ISOLEDS Trial Finds OCT Noninferior to IVUS for Guiding PCI in Distal Left Main Bifurcation Lesions

The ISOLEDS trial randomized patients 1:1 at 24 Chinese centers to OCT or IVUS guidance during PCI for distal left main lesions. Primary endpoint was target lesion failure (cardiac death, target-lesion MI, or clinically driven revascularization). Median follow-up reached 362 days with mean patient age 63.5 years. OCT yielded 14.4% event rate versus 19.6% for IVUS (adjusted HR 0.90, 95% CI 0.59-1.36, p for noninferiority 0.0003). Results held after excluding periprocedural MI and in per-protocol analyses.

Prior broad-population trials such as ILUMIEN IV and OCTIVUS demonstrated OCT noninferiority overall, yet lacked dedicated left-main bifurcation data where vessel size, side-branch assessment, and stent optimization differ. ISOLEDS fills this gap but remains limited by open-label design, single-country enrollment, and 12-month horizon. Operator expertise and image-acquisition feasibility likely influenced modality selection in real-world practice.

Longer-term follow-up and cost-effectiveness data are needed before guidelines shift. Evidence quality is moderate: a well-powered noninferiority RCT with consistent sensitivity analyses, yet underpowered for superiority and lacking external validation outside China. Next required study is a multicenter international trial with 3-5 year clinical and angiographic endpoints.

Evidence calibration: single randomized trial with 12-month primary endpoint can establish short-term noninferiority but cannot confirm equivalence, durability, or generalizability; multicenter replication with extended follow-up is required.