%0 Journal Article
%T Myocarditis Associated with Influenza A H1N1pdm2009
%A Akira Ukimura
%A Hidetoshi Satomi
%A Yukimasa Ooi
%A Yumiko Kanzaki
%J Influenza Research and Treatment
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/351979
%X Acute myocarditis is a well-known complication of influenza infection. The frequency of myocardial involvement in influenza infection varies widely, with the clinical severity ranging from asymptomatic to fulminant varieties. The worst cases can result in death due to impaired cardiac function, although such fulminant myocarditis associated with influenza infection is rare, as shown by previous papers. Following the 2009 influenza pandemic, we reported on the clinical features of a cohort of 15 patients in Japan with H1N1pdm2009 myocarditis. In our subsequent survey of the literature for case reports or series of patients with myocarditis associated with H1N1pdm2009, we identified 58 detailed cases. We discuss here the high prevalence of fulminant myocarditis (36/58, 62%) among patients reported to have myocarditis associated with H1N1pdm2009. Mechanical circulatory support was required in 17 of the patients with fulminant myocarditis, 13 of whom recovered. We stress the need for increased awareness of influenza-associated myocarditis; such knowledge will facilitate earlier diagnosis and treatment of this fatal complication during future influenza pandemics. 1. Introduction Acute myocarditis is a well-known complication of influenza infection. The clinical expression varies from asymptomatic to fulminant myocarditis, which can result in severe hemodynamic dysfunction, necessitating high-dose catecholamines and mechanical circulatory support [1每11]. Pathogens frequently associated with myocarditis include coxsackievirus and adenovirus; fulminant myocarditis resulting from influenza A viral infection is rare, as shown by previous literature [1每23]. Our interest in influenza-associated myocarditis follows from our experience with the influenza pandemic of 2009 [3, 24每30]. We surveyed the literature for case reports and series involving myocarditis associated with H1N1pdm2009, and identified 58 patients with such a diagnosis [3, 31每62]. In the present study, we review the clinical, laboratory, and pathologic characteristics of these 58 patients and theorize about the pathogenesis of influenza myocarditis [63每68]. 2. Cardiac Involvement of Influenza Infectionˋˋbefore the 2009 Pandemic Myocarditis was a common and sometimes fatal complication of influenza infection in the pandemics of the previous century [1每7]. Small autopsy-based studies on fatal cases revealed a complication rate of focal to diffuse myocarditis of 39.4% during the 1957 Asian influenza pandemic and 48% during the Spanish influenza pandemic [4每6]. All of these fatal cases with myocarditis
%U http://www.hindawi.com/journals/irt/2012/351979/