ABC Heart Fail Cardiomyop 2023; 3(1): e20230037

Viewpoint – Brazilian Guideline for Myocarditis

Marcelo Westerlund Montera, Daniella Motta da Costa Dan , Fabiana G. Marcondes-Braga

DOI: 10.36660/abchf.20230037

Diagnosis

The criterion for the diagnostic confirmation of myocarditis defined by the 2013 European and Brazilian Myocarditis Guidelines is the identification of myocardial inflammation by endomyocardial biopsy (EMB).^, This diagnostic criterion, used solely without the option of classifying clinical suspicion, does not mirror clinical practice in the real world, where only a minority of patients in specialized centers are referred for diagnostic investigation through EMB with diagnostic confirmation or exclusion, and most have the diagnosis of clinical suspicion of myocarditis. As an innovation, the 2022 Brazilian Guideline introduces an organizational chart to establish the degrees of suspected diagnosis of myocarditis, which correspond to clinical practice in the real world, where most patients will have a diagnosis of suspected myocarditis rather than confirmation. This organization chart is based on clinical history, myocardial injury biomarkers, electrocardiogram, echocardiogram, and cardiac magnetic resonance, to establish a diagnostic suspicion of myocarditis (), which will define different approaches regarding follow-up, treatment, and the need for EMB. Patients with low suspicion of myocarditis have a favorable prognosis with a low risk of developing ventricular dysfunction or cardiovascular mortality, and clinical follow-up is indicated without the need for cardioprotective drugs. Cardioprotective drugs and clinical and ventricular function follow-up by echocardiogram and magnetic resonance imaging are indicated for patients with an intermediate degree of suspicion of miocarditis. Patients with high diagnostic suspicion or with intermediate suspicion with worsening clinical or ventricular function have a worse long-term prognosis, with lower survival, being indicated in this group the EMB for the investigation of the inflammatory activity and the etiological agent to evaluate treatment with immunosuppressants and therapy directed towards the identified etiological factor (). With the diagnostic suspicion classification, the new Guideline approaches clinical practice, standardizing the clinical management of most patients with suspected myocarditis and reserving the indication of EMB for those with greater potential for clinical benefit from immunosuppressive therapy.

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