QRS fragmentation in children with suspected myocarditis: a possible additional diagnostic sign

We aim to assess the diagnostic role of QRS fragmentation in children with suspected acute myocarditis.

Diagnosis of myocarditis in the paediatric population is challenging. Clinical suspicion, electrocardiogram, and laboratory tests are the main diagnostic features at presentation. However, electrocardiogram in patients with myocarditis is usually considered aspecific. We have previously described QRS fragmentation in adult patients with acute myocarditis.

Patients aged less than 18 years, admitted between 2003 and 2019, and discharged with a diagnosis of acute myocarditis were included. Standard electrocardiogram, laboratory, and echocardiographic findings at admission and follow-up were reviewed. QRS fragmentation was defined by the presence of multiphasic R' spikes. Cardiac magnetic resonance and biopsy were performed in selected patients.

Twenty-one patients were analysed, 16 males (76%), median age 9.5 (2.5-16) years. At presentation, 12 patients (57%) displayed QRS fragmentation. Median ejection fraction was 40% (27-60). Nine patients (43%) underwent cardiac magnetic resonance and displayed late gadolinium enhancement. One patient underwent biopsy that showed borderline findings. Electrocardiogram leads showing QRS fragmentation correlated with distribution of late gadolinium enhancement. Median follow-up was 600 (190-2343) days. All patients were alive at last follow-up. Six patients (33%) patients displayed persistence of QRS fragmentation. Median ejection fraction was 60% (60-65%). In three patients (14%), ejection fraction remained depressed, two of which showed persistence of QRS fragmentation.

In this cohort of children with suspected myocarditis, QRS fragmentation was confirmed as a new additional diagnostic finding to look for at admission and during follow-up.