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Flu Shots Help Prevent Heart Attacks and Strokes

By Lisa Collier Cool
November 26, 2012

If you’re tempted to skip your flu shot, consider this: Getting vaccinated cuts risk for a heart attack or stroke by up to 50 percent, according to two studies presented at the Canadian Cardiovascular Congress.

Scientists from TIMU Study Group and Network for Innovation in Clinical Research analyzed published clinical trials involving a total of 3,227 patients, half of whom had been diagnosed with heart disease. Participants, whose average age was 60, were randomly assigned to either receive flu vaccine or a placebo shot, then their health was tracked for 12 months.

Those who got the flu shot were 50 percent less likely to suffer major cardiac events (such as heart attacks or strokes) and 40 percent less likely to die of cardiac causes. Similar trends were found in patients with and without previous heart disease. The findings suggest “that flu vaccine is a heart vaccine,” lead study author Jacob Udell told Fox News.

Why do flu shots help prevent heart attacks? To learn more, I talked to Bradley Bale, MD, medical director of the Heart Health Program for Grace Clinic in Lubbock, Texas.

A number of studies have shown a link between heart attacks and a prior respiratory infection. A 2010 study of about 78,000 patients age 40 or older found that those who had gotten a flu shot in the previous year were 20 percent less likely to suffer a first heart attack, even when such cardiovascular risks as smoking, high cholesterol, hypertension and diabetes were taken in account.

Scarier still, researchers report that up to 91,000 Americans a year die from heart attacks and strokes triggered by flu. This grim statistic prompted the American Heart Association and American College of Cardiology to issue guidelines recommending vaccination for patients with cardiovascular disease (CVD). The CDC advises flu shots for everyone over six months of age, but cautions that certain people should check with a medical provider before being immunized.

Sadly, fewer than half of Americans with high-risk conditions like heart disease get the shot, leaving themselves dangerously unprotected against both flu complications and cardiovascular events. In fact, the CDC actually uses heart attack rates to track seasonal flu outbreaks, says Dr. Bale. “They look for areas with a sudden surge in heart attacks and send a team to investigate, because the cause is almost always a spike in flu cases.”

To picture how flu could ignite a heart attack or stroke in someone with CVD, think of cholesterol plaque as kindling, says Dr. Bale. “Inflammation, which has recently been shown to actually cause heart attacks, is what lights the match, causing plaque to explosively rupture through the arterial wall.”

When a plaque rupture tears the blood vessel lining, the body tries to heal the injury by forming a blood clot. If the clot obstructs a coronary artery, it can trigger a heart attack, while a clot that travels to the brain could ignite an ischemic stroke. It’s a myth that plaque buildup alone sparks heart attacks, since numerous studies have shown that what chokes off flow to the heart is a clot.

“Inflammation is a key player in destabilizing plaque, explaining why some people with relatively little build up in their arteries have heart attacks or stroke, while others with substantial plaque deposits never suffer these events,” says Dr. Bale, who advises all of his patients to get flu shots to guard against inflammation, the body’s response to viral and bacterial infections.

Another surprising benefit of getting a flu shot is reduced risk for pulmonary embolism (a blood clot in the lungs) and deep vein thrombosis (a clot in the legs). A 2008 study found that the threat of developing these problems dropped by 26 percent overall in participants who had been vaccinated in the previous year, with a 48 percent risk reduction in patients younger than 52.

Along with a flu shot, Dr. Bale recommends two other vaccinations to reduce heart attack and stroke risk. If you’re 50 or older and have CVD. If you don’t have plaque in your arteries, you should still get these shots, but at an older age, as discussed below:

The herpes zoster vaccination against shingles. This shot protects against reactivation of the chickenpox virus almost everyone was exposed to during childhood. The virus, which lies dormant in nerve cells, can flare up, typically in older people, and cause a blistering skin rash that can lead to chronic nerve pain. Two large studies report that people who develop shingles are at up to four times higher risk for stroke, highlighting the value of vaccination. While shingles usually targets people who are 60 or older, about 20 percent of cases occur in people ages 50 to 59, which is why Dr. Bale advises being vaccinated at 50 if you have CVD. The CDC recommends the shot for everyone who is 65 or older, and people who are 19 or older and smoke or have asthma.

Vaccination against pneumococcal pneumonia. If you’re 65 or older—or younger with risk factors for pneumonia—such as heart failure, chronic pulmonary disease, or diabetes—the CDC advises being immunized against pneumococcal pneumonia. A study of more than 84,000 people found that those who had been vaccinated were at lower risk for both heart attack and stroke. Given these benefits, Dr. Bale advises heart patients to be immunized at 50.


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