Clinical significance of concordance or discordance between fractional flow reserve and coronary flow reserve for coronary physiological indices, microvascular resistance, and prognosis after elective percutaneous coronary intervention

Aims: We aimed to investigate the impact of concordance or discordance of fractional flow reserve (FFR) and coronary flow reserve (CFR) on coronary flow profiles and microvascular resistance after percutaneous coronary intervention (PCI), and the prognostic impact of the periprocedural physiological indices. Methods and results: A total of 249 de novo physiologically significant coronary lesions from 231 patients who underwent FFR, CFR, and index of microcirculatory resistance (IMR) examinations before and after PCI were included. Baseline characteristics and physiological indices were compared between the concordant (FFR <= 0.80 and CFR <2.0, n=114) and discordant (FFR <= 0.80 and CFR >= 2.0, n=135) groups. Follow-up data were collected to determine predictors of cardiac events. Shortening of the mean transit time, CFR improvement, and decrease in the hyperaemic IMR were all significantly greater in the concordant territories. Cox proportional hazards analysis showed that a lower pre-PCI CFR was an independent predictor of adverse events at a median follow-up of 26.5 months, whereas neither the pre- nor post-PCI FFR was predictive of events. Event-free survival was significantly worse in patients with a lower pre-PCI CFR. Conclusions: FFR/CFR concordantly abnormal territories provide a favourable benefit as assessed by coronary physiological indices after elective PCI. The pre-PCI CFR may predict adverse cardiac events.