Fulminant myocarditis due to influenza B virus in adults: Report of two cases and review of the literature

Myocarditis is an inflammatory disease of the myocardium. Viral infections are the most common cause, although it can also be due to hypersensitivity reactions and autoimmune etiology, among other causes. The clinical spectrum of the disease is varied, from an asymptomatic course, followed by chest pain, arrhythmias and acute heart failure, to fulminant picture. The term fulminant refers to the development of cardiogenic shock with the need for vasopressor support, inotropic or assisted circulation devices either extracorporeal membrane oxygenation (ECMO) or intra-aortic counterpulsation balloon. About 10% of cases of heart failure due to myocarditis correspond to fulminant myocarditis. Influenza myocarditis has been considered an infrequent condition, however, its incidence has increased since 2009 as a result of the AH1N1 pandemic; otherwise, myocarditis due to Influenza type B remains an infrequent entity. We describe the experience in a cardiovascular center of 2 confirmed cases of fulminant myocarditis due to Influenza B that required circulatory assistance devices.