# Associations of non-traditional lipid parameters with high-risk plaques characterized by optical coherence tomography in acute myocardial infarction culprit lesions

## TL;DR

This study finds that non-traditional lipid markers like ApoB/A1 and non-HDL-C are linked to high-risk heart plaques in patients with acute myocardial infarction, as seen through OCT imaging.

## Contribution

The study introduces the combined use of non-traditional lipid parameters to better identify high-risk plaques in AMI patients.

## Key findings

- ApoB/A1 and non-HDL-C were independently and linearly associated with high-risk plaques.
- Combining these markers improved model discrimination and clinical prediction of plaque risk.
- High-risk plaques were more common in males and STEMI patients with elevated lipid markers.

## Abstract

The objective of this research was to investigate the association between non-traditional lipid parameters and optical coherence tomography (OCT)-characterized high-risk plaques in patients with acute myocardial infarction (AMI).

This retrospective study included 249 first-episode AMI patients admitted to the First Affiliated Hospital of Lanzhou University between January 2022 and December 2024. All patients underwent OCT-guided assessment of culprit lesions before revascularization. High-risk plaques were defined by more than two of the following features: lipid arc ≥90 °, fibrous cap thickness <65 μm, or plaque rupture/thrombus. Lesions with fewer than two of these criteria were classified as non-high-risk plaques. Clinical and laboratory data were collected, and a comprehensive lipid profile was calculated, including traditional indicators [e.g., non-HDL cholesterol (non-HDL-C)] and non-traditional ratios [e.g., apolipoprotein B/A1 ratio (ApoB/A1)]. Spearman correlation was used to assess relationships between lipid parameters and high-risk plaques. After excluding collinear variables, logistic regression, restricted cubic spline (RCS), and subgroup analyses were performed. Model discrimination and clinical value were evaluated using receiver operating characteristic (ROC) curves, the DeLong test, integrated discrimination improvement (IDI), net reclassification index (NRI), and decision curve analysis (DCA).

Among 249 AMI patients, 137 (55.0%) exhibited OCT-characterized high-risk plaques. These patients were more often male (89.8%) and presented with STEMI (84.7%). They had elevated levels of myoglobin, LDL-C, non-HDL-C, ApoB, ApoB/A1, remnant lipoprotein cholesterol (RLP-C), non-HDL-C/HDL-C ratio (NHHR), and TC/HDL-C (all P < 0.05). OCT features included thinner fibrous caps, smaller lumen areas, larger lipid arcs, and higher incidences of rupture, erosion, thrombus, macrophage infiltration, cholesterol crystals, and calcification (all P < 0.05). Both ApoB/A1 (OR = 3.688, 95% CI: 1.211–11.230) and non-HDL-C (OR = 3.023, 95% CI: 1.238–7.378) were independently and linearly associated with high-risk plaques. No significant interactions were observed across clinical subgroups (all P for interaction > 0.05). The combined model incorporating the two markers achieved the highest discriminative performance (AUC = 0.696) and significantly improved the baseline model (DeLong test P < 0.05), with additional gains confirmed by IDI, NRI, and DCA (all P < 0.05).

Both the non-traditional ApoB/A1 ratio and the traditional lipid marker non-HDL-C were independently and linearly associated with OCT-characterized high-risk plaques in AMI. Their combined assessment enhanced the identification of high-risk plaques morphology.