated with hemodynamic compromise, those with life-threatening arrhythmia, and those whose condition does not respond to conventional supportive therapy. Important prognostic variables include the degree of left and right ventricular dysfunction, heart block, and specific histopathological forms of myocarditis. We review diagnostic and therapeutic strategies for the treatment of viral myocarditis. English-language publications in PubMed and references from relevant articles published between January 1, 1985, and August 5, 2008, were analyzed. Main keywords searched were myocarditis, dilated cardiomyopathy, endomyocardial biopsy, cardiac magnetic resonance imaging, and immunotherapy. [ABSTRACT FROM AUTHOR]

Introduction: Extracellular vesicles (EVs) can potently inhibit inflammation yet there is a lack of understanding about the impact of donor characteristics on the efficacy of EVs. The goal of this study was to determine whether the sex and age of donor platelet-derived EVs (PEV) affected their ability to inhibit viral myocarditis., Methods: PEV, isolated from men and women of all ages, was compared to PEV obtained from women under 50 years of age, which we termed premenopausal PEV (pmPEV). Because of the protective effect of estrogen against myocardial inflammation, we hypothesized that pmPEV would be more effective than PEV at inhibiting myocarditis. We injected PEV, pmPEV, or vehicle control in a mouse model of viral myocarditis and examined histology, gene expression, protein profiles, and performed proteome and microRNA (miR) sequencing of EVs., Results: We found that both PEV and pmPEV significantly inhibited myocarditis; however, PEV was more effective, which was confirmed by a greater reduction of inflammatory cells and proinflammatory and profibrotic markers determined using gene expression and immunohistochemistry. Proteome and miR sequencing of EVs revealed that PEV miRs specifically targeted antiviral, Toll-like receptor (TLR)4, and inflammasome pathways known to contribute to myocarditis while pmPEV contained general immunoregulatory miRs., Discussion: These differences in EV content corresponded to the differing anti-inflammatory effects of the two types of EVs on viral myocarditis., Competing Interests: AB, PS, and AT, along with Mayo Clinic have ownership interest in Rion, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2025 Beetler, Giresi, Di Florio, Fliess, McCabe, Watkins, Xu, Auda, Bruno, Whelan, Kocsis, Edenfield, Walker, Macomb, Keegan, Jain, Morales-Lara, Chekuri, Hill, Farres, Wolfram, Behfar, Stalboerger, Terzic, Cooper and Fairweather.)

Background: Myocarditis is an inflammation of the heart muscle most often caused by viral infections. Sex differences in the immune response during myocarditis have been well described but upstream mechanisms in the heart that might influence sex differences in disease are not completely understood., Methods: Male and female BALB/c wild type mice received an intraperitoneal injection of heart-passaged coxsackievirus B3 (CVB3) or vehicle control. Bulk-tissue RNA-sequencing was conducted to better understand sex differences in CVB3 myocarditis. We performed enrichment analysis and functional validation to understand sex differences in the transcriptional landscape of myocarditis and identify factors that might drive sex differences in myocarditis., Results: As expected, the hearts of male and female mice with myocarditis were significantly enriched for pathways related to an innate and adaptive immune response compared to uninfected controls. Unique to this study, we found that males were enriched for inflammatory pathways and gene changes that suggested worse mitochondrial electron transport function while females were enriched for pathways related to mitochondrial homeostasis. Mitochondria isolated from the heart of males were confirmed to have worse mitochondrial respiration than females during myocarditis. Unbiased TRANSFAC analysis identified estrogen-related receptor alpha (ERRα) as a transcription factor that may mediate sex differences in mitochondrial function during myocarditis. Transcript and protein levels of ERRα were confirmed as elevated in females with myocarditis compared to males. Differential binding analysis from chromatin immunoprecipitation (ChIP) sequencing confirmed that ERRα bound highly to select predicted respiratory chain genes in females more than males during myocarditis., Conclusions: Females with viral myocarditis regulate mitochondrial homeostasis by upregulating master regulators of mitochondrial transcription including ERRα., Competing Interests: Declarations. Ethics approval and consent to participate: Mice were used in accordance with the recommendations in the Guide for the Care and Use the Laboratory Animals of the National Institutes of Health (NIH) and approval obtained from the Animal Care and Use Committee at Mayo Clinic Florida for all procedures (IACUC# A00003984). Mice were maintained under pathogen-free conditions in the animal facility at Mayo Clinic Florida and mice were sacrificed according to the Guide for the Care and Use of Laboratory Animals of the NIH. Consent for publication: Not applicable. Competing interests: The authors declare that they have no competing interests., (© 2024. The Author(s).)

