Transcript Pro’s and Pitfalls in Cardiac Imaging

Pro’s and Pitfalls in
Cardiac Imaging
Resources
• Stress echo
– Douglas et al, JACC; 2007; 50: 187-204
• Stress nuclear
– Brindis et al, JACC 2005; 46: 1587-605
– Tool to calculate appropriateness:
http://www.skyscape.com/download/reseller.asp?format=binary&os=
win&device=pc&product=spectmpi
Iglehart JK, NEJM 2009;360:1030
It’s
a
Big
Deal
The 3 Worst Reasons For the
Recent Growth in Imaging
Use
• Defensive medicine
• Self-referral
• Inappropriate indications
What is An Appropriate Imaging Study?
An appropriate imaging study is one in which the
expected incremental information, combined with
clinical judgment, exceeds the expected negative
consequences* by a sufficiently wide margin for a
specific indication that the procedure is generally
considered acceptable care and a reasonable
approach for the indication.
*Negative consequences include the risks of the
procedure (i.e., radiation or contrast exposure) and
the downstream impact of poor test performance
such as delay in diagnosis (false negatives) or
inappropriate diagnosis (false positives).
Modern Cardiac Imaging Facts
• Extremely powerful in revealing non-invasive
information
– Anatomy, patho-physiology
– Therapeutic relevance to treatment
• Highly inter-disciplinary
– Many stakeholders
• Very costly
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–
–
–
Capital investment
Running costs
Sophisticated manpower
Complex interaction between “players”
Sequential Bayesian analysis of CAD probability using MPI.
Loong C Y , Anagnostopoulos C Heart 2004;90:v2-v9
©2004 by BMJ Publishing Group Ltd and British Cardiovascular Society
Pre- test Likelihood of CAD based upon age,
sex, and symptoms
Pro’s and Pitfalls in Cardiac
Imaging
First Rule of Testing:
Never order a test
if you do not know what to do
with the results
Effect of Screening on Clinical Outcomes
Gibbons, R. J. et al. J Am Coll Cardiol 2010;55:483-495
Copyright ©2010 American College of Cardiology Foundation. Restrictions may apply.
Technologies That Will Be
Discussed
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•
•
•
•
CXR (briefly)
Nuclear Studies
Echocardiography
Computerized Tomography
Magnetic Resonance
Imaging/Angiography
CXR
• Chest Pain—
– rule out dissection
– pneumothorax
– hemothorax
– pneumonia
– chamber dimensions
– effusions
– pulmonary vascularity
– coronary aneurysm
• Cough/Dyspnea/Fever with sxs
• Cancer screening “forget it”
• Ordering and not following up
“missed mass”
Gamma Camera
Role of Nuclear Cardiac Imaging
• Diagnosis of coronary artery disease,
• Evaluation of cardiac function
abnormalities,
• Monitoring of patients under treatment for
established cardiac disease.
• Verification of the diagnosis of acute
myocardial infarction
Up to 20% of nuclear stress tests
are false positives!*******
• Maybe we should re-name it “unclear”
medicine
– Most cardiologists do!!
• Inferior wall defects are especially
common due to the overlap of the
diaphragm with the heart muscle, yielding
the appearance of reduced blood flow.
• Anterior defects are common in females
with large breasts for the same
*******These
numbers
under
reasons……..as
well as
manyare
men!
study environments in peer reviewed
interpretations
ECG Gated SPECT imaging
(MUGA: multi gated acquisition)
• Simultaneous assessment of perfusion
and function in a single injection, single
acquisition sequence.
• Tc-99m permits evaluation of regional
myocardial wall motion and wall thickening
throughout the cardiac cycle
• Quantitates LV volume and EF
Indications for Pharmacologic
Nuclear Perfusion Stress Imaging
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Inability to perform adequate exercise
Left bundle branch block
Ventricular pacemaker
CCB’s or Beta blockers
Evaluation of patients very early after
acute MI (<3 days) or very early after
stenting (<2 weeks)
Nuclear Imaging and Chest Pain
Asymptomatic
Nuclear Imaging
• Out comes data is good. Large area of
ischemia, multiple ischemic locations, poor
LV function, Lung uptake - bad prognosis
• Established for peri-operative ?? need
• Too sensitive for non-life threatening CAD
• High radiation exposure
• $$$$$$
Heart Scan CT calcium score
Calcium Scoring
If you know you are at high risk – How will a scan change
outcomes?
