How the flu increases your risk of heart attack

Influenza and heart attack are things we don’t normally associate together, but the two are more connected than you might think.

A recent study found that a person’s chances of having a heart attack, or myocardial infarction, increase significantly after a flu diagnosis. In the study, people who had been diagnosed with the flu in the last seven days were six times more likely to have a heart attack than people in the control group who were not diagnosed with the flu.

This study further points out what we already know — that influenza is very stressful for your body.

The connection between flu, pneumonia and heart attack

Anything that stresses the body can affect the heart. There are many possible ways the stress of an illness like the flu can provoke a heart attack, especially in already susceptible populations. For patients who have significantly blocked arteries, the flu can put extreme demand on the heart that the supply/demand mismatch can cause heart damage. What is less clear is whether the activation of the inflammatory response could also destabilize mild plaques and cause them to rupture and lead to a heart attack.

This same scenario applies to flu-induced pneumonia. Influenza affects the natural defenses we have in our lungs to protect against bacterial infections, and can therefore lead to pneumonia.  This is very stressful for the heart and can lead to the same supply/demand mismatch type of heart attack.

Although this could happen to anyone, there is no question that patients whose immune systems are compromised, especially older patients, are at the highest risk of both the flu and potential complications. Comorbid conditions such as COPD, renal insufficiency or diabetes tend to weaken the body’s ability to defend against infections of any sort, and the immune response tends to be muted as well.

How to lower your risk

Everyone needs to be aware, even the healthiest of people, that influenza is a very serious infection. It can lead to pneumonia or other systemic bacterial infections that can then lead to sepsis (widespread bacterial infections associated with toxic complications) and respiratory failure or pneumonia.

As this new study shows, that can put a person in increased danger of a heart attack.

The most important way to deal with influenza is prevention. That means hand sanitizing when touching anyone else’s hands or face as well as anything inanimate in a public place.  We should remember to always wash our hands prior to touching our face. This is the singular most important way to avoid the transmission of influenza.

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The flu vaccine is another incredibly important way to protect yourself from influenza. Although the vaccine is not always as successful as we hope, it is our first line of defense against a very contagious illness. It can also decrease the severity of your illness if you do get the flu. If you think have been exposed to influenza, Tamiflu can help reduce the duration and severity of influenza, as well as potentially decrease the risk of pneumonia. Make sure you know what to do if you or a loved one gets the flu.

Although it would be hard to therefore conclude that prevention of influenza would directly decrease the risk of heart attack, it would likely follow that anything we can do to minimize the risk of flu and pneumonia would also decrease the risk of a heart attack.

With all the potentially life-threatening complications, it’s clear that illnesses like the flu and pneumonia are hard on your body — especially your heart. So, when it comes to the flu, take every precaution you can and don’t hesitate to get care if you feel unwell.

Make sure you’re prepared — keep your heart healthy and know your risk of heart disease.

About the author

Michael Sills, MD
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Michael Sills, MD, is a cardiologist on the medical staff at Baylor Scott & White Heart and Vascular Hospital – Dallas. His clinical interests include diagnostic and preventive cardiology as well as cardiac imaging. He is an avid runner, chef and proud grandfather. Get to know Dr. Sills.

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How the flu increases your risk of heart attack