Assessment of myocardial viability

Assessment of
Myocardial Viability
PRESENTED BY : DR PAWAN KUMAR
MODERATOR : DR P J BHATTACHARYYA
DEPARTMENT OF CARDIOLOGY, GMCH, GUWAHATI.

Pathophysiology of Myocardial
Ischemia and Viability
• Imbalance between oxygen supply and demand results in
myocardial ischemia.
• If the imbalance is transient (i.e., triggered by exertion), it
represents reversible ischemia.
• However, if supply-demand imbalance is prolonged, high-
energy phosphates are depleted, and regional contractile
function progressively deteriorates.
• If the supply-demand balance is sufficiently prolonged, cell
membrane rupture with cell death follows.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294

• The myocardium has several mechanisms of acute and chronic
adaptation to a temporary or sustained reduction in coronary
blood flow , known as
• stunning,
• hibernation, and
• ischemic preconditioning .
• These responses to ischemia preserve sufficient energy to
protect the structural and functional integrity of the cardiac
myocyte.

Stunned myocardium
• is most often observed after a transient period of ischemia
followed by reperfusion (depressed function at rest but
preserved perfusion).
• Regional myocardial function remains depressed for up to 6 hours
after resolution of ischemia following a 15-minute occlusion in
the absence of tissue necrosis
• The ischemic episodes can be single or multiple, brief or
prolonged, but never severe enough to result in injury.
• This state is typically observed soon after coronary occlusion
and reperfusion in the setting of acute MI.

Hibernating myocardium
• refers to adaptive responses of the myocardium to repetitive
episodes of ischemia resulting in myocardial hypoperfusion at
rest (depressed function and perfusion at rest).
• In clinical practice, it is likely that the adaptive responses of
hibernation and stunning coexist.
• In stunned and hibernating myocardium, myocardial function
is depressed at rest, but myocytes remain viable.

Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 57 page 1092

• Requirements for cellular viability include
• (1) sufficient myocardial blood flow,
• (2) cell membrane integrity, and
• (3) preserved metabolic activity.
• Myocardial blood flow must be adequate to deliver substrate
to the myocyte for metabolic processes and to remove the
end products of metabolism.

• If Myocardial blood flow is severely reduced,
• metabolites accumulate,
• causing inhibition of the enzymes of the metabolic pathway,
• depletion of high-energy phosphates,
• cell membrane disruption, and
• cell death.
• Thus, with severe reduction in blood flow, perfusion tracers alone
provide information about myocardial viability or absence of
viability.

• However, in regions in which the Myocardial blood flow
reduction is less severe,
• perfusion information alone may be an insufficient signal to
• identify clinically relevant viability, and additional data, such as
metabolic indices, may be important.

• Because cell membrane integrity, another requisite for cell
survival, is dependent on preserved intracellular metabolic
activity to generate high-energy phosphates,
• tracers that reflect cation flux (e.g., 201Tl),
• electrochemical gradients (sestamibi or tetrofosmin), or
• metabolic processes (FDG)
• provide insight into myocardial viability

MajorMyocardialFuels and Energeticsin
Normaland IschemicMyocardium
• High-energy phosphates, such as adenosine triphosphate (ATP),
provide the fuel that powers the myocyte contractile proteins .
• ATP is generated in the myocardium by two different but integrated
metabolic processes: oxidative phosphorylation and glycolysis.
• Fatty acids, glucose, and lactate are the major sources of energy in
the heart, and depending on the arterial concentration of each and
the physiologic condition, any one of these three can be the
principal substrate.
• Increased uptake and use of one substrate will lead to a decreased
contribution by the others.

• In the fasting state,
• long-chain free fatty acids are the preferred source of energy in
the heart,
• with glucose accounting for only 15% to 20% of the total energy
supply.
• When the oxygen supply is normal, high levels of ATP and
tissue citrate formed by breakdown of fatty acids suppress the
oxidation of glucose.
• When the oxygen supply is decreased, ATP and citrate levels
fall, and the rate of glycolysis is accelerated.

• Anaerobic glycolysis can be maintained only if lactate and hydrogen
ion (the byproducts of glycolysis) are removed and do not
accumulate.
• In the setting of severe hypoperfusion, these end products of the
glycolytic pathway accumulate,
• causing inhibition of the glycolytic enzymes and depletion of high-
energy phosphates,
• resulting in cell membrane disruption and cell death.
• Thus, even to maintain anaerobic glycolysis, minimally sufficient
blood flow is necessary.

