Trial finds OCT noninferior to IVUS in true distal left-main stenting

A split in the heart's main coronary artery leaves little room for error: the left main coronary artery supplies most of the blood to the left ventricle, and a stent must be placed where the vessel divides. In the ISOLEDS randomized trial, optical coherence tomography (OCT) was noninferior to intravascular ultrasound (IVUS) for guiding these procedures, in results presented at ESC Congress 2026.

Professor Yong Zeng of Beijing Anzhen Hospital, Capital Medical University, in Beijing, China, led the study. The open-label trial enrolled 664 patients with true distal left main bifurcation lesions at 24 centers in China, assigning them in equal proportions to OCT- or IVUS-guided percutaneous coronary intervention (PCI), the catheter-based procedure used to treat narrowed coronary arteries with a stent.

The trial's primary measure was target lesion failure at 12 months: cardiac death, a heart attack related to the treated lesion or another procedure to reopen that area. At a median follow-up of 362 days, the 12-month Kaplan–Meier estimates were 14.4% with OCT versus 19.6% with IVUS. The adjusted hazard ratio was 0.90, with a 95% confidence interval of 0.59 to 1.36 and a p value for noninferiority of 0.0003. The finding held when periprocedural heart attacks were excluded and in additional analyses.

The two tools show the artery in different ways. IVUS offers good tissue penetration and a large field of view. OCT provides a higher-resolution view of the vessel lumen and the stent. That distinction can matter at a branching point, but ISOLEDS does not show that one method is universally better: Zeng said the findings do not establish equivalence or superiority.

Concretely, the result gives clinicians treating appropriately selected distal left main bifurcation lesions another imaging option to consider. It does not replace IVUS or create a single preferred method. The choice remains dependent on the coronary anatomy, whether images can be acquired and local expertise.