Objective: Evaluate the relationship of cathepsin-D (CD) on disease severity and clinical outcomes for women with peripartum cardiomyopathy., Background: Cathepsin-D is a protease released during oxidative stress that cleaves prolactin (PRL) generating a 16 kDa fragment that is pro-apoptotic, anti-angiogenic, and has been implicated in the pathogenesis of peripartum cardiomyopathy (PPCM)., Methods: In 99 women with newly diagnosed PPCM enrolled in the Investigation in Pregnancy Associated Cardiomyopathy (IPAC) study, CD levels were assessed by ELISA from serum obtained at study entry. Left ventricular ejection fraction (LVEF) was assessed by echocardiography at entry, 6, and 12-months. CD levels were compared to healthy PP and non-PP controls. Survival free from major cardiovascular events (death, transplantation, or left ventricular assist device) was determined up to 12 months post-partum (PP)., Results: Mean age was 30 ± 6 years, with a baseline LVEF of 34 % ± 10. Cathepsin-D levels were higher in PPCM women (278 ± 114 ng/ml) than in healthy PP (190 ± 74, p  = 0.02) and healthy non-PP controls (136 ± 79, p  < 0.001). There was no association of CD with age, breastfeeding status, or time from delivery to the presentation. Cathepsin-D levels were higher in women with higher New York Heart Association (NYHA) functional class ( p  = 0.001). Higher tertiles of CD levels were associated with lower event-free survival ( p  = 0.008)., Conclusions: In this prospective cohort of women with PPCM, higher CD levels at the time of diagnosis were associated with worse symptoms, less recovery of LVEF, and worse clinical outcomes. Circulating CD may contribute to the development of PPCM and influence disease severity, myocardial recovery, and clinical outcomes., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Background: Black women with peripartum cardiomyopathy (PPCM) have a higher prevalence of hypertensive disorders of pregnancy (HDP) and worse clinical outcomes compared with non-Black women. We examined the impact of HDP on myocardial recovery in Black women with PPCM., Methods: A total of 100 women were enrolled into the Investigation in Pregnancy Associated Cardiomyopathy (IPAC) study. Left ventricular ejection fraction (LVEF) was assessed by echocardiography at entry, 6, and 12-months post-partum (PP). Women were followed for 12 months postpartum and outcomes including persistent cardiomyopathy (LVEF ≤35%), left ventricular assist device, (LVAD), cardiac transplantation, or death were examined in subsets based on race and the presence of HDP., Results: Black women with HDP were more likely to present earlier compared to Black women without HDP (days PP HDP: 34 ± 21 vs 54 ± 27 days, P = .03). There was no difference in LVEF at study entry for Black women based on HDP, but better recovery with HDP at 6 (HDP: 52 ± 11% vs no HDP: 40 ± 14%, P = .03) and 12-months (HDP:53 ± 10% vs no HDP:40 ± 16%, P = .02). At 12-months, Black women overall had a lower LVEF than non-Black women (P < .001), driven by less recovery in Black women without HDP compared to non-Black women (P < .001). In contrast, Black women with HDP had a similar LVEF at 12 months compared to non-Black women (P = .56)., Conclusions: In women with PPCM, poorer outcomes evident in Black women were driven by women without a history of HDP. In Black women, a history of HDP was associated with earlier presentation and recovery which was comparable to non-Black women., Competing Interests: Conflict of interest AEJ has received honoraria from Sanofi and Edwards Lifesciences. All other authors have no Conflicts of Interest to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Myocarditis is an inflammatory injury of the myocardium. Viral infections are the most common etiology, but less frequently, inflammatory myocardial injury can result from systemic autoimmune diseases. We present the first reported case of myocarditis in a patient with anti-IgLON5 disease., Competing Interests: The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2024 The Authors.)

The clinical and imaging features of cardiac sarcoidosis (CS) and giant cell myocarditis (GCM) are occasionally indistinguishable. This is a case of heart block and ventricular tachycardia where cardiac MRI, fluorodeoxyglucose positron emission tomography (FDG-PET) and biopsy revealed intermediate clinicohistologic phenotype between CS and GCM. This highlights gaps in the management of overlap conditions., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Sharma et al.)

Background: Many patients diagnosed with COVID-19 have persistent cardiovascular symptoms, but whether this represents a true cardiac process is unclear. This study assessed whether symptoms associated with long COVID among patients referred for cardiovascular evaluation are associated with objective abnormalities on cardiac testing to explain their clinical presentation., Methods: A retrospective cohort study of 40,462 unique patients diagnosed with COVID-19 at our tertiary referral was conducted and identified 363 patients with persistent cardiovascular symptoms a minimum of 4 weeks after polymerase chain reaction confirmed COVID-19 infection. Patients had no cardiovascular symptoms prior to COVID-19 infection. Each patient was referred for cardiovascular evaluation at a tertiary referral center. The incidence and etiology of abnormalities on cardiovascular testing among patients with long COVID symptoms are reported here. The cohort was subsequently divided into 3 categories based on the dominant circulating severe acute respiratory syndrome coronavirus 2 variant at the time of initial infection for further analysis., Results: Among 40,462 unique patients diagnosed with COVID-19 at our tertiary referral center from April 2020 to March 2022, 363 (0.9%) patients with long COVID were evaluated by Cardiology for possible cardiac sequelae from COVID and formed the main study cohort. Of these, 229 (63%) were vaccinated and 47 (12.9%) had severe initial infection, receiving inpatient treatment for COVID prior to developing long COVID symptoms. Symptoms were associated with a cardiac cause in 85 (23.4%), of which 52 (14.3%) were attributed to COVID; 39 (10.7%) with new cardiac disease from COVID, and 13 (3.6%) to worsening of pre-existing cardiac disease after COVID infection. The median troponin change in 45 patients with troponin measurements within 4 weeks of acute infection was +4 ng/dL (9 to 13 ng/dL). Among the total cohort with long COVID, 83.7% were diagnosed during the pre-Delta phase, 13.2% during the Delta phase, and 3.1% during the Omicron phase of the pandemic. There were 6 cases of myocarditis, 11 rhythm disorders, 8 cases of pericarditis, 5 suspected cases of endothelial dysfunction, and 33 cases of autonomic dysfunction., Conclusion: This pragmatic retrospective cohort study suggests that patients with long COVID referred for cardiovascular evaluation infrequently have new, objective cardiovascular disease to explain their clinical presentation. A multidisciplinary, patient-centered approach is warranted for symptom management along with conservative use of diagnostic testing., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Myocarditis is an inflammatory disease of the myocardium secondary to infectious and noninfectious insults. The most feared consequence of myocarditis is sudden cardiac death owing to electrical instability and arrhythmia. Typical presenting symptoms include chest pain, dyspnea, palpitations and/or heart failure. Diagnosis is usually made with history, electrocardiogram, biomarkers, echocardiogram, and cardiac MRI (CMR). Application of the Lake Louise criteria to CMR results can help identify cases of myocarditis. Treatment is usually supportive with medical therapy, and patients are recommended to abstain from exercise for 3 to 6 months. Exercise restrictions may be lifted after normalization on follow-up testing., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Competing Interests: Disclosures Dr Cooper receives consulting fees from Bristol Meyers Squibb, CardiolRx, Moderna, and the Chan Zuckerberg Rare as One Foundation and has equity ownership in Stromal Therapeutics, LLC.

