Left ventricular function Left ventricular function evaluation of patients evaluation of patients with ischemic with ischemic cardiomyopathy.cardiomyopathy.

ByByMostafa Sayed MostafaMostafa Sayed Mostafa

Prof. of Nuclear MedicineProf. of Nuclear MedicineAssiut University-Egypt.Assiut University-Egypt.

Many forms of cardiomyopathy exist, Many forms of cardiomyopathy exist, but by far the most common but by far the most common category is category is dilated cardiomyopathy.dilated cardiomyopathy.

The most common cause of dilated The most common cause of dilated cardiomyopathy is cardiomyopathy is extensive extensive coronary artery diseasecoronary artery disease(Jay,2001).(Jay,2001).

Coronary artery diseaseCoronary artery disease (CAD) (CAD) results in results in an inadequate blood supply to the heart an inadequate blood supply to the heart muscle, which leads to injury and death of muscle, which leads to injury and death of heart muscle. As a result, the heart cannot heart muscle. As a result, the heart cannot pump as forcefully. The dead heart muscle pump as forcefully. The dead heart muscle is finally replaced by fibrous tissue.is finally replaced by fibrous tissue.

The remaining uninjured heart muscle then The remaining uninjured heart muscle then stretches and thickens to compensate for stretches and thickens to compensate for the lost pumping action. the lost pumping action.

The more the heart muscle is stretched, the The more the heart muscle is stretched, the more forcefully it contracts or pumps but more forcefully it contracts or pumps but only up to a point. After that point, the only up to a point. After that point, the stretching and thickening do not stretching and thickening do not adequately compensate, and dilated adequately compensate, and dilated cardiomyopathy with heart failure cardiomyopathy with heart failure developsdevelops( Michael etal.,2001).( Michael etal.,2001).

An An ischemic dilated cardiomyopathyischemic dilated cardiomyopathy is is present when myocardial infarction of present when myocardial infarction of left ventricle experiences remodeling left ventricle experiences remodeling and a drop in ejection fraction occurs .and a drop in ejection fraction occurs .

Dilatation of the LV and a decrease in Dilatation of the LV and a decrease in ejection fraction (EF) ejection fraction (EF) occurs in 15-40% occurs in 15-40% of subjects within 12-24 monthsof subjects within 12-24 months following an anterior MI and in a following an anterior MI and in a smaller percentage of subjects smaller percentage of subjects following an inferior MIfollowing an inferior MI( Michael ( Michael etal.,2001).etal.,2001).

It is now well established that impaired It is now well established that impaired left ventricular function does not left ventricular function does not necessarily represent irreversible necessarily represent irreversible tissue injury, because contractile tissue injury, because contractile performance can improve after performance can improve after revascularization .revascularization .

So ,assessment of left ventricular So ,assessment of left ventricular function must couple with function must couple with assessment of residual viable assessment of residual viable myocardium myocardium (Christoph et al., (Christoph et al., 2002).2002).

Various imaging techniques, including Single Various imaging techniques, including Single photon emission computed tomography photon emission computed tomography (SPECT), (SPECT), positron emission tomographypositron emission tomography (PET) echocardiography(PET) echocardiography, and magnetic , and magnetic resonance imaging resonance imaging (MRI),(MRI), have been mostly have been mostly employed to determine and localize the employed to determine and localize the extent of irreversible myocardial injury. extent of irreversible myocardial injury.

Many of these techniques are affected by a Many of these techniques are affected by a number of limitations. These include number of limitations. These include difficulties in detecting small infarcts, difficulties in detecting small infarcts, inability to separate infracted from inability to separate infracted from dysfunctional but viable myocardium, and dysfunctional but viable myocardium, and relatively poor spatial resolution relatively poor spatial resolution (Gibbson (Gibbson et al.,2000).et al.,2000).

Radionuclide techniques Radionuclide techniques used in evaluation of left used in evaluation of left ventricular functionventricular function

(A) Multigated study (MUGA)(A) Multigated study (MUGA)

(B) Myocardial perfusion (B) Myocardial perfusion scintigraphyscintigraphy

(C) Gated cardiac SPECT(C) Gated cardiac SPECT

(D) Positron Emission Tomography (D) Positron Emission Tomography

(A) Multigated study (A) Multigated study (MUGA):(MUGA):Conventionally, ventricular function is Conventionally, ventricular function is

evaluated by multigated acquisition evaluated by multigated acquisition studies (MUGA) with either Tc-99m-labeled studies (MUGA) with either Tc-99m-labeled red blood cells or human serum albumin. red blood cells or human serum albumin.

