Circulating levels of micro- and nanoplastics (MNPs) were associated with structural plaque vulnerability in acute coronary syndrome (ACS), using optical coherence tomography (OCT), according to research published May 20 in JACC: Cardiovascular Imaging.

In the single-center observational study, conducted in Beijing, China, between July and December 2023, study investigators Yunxiao Yang, MD, PhD, et al., used pyrolysis-gas chromatography-mass spectrometry to analyze blood samples from 80 patients with ACS (57 years; 19% women; 10% with STEMI) and found circulating MNPs in all – with the most common polymer types being polyethylene (52%) and polyvinyl chloride (32%). Median total MNP concentration was 108.41 μg/g blood.

Results as observed through OCT found plaque rupture (PR) in 39 patients (49%), thin-cap fibroatheroma (TCFA) in 31 patients (39%) and macrophage infiltration (MØI) at the site of culprit plaques in 45 patients (56%).

Patients with PR, TFCA and MØI all had significantly higher total MNP levels than those without (PR, median 128.87 vs. 88.60 μg/g blood; TFCA, median 136.65 vs. 86.78 μg/g blood; MØI, median 134.04 vs. 78.09 μg/g blood; p<0.001 for all).

MNP levels were shown to have a moderate discriminative performance, with area under the ROC curve of 0.71 for PR, 0.74 for TCFA and 0.78 for MØI. Investigators identified 126.67 μg/g blood as the optimal threshold associated with PR (sensitivity, 56.4%; specificity, 75.6%).

"Despite effective [standard modifiable risk factor]-targeted therapies, a subset of patients develops ACS without traditional risk factors, suggesting the contribution of additional environmental or systemic exposures," write the study authors. "The detection of MNPs in all enrolled patients and their association with vulnerability phenotypes raise the possibility that chronic plastic exposure may be associated with alterations in plaque biology."