Discordance of CTA / Nuclear/ Cath
which one to Believe ?
Khalid ALNemer
MD, FRCPC, FACC, FASCI, FASNC, FSCCT.
Interventional,CT/Nuclear Cardiologist.
Chairman of Professional Education Committee SHA .
Chairman of cardiac imaging society .
Clinical Ass. Professor of Cardiology King Saud University .
Director of Cath Lab at Security Forces Hospital.
.
Agenda…..
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Disclosure …..
Survey questions
Limitations of each test
Causes of disagreement
How to correlates ?
A case senario !
Take home messages…..
Q1. Is there a discordance exist between cath
and nuclear?
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Yes
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NO
Q2. if it is exist , then how common?
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>70%
50-70%
<50%
Q3.is every 90% coronary lesion is functionally
significant?
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A:YES
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B:NO
Q4. what is the percentage of lesions >70% which are not
functionally significant?
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A : <10%
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B:10-50%
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C:>50%
in early 2012:
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FAME II
VS. Courage trials
Why does cath underestimate original vessel size ?
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atherosclerosis positive remodeling effect.
the segments proximal and distal to the stenosis used for
reference are affected by atherosclerosis themselves.
Am J Cardiol 2001;88:294-6.
Limitations of coronary Angiography
Poor Correlation with Physiology
4.8
r = -0.35
3.6
Coronary
reactive
hyperemia
peak/resting 2.4
velocity ratio
1.2
0
0
20
40
60
80
100
% diameter stenosis
single lesions only)
White, CW et.al., Does visual interpretation of
(LAD
arteriogram predict the physiological importance
of a coronary stenosis, NEJM, 1984; 310: pp 819-24
regarding significance : anatomy = physiology
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250 pts scheduled for PCI .
All stenoses ≥50% by visual estimation and initially selected to be
stented by 3 independent internvetional cardiologists reviewers .
assessed by FFR measurements.
in 32% of stenoses, there was a change in the planned approach
based on FFR.
in this prospective, nonselective, complete study representing the real
world of PCI, 32% of the coronary stenoses and 48% of patients would
have received a different treatment if the decision had been based on
angiography only, stressing the utility of physiologic assessment in
refining decision making during PCI.
The American Journal of Cardiology
Vol 99(4) , 15 February 2007, P. 504-508
Nuclear vs. cath ?
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measure different variables……
Different limitations……
Shouldn’t be compared head to head…
complementary to each other…
They are not expected , nor supposed
to agree with each other all the time !!
Meta-analysis of FFR vs. QCA and MPI for evaluation of myocardial
ischemia.
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meta-analysis of 31 studies
Across 18 studies (1,522 lesions) :
QCA SN 78% (95%CI:67-86)
SP 51% (95%CI: 40-61)
Overall concordances :
against FFR.
61% for stenosis 30 – 70 %,
67% for stenoses >70%,
95% for stenoses <30%.
Conclusion :
QCA does not predict the functional significance of coronary lesions.
Am J Cardiol. 2007 Feb 15;99(4):450-6
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Compared with noninvasive imaging (21 studies, 1,249 lesions),
FFR SN 76% (95%CI : 69-82)
SP 76% (95% CI 71-81)
Summary receiver-operator characteristic estimates were similar. Most data addressed
comparisons with perfusion scintigraphy (976 lesions, sensitivity 75%, specificity 77%), and
some data were also available for dobutamine stress echocardiography (273 lesions,
sensitivity 82%, specificity 74%).
CONCLUSION :
FFR shows modest concordance MPI.
The prognostic implications of discordant FFR and imaging results need further study.
Am J Cardiol. 2007 Feb 15;99(4):450-6
CFR………..
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CFR is considered the “gold standard”
during the development and validation
of both coronary angiography and 201Tl
perfusion imaging in animal models.
Circulation. 1997;96:484-490.
………
ACC/AHA/SCAI position
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Strong correlations exist between MPI and FFR/CVR
method
SN
SP
PPV
accuracy
FFR
<0.75
88
100
100
93
CVR
<2
92
95
90
93
January 3, 2006 issue of Circulation,
Where is the “discordance” come from ?
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It is the easiest way to explain the
difference….. rather than going through
The difficulty in correlating those two
tests with clinical picture of the pt to
understand the status of his CAD.
D.Berman......
Perfusion defects and non-obstructive coronary artery disease. Prevalence of
abnormal vasomotion and relation to atherosclerotic burden
20%
70%
10%
Important concept…..
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Not every anatomical significant lesion is
functionally significant ….
AND
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NOT every functionally significant perfusion
defect is essentially due to anatomical
significant lesion.
Functional
Anatomical
ischemia
significant CAD.
