Clinical outcomes of Fractional Flow Reserve-Guided Percutaneous Coronary Intervention By Coronary Flow Capacity Status in Stable Lesions

Abstract

Background: Coronary flow capacity (CFC) provides integrated information about coronary flow reserve (CFR) and hyperaemic coronary flow and is useful for identifying coronary flow limitation.

Aims: The aim of this study was to investigate the effect of percutaneous coronary intervention (PCI) on vessel-related major adverse cardiovascular events (MACE) according to CFC status in stable coronary lesions.

Methods: From a global, multicentre registry of comprehensive physiological assessment, a total of 1,397 patients (1,694 vessels) were analysed. Low CFC was defined for lesions with reduced CFR and inverse of hyperaemic mean transit time (1/hTmn). A predefined definition of CFC (CFR <2.0 and 1/hTmn less than the corresponding percentile) was assessed first in a multivariable marginal Cox proportional model with the interaction term between CFC status and PCI (performed or not), and then the optimal definition of CFC was explored.

Results: We observed a significant interaction between predefined low CFC and PCI (p=0.067). With the optimal definition of CFC (CFR ≤3.2 and 1/hTmn ≤2.8), the HR (95% CI) of PCI was 0.278 (0.103-0.751) and 1.393 (0.783-2.478) in lesions with low and normal CFC, respectively. If lesions with fractional flow reserve (FFR) ≤0.8 and normal CFC had been deferred, the number of PCI would have decreased by 64%.

Conclusions: FFR-guided PCI for low CFC lesions was associated with reduced incidence of MACE in low CFC but not in normal CFC lesions. Our results suggest the potential use of CFC in combination with FFR for optimising the indication for PCI by reducing potentially unbeneficial PCI.

Clinical trials registration: https://ichgcp.net/clinical-trials-registry/NCT03690713.

Conflict of interest statement

B.-K. Koo has received an institutional research grant from St. Jude Medical (Abbott Vascular) and Philips Volcano. I. Nuñez Gil has received personal fees from AstraZeneca/Medtronic outside the submitted work. J.-Y. Hahn has received a research grant from St. Jude Medical (Abbott Vascular). P. Salinas has received speaker fees from Terumo, Alvimedica, Biomenco, and Boston Scientific. J. Escaned has received personal fees from Philips Volcano, Boston Scientific, and Abbott/St. Jude Medical, outside the submitted work. All other authors/collaborators declare that there is no conflict of interest relevant to the submitted work.

Figures

Figure 1

CFC map. Scatter plot showing the distribution of 1,690 vessels by the inverse of mean transit time at hyperaemia (hTmn) representing coronary flow (X-axis) and coronary flow reserve (CFR) (Y-axis). Low coronary flow capacity (CFC) was defined as lesions with low CFR as well as low 1/hTmn. The optimal thresholds of CFR and 1/hTmn were determined according to the performance of multivariable Cox proportional models predicting vessel-related major adverse cardiovascular events (MACE). Interquartile ranges of CFR (1.8 to 3.8) and 1/hTmn (2.6 to 5.6) were tested (arrows indicate these ranges), resulting in CFR ≤3.2 and 1/hTmn ≤2.8 as the optimal thresholds for low CFC (pale area). Vessels with FFR >0.8 and ≤0.8 are shown as blue and red dots.

Figure 2

Survival from vessel-related major adverse cardiovascular events (MACE) according to CFC status. Kaplan-Meier curves showing survival from MACE comparing vessels with low CFC (CFR ≤3.2 and 1/hTmn ≤2.8) versus normal CFC. The comparisons are illustrated among PCI-treated vessels (A) and deferred vessels (B). P-values were based on the log-rank test.

Figure 3

Proposed PCI strategy using FFR and CFC. Sixty-four percent of the vessels indicated for PCI by FFR could be deferred on the basis of CFC status, because PCI to such vessels could increase the risk of future events. FFR-defined epicardial stenosis and CFC-defined flow limitation can provide complementary information regarding the optimisation of PCI indication to stable lesions.

Figure 4

Association of FFR, IMR, CFC, and event. Scatter plots of vessels showing index of microvascular resistance (IMR) and fractional flow reserve (FFR). Colour indicates CFC status: green as CFR >3.2 and 1/hTmn >2.8, red as CFR ≤3.2 and 1/hTmn >2.8, blue as CFR >3.2 and 1/hTmn ≤2.8, and purple as CFR ≤3.2 and 1/hTmn ≤2.8 (low CFC). Crosses indicate vessels that suffered from MACE.