OBJECTIVETo compare the value of intravascular ultrasound (IVUS) and assess the value of quantitative coronary angiography (QCA) and 64 multi-detector computed tomography (MDCT) on unstable anginas (UAP) risk stratification.

METHODA total of 61 UAP patients (low risk: 17, middle risk: 33 and high risk: 11) were recruited, 71 vessels were examined by MDCT, QCA and IVUS. Plaque characteristics (soft, fibrous, calcified and mixed plaques) and plaque burden at minimum area (< or = 50%, 51% - 74% and > or = 75%) were detected, calculated and analyzed. Results derived from various detection methods were compared.

RESULTSPlaque burden detection by QCA was comparable to IVUS results for low and middle risk UAP (r = 0.768 and r = 0.721, respectively; all P < 0.01) but not for high risk UAP (67% + or - 14% vs.75% + or - 16%, P < 0.01) due to significant positive vessel remodeling (remodeling index = 1.21 + or - 0.31). The high negative predict value of MDCT for stenosed coronary vessels (87.8% - 96.3%)was valuable for exclusion of coronary heart disease but MDCT was not able to identify fibrous cap (kappa = 0.235) and lipid core (kappa = 0.245). Extent of remodeling index, external elastic membrane area, minimum lumen area, plaque burden, plaque rupture and thrombosis increased in proportion to increasing risks of UAP patients.

CONCLUSIONSQCA is a suitable tool for assessing UAP patients with low and middle vessel stenosis but underestimated the stenosis degree in UAP patients with high vessel stenosis. MDCT is valuable for exclusion vessel disease but not useful for identifying soft and fibrous plaque. Soft plaque with positive remodeling index and minimum lumen area < 4 mm(2) derived from IVUS could correctly identify UAP patients with high degree of vessel stenosis.