Despite a difficult season, most people experiencing this year’s flu – body aches, cough, sore throat and congestion – feel better in a week or two. In more severe cases, the flu virus can lead to complications, such as respiratory infections or pneumonia. And now research is confirming the flu can also lead to heart attack, according to a study  published recently in the New England Journal of Medicine (NEJM).
“Over the last few weeks, we’ve been seeing a lot of patients with myocardial infarctions and positive cardiac enzymes,” said Harry Aldrich, M.D. , medical director of cardiology with Miami Cardiac & Vascular Institute  at South Miami Hospital . “This study validates the anecdotal knowledge that cardiologists have long experienced during flu seasons.”
The research study, conducted in Canada, found hospital admissions for myocardial infarction, commonly known as heart attack, were six times higher within the first week of testing positive for the flu. The positive flu results were from respiratory specimens, allowing the researchers to mark a significant association between acute respiratory infections and heart attack.
“Most of the patients who have a heart attack after the flu have underlying heart disease that automatically puts them at risk of more complications,” Dr. Aldrich says.
Among U.S. adults with an underlying condition hospitalized due to the flu this season, cardiovascular disease is one of the most common, according to the U.S. Centers for Disease Control and Prevention (CDC) .
Data from the Canadian study also support this. Twenty-four percent of the adult patients had a previous hospitalization for heart attack and many had established cardiovascular risk factors: 49 percent had diabetes, 38 percent had elevated cholesterol levels and 85 percent had high blood pressure. Most of the patients studied who had a heart attack after the flu were older than 65.
Flu infection in the elderly is associated with a high occurrence of acute heart failure, according to research published last year in the medical journal Heart Failure Reviews .
Heart Disease and Flu
Even in otherwise healthy adults, the flu causes a lot of inflammation in the body, Dr. Aldrich says. But flu-related inflammation in people with heart disease is more serious. It can cause acute coronary syndrome, he explains.
“When the flu causes systematic inflammation, there can be inflammation on the internal lining of arteries,” Dr. Aldrich said. “This inflammation in a patient who has heart disease can cause plaque that has built up in the arteries to rupture, leading to a heart attack.”
The other complication from flu that can seriously affect heart disease patients is pneumonia, he says.
“The respiratory system in a patient with heart disease is already compromised,” Dr. Aldrich said. “So when they get a severe case of the flu, they often develop severe pneumonia and need to be hospitalized.”
Reducing Risk of Heart Attack After Flu
So what can people do to reduce the risk of heart attack caused by the flu?
“First and foremost, everyone should get a flu shot,” said Dr. Aldrich. “I tell all my patients to get a flu shot, but everyone, even those who are otherwise healthy without heart disease, should get vaccinated.”
Second, Dr. Aldrich recommends people with heart disease also get a pneumococcal vaccine, most importantly those who are age 65 and older and for people with congestive heart failure, asthma or diabetes.
“Flu can make people more vulnerable to secondary infections like bacterial pneumonia, so we recommend people 65 and over get the pneumococcal pneumonia vaccine,” said Dr. Anne Schuchat, CDC Acting Director, during the agency’s most recent briefing about widespread flu activity.
“People age 65 and older have an increased risk of dying from a cardiovascular event, and that risk is even greater if they get the flu,” Dr. Aldrich said.
Thirdly, he says, if you develop a high fever, muscle pain, cough and other respiratory symptoms typical of the flu, call your physician within the first 24 hours. Your physician can prescribe antiviral medication that can help lessen the severity of your symptoms.
Paying attention to the type of symptoms and what part of the body they are coming from is key, Dr. Aldrich advised.
“If within the first week of getting the flu you start to have chest pain that’s persistent and not related to muscular aches from coughing, be sure to call or see a doctor right away,” Dr. Aldrich said.