Impact of lesion complexity on the capacity of a trial to detect differences in stent performance: results from the ISAR-STEREO trial.

BACKGROUND: A number of stent-versus-stent trials have not been able to disclose differences in stent performance. It has been hypothesized that the selection of patient subsets with simple lesion morphologies may have masked differences among the stent designs under testing. The randomized Intracoronary Stenting and Angiographic Results Strut Thickness Effect on Restenosis Outcome (ISAR-STEREO) trial has shown that a reduced stent strut thickness is associated with a reduced risk for restenosis. The rationale of this study was to investigate the role of lesion complexity on the capacity of a stent-versus-stent trial to distinguish between superior and inferior stents. METHODS: In the ISAR-STEREO trial, 651 patients were randomly assigned to receive either a thin-strut (n = 326) or a thick-strut stent (n = 325) with a comparable stent design. Restenosis, defined as a > or =50% diameter stenosis at follow-up angiography, was analyzed according to the lesion complexity, which was assessed with the use of the American College of Cardiology/American Heart Association classification system. RESULTS: The restenosis rate did not differ between stent designs in patients with noncomplex lesions (type A or B(1); restenosis rate: 16.7% vs 16.7%, P = 1.0 for thin-strut vs thick-strut stents). In patients with complex lesions (type B2 or C), there was a significant reduction in restenosis in the thin-strut stent group (restenosis rate: 14.5% vs 29.0%; P <.01 for thin-strut vs thick-strut stents). CONCLUSIONS: The results of this study suggest that the potential to detect differences in the risk for restenosis in stent-versus-stent trials is strongly dependent on the inclusion of patients with complex lesions. These findings may be relevant when planning new stent-versus-stent trials.

Intracoronary stenting and angiographic results: strut thickness effect on restenosis outcome (ISAR-STEREO-2) trial.

OBJECTIVES: We tested the hypothesis that thinner-strut stents are associated with a reduced rate of restenosis when comparing two stents with different design. BACKGROUND: We have previously shown that, for two stents with similar design, the risk for restenosis is dependent on the strut thickness. It is unknown whether strut thickness preserves its relevance as a determinant of restenosis even in the presence of different stent designs. METHODS: A total of 611 patients with symptomatic coronary artery disease were randomly assigned to receive either the thin-strut ACS RX Multilink stent (Guidant, Advanced Cardiovascular Systems, Santa Clara, California) (strut thickness 50 microm, interconnected ring design; n = 309) or the thick-strut BX Velocity stent (Cordis Corp., Miami, Florida) (strut thickness 140 microm, closed cell design; n = 302). The primary end point was angiographic restenosis (> or =50% diameter stenosis at follow-up angiography). Secondary end points were the incidence of target-vessel revascularization (TVR) and the combined rate of death and myocardial infarction (MI) at one year. RESULTS: The incidence of angiographic restenosis was 17.9% in the thin-strut group and 31.4% in the thick-strut group, relative risk, 0.57 (95% confidence interval, 0.39 to 0.84), p < 0.001. A TVR due to restenosis was required in 12.3% of the thin-strut group and 21.9% of the thick-strut group, relative risk, 0.56 (95% confidence interval, 0.38 to 0.84), p = 0.002. No significant difference was observed in the combined incidence of death and MI at one year. CONCLUSIONS: When two stents with different design are compared, the stent with thinner struts elicits less angiographic and clinical restenosis than the thicker-strut stent.