Plaque distribution and vascular remodeling of ruptured and nonruptured coronary plaques in the same vessel: An intravascular ultrasound study in vivo

OBJECTIVES This study was designed to identify potential differences betwee n the intravascular ultrasound (IVUS) characteristics of spontaneously rupt ured and nonruptured coronary plaques. BACKGROUND The identification of vulnerable plaques in vivo may allow targe ted prevention of acute coronary events and more effective evaluation of no vel therapeutic approaches. METHODS Intravascular ultrasound was used to identify 29 ruptured plaques i n arteries containing another nonruptured plaque in an adjacent segment. In travascular ultrasound characteristics of these plaques were compared with plaques of computer-matched controls without evidence of plaque rupture. Pl aque distribution was assessed by measuring the eccentricity of lumen locat ion (inside the total vessel). Lumen cross-sectional area narrowing was cal culated as [1 - (target/reference lumen area)] x 100%. A remodeling index w as calculated as lesion/reference arterial area (>1.05 = compensatory enlar gement, <0.95 = shrinkage). RESULTS Among the three groups of plaques, there was no significant differe nce in quantitative angiographic parameters, IVUS reference dimensions and IVUS lumen cross-sectional area narrowing. There was a difference in plaque distribution; lumen location by IVUS was significantly more eccentric in r uptured than in nonruptured (p = 0.002) and control plaques (p < 0.0001). T he are of disease-free vessel wall was larger in ruptured than in control p laques (p < 0.0001). The remodeling pattern of ruptured and nonruptured pla ques differed significantly fr om that of the control plaques (p = 0.0001 a nd 0.003); compensatory enlargement was found in 66%, 48%, and 17%, whereas shrinkage was found in 7%, 10% and 48%, respectively. CONCLUSIONS Intravascular ultrasound assessment of plaque distribution and vascular remodeling may help to classify plaques with the highest probabili ty of spontaneous rupture. (J Am Coll Cardiol 2001;37:1864-70) (C) 2001 by the American College of Cardiology.