Marker Of Myocardial Viability Research Articles

401 Myocardial viability and ischaemia assessment in chronic coronary total occlusions according to collaterals distribution: a retrospective analysis

Abstract Aims Whether CTO-PCI (chronic total occlusions—percutaneous coronary intervention) offers clinical benefit over optimal medical therapy is still a matter of debate. Viability and ischaemia assessment could improve selection of candidates to PCI. Traditionally, well-developed collaterals are considered a marker of myocardial viability in CTO territory. Current literature offers few data concerning the relationship between viability/ischaemia and collaterals distribution. Methods and results We retrospectively analysed the Cardiovascular Magnetic Resonance (CMR) studies and coronary angiographies of patients with at least one CTO referred at Humanitas Research Hospital between June 2009 and September 2020. We included 131 patients who underwent CMR with LGE assessment; of them, 111 (85%) underwent stress-CMR with adenosine. AHA segments (16 segment/patient for a total of 2096 segment assessed) were assessed on three short axis projection and scored for WMSI on cine images, for the presence of ischaemia on first pass perfusion, and for viability on LGE images. Viability was defined as LGE transmurality ≤50% and WMSI (wall motion score index) >1. Patients were divided in three groups according to collaterals distribution at coronary angiography: Patients with TD collaterals were more likely to have viable segments in the CTO-territory (90% of the segments in TD, 76% in WD, and 71% in PD, coeff. 0.107, P < 0.001). No statistically significant differences were found between groups as regard the amount of ischaemic segments (61% of the segments in TD, 65% in WD, and 60% in PD, P = 0.189). Conclusions The presence of myocardial viability is slightly associated with the degree of coronary collateralization at coronary angiography while the amount of ischaemia is not. Stress CMR should be considered in CTO patients before a reopening attempt.

Comparison of Cardio Vascular Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (Pet) for Detection of Myocardial Viability

Coronary artery disease (CAD) remains the most common cause of death. However, the number of deaths from myocardial infarction has decreased. Mortality from congestive heart failure has more than doubled. It is important to note that CAD accounts for the majority (almost 70%) of congestive heart failure cases. In the clinical management of patients with symptom of heart condition by CAD, the correct assessment of cardiac muscle viability is crucial to guide treatment and this will be as a result of revascularization of dysfunctional however viable heart muscle can improve cavity perform and future survival. Generally nuclear imaging, stress echocardiography and stress electrocardiography have been the clinical main step for assessing myocardial viability as well as to detect myocardial Ischemia. Recently cardiovascular MR (CMR) is a rapidly emerging non-invasive imaging technique, providing high resolution images of the heart in any desired plane and without radiation. CMR has the unique ability to evaluate several markers of myocardial viability that are of proven value. The focus of the present study is on the rapidly emerging clinical role of cardiovascular MRI in the detection of viable myocardium. Objective: To assess the role of cardiovascular MRI for detection of myocardial viability

Abstract 10880: Impact of Post-Extrasystolic Potentiation on Takotsubo Cardiomyopathy

Introduction: Takotsubo cardiomyopathy (TCM) is an increasingly recognized condition that presents with transient and reversible left ventricular (LV) dysfunction despite angiographically unobstructed coronary arteries. However the detailed pathophysiology of the stunned myocardium remains to be determined. Post-extrasystolic potentiation (PESP) is an increase in contractility after an extrasystole, thought at least in part due to a net increase in myocardial calcium. When PESP occurs in akinetic LV segments, it is a marker of myocardial viability. Obviously the myocardium in TCM is viable, thus we hypothesized that the affected myocardium in TCM would demonstrate PESP. Methods: We retrospectively reviewed 61 cases of TCM diagnosed by the Mayo criteria between the periods of October 2004 to May 2015. The 24 cases wherein left ventriculography fortuitously provoked extra systoles (PVCs) were evaluated. Results: In our study, the baseline characteristics of TCM were 93.4% female patients with mean age of 67. Mean ejection fraction was 38% and mean troponin I elevation was 5.5. Apical type was the predominant (72.1%) compared to the mid-ventricular type (23.0%). None of the 24 patients in whom ventriculographic PVCs occurred demonstrated PESP in the affected region of the LV, while all did in the unaffected portion. Conclusions: Extra-systoles in TCM fail to elicit PESP in affected LV segments despite proven viability in those segments while unaffected segments behave as predicted. Since increased calcium is thought to be the basis for PESP, it is possible in TCM that either there is failure of calcium release in the affected areas or that the presumed catecholamine excess of TCM has already caused maximum calcium release so PCVs cannot enhance contractility further.