METHODS
1) echocardiography,
2) single-photon emission computed tomography (SPECT),
3) positron emission tomography (PET), and
4) cardiac magnetic resonance imaging (cardiac MRI)
5) Combined approach .

• Different non-invasive methods that assess viability tests
different facets which indicate that the “cell is alive”.
• Stress echo - contractile reserve
• SPECT - Thallium and technetium uptake indicates intact cell
membrane (thallium is a potassium analogs that relies on the
Na/K ATPase for uptake, technetium uptake relies on intact
mitochondrial membrane potential)
• PET - FDG-18 uptake indicates active glucose metabolism.
• MRI - delayed enhancement/ hyperenhancement-non viable
scarred tissue.
• stress MRI -tests contractile reserve.

1 Stress Echocardiography
• there are five techniques employed;
• dobutamine stress,
• myocardial contrast,
• 2d gray scale wall motion scoring,
• tissue doppler
• adenosine speckle tracking stress echocardiography.
• Resting echocardiography highlights diastolic wall thickness of
at least 5 mm as a marker of viable myocardium.
• the most commonly used criterion to identify viable
myocardium is by detection of contractile reserve.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014

stress echocardiography
• this is achieved by stress echocardiography using dobutamine,
Adenosine or dipyridamole.
• An infusion of low-dose dobutamine (5–10 mg/ kg/min) is
administered which results in increased contractile function of
viable segments whereas nonviable ones do not show such
response.
• Dobutamine infusion starts at 5 μg/kg per minute for 3
minutes and increases to 10 μg/kg per minute for an
additional 3 minutes.
• Myocardial viability can also be detected by using the biphasic
response

• With dobutamine infusion, it may demonstrate a
• (1) a lack of increase in baseline contractility suggesting myocardial
necrosis;
• (2) an increase in myocardial contractility suggesting myocardial
stunning or hibernation or
• (3) BIPHASIC RESPONSE at
• lower doses(5–10mg/kg/min)--an improvement in contractile
performance
• at higher doses (>15mg/kg/min)--Contractility regresses as the
metabolic demand stimulated overwhelms the tissue‘s capacity to
respond

contrast echocardiography
• using intravenous micro-bubble contrast, contrast
echocardiography is able to demonstrate viability qualitatively.
• these micro-bubbles are inert gases and stay in the vascular
space and behave like red blood cells in terms of rheology.
• segments that have normal or patchy perfusion are classified
as being viable in contrast to those with no perfusion who are
taken as non-viable.

• Myocardial contrast enhancement depends on an intact
microcirculation.
• Left ventricular opacification (LVO) obtained with microbubbles
improves the definition of the LV border.
• This provides better quantitation of LV volume by the Simpson
method.
• The correlation between LV volume measured with cardiac magnetic
resonance (CMR) and that measured with echocardiography is
better with the use of LVO.
• Regional wall motion analysis can also be better with LVO.

doppler echocardiography
• uses optimum increase in coronary flow reserve (CFR) as an
additional marker of viability.
• the underlying mechanism behind that is the increased
myocardial metabolic demand with stress, which causes
dilatation of the coronary vessels.

adenosine speckle tracking
• Additional information on myocardial viability can be obtained
from adenosine speckle tracking based myocardial strain
imaging.
• usually at rest, there is no significant difference between the
viable and nonviable myocardium strain.
• with adenosine stress, viable segments increase their
longitudinal strain in contrast to non-viable ones which remain
unchanged

Low Dose Dobutamine Stress
Echocardiography (LDDE)
• the most recent meta-analysis by schinkel AF et al (2007), of
33 studies (1121 patients);
• cumulative sensitivity and specificity of 81% and 78%
respectively,
• with a positive predictive value (ppV) and negative predictive
value (NpV) of 75% and 83% respectively, (p < 0.05).

Limitation and advantages
• The main limitations of echocardiography include;
• operator dependence, both in data acquisition, and interpretation,
however, this could easily be overcome by good training and
experience.
• Adequate acoustic window acquisition is another potential
limitation but has greatly improved by using contrast agents.
• The main advantages of stress echocardiography include;
• good validity,
• wide availability,
• cost effectiveness,
• lack of ionizing radiation, and
• being friendly with implanted devices.