Myocarditis is typically caused by viral infections, but most cases are thought to be subclinical. Echocardiography is often used for initial assessment of myocarditis patients but is poor at detecting subtle changes in cardiac dysfunction. Cardiac strain, such as global longitudinal strain (GLS) and global circumferential strain (GCS), represents an increasingly used set of measurements which can detect these subtle changes. Using a murine model of coxsackievirus B3 myocarditis, we characterized functional changes in the heart using echocardiography during myocarditis and by sex. We found that 2D GLS, 4D mode, and 4D strains detected a significant reduction in ejection fraction and GLS during myocarditis compared to baseline and in males compared to females. Furthermore, worse GLS correlated to increased levels of CD45 + , CD11b+, and CD3 + immune cells. Our findings closely resemble published reports of GLS in patients with myocarditis indicating the usefulness of this animal model for translational studies of myocarditis., Competing Interests: The authors declare no conflict of interest., (© 2023 The Authors.)

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., Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Extracellular vesicles (EVs) are released from all cells in the body, forming an important intercellular communication network that contributes to health and disease. The contents of EVs are cell source-specific, inducing distinct signaling responses in recipient cells. The specificity of EVs and their accumulation in fluid spaces that are accessible for liquid biopsies make them highly attractive as potential biomarkers and therapies for disease. The duality of EVs as favorable (therapeutic) or unfavorable (pathological) messengers is context dependent and remains to be fully determined in homeostasis and various disease states. This review describes the use of EVs as biomarkers, drug delivery vehicles, and regenerative therapeutics, highlighting examples involving viral infections, cancer, and neurological diseases. There is growing interest to provide personalized therapy based on individual patient and disease characteristics. Increasing evidence suggests that EV biomarkers and therapeutic approaches are ideal for personalized medicine due to the diversity and multifunctionality of EVs., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest. The work has been performed with partial support from National Institutes of Health (NIH) grant TL1 TR002380 (to DJB, DND), U54 TR002377 (to DJB, DND, DF), National Institute of Allergy and Infectious Disease (NIAID) grants R21 AI145356, R21 AI154927 (to DF), R21 AI152318 (to JW and DF), and R21 AI163302 (to KAB), National Institute on Aging (NIA) grants R01 AG072719, R01 AG054199, R01 AG067763, R01 AG066429, R01 AG054672 (to TI), National Heart, Lung and Blood Institute (NHLBI) grant R01 HL164520 (to DF), American Heart Association grant 20TPA35490415 (to DF), a Mayo Clinic Team Science Award (to DF), the Mayo Clinic Center for Regenerative Medicine in Florida (to JW and DF), the University of Queensland grant (to JW), and Ionis Pharmaceuticals Ion-ARPA Operation Payload Delivery grant (to JW). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Viral infections are a leading cause of myocarditis and pericarditis worldwide, conditions that frequently coexist. Myocarditis and pericarditis were some of the early comorbidities associated with SARS-CoV-2 infection and COVID-19. Many epidemiologic studies have been conducted since that time concluding that SARS-CoV-2 increased the incidence of myocarditis/pericarditis at least 15× over pre-COVID levels although the condition remains rare. The incidence of myocarditis pre-COVID was reported at 1 to 10 cases/100 000 individuals and with COVID ranging from 150 to 4000 cases/100 000 individuals. Before COVID-19, some vaccines were reported to cause myocarditis and pericarditis in rare cases, but the use of novel mRNA platforms led to a higher number of reported cases than with previous platforms providing new insight into potential pathogenic mechanisms. The incidence of COVID-19 vaccine-associated myocarditis/pericarditis covers a large range depending on the vaccine platform, age, and sex examined. Importantly, the findings highlight that myocarditis occurs predominantly in male patients aged 12 to 40 years regardless of whether the cause was due to a virus-like SARS-CoV-2 or associated with a vaccine-a demographic that has been reported before COVID-19. This review discusses findings from COVID-19 and COVID-19 vaccine-associated myocarditis and pericarditis considering the known symptoms, diagnosis, management, treatment, and pathogenesis of disease that has been gleaned from clinical research and animal models. Sex differences in the immune response to COVID-19 are discussed, and theories for how mRNA vaccines could lead to myocarditis/pericarditis are proposed. Additionally, gaps in our understanding that need further research are raised., Competing Interests: Disclosures D. Fairweather is on the advisory board of Cytokinetics. B. Heidecker is an inventor on patents that use RNA for diagnosis of myocarditis. L.T. Cooper has served as a consultant for myocarditis to Bristol Meyers Squibb, CardiolRx, Kiniksa, and Moderna. He has equity ownership in Stromal Therapeutics, Inc. The other authors report no conflicts.

In the past decade there has been a growing interest in understanding sex and gender differences in myocarditis and dilated cardiomyopathy (DCM), and the purpose of this review is to provide an update on this topic including epidemiology, pathogenesis and clinical presentation, diagnosis and management. Recently, many clinical studies have been conducted examining sex differences in myocarditis. Studies consistently report that myocarditis occurs more often in men than women with a sex ratio ranging from 1:2-4 female to male. Studies reveal that DCM also has a sex ratio of around 1:3 women to men and this is also true for familial/genetic forms of DCM. Animal models have demonstrated that DCM develops after myocarditis in susceptible mouse strains and evidence exists for this progress clinically as well. A consistent finding is that myocarditis occurs primarily in men under 50 years of age, but in women after age 50 or post-menopause. In contrast, DCM typically occurs after age 50, although the age that post-myocarditis DCM occurs has not been investigated. In a small study, more men with myocarditis presented with symptoms of chest pain while women presented with dyspnea. Men with myocarditis have been found to have higher levels of heart failure biomarkers soluble ST2, creatine kinase, myoglobin and T helper 17-associated cytokines while women develop a better regulatory immune response. Studies of the pathogenesis of disease have found that Toll-like receptor (TLR)2 and TLR4 signaling pathways play a central role in increasing inflammation during myocarditis and in promoting remodeling and fibrosis that leads to DCM, and all of these pathways are elevated in males. Management of myocarditis follows heart failure guidelines and there are currently no disease-specific therapies. Research on standard heart failure medications reveal important sex differences. Overall, many advances in our understanding of the effect of biologic sex on myocarditis and DCM have occurred over the past decade, but many gaps in our understanding remain. A better understanding of sex and gender effects are needed to develop disease-targeted and individualized medicine approaches in the future., Competing Interests: DF is on the advisory board of Cytokinetics. BH is inventor on patents that use RNA for diagnosis of myocarditis. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Fairweather, Beetler, Musigk, Heidecker, Lyle, Cooper and Bruno.)

