COVID-19-associated multisystem inflammatory syndrome in children presenting uniquely with sinus node dysfunction in the setting of shock.

SARS-CoV-2, which causes the disease COVID-19, generally has a mild disease course in children. However, a severe post-infectious inflammatory process known as multisystem inflammatory syndrome in children has been observed in association with COVID-19. This inflammatory process is a result of an abnormal immune response with similar clinical features to Kawasaki disease. It is well established that multisystem inflammatory syndrome in children is associated with myocardial dysfunction, coronary artery dilation or aneurysms, and occasionally arrhythmias. The most common electrocardiographic abnormalities seen include premature atrial or ventricular ectopy, variable degrees of atrioventricular block, and QTc prolongation, and rarely, haemodynamically significant arrhythmias necessitating extracorporeal membrane oxygenation support. However, presentation with fever, hypotension, and relative bradycardia with a left axis idioventricular rhythm has not been previously reported. We present a case of a young adolescent with multisystem inflammatory syndrome in children with myocarditis and a profoundly inappropriate sinus node response to shock with complete resolution following intravenous immunoglobulin.