Arterial remodeling after balloon angioplasty or stenting in an atherosclerotic experimental model.

BACKGROUND: Recent studies have indicated that coronary restenosis after balloon angioplasty is the sum of geometric remodeling and neointimal formation. A proportional relationship between acute gain and late lumen loss has been observed in clinical trials. The aims of this study were to evaluate (1) the contribution of geometric remodeling and neointimal formation to the proportional gain-loss relationship after PTA or stenting and (2) the relationship between geometric remodeling and neointimal formation. METHODS AND
RESULTS: In atherosclerotic iliac arteries of 29 Yucatan micropigs, PTA or stenting was performed, with serial intravascular ultrasound (IVUS) and quantitative angiography before and after intervention and at 2 or 42 days of follow-up, followed by histomorphometrical analysis. For PTA at 42 days, late lumen loss by IVUS correlated strongly with geometric remodeling, expressed as late media-bounded area (MBA) loss (R2=.843, P<.001, n=20), and correlated weakly with intimal hyperplasia area (R2=.214, P=.02). For stented arteries, however, late lumen loss correlated moderately with intimal hyperplasia (R2=.367, P=.01, n=18) and only weakly with geometric remodeling (R2=.195, P=.04). Late lumen loss and late MBA loss of reference segments were observed at 42 days, especially in PTA arteries. Intimal hyperplasia and geometric remodeling were not correlated.
CONCLUSIONS: In this experimental model, the proportional relationship between acute gain and late lumen loss is mainly due to the proportional relationship between acute gain and geometric remodeling for PTA and between acute gain and intimal hyperplasia for stents. Finally, neointimal formation and remodeling seem to be unrelated processes.