Cardiology Online

16th World Congress on Heart Disease

controversies meeting



Stent Strut Thickness Affects Restenosis Rate
March 23, 2002

ATLANTA, Georgia (ACC) -- Innovations in stenting were highlighted during Sunday’s (March 17, 2002) Late-Breaking Clinical Trials session. In the ISAR-STEREO-2 trial in Germany, use of a thin-strutted stent was associated with a 43 percent reduction in the restenosis rate at six months compared with a thick-stented strut. And researchers in the TRENDS study report that direct stenting without pre-dilatation is both feasible and safe.

“Device characteristics of coronary stents appear to have a significant impact on restenosis development and long-term outcome,” said Dr. Helmut Schuhlen, of the German Heart Center, Munich, who described the ISAR-STEREO-2 (Intracoronary Stenting and Angiographic Results-Strut Thickness Effect on Restenosis Outcome) trial.

In the trial, 611 PTCA patients were randomized to the first-generation Multilink stent with 50-micrometer struts, or to the BX Velocity stent that is similar in design but has 140-micrometer struts.

Median stented length for the group of 309 patients receiving the Multilink was 22.0 mm and 20.7 for the 302 patients receiving the BX Velocity.

At six months, the rate of angiographic stenosis of 50 percent or greater was 17.9 percent for the thin strut compared with 31.4 percent for the thick strut, a 43 percent reduction, Dr. Schuhlen said. Median lumen diameter at six months was 1.96 mm with the thin-strut stent versus 1.70 mm with the thicker-strut model, a striking difference between the two, he said.

Survival free of myocardial infarction was approximately the same, 95.1 percent at one year for the thin strut and 93.7 percent for the thick strut.

Procedural success was also approximately the same, 99.4 percent for thin stents and 99.0 percent for thick stents. But device success was different: 87.1 percent for the thin-strut Multilink versus 99.0 percent for the BX Velocity, an outcome that Dr. Schuhlen attributed to the fact that the Multilink is a first-generation device, while the BX Velocity is a later-generation design.

“This trial demonstrates that there may be significant differences in restenosis based on stent design,” said session co-moderator William W. O’Neill, MD, Royal Oak, MI. “In the past, all of us concluded that lesion characteristics, implantation technique, and other nuances impacted most. But stent thickness may also impact enormously.”

Dr. O’Neill said because they will be comparing stents of different strut thickness, future trials of drug-eluting stents should take this information into account.

Direct Stenting Feasible
Stenting can be done with or without balloon predilatation and each approach has its advantages and disadvantages. But early results from the TRENDS (Tetra Randomized EuropeaN Direct Stenting) study show that the rate of major adverse cardiac events is approximately the same for both techniques.

“The strategy of direct stenting is contentious and in Europe there is a wide variety of opinions as to whether this is the best approach,” said Dr. Keith D. Dawkins, Wessex Cardiac Unit, Southamptom, U.K.

That debate may now be answered by the TRENDS study. The direct-stenting strategy failed in 31 of 541 stents—that is, only 5.8 percent of stents deployed directly failed to reach the lesion and had to be crossed over to the predilatation arm.

There were two deaths at 30 days among the 501 patients randomized to direct stenting, he said, versus one death among the 499 predilatation-arm patients.

Dr. Hawkins noted that the two trial arms were well balanced and that both included large subsets of patients with complex lesions that reflected a real-life patient population. Approximately 97 percent of all patients had a history of angina.

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