Yet another study is strengthening the connection between oral and overall health — this time suggesting that heart attacks may partly be an infectious disease.
Researchers from Finland and the UK, writing in the Journal of the American Heart Association (JAHA), report they found bacterial DNA from common oral species inside arterial plaques. Their findings, Tampere University said, demonstrate for the first time that “myocardial infarction may be an infectious disease.”
The study examined arterial plaques collected from more than 200 patients with coronary artery disease. According to Pekka Karhunen, professor of forensic medicine at Tampere University, bacterial involvement in heart 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 said.
Related: A Healthy Mouth – A Healthier Heart
Viridans streptococci harmless in the mouth
The most frequent bacterial DNA detected belonged to oral viridans streptococci, a group of bacteria usually harmless in the mouth where they form part of dental plaque. However, they are also among the most common pathogens behind infective endocarditis, a serious heart infection linked to biofilms.
Researchers detected viridans streptococcal DNA in 42.1 per cent of autopsy-obtained coronary plaques and in 42.9 per cent of surgical samples. Overall, bacterial DNA was identified in 65.7 per cent of coronary plaques from autopsies and 57.9 per cent of plaques removed during surgery. Other oral pathogens — including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Prevotella intermedia — were also detected.
Building on decades of suspicion
The possibility that infections could drive chronic inflammation in coronary plaques dates back to the 1980s, when researchers linked Chlamydia pneumoniae antibodies and chronic dental infections to myocardial infarction.
The new study adds weight to that theory, showing bacterial biofilms may lie dormant in arterial walls, resisting antibiotics and the body’s immune system. Under certain conditions, the biofilms may release virulent bacteria, triggering plaque rupture and heart attack.
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Global effort
The research was conducted by Tampere and Oulu Universities, the Finnish Institute for Health and Welfare and the University of Oxford. Samples came from individuals who had died suddenly of cardiac causes and from patients undergoing vascular surgery.
It is part of an EU-funded cardiovascular project involving 11 countries, with additional support from the Finnish Foundation for Cardiovascular Research and the Jane and Aatos Erkko Foundation.
While more studies are needed, the findings reinforce the link between oral hygiene and systemic health — underscoring the importance of preventing and managing oral infections.