ILUMIEN I trial – OCT and documentary FFR were performed pre- and post-PCI in 418 patients (with 467 stenoses) with stable or unstable angina or NSTEMI. Based on pre-PCI OCT, the procedure was altered in 55% of patients by selecting different stent lengths (shorter in 25%, longer in 43%). Post-PCI OCT findings, such as malapposition, stent underexpansion and edge dissection, resulted in optimization in 25%. Physician decision-making was thus affected by OCT imaging prior to PCI and post-PCI.

ILUMIEN II trial – It compared the degree of stent expansion achieved after OCT-guidance to that achieved with IVUS-guidance. A higher prevalence of post-PCI stent malapposition, tissue protrusion, and edge dissections was detected by OCT. The rates of major malapposition, tissue protrusion, and dissections were similar after OCT- and IVUS-guided stenting. OCT and IVUS guidance led to a comparable degree of stent expansion.

ILUMIEN III trial - OCT-guided PCI using a specific reference segment external elastic lamina-based stent optimization strategy was found to be safe and yielded similar minimum stent area to that of IVUS-guided PCI.

The DOCTORS trial showed that OCT-guided PCI results in better functional outcome (as assessed by post-PCI FFR) compared with routine angiography-guided PCI in NSTE-ACS patients. There was a higher incidence of post-stent optimization procedures (such as overdilation and additional stent implantations) in the OCT group.

A Systematic Review and Bayesian Network Meta-Analysis of 31 Studies revealed that PCI guidance using either IVUS or OCT was associated with a significant reduction of major adverse cardiovascular events and cardiovascular death in comparison to coronary angiography.

A recent large observational study, based on the Pan-London (United Kingdom) PCI registry, suggested that OCT-guided PCI was associated with improved procedural outcomes, in-hospital events, and long-term survival in comparison with standard angiography-guided PCI.

We seem to have invaluable evidence to support the role of OCT in guiding PCI. It provides excellent imaging, allowing the assessment of the vessel wall and structure closest to histology in the cath lab.