IMPACT OF PLAQUE MORPHOLOGY AND COMPOSITION ON THE MECHANISMS OF LUMEN ENLARGEMENT USING INTRACORONARY ULTRASOUND AND QUANTITATIVE ANGIOGRAPHY AFTER BALLOON ANGIOPLASTY

Limited information is provided by angiography on on plague morphology and composition before balloon angioplasty: Identification of plaques associated with reduced lumen gain or a high complication rate may pr ovide the rationale for using alternative revascularization devices. W e studied 60 patients with quantitative angiography and intracoronary ultrasound (ICUS) before and after balloon dilation. Angiography was u sed to measure transient wall stretch and elastic recoil. ICUS was use d to investigate the mechanisms of lumen enlargement among different p laque compositions and in the presence of a disease-free wall (minimal thickness less than or equal to 0.6 mm). Compared with ultrasound, an giography underestimated the presence of vessel calcification (13% vs 78%), lumen eccentricity (35% vs 62%), and wall dissection (32% vs 57% ). ICUS measurements showed that balloon angioplasty increased lumen a rea from 1.82 +/- 0.51 to 4.81 +/- 1.43 mm(2). Lumen enlargement was t he result of the combined effect of an increase in the total cross-sec tional area of the vessel (wall stretching, 43%) and of a reduction in the area occupied by the plaque (plaque compression or redistribution , 57%). Vessels with a disease-free wall had smaller lumen gain than o ther types of vessels (2.13 +/- 1.26 vs 3.59 +/- 1.51 mm(2), respectiv ely, p <0.01). Wall stretching was the most important mechanism of lum en enlargement in vessels with a disease-free wall (79% vs 37% in the other vessels). Angiography revealed a direct correlation between temp orary stretch and elastic recoil that was responsible for 26% of the l oss of the potential lumen gain. Thus, lumen enlargement after balloon angioplasty is the combined result of wall stretch and plaque compres sion or redistribution. ICUS indicates that vessels with a remnant are of disease-free wall are dilated mainly by wall stretching compared w ith other types of vessels and are associated with a smaller lumen gai n.