The Efficacy and Tolerability of Azilsartan in Obese Insulin-Resistant Mice with Left Ventricular Pressure Overload

Angiotensin II receptor blockers (ARBs) are used widely for the treatment of heart failure. However, their use in obese and insulin-resistant patients remains controversial. To clarify their potential efficacy in these conditions, we administered azilsartan medoxomil (azilsartan), a prodrug of an angiotensin II receptor blocker to mice fed a high-fat diet (HFD) with left ventricular (LV) pressure overload (aortic banding). LV fibrosis (hydroxyproline), cardiac plasminogen activator inhibitor-1 (PAI-1; a marker of profibrosis), and creatine kinase (a marker of myocardial viability and energetics) were assessed. LV wall thickness and cardiac function were assessed echocardiographically. Mice given a HFD were obese and insulin resistant. Their LV hypertrophy was accompanied by greater LV PAI-1 and reduced LV creatine kinase compared with normal diet controls. Drug treatment reduced LV wall thickness, hypertrophy, and PAI-1 and increased cardiac output after aortic banding compared with results in HFD vehicle controls. Thus, azilsartan exerted favorable biological effects on the hearts of obese insulin-resistant mice subjected to LV pressure overload consistent with its potential utility in patients with analogous conditions.

Parametric imaging of myocardial viability using 15O-labelled water and PET/CT: comparison with late gadolinium-enhanced CMR

PurposeThe perfusable tissue index (PTI) is a marker of myocardial viability. Recent technological advances have made it possible to generate parametric PTI images from a single [15O]H2O PET/CT scan. The purpose of this study was to validate these parametric PTI images.MethodsThe study population comprised 46 patients with documented or suspected coronary artery disease who were studied with [15O]H2O PET and late gadolinium-enhanced (LGE) cardiac magnetic resonance imaging (CMR).ResultsOf the 736 myocardial segments included, 364 showed some degree of LGE. PTI and perfusable tissue fraction (PTF) diminished with increasing LGE. The areas under the curve of the PTI and PTF, used to predict (near) transmural LGE on CMR, were 0.86 and 0.87, respectively. Optimal sensitivity and specificity were 91 % and 73 % for PTI and 69 % and 87 % for PTF, respectively.ConclusionPTI and PTF assessed with a single [15O]H2O scan can be utilized as markers of myocardial viability in patients with coronary artery disease.

Pressure‐wire based assessment of microvascular resistance using calibrated upstream balloon obstruction

We assess microvascular integrity as a marker of myocardial viability after coronary stenting, using only a pressure guidewire. Microvascular integrity generally is not assessed using pressure-only guidewires because the transducer lies upstream of microvasculature. We partially inflate a balloon inside a coronary stent to achieve a specific normalized pressure drop at rest (distal coronary/aortic pressure = 0.8) and then infuse a vasodilator, to render the wire sensitive to microvascular function. We hypothesize that the further decline in pressure (ΔFFR(0.8) ) predicts MRI myocardial viability. We studied 29 subjects with acute coronary syndrome including myocardial infarction. After successful culprit stenting, the resting coronary/aortic pressure was set to 0.8 using temporary balloon obstruction. ΔFFR(0.8) was defined as 0.8-(distal coronary/aortic pressures) during adenosine-induced hyperemia. The average transmural extent of infarction was defined as the average area of MRI late gadolinium enhancement (after 2.8 ± 1.5 days) divided by the corresponding full thickness of the gadolinium enhanced sector in short axis slices, and was compared with ΔFFR(0.8) . ΔFFR(0.8) corresponded inversely and linearly with the average transmural extent of infarction (r(2) = 0.65, P < 0.001). We found that a transmural extent of infarction of 0.50 corresponded to a ΔFFR(0.8) threshold of 0.1, and had high sensitivity and specificity (100% and 94.4%, respectively). Using only an upstream pressure-sensitive guidewire and a partially obstructing balloon during pharmacologic hyperemia, we were able to predict MRI myocardial viability with high accuracy after relief of epicardial stenosis. With further validation, this may prove a useful clinical prognostic tool after percutaneous intervention.

