Abbott aims to build optical coherence tomography into a preferred tool for guiding the placement of stents that increase blood flow to the heart muscle. But a pair of major late-breaking studies comparing OCT to other imaging techniques have delivered mixed results.
By emitting near-infrared light from a small catheter within the blood vessel, Abbott’s devices can offer three-dimensional cross-sections of the heart’s coronary arteries, highlighting plaque build-ups and blockages. Artificial intelligence-powered software then helps clinicians select a correctly sized stent and direct its deployment.
At the annual meeting of the European Society of Cardiology in Amsterdam, researchers presented one randomized trial that compared the use of OCT to traditional X-ray angiography in percutaneous coronary interventions, which enrolled nearly 2,500 patients with complex cases across 18 countries.
The use of OCT led to larger minimum stent areas during implantation—meeting the study’s co-primary imaging endpoint, which made sure that the stents were properly expanded across their entire length. Wider diameters are typically associated with fewer complications in the future.
The study, with its results simultaneously published in The New England Journal of Medicine, also showed a significantly reduced rate of blood clots forming within OCT-guided stents after two years.
However, the study missed its co-primary clinical endpoint, posting low and nearly identical two-year measurements that combined the number of patient cardiac deaths, heart attacks and instances where surgery was needed to reopen the targeted artery.
These blood vessel failures occurred in 88 OCT-guided patients and 99 angiography-guided patients, a difference that was not statistically significant. In a statement, Abbott said the miss may have been driven by the COVID-19 pandemic, as well as regional variations in routine practice and access to healthcare.
“The demonstration that stent thrombosis is reduced by approximately two-thirds with OCT is especially important as most patients who develop stent thrombosis die or have a heart attack,” said Gregg Stone, chairman of the study and professor of cardiology at the Mount Sinai Icahn School of Medicine.
“OCT guidance also reduced angiographic complications and led to better stent implantation,” said Stone, adding that the results should have a major impact on clinical practice.
A second study presented at ESC compared the use of OCT to intravascular ultrasound and found the success of the approaches to be relatively similar. Both imaging techniques can be used to assess the target blockage and optimize stent implantation, and both are recommended in international treatment guidelines.
This head-to-head trial—also funded by Abbott, as well as by Medtronic and the CardioVascular Research Foundation—studied about 2,000 patients at nine sites in South Korea.
It found OCT was non-inferior to intravascular ultrasound after one year of tracking the rates of cardiac-related death, myocardial infarction and target vessel revascularization. At the same time, the incidence of major complications during the procedure was statistically lower in the OCT group, at 2.2%, compared to 3.7%.