Increased circulating levels of malondialdehyde-modified low-density lipoprotein in patients with coronary microvascular dysfunction

Abstract

Coronary microvascular dysfunction (CMD) is associated with angina symptoms and adverse clinical outcomes in patients without obstructive coronary artery disease (CAD). Malondialdehyde-modified low-density lipoprotein (MDA-LDL) is reportedly a marker of the initiation and acceleration of epicardial coronary atherosclerosis. However, its impact on CMD remains unclear. We aimed to investigate the relationship between CMD and MDA-LDL levels. This study included 95 patients who did not receive lipid-lowering medications and had no obstructive CAD. Obstructive CAD was defined as >50 % diameter reduction on coronary angiography or fractional flow reserve of ≤0.80. We retrospectively analyzed coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and MDA-LDL levels. CMD was defined as either CFR <2.0 or IMR ≥25. CMD was observed in 29 (31 %) patients. MDA-LDL levels were significantly higher in patients with CMD than in those without CMD (124.8 ± 37.6 vs. 95.3 ± 29.5 U/L; < 0.01). Univariable logistic regression analysis indicated a significant relationship between CMD and MDA-LDL levels (odds ratio (OR): 1.03; < 0.01). In the multivariable model, MDA-LDL levels were significantly associated with CMD (OR: 1.02; < 0.01). Regression analysis showed a significant correlation between MDA-LDL levels and CFR (r = -0.42, < 0.01) and IMR (r = 0.35, < 0.01). In the multiple regression analysis, MDA-LDL levels were independently associated with CFR (β = -0.30, < 0.01) and IMR (β = 0.26, = 0.02). MDA-LDL levels were associated with CMD in patients without obstructive CAD.