Heart Attack Risk Spikes After Flu


The risk of suffering a heart attack rises sharply in the days following a flu infection, a study in The New England Journal of Medicine confirms.

Experts have long believed that a bout of the flu can trigger a heart attack in vulnerable people. But this study bolsters the evidence and suggests the usual low odds of a heart attack are, on average, six times higher than normal in the week or so following a flu infection.

The findings, which were published last year, are based on 332 patients who were hospitalized for a heart attack in the year before or after suffering a definite flu infection (confirmed by lab testing). Twenty of those hospitalizations happened in the week after patients were tested for the flu. The rest happened in the year before or after—at a rate of 3.3 hospitalizations per week. That translated into a sixfold greater risk of heart attack in the week after testing positive for flu. Beyond day seven, though, there was no longer a heightened risk.

Why would the flu trigger a heart attack? The infection causes inflammation, which could potentially disrupt an existing plaque in an artery. Infections can also hinder normal artery functioning and make the blood more prone to clotting.

The findings underscore some long-standing advice: Get a flu shot every year. Beyond that, you can protect yourself through frequent hand-washing and staying away from people who are sick.