Abstract Body (Do not enter title and authors here): Background:
Malondialdehyde-modified low-density lipoprotein (MDA-LDL) is believed to play a critical role in plaque destabilization. However, there is limited evidence regarding the clinical characteristics and histopathological features of patients with elevated MDA-LDL levels in the context of acute coronary syndrome (ACS).

OBJECTIVE:
We aimed to investigate tissue characteristics of the culprit lesion assessed by IVUS and tissue obtained in patients with ACS who underwent thrombus aspiration during emergency coronary catheterization and compared with MDA-LDL levels.

Methods:
We enrolled 62 consecutive patients with ACS who underwent emergency catheterization were classified into 2 groups based on low MDA-LDL levels (<100 U/L) and high MDA-LDL levels (≥100 U/L). We analyzed the association of the culprit lesion phenotype by IVUS (lipid lesion, fibrous lesion, calcified lesion) and thrombus aspiration tissue with MDA-LDL levels.

Results:
The patients with ACS were divided into two groups: 48 patients with low MDA-LDL levels and 14 patients with high MDA-LDL levels. The high MDA group was younger than the low MDA group (62.1±14.1 vs. 72.6±11.1 years, P=0.031). In addition, T-cho levels (248 ± 54.7mg/dL vs 185.8 ± 36.5mg/dL, P<0.01), LDL-C (157.6 ± 42.6mg/dL vs 109±31.4, P<0.01) and TG (197 ± 107.9mg/dL vs 108 ± 64.2mg/dL, P<0.01), HbA1c (7.36 ± 1.85% vs 6.26 ± 0.82%, P=0.02) were significantly higher in the high MDA group than the low MDA group. Furthermore, IVUS analysis of culprit lesion revealed the high MDA-LDL group had more lipid lesions (0.85 ± 0.36 vs 0.53 ± 0.50, P=0.038) and less fibrous lesions (0.07 ± 0.26 vs 0.40 ± 0.50, P=0.038) than the low MDA-LDL group. In addition, the thrombus aspirated tissues showed that T-cell infiltration in culprit lesion was more common in high MDA-LDL group with lipid lesions.

Conclusions:
Patients with ACS with elevated MDA-LDL frequently had dyslipidemia and diabetes mellitus, and the culprit lesions were unstable plaques with a high lipid lesion with T-cell infiltration. These findings suggest that the aggressive lipid-lowering therapy and DM control are important for plaque stabilization in ACS patients with elevated MDA-LDL levels.