Size of emptied plaque cavity following spontaneous rupture is related to coronary dimensions, not to the degree of lumen narrowing: A study with intravascular ultrasound in vivo

Objective - To identify any potential relations between the size of an emptied plaque cavity and the remodelling pattern, plaque or vessel dimensions, lumen narrowing, and other ultrasonic lesion characteristics. Design - Intravascular ultrasound was used to examine prospectively 51 ruptured ulcerated coronary plaques. Cross sectional area measurements comprised lumen, vessel, plaque, and emptied plaque cavity. Lumen narrowing was calculated as 1 - (lesion lumen area/reference lumen area) x 100%. A remodelling index was calculated as lesion vessel area/reference vessel area, and plaques were divided into those with values > 1.05 (group A) and ≤ 1.05 (group B). Results - Of the total of 51 plaques, 36 (71%) were assigned to group A and 15 (29%) to group B. In neither group was there a significant difference in reference dimensions and lumen narrowing. However, lesion vessel (mean (SD): 22.6 (8.1) mm² υ 17.5 (4.3) mm²; p = 0.006) and plaque areas (15.8 (6.2) mm² υ 12.8 (3.2) mm²; p = 0.03) were greater in group A than in group B. The cavity inside the plaque was larger in group A than in group B (2.8 (1.6) mm² υ 1.8 (0.9) mm²; p = 0.007) and showed a positive linear relation with lesion and reference vessel size (r = 0.58 and 0.56, respectively; p < 0.001), but not with lumen narrowing. Conclusions - The size of the emptied cavity inside ruptured plaques is on average larger in lesions with adaptive vascular remodelling, and shows a linear relation with lesion plaque and vessel size and with the reference dimensions, but not with the degree of lumen narrowing.