Non-Invasive physiological assessment of coronary circulatory function
1. Non-Invasive physiological assessment of coronary
circulatory function
Presenter
Dr Praveen Gupta
Moderator
Dr Santhosh Satheesh
JIPMER
Pondicherry
India
04.01.2018
1
2. Introduction
Classification of CAD into one, two, and three vessels simple and not free of limitations
Plotnick remarked decisions based on the number of vessels is unidimensional approach to a
multidimensional problem, and demanded less anatomy and more physiologyin IHD
Topol and Nissen warned in 1995 of the excessive concern of cardiologists for coronary
luminology
2
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
3. Noninvasive Methods For The Physiological
Assessment Of Coronary Circulation
PET
SPECT: Single-photon emission computed tomography
Stress Echocardiography
Contrast echocardiography
Cardiac MRI
CT
PET-CT
Electrocardiographic exercise stress test
3
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
4. PET
Combines high spatial resolution (down to secondary or tertiary coronary branches) with
quantitative measures of rest and stress myocardial perfusion in absolute units to compute
absolute CFR
Quantitative measures correlated with low-flow thresholds causing ischemia.
Only noninvasive technique that allows quantitative assessment
Uses isotopes with a very short mean life (min/s)
High energy (511 KeV)
Tissue attenuation is minimal
Isotopes used are 13N-ammonium & 82Rb
4
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
6. PET
Highly complex
Expensive
Use is strictly limited
6
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
7. SPECT
Use for assessment of myocardial perfusion in clinical practice
Using thallium chloride (201TlCl) as the radiomarker
Thallium-201 is a monovalent cation of behavior similar to potassium
Penetrates the cell by active uptake (Na pump) and passive diffusion
Myocardial uptake is proportional to coronary flow and peaks at approximately20 min.
7
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
8. SPECT
Once peak value is reached, redistribution
takes place, by which intra and
extracellular concentrations balance &
201Tl circulates from high-uptake to low-
uptake zones.
Post-stress study must be acquired quickly
(within 10 min of radiomarker
administration) and before redistribution
begins
8
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
9. Other agent for SPECT
Despite the excellent myocardial extraction and flow kinetic properties of 201Tl, its energy spectrum
of 80 keV is suboptimal for conventional gamma cameras (ideal photopeak in the 140-keV range).
In addition, the long physical half-life of 201Tl (73 hours) limits the amount of 201Tl that may be
administered to stay within acceptable radiation exposure parameters.
99mTc-labeled tracers improve on these two limitations of 201Tl.
Although three 99mTc-labeled tracers—sestamibi, teboroxime, and tetrofosmin—have received U.S.
Food and Drug Administration (FDA) approval for detection of CAD, only sestamibi and
tetrofosmin are available for clinical use at present
Penetrate the cell by passive diffusion
No redistribution.
Administered in two doses ( stress study and at rest study)
99mTc emits 140 keV of photon energy and has a physical half-life of 6 hours
9
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
10. SPECT
Effort stress test using a treadmill or bicycle, or pharmacological stress: dipyridamole,
adenosine and dobutamine
In health, images, post-stress or at rest shows homogeneous activity in the LV myocardium
Any zone of hypoactivity must be considered pathological
Sensitivity and specificity 90-95%
10
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
11. 11
Figure 3. Cardiac perfusion SPECT study at stress (first and third rows) and rest (second and forth rows) shows
reversible perfusion defect in the anterolateral wall (arrows) consistent with myocardial ischemia. The perfusion
study has been corrected for attenuation by using maps computed from low-dose CT scans. The color convention
used shows normal perfusion in brighter colors and decreased perfusion in darker colors.
