In older adults, the risk of a cardiovascular event was higher for up to three weeks after an infection, according to a new study.
Unhealthy diet, lack of exercise, and smoking cigarettes are all well-known risk factors for cardiovascular disease. So are conditions such as high blood pressure, elevated cholesterol, and type 2 diabetes.
Now a new study adds to that list. Researchers found that in older adults, infection increased the risk of having a coronary event — such as a heart attack — or stroke over the next three months.
The study was published last month in the Journal of the American Heart Association.
Researchers looked at 1,312 cases of coronary heart disease and 727 cases of ischemic stroke, the kind caused by a blood clot. The average age at the time of the event was 75 years.
The data came from a registry of patients tracked over multiple years in four U.S. communities.
The risk of having a coronary heart disease event or stroke was higher in the 90 days after the infection, compared to 1 to 2 years earlier in the same group of patients.
The most common infections were urinary tract infections, and pneumonia or other respiratory infections. Skin and blood infections also occurred.
People in the study had other risk factors for cardiovascular disease, such as high blood pressure or cholesterol, smoking, family history of cardiovascular disease, greater age, and being male.
“Infections are a trigger for people who are already at risk — they develop this acute infection event that triggers the heart attack or the stroke,” said Dr. Kevin Schwarz, a scientist at the Institute for Clinical Evaluative Sciences (ICES) and an assistant professor at the University of Toronto. He was not involved in the study.
Unlike earlier studies, this one also compared inpatient and outpatient infections.
“The risk increased most profoundly in patients who were hospitalized, versus those who were treated as an outpatient,” said Dr. Howard Weintraub, professor of medicine and clinical director of the Center for the Prevention of Cardiovascular Disease at NYU Langone Health. He was not involved in the study.
Some research suggests that the body’s inflammatory response to an infection can encourage the formation of clots in the arteries, which can block the flow of blood to the heart or brain.
The researchers write in the paper that infections that require hospitalization are often more severe, which may cause greater inflammation. This may explain the higher risk, compared to that for outpatients.
But other factors related to hospitalization may be involved, such as extended bedrest or medication changes.
“People who are discharged after an infection frequently go home on different medicines than they were admitted with,” said Weintraub.
He said the changed medications are often high blood pressure or cholesterol medications, which can interact with antibiotics used to treat the infection.
The new study fits with research published earlier this year by Schwartz and colleagues in the New England Journal of Medicine.
They found that acute influenza increased the risk of heart attack for seven days after infection. This was shorter than in the JAHA study, which found an increased risk for up to 90 days.
Weintraub pointed out, though, that in the new study “there was a significant fall in the risk of coronary heart disease or ischemic stroke within the first two weeks.”
Research has also shown a link between cardiovascular disease and inflammatory conditions like rheumatoid arthritis.
Even HIV increases the risk of cardiovascular disease, with some studies suggesting HIV-related inflammation as one possible cause.
Weintraub said that doctors and hospitals treating patients for infections should look at their overall health, not just treating the infection.
“Greater effort should be made to make sure people don’t go home from the hospital without their risk factors for cardiovascular disease being adequately controlled,” he said.
This may mean a visit to their primary care physician or cardiologist within two to four weeks after the infection in order to resume their regular medications. This is especially true for people who were hospitalized for an infection.
In some cases, an infection may remind doctors and their patients to take better care of the risk factors for cardiovascular disease.
“If you have a 70-year-old who hasn’t been on any medicines and there’s been a little bit of inertia on the part of the patient and physician to treat these things, this may be an opportunity to consider treating,” said Weintraub
Schwartz said the results highlight the need for people to stay up-to-date with vaccinations for preventable infections such as influenza and bacterial pneumonia.
“It’s really important for people to get their vaccines, particularly when they’re at risk of complications from infections,” he said.
He added that people at risk should take other steps to avoid getting the flu or pneumonia, such as washing their hands frequently and avoiding close contact with people who are sick.
In older adults, the risk of a having a cardiovascular event such as a heart attack or stroke increased for up to 90 days after an infection.
The risk was higher during the first two to four weeks and for patients who were hospitalized.
Staying up-to-date on flu and pneumonia vaccinations can lower the risk, as can controlling your blood pressure, cholesterol, diabetes, and other cardiovascular risk factors.