齋藤 佑一

Elevated serum uric acid (SUA) level is known to be a prognostic factor in patients with acute coronary syndrome (ACS). However, the pathogenesis of the relation between SUA level and coronary plaque characteristics has not been fully evaluated. The aim of this study was to investigate the relation between SUA level and plaque composition of nonculprit lesions in patients with ACS. A total of 81 patients with ACS who underwent intravascular ultrasound (IVUS)-guided percutaneous coronary intervention were included. They were classified into 3 groups according to tertiles of SUA level. Using integrated backscatter (IB)-IVUS system, tissue components were classified into 4 categories: calcium deposits, dense fibrosis, fibrosis, and lipid. Tertiles of SUA level were as follows: low tertile <5.0 mg/dl; intermediate tertile 5.0 to 6.4 mg/dl; and high tertile >6.4 mg/dl. There was a trend toward greater vessel volume in the high tertile group than in the low and intermediate tertile groups (19.4 ± 3.7 vs 17.4 ± 4.4 vs 16.7 ± 4.1 mm(3)/mm, p = 0.05). There was no significant difference in lumen volume between the 3 groups. Plaque volume was significantly greater in the high than in the low tertile group (8.6 ± 2.4 vs 6.7 ± 2.2 mm(3)/mm, p = 0.01). IB-IVUS analysis demonstrated greater lipid (59.1 ± 9.1% vs 49.7 ± 10.9% vs 51.1 ± 9.3%, p = 0.001) and less fibrous components (36.8 ± 7.8% vs 44.3 ± 7.8% vs 43.2 ± 6.7%, p <0.001) in the high than in the low and intermediate tertile groups. Multivariate analysis showed high SUA as an independent predictor of increasing lipid volume. In conclusion, elevated SUA level is associated with greater lipid content of coronary plaque in patients with ACS than in patients with normal levels.