LONDON, Sept. 22 (UPI) -- Influenza, both seasonal and H1N1, may trigger a heart attack and cardiovascular death in cardiac patients, a British review found.
Charlotte Warren-Gash of University College London and colleagues said it is well known that influenza is associated with cardiac complications but it remains unclear what role the virus plays in triggering a heart attack.
However, it is believed that flu might cause heart attack through inflammatory effects that destabilize atherosclerotic plaque, causing blockages resulting in heart attacks, Warren-Gash said in a statement.
The researchers performed a systematic review of 42 papers describing 39 studies conducted from 1932-2008.
The review, published in The Lancet Infectious Diseases, said all observational studies included in the review found an association between times when influenza viruses were circulating and increases in cardiovascular death.
"We believe influenza vaccination should be encouraged wherever indicated, especially in those people with existing cardiovascular disease, among whom there is often suboptimum vaccine uptake," Warren-Gash said in a statement.
