Angiographic and Intravascular Ultrasound Predictors of In-Stent Restenosis
ABSTRACT & COMMENTARY
Synopsis: Intravascular ultrasound guidance may optimize stent deployment and ultimately decrease in-stent restenosis rates.
Source: Kasaoka S, et al. J Am Coll Cardiol 1998; 32:1630-1635.
Intracoronary stents have been shown to reduce restenosis compared with balloon angioplasty. However, in-stent restenosis (ISR) continues to be an important clinical problem. The ability to predict restenosis and subsequently alter procedural decisionmaking would provide invaluable information. Thus, Kasaoka and associates sought to determine predictors of ISR from a high-volume, single-center practice. Between April 1993 and March 1997, 1706 consecutive patients with 2343 lesions were treated with a variety of intracoronary stents, predominantly Palmaz-Shatz (46%). Angiographic follow-up was requested in all patients within six months. Those patients with angiographic follow-up comprised the patient study group. Clinical, angiographic, and intravascular ultrasound (IVUS) variables were analyzed to determine predictors of ISR. All stents were deployed with standard high-pressure balloon inflations to achieve angiographically optimal results. IVUS was performed in 79% of patients. ISR was angiographically documented in 24% of the patients.
The restenosis group had a higher incidence of hyperlipidemia, diabetes, and previous bypass surgery. Additionally, they had more complex lesion morphology with more type C lesions and dissections and more frequently required multiple stents and a longer total stent length. Angiographic predictors of ISR included a longer lesion length, a smaller final minimal luminal diameter (MLD), and a higher percent diameter stenosis. IVUS indicators of a higher restenosis recurrence include a smaller final stent lumen cross-sectional area. In those patients who had IVUS guidance to optimize stent deployment, additional balloon inflations were performed and more stents placed. These lesions had a significantly larger final MLD, a smaller final diameter stenosis, and a greater acute gain. More important, the lesions with IVUS guidance had a statistically significant lower restenosis rate (24% vs 29%; P = 0.03). Kasaoka et al conclude that using IVUS guidance to achieve the optimal stent lumen and minimizing total stent length may reduce ISR.
Comment by Michael H. Crawford, MD
Intracoronary stents have become common in therapy for coronary artery disease. Advances in stent technology have facilitated ever more challenging stent procedures to be performed. With this has come the problem of ISR, which poses a significant challenge as we have yet to discover a good solution. In various series looking at ISR, "re-restenosis" occurs anywhere from 20-80% of the time. Thus, the onus is on us to identify methods of optimizing stent deployment and to predict which stent results may pose a greater risk of restenosis. This information could provide valuable guidance in angioplasty technique and modality selection.
The total stent length and the number of stents used were significant variables by univariate analysis, and total stent length was the strongest predictor of restenosis in the multivariate analysis. These results suggest that an optimal result should be achieved using a minimum amount of metal and perhaps tolerating moderate downstream disease and small, non-flow-limiting dissections. This also raises the issue of focal stenting in a diffusely diseased vessel. Further study of these issues is warranted. However, it has become clear that, if possible, the use of long or multiple stents should be kept to a minimum.
Those patients who had stents placed with IVUS guidance had a significantly decreased (20%) incidence of restenosis. In patients who have been identified to be at high risk for restenosis—diabetics, hyperlipidemics—post-CABG, the use of IVUS may markedly improve the stent result and thereby decrease restenosis. Judicious use of IVUS may have a positive effect on immediate results and long-term clinical outcome, which would more than compensate for the additional cost and time involved. Finally, patient selection for stenting must be revisited. Perhaps other modalities besides stenting should be first considered and applied knowing this may provide the eventual use of a stent in the event of restenosis.
This is an exciting paper that addresses the ongoing dilemma of restenosis. The ability to predict those patients at risk for restenosis may provide the avenue by which to alter and enhance our current techniques.
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