Tiny plastics in carotid plaque tied to elevated risk for heart attack, stroke, death
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Key takeaways:
- Patients who had microplastics or nanoplastics in their carotid plaque were more likely to die or have a heart attack or stroke than those who did not.
- The findings confirm prior in vitro and animal studies.
Among patients with asymptomatic carotid artery disease who had carotid endarterectomy, those whose atheromas contained microplastics and/or nanoplastics had worse outcomes than those whose atheromas did not, researchers reported.
Risk for heart attack, stroke or all-cause death at nearly 3 years was more than fourfold higher in patients with carotid atheromas containing microplastics and/or nanoplastics (MNPs) than in those with no evidence of MNPs, the researchers wrote in The New England Journal of Medicine.
“Recent studies performed in preclinical models have led to the suggestion of MNPs as a new risk factor for cardiovascular diseases,” Raffaele Marfella, MD, PhD, from the department of advanced medical and surgical sciences at the University of Campania “Luigi Vanvitelli,” Naples, Italy, and colleagues wrote. “However, the clinical relevance of these findings is unknown. Evidence is lacking to show that MNPs infiltrate vascular lesions in humans or to support an association between the burden of MNPs and cardiovascular disease. To explore whether MNPs are detectable within atherosclerotic plaque and whether the burden of MNPs is associated with cardiovascular disease, we assessed the presence of these substances in surgically excised carotid artery plaque by means of pyrolysis-gas chromatography-mass spectrometry, stable isotope analysis and electronic microscopy. We then determined whether the presence of MNPs was associated with a composite endpoint of myocardial infarction, stroke or death from any cause.”
The researchers enrolled 304 patients with asymptomatic carotid artery disease undergoing carotid endarterectomy, of whom 257 completed follow-up of a mean of 33.7 months.
Marfella and colleagues detected polyethylene in the atheromas of 58.4% of patients (mean level, 21.7 g/mg of plaque) and found that 12.1% of those patients also had measurable amounts of polyvinyl chloride in their atheromas (mean level, 5.2 g/mg of plaque). In those with MNPs, the mean age was 71 years and 77.3% were men. In those without MNPs, the mean age was 73 years and 73.8% were men.
Electron microscopy showed “visible, jagged-edged foreign particles” in plaque macrophages and scattered in external debris, and X-rays revealed that some of these particles also contained chlorine, the researchers wrote.
Compared with those who had no MNPs detected, patients who had MNPs detected were at more than fourfold risk for MI, stroke or death during follow-up (20% vs. 7.5%; HR = 4.53; 95% CI, 2-10.27; P < .001), according to the researchers.
“Our findings suggest that nanoplastics, rather than microplastics, might accumulate in sites of atherosclerosis,” the researchers wrote. “Indeed, the large majority of particles detected in the current study were also below the 200 nm threshold suggested for gut and other barriers and were visible in the extracellular space as scattered debris, which aligns with the notion that the absorption and distribution of MNPs increase as particle size decreases.”
Perspective
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Larry B. Goldstein, MD, FAAN, FANA, FAHA
This is an important initial study showing an association between MNPs and cardiovascular outcomes. The primary finding is that patients with evidence of MNPs within atherosclerotic carotid artery plaques in asymptomatic persons were at higher risk of subsequent CV events. As pointed out by the authors, this does not necessarily mean that the two are causally linked because of the possibility of other unmeasured factors that could differ between those with and without MNPs. Preclinical data, however, provide some evidence of vascular effects of MNPs.
At this point, it is unclear what we can do to prevent events related to MNPs. MNPs are fairly ubiquitous. Because there appeared to be a relationship between the amount of MNPs and vascular events, developing strategies to reduce exposure on a population level may need to be considered.
This study was limited to patients who were treated for asymptomatic carotid artery atherosclerotic disease. Extending the observation to other populations would further support the association.
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