The list of reasons to avoid the flu is long, from the misery of even a mild case to the hundreds of thousands of people hospitalized each year. Here’s another: The flu can lead to cardiac events like heart attack.

In fact, one study found that patients are six times more likely to have a heart attack the week after flu infection.

Tracy Patel, MD, associate medical director of Cottage Grove Cardiology in Bloomfield, explains why — and what to look for.

> Connect with a Cardiologist at Cottage Grove In Bloomfield

What’s behind the flu and heart issues?

COVID showed us how a virus that seems to start in one place can have domino effects throughout the body. That’s true for the flu too.

“The flu can affect the heart in many ways,” says Dr. Patel.

For example, a bad case of the flu can:

  • Increase inflammation throughout your body
  • Lower your oxygen levels
  • Raise your heart rate

A bad case of the flu can affect the heart’s blood supply, causing heart attack.

All of the above — inflammation, lower oxygen, and an elevated heart rate — can decrease the blood supply to your heart. That, in turn, can cause what’s known as a “demand heart attack”: no blockages, but the heart needs more oxygen than it’s getting.

“This is often seen in patients with preexisting heart conditions,” says Dr. Patel.

> Related: 10 “Silent” Signs of a Heart Attack That You Should Know

The flu can cause, or worsen, heart rhythm problems.

Heart rhythm conditions like atrial fibrillation (AFib) and supraventricular tachycardia (SVT) affect millions of people in the U.S. These conditions are often kept under control with medication and other treatments — but a bad flu can trigger an episode.

“The increased inflammation and low oxygen from flu infection can aggravate arrhythmia,” explains Dr. Patel.

> Related: 8 Signs You Might Have a Heart Arrhythmia

Influenza can affect the heart muscle itself.

Along with inflaming muscle tissue throughout your body, “the flu can inflame your heart muscle itself — a condition called myocarditis,” says Dr. Patel.

Most cases of myocarditis resolve on their own. But in severe cases, it can cause heart failure.

It can also inflame the lining around your heart.

The heart is enclosed in a thin, fluid-filled sac called the pericardium. A bad flu infection can inflame this lining too.

“When the pericardium becomes inflamed, it causes a particular type of chest pain,” says Dr. Patel. It can also lead to heart failure.

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Who’s at risk for heart issues from the flu?

You’re at the highest risk if you have:

  • Preexisting heart conditions
  • Advanced age
  • Tobacco use
  • Diabetes
  • Kidney disease

If you have any of these symptoms, call 911.

“If you feel worse than a general virus, and notice any of the following symptoms, get medical attention immediately,” says Dr. Patel.

When to call 911:

  • Chest pressure beyond what you’d usually feel with a bad cough
  • Unable to catch your breath, even with minimal activity
  • Unable to breath when lying flat
  • Significant chest pain when lying flat
  • Lightheaded
  • Heart racing with irregularity

To prevent flu-related heart issues, get a flu shot and follow doctor’s orders.

Then follow the healthy habits we all know so well: “Avoid sick contacts and crowds, and mask up if you have to. And wash your hands,” says Dr. Patel.

If you’ve done all of the above, and you still get the flu, you’ll be at far less risk of severe illness — and flu-related cardiac events.

That belongs on another long list: reasons to stay on top of your health.