Prognostic value
• The VIAMI-trial (2012), Viability-Guided Angioplasty After Acute Myocardial
Infarction was the first randomized control trial
• investigating a viability-guided invasive approach in
• 261 patients recruited
• at least 48 hours after an acute MI who then underwent LDDE for the
• detection of viability within 72 hours of MI.
• Those with a viable myocardium were randomized to an invasive or conservative
treatment.
• The primary endpoint was the composite of death from any cause, recurrent MI
and unstable angina at 1-year follow-up.
• An invasive approach in patients with a high viability score had a substantial
reduction in ischemic events.
• The VIAMI-trial supports the concept that viability determines prognosis.

2 SPECT
• The main technique involve the administration of a radioactive tracer
such as thallium-201 or Technetium Tc-99m, with Tc-99m sestamibi
being the most widely used in clinical practice.
• The most commonly used criterion to identify viable myocardium is the
percentage tracer uptake by the dysfunctional segments,
• where a tracer activity of >50% and
• redistribution of >10% are
• used as markers of viability as a consequence of preserved membrane
integrity (detected by thallium SPECT).
• A tracer activity of >50% and improvement in tracer uptake
• after nitrates administration is also taken as a markers of viability, as a
consequence of preserved mitochondrial function (detected by technetium
SPECT).

Principles of Assessing Myocardial
Viability by Radionuclide Techniques
• Quantitative analysis of tracer uptake correlates directly with the
magnitude of preservation of tissue viability, and
• For a dysfunctional segment or territory, the probability of functional
recovery after revascularization is related to the magnitude of tracer
uptake,
• representing the degree of preserved myocardial viability (extent of
hibernation or stunning) within that territory.
• A dysfunctional territory with normal or only mildly reduced tracer
uptake thus has a high likelihood of improved function after
revascularization.
• By contrast, a territory with a severe reduction in tracer uptake would
represent predominant infarction, and the likelihood of improved
function after revascularization would be low.

Relation between tracer uptake in a dysfunctional territory and the
subsequent probability of functional recovery after revascularization.

Imaging Protocols for Assessment of
• Thallium-201.
• The presence of 201Tl after redistribution implies preserved
myocyte cellular viability.
• Because the absence of 201Tl uptake on the redistribution images is
not a sufficient sign of the absence of regional viability
• After 201Tl reinjection, approximately 50% of regions with fixed
defects on stress-redistribution imaging show significant
enhancement of 201Tl uptake, predictive of improvement in
regional LV function.
• The presence of a severe 201Tl defect after reinjection identifies
areas with a very low probability of improvement in function.

Standard SPECT imaging display.
A, The short-axis images
represent a portion of the
anterior, lateral, inferior, and
septal walls.
B, Vertical long-axis images
represent the anterior wall,
apex, and inferior wall.
C, Horizontal long-axis images
represent the septum, apex, and
lateral walls.

INFARCT STRESSINDUCEDISCHAEMIA

• Various protocols have been developed to optimise the
information obtained from thallium-201 imaging such as;
• stress redistribution imaging,
• late redistribution imaging,
• thallium-201 re-injection and
• rest-redistribution imaging

201Tl stress redistribution
• The uptake of 201Tl is an energy-dependent process requiring
intact cell membrane integrity, and the presence of 201Tl
implies preserved myocyte cellular viability.
• Imaging is done-
• immediately following stress, with either exercise or
pharmacologically induced coronary hyperemia with
dipyridamole or adenosine, and
• after 3–4 hr redistribution of Tl-201

INTERPRETATION
• Defects on post-stress images, may fill in by the time the rest-
redistribution images are acquired, indicating viability.
• A defect that persists and appears again on the 3–4 hr images
• (i.e., a fixed-defect) may be due to:
(1) markedly reduced regional perfusion,
(2) impaired cellular membrane integrity, inadequate for the
active sequestration of the tracer into the cell,
(3) cell death (acute infarction), or
(4) scar tissue.
• Thus, fixed-defects on 3– 4 hr redistribution images may
represent only severely hypoperfused—and not necessarily
infarcted tissue

