People hospitalized for infections — almost any infections — are at substantially increased risk years later for heart failure, according to collaborative research by the University of Minnesota and Mayo Clinic.

The study of more than 14,000 people over two decades doesn’t establish cause and effect, but advocates said Thursday that it establishes a strong enough correlation that people should take heed and try to reduce their infection risks.

“These are ‘sit-up and take notice’ findings,” said Sean Coady, a deputy branch chief for cardiovascular sciences at the National Institutes of Health’s National Heart, Lung, and Blood Institute.

Heart failure, which affects 6.7 million Americans, is a weakening of the heart that prevents it from pumping sufficient blood and oxygen. Researchers were surprised to find that hospitalizations resulting from common skin and urinary tract infections increased heart failure risks, alongside respiratory infections such as influenza and blood infections such as sepsis.

That suggests that the body’s response to infection is a big part of the heart failure risk, said Ryan Demmer, an epidemiologist who led the study at the U and continued it after he moved to Mayo in 2023.

“There’s some notion that really severe infections sort of turn on the immune system in a way where it just doesn’t quite turn off, and it stays revved up, possibly for many years,” he said.

Other possibilities include that serious infections cause genetic or biological changes that lay dormant after hospitalizations but emerge later in life to cause heart failure, he said. Other studies have found hospitalizations increase risks of health problems later in life, so Demmer said it’s possible infections are driving people to as-yet unknown risks from those hospital visits.

Even without cause and effect established, Demmer said the results should encourage people to prevent infections through vaccines and good hygiene. People who have already been hospitalized because of infections can talk with their doctors about ways to reduce cardiac risks.

The findings are the latest from a surveillance program called Atherosclerosis Risk In Communities (ARIC), which enrolled thousands of people at around age 54 in the late 1980s from the Minneapolis area and three other U.S. sites. Researchers followed up with them two to three decades later to see how their health changed.

Demmer and colleagues had already discovered in 2023 that infection-related hospitalizations increased the risk for dementia later in life.

Over the course of three decades, about 1 in 4 people in the surveillance program suffered episodes of heart failure. The risk was more than twice as likely among patients who at some point had been hospitalized for infections, according to the latest study by Demmer’s group, published Thursday in the Journal of the American Heart Association.

Risks were highest following bloodstream and respiratory infections, but were also significant for skin and urinary tract infections. Digestive infections were only weakly correlated with heart failure later in life.

Heart failure can lead to cardiac arrest or damage the kidney and liver. Treatments range from medications to increase blood flow to surgeries to implant pacemakers or remove obstructions in blood vessels.

Establishing a precise cause-and-effect relationship between infections and heart failure will be difficult, because researchers can’t deny preventive care to patients just to see if it increases their risks, Demmer said. “It would be unethical, for example, to say we want to randomize people to receive or not receive the flu vaccine.”

Instead, Demmer said he has been studying whether it improves outcomes to add infection-related hospitalizations to calculators that assess patients' risks for cardiac episodes and their need for preventive treatments.

The study period predated the pandemic, but Demmer said COVID-19 is likely to increase heart failure risks as well.

In Minnesota, COVID-19 has caused more than 100,000 hospitalizations over the past five years and has lingered post-pandemic, causing more than 3,200 hospitalizations since the end of September. Influenza also has sent more than 4,200 people to hospitals in that time, especially after Christmas when hospitals reported that their emergency rooms were overwhelmed.

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