Hemodynamic Collapse After Influenza Vaccination: A Vaccine-Induced Fulminant Myocarditis?

A 14-year-old girl with cardiopulmonary arrest was referred to our hospital. She had received an injection of inactivated influenza vaccine 7 days before the referral. Her cardiac rhythm was pulseless wide QRS tachycardia, and mechanical circulatory support was immediately begun. Results of endomyocardial biopsy showed that there was massive infiltration of CD3- and CD68-positive cells and various degrees of cardiomyocyte necrosis in all of 3 endomyocardial specimens, whereas infiltration of eosinophils or giant cells was not observed. A histologic diagnosis of lymphocytic myocarditis was made. Acute myocarditis is a rare but potentially fatal complication of the influenza vaccination.