Gating is the technique that links the Gating is the technique that links the acquisition of the image data to the acquisition of the image data to the cardiac cycle, the ECG is the most cardiac cycle, the ECG is the most convenient and is universally used. convenient and is universally used.

The accuracy of the gate depends on the The accuracy of the gate depends on the QRS complex recognition scheme used by QRS complex recognition scheme used by the computer and the qualities of the ECG the computer and the qualities of the ECG signal signal (Sugihara et al., 2001).(Sugihara et al., 2001).

(B)(B) Myocardial perfusion Myocardial perfusion scintigraphyscintigraphy Usually employed for the evaluation of muscle Usually employed for the evaluation of muscle

cell viability, using tracers that are markers of cell viability, using tracers that are markers of perfusion. Study of the myocardial distribution perfusion. Study of the myocardial distribution of the radiopharmaceutical of the radiopharmaceutical after stress and at after stress and at restrest provides information on myocardial provides information on myocardial viability and inducible perfusion abnormalities. viability and inducible perfusion abnormalities.

SPECT imaging is preferred over planar imaging SPECT imaging is preferred over planar imaging because of the three dimensional nature of the because of the three dimensional nature of the images and their superior contrast resolution images and their superior contrast resolution (Anagnostopoulos(Anagnostopoulos et al., 2004).et al., 2004).

Thallium-201Thallium-201 is the common is the common radiopharmaceutical used to assess radiopharmaceutical used to assess viability and perfusion abnormalities, viability and perfusion abnormalities, initially distributed after intravenous initially distributed after intravenous injection to the myocardium injection to the myocardium according to myocardial viability and according to myocardial viability and perfusion. perfusion.

Technetium-99m MIBITechnetium-99m MIBI and and Tc-99m Tc-99m tetrofosmintetrofosmin have been used for have been used for myocardial perfusion imaging myocardial perfusion imaging especially with SPECT studies especially with SPECT studies (Anagnostopoulos et al., 2004).(Anagnostopoulos et al., 2004).

The role of The role of stress myocardial perfusion stress myocardial perfusion imagingimaging techniques in the functional techniques in the functional evaluation of ischemic cardiomyopathy evaluation of ischemic cardiomyopathy is to assess the presence of myocardial is to assess the presence of myocardial viability in patients with significant viability in patients with significant systolic dysfunction and to determine systolic dysfunction and to determine the extent of CAD as well as infarct-the extent of CAD as well as infarct-related area.related area.

TI-201 stress-redistribution SPECT study show, TI-201 stress-redistribution SPECT study show, stress induced cardiac dilatation, irreversible stress induced cardiac dilatation, irreversible perfusion defects at most of Lt. ventricular wall.perfusion defects at most of Lt. ventricular wall.

(C) Gated cardiac SPECT:(C) Gated cardiac SPECT:

Gated myocardial perfusion single photon Gated myocardial perfusion single photon emission computed tomography emission computed tomography (g SPECT)(g SPECT) has been used to assess myocardial has been used to assess myocardial perfusion and left ventricular function and perfusion and left ventricular function and volumes through one study. volumes through one study.

Technetium-99m MIBITechnetium-99m MIBI and tetrofosmin, after and tetrofosmin, after intravenous injection are distributed within intravenous injection are distributed within the myocardium according to myocardial the myocardium according to myocardial perfusion and permit perfusion and permit ECG gatingECG gating, which , which gives additional functional information gives additional functional information (Anagnostopoulos(Anagnostopoulos et al., 2004).et al., 2004).

The most The most important informationimportant information provided by provided by gated myocardial perfusion tomography g gated myocardial perfusion tomography g SPECT (which can be done with stress and SPECT (which can be done with stress and rest) includes the following:rest) includes the following:

1) 1) LVEFLVEF, which can be performed serially to , which can be performed serially to monitor cardiac function; monitor cardiac function;

2) 2) Wall motion impairmentWall motion impairment, which usually , which usually correlates with regional myocardial correlates with regional myocardial damage;damage;

3) 3) Volume of the ventricleVolume of the ventricle; and overall ; and overall quality of contractions ;quality of contractions ;

4) 4) Pulmonary activityPulmonary activity (Andrewet al.,2000).(Andrewet al.,2000).

