10th Gulf Heart Association Conference, Riyadh 2013
CT Functional Flow Reserve Koen Nieman, MD, FESC Departments of Cardiology & radiology Erasmus MC, Rotterdam, The Netherlands
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Coronary CT Angiography
Meijboom, JACC 2008
Decision making
Tonino, et al, NEJM 2009
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Wijns et al, Nucl Cardiol 2007
52-years-old Man
• • • • •
1995 A-Flutter ablation; pos fam Hx CVD Progessive angina unresponsive to betablockers and nitrates XECG: 3 mm ↓ST on XECG severe Mid-LAD lesion Everolimus-eluting, bioresorbable poly-lactic acid scaffold Prospective, open-label, FIM trial in de novo 1VD (N=30)
5yr CT FU
7 6 5 4 3
3.7 mm2
2 1 0
5.9 mm2 (5.0 mm2)
5.0 mm2
Max area stenosis: 35%
5yr CT FU
7 6 5 4 3
3.7 mm2
2 1 0
5.9 mm2 (5.0 mm2)
5.0 mm2
Max area stenosis: 35%
0.87 0.76
FFRinv 0.75 0.71
Computational FFR simulation
How does it work?
Simplified Inflow:
Output P - aorta
Vessel model:
Outflow:
LV mass P - Venous
Computational flow: - Blood is a Newtonian fluid with a given viscosity - Assess flow and pressure at rest - Re-assess assuming low peripheral resistance
Is the model sufficient? Supply
Functional obstr. Microvascular obstr.
Perfusion pressure
Demand Scar hibernation
Bypass / collaterals
Assumptions: LV mass and vessel diameter equal flow Simulated pressure drop equals myocardial ischemia
CT image processing
“Reality”
Sample
Interpolated
Fixed
Accuracy of the CTA?
Busch Eur Rad 2007
Kappa 0.72 Dewey,, IJCI 2007
FFRCT versus FFRinv
Koo, et al, JACC 2011
Koo, et al, JACC 2011
Diagnostic performance of CTA (per patient analysis) Meta-analysis
Discover-FLOW
[Sun, JCCT 2012]
[Koo, JACC 2011]
Sens
99%
94%
Spec
91%
25%
PPV
94%
58%
NPV
99%
80%
DeFACTO Trial • Assess the value of CTA + FFR-CT to detect hemodynamically significant CAD • Multicenter randomized controlled trial
• • • •
N = 252 (285), suspected/known CAD Age 63, 70% male Selected after ICA been planned (<2M) S = 17 15 patients per site per year
Methodology • • • • • •
64+ CT technology Blinded corelab: CTA, FFR-inv, FFR-CT CTA >50% = angiographically significant FFR <0.80 = hemodynamically significant CTA >90% FFR-CT = FFR-inv = 0.50 [17%] CTA <30% FFR-CT = FFR-inv = 0.90 [45%]
Hypothesis • CTA/FFR-CT accuracy with 95%CI >70%
N=285 N=252 172 FFR-CT <0.80 116 FFR-inv <0.80
56 FFR-inv >0.80
80 FFR-CT >0.80 13 FFR-inv <0.80
67 FFR-inv >0.80
CTA >50% 64 58-70
FFRCT <0.80 73 67-78
Sensitivity
84 77-90
90 84-95
Specificity
42 34-51
54 46-83
PPV NPV
61 53-67 72 61-81
67 60-74 84 74-90
Accuracy
0.81
0.68
FFR-CT vs FFR-inv: R = 0.63, underestimation by FFR-CT: 0.06
Min et al, JAMA 2012
Technical Feasibility?
Conclusions • Need for Fx assessment after positive CT • Advantages of CT-FFR: – No further testing required – Lesion specific assessment – Prediction of effect of intervention
• Drawbacks of (HeartFlow) CT-FFR: – It is just not the same as invasive FFR, which is not the same as myocardial ischemia – Methodological uncertainties of FFR-CT – Practical limitations – Modest accuracy – Delay and expenses
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Future 1-Stop Shop?
0.86
0.92
Myocardial Perfusion CT
Hybrid PET-CT
Simulated FFR on CTA
0.93