PREDICTORS OF LUMINAL NARROWING BY NEOINTIMA AFTER ANGIOPLASTY IN ATHEROSCLEROTIC RABBITS

Objective: The present study was designed to identify the predictors o f cross-sectional area narrowing by neointima (%CSAN-N) after balloon angioplasty (BA) in the cholesterol fed rabbit model. Methods: Angiogr aphic, histomorphometric, and immunohistochemical data were analyzed f rom 91 femoral arteries of New Zealand white rabbits. Focal atheroscle rosis was induced by air desiccation of the endothelium followed by a 2% cholesterol diet for 28 days. The rabbits received heparin (150 U/k g) at the time of BA (2.5 mm; three, 60-second, 10-atm inflations). Ar teries were perfusion-fixed and excised 7 (n = 16), 14 (n = 11), 21 (n = 9), or 28 (n = 20) days after BA. Non-angioplastied arteries were d e-endothelialized (cholesterol-fed [n = 12] or normal diet [n = 8]), n on-injured but cholesterol-fed (n = 7), or normal (n = 8). Results: Un ivariate regression across all groups showed that the absolute area of the lumen by histomorphometry (LA) correlated significantly with the area bounded by the external elastic lamina (EEL) (vessel size), but n o correlation was found with the absolute area of neointima or media, the percentage disruption of the internal elastic lamina (IEL), or the percentage of neointima and media occupied by foam cells. However, %C SAN-N correlated significantly with the area bounded by the EEL, signi ficantly with the absolute neointimal area, and negatively with the ab solute LA(p < 0.0001). Significant correlations were also found betwee n %CSAN-N and the % IEL disrupted, the area of neointima and media occ upied by RAM-11 + foam cells, and the loss of alpha-actin positivity i n the media (p < 0.0001). Conclusions: These studies show that neointi mal formation contributes significantly to luminal narrowing 1 month a fter angioplasty in this model, that the degree of vascular injury and the extent of foam cell accumulation in the neointima and media are s ignificant independent predictors of neointimal formation, and that th e area of the neointima, and the percent narrowing by neointima, are i mportant predictors of remodeling itself (EEL area). These predictors were not identifiable when the analysis was focused on the determinant s of absolute luminal area alone. (C) 1997 Elsevier Science B.V.