We have seen some of the cases in our threads here at allnurses.
Quote from crofsblogs.typepad.com
The prevalence of myocardial involvement in influenza infection ranges from 0 to 11% depending on the diagnostic criteria used to define myocarditis (4).
Fulminant myocarditis is an uncommon complication, typically diagnosed in association with circulatory collapse or at autopsy in patients with influenza-associated fatal outcomes (5). A few case reports and series (6-8) represent the incidental diagnoses of influenza-associated acute fulminant myocarditis, but the true prevalence remains unknown.
Here we present the first known report of acute myocarditis in pediatric population associated with the present pandemic H1N1 influenza A virus infection. Four cases occurred within a 30-day period, and 3 of them were diagnosed as fulminant myocarditis with fatal or near-fatal outcomes.