A novel quantitative method for evaluating diffuse in-stent narrowing at follow-up angiography

A new quantitative parameter, diffuse index (DI), was proposed to evaluate objectively whether in-stent restenosis is diffuse or focal in nature. A to tal of 343 patients (346 lesions) with Wiktor-GX, AVE MS-II, or JOMED stent s were evaluated at follow-up angiography. According to the OCA-CMS definit ion, lesion length is derived from the 100% reference diameter function (RD F). By moving the RDF downward, the lesion length, LL(x), at each percentag e x of the RDF can be calculated. We have defined the DI by the ratio of th is calculated length LL(x) and the total stent length, SL, in other words, DI = [LL(x)/SL]. The percentage plaque area (% PA) was calculated by dividi ng the plaque area by the sum of the plaque area and luminal area within th e stent. An excellent correlation was found between the DI at 88% RDF and t he % PA in all three stents (r > 0.88). The individual correlation curves w ere nearly identical, independent of the type of stent. Furthermore, based on the overall data, the combination of a DI > 0.8 and % PA > 30% correlate d with a high incidence of subsequent major adverse cardiac events (13/25 = 52%). From these data, it can be concluded that the diffuse index is a new objective quantitative parameter to describe whether in-stent restenosis i s of focal or diffuse nature. (C) 2001 Wiley-Liss, Inc.