In vivO Study of assessmeNt for Efficacy and safetY of Zotarolimus-eluting Stent OVERexpansion With Optical Coherence Tomography (ONYSOVER Trial)

Single stent implantation (also called "provisional stenting") is currently the preferred technique for percutaneous coronary interventions on the majority of unprotected left main (LM) or non-LM bifurcations. During provisional stenting, proximal optimization technique (POT), proved to correct both the proximal main vessel (MV) malapposition and/or optimize the side branch (SB) ostium strut opening for proper wire re-crossing into the distal cell, might be crucial step and may warrant improved long-term clinical outcomes in the setting of major proximal and distal reference vessel size mismatch (like often in LM bifurcation or diffuse tapered long lesion).

Recently, second-generation drug-eluting stent (DES) implantation is recommended over BMS for PCI in patients with ischemic heart disease (IHD) due to superior efficacy and safety. However, percutaneous coronary intervention (PCI) with DES for lesion with the discrepancy of proximal and distal reference vessel size, such as LM or non-LM bifurcation lesion, diffuse tapered long lesion, and ectatic or aneurysmal coronary artery, is challenging due to stent optimization because expert consensus recommend that stent diameter is selected by distal reference diameter, which need stent overexpansion for POT.

OCT is a utility that can accurately measure reference vessel diameter and lesion length pre-PCI, which is useful for stent optimization by a suitable stent selection and pre- and post-interventional strategies. OCT also demonstrated higher sensitivity to detect stent malapposition, edge dissection, and tissue prolapsed than IVUS post-PCI. Thus, OCT-guided PCI can be helpful to optimize DES implantation in patients with dilated coronary arteries despite the potential limitation of depth penetration and attenuation images by thrombus.

Zotarolimus-eluting stent (Onyx family stent, Medtronic, Santa Rosa, CA, USA) was developed in response to the demand for stents with improved radiographic visibility. It has a novel thin strut composite wire stent platform that is covered with the same zotarolimus-eluting durable polymer coating as its predecessors. The metallic stent platform consists of a composite wire made from a dense platinum-iridium core, which makes the struts radiopaque, and an outer layer of cobalt-chromium alloy. The dense core also allows for reduced strut thickness, which might be associated with a decreased risk of stent thrombosis.

Onyx family stent has been labeled for maximum stent inner diameter by easy crowns platform (2.00-2.5 mm, 6.5 Crowns; 2.75-3.0 mm, 8.5 crowns; 3.5-4.0 mm, 9.5 crowns; 4.5-5.0 mm; 10.5 crowns). However, safety and efficacy of DES overexpansion is still concerned as safety of efficacy of there are limited data regarding Onyx family stent overexpansion in vivo.