Myocarditis is an inflammatory disease of the myocardium secondary to infectious and noninfectious insults. The most feared consequence of myocarditis is sudden cardiac death owing to electrical instability and arrhythmia. Typical presenting symptoms include chest pain, dyspnea, palpitations and/or heart failure. Diagnosis is usually made with history, electrocardiogram, biomarkers, echocardiogram, and cardiac MRI (CMR). Application of the Lake Louise criteria to CMR results can help identify cases of myocarditis. Treatment is usually supportive with medical therapy, and patients are recommended to abstain from exercise for 3 to 6 months. Exercise restrictions may be lifted after normalization on follow-up testing., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Aims: The goal of this study was to determine whether sex and age differences exist for soluble ST2 (sST2) for several cardiovascular diseases (CVDs)., Methods: We examined sST2 levels using an ELISA kit for myocarditis ( n = 303), cardiomyopathy ( n = 293), coronary artery disease (CAD) ( n = 239), myocardial infarct (MI) ( n = 159), and congestive heart failure (CHF) ( n = 286) and compared them to controls that did not have CVDs ( n = 234)., Results: Myocarditis occurred in this study in relatively young patients around age 40 while the other CVDs occurred more often in older individuals around age 60. We observed a sex difference in sST2 by age only in myocarditis patients (men aged 38, women 46, p = 0.0002), but not for other CVDs. Sera sST2 levels were significantly elevated compared to age-matched controls for all CVDs: myocarditis ( p ≤ 0.0001), cardiomyopathy ( p = 0.0009), CAD ( p = 0.03), MI ( p = 0.034), and CHF ( p < 0.0001) driven by elevated sST2 levels in females for all CVDs except myocarditis, which was elevated in both females ( p = 0.002) and males ( p ≤ 0.0001). Sex differences in sST2 levels were found for myocarditis and cardiomyopathy but no other CVDs and were higher in males (myocarditis p = 0.0035; cardiomyopathy p = 0.0047). sST2 levels were higher in women with myocarditis over 50 years of age compared to men ( p = 0.0004) or women under 50 years of age ( p = 0.015). In cardiomyopathy and MI patients, men over 50 had significantly higher levels of sST2 than women ( p = 0.012 and p = 0.043, respectively) but sex and age differences were not detected in other CVDs. However, women with cardiomyopathy that experienced early menopause had higher sST2 levels than those who underwent menopause at a natural age range ( p = 0.02)., Conclusion: We found that sex and age differences in sera sST2 exist for myocarditis, cardiomyopathy, and MI, but were not observed in other CVDs including CAD and CHF. These initial findings in patients with self-reported CVDs indicate that more research is needed into sex and age differences in sST2 levels in individual CVDs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Beetler, Bruno, Di Florio, Douglass, Shrestha, Tschöpe, Cunningham, Krejčí, Bienertová-Vašků, Pankuweit, McNamara, Jeon, van Linthout, Blauwet, Cooper and Fairweather.)

Competing Interests: EA has received a grant from the Italian Ministry of Health (GR-2019–12368506), and is a consultant for Kiniksa and Cytokinetics. LTC has served as a consultant for Moderna, receives grant funding from the National Institutes of Health, consults for Bristol Myers Squibb, Kiniksa, Moderna, and CardiolRX, and is a board member of Stromal Therapeutics.

Background: Tumor necrosis factor (TNF) inhibitors have been used in the treatment of cardiac sarcoidosis, infliximab being the most commonly used. We have previously reported a case of effective treatment of cardiac sarcoidosis using adalimumab., Objective: To describe our experience of using adalimumab in the treatment of cardiac sarcoidosis., Methods: We conducted a retrospective study to evaluate patients with cardiac sarcoidosis who received adalimumab treatment at the University of Illinois Health between 2011 and 2022. The outcome was evaluated by assessing safety, tolerability, and ability to taper systemic corticosteroids therapy following initiation of adalimumab., Results: Seven patients met the inclusion criteria. Clinical responses to adalimumab were universally positive. Corticosteroid therapy was discontinued in five patients and the dose was reduced in two patients. Furthermore, adalimumab was well tolerated, and no adverse events were reported., Conclusion: Adalimumab was safe and well-tolerated in seven patients with cardiac sarcoidosis seen at our medical center and exhibited corticosteroid-sparing effects. Our observation further warrants large prospective studies to evaluate the safety and efficacy of adalimumab in the treatment of cardiac sarcoidosis., Competing Interests: The authors have no conflicts of interest to disclose., (© 2022 The Authors.)