Very unlikely to miss
functionally sig. lesion
Rarely .
Viability
No
Not operator dependent
(interpretation)
V.Operator dependent
(interpretation)
Lower risk
More radiation…
Less expensive
10X risky
Depend on the procedure…
More expensive
What is your question ???
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Anatomy
Functional
significance
Prognosis
Correlates best with MPI
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a lumen area </=4 mm2
a lesion % area stenosis 60%
a lesion % plaque burden >/=75%.
Circulation 1999;100:250 –255.
Causes of “disagreement”
between cath and nuclear ?
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Not done at the same time.
Nuclear test microcirculation.
Nuclear test endothelial dys.
The lesion it self : spasm, thrombus, collaterals ,
interobserver variability, diffuse disease (IVUS)
Incomplete C.A study.
Refferal bias.
Attenuation artifact.
Ignoring your Bayesian analysis
Pt is not well prepared according to ASNC
guidelines:coffee,meds,small heart ,elderly
females….
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correlation is much better between
MPI/CFR than with coronary
angiography .
Chest 2003,124(4):1266
Remember : 80%
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80% pts admitted for ACS there was a concordance between MPI
and coronary angiography,when both studies were indicated to
select the most appropriate therapeutic modality.
In the 20% of discordant cases the attending physician decided on
a conservative strategy in most cases, as no significant enough
perfusion defect was shown on MPI in spite of severe CAD.
Rev Esp Cardiol. 1994 Dec;47(12):796-802
What does that mean if pts with (+) cath
and (-)MPI ?
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Pts with normal MPI and known CAD if treated medically they
have good prognosis.
..Not the other way around !!
Am j cardiol 1994;74:769-771
Prognostic value of normal Ex. sestamibi in patients with angiographic
significant CAD
METHODS:
We retrospectively investigated 90 consecutive patients who had a normal
exercise sestamibi but angiographic significant CAD. A group of 69
consecutive patients with both normal exercise Tc-sestamibi myocardial
SPECT and coronary arteries were included as control.
Nucl Med Commun. 2006 Apr;27(4):333-8
RESULTS:
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1.During a mean follow-up of 50+/-19 months, a total of 3 hard cardiac events (non-fatal
MI) / 7 soft cardiac events (late revascularization) were observed.
2.The annual hard cardiac event rate between the two groups was not significantly different
(0.6% vs. 0.3%, chi=0.47, P=NS)
3.the annual soft cardiac event rate was higher in patients with angiographic sig.CAD
(1.9% vs. 0, chi=5.74, P=0.02).
4. the annual hard cardiac events rate in patients with angiographic sig. CAD who were
treated medically was also not significantly different from that of the control group (0.8%
vs. 0.3%, chi=0.77, P=NS)
5.Among patients with angiographic sig. CAD, the annual hard cardiac event rate was not
statistically different between those treated medically and those who underwent
revascularization (0.8% vs. 0, chi=0.53, P=NS)
Nucl Med Commun. 2006 Apr;27(4):333-8
CONCLUSION
the data demonstrate that normal exercise sestamibi despite angiographic sig. CAD
suggests a low rate of cardiac death or non-fatal myocardial infarction but a
relatively high rate of late revascularization during an intermediate term of
follow-up.
Nucl Med Commun. 2006 Apr;27(4):333-8
HERE IS THE TROUBLE
CATH
+
Ivus.
Resolved Thrombus.
Spasm
+
?
Endothelial dysfunction
Microcirculation
Refferal bias
MPI
-
Indicate good prognosis
Functionally not significant lesion
Collaterals
Interobserver variability.
Time difference
Refferal bias
?
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So, what will happen if the
interventional cardiologist didn’t listen
to “Nuclear” ?
Listen to this…………
60yrs
 Male
 HPN,^cholestrol
 Typical angina sep 10
 Admitted 11th sep with ACS :
-ve enzymes/ECG
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Had MPI in the 13 sep ????
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On the 3rd october had cath
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the cath study ……
How did the pci go ?
Why LAD was stented ??
What do you think about pressure wiring or
IVUS the Cx?
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YES
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NO
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On the 27th oct he
had the second
MPI.
Helloooooo !!!!?
How big is the magnitude of this
problem in clinical practice?
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It quite large since nearly 90% of
lesions undergoing angioplasty have a
diameter stenosis <70% .
Circulation. 1997;96:484-490
% of the patients undergoes PCI , without definite evidence that the
coronary stenosis is causing their symptoms?
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70 %
Take home messages….
1.…Instead of asking your self
why the nuclear study is wrong? …
...You should be asking (why it’s right ?)
The Second:
2. normal C.A # normal coronary arteries.
The third:
3.Long term study of discordant FFR
vs.MPI on hard events.