Residual Quantitative Flow Ratio to Estimate Post‐Percutaneous Coronary Intervention Fractional Flow Reserve

Abstract

Objectives. Quantitative flow ratio (QFR) computes fractional flow reserve (FFR) based on invasive coronary angiography (ICA). Residual QFR estimates post‐percutaneous coronary intervention (PCI) FFR. This study sought to assess the relationship of residual QFR with post-PCI FFR. Methods. Residual QFR analysis, using pre-PCI ICA, was attempted in 159 vessels with post-PCI FFR. QFR lesion location was matched with the PCI location to simulate the performed intervention and allow computation of residual QFR. A post-PCI FFR < 0.90 was used to define a suboptimal PCI result. Results. Residual QFR computation was successful in 128 (81%) vessels. Median residual QFR was higher than post-PCI FFR (0.96 Q1–Q3: 0.91–0.99 vs. 0.91 Q1–Q3: 0.86–0.96, p < 0.001 ). A significant correlation and agreement were observed between residual QFR and post-PCI FFR (R = 0.56 and intraclass correlation coefficient = 0.47, p < 0.001 for both). Following PCI, an FFR < 0.90 was observed in 54 (42%) vessels. Specificity, positive predictive value, sensitivity, and negative predictive value of residual QFR for assessment of the PCI result were 96% (95% confidence interval (CI): 87–99%), 89% (95% CI: 72–96%), 44% (95% CI: 31–59%), and 70% (95% CI: 65–75%), respectively. Residual QFR had an accuracy of 74% (95% CI: 66–82%) and an area under the receiver operating characteristic curve of 0.79 (95% CI: 0.71–0.86). Conclusions. A significant correlation and agreement between residual QFR and post-PCI FFR were observed. Residual QFR ≥ 0.90 did not necessarily commensurate with a satisfactory PCI (post-PCI FFR ≥ 0.90). In contrast, residual QFR exhibited a high specificity for prediction of a suboptimal PCI result.

Predictive value of the inconsistency between the residual and post-PCI QFR for prognosis in PCI patients

“…Previous landmark studies have demonstrated the instrumental value of the QFR in guiding the PCI procedure and further improving the clinical prognosis ( 10 – 12 ). The residual QFR is a predicted QFR value based on coronary angiographic imaging that simulates successful stent implantation in the culprit lesion, correlates well with the post-PCI FFR and QFR, and predicts the occurrence of adverse events after revascularization ( 13 , 14 , 16 , 22 ). A retrospective analysis of the PANDA III trial showed that the predicted clinical outcome of residual QFR-guided PCI was superior to that of angio-guided PCI ( 15 , 23 ).…”

“…The stent diameter in the underanticipated group in this study was smaller (2.96 ± 0.41 vs. 3.11 ± 0.44, P = 0.004) than that in the consistent group, supporting the previous hypothesis. A low residual QFR suggests that the target vessel may have a limited or diffuse lesion that the operator is unaware of or that the benefit of intervention for this coronary lesion is low, and this information may help to modify the PCI strategy ( 14 ). In addition, compared with the consistent group, the overanticipated group had a greater mean number of stents implanted (1.65 ± 0.62 vs. 1.23 ± 0.45, P < 0.001) and a longer total stent length (43.42 ± 17.47 vs. 30.80 ± 13.66, P < 0.001), which may have contributed to the greater post-PCI QFR than residual QFR in the overanticipated group.…”

“…The residual QFR is an essential indicator derived from the QFR computation procedure and can simulate the anticipated QFR value after successful revascularization based on pre-PCI angiographic images ( 13 ). Previous studies have reported that the residual QFR significantly correlates with the post-PCI FFR, especially in patients with suboptimal PCI results ( 14 ). Based on the residual QFR, a cardiologist can identify the major lesion from a functional perspective, further optimizing the PCI strategy.…”

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

“…Indeed, residual QFR predicts the results of a technically successful angioplasty and does not fully consider potential issues (such as stent under-expansion in severely calcified vessels) that can worsen the PCI results and impair actual post-PCI functional values. Another retrospective analysis with wider inclusion criteria was provided by Van Diemen et al [33], with all kinds of lesions suitable for post-PCI FFR and residual QFR evaluation. Correlation between residual QFR and FFR was good (r = 0.56), but again these results did not fully reflect common clinical practice, because post-PCI functional evaluation was performed only in the case of "successful angioplasty" defined by the operators.…”

Practical Application of Coronary Physiologic Assessment

“…Recent studies presented the feasibility of computed tomography–derived FFR or functional coronary angiography with virtual pullback technology in procedural planning. 86 , 91 , 92 Upcoming trials in this field will provide further data on the use of these methods. The AQVA (Angio-based quantitative flow ratio virtual PCI versus conventional angio-guided PCI in the achievement of an optimal post-PCI QFR; NCT04664140 ) study investigators are comparing QFR-based virtual PCI with conventional angiography–guided PCI in a prospective randomized fashion.…”