Update on acute myocarditis

Abstract

Acute myocarditis (AM), a recent-onset inflammation of the heart, has heterogeneous clinical presentations, varying from minor symptoms to high-risk cardiac conditions with severe heart failure, refractory arrhythmias, and cardiogenic shock. AM is moving from being a definitive diagnosis based on histological evidence of inflammatory infiltrates on cardiac tissue to a working diagnosis supported by high sensitivity troponin increase in association with specific cardiac magnetic resonance imaging (CMRI) findings. Though experts still diverge between those advocating for histological definition versus those supporting a mainly clinical definition of myocarditis, in the real-world practice the diagnosis of AM has undoubtedly shifted from being mainly biopsy-based to solely CMRI-based in most of clinical scenarios. It is thus important to clearly define selected settings where EMB is a must, as information derived from histology is essential for an optimal management. As in other medical conditions, a risk-based approach should be promoted in order to identify the most severe AM cases requiring appropriate bundles of care, including early recognition, transfer to tertiary centers, aggressive circulatory supports with inotropes and mechanical devices, histologic confirmation and eventual immunosuppressive therapy. Despite improvements in recognition and treatment of AM, including a broader use of promising mechanical circulatory supports, severe forms of AM are still burdened by dismal outcomes. This review is focused on recent clinical studies and registries that shed new insights on AM. Attention will be paid to contemporary outcomes and predictors of prognosis, the emerging entity of immune checkpoint inhibitors-associated myocarditis, updated CMRI diagnostic criteria, new data on the use of temporary mechanical circulatory supports in fulminant myocarditis. The role of viruses as etiologic agents will be reviewed and a brief update on pediatric AM is also provided. Finally, we summarize a risk-based approach to AM, based on available evidence and clinical experience.

Fulminant myocarditis: a comprehensive review from etiology to treatments and outcomes

“…146 Our therapeutic approach is supported by Ammirati's work by placing an emphasis on the importance of both MCS and immunomodulation therapy. 45,147 We propose this is the key to a successful treatment of FM. However, there are some differences between the two regimens.…”

Pre-Existing Cardiovascular Conditions as Clinical Predictors of Myocarditis Reporting with Immune Checkpoint Inhibitors: A VigiBase Study

“…ICI-related myocarditis differs from classical acute myocarditis (which is generally caused by a post-viral immune response) in terms of both clinical presentations and outcomes [ 3 , 4 ]. Patients with ICI-related myocarditis are typically older than patients with non-ICI-related forms of myocarditis (64 years versus 34 years), have other chronic comorbidities in addition to their cancer, and show a higher mortality rate [ 5 ]. Identification of clinical risk factors predicting ICI-related myocarditis therefore is of primary importance, especially in view of increased ICI prescription [ 6 ].…”

Immunomodulatory Role of Tenascin-C in Myocarditis and Inflammatory Cardiomyopathy

“…Infection with the novel pathogen severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger myocarditis both directly and indirectly ( 14 , 21 ). Several studies have suggested that the immune response triggered by the virus is the major cause of cardiomyocyte injury, rather than direct virus-mediated cytotoxicity ( 15 , 22 ). In a recent series of hospitalized coronavirus disease 2019 (COVID-19) cases caused by SARS-CoV-2 infection, acute cardiac injury with serum troponin elevation occurred in 7% to 27% of patients, and elevated troponin levels were associated with increased mortality in patients with COVID-19 ( 23 – 25 ).…”