Clinical course, viral etiology, and the diagnostic workup for patients with suspected myocarditis: a single-center prospective study.

Background: Myocarditis is a highly heterogeneous disorder with a challenging diagnostic work-up. We aimed to focus on the possible diagnostic workup for this condition in settings where endomyocardial biopsy as a gold standard is not always feasible, detect the etiologic cardiotropic viruses in our locality, and follow the clinical course in patients admitted with clinically suspected myocarditis.

Methods: This is a prospective observational study. We recruited patients with clinically suspected myocarditis presenting at a university hospital from October 1st, 2020 until March 31st, 2021. All Patients had a diagnostic coronary angiography and were included only if they had a non-obstructive coronary artery disease. All patients also had cardiac magnetic resonance imaging (CMR) with contrast. Sera were obtained from all suspected patients for detection of antibodies against viruses using enzyme-linked immunosorbent assay, and viral genomes using polymerase chain reaction (PCR), and reverse transcription-PCR. Endomyocardial biopsy was done for patients with a typical CMR picture of myocarditis.

Results: Out of 2163 patients presenting to the hospital within the 6 months, only 51 met the inclusion criteria. Males represented 73%, with a mean age of 39 ± 16 years. CMR showed an ischemic pattern in 4 patients and thus they were excluded. We classified patients into two categories based on CMR results: group A (CMR-positive myocarditis), 12 patients (25.5%), and group B (CMR-negative myocarditis), 35 (74.5%) patients. On serological analysis, 66% of patients (n = 31/47) showed antibodies against the common cardiotropic viruses. Parvovirus B19 IgM in 22 patients (47%) and coxsackievirus IgM in 16 (34%) were the most observed etiologies. Regarding the outcome, 42.5% of patients recovered left ventricular ejection fraction and three patients died at 6 months' clinical follow-up.

Conclusion: Patients with Clinically suspected myocarditis represented 2.2% of total hospital admissions in 6 months. CMR is only a good positive test for the diagnosis of acute myocarditis. Parvovirus B19 and coxsackievirus were the most common pathogens in our locality.

Trial Registration: Clinical trial registration no., NCT04312490; first registration: 18/03/2020. First recruited case 01/10/2020. URL: https://register.

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