12. Diagnosis of multivessel disease
Reversible perfusion defects in more than one coronary region
Transitory ischemic left ventricular dilation and
Post-effort pulmonary radionuclide uptake
12
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
13. Gated-SPECT
Synchronizing onset of R-wave in the
ECG and dividing cardiac cycle into 8 or
16 segments
Simultaneous assessment of coronary
perfusion and cardiac function
Helps to differentiate defects due to
artifacts from those due to ischemia, as
well as the myocardial contractile reserve
by means of low-dose dobutamine
stimulation. 13
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
14. Role of SPECT
Very useful in patients with chronic coronary arterial disease
Cases in which the significance of a certain coronary stenosis is inconclusive it is useful
Correlates well with CFVR, relative CFVR, FFR, and diastolic FFR
In 85% of cases coincides with the severity of the disease and in decision making
For the diagnosis of the culprit lesion is approximately 84%
RCA (91%) ,LAD (79%) LCX (62%)
14
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
15. Limitation
Does not allow absolute quantification of the coronary flow,
Tell only about the most hypoperfused region with respect to the least hypoperfused
Non-atherosclerotic causes that can give rise to perfusion defects: the X syndrome, coronary
spasm, coronary ectasia, coronary fistula, and hypertrophic cardiomyopathies
15
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
16. Discordant cases
Ischemia to the territory of the right coronary or circumflex
Three-vessel disease with stenosis of similar severity
Totally occluded artery
16
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
17. Echocardiography for the diagnosis of myocardial ischemia
Very sensitive for the diagnosis of acute ischemia
For the diagnosis of myocardial viability
Low cost, Broad availability, absence of radiation, and can see any valve dysfunction
Main limitation, difficulty of making a quantitative analysis
New techniques like Doppler tissue studies strain and M-mode help in quantitative analysis
Broad interobserver variability
17
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
18. Concept of stress ECHO
Concept of the ischemic cascade
In the presence of ischemia, in first place disturbances in myocardial perfusion occur
Then, disturbances in diastolic function appear
Eventually, disturbances in systolic function
Finally, ECG disturbances and angina appear
18
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
19. Stress echocardiography
Exercise, dobutamine, &electrical stimulation increase myocardial oxygen demand
Bicycle and treadmill techniques used successfully, safe and well tolerated
Bicycle advantage to image throughout exercise
Bicycle technique more sensitive, whereas treadmill exercise more specific
Vasodilator drugs like dipyridamole and adenosine produce ischemia by coronary
theft mechanisms
19
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
25. Interpretation of stress echocardiography
Analyzed based on a subjective assessment of regional wall motion
Comparing wall thickening and endocardial excursion at baseline and during stress
The rest or baseline echocardiogram is first examined for the presence of global systolic
dysfunction or regional wall motion abnormalities
Normal response is hyperdynamic wall motion
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26. Interpretation of stress echocardiography
Normal response to stress includes decrease in end-systolic and end-diastolic volume
Lack of hyperkinesis is abnormal and caused by myocardial ischemia
Failure of the end-systolic size to decrease is an abnormal response
Increase in volume with stress indicates severe and extensive (i.e., multivessel) disease
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27. Stress ECHO
Sensitivity of 80% and specificity of 85-90%, close to that of radionuclide studies
Limitations are the need for special training, inability to walk and failure to attain an adequate
tachycardia
27
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
28. Assessment of the coronary reserve
Coronary reserve represents the capacity of the coronary arteriolar bed to dilate in response to
increased cardiac metabolic needs.
It is calculated as the ratio between the velocity of coronary flow after the administration of a
vasodilator (usually adenosine or dipyridamole) and in baseline circumstances
Coronary reserve decreases progressively when a fixed lesion produces a stenosis of 50%, in
such a way that it is completely suppressed with lesions of more than 90%
28
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
29. Assessment of the coronary reserve
TEE allows the visualization of the proximal segments of coronary arteries and through the
distal portion of the anterior descending artery
Allowing the coronary reserve to be calculated at that level
Distal coronary reserve is excellent because the reserve calculated reflects the residual
vasodilator capacity of the vascular bed, which is affected specifically by proximal lesions of
the proximal and middle anterior descending coronary
29
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
30. Assessment of the coronary reserve
Sensitivity of 91% and specificity of 76% for detecting stenosis >75%.
Flow signal was optimal without contrast in 55% and in all after contrast was administered
Reduced in left ventricular hypertrophy, small-vessel disease, constrictive
pericarditis,cardiomyopathies,transplanted hearts, and left bundle-branch block
30
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
31. Myocardia perfusion echocardiography
Used With vasodilators
Detection of ischemia by revealing a
heterogeneous flow
Contrast agents used intravenously
Contrast agents produce bubbles that enter
the coronary circulation and expand and
compress when exposed to ultrasound.
