The Flu and Heart Disease

Things Heart Patients Should Know about the Flu

Many people don’t get flu vaccinations or  don’t really worry about getting the flu. However flu season poses special problems for heart patients.  The flu viruses might act as triggers for heart attacks in cardiovascular patients. It also triggers high blood sugars in the diabetics as a result of the stress of illness which then increases heart stress. It often takes longer to recovery from in heart patients and can be more serious with more complications. Here is what the American Heart Association reports on how the flu affects the heart.

The flu can leave most people sick for a few days, but it can be a much more serious ordeal if you have heart disease or have had a stroke.

In fact, the flu can cause complications, including bacterial pneumonia, or the worsening of chronic heart problems.

“It’s more stress on your heart. It has to work harder to pump blood through your lungs,” said Donna Arnett, Ph .D ., chair and professor of epidemiology at the School of Public Heath at the University of Alabama at Birmingham and the president of the American Heart Association.

Because of potential complications, which can sometimes lead to death when a patient is already sick, it becomes even more important to avoid the flu if you have heart disease and as you get older, Dr. Arnett said.



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.

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.”

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.

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.


Doctors have long known that flu viruses can worsen existing medical conditions and that heart patients are especially vulnerable during flu outbreaks. Flu viruses cause inflammation in the body, usually in the lungs. But they can also cause swelling in the heart itself or in the coronary arteries, which could lead to dangerous clots breaking off and causing a heart attack.

Seek medical care if you or the person you are caring for

  • has chest pain or difficulty breathing
  • has purple or blue discoloration of the lips
  • suddenly becomes dizzy
  • has severe or persistent diarrhea or vomiting and is unable to keep liquids down
  • is confused or isn’t responsive.

Returning to Exercise After Being Sick

If you have been exercising regularly and get sick it is important you return back to activity gradually. My experience working in Cardiac Rehabilitation when a patient had problems frequently they were trying to return to strenuous exercise too soon following illness. The risk of a serious cardiovascular event (heart attack or stroke) is doubled in the week following a serious respiratory infection, such as flu or acute bronchitis. This is according to a report in the European Heart Journal.

If you are coming down with an illness such as the flu, it is best not to exercise. Your body needs to use its energy to overcome the illness.  Exercising strenuously is like burning the candle at both ends.  The body doesn’t have the energy to fight illness, so the illness takes longer to overcome. There is also evidence you can drive a virus deeper into the system making it much harder to overcome.

 Never exercise if feverish.

A fever indicates your body is fighting an infection.  Exercise can cause your body temperature to rise dangerously high and lead to  heat stroke. This can also  lead to dangerous dehydration and even heart failure.

Good advice is when returning to exercise, work out one day at a low intensity for every two days you were ill.

I tell patients to cut their intensity to 50% of what they normally do, and start back with a short duration say no more than 20 minutes. Use the two-hour rule. You should feel fully recovered two hours after exercise. If you are exhausted for the remainder of the day it is too much on your body. It should take at least two full weeks to build back up following a nasty cold or flu bug.  Drink plenty of water during this time to help thin any mucus secretions from the lungs, this helps your body to expel these. If you had to take antibiotics be aware that some antibiotics   –  Cipro and Levaquin –  are known to increase the likelihood of muscle rupture, therefore go slow and  gently stretch.

There is no such thing as “sweating out” toxins, germs or viruses. Put all your energy towards resting and getting well.

Nausea Vomiting / Diarrhea

 These can cause dehydration and electrolyte imbalances. Wait to exercise until the symptoms have stopped completely  or 24 to 48 hours and you are re hydrated. One way to know if properly re hydrated is looking at the color of your urine. If the urine is bright yellow you are not hydrated. The color should be a very pale yellow. Also look at the skin on the back of your hand and give it a pinch. Does the skin stay up for several seconds, or does it quickly go back down. It should quickly go back down.  Electrolyte depletion can be very serious in heart patients, especially those on diuretics.  If in doubt or concerned ask your physician to draw electrolytes.  A weak 50%water to 50% electrolyte drink such as Power aid, or Gator Aid might be advisable.  Of course eating a banana which is easier on the belly than something like orange juice, also helps.

Most importantly listen to your body, go slow, give yourself the time to heal. Stop exercise if you notice your heart racing, shortness of breath, chest discomfort, weakness.


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