Pekka KarhunenA professor at Tampere University, he spent years analyzing heart tissue samples taken from people who died suddenly. In those fragments of myocardium, he found something that forever changed his view of heart attacks: bacterial DNA that shouldn't have been there. A discovery that is rewriting cardiology textbooks and could pave the way for vaccines against a significant percentage of heart attacks.
When the myocardium becomes a refuge for bacteria
The study published in the Journal of the American Heart Association He analyzed coronary plaques from 121 people who died suddenly and surgical samples from 96 patients who underwent endarterectomy. The results are striking: 42,1% of coronary plaques contained viridans streptococcal DNA, bacteria commonly found in our mouth. Percentage that rises to 42,9% in surgical samples.
“Bacterial involvement in coronary artery disease has been suspected for a long time, but direct and convincing evidence has been lacking,” explains Karhunen.
“Our study demonstrated the presence of genetic material from various oral bacteria within atherosclerotic plaques affecting the myocardium.”
Bacteria organize themselves into gelatinous biofilms, protective structures that make them invisible to the immune system and resistant to antibiotics. As recent studies on biofilms demonstrate, these microorganisms can remain dormant for decades, waiting for the right moment to become active.
The hidden mechanism of heart attack
The process that leads to bacterial heart attacks no longer holds any secrets. Streptococcus viridans They colonize the lipid core of atherosclerotic plaques, forming biofilms that completely evade the macrophages of the innate immune system. It's a bit like an underground city thriving beneath a metropolis, unaware of the presence of these silent inhabitants.
But the calm is apparent. When an external trigger (a viral infection, stress, trauma) activates the biofilm, the bacteria multiply and release a more virulent "new generation." These more aggressive bacteria abandon the safe haven of the biofilm and infiltrate the fibrous layer of plaque, the thin barrier that keeps cholesterol buildup stable.
At that point, the immune alarm goes off. The adaptive immune system finally recognizes the invasion and unleashes a massive inflammatory response. The inflammation weakens the fibrous layer until it ruptures, exposing the plaque's contents to the bloodstream. A clot forms, the artery becomes blocked, and the myocardium stops receiving oxygen. This is a heart attack.
From the mouth to the myocardium: a dangerous journey
Streptococci viridans These are bacteria that normally inhabit the oral cavity. They are part of the natural microbiota and, under normal conditions, do not cause problems. But under certain circumstances, they can embark on a treacherous journey to the heart. During dental procedures, aggressive tooth brushing, or even simple episodes of transient bacteremia, these microorganisms enter the bloodstream.
Atherosclerotic plaques develop new blood vessels due to local hypoxia. These small vascular channels become prime entry points for circulating bacteria. Once established, the long wait begins. The biofilm grows slowly, protecting its inhabitants and allowing them to multiply undisturbed.
The study demonstrated a statistically significant correlation between presence of viridans streptococci and death from coronary heart disease (P=0.021) or myocardial infarction (P=0.042). The more severe the atherosclerosis, the greater the likelihood of finding these bacteria in the plaque.
Implications for the future
If confirmed by larger studies, this paradigm will radically change the approach to cardiovascular prevention. Oral hygiene, already important for general health, will play a crucial role in preventing heart attacks. Regular dental checkups, timely treatment of oral infections, and the wise use of antibiotics could also become tools for cardiac prevention, saving countless lives.
But the most fascinating prospects concern the development of new therapies. Specific vaccines against viridans streptococci They could prevent plaque colonization. Advanced imaging techniques could identify the presence of biofilms in the arteries before they become active. Targeted antibiotics could be used in the acute phase to limit the inflammatory response.
The research team, which includes collaborators fromUniversity of Oulu, From 'Finnish Institute for Health and Welfare and by 'Oxford University, is already exploring these possibilities. The project, funded by the European Union and Finnish foundations, represents an example of how collaborative research can lead to paradigm-shifting discoveries.
A question of balance
The discovery, of course, does not suggest that all heart attacks are infectious. Cholesterol, hypertension, smoking, and a sedentary lifestyle remain key risk factors. Rather, it adds a piece to the complex puzzle of atherosclerosis, demonstrating how different mechanisms can interact to cause acute cardiovascular events.
The myocardium, that tireless muscle that beats over 100.000 times a day, is more vulnerable than we imagined. But perhaps this very vulnerability offers us new opportunities to protect it. Because understanding an enemy is the first step to defeating it.
And if brushing your teeth properly could actually save your heart, it would be one of the simplest and most cost-effective preventative measures in the history of medicine.
