Bacteria as Silent Trigger for Heart Attacks: Scientists Look Beyond Cholesterol as a Culprit

Dormant bacterial biofilms residing in arteries may reactivate and rupture plaques to promote heart attacks

Using advanced techniques, a group of international scientists found that cholesterol and fat deposition inside arteries render common oral bacterial biofilm formation, aggravating heart attack risks upon activation by viral infection.

"Bacterial involvement in coronary artery disease has long been suspected, but direct and convincing evidence has been lacking. Our study demonstrated the presence of genetic material, DNA from several oral bacteria inside atherosclerotic plaques," the lead author, Dr. Pekka Karhunen, explained.

A Research challenging traditional views

Traditionally, cholesterol, physical inactivity, unhealthy diet, alcohol, and tobacco are believed to be the main culprits of heart attacks. However, modern techniques demonstrated that atherosclerotic plaques comprising cholesterol may provide bacteria an ideal platform for building gelatinous, asymptomatic biofilm over the years. Neither the patient’s immune system nor antibiotics penetrates the biofilm matrix, shielding bacteria from remaining in the dormant phase. 

In case of viral infection or other external trigger, the biofilm gets activated, causing bacterial proliferation and inflammation inside the body. Subsequently, the fibrous cap of the plaque gets ruptured, leading to blood clotting inside the artery, promoting heart attacks.  

Antibodies Reveal the Silent Killers

Researchers from Tampere and Oulu Universities, Finnish Institute for Health and Welfare, in association with the University of Oxford, conducted the study. For this groundbreaking research, tissue samples were collected from patients who died from sudden heart attacks along with individuals undergoing surgery to remove atherosclerotic plaques or excess cholesterol deposition in carotid and peripheral arteries. 

To validate their observations, scientists designed antibodies specific to the bacteria detected in the plaques, which revealed biofilm structures in arterial tissue. In patients with myocardial infarction, bacteria were observed to have emerged from the biofilm, stimulating the inflammatory process and plaque rupture.

Rethinking Heart Attack Prevention

Global survey confirms heart attack as a major cause of around 20 million annual deaths from cardiovascular illness. Among many, two major highlights of the study are the direct link between oral bacteria promoting risks of heart attacks and the contribution of secondary infections like viral illness. The findings suggest a whole new approach to diagnosing individuals at higher risk of myocardial infarction. 

The researchers believe that bacterial biofilms could become a target for state-of-the-art diagnostic and therapeutic interventions. Developing vaccines against those bacterial colonies is a likely scenario. However, such applications would require detailed preclinical and clinical investigation.