CORONARY PRESSURE MEASURENT AND FRACTIONAL FLOW RESERVE

Jan Willem Bech, MD, PhD

Coronary pressure measurement and Fractional Flow Reserve in special situations.

Edinburgh, october 25th, 2002

Aorta coronaryartery

Myocardium

100 0

Normal perfusion pressure

Pa

100 Pd0

Stenotic perfusion pressure

Pa

Qnormal

Qstenosis

Qstenosis Stenotic perfusion press. Pd

FFR = = = Qnormal Normal perfusion press. Pa

Max. hyperemia

Pd

Characteristics of FFR

• FFR is not influenced by changes in blood pressure, heart rate, or contractility

• FFR has a unique normal value of 1.0 in every patient and every coronary artery

• FFR incorporates the contribution of collateral flow to myocardial perfusion

FFR threshold for ischemia

FFR

Noischemia

Yes ischemia

1.00 0.75 0.00

FFR < 0.75 inducible ischemia (spec. 100 % )FFR > 0.75 no inducible ischemia (sens. 90 % )

Pijls, De Bruyne et al, NEJM 1996

FFR < 0.75 ischaemia inducible: revascularization is justified.

FFR > 0.75 ischaemia highly unlikely: ? is it justified to DEFER revascularization, even

when the lesion is angiographically serious?

DEFER STUDY: 325 pat. all accepted for elective PTCA of a single lesion.

Just prior to PTCA FFR was determined.

Decision making based on FFR 0.75

Bech et al, Circulation 2001

DEFER study

325 patients144 patients FFR

< 0.75 => Ischaemia

PTCA 144 patients

181 patients FFR > 0.75 => No ischaemia

Randomisation

Performance of PTCA 90

patients

Deferral of PTCA 91 patients

Bech et al, Circulation 2001

2 yr follow-up2 yr follow-up

DEFER 2 jaar follow-up: event-free survival

Bech et al, Circulation 2001

0 6 12 18 2450

60

70

80

90

100

FFR 0.75. Geen PTCA

FFR 0.75. Wel PTCA

83%

89%

Maanden

Pe

rce

nta

ge

pati

en

ten

vri

j v

an

ev

en

ts

No PTCA

PTCA

The DEFER Study: Conclusion

In patients admitted for PTCA of a single lesion, but with a FFR more than 0.75 just prior to PTCA, deferral of revascularization is at least as good as performance of an intervention.

Although these patients have angiographic CAD and are at increased risk for events as compared to the general population we can conclude that performance of an intervention does not reduce this risk.

FFR to evaluate PTCA

FFR after coronary intervention should preferably be higher than 0.90

POBA: Follow-up 2 years: FFR < 0.90 event rate 41 % FFR > 0.90 event rate 15 % (Bech et al, Circulation 1999)

Multicenter registry Europe-USA-Asia750 pat. post-STENT FFR

0.96-1.000.86-0.90 0.91-0.950.81-0.850.76-0.800%

10%

20%

30%

40%

% death, infarction, or re-intervention at 6 mnths.

4%

7%

19%

28%

37%

Post-STENT FFR

After stenting: Inverse correlation between FFR and event rate.

How does FFR works in complex coronary

disease?

• difficult anatomy, poorly visible lesions, overlap

• multiple stenoses within one artery

• diffuse disease

• left main disease

• multivessel disease

CORONARY PRESSURE MEASUREMENT

LAD D 1D 2

Male, 67, stable angina, positive exercise test

RCA

LCX

2 intermediate stenoses mid RCA Complex lesion proximal LAD

0

100

FFR = 92/98 = 0.94

Pa

Pd

Pa

Pd

LAD, hyperemia

FFR = 87/97 = 0.890

100

Pa

Pd

Pa

Pd

DIAG 2, hyperemia

FFR = 87/96 = 0.900

100

Pa

Pd

Pa

Pd

DIAG 1, hyperemia

0

100Pa

PdFFR = 38/92 = 0.41

RCA, hyperemia

Balloon 3.0 mm

FFR = 55/82 = 0.67

100

0

Pa

Pd

After balloon inflation3.0 balloon 12 atm

Stent 3.5 mm(mid-RCA)

Stent 3.5 mm(mid-RCA)

FFR = 76/95 = 0.80

100

0

Pa

Pd

Pull back pressure wire

Pressure drop

Additional Stent 3.5 mm (prox-RCA)

Stent 3.5 mm(mid-RCA) +Stent 3.5 mm(prox-RCA)

FFR = 88/94 = 0.94

100

0

Pa

Pd

Pressure Wire:Use during complex interventions

In this patient with complex coronary artery disease,coronary pressure measurement:

• confirmed the appropriateness of stenting the RCA while avoiding a riskful intervention of the LAD or bypass surgery

• Selected the correct spots in the RCA where to stent

• evaluated the result of stenting.