(1)value of left ventricular ejection fraction(LVEF):

If wide regional dysfunction is present, global left ventricular ejection fraction can be markedly depressed which is the most frequently calculated quantitative parameter of ventricular function.

Gated SPECT, unaffected by attenuation or chamber overlap, is more accurate than planar imaging.

During exercise, a normal increase for During exercise, a normal increase for LVEF has been accepted to be LVEF has been accepted to be 5%5% or or more over a normal resting value .more over a normal resting value .

In patients with LV dysfunction the In patients with LV dysfunction the recent data have shown that stress recent data have shown that stress radionuclide-determined LVEF of radionuclide-determined LVEF of 40%40% carry possibility of mortality in range carry possibility of mortality in range of 5% in 1-2 years, while LVEF less of 5% in 1-2 years, while LVEF less than than 30 %30 % carry mortality rate about carry mortality rate about 25 % in 1-2 years25 % in 1-2 years (Gordon et al., (Gordon et al., 2001)2001)

In patients with left ventricular ejection In patients with left ventricular ejection fractions (LVEF's) below 30% and fractions (LVEF's) below 30% and predominant heart failure symptoms, predominant heart failure symptoms, coronary revascularizationcoronary revascularization can improve LV can improve LV function, heart failure symptoms, and long-function, heart failure symptoms, and long-term prognosis when compared with medical term prognosis when compared with medical treatment alone. treatment alone.

Because post-operative improvement in LVEF Because post-operative improvement in LVEF has been related to the preoperative has been related to the preoperative identification of viable myocardial tissue, identification of viable myocardial tissue, viability is a crucial factorviability is a crucial factor when considering when considering chronic ischemic heart failure patients for chronic ischemic heart failure patients for coronary artery bypass grafting. coronary artery bypass grafting.

(2)(2) Wall motion analysis:Wall motion analysis:

One of the principal clinical applications of One of the principal clinical applications of g SPECT was the evaluation of regional g SPECT was the evaluation of regional ventricular function and wall motion ventricular function and wall motion abnormalities. abnormalities.

Multislice cine displays have proven Multislice cine displays have proven highly effective and readily demonstrate highly effective and readily demonstrate the diagnostic efficacy of g SPECT the diagnostic efficacy of g SPECT imaging in comparison to contrast imaging in comparison to contrast ventriculography and planar blood pool ventriculography and planar blood pool imaging. imaging.

The left ventricle is subdivided anatomically The left ventricle is subdivided anatomically into multiple segments according to into multiple segments according to standard definitions. standard definitions.

Each segment is graded on four point scale :Each segment is graded on four point scale :1) 1) normalnormal, , 2) 2) hypokinesiahypokinesia ,abnormal areas ,abnormal areas

demonstrating diminished contraction ,demonstrating diminished contraction ,3) 3) akinesiaakinesia ,complete absence of wall ,complete absence of wall

motion , motion , 4) 4) dyskinesiadyskinesia , a dyskinetic wall segment is , a dyskinetic wall segment is

one that passively bulges outward while one that passively bulges outward while the surrounding ventricular segments the surrounding ventricular segments contract inward. contract inward.

(3)(3) Left ventricular volume:Left ventricular volume:

It is anIt is an importantimportant determinant of determinant of diagnosis and prognosis in patients diagnosis and prognosis in patients with heart disease. with heart disease.

In patients with old myocardial In patients with old myocardial infarction, the left ventricular mass infarction, the left ventricular mass index was significantly lower, and the index was significantly lower, and the magnitude was closely related to the magnitude was closely related to the severity of the perfusion defect on severity of the perfusion defect on the resting SPECT images.the resting SPECT images.

The evaluation of the chamber size The evaluation of the chamber size difference between stress and rest difference between stress and rest images is of great importance .images is of great importance .

Scintigraphic evidence of Scintigraphic evidence of left left ventricular dilatation with stressventricular dilatation with stress is an is an indirect indicator of extensive indirect indicator of extensive coronary artery disease .coronary artery disease .

There is a strong correlation There is a strong correlation (sensitivity 60%, specificity 95%) (sensitivity 60%, specificity 95%) between LV stress dilatation and the between LV stress dilatation and the presence of multivessel CAD. presence of multivessel CAD. (Patrick et al., 2003).(Patrick et al., 2003).

