Frequency domain optical coherence tomography (FD-OCT) yielded accurate heart measurements and was more accurate than intravascular ultrasound (IVUS) in detecting certain stent abnormalities, according to a study published in the October issue of JACC: Cardiovascular Imaging.

In the Optical Coherence Tomography Compared to IVUS in Coronary Lesion Assessment (OPUS-CLASS) study, researchers led by Takashi Kubo, MD, PhD, of Wakayama Medical University in Wakayama, Japan, studied 100 patients with coronary artery disease (CAD) using quantitative coronary angiography (QCA), FD-OCT and IVUS. They also used FD-OCT and IVUS to inspect five phantom models with a lumen diameter of 3.08 mm and a lumen of 7.45 mm². An independent laboratory performed analyses of the coronary arteries and phantom models.

Among the patients, the average minimum lumen diameter measured by QCA was significantly smaller than the average minimum lumen diameter measured by FD-OCT (1.81 mm vs 1.91 mm). The average minimum diameter measured by IVUS was significantly larger than what was measured by FD-OCT (3.68 mm² vs 2.22 mm²). The researchers did find a significant association between IVUS and FD-OCT.

Interobserver reproducibility was good for both FD-OCT and IVUS, but the root-mean-squared deviation between the measurements was about twice as high for IVUS (0.32 mm² vs 0.16 mm²).

With a phantom model, FD-OCT determined the mean lumen area to be the same as the actual area. On the other hand, IVUS overestimated the area.

Additionally, “FD-OCT was much more sensitive in detecting intrastent tissue protrusion, incomplete stent apposition, stent edge dissection, and intrastent thrombus compared with IVUS,” the authors wrote.

While FD-OCT is gaining popularity as an assessment tool for CAD and a way to assist with PCI, it is still unclear which modality may be better able to improve clinical outcomes after stent placement, the authors explained.

In an accompanying editorial, three physicians agreed that more research is needed.

“Whether OCT is superior to (or as good as) IVUS in improving clinical outcomes when used to guide coronary intervention will only be answered by an adequately powered randomized trial,” wrote the authors, led by Akiko Maehara, MD, of Columbia University Medical Center in New York.

They added that although such a trial would be very expensive, the fact that millions of drug-eluting stents are placed around the world every year may warrant the costs.

“Until such a trial is complete, it is likely that the OCT versus IVUS debate will continue,” they wrote.