701-2 The Final % Cross-sectional Narrowing (Residual Plaque Burden) is the Strongest Intravascular Ultrasound Predictor of Angiographic Restenosis

We analyzed clinical, intravascular ultrasound (IVUS), and angiographic predictors of restenosis (follow-up quantitative angiographic % diameter stenosis>50) in 384 lesions (133 LAD, 42 LCX, 121 RCA, 88 SVG) in 322 pts (259 males, ages 59±11 yrs). Transcatheter devices were 56 PTCA; 126 directional, 70 rotational, and 3 extraction atherectomy; 56 stents; and 73 excimer laser angioplasty. Univariate IVUS parameters tested included reference site and target lesion pre- and post-intervention external elastic membrane (EEM), lumen, and plaque areas; % cross-sectional narrowing (%CSN = plaque/EEM area); and lesion morphology (eccentricity, plaque composition, calcium, and dissections). Using multivariate analyses, the most consistent predictor of follow-up angiographic findings was the IVUS final % CSN. Using logistic regression analysis, the final %CSN predicted restenosis (odds ration 2.09; 95% confidence interval = 1.50-2.92, P<0.001, Figure); using linear regression analysis, %CSN predicted both the follow-up angiographic % diameter stenosis (r=0.371, P<0.001) and minimum lumen diameter (r=0.396, P<0.001). In addition, various referencesegment measurements (eg., angiographic lumen diameter or IVUS EEM or lumen area or %CSN) were included in some of the multivariable models; but no one measure of reference vessel size or disease consistently predicted follow-up results. Importantly, the following did not predict restenosis: (1) lesion morphology and (2) mechanisms of lumen enlargement (increase in EEM or decrease in plaque).We ConcludeThe final IVUS %CSN was a more powerful predictor of restenosis than clinical or angiographic variables. Eitheran increase in EEM (vessel expansion) ora decrease in plaque (tissue removal) will reduce the final % CSN. Thus, it is the magnitude, not the mechanism, of successful transcatheter therapy that is related to freedom from restenosis