In-Stent Neointimal Proliferation Correlates With the Amount of Residual Plaque Burden Outside the Stent

Abstract

Background —The aim of this study was to evaluate the relationship between residual plaque burden after coronary stent implantation and the development of late in-stent neointimal proliferation. Methods and Results —Between January 1996 and May 1997, 50 patients underwent intravascular ultrasound (IVUS) interrogation at 6±1.2 months after coronary stent implantation in native coronary arteries. IVUS images were acquired with a motorized pullback, and cross-sectional measurements were performed within the stents at 1-mm intervals. The following measurements were obtained: (1) lumen area (LA), (2) stent area (SA), (3) area delimited by the external elastic membrane (EEMA), (4) percent neointimal area calculated as (SA−LA/SA)×100, and (5) percent residual plaque area calculated as (EEMA−SA)/EEMA×100. Volume measurements within the stented segments were calculated by applying Simpson’s rule. In the pooled data analysis of 876 cross sections, linear regression showed a significant positive correlation between percent residual plaque area and percent neointimal area ( r =0.50, y = 45.03+0.29 x , P <0.01). There was significant incremental increase in mean percent neointimal area for stepwise increase in percent residual plaque area. Mean percent neointimal area was 16.3±10.3% for lesions with a percent residual plaque area of <50% and 27.7±11% for lesions with a percent residual plaque area of ≥50% ( P <0.001). The volumetric analysis showed that the percent residual plaque volume was significantly greater in restenotic lesions compared with nonrestenotic lesions (58.7±4.3% versus 51.4±5.7%, respectively; P <0.01). Conclusions —Late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation, supporting the hypothesis that plaque removal before stent implantation may reduce restenosis.