Diagnostic and prognostic utility of fractional flow reserve for in-stent restenosis.

Background: Functionally optimizing percutaneous coronary intervention (PCI) with post-PCI fractional flow reserve (FFR) measurement has been associated with improved outcomes in native vessels. However, its role in in-stent restenosis (ISR) PCI is not well understood.

Methods: Consecutive patients undergoing PCI for stable angina or stabilized acute coronary syndrome enrolled in a PCI registry were included. FFR was measured pre- and post-PCI with the goal of further optimization of the PCI result based on post-PCI FFR. Target vessel revascularization (TVR) was evaluated in those with optimized FFR (≥0.86) in the ISR and native vessel lesions.

Results: There were 675 lesions in 574 patients who underwent pre- and post-PCI FFR with 101 lesions with ISR. ISR group was more likely to present with acute coronary syndrome and to have hypertension and chronic kidney disease. Both groups had long to diffuse disease. Median pre-PCI stenosis (70 %, IQR 60-80 %) and pre-PCI FFR (0.69 vs 0.70) were similar in native and ISR groups. There was similar and modest correlation between angiographic severity and pre-PCI FFR in native and ISR lesions (-0.57[-0.62 to -0.51] and -0.54 [-0.67 to -0.38], both p < 0.0001). Similar proportions of stenosis were functionally optimized to a post-PCI FFR ≥0.86 (66 % vs 71 %, p = 0.7). Despite functional optimization, TVR was significantly higher in ISR compared to native lesions [HR 0.71, 95 % CI 0.08-0.38 Log rank P < 0.001] even when ISR was treated with a drug-eluting stent.

Conclusions: Despite functional optimization by post-PCI FFR, TVR is significantly higher after ISR PCI.