Aim To evaluate the efficacy and safety of percutaneous coronary interventions using intravascular methods in patients with “false” bifurcation lesions of the left main coronary artery. Methods The study enrolled 162 patients with angiographically confirmed “false” bifurcation lesions of the LMCA. Participants were randomized into two groups using the envelope method, based on the selected imaging technique. In Group 1 (n = 81), intravascular ultrasound (IVUS) was performed, while Group 2 (n = 81) underwent optical coherence tomography (OCT). Following imaging and per inclusion criteria, 128 patients were ultimately included in the analysis. Patients with a minimal lumen area (MLA) < 6 mm2 in the distal LMCA underwent myocardial revascularization. In cases where MLA > 6 mm2 and fractional flow reserve (FFR) > 0.8 (n = 36), revascularization was deferred, and medical therapy was recommended. Provisional stenting was performed in both groups, with subsequent FFR measurement in both the main and side branches, as well as stent assessment using IVUS or OCT. If FFR in a native branch was < 0.8, a second stent was deployed using either the “reverse-crush” or “reverse-Culotte” technique. If FFR was > 0.8, the procedure was considered complete. Results At 12-month follow-up, in-stent restenosis occurred in 2.0% and 4.8% of patients in Groups 1 and 2, respectively (p = 0.590). Restenosis in the side branch was observed in 6.0% and 4.8% of patients (p = 1.000). Target lesion revascularization was performed in 2.0% of Group 1 patients (p = 0.489). Myocardial infarction (MI) was recorded in 8.0% of patients in Group 1 (p = 0.122), with stent thrombosis at the target lesion site being the cause in 4.0% (p = 0.498), and 2.0% of these cases proving fatal. Other MIs were attributable to lesions in non-target coronary arteries. Cardiac mortality was exclusively observed in Group 1, at 4.0% (p = 0.186). The cumulative incidence of major adverse cardiac events (MACE) was higher in Group 1 compared to Group 2, at 10.0% and 2.4%, respectively (p = 0.214). Conclusion The use of IVUS or OCT demonstrates equivalent efficacy in optimizing clinical outcomes for patients with “false” bifurcation lesions of the LMCA. Postprocedural FFR measurement facilitates the timely detection of residual ischemia and enables dynamic intraoperative decision-making, significantly enhancing the safety and effectiveness of PCI. © 2025 Elsevier B.V., All rights reserved.