Microbes linked to heart attacks finds study

By Dr. Ananya Mandal, MDSep 1 2019

A study revealed at the ESC Congress 2019 held in Paris last weekend reveals that abnormal microbe population in the body may lead to impairment of the stable coronary plaques and lead them to be dislodged leading to a heart attack. The abstract titled, “A different microbial signature in plaque and gut of patients presenting with ACS: a possible role for coronary instability” was presented on the 31st of August 2019.

Image Credit: William Perugini / Shutterstock

The study revealed along with the World Congress of Cardiology explains that the health of the gut bacteria is determinant of inflammatory courses in the body. The team of researchers explained that the gut microbes of those with a heart attack have been found to be different from those who have stable angina. They added that heart attacks and heart disease in general has more than one contributing factor including obesity, diabetes, smoking and alcohol intake, age and concurrent medications being some of them. These factors affect the immunity, system metabolism and microbiome of the gut is an additional influencing factor on heart health.

For this study the team included 30 patients who were diagnosed with acute coronary syndrome and compared them with ten patients who were being treated for stable angina. Both groups had been found to have developed coronary plaques in their coronary arteries. These plaques are clumps of platelets and inflammatory cells that often get dislodged from their site of origin and clog up the coronary arteries leading to ischemic heart disease or angina and heart attacks. For all the 40 enrolled patients samples of faeces were collected and the gut microbial picture was obtained. Angioplasty is a procedure where a probe is inserted into the coronary arteries to break the plaques and dilate the arteries by placing a balloon like stent. From these angioplasty balloons, for each of the patients, bacterial samples present in the plaques were gathered.

The team of researchers then went on to compare the microbes present on both the faeces and the coronary plaques and found that the bacterial population in the two were different. Bacteria in the faeces had a diverse variety of population with a majority of Bacteroidetes and Firmicutes. On the other hand the bacteria on the coronary plaques were mainly those that triggered inflammatory responses and belonged to the species Proteobacteria and Actinobacteria. According to the first author First author Eugenia Pisano, of the Catholic University of the Sacred Heart, Rome, Italy, who also presented the research work at the conference, “This suggests a selective retention of pro-inflammatory bacteria in atherosclerotic plaques, which could provoke an inflammatory response and plaque rupture.” She added that the results also revealed that the coronary plaques of those who were diagnosed with the heart attack or acute coronary syndrome had more of Firmicutes, Fusobacteria and Actinobacteria. Those who had stable angina had more of Bacteroidetes and Proteobacteria in their coronary plaques. Pisano said, “We found a different make-up of the gut microbiome in acute and stable patients. The varying chemicals emitted by these bacteria might affect plaque destabilisation and consequent heart attack. Studies are needed to examine whether these metabolites do influence plaque instability.”

The team explained that there have been several studies in the past connecting altered gut microbiota with heart attacks but no study has shown the connection of gut microbiota and inflammation that could lead to plaque instability. Pisano added that this study is the first that reveals the bacterial population differences in the plaques and antibiotics against Chlamydia Pneumoniae have shown no benefit in preventing cardiac events in these patients. She said, “While this is a small study, the results are important because they regenerate the notion that, at least in a subset of patients, infectious triggers might play a direct role in plaque destabilisation. Further research will tell us if antibiotics can prevent cardiovascular events in certain patients.”

Pisano said in conclusion, “Microbiota in the gut and coronary plaque could have a pathogenetic function in the process of plaque destabilisation and might become a potential therapeutic target.”

Related study

Another recent study also found a connection between gut bacteria and atherosclerosis. Atherosclerosis is the basis of coronary artery disease that leads to heart attacks and strokes.

For this study the team examined the genetic make-up of the bacteria present in the faeces of the participating population. They noted that patients with atherosclerosis had a greater count of a bacterial group called Collinsella. These bacteria are responsible for making peptidoglycan which can trigger inflammatory processes in the body.