Heart attack patients have higher levels of microplastics in their blood, says study

“Our findings not only support the well-established link between fine particulate air pollution (PM2.5) and acute cardiovascular events, but for the first time connect PM2.5 exposure and smoking with the presence of micro- and nanoplastics across the spectrum of coronary artery disease,” said Dr Pasquale Paolisso, clinical cardiologist at Sant ’Andrea University Hospital in Rome and the study’s first author.

Another risk factor for heart disease

Dr K Srinath Reddy, Chancellor of the Public Health Foundation of India Institute of Public Health Sciences (deemed to be a university) and former head of the Department of Cardiology at AIIMS, New Delhi, said the research adds another environmental risk factor to the growing list of contributors to heart disease. “This study suggests that microplastics may be one more factor causing long-term damage to coronary arteries and triggering acute heart attacks,” Dr Reddy told The Indian Express. “The researchers also found a less strong, but still important, association between blood levels of microplastics and chronic coronary artery disease.”

Chronic coronary artery disease is a long-term condition in which fatty deposits gradually build up inside the coronary arteries, reducing blood flow to the heart. Over time, this can cause chest pain, breathlessness and increase the risk of a heart attack. A heart attack, by contrast, occurs suddenly when one of these arteries becomes completely blocked, cutting off blood supply to part of the heart muscle.

Dr Reddy also pointed to the particularly strong association between smoking and higher blood levels of microplastics. “These may come directly from cigarette filters or be absorbed more easily because smoking damages the lungs’ natural protective barriers,” he explained. “This could be another hidden factor contributing to heart attacks, even in people who otherwise appear healthy.”

What are microplastics?

Micro- and nanoplastics are extremely small plastic particles that have become widespread environmental pollutants. According to the United Nations Environment Programme (UNEP), microplastics range in size from one nanometre to five millimetres. A nanometre is many thousands of times smaller than the width of a human hair, while five millimetres is about the width of a wedding band.

These particles are now found almost everywhere — in the air, drinking water, soil and food. UNEP estimates that around 2.7 million tonnes of microplastics entered the environment in 2020, and that figure is expected to double by 2040 if current trends continue. People are exposed mainly by inhaling polluted air or ingesting contaminated food and water, and increasing evidence suggests that these particles can accumulate in human tissues.

The researchers note that while people are routinely exposed to microplastics, little has been known about how much accumulates in the bloodstream during different stages of heart disease.

What the study found

The multicentre study enrolled 61 patients undergoing coronary angiography, an imaging procedure used to examine the heart’s arteries. The participants were divided into three groups. The first included 19 patients with ST-elevation myocardial infarction (STEMI), the most severe type of heart attack caused by complete blockage of a coronary artery, who underwent emergency angioplasty (primary percutaneous coronary intervention or PCI). The second group included 20 patients with chronic coronary syndrome, a stable form of coronary artery disease caused by narrowed arteries, who underwent planned angioplasty. The third group consisted of 22 people whose coronary angiograms showed normal arteries and who served as the control group.

Researchers collected blood samples both from the coronary arteries supplying the heart and from elsewhere in the body. They also recorded participants’ smoking history and estimated their exposure to PM2.5 air pollution on the day of testing as well as over the previous two years.

Micro- and nanoplastics were detected in 84.2 per cent of patients with acute heart attacks, compared with 40 per cent of patients with chronic coronary artery disease and 31.8 per cent of those with normal coronary arteries. The most commonly detected plastic was polyethylene, which is widely used in packaging materials and everyday consumer products.

Patients with acute heart attacks also had significantly higher concentrations of microplastics in both coronary and peripheral blood than the other two groups. Higher exposure to PM2.5 and a history of smoking were independently associated with greater microplastic levels in the bloodstream.

Why it matters

The researchers say the findings add to growing evidence that micro- and nanoplastics are biologically active pollutants rather than simply inert contaminants. Laboratory and animal studies have suggested that these particles may trigger inflammation, damage blood vessels, accelerate the build-up of fatty plaques inside arteries and make existing plaques more unstable. These mechanisms could increase the risk of cardiovascular events, although this has yet to be conclusively demonstrated in humans.

The study also offers a possible explanation for how air pollution and microplastics may act together. Because both are primarily inhaled, PM2.5 particles may act as carriers, transporting microplastics deep into the lungs. Together, the two pollutants may damage the lung’s protective barrier, allowing microplastics to enter the bloodstream and potentially contribute to inflammation throughout the body.

The findings underscore the need to view pollution as a cardiovascular health issue, not just an environmental one. Reducing exposure to air pollution, tobacco smoke and plastic pollution should now become part of broader population-level strategies to prevent heart disease, rather than focusing only on individual risk factors such as cholesterol, diabetes and high blood pressure.