Study raises alarm: Influenza infection dramatically increases heart attack risk

This is the alarming result of a Dutch study that was recently published in the “New England Journal – Evidence”. It has long been known that influenza can trigger acute cardiovascular disease. But for the first time, Annemarijn de Boer (University Medical Center Utrecht) and her co-authors have been able to prove the probable connection between influenza and the risk of heart attack in people whose infection had been clearly confirmed by PCR tests in 16 medical laboratories in the Netherlands.

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The risk assessment was performed for the period of one year before and one year after influenza illness (control period) compared to up to seven days after the positive laboratory test (risk period). “Between 2008 and 2019, we identified 158,777 PCR tests for influenza in the study population involved, of which 26,221 were positive and 23,405 corresponded to individual influenza illnesses. (…) The relative frequency of acute myocardial infarction during the risk period (acute influenza infection; note) compared to the control period was 6.16 times higher. The relative frequency of acute myocardial infarction in people without previous hospitalization for coronary heart disease was 16.60 times higher,” the experts wrote in the scientific journal (DOI: 10.1056/EVIDoa2300361).

Influenza vaccination as an option

People who had previously been hospitalized for coronary artery disease, on the other hand, had a risk of heart attack that was “only” 1.43 times higher. This risk may be due to the fact that such patients are often prescribed blood-clotting-inhibiting medications. Infections with the respiratory syncytial virus (RSV) or other viral respiratory diseases also showed a higher risk of heart attack.

British epidemiologist Raina MacIntyre wrote in a commentary that the results were consistent with the observation that ten percent of heart attack patients are also diagnosed with influenza, at least during flu season. The influenza vaccination should also be seen as a way to reduce the risk of heart attack associated with such an illness. The study was funded by the Dutch Research Fund.