The impact of coronary chronic total occlusion percutaneous coronary intervention upon donor vessel fractional flow reserve and instantaneous wave-free ratio: Implications for physiology-guided PCI in patients with CTO.

Objective: To investigate the immediate and short term impact of right coronary artery (RCA) chronic total coronary occlusion (CTO) percutaneous coronary intervention (PCI) upon collateral donor vessel fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR). Background: CTO PCI influences collateral donor vessel physiology, making the indication and/or timing of donor vessel revascularization difficult to determine. Methods: In patients with RCA CTO, FFR, iFR, and collateral function index (FFRcoll) were measured in LAD and LCx pre-CTO PCI, immediately post and at 4 month follow-up. Results: 34 patients underwent successful PCI. In the predominant donor vessel immediately post PCI, FFR, and FFRcoll did not change (0.76 +/- 0.12 to 0.75 +/- 0.13, P=0.267 and 0.31 +/- 0.10 vs. 0.34 +/- 0.11, P=0.078), but iFR increased significantly (0.86 +/- 0.10 to 0.88 +/- 0.10, P=0.012). At follow-up, there was a significant increase in predominant donor FFR and iFR (0.76 +/- 0.12 to 0.79 +/- 0.11, P=0.047 and 0.86 +/- 0.10 to 0.90 +/- 0.07, P=0.003), accompanied by a significant reduction in FFRcoll (0.31 +/- 0.10 to 0.18 +/- 0.07 P<0.0001). These changes resulted in a reclassification of the predominant donor vessel from ischemic to nonischemic in 18% (FFR) and 25% (iFR) of the cases, respectively. Conclusions: Successful recanalization of an RCA CTO resulted in a modest but statistically significant increase in the predominant donor vessel immediately post CTO PCI in the case of iFR and at 4-month follow-up for FFR and iFR compared to pre-PCI with a concomitant reduction in collateral function.