The OCTOBER trial: OCT-guided or angiography-guided PCI in complex bifurcation lesions
Reported from ESC Congress 2023
Dejan Milasinovic provides his take on the final results of the OCTOBER trial which were presented by Lene Nyhus Andreasen during the ESC 2023 congress in Amsterdam.
OCTOBER study investigated the effect of OCT-guided PCI for true bifurcation lesions (18% left main) in 1201 patients (1:1 randomization) on the 2-year occurrence of a combined endpoint of cardiac death and myocardial infarction or revascularization related to the target lesion. Randomization was stratified according to anatomy (left main vs. non-left main) and stenting technique (single vs. two-stent, both with mandatory final kissing balloon inflation (KBI)). OCT guidance amounted to at least 3 OCT runs, to a) plan the procedure prior to stenting, b) check the wire position after rewiring, and c) assess the post-stenting result.
The combined primary endpoint occurred less frequently in patients treated with an OCT-guided PCI, compared to angiography guidance (10.1% vs. 14.1%, HR 0.70, 95%CI 0.50-0.98, p=0.035), with all individual components being numerically lower in the OCT arm.
In light of the positive trial results, questions of external validity, i.e. applicability for real-world practice, emerge. In this regard, two issues seem relevant:
- Does OCTOBER provide evidence in favour of routine OCT guidance in true bifurcations?
- Which specific OCT quality markers were the main drivers of success?
However, the study design seems to render a direct answer to both questions difficult.
Firstly, patients in the OCTOBER trial who underwent single stent implantation were routinely treated with KBI, which is not routinely applied in such a setting due to the lack of evidence for clinical benefit. Moreover, 2 stents were implanted in 65% of patients. These data are not entirely commensurable with other contemporary studies in patients with true bifurcations. In comparison, in the provisional single-stent arm of the EBC MAIN trial, only 22% of the patients with a true distal left main bifurcation required a second stent. Hence the trial’s external validity may pertain more to complex PCI than to the totality of true bifurcation lesions.
Secondly, since the angiography guidance group did not have a blinded OCT assessment of its results, it may be difficult to say which specific OCT-triggered actions, contrasted with angiography guidance, contributed to the overall positive effects of its use. Therefore, a recommendation to use OCT for complex bifurcation PCI would have to entail following the OCTOBER-trial-specific protocol.
Results provide new evidence that OCT guidance may improve outcomes of bifurcation stenting that involves intervention on the side branch
Overall, the presented results provide new evidence that OCT guidance may improve outcomes of bifurcation stenting that involves any kind of intervention on the side branch (both POBA and a second stent). Taken together with other studies on intracoronary imaging presented in the same ESC Hot Line, mainly the ILUMIEN IV trial and a meta-analysis combining all randomized evidence, the OCTOBER trial seems to add to the message that the favourable clinical impact of intracoronary imaging increases with the complexity of PCI and the underlying coronary artery disease. Moving forward, and with the increasing adoption, the next task might be to understand which are the crucial elements of OCT guidance that are responsible for such favourable results.
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