Background: Acute myocarditis is an inflammatory condition that may herald the onset of dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM). We investigated the frequency and clinical consequences of DCM and ACM genetic variants in a population-based cohort of patients with acute myocarditis., Methods: This was a population-based cohort of 336 consecutive patients with acute myocarditis enrolled in London and Maastricht. All participants underwent targeted DNA sequencing for well-characterized cardiomyopathy-associated genes with comparison to healthy controls (n=1053) sequenced on the same platform. Case ascertainment in England was assessed against national hospital admission data. The primary outcome was all-cause mortality., Results: Variants that would be considered pathogenic if found in a patient with DCM or ACM were identified in 8% of myocarditis cases compared with <1% of healthy controls ( P =0.0097). In the London cohort (n=230; median age, 33 years; 84% men), patients were representative of national myocarditis admissions (median age, 32 years; 71% men; 66% case ascertainment), and there was enrichment of rare truncating variants (tv) in ACM-associated genes (3.1% of cases versus 0.4% of controls; odds ratio, 8.2; P =0.001). This was driven predominantly by DSP -tv in patients with normal LV ejection fraction and ventricular arrhythmia. In Maastricht (n=106; median age, 54 years; 61% men), there was enrichment of rare truncating variants in DCM-associated genes, particularly TTN -tv, found in 7% (all with left ventricular ejection fraction <50%) compared with 1% in controls (odds ratio, 3.6; P =0.0116). Across both cohorts over a median of 5.0 years (interquartile range, 3.9-7.8 years), all-cause mortality was 5.4%. Two-thirds of deaths were cardiovascular, attributable to worsening heart failure (92%) or sudden cardiac death (8%). The 5-year mortality risk was 3.3% in genotype-negative patients versus 11.1% for genotype-positive patients ( P adjusted =0.08)., Conclusions: We identified DCM- or ACM-associated genetic variants in 8% of patients with acute myocarditis. This was dominated by the identification of DSP -tv in those with normal left ventricular ejection fraction and TTN -tv in those with reduced left ventricular ejection fraction. Despite differences between cohorts, these variants have clinical implications for treatment, risk stratification, and family screening. Genetic counseling and testing should be considered in patients with acute myocarditis to help reassure the majority while improving the management of those with an underlying genetic variant.

Background: The risk of adverse cardiovascular events in patients with acute myocarditis (AM) and desmosomal gene variants (DGV) remains unknown., Objectives: The purpose of this study was to ascertain the risk of death, ventricular arrhythmias, recurrent myocarditis, and heart failure (main endpoint) in patients with AM and pathogenic or likely pathogenetic DGV., Methods: In a retrospective international study from 23 hospitals, 97 patients were included: 36 with AM and DGV (DGV[+]), 25 with AM and negative gene testing (DGV[-]), and 36 with AM without genetics testing. All patients had troponin elevation plus findings consistent with AM on histology or at cardiac magnetic resonance (CMR). In 86 patients, CMR changes in function and structure were re-assessed at follow-up., Results: In the DGV(+) AM group (88.9% DSP variants), median age was 24 years, 91.7% presented with chest pain, and median left ventricular ejection fraction (LVEF) was 56% on CMR (P = NS vs the other 2 groups). Kaplan-Meier curves demonstrated a higher risk of the main endpoint in DGV(+) AM compared with DGV(-) and without genetics testing patients (62.3% vs 17.5% vs 5.3% at 5 years, respectively; P &lt; 0.0001), driven by myocarditis recurrence and ventricular arrhythmias. At follow-up CMR, a higher number of late gadolinium enhanced segments was found in DGV(+) AM., Conclusions: Patients with AM and evidence of DGV have a higher incidence of adverse cardiovascular events compared with patients with AM without DGV. Further prospective studies are needed to ascertain if genetic testing might improve risk stratification of patients with AM who are considered at low risk., Competing Interests: Funding Support and Author Disclosures Dr Ammirati has received a grant from the Italian Ministry of Health (GR-2019-12368506) and is a consultant for Kiniksa and Cytokinetics. Dr Adler is a consultant for Abbott, Abiomed, AstraZeneca, Endotronix, Ionis, Medtronic, and Novartis; is on the board of directors of Genstem Therapeutics; and is a shareholder of Rocket Pharmaceuticals. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aims: We developed an international registry to examine cardiovascular complications of COVID-19. Methods: A REDCap form was created in March 2020 at Mayo Clinic in collaboration with the International Society of Cardiomyopathy, Myocarditis and Heart Failure (ISCMF) and data were entered from April 2020 through April 2021. Results: Of the 696 patients in the COVID-19 Registry, 411 (59.2%) were male and 283 (40.8%) were female, with a sex ratio of 1.5:1 male to female. In total, 95.5% of the patients were from Japan. The average age was 52 years with 31.5% being >65 years of age. COVID-19 patients with a history of cardiovascular disease (CVD) had more pre-existing conditions including type II diabetes (p < 0.0001), cancer (p = 0.0003), obesity (p = 0.001), and kidney disease (p = 0.001). They also had a greater mortality of 10.1% compared to 1.7% in those without a history of CVD (p < 0.0001). The most common cardiovascular conditions in patients with a history of CVD were hypertension (33.7%), stroke (5.7%) and arrhythmias (5.1%). We found that troponin T, troponin I, brain natriuretic peptide (BNP), N-terminal pro-BNP (NT-proBNP), C-reactive protein (CRP), IL-6 and lambda immunoglobulin free light chains (Ig FLC) were elevated above reference levels in patients with COVID-19. Myocarditis is known to occur mainly in adults under the age of 50, and when we examined biomarkers in patients that were ≤50 years of age and had no history of CVD we found that a majority of patients had elevated levels of troponin T (71.4%), IL-6 (59.5%), creatine kinase/CK-MB (57.1%), D-dimer (57.8%), kappa Ig FLC (75.0%), and lambda Ig FLC (71.4%) suggesting myocardial injury and possible myocarditis. Conclusions: We report the first findings to our knowledge of cardiovascular complications from COVID-19 in the first year of the pandemic in a predominantly Japanese population. Mortality was increased by a history of CVD and pre-existing conditions including type II diabetes, cancer, obesity, and kidney disease. Our findings indicate that even in cases where no abnormalities are found in ECG or ultrasound cardiography that myocardial damage may occur, and cardiovascular and inflammatory biomarkers may be useful for the diagnosis.

