Coronary Artery Dilatation in Viral Myocarditis Mimics Coronary Artery Findings in Kawasaki Disease.

Coronary artery (CA) dilatations are typical to Kawasaki disease (KD) in the pediatric population. CA involvement is a useful feature to help establish the diagnosis of KD. Since myocarditis is omnipresent in the acute phase of KD, we sought to investigate whether viral myocarditis may cause CA dilatation. This retrospective study reviewed 14 consecutive patients diagnosed with acute myocarditis at CHU Sainte-Justine, Montreal. KD diagnosis was excluded for all patients. All echocardiography studies were reviewed by an independent experienced echocardiographer for CA size and myocardial function parameters. CA involvement was classified under three categories: definite dilatation (Z-score ≥2.5 in one or more CA), occult dilatation (Z-score variation ≥2 points for the same CA on two different echocardiograms, but maximum Z-score always <2.5), and no dilatation otherwise. Demographics, laboratory values, microbial etiology testing, and diagnostic studies were collected from medical records. Mean age at presentation was 1.67 ± 3.22 years, where 11/14 (78 %) presented with acute and three with subacute myocarditis. Five (36 %) patients had normal CA measurements, six (43 %) had occult dilatation, and three (21 %) had definite dilatation. Maximal CA Z-score was within the first 8 days of presentation. Patients with viral myocarditis can present CA dilatation during the acute phase of the illness. This finding should be taken into account when KD diagnosis is being based on the CA involvement as the two illnesses may present with similar features.