The relationship between coronary stenosis morphology and fractional flow reserve: a computational fluid dynamics modelling study

Roberto T F Newcombe; Rebecca C Gosling; Vignesh Rammohan; Patricia V Lawford; D Rodney Hose; Julian P Gunn; Paul D Morris

doi:10.1093/ehjdh/ztab075

The relationship between coronary stenosis morphology and fractional flow reserve: a computational fluid dynamics modelling study

Eur Heart J Digit Health. 2021 Aug 15;2(4):616-625. doi: 10.1093/ehjdh/ztab075. eCollection 2021 Dec.

Authors

Roberto T F Newcombe¹, Rebecca C Gosling^{1

2

3}, Vignesh Rammohan^{1

2}, Patricia V Lawford^{1

2}, D Rodney Hose^{1

2}, Julian P Gunn^{1

2

3}, Paul D Morris^{1

2

3}

Affiliations

¹ Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S102RX, UK.
² Insigneo Institute for in Silico Medicine, Frederick Mappin Building, Mappin St, Sheffield S1 3JD, UK.
³ Department of Cardiology, Chesterman Building, Sheffield Teaching Hospitals NHS Foundation Trust, Herries Road, Sheffield S5 7AU, UK.

Abstract

Aims: International guidelines mandate the use of fractional flow reserve (FFR) and/or non-hyperaemic pressure ratios to assess the physiological significance of moderate coronary artery lesions to guide revascularization decisions. However, they remain underused such that visual estimation of lesion severity continues to be the predominant decision-making tool. It would be pragmatic to have an improved understanding of the relationship between lesion morphology and haemodynamics. The aim of this study was to compute virtual FFR (vFFR) in idealized coronary artery geometries with a variety of stenosis and vessel characteristics.

Methods and results: Coronary artery geometries were modelled, based upon physiologically realistic branched arteries. Common stenosis characteristics were studied, including % narrowing, length, eccentricity, shape, number, position relative to branch, and distal (myocardial) resistance. Computational fluid dynamics modelling was used to calculate vFFRs using the VIRTUheart™ system. Percentage lesion severity had the greatest effect upon FFR. Any ≥80% diameter stenosis in two views (i.e. concentric) was physiologically significant (FFR ≤ 0.80), irrespective of length, shape, or vessel diameter. Almost all eccentric stenoses and all 50% concentric stenoses were physiologically non-significant, whilst 70% uniform concentric stenoses about 10 mm long straddled the ischaemic threshold (FFR 0.80). A low microvascular resistance (MVR) reduced FFR on average by 0.05, and a high MVR increased it by 0.03.

Conclusion: Using computational modelling, we have produced an analysis of vFFR that relates stenosis characteristics to haemodynamic significance. The strongest predictor of a positive vFFR was a concentric, ≥80% diameter stenosis. The importance of MVR was quantified. Other lesion characteristics have a limited impact.

Keywords: Computer modelling; Coronary artery disease; Fractional flow reserve.

Grants and funding

WT_/Wellcome Trust/United Kingdom