ARTERIAL REMODELING AT THE REFERENCE SITE AFTER ANGIOPLASTY IN THE ATHEROSCLEROTIC RABBIT MODEL

Recent studies suggest that arterial remodeling Flays an important rol e in restenosis and that remodeling at the reference site may also occ ur. To assess the chronic effect of the reference site remodeling on a ngioplasty results, we evaluated reference site remodeling in an exper imental atherosclerotic restenosis model. Histological sections of ili ac stenoses and their associated proximal reference segments from 50 a therosclerotic rabbits killed 4 weeks after angioplasty were analyzed. Lumen area (ZA), external elastic lamina area (EEL), and intimal plus medial areas (I+M) were measured at the lesion ((L)) and reference (( R)) sites. Angiography was performed preangioplasty, immediately posta ngioplasty, and 4 wesks pontangioplasty. Restenosis was defined ar an angiographic loss/gain ratio of greater than 50% at follow-up angiogra phy. Twenty-three lesions were restenotic (R+) and 32 were not (R-). T here was no difference in reference site diameters (RD) between these two groups at the time of angioplasty. However, RDs were significantly smaller in the R+ group than in the R- group (1.24+/-0.18 versus 1.52 +/-0.28 mm, n=55, P<.01) at 4-week follow-up. Morphometric analysis al so showed a smaller LA((R)) in the R+ group (0.85+/-0.27 versus 1.06+/ -0.37 mm(2), n=55, P<.02), whereas there was no difference in I+M-(R) between the two groups. EEL(R) significantly correlated with EEL(L), L A((R)), and I+M-(R), in both groups combined (r=.53, n=55, P<.0001; r= .62, n=55, P<.0001; and r=.86, n=55, P<.0001, respectively). Remodelin g can favorably and unfavorably affect both the lesion and the referen ce sites and appears to occur in parallel and proportionately at both sites. These data suggest that angiographic measurement of late percen t stenosis using reference site diameters may lead to an underestimati on of the percent luminal narrowing in restenotic lesions because unfa vorable remodeling occurs in both the lesion and reference sites in re stenotic vessels.