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.

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 ≥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.

The restenosis rate did not differ between stent designs in patients with noncomplex lesions (type A or B₁; 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).

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.