A groundbreaking study by scientists in Finland and the UK suggests that heart attacks, also known as myocardial infarctions, may actually be caused by bacterial infections.
This surprising finding could completely change how doctors understand, prevent, and treat heart disease.
For many years, heart attacks have been linked to blocked arteries caused by cholesterol buildup. The traditional view has been that damage starts when the body reacts to oxidized LDL, or “bad” cholesterol. But the new research suggests that something else may also be at play: bacteria hiding inside artery walls.
The study found that the cholesterol-rich plaques in the arteries of people with heart disease may contain biofilms—gel-like layers created by bacteria. These biofilms can stay hidden in the body for years, even decades.
The bacteria inside are dormant, which means they are not active and don’t cause symptoms. Because of the protective biofilm, the immune system can’t detect the bacteria, and antibiotics can’t reach them.
However, a new infection or another type of stress on the body—like a virus—can suddenly activate the bacteria. This sparks inflammation, which weakens the cap of the plaque. The plaque may then rupture, leading to a blood clot (thrombus) and, ultimately, a heart attack.
Professor Pekka Karhunen, who led the study, says that scientists have long suspected bacteria might play a role in heart disease, but strong proof has been lacking until now.
The team found DNA from bacteria normally found in the mouth inside artery plaques. This confirms that bacteria from other parts of the body may travel through the bloodstream and settle in the heart’s arteries.
The research team even created a special antibody to detect these bacteria, which helped them spot hidden biofilms in artery tissue. They found that in cases of heart attack, these bacteria were released from the biofilms. The body’s immune system then launched an attack, causing inflammation and damage to the artery wall.
This discovery may lead to big changes in heart disease treatment. If doctors can confirm bacterial involvement in heart attacks, they may be able to create new tests to detect the risk earlier.
Treatments could also include drugs to stop the bacteria from becoming active. In the future, scientists may even be able to develop a vaccine to prevent certain types of heart disease.
The study was a collaboration between Tampere and Oulu Universities, the Finnish Institute for Health and Welfare, and the University of Oxford. Researchers examined tissue samples from people who had died suddenly of heart attacks and from patients with artery disease who had undergone surgery.
This research is part of a large cardiovascular project funded by the European Union and supported by 11 countries. Additional funding came from the Finnish Foundation for Cardiovascular Research and the Jane and Aatos Erkko Foundation.
The full study, titled “Viridans Streptococcal Biofilm Evades Immune Detection and Contributes to Inflammation and Rupture of Atherosclerotic Plaques,” was published in the Journal of the American Heart Association.
If you care about heart health, please read studies that Changing blood pressure readings is a hidden sign of heart disease and common type 2 diabetes drugs may raise heart risk.
If you care about heart health, please read studies about root cause of heart rhythm disorders and Warning signal from the kidneys can predict future heart failure risk.
Copyright © 2025 Knowridge Science Report. All rights reserved.
