Myocarditis Associated with Influenza A H1N1pdm2009

Area of Science:

• Cardiology
• Infectious Diseases
• Virology

Background:

• Acute myocarditis is a known complication of influenza infections.
• Myocardial involvement in influenza ranges from asymptomatic to severe, potentially fatal forms.
• Fulminant myocarditis due to influenza is considered rare.

Purpose of the Study:

• To investigate the clinical features and prevalence of myocarditis associated with the 2009 H1N1 influenza pandemic.
• To highlight the frequency of fulminant myocarditis in H1N1pdm2009 infections.

Main Methods:

• Analysis of a cohort of 15 patients in Japan with H1N1pdm2009 myocarditis.
• Literature review of case reports and series of H1N1pdm2009-associated myocarditis, identifying 58 detailed cases.

Main Results:

• A high prevalence of fulminant myocarditis (62%, 36/58 cases) was observed among reported H1N1pdm2009-associated myocarditis cases.
• Mechanical circulatory support was necessary for 17 patients with fulminant myocarditis, with 13 achieving recovery.
• The study identified a significant proportion of severe cardiac complications.

Conclusions:

• Influenza-associated myocarditis, particularly the fulminant form, may be more prevalent than previously thought.
• Increased awareness is crucial for earlier diagnosis and treatment of this potentially fatal complication during influenza pandemics.
• Prompt medical intervention, including mechanical support, can lead to recovery in severe cases.