Effects of cardiac resynchronization therapy on myocardial contractile reserve during exercise

Myocardial contractile reserve (MCR) is a marker of myocardial viability. The impact of cardiac resynchronization therapy (CRT) on MCR during exercise has been little studied. Our aim was to investigate the effects of CRT on global and regional MCR by exercise echocardiography. Twenty-seven CRT responders (56% ischaemic) were assessed by echocardiography during rest and bicycle exercise. Images were acquired during spontaneous rhythm ('off') and active CRT ('on'). Global MCR was expressed as the change (Δ) in left ventricular ejection fraction (LVEF) and aortic velocity-time integral (VTI) from rest to exercise. Regional MCR was expressed as the change in peak systolic tissue velocity (Sm) of the septum and lateral wall. Left ventricular ejection fraction and aortic VTI increased at 'on' during rest and exercise, and the increase in global MCR during exercise was higher during 'on' than 'off' (Δ LVEF 6 ± 6 vs. 3 ± 3%; P = 0.009). Septum Sm increased during 'on' at rest, and it was still higher during exercise (P ≤ 0.01), although the absolute change from rest to exercise was similar during 'on' and 'off'. Lateral wall Sm did not change at rest during 'on', but basal lateral wall MCR during exercise was higher at 'on' than 'off' (P = 0.036). In CRT responders, there is a pacing-dependent increase in global MCR during exercise. The changes in regional MCR of the septum and lateral wall show different patterns. These factors may help to understand the determinants of improved exercise tolerance in CRT responders.

Abstract 5697: Echocardiographic Detected Hibernating Myocardium Can Predict Arrhythmic Events in Patients with Ischemic Cardiomyopathy

Backgrounds: In medically treated patients with ischemic cardiomyopathy, myocardial viability is associated with a worse prognosis than scar. Hibernating myocardium (chronic regional dysfunction with reduced resting flow) assessed with nuclear imaging is a major risk factor for cardiac death when left ventricular function is depressed. End-diastolic wall thickness (EDWT) is an important and easy marker of myocardial viability in patients with suspected hibernation, as well as Tl-201 scintigraphy. Thus, in this study, we assessed whether hibernating myocardium evaluated by echocardiography could identify patients with ischemic cardiomyopathy who are at high risk for sudden cardiac death (SCD) and mortality. Methods: Patients with ischemic cardiomyopathy who showed low-grade cardiac function (ejection fraction (EF) &lt; or =50%) and had no plans for coronary revascularization were enrolled. All patients underwent coronary angiography and echocardiography. Hibernating myocardium was defined as the area with major epicardial artery stenosis &gt; or =75%, wall motion abnormality, and EDWT &gt;6mm. The onset of SCD or mortality was determined by outpatient or telephone follow-up. Results: The study patients consisted of 60 consecutive patients (47 men, EF: 35 ± 8%, follow-up duration: 38 ± 16 months). Results were shown in a figure . Hibernating myocardium significantly increased the risk of SCD and mortality. Conclusion: Hibernating myocardium evaluated by echocardiography can predict SCD and mortality in medically treated patients with ischemic cardiomyopathy. Figure Kalpan-Meler Estimates of the Time to SCD or Mortality

Lack of Pathologic Q Waves: A Specific Marker of Viability in Myocardial Hibernation

The present study evaluates the lack of Q waves on the electrocardiogram (ECG) in the prediction of myocardial viability compared with dobutamine stress echocardiography (DSE) and rest-redistribution thallium-201 (Tl-201) scintigraphy. The lack of pathologic Q waves (NoQ) may be a readily available and specific marker for the presence of viability. Sixty four patients with stable coronary artery disease (CAD) and ventricular dysfunction underwent rest ECG, DSE, and Tl-201 scintigraphy before revascularization, and a repeat rest 2-Dimensional (2-D) echocardiogram more than 3 mo later. Total viability at baseline (% of total segments) was higher in the NoQ group by Tl-201 scintigraphy (87 +/- 19% versus 70 +/- 20%, p = 0.008) and by DSE (81 +/- 20% versus 65 +/- 24%, p = 0.013). As expected, the sensitivity of NoQ waves was low in predicting recovery of function (23%), and inferior to Tl-201 (82%) and DSE (84%) (p<0.08). However, specificity of NoQ waves for predicting recovery of global function was high (72%); higher than Tl-201 (50%) and DSE (45%). Positive predictive values were comparable among all modalities. Results were similar if the data were analyzed regionally for viability. Lack of pathologic Q waves is a specific and readily available marker of myocardial viability in patients with chronic CAD, which should alert the clinician for myocardial hibernation.

