Akira Ukimura, Kanta Kishi, Tomoyuki Yamada, Yuriko Shibata, Yukimasa Ooi, Yumiko Kanzaki and Hiroshi Tamai
An Influenza pandemic occurred in 2009. A nationwide, retrospective survey of Influenza myocarditis in Japanese children in 3 consecutive Influenza seasons was performed to compare Influenza myocarditis in the 2009/2010 season (the pandemic season), the 2010/2011 season, and the 2011/2012 season, by mailing questionnaires to 514 hospitals in Japan that have pediatric departments and collecting data from 285 hospitals. A questionnaire-based survey related to Influenza myocarditis was also conducted to evaluate the attitudes of Japanese pediatricians concerning the diagnosis of Influenza myocarditis. Fifteen Influenza myocarditis patients were reported, with 8 (H1N1pdm:6, type A:1, type B:1) from the 2009/10 season, 4 (type A:1, type B:3) from the 2010/11 season, and 3 (type B:3) from the 2011/12 season. Only 8 patients with Influenza A virus myocarditis were reported, with 7 patients from the 2009/2010 season, one from the 2010/2011 season, and none in the 2011/2012 season. Mortality was 33.3% (5/15) among the myocarditis patients. Twelve patients (12/15, 80%) were diagnosed with fulminant myocarditis with fatal arrhythmias and/or cardiogenic shock. In the pediatricians’ attitude survey, only 3.3% of pediatricians routinely examined the electrocardiograms of children hospitalized with Influenza infection in Japan. The number of Japanese children with myocarditis associated with Influenza A virus seemed to increase in the pandemic season. Increased awareness of Influenza myocarditis in children is needed during future Influenza pandemics.