Gated Tc-99m MIBI myocardial perfusion SPECT Gated Tc-99m MIBI myocardial perfusion SPECT shows diminished perfusion, wall thickness, LVEF shows diminished perfusion, wall thickness, LVEF and impaired wall motion and impaired wall motion (From Noor Eldeeen et (From Noor Eldeeen et

al.,2003).al.,2003).

(4)(4) Pulmonary activity on stress imaging:Pulmonary activity on stress imaging:

An increase in Tc99m MIBI lung uptake on An increase in Tc99m MIBI lung uptake on stress imaging is a marker for severe stress imaging is a marker for severe underlying coronary artery disease. A lung underlying coronary artery disease. A lung to heart ratio of to heart ratio of greater thangreater than 33%33% is is suggestive of underlying severe CAD suggestive of underlying severe CAD (Choy (Choy & Leslie 2001).& Leslie 2001).

In thallium-201 myocardial perfusion imaging, In thallium-201 myocardial perfusion imaging, abnormally high lung uptake due to abnormally high lung uptake due to prolonged lung transit time and increased prolonged lung transit time and increased capillary wedge pressure correlates with left capillary wedge pressure correlates with left ventricular dysfunction at exercise and ventricular dysfunction at exercise and usually usually indicates multivessel CADindicates multivessel CAD and and identifies patients identifies patients withwith poor prognosispoor prognosis (Saber et al.,1997).(Saber et al.,1997).

Positron Emission Tomography Positron Emission Tomography (PET):(PET):

PET is known to accurately identify viable PET is known to accurately identify viable myocardium in patients with CAD. myocardium in patients with CAD.

It can be performed with ECG gating. It can be performed with ECG gating. The pharmacological stress imaging can also The pharmacological stress imaging can also

be done. be done. Compared with SPECT, Compared with SPECT, PET offersPET offers high high

sensitivity, superior resolution, possibilities sensitivity, superior resolution, possibilities of attenuation correction and allows absolute of attenuation correction and allows absolute quantification of regional tracer uptake. quantification of regional tracer uptake.

But on the other hand, But on the other hand, PET has not been used PET has not been used on a wide scaleon a wide scale due to the limited availability due to the limited availability of PET system and difficulties in the of PET system and difficulties in the production of its tracers. production of its tracers.

Segments with reduced perfusion in SPECT Segments with reduced perfusion in SPECT studies but preserved FDG uptake in PET studies but preserved FDG uptake in PET study (study (Perfusion-FDG mismatchPerfusion-FDG mismatch) are ) are classified as viable.classified as viable.

The extent of mismatch as assessed by PET The extent of mismatch as assessed by PET correlates closely with improvement of correlates closely with improvement of global LV function after revascularization . global LV function after revascularization .

On contrast, segments with proportionate On contrast, segments with proportionate reduction in perfusion and FDG uptake reduction in perfusion and FDG uptake ((Perfusion-FDG matchPerfusion-FDG match) are considered as ) are considered as non viable tissue and frequently do not non viable tissue and frequently do not show improved ventricular function show improved ventricular function following revascularization following revascularization (George et al(George et al 2000).2000).

Using FDG PET has been demonstrating that Using FDG PET has been demonstrating that 36-47% of myocardium36-47% of myocardium with irreversible with irreversible perfusion defects according to both TI-201 perfusion defects according to both TI-201 stress-redistribution and Tc99m MIBI stress-redistribution and Tc99m MIBI stress-rest imaging, stress-rest imaging, are metabolically are metabolically activeactive and hence viable , so can benefit and hence viable , so can benefit from revascularization surgery.from revascularization surgery.

Because the resolution of FDG PET is much Because the resolution of FDG PET is much higher than that of g SPECT , using higher than that of g SPECT , using gated gated FDG PETFDG PET provides a more sensitive and provides a more sensitive and accurate method for the calculation of left accurate method for the calculation of left ventricular ejection fraction (LVEF) and ventricular ejection fraction (LVEF) and wall motion abnormalities in patients with wall motion abnormalities in patients with ischemic heart disease ischemic heart disease (Yoshinaga et (Yoshinaga et al.,2002). al.,2002).

Another approach employs quantitative Another approach employs quantitative estimates of regional estimates of regional myocardial myocardial glucose utilizationglucose utilization as a predictor of LV as a predictor of LV function. function.

