Quantitative Flow Ratio to Predict Non-Target-Vessel Events Prior to Planned Staged PCI in ACS Patients
Authors: Bär Sarah , Kavaliauskaite Raminta , Otsuka Tatsuhiko , Ueki Yasushi , Häner Jonas , Lanz Jonas , Fürholz Monika , Praz Fabien , Hunziker Lukas , Siontis George CM , Pilgrim Thomas , Stortecky Stefan , Losdat Sylvain , Windecker Stephan , Räber Lorenz 
Published: July 2023

Background

The optimal timepoint of staged percutaneous coronary intervention (sPCI) among patients with acute coronary syndrome (ACS) and multivessel disease (MVD) remains a matter of debate. Quantitative Flow Ratio (QFR) is a novel non-invasive method to assess the hemodynamic significance of coronary stenoses. We aimed to investigate whether QFR could optimize the timing of sPCI of non-target-vessels (non-TV) among ACS patients with MVD.

Methods

For this cohort study, ACS patients discharged from Bern University Hospital, Switzerland, were eligible if non-TV sPCI was scheduled within 6 months after index PCI. The primary endpoint was non-TV myocardial infarction (MI) and urgent unplanned non-TV PCI before planned sPCI. The association between lowest QFR per patient measured in non-TV (from index angiogram) and the primary endpoint was assessed using a multivariable adjusted Cox proportional hazards regression with QFR included as linear and penalized spline (non-linear) terms.

Results

QFR was measured in 1093/1432 ACS patients scheduled to undergo non-TV sPCI. Median time to sPCI was 28 days. The primary endpoint occurred in 5% of the patients. In multivariable analysis (1018 patients), there was no independent association between non-TV QFR and the primary endpoint (HR 0.87, 95% CI 0.69-1.05 [per 0.1 increase], p=0.125; non-linear p=0.648).

Conclusions

In ACS patients scheduled to undergo sPCI at a median of 4 weeks after index PCI, QFR did not emerge as independent predictor of non-TV events prior to planned sPCI. Thus, this study does not provide conceptual evidence, that QFR is helpful to optimize the timing of sPCI.

Clinical Trial Registration

ClinicalTrials.gov:NCT02241291

Clinical Perspective

What is new?

This was the first study to investigate the association between non-target-vessel (non-TV) Quantitative Flow Ratio (QFR) and non-TV events occurring prior to planned staged percutaneous coronary intervention (PCI) among acute coronary syndrome (ACS) patients with multivessel disease, to derive first conceptual knowledge, whether QFR could be helpful to optimize the timing of staged PCI.

Among 1093 ACS patients and 1262 non-TV scheduled to undergo out-of-hospital staged PCI within a median of 28 days from index PCI, QFR did not emerge as an independent predictor of non-TV events occurring prior to planned staged PCI.

What are the clinical implications?

Among ACS patients in whom, according to the operator’s judgment, it is feasible to perform out-of-hospital staged PCI within a median of 1 month from index PCI, this study does not provide conceptual evidence, that QFR could be helpful to optimize the timing of staged PCI (i.e. to schedule staged PCI earlier in case of lower QFR).

Grapical Abstract

Study design (left) and primary endpoint results (right). For non-linear QFR, hazard ratios were calculated using the reference hazard corresponding to QFR=0.80 (grey dashed line) from a Cox proportional hazards model with penalized splines. ACS = acute coronary syndrome, CI = confidence interval, DS% = diameter stenosis, HR = hazard ratio, non-TV-MI = non-target-vessel myocardial infarction, non-TV-PCI = non-target-vessel percutaneous coronary intervention, PCI = percutaneous coronary intervention, QFR = Quantitative Flow Ratio, 1°EP = primary endpoint.