Heart Attacks May Be Triggered By Infections, Not Just Cholesterol: Study

Scientists in Finland and the United Kingdom have found new evidence suggesting that heart attacks might not just be caused by cholesterol or poor lifestyle, but also by infections.

The study, led by Professor Pekka Karhunen, discovered that a viral infection or an external trigger can activate the bacteria hiding in the biofilms inside artery plaques. These bacteria stay dormant and protected from the immune system for decades. Once active, the bacteria multiply and cause inflammation, according to the report published in ScienceDaily.

The researchers conducted the study at Tampere University and Oulu University in Finland, the Finnish Institute for Health and Welfare, and the University of Oxford in the UK.

The findings stated that this inflammation can weaken or rupture the fibrous cap of the plaque, which can then lead to a blood clot called a thrombus. If this clot blocks the artery, it can cause a heart attack called a myocardial infarction, according to the report.

Karhunen outlined that earlier doctors believed coronary artery disease was caused mainly by oxidized LDL cholesterol. However, the new study suggests that hidden bacterial infections could also play a major role.

"Our study demonstrated the presence of genetic material, DNA, from several oral bacteria inside atherosclerotic plaques," she added.

To study the role of bacteria in heart attacks, the researchers examined tissue samples from two groups of people. The samples were taken from patients who had died of sudden cardiac death and from atherosclerosis patients who were having surgery to clear their peripheral and carotid arteries.

By analysing these samples, the study could depict hidden bacteria in plaques, which could play a key role in sudden heart attacks.

“The findings were validated by developing an antibody targeted at the discovered bacteria, which unexpectedly revealed biofilm structures in arterial tissue. Bacteria released from the biofilm were observed in cases of myocardial infarction. The body's immune system had responded to these bacteria, triggering inflammation which ruptured the cholesterol-laden plaque,” the report mentioned.

The researchers say that even though this study found a new possible cause of heart attacks, traditional factors such as high cholesterol, smoking and high blood pressure are still very important. These traditional risk factors continue to increase the chances of heart disease and must be managed and controlled, the study suggests.