Intracoronary optical coherence tomography (OCT) allows for high-resolution in-vivo visualization of coronary lumen, plaque characteristics, and stent expansion and apposition. Fractional flow reserve (FFR) is the current gold standard used for functional evaluation of coronary artery stenosis. Recently, researchers developed the optical flow ratio (OFR) method to determine FFR from OCT images. Next, they wished to explore concordance between OFR and FFR via a meta-analysis of studies which contained both measurements.
The meta-analysis included five studies which provided 574 patients and 626 vessels for consideration. Of the 626 vessels, 404 were pre-percutaneous coronary intervention (PCI) and 222 were post-PCI. Investigators designated the primary outcome as the vessel-level diagnostic concordance of OFR with wire-based FFR as the reference standard. For pre-PCI vessels, investigators defined the diagnostic accuracy of the OFR as the proportion of vessels with both OFR and FFR values of 0.80 or >0.80. For post-PCI vessels, a cut-off value of 0.90 for both OFR and FFR defined suboptimal stenting.
High concordance between optical flow ratio and fractional flow reserve
Investigators discovered an overall vessel-level diagnostic concordance of the OFR and FFR of 90% (95% confidence interval [CI], 87-92%). Comparing diagnostic concordance between pre- and post-PCI vessels, the concordance in pre-PCI vessels was 91% (95% CI, 88-94%), and 87% (95% CI, 82-91%) in post-PCI vessels. They calculated a sensitivity of 84% (95% CI: 79%-88%) associated with the OFR method, and a specificity of 94% (95% CI: 92%-96%).
Investigators concluded that OFR demonstrated high diagnostic accuracy in this meta-analysis. They propose that OFR could improve integration of intracoronary imaging and functional assessment for reliable evaluation of coronary artery disease. The authors call for further prospective studies which investigate the prognostic value of OFR.
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Author: Kelly Schoonderwoerd
Original Article: Hu et al. EuroIntervention March 2023.