Background Sarcoidosis is an inflammatory, noncaseating, granulomatous disorder of unknown cause that can affect any body system and is associated with cardiovascular disease including sudden cardiac death (SCD). Cardiac involvement in sarcoidosis is associated with higher risk of SCD, but the SCD risk in the general sarcoidosis population is unknown. We aimed to determine the risk of SCD in people with sarcoidosis versus the matched general population. Methods and Results A population-based cohort of sarcoidosis and age- and sex-matched comparators from January 1, 1976 to December 31, 2013 was used; presence of other comorbidities in the comparator group was not an exclusion criterion. Mortality, including time, place, and cause of death were measured and manually adjudicated for SCD events. Incidence rates are reported per 100 000 person-years, and Cox models were used for group comparisons. Of the 345 incident cases of sarcoidosis (171 men; 50%) there were 58 reported deaths; 10 were definite/probable SCD versus 57 all-cause and 9 SCDs in comparators. Median follow-up was 12.9 years (interquartile range, 6.0-23.4 years) . Incidence rate of SCD in sarcoidosis was 192 (95% CI, 92-352) versus 155 (95% CI, 71-294) in comparators (hazard ratio [HR], 1.28 (95% CI, 0.52-3.17). Nocturnal deaths were more frequent in sarcoidosis 57 (95% CI, 12-168) versus 17 (95% CI, 0.4-95) (HR, 3.76 [95% CI, 0.39-36.47]). No significant differences were detected between the groups by sex, age, calendar year of diagnosis, or disease duration. Conclusions In a population-based cohort of patients with sarcoidosis, the risk for SCD compared with matched comparators was not increased. There were more nocturnal deaths among patients with sarcoidosis, yet this was statistically insignificant.

The mechanisms of coronavirus disease-2019 (COVID-19)-related myocardial injury comprise both direct viral invasion and indirect (hypercoagulability and immune-mediated) cellular injuries. Some patients with COVID-19 cardiac involvement have poor clinical outcomes, with preliminary data suggesting long-term structural and functional changes. These include persistent myocardial fibrosis, edema, and intraventricular thrombi with embolic events, while functionally, the left ventricle is enlarged, with a reduced ejection fraction and new-onset arrhythmias reported in a number of patients. Myocarditis post-COVID-19 vaccination is rare but more common among young male patients. Larger studies, including prospective data from biobanks, will be useful in expanding these early findings and determining their validity., Competing Interests: Dr Nazarian has received grants from the National Institutes of Health, ImriCor, Biosense Webster, and ADAS; and is a consultant to CardioSolv and ImroCor. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2022 The Authors.)

Importance: Myocarditis has been reported with COVID-19 but is not clearly recognized as a possible adverse event following COVID-19 vaccination., Objective: To describe myocarditis presenting after COVID-19 vaccination within the Military Health System., Design, Setting, and Participants: This retrospective case series studied patients within the US Military Health System who experienced myocarditis after COVID-19 vaccination between January and April 2021. Patients who sought care for chest pain following COVID-19 vaccination and were subsequently diagnosed with clinical myocarditis were included., Exposure: Receipt of a messenger RNA (mRNA) COVID-19 vaccine between January 1 and April 30, 2021., Main Outcomes and Measures: Clinical diagnosis of myocarditis after COVID-19 vaccination in the absence of other identified causes., Results: A total of 23 male patients (22 currently serving in the military and 1 retiree; median [range] age, 25 [20-51] years) presented with acute onset of marked chest pain within 4 days after receipt of an mRNA COVID-19 vaccine. All military members were previously healthy with a high level of fitness. Seven received the BNT162b2-mRNA vaccine and 16 received the mRNA-1273 vaccine. A total of 20 patients had symptom onset following the second dose of an appropriately spaced 2-dose series. All patients had significantly elevated cardiac troponin levels. Among 8 patients who underwent cardiac magnetic resonance imaging within the acute phase of illness, all had findings consistent with the clinical diagnosis of myocarditis. Additional testing did not identify other etiologies for myocarditis, including acute COVID-19 and other infections, ischemic injury, or underlying autoimmune conditions. All patients received brief supportive care and were recovered or recovering at the time of this report. The military administered more than 2.8 million doses of mRNA COVID-19 vaccine in this period. While the observed number of myocarditis cases was small, the number was higher than expected among male military members after a second vaccine dose., Conclusions and Relevance: In this case series, myocarditis occurred in previously healthy military patients with similar clinical presentations following receipt of an mRNA COVID-19 vaccine. Further surveillance and evaluation of this adverse event following immunization is warranted. Potential for rare vaccine-related adverse events must be considered in the context of the well-established risk of morbidity, including cardiac injury, following COVID-19 infection.

Myocarditis remains a clinical challenge in pediatrics. Originally, it was recognized at autopsy before the application of endomyocardial biopsy, which led to a histopathology-based diagnosis such as in the Dallas criteria. Given the invasive and low-sensitivity nature of endomyocardial biopsy, its diagnostic focus shifted to a reliance on clinical suspicion. With the advances of cardiac magnetic resonance, an examination of the whole heart in vivo has gained acceptance in the pursuit of a diagnosis of myocarditis. The presentation may vary from minimal symptoms to heart failure, life-threatening arrhythmias, or cardiogenic shock. Outcomes span full resolution to chronic heart failure and the need for heart transplantation with inadequate clues to predict the disease trajectory. The American Heart Association commissioned this writing group to explore the current knowledge and management within the field of pediatric myocarditis. This statement highlights advances in our understanding of the immunopathogenesis, new and shifting dominant pathogeneses, modern laboratory testing, and use of mechanical circulatory support, with a special emphasis on innovations in cardiac magnetic resonance imaging. Despite these strides forward, we struggle without a universally accepted definition of myocarditis, which impedes progress in disease-targeted therapy.

Endomyocardial biopsy (EMB) is an invasive procedure, globally most often used for the monitoring of heart transplant (HTx) rejection. In addition, EMB can have an important complementary role to the clinical assessment in establishing the diagnosis of diverse cardiac disorders, including myocarditis, cardiomyopathies, drug-related cardiotoxicity, amyloidosis, other infiltrative and storage disorders, and cardiac tumours. Improvements in EMB equipment and the development of new techniques for the analysis of EMB samples have significantly improved diagnostic precision of EMB. The present document is the result of the Trilateral Cooperation Project between the Heart Failure Association of the European Society of Cardiology, the Heart Failure Society of America, and the Japanese Heart Failure Society. It represents an expert consensus aiming to provide a comprehensive, up-to-date perspective on EMB, with a focus on the following main issues: (i) an overview of the practical approach to EMB, (ii) an update on indications for EMB, (iii) a revised plan for HTx rejection surveillance, (iv) the impact of multimodality imaging on EMB, and (v) the current clinical practice in the worldwide use of EMB., (© 2021 Elsevier Inc. and Journal of Cardiac Failure. [Published by Elsevier Inc.] All rights reserved.)

