People are six times more likely to have a heart attack in the week after a flu than in the entire year before or after the flu, a new study has found.
The study, cited by Study Findsanalyzed data from more than 26,000 patients in the Netherlands to see the increased risk of attacks when you have the flu.
It has long been known that the flu virus increases the “stickiness” of the blood which, along with inflammation, can weaken fatty plaques in the arteries and cause a clot.
A research team at the University Medical Center (UMC) Utrecht, responsible for the study, hopes that their research will help underline the importance of vaccination and raise awareness of heart attack symptoms among flu patients.
While the link between heart attacks and the flu is not a breakthrough, previous studies have only focused on individuals hospitalized for a heart attack. A 2018 Canadian study did not include death records, meaning the scientists did not take into account those that occurred outside of hospitals.
In this study, however, the UMC Utrecht team used test results from 16 laboratories in the Netherlands, covering about two-fifths of the population, along with the death and hospital recordsto get a more accurate and complete view.
Across all Dutch laboratories, the team recorded 26,221 cases of flu between 2008 and 2019. Just over 400 of those with flu had at least one heart attack within a year of their flu diagnosis. Of the 419 patients who had heart attacks, 25 occurred within the first seven days of being diagnosed with the flu.
Another 217 had heart attacks in the year before their diagnosis and 177 had theirs in the year after their diagnosis, after the first week. About a third of individuals died the following year to the diagnosis of flu.
Annemarijn de Boer and the research team calculated that those individuals analyzed were 6.16 times more likely to have a heart attack in the first seven days after their flu diagnosis than in the entire year before and after diagnosis.
A 2018 Canadian study had that number at about 6.05 times. However, excluding death records, the increased risk of heart attacks in the week following the diagnosis was reduced to 2.42 times.
The Dutch researchers feel that this illustrates the impact that incomplete data can have on study outcomes. They add that differences in testing practices in the two countries may explain why they found the association between flu and heart attacks weaker than in the Canadian study.
Testing people for the flu outside of hospitals is less common in the Netherlands than in Canada. However, the association is still significant and, using a method similar to that of the Canadian scientists, the UMC Utrecht team was able to confirm the increased risk in different populations.
Along with the blood clotting that the flu can cause, it is believed that the inflammation also weakens the fatty plaques that build up in the arteries. If one of these plaques ruptures, a blood clot can form, blocking the supply to the heart and causing a heart attack.
“With the potential public health implications of an association between influenza virus infection and acute heart attacks, showing robustness of results in a different study population is important,” said Annemarijn de Boer, according to a SWNS statement.
Annemarijn de Boer and team hope that their study, bolstered by the previous Canadian study, will help emphasize the importance of methods such as vaccination to prevent flu – especially in older adultswho have a higher risk of hospitalization.
The team will present their results at the European Congress of Clinical Microbiology and Infectious Diseases.
ZAP // 
