Intracoronary ultrasound: A necessary tool for stent implantation? Arguments in favour

Intracoronary ultrasound (ICUS), as opposed to angiography, provides high r esolution, tomographic images of the coronary vessel and lumen. Because of its superior diagnostic sensitivity ICUS is indicated in the evaluation of suboptimal results and complications following stent implantation. Only a f ew years ago the use of stents was limited by a high incidence of subacute thrombosis. ICUS demonstrated that the deployment technique used at that ti me was inadequate and that stent expansion could be improved by the routine use of high pressure inflation, leading to a simplification in the anticoa gulation regimen and a decrease in the subacute thrombosis rate in elective procedures to less than or equal to 1%. However, the routine use of high b alloon pressures does not assure an adequate expansion of the stent. Only a bout one third of the stents deployed under angiographic guidance are optim ally expanded, with intra-stent luminal dimensions similar to the adjacent, reference, luminal sizes. Significantly, these underdeployed stents can be recognized by ICUS and a large proportion adequately expanded. It should b e emphasized that the best predictors of stent restenosis are two ICUS para meters, the postprocedural luminal dimensions and the %cross sectional narr owing, and not the angiographic parameters. Likewise, two of the lowest res tenosis rates ever reported (12.8% and 7.3%) have occurred in two studies ( WEST-S and MUSIC) in which stent deployment was guided by ICUS. Two trials (AVID and OPTICUS) have been specifically designed to test the hypothesis t hat routine use of ICUS to guide stent implantation could diminish the rest enosis rate, but their final results are not yet available. The CRUISE stud y was designed to evaluate the impact of routine ICUS not on angiographic r estenosis but on the clinical need of revascularization. In this trial, the larger luminal dimensions of-the stents implanted under ICUS guidance tran slated into a 40% reduction in the 6 month revascularization rate (14.8 % v s. 8.9%, p < 0.05). Although the final answer is still pending, the availab le information suggests that the routine use of ICUS might translate into a direct clinical benefit, something remarkable for a diagnostic tool. In an y case, the most effective way of using ICUS would probably be identifying those lesions that most benefit from the technique and avoiding its nse in lesions with, a priori, excellent results.