Dilated cardiomyopathy (DCM) is characterized by dilatation of the left ventricle and impaired systolic function and is the second most common cause of heart failure after coronary heart disease. The etiology of DCM is diverse including genetic pathogenic variants, infection, inflammation, autoimmune diseases, exposure to chemicals/toxins as well as endocrine and neuromuscular causes. DCM is inherited in 20-50% of cases where more than 30 genes have been implicated in the development of DCM with pathogenic variants in TTN (Titin) most frequently associated with disease. Even though male sex is a risk factor for heart failure, few studies have examined sex differences in the pathogenesis of DCM. We searched the literature for studies examining idiopathic or familial/genetic DCM that reported data by sex in order to determine the sex ratio of disease. We found 31 studies that reported data by sex for non-genetic DCM with an average overall sex ratio of 2.5:1 male to female and 7 studies for familial/genetic DCM with an overall average sex ratio of 1.7:1 male to female. No manuscripts that we found had more females than males in their studies. We describe basic and clinical research findings that may explain the increase in DCM in males over females based on sex differences in basic physiology and the immune and fibrotic response to damage caused by mutations, infections, chemotherapy agents and autoimmune responses.

Background: The incidence of peripartum cardiomyopathy (PPCM) is known through referral center databases that may be affected by referral, misclassification, and other biases. We sought to determine the community-based incidence and natural history of PPCM using the Rochester Epidemiology Project., Methods and Results: Incident cases of PPCM occurring between January 1, 1970, and December 31, 2014, were identified in Olmsted County, Minnesota. A total of 15 PPCM cases were confirmed yielding an incidence of 20.3 cases per 100,000 live births in Olmsted County, Minnesota. Clinical information, disease characteristics, and outcomes were extracted from medical records in a 27-county region of the Rochester Epidemiology Project including Olmsted County and matched in a 1:2 ratio with pregnant women without PPCM. A total of 48 women were identified with PPCM in the expanded 27-county region. There was 1 death and no transplants over a median of 7.3 years of follow-up. Six of the 23 women with subsequent pregnancies developed recurrent PPCM, all of whom recovered. Migraine and anxiety were identified as novel possible risk factors for PPCM., Conclusions: The population-based incidence of PPCM was 20.3 cases per 100,000 live births in Olmsted County, Minnesota. Cardiovascular outcomes were generally excellent in this community cohort., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Myocarditis is an inflammatory disease of the heart that may occur because of infections, immune system activation, or exposure to drugs. The diagnosis of myocarditis has changed due to the introduction of cardiac magnetic resonance imaging. We present an expert consensus document aimed to summarize the common terminology related to myocarditis meanwhile highlighting some areas of controversies and uncertainties and the unmet clinical needs. In fact, controversies persist regarding mechanisms that determine the transition from the initial trigger to myocardial inflammation and from acute myocardial damage to chronic ventricular dysfunction. It is still uncertain which viruses (besides enteroviruses) cause direct tissue damage, act as triggers for immune-mediated damage, or both. Regarding terminology, myocarditis can be characterized according to etiology, phase, and severity of the disease, predominant symptoms, and pathological findings. Clinically, acute myocarditis (AM) implies a short time elapsed from the onset of symptoms and diagnosis (generally <1 month). In contrast, chronic inflammatory cardiomyopathy indicates myocardial inflammation with established dilated cardiomyopathy or hypokinetic nondilated phenotype, which in the advanced stages evolves into fibrosis without detectable inflammation. Suggested diagnostic and treatment recommendations for AM and chronic inflammatory cardiomyopathy are mainly based on expert opinion given the lack of well-designed contemporary clinical studies in the field. We will provide a shared and practical approach to patient diagnosis and management, underlying differences between the European and US scientific statements on this topic. We explain the role of histology that defines subtypes of myocarditis and its prognostic and therapeutic implications.

Human coronavirus-associated myocarditis is known, and a number of coronavirus disease 19 (COVID-19)-related myocarditis cases have been reported. The pathophysiology of COVID-19-related myocarditis is thought to be a combination of direct viral injury and cardiac damage due to the host's immune response. COVID-19 myocarditis diagnosis should be guided by insights from previous coronavirus and other myocarditis experience. The clinical findings include changes in electrocardiogram and cardiac biomarkers, and impaired cardiac function. When cardiac magnetic resonance imaging is not feasible, cardiac computed tomographic angiography with delayed myocardial imaging may serve to exclude significant coronary artery disease and identify myocardial inflammatory patterns. Because many COVID-19 patients have cardiovascular comorbidities, myocardial infarction should be considered. If the diagnosis remains uncertain, an endomyocardial biopsy may help identify active cardiac infection through viral genome amplification and possibly refine the treatment risks of systemic immunosuppression. Arrhythmias are not uncommon in COVID-19 patients, but the pathophysiology is still speculative. Nevertheless, clinicians should be vigilant to provide prompt monitoring and treatment. The long-term impact of COVID-19 myocarditis, including the majority of mild cases, remains unknown.