A threshold value of A threshold value of 0.25 u mol/min/gm0.25 u mol/min/gm has been proposed to distinguish has been proposed to distinguish between reversibility and irreversibility between reversibility and irreversibility of regional LV function after of regional LV function after revascularization. Use of this threshold revascularization. Use of this threshold in a study offered a sensitivity of 99% in a study offered a sensitivity of 99% for predicting an improvement in LV for predicting an improvement in LV function function (Bax et al.,2001).(Bax et al.,2001).

Rubidium perfusion and FDG PET viability study. Rubidium perfusion and FDG PET viability study. Rubidium images (top row) performed with Rubidium images (top row) performed with dobutamine stress , show a perfusion defect in the dobutamine stress , show a perfusion defect in the apex and lateral wall (arrows). FDG images apex and lateral wall (arrows). FDG images (bottom row) show normal metabolism in those (bottom row) show normal metabolism in those regions (open arrows) indicating myocardial regions (open arrows) indicating myocardial

viability. (From Andrew et al ., 2000.)viability. (From Andrew et al ., 2000.)

ECHOCARDIOGRAPHYECHOCARDIOGRAPHY In ischemic heart diseasesIn ischemic heart diseases

echocardiography echocardiography is indicated to:is indicated to:

– – detect deterioration of left ventricular detect deterioration of left ventricular function;function;

– – follow the behavior of left ventricular follow the behavior of left ventricular expansion, show aneurysm formation expansion, show aneurysm formation and thrombus after institution of and thrombus after institution of therapy;therapy;

– – detect reversible ischemia by stress detect reversible ischemia by stress echocardiography.echocardiography.

The echocardiographic The echocardiographic hallmark of ischemichallmark of ischemic heartheart disease is regional loss of systolic disease is regional loss of systolic wall thickening and motion abnormalities.wall thickening and motion abnormalities.

The geometry of the left ventricle in patients The geometry of the left ventricle in patients with cardiomyopathy is often sub-optimal with cardiomyopathy is often sub-optimal for 2-dimensional ultrasound when for 2-dimensional ultrasound when assessing left ventricular (LV) function and assessing left ventricular (LV) function and localized abnormalities such as a localized abnormalities such as a ventricular aneurysm. ventricular aneurysm.

So, some investigators prefer using of real-So, some investigators prefer using of real-time 3-D echocardiography for evaluating time 3-D echocardiography for evaluating patients with cardiomyopathypatients with cardiomyopathy (Shiota et (Shiota et al., 1999).al., 1999).

Dobutamine stress echocardiographyDobutamine stress echocardiography assesses the ability of myocardium to assesses the ability of myocardium to increase its contraction in response to an increase its contraction in response to an adrenergic stimulus. adrenergic stimulus.

It has been routinely employed for evaluation It has been routinely employed for evaluation of patients with ischemic heart disease by of patients with ischemic heart disease by means of means of detection of wall motion detection of wall motion abnormalitiesabnormalities under pharmacologic stress. under pharmacologic stress.

Evaluation of Evaluation of wall thickeningwall thickening by echo during by echo during low-dose dobutamine infusion can also be low-dose dobutamine infusion can also be used to used to determine reversible left ventricular determine reversible left ventricular dysfunctiondysfunction in patients with ischemic heart in patients with ischemic heart disease (disease (Scott et al.,2001). Scott et al.,2001).

Magnetic Resonance Magnetic Resonance ImagingImaging

Recently, MRI has demonstrated its potential Recently, MRI has demonstrated its potential forfor showing showing the structure , the function of the structure , the function of the heart muscles, the thickness of the the heart muscles, the thickness of the chambers, and determine the extend of chambers, and determine the extend of damage caused by a heart attack or damage caused by a heart attack or progressive heart disease. progressive heart disease.

MRI, creates images of the beating heart that MRI, creates images of the beating heart that can be used to diagnose a variety of can be used to diagnose a variety of cardiovascular problems. Depending on how cardiovascular problems. Depending on how many images are needed, the exam will many images are needed, the exam will generally take from 15 to 45 minutes generally take from 15 to 45 minutes (Radiology Info, 2003).(Radiology Info, 2003).

Cardiac magnetic resonance imaging Cardiac magnetic resonance imaging (CMRI) has been performed early as (CMRI) has been performed early as non gated images, and then non gated images, and then gatedgated cardiac study was introduced using cardiac study was introduced using chest ECG leads.chest ECG leads.

