Bacterial infection proven to be a cause of myocardial infarction

Myocardial infarction, which for decades was considered exclusively a cardiovascular disease, may be infectious in nature. An international team of researchers from the Universities of Tampere and Oulu, the Finnish Institute for Health and Welfare, and the University of Oxford has presented compelling evidence for the first time that bacteria can trigger a chain of events leading to a heart attack. The findings are published in the Journal of the American Heart Association.

A myocardial infarction is the death of part of the heart muscle. It occurs due to a sudden decrease in blood flow in the coronary artery, the vessel that supplies this area of the heart. Without oxygen and nutrients, the myocardial cells begin to break down. The longer and more severe the blood flow disturbance (ischemia), the more extensive the damage.

Scientists have discovered that bacterial biofilms can remain in atherosclerotic plaques — dense deposits of cholesterol in the arteries — for decades. These gelatinous colonies of microorganisms are well protected from the immune system and antibiotics, so their presence remains undetectable. But when an external factor, such as a viral infection, intervenes, the biofilm “wakes up”: bacteria begin to actively multiply and cause inflammation. The inflammation destroys the plaque membrane, a thrombus forms, and a myocardial infarction develops.

Researchers have found genetic material from several types of bacteria in plaques, including those found in the oral cavity. A new method using specific antibodies has made it possible for the first time to see bacterial structures directly in artery tissue. Moreover, the moment when bacteria are released from the biofilm coincided with the development of a heart attack.

According to the World Health Organization, more than 9 million people worldwide died from ischemic heart disease in 2021 alone. Therefore, understanding the infectious nature of heart attacks opens up prospects for new methods of diagnosis and prevention of one of the leading causes of mortality.