Assessment of vessel lesions using optical ultrasonic flow ratio (OUFR) based on hybrid intravascular ultrasound-optical coherence tomography (IVUS-OCT) is safe and effective and provided better diagnostic performance vs. fractional flow reserve (FFR) than OUFR based on either IVUS or OCT alone, according to a new study published Jan. 14 in JACC: Asia.

In this prospective, single-center study, from February 2023 to June 2023, Jiawei Zhao, MD, et al., assessed 80 patients (126 vessels) presenting with unstable angina pectoris using guidewire-based FFR as the reference standard and IVUS-OCT before PCI.

Then, they assessed 86 vessels in 61 patients (average age 61.2 years, 70.5% men, mean FFR 0.83) with OUFR based on OCT (OUFR_O) and hybrid IVUS-OCT (OUFR_OI), and 80 vessels in 58 patients (average age 61.3 years, 72.4% men, mean FFR 0.77) with OUFR based on IVUS alone (OUFR_I).

Results showed high agreement between FFR and all three OUFR indexes. Of note, the correlation with FFR was higher with OUFR_OI (r=0.88; p<0.001) and OUFR_O (r=0.85; p<0.001) than with OUFR_I (r=0.73; p<0.001).

Diagnostic accuracy for predicting FFR ≤0.80 was further improved when using both IVUS and OCT (OUFR_OI), with an accuracy, sensitivity and specificity of 95%, 94% and 96%, respectively. Furthermore, OUFR_OI performed better than the other two strategies with an area under the curve of 0.99, vs. 0.95 for OUFR_O and 0.91 for OUFR_I.

"The key idea for computing OUFR_OI was to substitute IVUS images in places where OCT images had incomplete blood clearance that might affect precise delineation of the luminal borders," write the authors. "Hybrid IVUS-OCT systems can combine the advantages of both technologies, overcome the limitations of each modality, and reduce the potential risk of cost and complications."

In an accompanying editorial comment, Masaru Ishida, MD, PhD, notes several promising applications. "Combining physiological and morphological data using the hybrid IVI system could enable 'flawless stent implantation' ensuring optimal post-PCI outcomes," writes Ishida. "By combining both IVI modalities, the hybrid IVI system has the potential to serve an 'all-in-one' imaging modality for PCI optimization."