ILUMIEN III Compares OCT to IVUS and Angiography to Guide PCI

October 30, 2016—Results from the ILUMIEN III: OPTIMIZE PCI trial investigating adjunctive imaging modalities showed that the use of a novel optical coherence tomography (OCT)-based stent sizing strategy results in similar minimal stent area (MSA) compared to intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI). Imaging-guided PCI (with both OCT and IVUS) also resulted in improved stent expansion and acute stent-based procedural success compared to angiography-guided PCI.

The findings from the ILUMIEN III: OPTIMIZE PCI trial were reported in a Late-Breaking Trials session at TCT 2016, the 28th annual Transcatheter Cardiovascular Therapeutics scientific symposium in Washington, DC. The study was also published online by Lead Investigator Ziad A. Ali, MD, et al in The Lancet.

The ILUMIEN III: OPTIMIZE PCI trial was funded by St. Jude Medical and used the company's Optis Integrated and Ilumien Optis PCI optimization systems to assess patients randomized to OCT-guided stent implantation. St. Jude Medical announced  the commencement of the trial in June 2015. The background of the investigation is that compared to angiographic guidance, IVUS guidance has been shown to reduce major adverse cardiovascular events (MACEs) after PCI, mainly by resulting in a larger postprocedure lumen; additionally, OCT provides higher-resolution imaging than IVUS, although some studies have suggested it may lead to smaller luminal diameters after stent implantation.

As summarized in the TCT announcement, the ILUMIEN III: OPTIMIZE PCI study was a multicenter, prospective, randomized controlled trial conducted at 29 sites in eight countries. Patients undergoing PCI were randomly assigned 1:1:1 to OCT-, IVUS-, or angiography-guided stent implantation. 

OCT-guided PCI was performed using a specific protocol to determine stent length, diameter, and expansion according to reference segment external elastic lamina (EEL) measurements. All patients underwent final OCT imaging (blinded in the IVUS and angiography arms).

The study randomized 450 patients between May 2015 and April 2016. The investigators analyzed 415 final OCT acquisitions for the primary endpoint of post-PCI MSA, as measured by OCT at an independent core laboratory. 

The final MSA was 5.79 mm² (interquartile range [IQR], 4.54–7.34 mm²) with OCT guidance, 5.89 mm² (IQR, 4.67–7.8 mm²) with IVUS guidance, and 5.49 mm² (IQR, 4.39–6.59 mm²⁾ with angiography guidance. The MSA with OCT guidance was noninferior to IVUS guidance (one-sided 97.5% lower confidence interval, -0.7 mm²; P _{noninferiority} = .0014), but not superior (P = .42). 

The trend toward greater MSA with OCT guidance compared to angiography guidance did not reach statistical significance (P = .12). Minimal and mean stent expansion and acute procedural success were greater in the imaging-guided arms compared to angiography, reported the investigators at TCT.

Additionally, the investigators found that untreated major dissections were more common after IVUS-guided PCI than OCT-guided PCI (26.1% vs 13.6%; P  = .0091). In the angiography-guided group, the rate of untreated major dissections was 18.6% (P = .25). Similarly, compared with OCT guidance, untreated major stent malapposition post-PCI was more frequent with both IVUS guidance (20.7% vs 10.7%; P = .0221) and angiography guidance (31.4% vs 10.7%; P = .0001). 

The investigators advised that clinical follow-up is ongoing in order to determine the clinical relevance of these OCT-based findings, as there were only six (1.3%) procedural and seven (1.6%) 30-day MACEs, with no significant differences between groups.

In the TCT press release, Dr. Ali commented, “The results of the ILUMIEN III: OPTIMIZE PCI study show that using a specific reference segment EEL-based stent optimization strategy during OCT-guided PCI is safe and resulted in similar MSA compared to IVUS-guided PCI with fewer untreated major dissections and less major malapposition. OCT-guided PCI also led to greater stent expansion and procedural success compared to angiography-guided PCI." Dr. Ali added, “These results are encouraging, but further study is still needed to determine whether the advantages we have identified by utilizing OCT guidance will impact clinical outcome.”

The Cardiovascular Research Foundation’s Clinical Trials Center conducted the site management, data management and monitoring, biostatistics and data analysis, and core lab analyses for the trial.