31
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
32. Myocardial perfusion echocardiography
Detection of bubbles depends on capacity to generate two resonance waves of different
frequency, in contrast with myocardial tissue
Ultrasound destroys the bubbles, if mechanical index is high
The bubbles can be destroyed by the fleeting emission of ultrasounds, but in the meantime
new bubbles that can be detected enter the system
Numerous problems mainly to artifacts
32
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
33. Myocardial contrast-enhanced echocardiography: schematic demonstrating the approach to myocardial perfusion imaging during steady-state infusion
of a contrast agent. A high–mechanical index impulse (MI) destroys all the intramyocardial bubbles to yield an unenhanced image that will serve as the reference
baseline. Subsequently, bubbles will return to and progressively enhance the myocardium until a steady-state concentration is reached. This may be monitored by
either a triggered approach in which imaging is performed on end-systolic images at increasing numbers of beats after the flash (1, 2, 3, 4, etc.) or by using low–
mechanical index continuous imaging. Enhancement will increase until a steady-state level is achieved (in this hypothetic example at a five-beat pulsing interval or
after 4 seconds of low-MI imaging). The rate at which replenishment occurs and the degree of enhancement under steady-state conditions, as can be quantitated
by video intensity, reflect myocardial perfusion. LV = left ventricle; RV = right ventricle. (Modified from Wei K, Jayaweera AR, Firoozan S, et al: Quantification of
myocardial blood flow with ultrasound-induced destruction of microbubbles administered as a constant venous infusion. Circulation 97:473, 1998.) 33
34. Myocardial perfusion echocardiography
Agreement between techniques was greater in the territory of the anterior descending artery
and right coronary , and significantly smaller in the territory of the circumflex artery
This is due to the large number of false defects obtained with echocontrast on the lateral face.
In effect, due to the angle of incidence of ultrasound on the lateral wall, false defects may be
more common in this territory.
34
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
35. Myocardial perfusion echocardiography
Good sensitivity 80-95%, lower specificity (50-75%)
Can also evaluate the non-reflow phenomenon
35
Candell-Riera J, Martín-Comín J, Escaned J, Peteiro J. Physiologic evaluation of coronary circulation. Role of
invasive and noninvasive techniques. Revista Española de Cardiología. 2002 Mar 1;55(03):271-91.
36. Cardiac MRI
CMR perfusion imaging examines the first-pass transit of an intravenous bolus of GBCA
Uses Fast bright blood gradient-echo in MRI during the injection of GBCA bolus
Gadolinium provides strong signal enhancement in well-perfused regions, compared with
hypoenhancement (dark regions) in poorly perfused myocardium
Provide information of blood flow at the endocardial/ epicardial or at a segmental level
36
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
37. CMR imaging of ischemia and infarct extent in a 59-year-old obese man with dyspnea on exertion. A, First-pass
resting perfusion image reveals a severe defect in the inferolateral wall (arrow). B, Late gadolinium enhancement
demonstrates two foci of previously unrecognized infarcted myocardium (arrows). Subsequent coronary angiography
revealed severe stenoses in the left circumflex and right coronary arteries. Images of ischemia and infarction can be
superimposed and compared qualitatively and quantitatively.
37
38. Typical pattern of microvascular obstruction in a patient with ST-elevation myocardial infarction
due to an occluded left anterior descending artery, treated with primary percutanous coronary
intervention (A) Demonstrates first pass perfusion images with hypoperfusion of the
anteroseptum, especially at day 2 and week 1 postmyocardial infarction. (B) Demonstrates late
gadolinium-enhanced images with the dark signal at the subendocardium at each time point
representing regions of microvascular obstruction.
38
39. Cardiac MPI
Pharmacologic stress CMR myocardial perfusion imaging (MPI) for used in CAD
Combined perfusion, LGE, and cine CMR data yield the highest sensitivity and specificity
Not limited by attenuation artifacts
Free from ionizing radiation
Three- to four-fold higher spatial resolution than SPECT
Sensitivity 91% & specificity of 94% for functionally significant stenosis defined by FFR
39
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
41. Qualitative interpretation of cardiac MRI perfusion imaging.Top row shows adenosine stress images, while
the bottom row shows rest images. Left column: basal left ventricle; middle column: mid left ventricle; right
column: apical left ventricle. The white arrows point to a large perfusion defect in the anterolateral, infero-
lateral, inferior and infero-septal wall, extending from the basal to the apical slice. 41
42. Cardiac MRI
A stress CMR study takes 35 to 45 minutes (compared with 2 hours for SPECT)
CMR MPI also can characterize the dynamic range of myocardial blood flow without being
limited by plateau effect of counts at high flow rates as seen in some nuclear tracers
CMR MPI performed better than SPECT in detecting coronary stenosis especially in the
group of Patient with multivessel stenosis
42
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
43. Cardiac MRI
Negative CMR MPI have annualized cardiac event rates of less than 1%.
CMR MPI provide effective risk assessment in women
CMR often provides clinicians with alternative diagnoses in patients suspected to have CAD
CMR MPI can be analyzed quantitatively using the signal intensity versus time curves
measured from myocardial segments.
