A new study shows that people diagnosed with the flu are six times more likely to have a heart attack within the first week after testing positive for the flu virus than they were the year before or the year after.
The study was led by Dr. Annemarijn de Boer, together with the Julius Center for Life Sciences and Primary Care at UMC Utrecht in Utrecht, The Netherlands. 2018 survey Canadian researchers found a similarly strong relationship between flu and heart attacks in people hospitalized with heart attacks.
Dr. Annemarine de Boer
The current findings will be presented by de Boer at this year’s European Conference on Clinical Microbiology and Infectious Diseases in Copenhagen, Denmark on April 18th.
de Boer’s team explains that the link between flu and heart attacks lies in the flu virus’ ability to increase the viscosity or clotting of blood. This clotting, along with inflammation from the body’s immune response, can weaken fatty plaques in the arteries. They point out that if the plaque ruptures, it can form a blood clot and cause a heart attack.
“In general, respiratory infections can cause blockages like this,” de Boer said in an interview.
Researchers enhance analysis with mortality data
The aim of this study was to replicate the study by Canadian researcher Kwon and colleagues, but to enhance the analysis by including mortality data across a broader population. It did not include deaths from heart attacks that occurred in .
For a broader analysis, de Boer used laboratory results from 16 laboratories across the Netherlands (covering about 40% of the population), as well as death and hospital records.
In the Netherlands, influenza testing and diagnosis is usually done in hospitals, so the patients under investigation are critically ill, she said.
“Unfortunately, we didn’t get to see flu in the general population,” she said.
Laboratory confirmed 26,221 flu cases between 2008 and 2019. Of the influenza patients, 401 had at least one myocardial infarction within one year of their diagnosis of influenza (419 in total).
Of the 419, 25 occurred within 7 days of influenza diagnosis, 217 within 1 year before diagnosis, and 177 within 1 year of influenza diagnosis (excluding the first 7 days). ).
About a third of people (139 out of 401) died of some cause within a year of their flu diagnosis, the authors write.
Researchers in the Netherlands calculated that study participants were 6.16 times more likely to have a heart attack a week after being diagnosed with the flu than in the years before and after. Canadian researchers found that she was 6.05 times more likely to have a heart attack that week.
However, when the Dutch researchers excluded out-of-hospital mortality data, they got much lower but still significant risk numbers, just as the Canadian researchers did. The risk of seizures was 2.42-fold instead of 6.16-fold.
The reason for the different results when using the same parameters in the data may stem from the fact that outpatient influenza testing is less common in the Netherlands than in Canada.
Researchers say the findings show how imperfect data can lead to different results.
de Boer said it’s important that patients and doctors are aware of this link and be aware of heart attack symptoms.
Dr. Sheriff Mossad, M.D.
Sheriff Mossad, M.D., of the Department of Infectious Diseases at the Cleveland Clinic in Ohio said: Medscape Medical News, “It is not surprising that a Dutch study found that, excluding out-of-hospital deaths, there was only a 2.4-fold increase in heart attacks within one week of influenza diagnosis. , because a small proportion is expected to be due to heart attacks..“
Impact on practice
Mossad said the findings add solid evidence that influenza is not necessarily just a short-term inconvenience. They also support the need for vaccination, he said.
“[This study] It will raise more awareness about the seriousness of the flu and its consequences,” he said.
He pointed out that previous research has shown that influenza infection can exacerbate underlying conditions such as chronic obstructive pulmonary disease, liver and kidney disease, and multiple sclerosis.
Noting that the data was collected before the pandemic, the Mossad said the number of flu patients who had heart attacks during the pandemic was likely even higher than those figures indicated.
At the height of the pandemic, people experiencing chest pain and other symptoms were less likely to come to the hospital, possibly because of fear of contracting COVID-19, he explained.
The author and Dr. Mossad have not reported any relevant financial relationships.
European Conference on Clinical Microbiology and Infectious Diseases. Announced on April 18, 2023. Abstract #4290
Marcia Frellick is a freelance journalist based in Chicago. She previously contributed to Chicago She’s Tribune, Science She’s News, and Nurse.com, and was editor at Chicago She’s the Sun Times, Cincinnati She’s the Enquirer, and St. She’s the Cloud (Minnesota) Times. . Follow her on her Twitter. @mfrellick.
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