12/11/2025
Can you catch a heart attack?” A new study suggests hidden bacterial biofilms can lurk silently inside arterial plaque for decades, shielded from the immune system until a viral illness or other trigger awakens them. Once activated, the bacteria fuel inflammation that ruptures vulnerable plaques and blocks blood flow, leading to a heart attack.
Specifically, researchers report that viridans-group streptococci (common oral bacteria) are embedded as biofilms inside human atherosclerotic plaques, where they can hide from immune surveillance. When these biofilms disperse, they appear to trigger local innate-immune activation and inflammation, plausibly weakening the plaque fibrous cap and promoting rupture—the immediate event behind many myocardial infarctions, especially in men. The team detected viridans streptococcal DNA frequently within plaques and outlined a mechanistic model of biofilm-driven, immune-evading persistence with episodic activation that may precipitate rupture.
Prior supporting evidence makes this discovery credible. For example, bacterial DNA was identified in coronary thrombus aspirates from heart attack patients. Also, large reviews highlight the links between periodontitis and cardiovascular disease, detailing plausible pathways (bacteraemia, endotoxins, molecular mimicry etc) and frequent detection of periodontal pathogens within vascular tissue.
Professor Pekka Karhunen, the study’s lead author, explains that until now it was widely believed that coronary artery disease was primarily driven by oxidised low-density lipoprotein (LDL), which the body identifies as a foreign substance.
The study was conducted by Tampere and Oulu Universities, Finnish Institute for Health and Welfare and the University of Oxford. Tissue samples were obtained from individuals who had died from sudden cardiac death, as well as from patients with atherosclerosis who were undergoing surgery to cleanse carotid and peripheral arteries.
“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,” Karhunen explains.
This study provides a mechanistic link to oral health and periodontitis management as a key cardiovascular risk-modifying strategy. See my recent posting on licorice.
It should be kept in mind that while the ‘biofilm → dispersal → rupture’ model is compelling, direct real-time observation in human plaques is impossible.
Specifically, bacterial dispersal might be a consequence rather than a cause of fibrous cap weakening.
For more information see: https://scitechdaily.com/heart-attacks-may-be-infectious-and-vaccines-could-prevent-them/
and
https://pubmed.ncbi.nlm.nih.gov/40767295/