the role of spect mpi in the evaluation of coronary artery...
TRANSCRIPT
Gregg Furie, HMS IVGillian Lieberman, MD
The Role of SPECT MPI in the Evaluation of Coronary Artery Disease
Gregg Furie, HMS IVGillian Lieberman, MD
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT MPI
SPECT•
single-photon emission computed tomography
MPI•
myocardial perfusion imaging
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Gregg Furie, HMS IVGillian Lieberman, MD
Goals
•
Basic principles of SPECT MPI•
Interpretation of SPECT MPI•
Correlate with anatomy and pathophysiology
•
Clinical utility of SPECT MPI in patients with or without known CAD
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Gregg Furie, HMS IVGillian Lieberman, MD
Patient PB
•
History•
75 yo
woman with hypertension and hyperlipidemia
presents with chest pain and dyspnea
on exertion •
Strong family history of CAD
•
No history of obesity, smoking, diabetes•
Goals for workup of CAD•
Diagnosis
•
Risk stratification•
Management
Gregg Furie, HMS IVGillian Lieberman, MD
What studies are available to evaluate PB, a patient with an intermediate to high
pre-test probability of CAD?
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Gregg Furie, HMS IVGillian Lieberman, MD
Modalities for Evaluation of CADFunctional Studies•
Non-invasive•
Exercise tolerance testing•
Stress echocardiography•
Stress SPECT MPI•
Stress PET•
MRI
Anatomical Studies•
Invasive•
Coronary angiography•
IVUS •
Non-invasive•
EBCT•
MSCT•
MRA
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT MPI was chosen as the initial study in PB’s
workup for CAD. Why?
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Gregg Furie, HMS IVGillian Lieberman, MD
Functional Studies•
Assessment of hemodynamic consequences of CAD•
Perfusion defects•
Left ventricular dysfunction
•
Non-invasive •
Well validated •
ETT•
Stress echocardiography•
SPECT MPI
•
Widely available•
Useful for diagnosis, risk stratification, and guiding management
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Gregg Furie, HMS IVGillian Lieberman, MD
Anatomical Studies•
Visualization of coronary vasculature and stenoses
•
Inform decisions regarding method of intervention•
Only well validated and widely available modality (coronary angiography) is invasive •
Associated morbidity and mortality
•
Gold-standard for diagnosis of CAD •
Coronary angiography
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT MPI versus other Functional Studies
•
Good test characteristics in diagnosis of CAD•
Better than ETT•
Roughly equivalent to stress echocardiography
•
Can be used in patients with baseline ECG abnormalities•
Not operator dependent
•
Validated role in risk stratification for patients with CAD•
Cost-effective
•
Widely available•
Detection of early events in ischemic cascade
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Gregg Furie, HMS IVGillian Lieberman, MD
The Ischemic Cascade
modified from Heart. 2005; 91: 1110-1117
SPECT MPI
Echocardiography
ETT
Gregg Furie, HMS IVGillian Lieberman, MD
How does SPECT MPI detect ischemia due to CAD?
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT: Basic Principles•
Nuclear imaging study
•
Gamma particles detected by a rotating camera•
Radionuclides•
Thallium201
•
Long half life (73 hours) → low doses•
Low energy emitter → increased attenuation•
Low doses and high attenuation → low resolution•
Technetium99m
•
Short half life (6 hours) → high doses•
High energy emitter → decreased attenuation•
High doses and low attenuation → high resolution
www.gehealthcare.com
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Gregg Furie, HMS IVGillian Lieberman, MD
MPI: Basic Principles•
Radionuclides
taken up by perfused
myocytes
•
Tl201: active transport across membrane by Na+/K+
ATPase•
Tc99m
sestamibi
and Tc99m
tetrofosmin: passive diffusion across cell and mitochondrial membranes
•
Identify areas of infarction or inducible ischemia by comparing perfusion in rest and stress states
•
Exercise or pharmacologically induced coronary artery vasodilation
→ proportionately less perfusion distal to
stenoses
→ relatively low radionuclide uptake in myocardium distal to stenoses
→ relatively low signal
from areas of low perfusion
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Gregg Furie, HMS IVGillian Lieberman, MD