The images acquired during the The images acquired during the multiple phases of the cardiac cycle multiple phases of the cardiac cycle can be viewed in a cine loop, thereby can be viewed in a cine loop, thereby displaying the contracting heart displaying the contracting heart (William & Bradley2003).(William & Bradley2003).

Dobutamine stress CMRIDobutamine stress CMRI assesses the assesses the induction of ischemia by evaluation of induction of ischemia by evaluation of regional wall motion during progressively regional wall motion during progressively increased doses of IV dobutamine. increased doses of IV dobutamine.

Ischemic cardiomyopathyIschemic cardiomyopathy can be evaluated can be evaluated on the basis of perfusion or wall motion on the basis of perfusion or wall motion abnormalities, comparing rest and stress abnormalities, comparing rest and stress imaging. Normal myocardium is bright, imaging. Normal myocardium is bright, and nonperfused myocardium is dark. and nonperfused myocardium is dark.

Ischemia results in a new or worsening wall Ischemia results in a new or worsening wall motion abnormality compared with the motion abnormality compared with the baseline study.baseline study.

A new technique known as “A new technique known as “delayed hyper delayed hyper enhancementenhancement” is proving to be extremely ” is proving to be extremely sensitive and specific for the diagnosis and sensitive and specific for the diagnosis and quantitation of myocardial infarction. quantitation of myocardial infarction.

Normal myocardium is darkNormal myocardium is dark 20 to 30 20 to 30 minutes following injection of (Gd-DTPA), a minutes following injection of (Gd-DTPA), a commonly used paramagnetic contrast commonly used paramagnetic contrast agent, because the Gd has washed out agent, because the Gd has washed out and and infracted myocardium is brightinfracted myocardium is bright..

Use of contrast agents has enhanced the Use of contrast agents has enhanced the ability of MRI to distinguish infracted from ability of MRI to distinguish infracted from viable myocardium and so detect cases viable myocardium and so detect cases which may get benefit from further which may get benefit from further treatment treatment (Simonetti et al.,2001).(Simonetti et al.,2001).

Perfusion imaging demonstrating hypoperfusion of a Perfusion imaging demonstrating hypoperfusion of a posterolateral wall infarction.( A) Preinjection study shows posterolateral wall infarction.( A) Preinjection study shows thinning of the posterolateral wall (arrow). (B) Following the thinning of the posterolateral wall (arrow). (B) Following the injection of gadolinium, all normal myocardium enhances; theinjection of gadolinium, all normal myocardium enhances; theinfarcted posterolateral infarcted posterolateral wall does not (arrow). wall does not (arrow).

from from (William & Bradley, 2003).(William & Bradley, 2003).

SUMMARYSUMMARYVarious imaging techniques, including Various imaging techniques, including

Single photon emission computed Single photon emission computed tomography (tomography (SPECTSPECT), Positron emission ), Positron emission tomography (tomography (PETPET), ), echocardiographyechocardiography and and magnetic resonance imaging (magnetic resonance imaging (MRIMRI), have ), have been mostly employed to determine and been mostly employed to determine and localize the extent of myocardial injury localize the extent of myocardial injury and left ventricular dysfunction.and left ventricular dysfunction.

All these investigations can be done All these investigations can be done during during rest and stressrest and stress to determine the residual to determine the residual myocardial reserve. myocardial reserve.

The most important items in evaluation of The most important items in evaluation of lt.vent. function are evaluation of its lt.vent. function are evaluation of its perfusion ,EF. and wall motion.perfusion ,EF. and wall motion.

ConclusionConclusionPerfusion radionuclide imagingPerfusion radionuclide imaging is essential to is essential to

distinguish ischemic cardiomyopathy from distinguish ischemic cardiomyopathy from other causes of dilated cardiomyopathy.other causes of dilated cardiomyopathy.

Both Both stressstress gated SPECTgated SPECT and and stress stress echocardiographyechocardiography with dobutamine can with dobutamine can assess wall motion abnormalities assess wall motion abnormalities especially dyskinetic with aneurysm.especially dyskinetic with aneurysm.

Myocardial Myocardial viability assessmentviability assessment using TI-201 using TI-201 or F18- FDG is essential to stratify patients or F18- FDG is essential to stratify patients with good or poor prognosis and those who with good or poor prognosis and those who benefit from revascularization process. benefit from revascularization process.