Online three-dimensional OFDI-guided versus angiography-guided PCI in bifurcation lesions: design and rationale of the randomised OPTIMUM trial

Abstract

Aims: The feasibility of offline optical coherence tomography (OCT) guidance in bifurcation (with either two-dimensional or three-dimensional images) and its potential benefits have been demonstrated in retrospective studies; however, these have not yet been investigated prospectively. The aim of this trial is to determine the superiority of online three-dimensional optical frequency domain imaging (3D-OFDI)-guided stenting to angiography-guided percutaneous coronary intervention (PCI) in terms of incomplete stent apposition (ISA) at the bifurcation segment.

Methods and results: The OPTIMUM trial is a randomised, superiority, multicentre clinical trial. The primary endpoint of this trial is the post-procedural percentage of malapposed struts assessed by OFDI in the main branch bifurcation region after final kissing balloon dilatation (FKBD). A total of 106 patients will be randomly allocated to either 3D-OFDI guidance or angiography guidance PCI. Bifurcation lesions will be treated with a provisional single-stent strategy using the Ultimaster sirolimus-eluting stent. Patients randomised to the 3D-OFDI guidance arm will undergo OFDI assessment in the main branch (MV) after rewiring into the jailed side branch following stent implantation, while in the angiography guidance arm re-crossing of a wire into the side branch will be performed using conventional fluoroscopic/angiographic guidance. In patients in the 3D-OFDI guidance arm, if the position of the wire is not located in the optimal cell, further attempts to redirect the wire to the optimal cell will be performed, with subsequent OFDI acquisitions to confirm the re-crossing position. The proximal optimisation technique and FKBD are mandatory in this trial. The study will provide a 90% power to show superiority of 3D-OFDI guidance PCI compared with angiography-guided PCI.

Conclusions: The OPTIMUM trial will be the first prospective, randomised trial to evaluate the efficacy and safety of online 3D-OFDI-guided PCI in bifurcation lesions. ClinicalTrials.gov Identifier: NCT02972489.

Figure 1

The difference in stent configuration between distal and proximal cell rewiring with kissing balloon inflation. In a phantom model, a stent was implanted in a main vessel. In panel A the wire was re-crossed through a distal cell, while in panel B the wire was re-crossed through a proximal cell. This was confirmed by 3D-OCT (C, D, E, & F). After kissing balloon inflation, in the distal cell rewiring case, the ostium of the side branch was widely open without malapposed struts (G & K), while, in the proximal cell rewiring case, the malapposed struts (yellow arrows) were observed in front of the side branch as assessed by OCT (H & L). The computational flow simulation showed a high shear rate by the malapposed struts in front of the side branch (I, J). 3D-OCT confirmed the malapposed struts in front of the side branch after proximal cell rewiring with kissing balloon inflation, while, after distal cell rewiring with kissing balloon, the ostium of the side branch was widely open. Reproduced with permission from Onuma et al.

Figure 2

Angio-guided PCI is limited in recognising a re-crossing position. Angio-guided PCI is limited in recognising a re-crossing position whether it is a proximal or distal cell, while OFDI-guided PCI can confirm the re-crossing position. Hence, angio-guided PCI would lead to either an optimal or a suboptimal result, while OFDI-guided PCI would lead to an optimal result.

Figure 3

OFDI core lab analysis. The post-procedural percentage of malapposed struts (primary endpoint) will be assessed in the main branch bifurcation region.

Figure 4

Study flow chart.

Figure 5

Optimal re-crossing point. Configuration 1: when the most distal stent ring is in contact with the rim of the carina, a second distal compartment is considered as the optimal cell. Configuration 2 & 3: in the presence of multiple second distal compartments, a larger compartment should be selected.

Figure 6

Metallic carina created after proximal cell rewiring with kissing balloon inflation. A) 3D-OCT images show that the re-crossing wire was located in the proximal cell (suboptimal case). The jailed stent struts are pushed to the distal side of the vessel due to the dilatation of the balloon at the orifice of the side branch, causing overlapping of struts (yellow circle) and also a metallic neocarina (red circle) (B). Reproduced with permission from the OCT Atlas (second edition).

Figure 7

A case example of 3D-OCT-guided PCI. A) The 3D-OCT image indicates that the guidewire re-crossed through the proximal cell at the first attempt at re-crossing the wire. B) The 3D-OCT image shows that the guidewire re-crossed the optimal cell (i.e., the most distal cell) at the second attempt at re-crossing the wire. C) The ostium of the left circumflex was well opened and no ISA was observed. Reproduced with permission from Okamura et al.

Figure 8

Incomplete stent apposition and the configuration of overhanging struts in front of the ostium. In configuration 1 (without a link in front of the ostium) with distal rewiring (A), no ISA was observed in front of the side branch ostium (A’). In configuration 3, even though distal rewiring was achieved (B), malapposed struts were detected (B’). Reproduced with permission from the OCT Atlas (second edition).

Figure 9

Terumo OFDI system and Ultimaster coronary stent. Left panel: pictures of imaging catheter. Middle panel: pictures of imaging system. Right panel: Ultimaster stent after kissing balloon inflation in a bifurcation model (upper) and potential cell opening in 3.5 mm device (lower). Reproduced and adapted with permission from the OCT Atlas (second edition).