October 31, 2016 — Optical coherence tomography (OCT) provides safe and improved guidance for patients undergoing percutaneous coronary intervention to treat coronary artery disease, according to results from the ILLUMIEN III: OPTIMIZE PCI trial. The trial sought to determine whether a novel OCT-based stent sizing strategy would result in a comparable or superior minimal stent area (MSA) as achieved with former stent implant imaging techniques.
Researchers from NewYork-Presbyterian/Columbia University Medical Center presented the results as part of the late-breaking clinical trials session at the Transcatheter Cardiovascular Therapeutics (TCT) conference this weekend in Washington, D.C. The study has also been published in The Lancet and is available online.
“The trial shows that OCT-guided stent implantation provides equally large luminal dimensions as other techniques with enhanced accuracy and precision,” said Gregg W. Stone, M.D., director of cardiovascular research and education at the Center for Interventional Vascular Therapy at NewYork-Presbyterian/Columbia University Irving Medical Center, professor of medicine at Columbia University Medical Center and study chairman of the trial. “Specifically, OCT allowed stenting to be performed with fewer dissections and malappositon, findings that have been associated with poor long-term results.”
Percutaneous coronary intervention (PCI) is a minimally invasive procedure that is primarily used to open a blocked coronary artery in order to restore blood flow to the heart. PCI is most commonly guided by angiography, which uses X-rays to view the blood vessels. However, the angiogram does not take into account details of the disease process of atherosclerosis, which happens in the wall of the artery. Angiography-guided PCI is imprecise, and is poor at identifying residual dissections, thrombus (blood clots) and plaque protrusion. Intravascular ultrasound (IVUS) can overcome these limitations by allowing for tomographic cross-sectional imaging of the vessel wall and has shown to reduce major adverse cardiovascular events. OCT is a newer imaging modality that provides higher resolution images than IVUS.
“We used a specific protocol of OCT which sized the coronary artery precisely, to see if it could provide advantages over angiography and be as good as or better than IVUS,” said Ziad A. Ali, associate director of translational medicine at the Center for Interventional Vascular Therapy at NewYork-Presbyterian/Columbia University Medical Center, assistant professor of medicine and the Louis V. Gerstner Scholar at Columbia University College of Physicians and Surgeons and principal investigator of the trial. “The superior resolution of OCT identified more dissections, malapposition and tissue protrusion compared with angiography or IVUS alone – while achieving improved stent expansion and procedural success when directly compared to angiography.”
OCT-guided PCI was non-inferior to IVUS for the primary study endpoint of acute procedural minimal stent area.
The study examined outcomes of 450 patients at 29 hospitals in eight countries between May 2015 and April 2016. Patients were randomly assigned to receive either OCT-guided PCI, IVUS-guided PCI or angiography-guided PCI. It is the first study of its kind to compare all three modalities. All patients received clinical follow-up at 30 days and again at one year.
“ILUMIEN III: OPTIMIZE PCI is an important step toward our ultimate goal of improving patient outcomes with imaging during stenting.” said Stone. “These results have set the stage for a larger randomized trial, ILUMIEN IV, which is currently being planned to determine whether OCT-guidance results in superior clinical outcomes compared to angiography-guidance.”
Between May 2015 and April 2016, 450 patients were randomized and 415 final OCT acquisitions were analyzed for the primary endpoint of post-PCI MSA, measured by OCT at an independent core laboratory. The final MSA (median [25%, 75%]) was 5.79 [4.54, 7.34] mm2 with OCT-guidance, 5.89 [4.67, 7.80] mm2 with IVUS-guidance and 5.49 [4.39, 6.59] mm2 with angiography-guidance. The MSA with OCT-guidance was non-inferior to IVUS-guidance (one-sided 97.5% lower confidence interval = -0.70 mm2, Pnoninferiority=0.0014), but not superior (P=0.42).The trend toward greater MSA with OCT-guidance compared to angiography-guidance did not reach statistical significance (P=0.12). Minimal and mean stent expansion and acute procedural success were greater in the imaging-guided arms compared to angiography.
Untreated major dissections were more common after IVUS-guided PCI than OCT-guided PCI (26.1 vs. 13.6%, P=0.0091). In the angiography-guided group, the rate of untreated major dissections was 18.6% (p=0.25). Similarly, compared with OCT-guidance, untreated major stent malapposition post-PCI was more frequent with both IVUS-guidance (20.7 vs. 10.7%, P=0.0221) and angiography-guidance (31.4 vs. 10.7%, p<0.0001). Clinical follow-up to one-year 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 MACE events, with no significant differences between groups.
The study was funded by St. Jude Medical.
For more information: www.crf.org/tct