Comparative assessment of18F-fluorodeoxyglucose PET and99mTc-tetrofosmin SPECT for the prediction of functional recovery in patients with reperfused acute myocardial infarction

Although preserved glucose metabolism is considered to be a marker of myocardial viability in the chronic stage, it has not been fully elucidated whether this is also true with regard to reperfused acute myocardial infarction (AMI). The aim of this study was to compare the diagnostic performance of(99m)Tc-tetrofosmin SPECT and(18)F-fluorodeoxyglucose (FDG) PET for the prediction of functional recovery in reperfused AMI. The study population comprised 28 patients. Both tetrofosmin SPECT and FDG PET were performed in all 28 patients at ca. 2 weeks and in 23 at 6 months. The tetrofosmin and FDG findings in infarct-related segments were compared with the regional wall motion score assessed by left ventriculography over 6 months to determine the predictive value for functional recovery. Of 120 infarct-related segments, 83 had preserved flow (tetrofosmin uptake >/=50%) and 81 had preserved glucose metabolism (FDG uptake >/=40%). The sensitivity and specificity of tetrofosmin SPECT for the prediction of functional recovery tended to be superior to those of FDG PET (90.0% and 72.5% vs 85.0% and 67.5%, respectively). Thirteen segments with preserved flow and decreased glucose metabolism demonstrated marked recovery of contractile function from 2.5+/-1.0 to 1.4+/-1.4 (p<0.01), with restoration of glucose metabolism at 6 months. In contrast, 11 segments with decreased flow and preserved glucose metabolism demonstrated incomplete functional improvement from 3.0+/-0.8 to 2.2+/-1.2. In the subacute phase, preserved myocardial blood flow is more reliable than glucose metabolism in predicting functional recovery in reperfused myocardium.

Usefulness of myocardial contrast echocardiography in predicting collateral blood flow in the presence of a persistently occluded acute myocardial infarction–related coronary artery

Adequate collateral blood flow at rest can sustain myocardial viability despite persistent occlusion of the infarct-related artery (IRA) in acute myocardial infarction (AMI). This has therapeutic and prognostic implications. Studies addressing the value of intravenous myocardial contrast echocardiography (MCE) to detect collateral blood flow after AMI in humans are limited. Accordingly, 70 consecutive patients with AMI underwent low-power intravenous MCE using a Sonovue infusion 7 to 10 days after thrombolysis. Myocardial perfusion detected by MCE was analyzed (qualitatively and quantitatively) in the akinetic segments in 20 patients (29%) with an occluded IRA who subsequently underwent revascularization. Contractile reserve, which is a marker of myocardial viability, was assessed with low-dose dobutamine 12 weeks after mechanical revascularization. Of the 102 akinetic segments (32%), 37 (36%) showed contractile reserve. Contractile reserve was present in 24 of the 29 segments (83%) with homogenous contrast opacification and absent in 60 of the 73 segments (82%) with reduced/absent opacification. Quantitative peak contrast intensity, microbubble velocity, and myocardial blood flow were significantly higher (p <0.0001) in the segments with contractile reserve than in those without contractile reserve. Multiple logistic regression analysis using electrocardiographic, biochemical, and myocardial contrast echocardiographic markers of collateral blood flow showed that MCE (odds ratio 26.0, 95% confidence interval 6.3 to 108.0, p <0.001) was the only independent predictor of collateral blood flow as demonstrated by the presence of contractile reserve. MCE may thus be used as a reliable bedside technique for the accurate evaluation of collateral blood flow in the presence of an occluded IRA after AMI.

Exercise-induced prolongation of the infarct-related Q-waves as a marker of myocardial viability in the infarcted area

Objective: It is known that exercise-induced ischemia in patients with coronary artery disease (CAD) may produce QRS prolongation in the surface electrocardiogram (ECG). To investigate the presence of exercise-induced Q-wave prolongation in patients with single-vessel CAD and Q-wave myocardial infarction (MI), in association with the presence of reversible perfusion defects during thallium scintigraphy in the infarcted area. Methods: 107 consecutive patients (89 males, mean age 56±8 years) were evaluated. All patients underwent coronary arteriography, maximal treadmill exercise testing and thallium-201 scintigraphy. Q-wave duration was measured both before exercise testing and during maximal heart rate from 12-lead ECGs recorded with a paper speed of 50 mm/s. Results: Only 57 out of the 107 studied patients showed reversible perfusion defects in the infarcted area during thallium scintigraphy. Q-wave duration was significantly increased from the resting to the stress ECG (ΔQ-wave duration) in patients with reversible perfusion defects in the infarcted areas (10±13 ms), but not in patients with fixed defects in the infarcted zone (−2.0±5 ms, p<0.01). The sensitivities and the specificities of Q-wave prolongation, ST segment elevation, and the combination of ST segment elevation with ST segment depression in the reciprocal leads for the detection of myocardial viability in the infarcted area were 82%, 48%, 29% and 88%, 50%, and 90%, respectively. Conclusions: Exercise-induced Q-wave prolongation is demonstrated in those patients with single-vessel CAD and a recent MI who show reversible perfusion defects in thallium scintigraphy. Exercise-induced Q-wave prolongation was found to be a sensitive and specific ECG marker for the detection of myocardial viability in the infarcted area.