Coronavirus disease 2019 (COVID-19) is a rapidly expanding global pandemic caused by severe acute respiratory syndrome coronavirus 2, resulting in significant morbidity and mortality. A substantial minority of patients hospitalized develop an acute COVID-19 cardiovascular syndrome, which can manifest with a variety of clinical presentations but often presents as an acute cardiac injury with cardiomyopathy, ventricular arrhythmias, and hemodynamic instability in the absence of obstructive coronary artery disease. The cause of this injury is uncertain but is suspected to be related to myocarditis, microvascular injury, systemic cytokine-mediated injury, or stress-related cardiomyopathy. Although histologically unproven, severe acute respiratory syndrome coronavirus 2 has the potential to directly replicate within cardiomyocytes and pericytes, leading to viral myocarditis. Systemically elevated cytokines are also known to be cardiotoxic and have the potential to result in profound myocardial injury. Prior experience with severe acute respiratory syndrome coronavirus 1 has helped expedite the evaluation of several promising therapies, including antiviral agents, interleukin-6 inhibitors, and convalescent serum. Management of acute COVID-19 cardiovascular syndrome should involve a multidisciplinary team including intensive care specialists, infectious disease specialists, and cardiologists. Priorities for managing acute COVID-19 cardiovascular syndrome include balancing the goals of minimizing healthcare staff exposure for testing that will not change clinical management with early recognition of the syndrome at a time point at which intervention may be most effective. This article aims to review the best available data on acute COVID-19 cardiovascular syndrome epidemiology, pathogenesis, diagnosis, and treatment. From these data, we propose a surveillance, diagnostic, and management strategy that balances potential patient risks and healthcare staff exposure with improvement in meaningful clinical outcomes.

Background: Sarcoidosis is a systemic granulomatous disease that may affect the myocardium. This study evaluated the diagnostic and prognostic value of 2-dimensional speckle tracking echocardiography in cardiac sarcoidosis (CS)., Methods: Eighty-three patients with extracardiac, biopsy-proven sarcoidosis and definite/probable diagnosis of cardiac involvement diagnosed from January 2005 through December 2016 were included. Strain parameters in early stages of CS, in a subgroup of 23 CS patients with left ventricular ejection fraction (LVEF) within normal limits (LVEF> 52% for men: > 54% for women, mean value: 57.3% ± 3.8%) and no wall motion abnormalities was compared with 97 controls (1:4) without cardiac disease. LV and right ventricular (RV) global longitudinal (GLS), circumferential (GCS), and radial (GRS) strain and strain rate (SR) analyses were performed with TomTec software and correlated with cardiac outcomes (including heart failure and arrhythmias). This study was approved by the Mayo Clinic Institutional Review Board, and all patients gave informed written consent to participate., Results: Mean age of CS patients was 53.6 ± 10.8 years, and 34.9% were women. Mean LVEF was 43.2% ± 12.4%; LV GLS, - 12.4% ± 3.7%; LV GCS, - 17.1% ± 6.5%; LV GRS, 29.3% ± 12.8%; and RV wall GLS, 14.6% ± 6.3%. In the 23 patients with early stage CS with normal LVEF and RV systolic function, strain parameters were significantly reduced when compared with controls (respectively: LV GLS, - 15.9% ± 2.5% vs - 18.2% ± 2.7% [P = .001]; RV GLS, - 16.9% ± 4.5% vs - 24.1% ± 4.0% [P < .001]). A LV GLS value of - 16.3% provided 82.2% sensitivity and 81.2% specificity for the diagnosis of CS (AUC 0.91), while a RV value of - 19.9% provided 88.1% sensitivity and 86.7% specificity (AUC 0.93). Hospital admission and heart failure significantly correlated to impaired LV GLS (> - 14%)., Conclusion: Reduced strain values in the LV GLS and RV GLS can be used in the diagnostic algorithm in patients with suspicion of cardiac sarcoidosis. These values also correlate with adverse cardiovascular events.

Objective: To examine the association between maternal obesity on left ventricular (LV) size and recovery in women with peripartum cardiomyopathy (PPCM)., Study Design: This was a prospective analysis of 100 women enrolled within 13 weeks of PPCM diagnosis and followed for a year in the Investigation of Pregnancy Associated Cardiomyopathy study. Adiposity was defined by standard body mass index (BMI) definitions for under/normal weight, overweight, and obesity. Demographic, clinical, and biomarker variables were compared across weight categories., Outcomes: LV end-diastolic diameter (LVEDD) and ejection fraction were measured at entry, 6, and 12 months postpartum. Multivariable regression models examined the relationship between adiposity, LV size, and leptin levels with cardiac recovery at 6 and 12 months postpartum., Results: Obese and nonobese women had similar LV dysfunction at entry. Obese women had greater LV size and less LV recovery at 6 and 12 months postpartum. BMI was positively associated with leptin and ventricular diameter. Greater BMI at entry remained associated with less ventricular recovery at 6 months ( p  = 0.02) in adjusted race-stratified models. LVEDD at entry predicted lower ejection fraction at 6 months ( p  < 0.001) and similarly at 12 months., Conclusion: Obese women with PPCM had greater cardiac remodeling, higher leptin levels, and diminished cardiac recovery., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background Myocarditis is an important cause of acute and chronic heart failure. Men with myocarditis have worse recovery and an increased need for transplantation compared with women, but the reason for the sex difference remains unclear. Elevated sera soluble (s) ST2 predicts mortality from acute and chronic heart failure, but has not been studied in myocarditis patients. Methods and Results Adults with a diagnosis of clinically suspected myocarditis (n=303, 78% male) were identified according to the 2013 European Society of Cardiology position statement. Sera sST2 levels were examined by ELISA in humans and mice and correlated with heart function according to sex and age. Sera sST2 levels were higher in healthy men ( P=8×10 -6 ) and men with myocarditis ( P=0.004) compared with women. sST2 levels were elevated in patients with myocarditis and New York Heart Association class III - IV heart failure ( P=0.002), predominantly in men ( P=0.0003). Sera sST2 levels were associated with New York Heart Association class in men with myocarditis who were ≤50 years old ( r=0.231, P=0.0006), but not in women ( r=0.172, P=0.57). Sera sST2 levels were also significantly higher in male mice with myocarditis ( P=0.005) where levels were associated with cardiac inflammation. Gonadectomy with hormone replacement showed that testosterone ( P<0.001), but not estradiol ( P=0.32), increased sera sST2 levels in male mice with myocarditis. Conclusions We show in a well-characterized subset of heart failure patients with clinically suspected and biopsy-confirmed myocarditis that elevated sera sST2 is associated with an increased risk of heart failure based on New York Heart Association class in men ≤50 years old.