Relation between vascular morphologic changes during stent implantation and the magnitude of in-stent neointimal hyperplasia

Intimal hyperplasia usually occurs after balloon overstretch injury or wire coil stimuli to coronary arteries. We examined whether the degree of vessel wall stretch during coronary stent placement could predict the amount of in-stent neointimal hyperplasia after a 6-month follow-up. Serial (preintervention, postballooning, poststent implantation, and a follow-up after 6 months) intravascular ultrasound (IVUS) was used to study 457 consecutive cross-sectional areas in 28 patients. IVUS imaging, using a motorized pullback system at 0.5 mm/s, allowed 1-mm axial increment measurements of the total vascular, stent, and lumen cross-sectional areas. The mean total vascular area changed from 10.89 ± 2.50 mm2 before to 11.27 ± 2.49 mm2 after ballooning, to 12.80 ± 2.59 mm2 after stenting, and to 12.58 ± 2.41 mm2 at follow-up (p <0.0001). The mean lumen area changed from 3.36 ± 1.95 mm2 before to 4.21 ± 1.65 mm2 after ballooning , to 5.16 ± 1.09 mm2 after stenting, and to 3.57 ± 1.23 mm2 at follow-up (p <0.0001). The mean stent area decreased from 5.25 ± 1.17 mm2 after stenting to 5.09 ± 0.90 mm2 at follow-up (p <0.0001). Stepwise logistic regression analysis showed that Δ total vascular area (after stent implantation–before intervention) was a strong predictor of the amount of intimal hyperplasia (r = 0.57, p <0.0001). Vascular overstretch caused by the stenting procedure promotes intimal hyperplasia in proportion to the degree of sectional vascular stretch.