Impaired Coronary Flow Reserve Causes Decreased Perfusion Distal to Stenoses
http://merck.micromedex.com/index
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT MPI Protocols•
Exercise vs. pharmacological•
Exercise: Bruce protocol•
Patients who can achieve ≥85% of maximal predicted heart rate•
Exercise preferable since exercise capacity, symptoms, and ST segment changes provide additional prognostic information
•
Pharmacological•
Vasodilators: adenosine, dipyridamole•
Iono-/chronotrope: dobutamine•
ECG gated vs. nongated•
Gated protocol allows determination of LV function•
Single isotope vs. double isotope •
Rest and stress portions performed back-to-back in double isotope
•
Visual, semi-quantitative, or quantitative interpretation
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Gregg Furie, HMS IVGillian Lieberman, MD
Cardiac Anatomy in SPECT MPI
http://info.med.yale.edu/intmed/cardio/imaging/techniques/spect_anatomy/index.html
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Gregg Furie, HMS IVGillian Lieberman, MD
Coronary Artery Territories
from Hurst’s The Heart http://brighamrad.harvard.edu/education/online/Cardiac/
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Gregg Furie, HMS IVGillian Lieberman, MD
Patterns of Ischemia in Various Coronary Artery Territories in SPECT MPI
from Hurst’s The Heart from Hurst’s The Heart
Single-vessel disease Multi-vessel diseaseA
LSI
S LA
I
SA VLA HLA
SA VLA HLA
I: inferior wallS: septum
A: anterior wallL: lateral wall
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Gregg Furie, HMS IVGillian Lieberman, MD
High Risk Features on SPECT MPI•
Perfusion defects in multiple vascular territories
•
Extensive hypoperfusion
in one vascular territory•
LVEF < 40%
•
Increased end-systolic and end-diastolic volumes •
Transient LV cavity dilation during stress
•
Increased Tl201
lung uptake
image courtesy of Dr. Kevin Donohoe
stress
rest
cavitary
dilation
Gregg Furie, HMS IVGillian Lieberman, MD
How is SPECT MPI used clinically for evaluation of CAD?
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT MPI for Diagnosis of CAD•
Patient selection•
Patients with intermediate pre-test probability of CAD based on historical and clinical factors
•
Patients with intermediate to high likelihood of CAD based on ETT or indeterminate ETT
•
Patients with baseline ECG abnormalities
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Gregg Furie, HMS IVGillian Lieberman, MD
SPECT MPI for Risk Stratification in CAD
•
Identify patients with >1% likelihood of cardiac events•
Cardiac death •
Nonfatal MI•
Progression of CAD
•
Use risk stratification to guide management •
Patient selection•
Intermediate or high risk by Framingham/ATPIII score•
Patients with known CAD from prior cath
or SPECT MPI who have been asymptomatic for >2 years or are symptomatic
•
Patients with prior revascularization who have been asymptomatic for >5 years or are symptomatic
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Gregg Furie, HMS IVGillian Lieberman, MD
PB’s
SPECT MPI Study
•
Dual isotope exercise SPECT MPI study•
Performance
•
Exercised 4 minutes•
Achieved 87% of maximal predicted heart rate•
Study stopped due to dyspnea
•
No ECG changes•
Strongly positive study at low level of exercise
•
LVEF 50%
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Gregg Furie, HMS IVGillian Lieberman, MD
PB’s
Stress SPECT MPI Study: Apical Ischemia Consistent with LAD Stenosis
stress
restshort axis
horizontal long axis
vertical long axis
stress
rest
stress
restimages courtesy of Dr. Donohoe
spin to assess for artifact or attenuation
gated view of LV function
Gregg Furie, HMS IVGillian Lieberman, MD
What are the implications of PB’s SPECT MPI study?
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Gregg Furie, HMS IVGillian Lieberman, MD
Diagnostic Implications•
Test characteristics as compared to angiography•
Sensitivity
•
Exercise: 87%•
Vasodilator: 89%•
Specificity
•
Exercise: 73%•
Vasodilator: 75%•
Normalcy rate: 91%
•
Corrects for decreased specificity due to referral bias.•
People with positive studies are referred for coronary angiography while people with negative studies generally are not, thus increasing the apparent proportion of false positive SPECT MPI studies.
