IMPACT OF INTRAVASCULAR ULTRASOUND GUIDANCE IN STENT DEPLOYMENT ON 6-MONTH RESTENOSIS RATE - A MULTICENTER, RANDOMIZED STUDY COMPARING 2 STRATEGIES - WITH AND WITHOUT INTRAVASCULAR ULTRASOUND GUIDANCE

Objectives. We aimed to investigate the impact of intravascular ultras ound (IVUS)-guided stent implantation on the 6-month restenosis rate, which has not yet been fully established in randomized trials. Backgro und. The 6-month angiographic restenosis rate was compared in patients with symptomatic ischemic heart disease who were randomly allocated t o angioplasty and stent deployment, with versus without IVUS guidance. Methods. After successful stent implantation, patients were randomize d into two groups: Group A had no further dilation, and Group B had ad ditional balloon dilation until achievement of IVUS criterion for sten t expansion. The study group consisted of 164 patients, assuming a 50% reduction of the restenosis rate in Group B (15% vs. 30%) (alpha = 10 %, beta = 20%). Results. We enrolled 155 patients. Overdilation was ca rried out in 31 (39%) of 79 Group B patients, with the IVUS criterion being achieved in 63 (80%) of 79. No significant difference was observ ed in the minimal luminal diameter (MLD), but the stent lumen cross-se ctional area (CSA) was significantly larger in Group B (mean +/- SD) ( 7.16 +/- 2.48 vs. 7.95 +/- 2.21 mm(2), p = 0.04). At 6 months, there w as no significant difference in the restenosis rate, (28.8% [21 of 73] in Group A vs. 22.5% [16 of 71] in Group B, p = 0.25), but according to the observed difference in the restenosis rate, the power of the st udy was only 40%. The difference in MLD was also nonsignificant (1.60 +/- 0.65 mm in Group A vs. 1.70 +/- 0.64 mm in Group B, p = 0.20), whe reas the lumen CSA was 20% larger in the IVUS-guided group (4.47 +/- 2 .59 vs. 5.36 +/- 2.81 mm2, p = 0.03). Lumen CSA was the only predictor of restenosis by multivariate logistic regression analysis. Conclusio ns. A nonsignificant 6.3% absolute reduction in the restenosis rate an d a nonsignificant difference in MLD were observed in this study. None theless, we still cannot rule out a beneficial effect of IVUS guidance , although this may have gone undetected owing to a lack of statistica l power. A significant increase was observed in immediate and 6-month lumen size, as detected by IVUS, indicating that ultrasound guidance i n stent deployment may be beneficial. (C) 1998 by the American College of Cardiology.