Journal of Invasive Cardiology

FULL TITLE: Comparison of Acute Vessel Wall Injury After Self-Expanding Stent and Conventional Balloon-Expandable Stent Implantation: A Study with Optical Coherence Tomography

ABSTRACT: Background. The acute impact in vivo from a self-expanding stent on the vessel wall has not been sufficiently evaluated. Objectives. We sought to compare acute in vivo injury on the vessel wall and the clinical impact between a self-expanding coronary stent and conventional balloon-expandable stents immediately after stent implantation. Methods. We included 40 patients (45 vessels) with stable or unstable angina who were assigned to either the self-expanding stent (vProtect® Luminal Shield) group (n = 9; Group 1) or the conventional balloon-expandable stent group (n = 36; Group 2). Optical coherence tomography (OCT) was performed after stent deployment, as were qualitative and quantitative assessments of tissue prolapse, intrastent dissection, edge dissection and incomplete stent apposition. Results. Tissue prolapse was visible in all vessels in both groups. The corrected tissue prolapse area by stent length was larger in Group 2 than in Group 1 (0.06 ± 0.06 vs. 0.02 ± 0.01 mm²; p < 0.001). Intrastent dissection was more frequently seen in Group 2 (33/36 vs. 4/9 vessels; p = 0.004) and the mean length of the dissection flap was greater in Group 2 than in Group 1 (277.6 ± 110.0 vs. 76.9 ± 103.7 µm; p < 0.001). Although edge dissection was not detected in Group 1, it was visible in 19/36 vessels (52.8%) in Group 2. The frequency of incomplete stent apposition was not significantly different between Group 2 and Group 1 (23/36 vs. 7/9 vessels, p = 0.7), but the mean depth of incomplete stent apposition was greater in Group 2 than in Group 1 (268.2 ± 72.1 vs. 178.2 ± 156.7 µm, p = 0.03). Conclusions. A self-expanding stent was associated with less intrastent dissection and edge dissection than conventional balloon-expandable stents with OCT.

J INVASIVE CARDIOL 2010;22:435–439

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Although balloon-expandable stenting techniques with high pressure have proved to be useful for optimal stent implantation to reduce the risks of restenosis and subacute thrombosis, this stent deployment strategy may also increase the risk of creating vessel damage in the stented segment or at its edges.¹ As a stent is expanded with high pressure, immediate injury occurs deep in the vessel wall within the stented segment as well as in the unscaffolded persistent margins.² Importantly, several stent trials have drawn our attention to the problem of accelerated lumen loss at stent margins, which accounts for up to one-third of target-vessel revascularization (TVR) in patients treated with balloon-expandable stents.^3–5 On the other hand, a self-expanding stent allows deployment at lower pressures, resulting in less intimal trauma. Late loss was significantly smaller at the persistent margins in the self-expanding stent than it was in the balloon-expandable stent.²

Optical coherence tomography (OCT) is a high-resolution technique that allows very detailed assessment of the relationship between the stent and the vessel wall.