Late redistribution images
• Acquire a third set of images at 24-48 hours
• This would allow for redistribution of the tracer to very-
ischemic (yet viable) tissue
• It has been shown that 22% of fixed defects (at early
redistribution imaging) demonstrate normal Tl-201 uptake at
later redistribution.
• This may indicate a poorly perfused, yet viable region

• Late redistribution imaging, 24 to 48 hours after the initial
stress 201Tl injection, allows more time for redistribution to
occur and has good positive predictive value (PPV) for
improvement in function.
• Even with late redistribution imaging, the NPV is suboptimal,
because redistribution does not occur in some patients even
after a prolonged period, and in addition, image quality may
be poor.
• In such patients, 201Tl reinjection after late redistribution
imaging may provide further insight into defect reversibility
and thus viability.

201Tl reinjection
• This may be necessary because redistribution depends on the
continued delivery of the tracer over the 3–4 hr period.
• If the blood concentration of Tl- 201 decreases a great deal,
there may be insufficient delivery of the tracer and the defect may
not fill-in during redistribution imaging
• The second injection of thallium with delayed imaging after
this repeat injection will give the myocytes with reduced
perfusion the greatest opportunity to sequester thallium

Rest-redistribution 201Tl imaging
• With this, images are obtained 15 to 20 minutes after tracer
injection at rest, reflecting regional blood flow at rest, and
images obtained 3 to 4 hours after redistribution reflect
myocyte viability.
• The finding of a reversible resting defect may identify areas of
myocardial hibernation .
• This finding appears to be an insensitive but specific sign of
potential improvement in regional function.

Rest-redistribution imaging protocol
• Rizzllo V. et al (2005) analysis of 22 studies (557 patients) using
Tl-201 rest-redistribution showed an average sensitivity and
specificity of 88% (range 44-100%) and 59% (range 22-92%)
respectively, and PPV 69% and NPV of 80%, for predicting
regional function recovery

Thallium-201re-injection protocol
• Re-injection protocol is an extra value on top of rest-
redistribution results. Rizzllo V. et al (2005) found lower
specificity of 50% having analysed 11 studies (301 patients)
and sensitivity of 86%, with low PPV of 57% and NPV of 83%

99mTc Sestamibi and Tetrofosmin.
• The performance of the 99mTc agents in predicting improvement in
regional function after revascularization is similar to that of 201Tl.
• They do not share the redistribution properties of 201Tl
• The key finding to evaluate is the magnitude of tracer uptake in a
dysfunctional region.
• Normal uptake is consistent with preserved viability;
• only mild reduction in uptake is consistent with predominantly preserved
viability;
• moderate reduction in uptake is consistent with an admixture of viable and
infarcted tissue; and
• a severe defect is consistent with predominant infarct.
• Administration of nitrates to improve blood flow at rest before injection
of sestamibi appears to improve slightly the ability of these tracers to
detect myocardial viability

Technetium-99m sestamibi (MIBI)
• Rizzllo V. et al (2005) analysis of 20 studies (488 patients)
assessing Technetium-99m sestamibi studies, without the use
of nitrates concluded a lower sensitivity of 81%, but better
specificity of 66%, with PPV of 71% and NPV of 86%.

• The main limitations of SPECT include;
• higher cost compared to echocardiography,
• limited spatial resolution,
• potential difficulty in interpreting results in patients with
balanced myocardial ischemia (3-vessel disease) and the risk of
radiation.
• The main advantages include;
• extensive validation,
• increasing availability,
• good sensitivity and
• lower cost compared to PET.

Prognostic value
• Cardiac SPECT viability study results can predict the recovery
of global LV function;
• 99mTc-sestamibi demonstrated a sensitivity of 81% and
specificity of 60%,
• thallium re-injection a sensitivity of 86% and specificity of 47%,
• thallium rest redistribution a sensitivity of 90% and specificity of
54%.

3 PET
• MAGING OF GLUCOSE METABOLISM.
• Although fatty acids are the primary source of fuel in the fasting state,
• increased arterial glucose concentration in the fed state results in an increase in
insulin levels, stimulating glucose metabolism while inhibiting lipolysis.
• Fluorine-18 deoxyglucose (18-FDP), is the most validated radiotracer for cardiac
PET metabolism.
• The result is a switch in myocardial metabolism from predominant use of fatty
acids to glucose.
• The principle of using a metabolic tracer that tracks glycolysis is based on the
concept that glucose utilization may be preserved or increased relative to flow
in hypoperfused but viable (hibernating) myocardium, termed metabolism-
perfusion mismatch.
• Myocardial glucose use is absent in scarred or fibrotic tissue, represented by
metabolism-perfusion match.

