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Flu Vaccines May Protect the Heart Too

Flu Vaccine and Heart Risks continued...

The CDC advises all adults, including adults with underlying conditions like diabetes and heart disease, to get an annual flu vaccine. Still, most don’t. According to the CDC, only about 40% of adults were vaccinated against the flu during the last flu season.

For the second study, researchers surveyed 230 patients at the same hospital who all had implanted cardiac defibrillators (ICDs), devices that shock the heart when it goes into dangerous, irregular rhythms.

Patients with ICDs tend to get more jolts from those devices during the winter months, and doctors wondered whether that might have something to do with the flu.

About 80% of the ICD patients said they’d gotten a flu vaccine that season, and about 20% did not. Researchers say the patients who got flu vaccines had fewer ICD shocks to the heart than patients who didn’t get flu vaccines. They couldn’t rule out that the differences between the two groups might have been due to chance alone, however.

“Our finding is thought-provoking,” says researcher Sheldon Singh, MD, assistant professor of medicine at the University of Toronto, in Canada. “If this finding is reproducible, if this is a real finding, flu shots may have real benefits for our patients.”

How the Flu May Harm the Heart

How might flu vaccines be helping the heart?

Udell says there are two theories: that the vaccines may protect vulnerable patients or that they protect unstable buildups in artery walls from breaking open and cutting off blood flow to the heart or brain.

“The vulnerable patient theory goes, if you have heart disease or diabetes or some other major risk factor and then you get the flu, you get congested and can’t breathe as well and it lowers the oxygen that’s going to vital organ tissues like the brain and heart, and that can lead to heart attacks and strokes,” Udell says.

The vulnerable buildup theory suggests that inflammation caused by a viral infection triggers the rupture of artery-clogging plaques.

“This is one instance where there’s a clear benefit,” says Len Horovitz, MD, a pulmonary and internal medicine specialist at Lenox Hill Hospital in New York City.

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