Heart Scan CT calcium score
• If you want to do more angiograms
promote CT Ca Score
• No outcome data but may add a little to
Framingham
• Treat risk factors regardless of Ca
• Insurance will pay in Texas
• Radiation is likely greater risk than
benefit—radiation is lower than CTA or
nuke, however
CT Angiogram
Asymptomatic
If you know you are at high risk – How will a scan change
outcomes?
CHD Dissection PE - Good
Symptomatic CAD
Prognostic Value of Coronary CTA
Gibbons, R. J. et al. J Am Coll Cardiol 2010;55:483-495
Copyright ©2010 American College of Cardiology Foundation. Restrictions may apply.
CT Angiography
• Less invasive than cath—technology has
outpaced our knowledge as to how to use
it
• Radiation is high
• Renal failure and contrast nephropathy
similar to Coronary Angiography
• If need intervention radiation and contrast
is doubled
• $$$$$$$$$
CMR appropriate use
CMR appropriate use
CMR appropriate use
Magnetic resonance imaging
• Public Health Advisory: Risk of Burns
during MRI Scans from Transdermal
Drug Patches with Metallic Backings
• Pacemakers, Defibrillators
• Tattoos (myth busters)
• Gadolinium nephrogenic systemic fibrosis
(NSF) in renal insufficiency
Should I worry about radiation
associated with medical testing?
17 CXR
309
CXR’s
200 CXR’s
CT calcium score
20 – 262 CXR’s median 57 CXR’s
Approximate radiation exposure
309 CXR’s 51 mamograms
1 CXR
ECG
Echo
MRI
CXR
CT CA sc
Cor
Angio
CT Cor Angio
Nuclear
15%
1987
YOUR CHILDREN
SHOULD PLAN
TO BE
HEMOTOLOGY/
ONCOLOGY
DOCTORS!!!
48%
2006
Echocardiography
Echo
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Echo is safe – no radiation
Information can change therapy
Good correlate to physical exam
Outcome data is good - sudden death,
CAD prognosis, Heart failure prognosis
• It will do more in the future
• It is such a good test the government will
make reimbursement zero $’s and hope
you use the test anyway at your cost.
Types of Echo
• Transthoracic
• Transesophageal
• Stress- exercise and
Dobutamine
2and
3- D
Echo assessment
Allows the assessment of:
• Left ventricular size and function, including
regional wall motion abnormalities
• Right ventricular size and function
• Atrial abnormalities
• The heart valves – Mitral, Aortic, Tricuspid and
Pulmonary (stenosis, regurgitation etc)
• Intracardiac pressures
• Lung pressures
http://www.asecho.org
Indications for Echo
• MI/Chest pain
• Murmurs
• Heart Failure—right
and left/systolic AND
diastolic
• Pericardial
Diseases/Effusion
• Endocarditis /
Myocarditis
• Aortic diseases
• Pulmonary
Hypertension
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•
•
Dysrhythmias
Syncope
Dyspnea
Congenital Heart
Disease
Chemotherapy
Toxicity
Stroke
Shock
Hypertension
Tumors/Masses
Stress Echo
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Similar appropriateness to RNI
No radiation risk
Less sensitive but more specific
Technical limitation (patient, site,
interpreters)
• $$ cheaper and getting cheaper
• Review on inappropriate use
CLASSIFICATION OF APPROPRIATENESS
IN A LARGE ACADEMIC CARDIOLOGY PRACTICE
SPECT
ECHO
11.0%
9.0%
Appropriate
Uncertain
Inappropriate
Unclassified
14.0%
11.0%
64.0%
n=284
18.0%
9.0%
64.0%
n=298
Gibbons et al, 2008
JACC 51: 1283-9
Inappropriate Imaging Indications
Stress Echo and Nuclear
• Asymptomatic, low risk
• Pre-op, intermediate risk surgery
able to exercise
• Symptomatic, low pre-test probability,
able to exercise
• Pre-op, low risk surgery
Mayo Clinic, Gibbons et al, 2008
JACC 51:1283-89.
48%
17%
13%
10%
Conclusion
• Radiation is a serious threat
• We’re likely ordering too many imaging
studies
– Use the appropriateness criteria from the
ACC/AHA
• Never order a test unless you have a
plan for the results
A CHEERFUL HEART IS GOOD
MEDICINE– PROVERBS 17:22