How does FFR works in complex

coronary disease?

• difficult anatomy, poorly visible lesions, overlap

• multiple stenoses within one artery

• diffuse disease

• left main disease

• multi vessel disease

CORONARY PRESSURE MEASUREMENT

AB

Coronary Pressure & FFR: Pull-Back Curve

Focal disease: sudden changes in pressure

Coronary Pressure & FFR: Pull-Back Curve

Diffuse coronary disease: gradual increase of pressure.

• By slowly retrieving the pressure wire under fluoroscopy and sustained hyperemia

• the individual contribution of every segment of the coronary system to the extent of disease can be studied and such spatial information cannot be obtained by any other method

FFR: The Pressure Pull-back Curve

How does FFR works in complex coronary

disease?

• difficult anatomy, poorly visible lesions, overlap

• multiple stenoses within one artery

• diffuse disease

• long and ostial lesions

• left main disease

• multivessel disease

CORONARY PRESSURE MEASUREMENT

Decision making in equivocal left main coronary artery

disease by Fractional Flow Reserve

Bech et al, Heart 2001

Background

•The presence of angiographic clearly significant LMCA stenosis is often decisive in the choice for surgical treatment.

•However, often patients are encountered with angiographically an intermediate LMCA stenosis of unclear physiological significance.

•It is unclear whether bypass surgery should be performed.

Aim of the study

•To investigate the usefulness of pressure derived FFRto decide between medical versus surgical therapy in patients with equivocal LMCA disease.

Events during follow-up54 patients

FFR > 0.75N=24

Medical Group

FFR < 0.75N=30

Surgical Group

Mean follow-up (mths) 28 15 2914

Death 0 1

MI 0 1

Early re-operation -- 3

CABG 3 0

PTCA 2 0

Total 5 (21%) 5 (17%)

Conclusion

•FFR is useful in equivocal left main coronary artery disease.

•If LM FFR 0.75, a conservative medical of the LM lesion approach seems to be safe.

•If LM FFR < 0.75, the stenosis bears physiologic significance which justifies bypass surgery of the LM lesion.

How does FFR works in complex coronary

disease?

• difficult anatomy, poorly visible lesions, overlap

• multiple stenoses within one artery

• diffuse disease

• long and ostial lesions

• left main disease

• multivessel disease (submitted for publication)

CORONARY PRESSURE MEASUREMENT

Background 1

In multi-vessel disease,

• The most important prognostic index to predict outcome is the extent and severity of inducible ischemia.

• It has been demonstrated that from a symptomatic and prognostic point of view revascularization is indicated only for functionally significant (culprit) stenoses.

• In order to choose the optimum treatment, it is of paramount importance to know which of the angiographic stenoses are culprit and which are not.

• In multi-vessel disease, non-invasive testing can often not indicate which lesions are culprit.

• Fractional Flow Reserve can assess if a specific stenosis or segment is culprit or not by the ischemic threshold value of 0.75.

Background 2

• Not to answer the question whether CABG or PCI is a better treatment in all patients with multivessel disease

• But to investigate which is the optimum treatment in an individual patient with multivessel disease.

• CABG for a patient with a large area at risk versus PCI for a patient with a limited area at risk.

Aim

Inclusion

• Patients with angiographically MVD

• Technically suitable for CABG or PCI

Procedure

• Multivessel coronary pressure measurement by the so called “pull-back procedure” was performed.

• A coronary artery was defined as culprit when FFR < 0.75.

• If 3 or 2 (including LAD) culprit arteries CABG was performed.

• If 1 or 2 (excluding LAD) culprit arteries PCI was performed.

Conclusion

In multi-vessel disease, coronary pressure measurement is an excellent tool to identify the culprit lesion(s) by FFR < 0.75 and facilitates the choice for the optimum treatment modality (CABG or PCI)