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Can an infection give you a heart attack?

When you have an infection such as gum disease or pneumonia, chances are you’re most concerned about the symptoms you’re experiencing at the moment. However, mounting evidence suggests that the way the human body reacts to a bacterial or viral infection may put patients at increased risk for heart attack.

When an infection is present, the affected blood vessels and surrounding tissues become inflamed. The signs are redness, swelling, pain and warmth, although they don’t always occur together. Scientists are finding that infections that occur in the mouth, lungs or stomach can cause inflammation not only locally but also in the bloodstream.

Inflammation is the body’s way of signaling the immune system to send infection-fighting cells to a site. However, many scientists now believe that when inflammation occurs in the blood vessels, a dangerous chain of events can be set in motion. The leading suspects are, ironically, the very cells that help the body fight infection.

One theory is that infection-fighting cells release certain chemicals that encourage the growth of plaque (fatty deposits) on artery walls. Blood vessels become narrowed in the spots where plaque collects, increasing the odds that blood flow to the heart may, at some point, become totally blocked. The end result: a heart attack. Another theory is that chemicals released by infection-fighting cells increase the odds that existing plaque will break away as a clot, after which it may become lodged in an artery, blocking blood flow and causing a heart attack.

A 1997 Harvard study supports a possible link between infection and heart attacks. Researchers measured patients’ blood levels of C-reactive protein (CRP), which is released during inflammation. Those men with the highest blood levels of CRP at the start of the study had three times as many heart attacks during six years of follow-up as those men who had the lowest levels of CRP when the study began.

Similarly, a 1998 study showed that women with the highest levels of CRP were five times as likely to experience heart attack and stroke as women with the lowest levels of CRP.

What does this mean to you? The bad news is that the bacteria that cause such common infections as periodontal disease, stomach ulcers, bronchitis and pneumonia may increase a person’s risk of heart attack.

The good news is that aspirin, a drug that many heart-disease patients already take because it helps to prevent blood clots, appears to reduce inflammation in the bloodstream. In recently released guidelines, the American Heart Association recommends low-dose aspirin therapy be considered for anyone with a 10 percent or greater risk of developing cardiovascular disease over the next ten years. All women over age 65, even those with no other risk factors, should discuss aspirin therapy with their doctors.

A proven link between infection and heart attacks would mean that antibiotics, commonly used to treat bacterial infections, may become a treatment option for patients with heart disease. Already, antibiotics have been shown to reduce inflammation in the bloodstream.

However, researchers have yet to prove that antibiotics actually can prevent heart attacks. Even if that link is made, it’s unlikely doctors will start prescribing antibiotics to all patients with risk factors for heart disease.

Why? Because the liberal use of antibiotics already has allowed some infectious organisms to evolve in ways that have made them immune to antibiotics, leaving doctors with no effective treatment for these “super bugs.”

In the future, drugs that fight inflammation in the bloodstream may turn out to be treatment options for some patients with heart disease. Even so, experts recommend that people continue to focus on controlling such established risk factors as high cholesterol, high blood pressure, excess weight, sedentary lifestyle, smoking and diabetes.