Validation of Quantitative Flow Ratio-Derived Virtual Angioplasty with Post-Angioplasty Fractional Flow Reserve-The QIMERA-I Study

Background: Quantitative flow ratio (QFR) virtual angioplasty with pre-PCI residual QFR showed better results compared with an angiographic approach to assess post-PCI functional results. However, correlation with pre-PCI residual QFR and post-PCI fractional flow reserve (FFR) is lacking. Methods: A multicenter prospective study including consecutive patients with angiographically 50-90% coronary lesions and positive QFR results. All patients were evaluated with QFR, hyperemic and non-hyperemic pressure ratios (NHPR) before and after the index PCI. Pre-PCI residual QFR (virtual angioplasty) was calculated and compared with post-PCI fractional flow reserve (FFR), QFR and NHPR. Results: A total of 84 patients with 92 treated coronary lesions were included, with a mean age of 65.5 +/- 10.9 years and 59% of single vessel lesions being the left anterior descending artery in 69%. The mean vessel diameter was 2.82 +/- 0.41 mm. Procedural success was achieved in all cases, with a mean number of implanted stents of 1.17 +/- 0.46. The baseline QFR value was 0.69 +/- 0.12 and baseline FFR and NHPR were 0.73 +/- 0.08 and 0.82 +/- 0.11, respectively. Mean post-PCI FFR increased to 0.87 +/- 0.05 whereas residual QFR had been estimated as 0.95 +/- 0.05, showing poor correlation with post-PCI FFR (0.163; 95% CI:0.078-0.386) and low diagnostic accuracy (30.9%, 95% CI:20-43%). Conclusions: In this analysis, the results of QFR-based virtual angioplasty did not seem to accurately correlate with post-PCI FFR.