Residual functional SYNTAX score by quantitative flow ratio and improvement of exercise capacity after revascularization in patients with stable ischemic heart disease

Abstract

Abstract Background In patients with stable ischemic heart disease (SIHD), the efficacy of percutaneous coronary intervention (PCI) in improving exercise capacity has been under debate and the differential effect of PCI for exercise capacity, according to functional completeness of revascularization, has not been evaluated. Purpose This study aimed to evaluate the association between improvement in exercise capacity and functional completeness of revascularization, determined by residual functional SYNTAX score (rFSS), which is the sum of residual SYNTAX score of the vessels with post-PCI quantitative flow ratio (QFR)≤0.80. Methods Among patients enrolled in the QFR multicenter registry, 110 patients who underwent prespecified routine exercise treadmill tests before and after PCI were analyzed. Patients were classified into functional complete revascularization (CR) group (rFSS=0) and functional incomplete revascularization (IR) group (rFSS≥1). Increase of exercise time after PCI was compared between the 2 groups. Improvement of exercise capacity was defined as ≥10% increase of exercise time after PCI. Results Functional CR was achieved in 79 patients (71.8%), otherwise classified as functional IR in 31 patients (18.2%). There were no significant differences in baseline characteristics including medication profiles. Increase of exercise time was significantly associated with increase of 3-vessel QFR (r=0.198, P=0.038) and rFSS (r=−0.312, P<0.001), but not with decrease of SYNTAX score (r=0.097, P=0.313). The rFSS showed significantly higher c-index to predict the improvement of exercise capacity after PCI than increase of 3-vessel QFR or decrease of SYNTAX score (0.722 vs. 0.627 vs. 0.492, respectively, P<0.001). Patients with functional CR, defined by rFSS, showed significantly higher increase of exercise time than those with functional IR (97.7 sec vs. 12.5 sec, P<0.001). Functional CR was an independent predictor of the improvement of exercise capacity after PCI (adjusted odds ratio 4.656, 95% CI 1.678–12.920, P=0.002). Conclusions Integrated anatomic and functional scoring system (rFSS) was significantly associated with improvement of exercise capacity after PCI. SIHD patients with functional CR, defined by rFSS, showed significantly higher exercise capacity after PCI than those with functional IR. Summarizing Figure Funding Acknowledgement Type of funding source: Private company. Main funding source(s): SaeHan NK & D and Medis Corporation