Common semiquantitative parameters include signal upslope (rate of rise of the ascending
curve), upslope integral (area under the upslope), and contrast enhancement ratio (ratio of
peak to baseline signal intensity).
43
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
44. Cardiac MRI
Fully quantitative analysis of CMR perfusion yields absolute myocardial blood flow (in
milliliters per minute per gram of tissue) using deconvolution methods and modeled
compartmental analysis.
Quantitative analyses have potential advantages including minimization of reader’s bias and
enhanced detection of abnormality in cases of balanced perfusion reduction or inadequate
vasodilation
44
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
45. Dobutamine Stress Cardiac MRI
Excellent sensitivity (83% to 86%) and specificity (83% to 86%)
Provides strong prognostic value in risk assessment of patients
Addition of stress myocardial perfusion and myocardial strain encoding during dobutamine
stress can be a helpful adjunct to cine CMR in detecting myocardial ischemia
Accelerated real-time cine CMR imaging, eliminates breath-holding or ECG gating during
dobutamine stress testing, yielded encouraging results
Treadmill exercise CMR is investigational currently but has been shown to be feasible in
highly experienced centers
45
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
46. 46
Figure 3
Three examples of CMR, SPECT, and angiographic findings
(A) Stress perfusion CMR shows inducible hypoperfusion (ischaemia) in the septum and anterior wall (arrow shows dark area of hypoperfusion), SPECT is concordant (arrows show lower signal
counts during stress), indicating anteroseptal inducible ischaemia, and angiography confirms a stenosis (arrow) in the left anterior descending artery. (B) Late gadolinium-enhanced CMR (arrow
shows hyperenhancement in the inferior wall) and SPECT (fixed defect; arrows show comparable inferior defect at rest and stress) are concordant, showing a transmural inferior myocardial
infarct with the corresponding right coronary artery chronic total occlusion (arrow) seen at angiography. (C) Late gadolinium-enhanced CMR shows subendocardial inferior infarction (arrow),
SPECT was reported as normal (no wall motion abnormality), and the angiogram shows coronary atheroma but no clinically significant stenosis (or occlusion). As per study protocol, CMR in this
patient was classified as a false positive, showing the potential limitations of angiography as a reference test for the detection of coronary heart disease. The case also shows that SPECT can miss
small subendocardial infarcts. CMR=cardiovascular magnetic resonance. SPECT=single-photon emission computed tomography
Greenwood JP, Maredia N, Younger JF, Brown JM, Nixon J, Everett CC, Bijsterveld P, Ridgway JP, Radjenovic A, Dickinson CJ, Ball SG. Cardiovascular magnetic resonance and single-photon
emission computed tomography for diagnosis of coronary heart disease (CE-MARC): a prospective trial. The Lancet. 2012 Feb 10;379(9814):453-60.
47. Cardiac Computed Tomography
Myocardial attenuation reflects relative coronary blood flow on first pass imaging
First-pass CT stress perfusion imaging is being developed
Imaging protocol includes contrast-enhanced CT angiography both at rest and during the
administration of adenosine agonists
Most commonly using 320-slice CT or 128-slice dual-source CT
Sensitivity 72% to 98%, and specificity 71% to 92%
Primary limitation radiation exposure
47
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
48. Cardiac computed Tomography
Computational FFR from resting coronary CT angiographic images
Measured from standard first-pass coronary CT angiography
Overall accuracy was limited at 73%, with sensitivity of 90% and specificity of 54%.
Advantage of assessment from routine coronary CT angiograms acquired at rest
48
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
49. CT fractional flow reserve (FFR) using computational fluid dynamics. From the invasive coronary angiogram (A), coronary
lesions assessed by invasive FFR (B) are correlated with CT-derived FFR (C). (From Nakazato R, Park HB, Berman DS, et al:
Non-invasive fractional flow reserve derived from CT angiography (FFRCT) for coronary lesions of intermediate stenosis
severity: Results from the DeFACTO study. Circ Cardiovasc Imaging 6:881, 2013.)
49
Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular
Medicine. Elsevier Health Sciences; 2015.
52. Conclusions
Non invasive assessment has important role
Do not treat stenosis
Treat both stenosis and physiology
Cardiac MRI and PET-CT are new imaging modality
Use Stress ECHO as much as possible
We first done MBBS then MD then DM so similarly we are family physician then
general physician and then interventional cardiologist
Intervention has a role but use it very judiciously because it has its long term
complication and cost
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