PET Blood Flow–Metabolism Mismatch.
• The extent of the PET mismatch pattern (enhanced FDG
uptake relative to blood flow) (PERFUSION-FDG MISMATCH)
• correlates with improvement in LV function after
revascularization as well as with the clinical course, magnitude of
improvement in HF symptoms, and survival after
revascularization.
• Patients with HF and an extensive PET match pattern
(PERFUSION-FDG MATCH) (diminished blood flow and severe
reduction in FDG uptake),
• representing predominant infarction, are unlikely to benefit
clinically from revascularization.

PATTERNS OF PERFUSION: 18F-FDG
IMAGES
• Normal perfusion and normal FDG or “normal match” of
healthy subjects or patients with low EF caused by nonischemic
cardiomyopathy (A)
• Abnormal perfusion and abnormal FDG or “abnormal match” of
myocardial scar (B)
• Abnormal perfusion and normal 18F-FDG or “abnormal mismatch”
of hibernating myocardium in the distal half of the LV (C)
• Normal perfusion and low FDG uptake or “reverse mismatch” of
adequately perfused myocardium metabolizing fatty acids rather
than glucose (D)

PET
• The recent analysis by Schinkel AF et al (2007) of 24 studies involving
756 patients noted weighted mean sensitivities and specificities of
92% and 63%, and positive and negative predictive values of 74%
and 87% respectively.
• Prognostic value
• A meta-analysis by Beanlands et al (1998) of 10 studies involving
1046 patients, found that,
• the mortality rate was higher in those who did not undergo
revascularization despite a PET scan confirming significant myocardial
viability.
• The annual death rate was 4% in those that had revascularization
versus 17% in those who did not undergo revascularization.

• The main limitations of PET include its
• high cost,
• limited availability, and
• the use of radio-active tracers.
• The main advantages include;
• established validity and
• excellent sensitivity.
• Compared with the SPECT, PET has better spatial and
temporal resolution, with better quality pictures and less
radiation.

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 Cardiac Radionuclide Imaging)
( Circulation. 2003;108:1404–1418.)

4 Cardiovascular Magnetic
Resonance Imaging - CMR
• Three main techniques employed when using CMR in
assessing myocardial viability are;
• delayed enhancement (DE), known as late-gadolinium
enhancement (LGE),
• dobutamine stress (DS) and
• end-diastolic wall thickness (EDWT)

CardiovascularMagneticResonance
Imaging
• CMR imaging offers a multicomponent assessment of structure and
physiology to evaluate myocardial viability.
• From early cine CMR studies,
• end-diastolic wall thickness of 5.5 mm or more and
• dobutamine-induced systolic wall thickening of 2 mm or more
• have excellent sensitivity and specificity in the prediction of
segmental contractile recovery after revascularization.
• In addition, the transmural extent of myocardial scar detected by
LGE imaging accurately depicts a progressive stepwise decrease in
functional recovery despite successful coronary revascularization,
especially in myocardial regions of akinesia or dyskinesia.

Cardiovascular Magnetic Resonance
Imaging {CMR}
• DE/LGE techniques demonstrate the status of myocardial perfusion
and tissue enhancement by i.v. administration of gadolinium-
chelated contrast.
• After 5min of contrast agent, T1-weighted images are acquired
which show regions of myocardial infarction exhibiting high signal
intensity i.e. high contrast enhancement.
• This hyperenhancment is related to the interstitial space between
collagen fibers, which is larger in scar tissue/non viable myocardium,
than in normal viable myocardium.
• This allows the determination of the extent of transmural disease,
which in turn correlates inversely with the likelihood of functional
recovery of the myocardium following revascularization.

Extent transmurality of LGE is the gold
standard technique for viability
assessment by CMR.
LGE with a cutoff of less than 50%
transmurality of scar tissue had a high
sensitivity and a high negative predictive
value to predict functional recovery.

