Elevated serum uric acid level was reportedly associated with greater coronary lipid plaque. Xanthine oxidoreductase (XOR) is a rate-limiting enzyme in purine metabolism and believed to play an important role in coronary atherosclerosis. However, the relation of XOR to coronary lipid plaque and its mechanism are unclear. Patients with stable coronary artery disease undergoing elective percutaneous coronary intervention under near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) guidance were prospectively enrolled. They were divided into three groups according to serum XOR activities: low, normal, and high. Coronary lipid core plaques in non-target vessels were evaluated by NIRS-IVUS with lipid core burden index (LCBI) and a maximum LCBI in 4 mm (maxLCBI4mm). Systemic endothelial function and inflammation were assessed with reactive hyperemia index (RHI) and high-sensitivity C-reactive protein, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio. Of 68 patients, 26, 31, and 11 were classified as low, normal, and high XOR activity groups. LCBI (474.4 ± 171.6 vs. 347.4 ± 181.6 vs. 294.0 ± 155.9, p = 0.04) and maxLCBI4mm (102.1 ± 56.5 vs. 65.6 ± 48.5 vs. 55.6 ± 37.8, p = 0.04) were significantly higher in high XOR group than in normal and low XOR groups. Although RHI was significantly correlated with body mass index, diabetes, current smoking, and high-density lipoprotein cholesterol, no relation was found between XOR activity and RHI. There were also no relations between XOR activity and C-reactive protein, neutrophil-to-lymphocyte ratio, or platelet-to-lymphocyte ratio. In conclusion, elevated XOR activity was associated with greater coronary lipid core plaque in patients with stable coronary artery disease, without significant relations to systemic endothelial function and inflammation.
Keywords: Endothelial function; Inflammation; Uric acid; Xanthine oxidoreductase.