Shedding the optical coherence tomography light on the treatment of complex coronary bifurcation lesions

The European Trial on Optical Coherence Tomography Optimized Bifurcation Event Reduction (OCTOBER) was an investigator-initiated, industry-funded, multicentre, open-label, randomized trial aiming to test the superiority of routine optical coherence tomography (OCT) guidance in percutaneous coronary intervention (PCI) of complex coronary bifurcation lesions as compared with angiographic guidance.1 • Patients with stable angina or non–ST-segment elevation acute coronary syndrome (NSTE-ACS) requiring PCI of a true bifurcation lesion (i.e. bifurcation lesions with both the main vessel and side branch having significant disease) were enrolled. Eligible bifurcation lesions required a main branch with a reference diameter ≥2.75 mm and a stenosis ≥50% on angiography and a side branch with a reference diameter ≥2.5 mm and a stenosis ≥50% within 5 mm from the ostium. Left main bifurcation lesions were included. The functional significance of the main branch stenosis required documentation by a noninvasive functional imaging test or a pressure wire–based method, unless an angiographic diameter stenosis >80% was present. Patients with an estimated glomerular filtration rate <50 mL/min/1.73 m2 were excluded. • Patients were randomized in a 1:1 ratio to OCT-guided PCI or angiography-guided PCI. In the OCT-guided PCI arm, a specific protocol defined the timing of OCT pullbacks (both in the main vessel and the side branch), as well as the recommended measurements, optimizations, and treatment goals (i.e. optimal stent coverage of the target lesion, optimal stent expansion, and absence of stent malapposition or accidentally crushed/distorted stents). In the angiography-guided PCI arm, intravascular ultrasonography (IVUS) was not encouraged but was allowed in case of left main bifurcation lesion. Conventional PCI bifurcation techniques were used,2 and the Xience everolimus-eluting stent was prespecified for implantation. The randomization was stratified based on the presence of a left main bifurcation lesion and on the PCI strategy (i.e. provisional single-stent technique vs. two-stent technique). • The primary endpoint was a composite of major adverse cardiac events (MACE), defined as cardiac death, target lesion myocardial infarction (MI), or ischaemia-driven target lesion revascularization (TLR) at a median follow-up of 2 years. Secondary endpoints included the single components of the primary endpoint and a patient-oriented composite endpoint of all-cause death, MI, any coronary revascularization, or stroke. • Between July 2017 and March 2022, a total of 1201 patients (mean age, 66 years; 21% female) were enrolled at 38 European institutions. A total of 227 patients (19% of cases) had a lesion located at the left main bifurcation. In the angiography-guided PCI arm, 15% of the patients underwent IVUS-guided PCI, of whom two-thirds had a lesion located in the left main bifurcation. The primary endpoint occurred less frequently in the OCT-guided PCI group than in the angiography-guided PCI group [10.1% vs. 14.1%; hazard ratio (HR), 0.70; 95% confidence interval (CI), .50–.98; P = .035], driven by numerically lower rates of all the single endpoint components (cardiac death: 1.4% vs. 2.6%; target lesion MI: 7.8% vs. 8.5%; ischaemia-driven TLR: 2.8% vs. 4.6%). The patient-oriented composite endpoint was less frequent in the OCT-guided PCI than in the angiography-guided PCI group (13.6% vs. 17.7%, respectively). The median volume of contrast used was larger in the OCT-guided PCI than in the angiography-guided PCI group {300 mL [interquartile range (IQR), 250–375] vs. 200 mL [IQR, 160–278]}, as well as the median procedural time [113 min (IQR, 85–145) vs. 80 min (IQR, 60–110)]