Optical Coherence Tomography May Improve Safety, Outcomes in Stenting Procedures

Compared to angiography-guided percutaneous coronary intervention (PCI), using optical coherence tomography to guide stent implantation during PCI may be safer and lead to better outcomes for heart disease patients. The findings are from the largest clinical trial of its kind comparing the two methods for this procedure. The “ILUMIEN IV: OPTIMAL PCI” study results were presented at the European Society of Cardiology Congress (ESC 2023) in Amsterdam, Netherlands, and published in The New England Journal of Medicine.

“Prior studies had demonstrated that intravascular imaging guidance of PCI procedures, particularly with intravascular ultrasound (IVUS), improves patient safety and clinical outcomes after coronary stent implantation. However, most of these trials were done outside the United States, and few tested PCI guided by OCT, which compared to IVUS offers superior resolution and accuracy,” says senior author Gregg W Stone, MD. Dr Stone is Director of Academic Affairs for the Mount Sinai Health System, Professor of Medicine (Cardiology), and Population Health Science and Policy, at the Icahn School of Medicine at Mount Sinai, and the study chairman of the ILUMIEN IV trial.

“The ILUMIEN IV trial demonstrated that OCT-guided PCI compared with angiography-guided PCI improves stent implantation results and the safety of the procedure, with less stent thrombosis, the most devastating complication of stenting,” Dr Stone adds. “However, while there were numerically fewer cardiac deaths and myocardial infarctions (MIs) in the OCT group, the differences between groups in the primary composite outcome of cardiac death or MIs or repeat revascularization related to the treated vessel was not significant.”

Patients with coronary artery disease—plaque buildup inside the arteries that leads to chest pain, shortness of breath, and heart attack—often undergo PCI, a non-surgical procedure in which interventional cardiologists use a catheter to place stents in the blocked coronary arteries to restore blood flow. Interventional cardiologists most commonly use angiography to guide PCI, which involves a special dye (contrast material) and X-rays to see how blood flows through the heart arteries to highlight any blockages.

Angiography has limitations, making it difficult to determine the true artery size and the makeup of the plaque, and is suboptimal in identifying whether the stent is fully expanded post-PCI and other complications that affect the safety and effectiveness of the procedure. Intravascular ultrasound (IVUS) is another technique that provides a more accurate and specific picture of the coronary arteries. Even though studies have shown that IVUS-guided PCI is superior to angiography-guided PCI and reduces cardiovascular events, it is only used in roughly 15 to 20 percent of PCI cases in the United States, since images may be difficult to interpret.

An even newer technique is OCT, which uses light instead of sound to create images of the blockages. OCT images are much higher in resolution, more accurate, and more detailed compared to IVUS, and easier to interpret. However, as a newer technique, OCT is used in only 3 percent of PCI cases, partly because of a lack of study data—something this new trial aims to change.

The ILUMIEN IV: OPTIMAL PCI trial randomized 2,487 patients to OCT-guided PCI using a device manufactured by Abbott Vascular and angiography-guided PCI between May 2018 and December 2020. The study took place at 80 centers in 18 countries and patients did not know what type of guided procedure they received. Researchers evaluated the dimensions of the stented area post-PCI since re-narrowing of the stent over time can lead to repeat revascularization procedures.

Overall, patients in the OCT group had a substantially larger stent area compared to the angiography-guided group immediately after the procedure—an increase of .36mm2. OCT guidance also led to fewer procedural complications than angiography guidance. Researchers also looked at target lesion failure (TLF)—the combination of cardiac death, target-vessel myocardial infarction, or ischemia-driven target-vessel revascularization. Two years after the procedure, 88 patients in the OCT group had TLF compared to 99 in the angiography group, a difference that did not reach statistical significance.

The study went further and analyzed rates of stent thrombosis, one of the most severe complications of PCI.  Within two years of PCI, six patients in the OCT group had stent thrombosis, compared to 17 in the angiography group, meaning that OCT reduced these instances by 65 percent. Additionally, 96 percent of patients who had a stent thrombosis in the trial died or had a subsequent myocardial infarction, emphasizing the importance of preventing these events.

“In summary, OCT guidance led to better implantation of the stent, a safer procedure, and a two-thirds reduction in stent thrombosis. The difference in TLF, while in favor of the OCT procedure, did not reach statistical significance in this trial, however, possibly due in part to the low rate of elective repeat procedures during the COVID-19 pandemic,” Dr Stone said.

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