Fractional Flow Reserve (FFR)

Transcription

1 Non-invasive FFR using coronary CT angiography and computational fluid dyn amics predicts the hemodynamic signifi cance of coronary lesions First in man experience with CT-Flow 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 Fractional Flow Reserve (FFR) Fractional flow reserve (FFR) is an index that determines the hemodynamic significance of coronary lesions; the ratio of maximal myocardial blood flow in the stenotic territory (Qs) to normal maximal myocardial blood flow (Qn) during hyperemia Q stenosis (P d -P v )/R s P d FFR = = = Q normal (P a -P v )/R n P a Q s myocardial blood flow in the stenotic territory Q n normal myocardial blood flow P a mean aortic pressure Aorta P d mean distal coronary pressure Max. hyperemia P v mean central venous pressure R s myocardial resistance in the stenotic territory R n myocardial resistance in the normal territory P a P a Coronary artery P d=a P d Myocardium Normal perfusion pressure P v P v Veins Q normal Q stenosis Bruyne BD, Sarma J. Heart 2008;94: Stenotic perfusion pressure

4 Ischemic Value of FFR FFR during coronary angiography with adenosine induced hyperemia is the reference standard for determining the hemodynamic significance of coronary artery lesions Normal value of FFR is 1.0. No ischemia Grey zone Ischemia FFR Pijls, De Bruyne et al, NEJM 1996

5 FFR-Guided PCI FFR-guided coronary revascularization (percutaneous coronary intervention, PCI) improves the long term clinical outcome of patients with coronary artery disease (CAD) Survival free from MACE Days since randomization DEFER: Pijls JACC 2007;49:2105 FAME: Pijls JACC 2010;56:177

6 Coronary CT angiography Coronary CT angiography (CCTA) is a non-invasive method in evaluation of coronary artery disease with a high sensitivity for detection of disease and a high negative predictive value for exclusion of obstructive lesions Sensitivity Specificity PPV NPV ACCURACY N=230, Stable Chest Pain; No known CAD; No exclusion (CACS, HR, BMI); CAD prevalence 13% CorE N=291, Stable Chest Pain; No known and Known CAD; Exclusion CACS>600; CAD prevalence 56% Meijboom N=360, Acute and Stable Chest Pain; No known CAD; CAD prevalence 68% Budoff MJ et al, JACC 2008;52: ; Miller JM et al, NEJM 2008;359: Meijboom WB et al, JACC 2008; 52:

7 CCTA vs. FFR However, CCTA has a high false positive rate when compared to angiography/ffr and cannot define the hemodynamic significance of coronary lesions FFR 75% false positives 75% of lesions with > 50% stenosis by CCTA are false positives Meijboom WB et al, JACC 2008;52:

8 Computational fluid dynamics 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 analyze problems of human blood flow Images courtesy of Prof. Charbel Farhat, Dept. of Aeronautics & Astronautics, Stanford University

9 CFD application to coronary arteries CT-FLOW CCTA 3D Model Supercomputer Simulated Hyperemic Blood Flow & Pressure Equations of Blood Flow Physiologic conditions Aortic pressure Coronary flow at rest Effect of hyperemia on microcirculation CT-FLOW is an investigational device

10 Computed blood flow & pressure Pressure Velocity Rest Hyperemia

11 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

12 Methods to correlate computed and measured FFR D model with computed FFR Model is rotated to same projection as angio with FFR measurement

13 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

14 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

15 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 %

16 Case Example #1

17 Case Example #1 CCTA: 3D

18 Case Example #1 CCTA: 2D

19 Case Example #1 CCTA: 2D

20 Case Example #1 Coronary Angiography

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

22 Case Example #2 Coronary Angiography

23 Case Example #2 Coronary Angiography

24 Case Example #2 CCTA: 2D

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

26 Case Example #2 PCI

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

28 Diagnostic Performance Measures for determining the hemodynamic significance of lesions 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

29 Diagnostic Performance Per-patient FFR 0.80 threshold* *as per FAME study

30 Diagnostic Performance Per-patient FFR <0.75 threshold* *As per DEFER study

31 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

32 Limitations Single center, first-in-man experience with new technology Small patient sample size

33 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

34 Thank you!