This year’s flu season is already one of the worst on record.
Now there’s evidence that getting sick with the flu increases your chances of having a heart attack by sixfold within a week of onset — even more if you’re an older adult.
In a study published today in the New England Journal of Medicine (NEJM), researchers at the Institute for Clinical Evaluative Sciences and Public Health Ontario say they found a direct correlation between acute respiratory infections — particularly influenza — and acute myocardial infarctions, more commonly known as heart attacks.
Other respiratory infections also elevate the risk of heart attack, the researchers found, although not as much as the flu.
The report confirmed the relationship between the flu and heart problems that medical specialists have been aware of for years.
“This flu season, we’ve seen a significant increase of cardiac ICU patients who are having heart attacks or other heart complications such as heart failure,” Dr. Janet Wei, FACC, a cardiologist in the Barbra Streisand Women’s Heart Center in the Cedars-Sinai Heart Institute in Los Angeles, told Healthline.
“Strokes are also three times as likely to occur following the onset of a flu infection,” Wei said, citing a prior NEJM article.
Why the flu causes heart attacks
According to heart doctors, the stress to the body from the flu creates conditions that can bring on a heart attack.
“We appreciate that myocardial infarction is often the result of a systemic process, such as systemic inflammation or a predilection to blood clots,” Dr. Michael Blaha, MPH, director of clinical research at the Ciccarone Center for the Prevention of Heart Disease at Johns Hopkins Medicine in Maryland, told Healthline.
“We know a variety of things — natural disasters, emotional reactions, depression, financial stress, when your soccer team loses… any situation where there is stress — that cause the sympathetic nervous system to ramp up also causes blood pressure to rise. This activation puts you at risk,” Blaha added.
The study identified people experiencing a first-time heart attack as particularly at-risk following a flu infection.
“We identify risk factors, family history, genetic origin, early plaque in arteries,” Blaha said. “But even if someone is high risk, we expect that risk of a heart attack for the next 10 years — not within a week or month. There are acute triggers — such as infection, someone who is predisposed — but [they] may not have had that heart attack if they had been infection-free. Preventing infections as well as stress management and sleep are important for heart health.”
Reducing the risk
The findings reinforce the importance of vaccination, as well as the need for people at risk of heart disease to take precautions against respiratory infections.
These precautions include practices such as handwashing.
“All adults should get a flu vaccine, especially people who are susceptible to getting sick,” Blaha said. “It goes beyond preventing flu. It could reduce the chances of a lot of pertinent disease — and heart attacks.”
A earlier article in the NEJM showed that the flu vaccine was linked to fewer hospitalizations — and 50 percent fewer deaths.
“Patients who get the flu but who got the vaccine versus those who didn’t are less likely to be hospitalized in the ICU,” Wei said. “They experience less severe complications from the flu.”
“Some people refuse the flu vaccine because they heard it isn’t effective,” she added, “but we have evidence that shows you should still get it for its benefits, to lessen the severity of the infection, and reduce the likelihood of heart attacks, heart failures, and strokes.”
The researchers added that anyone experiencing heart symptoms shouldn’t delay medical evaluation, especially if they occur within the first week of the flu.