NOVEL-APPROACH TO THE ANALYSIS OF RESTENOSIS AFTER THE USE OF 3 NEW CORONARY DEVICES

Restenosis after coronary intervention has remained a vexing problem despite the introduction of nearly 24 newer coronary interventional devices. To more clearly evaluate the potential impact of three such new devices on restenosis, coronary lumen diameters were measured before, immediately after and at 6 months after intervention, and restenosis was analyzed using continuous geometric techniques. Lumen diameters were measured before and immediately after intervention in 223 coronary vessels treated with one of three new devices: a single Palmaz-Schatz stent (n = 87), directional atherectomy (n = 125) and laser balloon angioplasty (n = 11); 184 (83%) of the patients underwent follow-up angiography 6 months after treatment. The immediate increase in lumen diameter produced by the intervention (acute gain) and the subsequent reduction in lumen diameter between the time of intervention to 6 month follow-up study (late loss) were examined. For each of the three interventions, the restenosis rate at follow-up study was analyzed using a traditional dichotomous definition (greater-than-or-equal-to 50% diameter stenosis), as well as a novel graphic technique. Although the apparent restenosis rates differed significantly among the three interventions (19% for stents, 31% for atherectomy and 50% for laser balloon angioplasty; p = 0.02), late loss among the three interventions was equivalent (average 1 mm; p = 0.91). There were, however, marked differences in the acute gain achieved by the three interventions: 2.6 mm for stents, 2.2 mm for atherectomy and 2 mm for laser balloon angioplasty; p < 0.001). It was these differences in acute gain rather than late loss that explained the observed differences in restenosis rate. By using a continuous rather than a dichotomous view of restenosis and resolving long-term device results in the components of acute gain and late loss, analysis of this patient set provides unique insights into the potential role of these new devices in reducing restenosis. The absolute magnitude of late loss in lumen diameter (reflecting local intimal hyperplasia) was equivalent among the three devices and was greater than the late loss previously reported for conventional balloon angioplasty. Therefore, the ability of a newer device to reduce restenosis may be related more to its ability to provide the greatest acute gain in lumen diameter, rather than the ability to reduce subsequent intimal hyperplasia.