Longitudinal plaque redistribution during stent expansion

The purpose of this study was to clarify the 3-dimensional behavior of plaq ue during coronary stent expansion. Serial intravascular ultrasound (IVUS) studies, preintervention, and poststenting were evaluated in 32 patients tr eated with a single-balloon expandable tubular stent. External elastic memb rane (EEM), lumen, stent, and plaque + media cross-sectional area were meas ured at I-mm intervals through the entire stent as well as proximal and dis tal reference segments 5 mm from the stent edge. Volumetric calculations we re based on Simpson's rule. Overall, the plaque + media volume through the entire lesion did not change during stent expansion (218 +/- 51 vs 217 +/- 47 mm(3), p = 0.69). However, EEM and lumen volume increased significantly Inc. (EEM volume, 391 +/- 84 vs 448 +/- 87 mm(3) [p <0.0001]; lumen volume, 173 +/- 52 vs 231 +/- 54 mm(3) [p <0.0001]). The change in lumen volume co rrelated strongly with the change in EEM volume (r = 0.85, p <0.0001), but poorly with the change in plaque + media volume (r = 0.37, p = 0.03). Plaqu e + media volume decreased in the midstent zone (59 +/- 14 vs 53 +/- 11 mm( 3), p = 0.0005), and increased in the distal stent zone (40 +/- 11 vs 44 +/ - 9 mm(3), p 0.003), but did not change in either the proximal stent zone o r reference segments. The mechanism of stent expansion is a combination of vessel stretch and plaque redistribution, translating disease accumulation from the midstent zone to the distal stent zone. (C) 2000 by Excerpta Medic a,Inc.