Myocarditis and Kawasaki disease.

Kawasaki disease (KD) is the most common vasculitis of childhood. Coronary artery aneurysms and myocarditis are common cardiovascular complications of KD. While evidence of myocarditis can be found in all patients with KD on histology specimens, only a minority of patients are clinically symptomatic. Occasionally children can present with KD shock syndrome and hemodynamic instability as a result of decreased systolic function and vasoplegia. Several children with KD have depressed shortening fraction on echocardiography. Increased end-systolic and end-diastolic dimensions, strain abnormalities and diastolic dysfunction are also found in a significant proportion of patients. Echocardiographic signs of myocarditis improve after the acute phase and do so more quickly in patients who have received intravenous immunoglobulins, as opposed to those given only aspirin. Normalization of systolic function is typically observed over long-term follow-up; however, more subtle abnormalities (strain, diastolic function) may persist. It is noteworthy that myocarditis associated with KD can occur in absence of coronary artery abnormalities. KD myocarditis can result in long-term sequelae.