Combined Assessment of Elevated Plasma Lipoprotein-Associated Phospholipase A2 and Plaque Enhancement Improved Accuracy in the Risk of Acute Ischemic Stroke in Patients with Intracranial Artery Stenosis

A Non-Linear Role of Hyperlipidemia on Progression of Intracranial Atherosclerotic Plaques and Acute Downstream Ischemic Events

AIM

Intracranial atherosclerotic stenosis (ICAS) is the leading cause of ischemic stroke worldwide. Hyperlipidemia is a major contributor to atherosclerosis. However, the effect of hyperlipidemia on the evolution of intracranial atherosclerotic plaques and downstream ischemic episodes remains unclear. In this study, we aimed to assess the radiological features of ICAS plaques and to explore the relationship between hyperlipidemia and plaque progression.

METHODS

We included people with ICAS (≥50% stenosis) undergoing high-resolution magnetic resonance imaging. The culprit plaque was defined as the sole, or in case of multiple stenosis, the narrowest plaque on the intracranial artery responsible for acute ischemic stroke. Demographic, clinical data, plaque features on MRI, and lipid parameters were compared between culprit and non-culprit plaques. Plaque enhancement was graded as Grade 0, 1 and 2 by comparing to the adjacent normal vessel wall and pituitary funnel after contrast enhancement on T1-weighted sequences.

RESULTS

162 patients were included (mean age 57.7±12.1 years, male 61.6%), 110 of whom were identified as culprit plaque with an ipsilateral acute stroke. High-grade enhancement was the most prominent MRI feature of the culpable plaque (Grade-2: OR 6.539, 95%CI 1.706-23.707, p=0.006). LDL cholesterol was significantly associated with overall acute ischemic stroke caused by culprit plaque. After stratification by enhancement grading LDL was independently associated with ischemic events in Grade-1 enhancement plaques (OR 6.778, 95%CI 2.122-21.649, p=0.001). In patients with Grade-2 enhancement plaques, however, LDL was not associated with ischemic event; in contrast, Neutrophil/Lymphocyte ratio was independently associated with ischemic events caused by Grade-2 enhancement plaques (OR 2.188, 95%CI 1.209-3.961, p=0.010).

CONCLUSIONS

LDL was related with ischemia events in intermediate stage of intracranial atherosclerotic plaque progression, an excellent period for intensive lipid-lowering treatment. In advanced stage, inflammatory agents maybe the main contributor to ischemic events.

Elevated Lipoprotein-Associated Phospholipase A2 Is Associated With Intracranial Atherosclerosis

Background

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory factor in the pathogenesis of atherosclerotic plaque and is associated with an increased risk of ischemic stroke. Whether Lp-PLA2 is associated with stenosis subtypes in acute ischemic stroke (AIS) has not been investigated.

Methods

A total of 126 eligible AIS patients were divided into four groups: (1) no cerebral artery stenosis (NCS); (2) intracranial artery stenosis (ICAS); (3) extracranial artery stenosis (ECAS); and (4) combined intracranial and extracranial artery stenosis (IECS). Associations between serum Lp-PLA2 levels and the stenosis subtypes were assessed.

Results

The ICAS group had a lower frequency of dyslipidemia as compared to the NCS group and the IECS group (35.3% vs. 70% vs. 71.8%, respectively, p = 0.001) and was more likely to be symptomatic than the ECAS group (76.5% vs. 43.8%, respectively, p = 0.014). Lp-PLA2 levels in the ICAS group were 112.2 ± 66.8 μg/L which are, higher than those in the NCS, ECAS, and IECS groups (81.7 ± 38.5, 106.1 ± 57.8, 89.3 ± 52.2 μg/L, respectively, p = 0.025). In the third and fourth quartiles of Lp-PLA2 levels, stenosis had occurred more frequently in the ICAS group than in the other three groups (third Q: 50.0% vs. 3.1% vs. 28.1% vs. 18.8%, p = 0.002; fourth Q: 48.4% vs. 16.1% vs. 25.8% vs. 9.7%, p = 0.014). Lp-PLA2 levels were higher in patients with more or severe stenosis in the ICAS group.

Conclusions

Elevated Lp-PLA2 levels were differentially associated with increased risk in AIS patients with ICAS compared to those with ECAS or no stenosis. Lp-PLA2 may be a promising biomarker and potential therapeutic target for ICAS.