Longitudinal Stent Elongation Due to Inappropriate Post-Dilatation　― Insight From a Bench Test ―

A 48-year-old man underwent very long stent (VLS) implantation for chronic total occlusion (CTO) in the mid-right coronary artery. Ostial stent implantation was displaced due to longitudinal stent elongation (LSE) caused by post-dilatation (Figure A–F). A VLS is useful for reducing the number of stents and stent overlaps when treating diffuse lesions; however, LSE post-dilatation is sometimes observed, primarily caused by malapposed struts due to differences in vessel diameter between proximal and distal lesions. Inappropriate post-dilatation can lead to LSE, a critical issue, especially in ostial lesions requiring proximal stent edge determination.

Figure.

(A) Initial and (E) final coronary angiography. (B,C) Stent implantation. (D) Dilatation of the stent-delivery balloon. (F) Longitudinal stent elongation. (G) Bifurcation silicon model showing stent implantation. Comparison of post-dilatation Technique (I) using a stent-delivery balloon and Techniques (II–IV) using 4.5/8-mm non-compliant balloons. Numbers 1–4 indicate the sequence order.

The proximal optimization technique (POT), effective in bifurcation lesions, may resolve this concern; however, its application in post-VLS implantation and the best post-dilatation procedure have yet to be identified.¹ We investigated the best post-dilatation procedure to prevent LSE using an in vitro bifurcation silicon model (Figure G). We compared 4 different methods after implantation of a 3.5/38-mm stent (Ultimaster Nagomi; Terumo, Japan): (I) post-dilatation using a stent-delivery balloon (rated burst 16 atm pressure); and POT using a 4.5/8-mm non-compliant balloon (nominal 12 atm pressure) with (II) a distal to proximal sequence, (III) a proximal to distal sequence, and (IV) the following order: proximal, distal, and middle parts (Figure G; Supplementary Movie). Stent length in the pre-/post-balloon angioplasties was measured using optical frequency domain imaging (FastView; Terumo). The stent lengths dimensions pre- vs. post-dilatation were as follows: (I) 39.2 vs. 42.1 mm; (II) 39.3 vs. 41.9 mm, (III) 38.7 vs. 38.7 mm, and (IV) 38.6 vs. 38.6 mm. Thus, POT, including angioplasty for the proximal stent edge, in Techniques III and IV is useful in preventing LSE. Despite limitations (the absence of bending and CTO factors), the results of our bench test suggest that post-dilatation with particular attention to the proximal stent edge may prevent LSE.

Sources of Funding

This study did not receive any specific funding.

Disclosures

None declared.

Supplementary Files

Supplementary Movie. Comparison of procedures (I)–(IV).

Please find supplementary file(s);

https://doi.org/10.1253/circrep.CR-23-0026

Reference

• 1.   Burzotta F, Lassen JF, Louvard Y, Lefèvre T, Banning AP, Daremont O, et al. European Bifurcation Club white paper on stenting techniques for patients with bifurcated coronary artery lesions. Catheter Cardiovasc Interv 2020; 96: 1067–1079.