Angiographic co-registration of instantaneous wave-free ratio and intravascular ultrasound improves functional assessment of borderline lesions in the coronary artery

Instantaneous wave-free ratio (iFR) is a newly validated technique for evaluation of the functional severity of coronary artery disease [1, 2]. Particularly, iFR pullback assessment may map the ischemic contribution of each lesion within the same artery and provide guidance for percutaneous coronary interventions (PCI) [3]. However, standard manual or motorized pullback of a pressure guidewire with continuous iFR measurement can be associated with some inaccuracies when matching the iFR values with corresponding angiographic coronary lesions. Recently, the real-time co-registration of iFR measurements with their anatomical location has been introduced, significantly simplifying the overall examination and improving its accuracy. Moreover, the same concept of co-registration has also been employed for intravascular ultrasound (IVUS) and coronary angiography [4].
Herein, we present our first experience with the SyncVision Volcano system, which provides angiographic co-registration of both iFR and IVUS.
Our patient was an 83-year-old man who underwent primary PCI of the right coronary artery and was scheduled for the physiological assessment of a borderline lesion within the left anterior descending artery (LAD) (Figure 1 A). The measurement of fractional flow reserve (FFR) during adenosine infusion into the right femoral vein (140 µg/kg/min) yielded the value of 0.73. Distal iFR was 0.83; however, the pullback iFR assessment revealed steady growth of its value throughout LAD and one bigger increase (∆ 0.07) in the proximal part of the artery (Figure 1 B – see the diagram). This angiographic image and the corresponding iFR data indicated that there was a diffuse flow restriction within the distal and medial LAD and a tighter obstruction within the proximal LAD. Intravascular ultrasound with angiographic co-registration showed insignificant plaques in the distal and medial portion and a significant lesion in the proximal part of the LAD with minimal lumen area of 3.9 mm2 (Figure 1 C). Balloon pre-dilatation was performed with an NC Trek balloon (Abbott) 3.5/20 mm and then a drug-eluting stent Orsiro (Biotornik) 3.5/40 mm was implanted within the proximal LAD, and finally post-dilatation with an NC Trek balloon (Abbott) 4.0/20 mm was done. Repeated IVUS examination with angiographic co-registration revealed a good stent expansion and no edge dissection (Figure 1 D). The final functional measurements revealed residual flow restriction with iFR...


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