Positive Signs for OCT Guidance in PCI
PARIS, France—No fewer than 3 Hot Line presentations on May 20, 2015, at EuroPCR addressed the question of how well optical coherence tomography (OCT) might inform PCI.
One focused on how operators might use the imaging technology to guide decision making, while the others compared OCT with IVUS.
Presenting data from the observational ILUMIEN I trial, William Wijns, MD, PhD, of Cardiovascular Center Aalst (Aalst, Belgium), said the study was designed to “capture physician behavior.”
ILUMIEN I enrolled 418 subjects indicated for PCI in de novo coronary arteries at 40 centers in the United States, Europe, Japan, Hong Kong, Australia, and Canada. Procedures followed a specific sequence. After the initial angiography, fractional flow reserve (FFR) was performed, followed by OCT. “Prior to OCT recording, the planned strategy was carefully recorded, and after OCT, operators were free to change their plan or not,” Dr. Wijns explained. In cases involving intervention, FFR and OCT results again were evaluated so that operators could decide on whether additional steps were required to optimize PCI. After this optional optimization, final results were documented with FFR and OCT.
Per protocol, PCI was indicated when FFR values were ≤ 0.80. During optimization, there were no specific recommendations related to FFR. There were no upfront rules on how to interpret OCT before PCI, but “unsatisfactory results” during the optimization stage included edge dissection, malapposition, thrombus, and under-expansion.
“Much to our surprise,” Dr. Wijns noted, physicians changed their strategy based on the pre-PCI OCT in 57% of cases; choice of stent length was longer in 43% and shorter in 25%, while stent diameter was larger in 8% and smaller in 31%. After PCI, OCT influenced optimization in 27% of cases. “Altogether OCT impacted on the PCI procedure in 65% of patients pre-PCI and/or post-PCI,” he noted.
Researchers divided patients into 4 groups based on whether OCT guidance did or did not change strategy either before the initial PCI or during its optimization.
OCT May Go Above and Beyond FFR
When OCT was used, particularly after PCI, operators implanted more stents per patient. Post-PCI FFR was lower and minimal lumen area (MLA) smaller in patients whose procedures were optimized by OCT. Although procedure duration was longer, there was no significant increase in the amount of contrast used and no cases of contrast-induced nephropathy.
In addition, post hoc analysis revealed a lower rate of periprocedural MI, though the same pattern in overall 30-day MACE only reached a trend (table 1). Adverse outcomes, including MI and stent thrombosis, remained rare up to 1 year.
Notably, results for periprocedural MI followed a similar pattern when diagnosed by Third Universal Definition. “These are not just troponin bumps. These are true periprocedural MIs,” Dr. Wijns stressed.
Core lab analysis showed abnormal OCT findings to be “very common after successful PCI by angiography,” he reported. “OCT abnormalities deemed unsatisfactory by operators” during optimization were malapposition (14.5%), stent underexpansion (7.6%), and edge dissection (2.7%). Further optimization reduced malapposition as well as edge dissection.
The “hypothesis-generating observation [of reduced periprocedural MI with OCT guidance] should be tested prospectively and certainly inform the design of future randomized trials,” Dr. Wijns concluded, adding that further study on the OCT “parameters that predict clinical outcomes at 1 year is ongoing.”
Panel member Masahisa Yamane, MD, of Sayama Hospital (Saitama, Japan), asked if any procedural complications arose during OCT from the need for pressurized contrast or saline injection. “Not much,” Dr. Wijns replied. “If anything, adverse events were perhaps more related to the use of the pullback technique for pressure wires.”
In fact, pressure is not a concern, said panel co-chair Evelyn Regar, MD, of Erasmus Medical Center (Rotterdam, the Netherlands), noting that evidence has shown “if we use contrast injection for producing an OCT image, we increase the intracoronary pressure by less than 10 mm Hg, so this is not the cause of complications.”
OCT Matches IVUS
The session also included a presentation on the ILUMIEN II study by Gregg W. Stone, MD, of Columbia University (New York, NY).
“Numerous studies have found that the strongest procedural predictor of stent thrombosis and restenosis is the minimum stent area achieved after PCI,” Dr. Stone noted. IVUS, which achieves greater stent luminal dimensions, has been associated with better event-free survival compared with angiography alone, he explained. “OCT has superior resolution compared to IVUS. But given its limited depth penetration it’s unable to resolve the external elastic membrane—that is, the true vessel size—in most cases. So whether stent expansion, a surrogate of clinical outcomes, is as great with OCT [as with IVUS] is unknown.”
To assess the degree of stent expansion achieved after OCT vs IVUS guidance, Dr. Stone and colleagues retrospectively compared 354 patients who underwent OCT in the ILUMIEN I trial with 586 patients from the IVUS substudy of the ADAPT-DES trial. The researchers, having randomly chosen 1 lesion per patient for analysis, propensity matched 286 pairs based on reference vessel diameter, lesion length, calcification, and reference segment availability.
The primary endpoint of post-PCI stent expansion (defined as minimum stent area divided by the mean reference lumen area) was comparable between OCT and IVUS guidance, as were the rates of major stent malapposition, tissue protrusion, and stent edge dissection (table 2).
On post-PCI QCA, in-segment diameter stenosis was slightly though nonsignificantly greater with OCT guidance (13.0% vs 12.3%; P = .07) due to smaller MLD at the distal stent edge (2.3 mm vs 2.4 mm; P < .0001).
Multivariable analysis performed in the entire cohort of patients confirmed the similarity between OCT and IVUS apart from in-segment diameter stenosis being greater for OCT (P = .009).
Dr. Stone reported that the randomized ILUMIEN III trial is currently comparing the potential for angiography, IVUS, and OCT to guide stent implantation.
Trial Seeks OPINION of OCT’s Effect on Prognosis
A third presentation featured preliminary results from the OPINION study, which is testing the noninferiority of PCI guided by OCT—specifically high-resolution optical frequency domain imaging (OFDI)—compared with IVUS and the impact on clinical outcomes.
Takashi Akasaka, MD, PhD, of Wakayama Medical University (Wakayama, Japan), and colleagues are randomizing patients scheduled for DES implantation in de novo native coronary artery to OFDI or IVUS guidance. Thus far, 829 patients have been enrolled and follow-up is ongoing, he noted.
In early results, QCA performed immediately after PCI showed in-segment MLD to be similar between the 2 groups, with slightly smaller stent diameter under OFDI guidance (mean 2.93 mm vs 2.99 mm; P = .032).
Dr. Akasaka predicted that final 12-month data will be available at EuroPCR 2016.
1. Wijns W. ILUMIEN I primary endpoint results. Presented at: EuroPCR; May 20, 2015; Paris, France.
2. Stone GW. ILUMIEN II: Comparison of stent expansion guided by optical coherence tomography and intravascular ultrasound. Presented at: EuroPCR; May 20, 2015; Paris, France.
3. Akasaka T. OPINION: OPtical frequency domain imaging versus INtravascular ultrasound in percutaneous coronary InterventiON. Presented at: EuroPCR; May 20, 2015; Paris, France.
- The OPINION trial was sponsored by Terumo.
- Dr. Wijns reports that fees and honoraria on his behalf go to the Cardiovascular Research Center Aalst. He is a shareholder and non-executive board member of Argonauts Partners, Cardio3 Biosciences (now Celyad), and Genae. He has received institutional research grants from several pharmaceutical and device companies including Boston Scientific, St. Jude, and Volcano.
- Dr. Stone reports no relevant conflicts of interest.
- Dr. Akasaka reports receiving institutional grant/research support from and serving as a consulant for Terumo.