AKINETIC SEGMENT
NO SCAR ON MRI
VIABLE
SEGMENT
BECAME FUNCTIONAL
POST
REVASCULARISATION
REVERSIBLE
DYSFUNCTION

AKINETIC SEGMENT
SCAR ON MRI
NON VIABLE
SCAR AND
AKINESIS WAS
PERSISTENT POST
REVASCULARISATION
IRREVERSIBLE
DYSFUNCTION

• A meta-analysis by Romero et al (2012), included 24
prospective trials in 698 patients; 11 studies assessing DE, 9
DS and 4 EDWT.
• DE demonstrated the highest sensitivity of 95% with
specificity of 51%, PPV of 69% and NPP of 90% in detecting
viable myocardium.
• The respective values for DS were 81%, 91%, 93% and 75%.

• The main limitations of CMR include;
• high cost,
• long study time,
• the requirement for breath-holding sequences and restrictions in patients
with implant devices and impaired renal function.
• However, advances in MRI technology are holding promises to reduce
imaging time, increase spatial resolution and adapt to scan implanted
devices.
• The main advantages of CMR include
• excellent anatomical details using steady state free precision (SSFP) cine
sequences in EDWT,
• good sensitivity/specificity with good interobserver/intraobserver agreement
in DE imaging, and
• excellent sensitivity offered with DS.

Prognostic value
• Gerber et al (2012) included 144 patients with ischemic LV
dysfunction who had undergone DE imaging,
• then either received revascularization with PCI or CABG or
were managed conservatively
• demonstrated good prediction of survival, which was
significantly lower in patients who did not undergo
revascularization.
• Furthermore, it has been suggested that by combining CMR
with nuclear imaging additional benefits are obtained.

Comparison of Imaging Techniques
for Viability Assessment.
• dobutamine echocardiography appears to be slightly more
specific, and
• PET techniques appear to have better accuracy.
• For patients with more severe LV dysfunction, in whom
thinner myocardial walls are often present, an advantage of
PET and CMR is their better spatial resolution for imaging
thinner objects.

• On the other hand, low-dose dobutamine cine imaging
provides a highly specific physiologic assessment of the
• midmyocardial and subepicardial contractile reserve and early
after acute MI, when tissue edema is prominent.
• Contrast-enhanced CMR in combination with low-dose
dobutamine stimulation seems to be the most accurate
method, with a growing body of evidence to support it.

Conclusion
• The recommended approach to assess myocardial viability begins
with either
• dobutamine echocardiogphy or
• radionuclide myocardial perfusion imaging,
• depending upon availability and local expertise.
• Despite cardiac magnetic resonance (CMR) and positron emission
tomography (PET) scanning have greater sensitivity they may be
more challenging to perform and not as widely available.
• Dobutamine stress echocardiography is the most widely used
method for assessing myocardial viability

• The best data on the clinical impact of myocardial viability assessment comes from a meta-
analysis and from two randomised trials;
• The Surgical Treatment for Ischemic Heart Failure (STICH) trial and The Canadian PPAR
study.
• The meta-analysis of 24 observational studies by Allman et al of 3088 patients,
demonstrated that revascularization compared to medical therapy,
• in patients with heart failure and myocardial viability have a significantly better survival
compared to patients with no viability who did poorly irrespective of therapy.
• However, perhaps contrary to expectation, both The STICH trial and The Canadian PPAR
study reported a lack of association between the presence or absence of residual
myocardial viability in patients mortality outcome when treatment was allocated
(revascularization vs medical therapy).
• Several limitations with potentially confounding effects may explain the seemingly opposing
results, and further trials are necessary to explore this outcome.

• In a meta-analysis of outcome studies after viability imaging,
patients with evidence of preserved myocardial viability
• who underwent revascularization had a substantial reduction
in the risk of cardiac death during long-term follow-up
compared with those treated medically .
• current HF guidelines consider revascularization as a class IIa
indication (level of evidence B) to improve survival in patients
with mild to moderate LV systolic dysfunction and significant
multivessel CAD or proximal LAD stenosis when viable
myocardium is present.

• Finally,
• it is important to note the European Society of Cardiology (ESC), the
European Association for Cardio- Thoracic Surgery (EACTS), and
American College of Cardiology/ American Heart Association
guidelines for
• revasculirazation of heart failure still recommend viability testing
as a part of diagnostic work up.

TAKE HOMEMESSAGE
Markers of Viable Myocardium

Assessment of myocardial viability

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