Hemodynamic assessment of pci using ultrasonic flow ratio in multivessel cad

Background Ultrasonic flow ratio (UFR) is a novel method for fast computation of fractional flow reserve (FFR) from intravascular ultrasound. Recently studies have shown the feasibility of morphofunctional computational methods to reliably estimate coronary physiology stemming from intravascular ultrasound images. Purpose The objective of the study was to evaluate the reasons for suboptimal physiological results after PCI using the UFR. Methods The study population comprised 150 consecutive patients (283 vessels) who underwent intravascular ultrasound for optimization of PCI in three-vessel-disease as mandated in the ongoing MULTIVESSEL TALENT trial (NCT04390672). The UFR analysis of final IVUS pullback was performed at the CORRIB Core Lab by an analyst who was blinded to the clinical data using a prototype software package (IvusPlus prototype, Shanghai Pulse Medical, Shanghai, China). Suboptimal physiological results were defined as post PCI UFR value of <0.91. UFR drop of ≥0.05 (gradient) was taken as a significant drop either intra or outside of the stent. Based on the definition of the HAWKEYE study, Focal lesions were defined as UFR drop of ≥0.05 in 10mm, diffuse lesions were defined as progressive decline of UFR of ≥0.05 without any clear evidence of focal drop, and mixed lesions were defined as the combination of focal and diffuse lesions. Results The median UFR with IQR among 283 vessels was 0.94 (0.91-0.97). Sixty-four (22.61%) of the 283 vessels had a UFR less than 0.91. We measured gradients using the UFR pull back curve intra-stent and outside of stent (Figure 1) in vessels with UFR <0.91. Significant "intra stent gradient", "out of stent gradient", combined "intra stent "and "out of stent" gradients were seen in 28 (44%), 18 (28%), and 10 (16%) vessels respectively. No clearly defined gradients were found in 8 (12%) vessels. Out of the 28 "out of stent" gradients, 20 were diffuse lesions, 5 were focal lesions and 3 was a mixed lesion. Conclusion IVUS has been widely used in optimization of PCI especially in scenarios with complex multi vessel disease. Combination of IVUS and FFR enable the operator to conform to the highest standards in PCI. This study has demonstrated that using UFR it is possible to identify the cause(s) of suboptimal PCI results and thereby to further optimize PCI results.