A new study links bacteria found in the mouth to heart attacks. Does this mean heart attacks could be infectious? The findings are not that simple, but they are noteworthy and they add another reason not to skip brushing your teeth at night.
Below, experts explain the research, connect it to earlier studies and share practical takeaways for whole-body heart health.
What did the study find?
In a Finnish study published in a peer-reviewed cardiology journal, researchers evaluated 121 autopsies from people who died suddenly due to heart attack and 96 patients undergoing surgery to clear blocked arteries. They sampled and analysed coronary plaques—the cholesterol-rich deposits on artery walls—from both groups. Using genetic and microbiological techniques, they examined the plaques for bacterial DNA and signs of immune response to those bacteria, explains cardiologist Dr Elizabeth Klodas.
Researchers detected bacterial DNA from viridans streptococci—microbes commonly found in the mouth and gut—in more than 40% of plaque samples from both groups. By contrast, normal, non-atherosclerotic arteries tend to harbour fewer bacteria, says interventional cardiologist Dr Deepak Ravi.
The bacteria were largely organised as biofilms embedded in the arterial wall, allowing them to lie dormant and evade immune defences. In some cases, “more virulent organisms may escape the biofilm and induce a strong inflammatory response,” Ravi says, a process that could contribute to plaque rupture and trigger a heart attack. “These findings add to our understanding of what causes heart attacks and may lead to new ways to diagnose, prevent and treat them,” adds preventive cardiologist Dr Tracy Paeschke.
Even so, the results do not prove causation. Bacteria may be one piece of the puzzle. As Dr Klodas, puts it, they “do not appear to be just innocent bystanders.” The main drivers of heart disease remain chronic inflammatory conditions such as high cholesterol, high blood pressure and high blood glucose.
What the findings mean
Put simply, “this study establishes a link between infectious disease and heart disease,” says Dr Ravi. Because the bacteria identified are often found in the mouth, they may enter the bloodstream during dental procedures such as root canal treatment, tooth extraction or dental plaque removal. Other infections that seed bacteria into the bloodstream, including skin infections or pneumonia, may also raise the risk of atherosclerotic coronary artery disease, he notes.
This is not the first exploration of bacteria in cardiac events. “Attempts over several decades to treat atherosclerosis by targeting infections—including broad antibiotic trials—have largely failed,” explains cardiologist Dr Ernst von Schwarz.
Ravi adds, “This does not mean routine antibiotics would prevent coronary artery disease or heart attack. In fact, studies of long-term antibiotics for chronic dental infections showed no reduction in cardiovascular events.” Dr Klodas agrees. “I would caution against thinking antibiotics could cure heart disease or prevent heart attacks, and I would certainly not start a course of antibiotics based on this study.”
If future research replicates these findings, anti-infective strategies may be considered alongside proven approaches—eating a heart-healthy diet, being physically active and not smoking.
How to take care of your heart health and oral health
There is more to learn, but the findings are a reminder that body systems are interconnected, says Dr Klodas. They also reinforce the value of good oral and cardiac habits. “Regular dental check-ups plus twice-daily brushing and flossing support mouth health and heart health,” Klodas says. Dr Paeschke recommends brushing twice daily for at least two minutes, preferably with an electric toothbrush.
Above all, heart-healthy habits go the distance. “Bacteria appear to colonise plaque. Less plaque means fewer places for bacteria to live. Your best defence against heart disease is a good offence,” Klodas says. Prioritise a fibre-rich, balanced diet of vegetables, legumes, whole grains and lean proteins, aim for at least 150 minutes of exercise per week, avoid smoking and limit alcohol. “Heart disease remains our leading cause of death, even though much of it is preventable,” Dr Klodas says. “The fundamentals are still fundamental.”
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