Non-invasive FFR Using Coronary CT Angiography and Computational Fluid Dynamics Predicts the Hemodynamic Significance of Coronary Lesions

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1 Non-invasive FFR Using Coronary CT Angiography and Computational Fluid Dynamics Predicts the Hemodynamic Significance of Coronary Lesions Andrejs Erglis, Sanda Jegere, Zanda Runkule, Ligita Zvaigzne, Dace Sondore, Indulis Kumsars, Inga Narbute, Iveta Mintale, Andis Dombrovskis, Gustavs Latkovskis Pauls Stradins Clinical University Hospital Riga, LATVIA

2 Disclosures Study supported by HeartFlow, Inc., Redwood City, CA, USA CT-FLOW analysis is an investigational technology and was performed by HeartFlow, Inc. Investigators have no financial interest in HeartFlow, Inc.

3 FFR Background Fractional flow reserve (FFR) during coronary angiography with adenosine induced hyperemia defines the hemodynamic significance of coronary artery lesions FFR-guided PCI improves the long term clinical outcome of patients with coronary artery disease (CAD) - DEFER and FAME studies Coronary CT has a high sensitivity and high negative predictive value for diagnosis of CAD However, coronary CT has a high false positive rate when compared to angiography with FFR and cannot define the hemodynamic significance of coronary lesions 75% false positives DEFER: Pijls JACC 2007;49:2105 FAME: Pijls JACC 2010;56:177 Meijboom, JACC 2008;52:636

4 Background Computational fluid dynamics (CFD), quantifies fluid pressure and velocity, based on physical laws of mass conservation and momentum balance CFD is widely used in the aerospace and automotive industries for design and testing CFD techniques have now been applied to solve problems of human blood flow Images courtesy of Prof. Charbel Farhat, Dept. of Aeronautics & Astronautics, Stanford University

5 CFD applied to coronary arteries CT-FLOW Simulated Hyperemic Blood Flow & Pressure CCTA 3D Model Supercomputer Equations of Blood Flow Physiologic conditions v, v v p t v 0 Coronary flow at rest Effect of hyperemia on microcirculation

6 Simulated blood flow & pressure during hyperemia

7 Computed FFR Mean coronary pressure is divided by aortic pressure in hyperemic state to compute FFR Simulated mean pressure with hyperemia FFR = Coronary / aortic pressure with hyperemia

8 Methods to correlate computed and measured FFR P Coronary P Aorta D model with computed FFR Model is rotated to same projection as angio with FFR measurement

9 Study Objective To evaluate the diagnostic performance of CT-FLOW in determining the hemodynamic significance of coronary artery lesions using FFR measured during coronary angiography as the reference standard

10 Methods 20 patients with known or suspected CAD underwent both coronary CT and angiography with FFR measurement Significant coronary stenosis was defined as 50% luminal diameter by coronary CT Hemodynamically significant stenosis at cath was defined at threshold values of 0.75 and 0.80 Computed FFR was determined in a blinded fashion by computational analysis based on the coronary CT scan

11 Patient and lesion characteristics Patients N=20 Age, mean ± SD 62.4 ± 8.3 years Male, n, % % Diabetes, n, % 3 15 % Hypertension, n, % % Hyperlipidemia, n, % % Smoking, n, % % Previous MI, n, % % Previous PCI, n, % 8 40 % LAD LCX RCA 8 (24.2%) 10 (30.3%) 15 (45.5%)

12 Coronary CT image CT-FLOW model with simulated hyperemia P Coronary P Aorta Measured FFR Computed FFR Model rotated to plane of angio

13 Coronary CT image CT-FLOW model with simulated hyperemia P Coronary P Aorta P Coronary P Aorta Measured FFR Computed FFR Model rotated to plane of angio

14 Measured FFR FFR Diagnostic Correlation CT-FLOW vs. FFR per lesion analysis (n=33) 1 0,8 0, False positives 0, , r=0.743 p<0.001 False negatives FFR CT-FLOW FFR: CT-FLOW: CT-FLOW Computed FFR

15 Diagnostic Performance Measures per patient analysis (n=20) True Positives False Positives True Negatives False negatives FFR < 0.80 FFR < 0.75 Coronary CT CT-FLOW Coronary CT CT-FLOW CT-FLOW: 3-fold reduction in false positives, zero false negatives

16 Diagnostic Performance Per-patient FFR 0.80 threshold* Coronary CT alone 100 CT-FLOW Sensitivity Specificity PPV NPV Accuracy *as per FAME study

17 Diagnostic Performance Per-patient FFR <0.75 threshold* Coronary CT alone 100 CT-FLOW Sensitivity Specificity PPV NPV Accuracy *As per DEFER study

18 Summary of Results Addition of CFD analysis to coronary CT (CT- FLOW) markedly improved the diagnostic accuracy for determination of hemodynamic significance of coronary artery disease - Diagnostic accuracy improved from 65% to 90% 0.80 FFR threshold - Diagnostic accuracy improved from 50% to 85% 0.75 FFR threshold

19 Conclusions CFD analysis of coronary CT imaging data can accurately assess the hemodynamic significance of coronary artery lesions CT-FLOW provides a non-invasive anatomic and functional assessment of CAD which may improve the selection of patients for coronary angiography and intervention Prospective, multicenter studies in larger patient cohorts are needed to validate these early findings