Research reveals flu can increase heart attack risk six times in a week

A new study has shown that catching the influenza virus can increase the risk of having a heart attack by up to six times within the space of only a week.

The study, published in the New England Journal of Medicine, looked at thousands of flu cased and provided strong evidence linking influenza and heart attacks.

The study, Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection, looked at nearly 20,000 cases of laboratory-confirmed flu infection from 2009 to 2014.

Of these patients, 332 were hospitalised for a heart attack within one year of a laboratory-confirmed influenza diagnosis. The results showed that for seven days after flu was detected, there was a six-fold increase in the chances of patients suffering heart attacks.

“We identified 364 hospitalisations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza,” the report stated. “We found a significant association between respiratory infections, especially influenza, and acute myocardial infarction.”

According to the study, the heart attack rate was 20 admissions per week seven days after a flu diagnosis, compared to only 3.3 heart attack admissions a week in the year before and after a flu diagnosis.

The risk was identified as higher for older adults, patients with influenza B infections, and those experiencing their first heart attack, said the researchers. In particular, the researchers found that the risk of heart attack increases slightly for those over 65.

Meanwhile a less extreme raised risk of heart attack was also associated with other respiratory viral infections besides influenza. Sixty nine percent of the 332 people in the study who had a heart attack following a flu diagnosis had not gotten a flu shot, according to the study.

According to the report, previous studies have suggested an association between influenza and acute myocardial infarction, but those studies had used non-specific measures of influenza infection or study designs that were susceptible to bias. But in this study, researchers concluded they have now found a significant association between respiratory infections, especially influenza, and acute myocardial infarction.