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Gregg Furie, HMS IVGillian Lieberman, MD
Prognostic Implications
•
Excellent negative predictive value•
0.5% annual cardiac event rate in patients with normal studies
•
Specific patient populations have worse prognosis for same degree of perfusion defect•
Advanced age•
Known CAD•
Diabetics•
Pharmacological stress tests
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Gregg Furie, HMS IVGillian Lieberman, MD
Severity of Perfusion Defect is Correlated with Likelihood of Future Cardiac Events
from Fuster
V et al. Hurst’s The Heart; Eleventh Edition. The McGraw-Hill Companies, Inc. 2004
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Gregg Furie, HMS IVGillian Lieberman, MD
Poststress
Ejection Fraction is Correlated with Survival
Ejection fraction ≥45% Ejection fraction <45%
from Fuster
V et al. Hurst’s The Heart; Eleventh Edition. The McGraw-Hill Companies, Inc. 2004
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Gregg Furie, HMS IVGillian Lieberman, MD
Implications for Management
•
Patients with no or mild ischemia benefit from medical management over revascularization
•
Patients with moderate to severe ischemia (>10% of myocardium) benefit from revascularization over medical management
•
Only patients with inducible ischemia benefit from revascularization
•
Selective referral of patients to catheterization is cost-effective
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Gregg Furie, HMS IVGillian Lieberman, MD
Implications of PB’s
SPECT MPI Study
•
Diagnosis•
High post-test probability of CAD
•
Risk Stratification•
>1% annual probability of a major cardiac event
•
Management•
Likely to benefit from revascularization
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Gregg Furie, HMS IVGillian Lieberman, MD
Companion Patient’s Coronary Angiogram
http://www.path.utah.edu/ http://www.path.utah.edu/
LAD
LCX
LCX
Stent
LAD
Complete occlusion of proximal LAD Stented
LAD
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Gregg Furie, HMS IVGillian Lieberman, MD
PB’s
Post-Stent Stress SPECT MPI Study: Resolution of Inducible Apical Ischemia
Before revascularization After revascularization
short axis
horizontal long axis
vertical long axis
stress
rest
stress
rest
stress
rest
short axis
horizontal long axis
vertical long axis
images courtesy of Dr. Kevin Donohoe
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Gregg Furie, HMS IVGillian Lieberman, MD
Conclusion
•
SPECT MPI identifies regions of myocardial ischemia with decreased perfusion and LV dysfunction
•
SPECT MPI has a well validated role in diagnosis and risk stratification in patients with CAD
•
Risk stratification with SPECT MPI can be used to cost- effectively guide management of patients with CAD
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Gregg Furie, HMS IVGillian Lieberman, MD
References
•
Brindis
RG, Douglas PS, Hendel
RC, Peterson ED, Wolk
MJ, Allen JM, Patel MR, Raskin
IE. ACCF/ASNC appropriateness criteria for single-photon emission computed tomography myocardial perfusion imaging
(SPECT MPI): a report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group and the American Society of Nuclear Cardiology. J Am Coll
Cardiol
2005;46:1587–
605.•
Clark AN and Beller
GA. The present role of nuclear cardiology in clinical practice. Q J Nucl Med Mol Imaging. 2005; 49: 43-58
•
Fuster
V et al. Hurst’s The Heart; Eleventh Edition. The McGraw-Hill Companies, Inc. 2004•
Klocke
FJ, Baird MG, Bateman TM, Berman DS, Carabello
BA, Cerqueira
MD, DeMaria
AN, Kennedy JW, Lorell
BH, Messer JV, O’Gara PT, Russell RO Jr, St. John Sutton MG, Udelson
JE, Verani
MS, Williams KA. ACC/AHA/ASNC guidelines for the clinical use of cardiac radionuclide imaging—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASNC Committee to Revise the 1995 Guidelines for the Clinical Use of RadionuclideImaging). Circulation. 2003;108:1404 –1418.
•
Loong
CY and Anagnostopolous
C. Diagnosis of coronary artery disease by radionuclide myocardial perfusion imaging. Heart. 2004; 90: 2-9
•
Mannting
F et al. Atlas of Myocardial Perfusion SPECT. http://brighamrad.harvard.edu/education/online/Cardiac/•
Micromedex. http://merck.micromedex.com/index•
Sabharwal
NK and Lahiri
A. Role of myocardial perfusion imaging for risk stratification in suspected or known coronary artery disease. Heart. 2003; 89:1291-1297
•
Schuijf
JD et al. Cardiac imaging in coronary artery disease: differing modalities. Heart. 2005; 91: 1110-1117•
University of Utah, Department of Pathology. http://www.path.utah.edu/•
Yale University School of Medicine. http://info.med.yale.edu/intmed/cardio/imaging/techniques/spect_anatomy/index.html
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Gregg Furie, HMS IVGillian Lieberman, MD
Acknowledgements
Dr. Kevin Donohoe
Dr. Gillian Lieberman
Pamela Lepkowski
Larry Barbaras