Diagnostic trends in patients hospitalized with suspected myocarditis: 10-year data from the nationwide MYO-PL database.

Background: Myocarditis poses a great diagnostic challenge to clinicians, as the most sensitive diagnostic tools are not easily accessible in many hospitals. Clinical suspicion of myocarditis is based on clinical symptoms and additional tests' abnormalities. The diagnosis should be confirmed by endomyocardial biopsy (EMB) - the gold standard for the diagnosis of myocarditis. The study aimed to assess trends in the use of diagnostic procedures performed in all patients hospitalized with suspected myocarditis in Poland between 2011-2019.

Methods: The nationwide MYO-PL database was derived from the database of the national healthcare insurer and created to identify hospitalization records with a primary diagnosis of myocarditis. We evaluated the use of recommended diagnostic procedures in this group of 19 978 patients within 6 months of the diagnosis of myocarditis.

Results: Echocardiography was the most frequently used imaging technique among patients, and the number of patients who underwent this procedure between 2011-2019 rose every year (71.3-86.1%). Use of nuclear medicine procedures remained < 1% regardless of the year. Biomarkers measurements during primary hospitalization were performed in 13.8% (brain natriuretic peptides) and 41.3% (troponins) of patients. Interestingly, EMB was performed in less than 1% of patients. The most sensitive noninvasive test (cardiac magnetic resonance) was performed in 16.4% of patients (7.2-29.2% within 10 years). Most diagnostic tests were less frequently performed in females.

Conclusions: The results highlight that the management of patients with myocarditis could be significantly improved if state-of-the-art diagnostic methods were followed according to guidelines.