Background: The relationship between blood lipid profile and coronary plaque tissue characteristics, and differences in the tissue characteristics between acute coronary syndrome (ACS) and chronic coronary artery disease (CCAD) are unclear. The purpose of the present study was to compare the plaque tissue characteristics in patients with ACS and CCAD and to examine the relationship between the tissue characteristics and blood lipid profile.
Methods and results: Integrated backscatter intravascular ultrasound (IVUS) and conventional IVUS were performed in patients with ACS (n=24) and CCAD (n=68) at the time of coronary intervention. Percent tissue volume and cross-section area of lipid pool, fibrous tissue, dense fibrous and calcification were defined in target lesions. The lipid pool area (LPA) in the ACS patients was significantly higher than in the CCAD patients (LPA, 7.0+/-3.4 vs 5.1+/-3.2 mm(2), P=0.01). In the CCAD group, LPA/non-LPA ratio tended to be higher in the ACS than in the CCAD patients (1.4+/-0.9 vs 1.1+/-0.8; P=0.08), and LDL/HDL ratio was an independent predictor for LPA/non-LPA ratio (P=0.002). In addition, LDL/HDL ratio was a useful index for the prediction of a high LPA/non-LPA ratio (area under the receiver operating characteristic curve = 0.79).
Conclusions: Elevated LDL/HDL ratio may be a positive predictor for coronary lipid-rich plaque and plaque vulnerability in patients with CCAD.