Morphological effects on in-stent restenosis assessed by intravascular ultrasound imaging

The purpose of this study was to evaluate the rupture and dissection of the vessel wall immediately after balloon dilatation by intravascular ultrasou nd (IVUS) imaging and to predict restenosis in patients who underwent subse quent coronary stent implantation. Stent implantation improves the long-term results of coronary angioplasty b y reducing lesion elastic recoil and arterial remodeling. However, several studies have suggested that neointimal hyperplasia is the cause of in-stent restenosis. We recruited 60 patients in whom IVUS studies were performed immediately af ter successful balloon dilatation and just before stent implantation. We co mpared IVUS parameters with 6-month follow-up quantitative coronary angiogr aphy. This was performed in 51 lesions of 51 patients (85%). Qualitative an alysis included assessment of plaque composition, plaque eccentricity, plaq ue fracture and the presence of dissection. In addition, minimal luminal di ameter, percent diameter stenosis, percent area stenosis and plaque burden were quantitatively analyzed. Two morphological patterns after balloon dilatation were classified by IVUS . Type I was defined as absence or partial tear of the plaque without discl osure of the media to lumen (22 lesions). Type II was defined as a split in the plaque or dissection of the vessel wall with disclosure of the media t o the lumen (29 lesions). At 6 months follow-up, angiographic restenosis oc curred in 17 of the 51 lesions (33%). Restenosis was significantly (p < 0.0 5) more likely to occur in type II (13/29: 45% incidence) than in type I (4 /22: 18% incidence). The assessment of plaque morphology immediately after balloon dilatation an d before stent implantation provides important therapeutic and prognostic i mplications.