1280 The ratio between systolic lengtening and post-systolic shortening: a marker of myocardial viability

1280 The ratio between systolic lengtening and post-systolic shortening: a marker of myocardial viability

Valoración de la viabilidad miocárdica en pacientes prerrevascularización

Information on myocardial viability can be useful to decide when coronary artery revascularization is indicated for patients with acute myocardial infarction (AMI) and left regional or global ventricular dysfunction. Difficulties in assessing viability arise because the same part of the ventricular wall can have a mixture of necrotic tissue and viable myocardium. Diagnostic markers of myocardial viability are: the preservation of wall thickness, the presence of contractility reserve, the presence of blood perfusion reserve, integrity of the wall cells, and preservation of cellular metabolism. Echocardiography and thallium or technetium imaging are methods currently used to assess myocardial viability because of their availability and relatively low cost. Although positron emission tomography (PET) has been considered the gold standard, its unavailability may limit its clinical use. Recent publications have demonstrated the accuracy of cardiac magnetic resonance imaging (cardiac MRI) in assessing myocardial viability, together with noninvasive procedures to study the markers of viability noted above. Late contrast enhancement with gadolinium is the most accurate and simplest method. The late open artery hypothesis recommends, on the basis of scant evidence, systematic revascularization of the culprit artery. Although no large randomized studies focused on prognosis are available yet, several small studies provide sufficient evidence of functional recovery of viable myocardium after coronary artery revascularization of the culprit artery in patients with global or regional ventricular dysfunction. The assessment of myocardial viability to decide whether culprit artery revascularization is indicated is a strategy currently based on more evidence than the more indiscriminate recommendations based on the late open artery hypothesis.

Perfusable tissue index obtained by positron emission tomography as a marker of myocardial viability in patients with ischemic ventricular dysfunction.

In areas of severe asynergy, the clinically important task is to identify functionally recoverable myocardium. Fourteen patients with asynergy were investigated by H2(15O) dynamic positron emission tomography imaging before revascularization. Regional myocardial blood flow (MBF) was determined and the water-perfusable tissue fraction (PTF) for each region of interest and the total anatomical tissue fraction (ATF) were estimated. The PTF/ATF was analyzed as the water perfusable tissue index (PTI). Asynergy was defined as segments with wall motion more than 2SD below than that of a normal population. An increase of >0.8SD in anterior wall segments with asynergy and an increase of >0.6 SD in inferior wall asynergy were defined as significant improvements of wall motion indicative of viable myocardium. Fifteen segments with wall motion abnormalities less than -2SD and 10 control segments were identified; 7 segments recovered and 8 segments did not. MBF was similar in both groups of segments before revascularization (0.78 +/- 0.27 vs 0.73 +/- 0.18 ml min-(-1) x g(-1), NS). The PTI in the recovered segments was significantly higher than that in the unimproved segments (0.734 +/- 0.058 vs 0.592 +/- 0.038, p<0.0001) and was similar to that of the control segments. After revascularization, the PTI correlated with the SD of wall motion (p<0.05, r=0.58). PTI may be a good predictor of contractile recovery after revascularization.

The use of Gd-DTPA as a marker of myocardial viability in reperfused acute myocardial infarction.

At present, accurate assessment of the extent of myocardial viability after acute myocardial infarction is limited due to the spatial resolution of currently available imaging modalities. MR cardiac imaging, with its superior spatial resolution, would be used if viable and infarcted tissue could be separated based on signal intensity. In infarcted tissue, cell membrane breakdown allows the entry of the MR contrast agent Gd-DTPA which is normally extracellular. The increased space for Gd-DTPA distribution (partition coefficient, lambda) in this infarcted tissue results in increased Gd-DTPA concentration and hence increased signal intensity on T1-weighted MR images. In a canine model of ischemia/reperfusion injury, the partition coefficient in infarcted tissue increased as early as 1 min post reperfusion. lambda in infarcted tissue stayed increased over that in normal tissue for at least 8 weeks. The accuracy of contrast-enhanced MRI was confirmed by results of 201Tl SPECT and a cine MRI dobutamine wall motion study in a patient 1 week after an acute myocardial infarction. Thus, contrast-enhanced MRI shows great promise for the non-invasive determination of myocardial viability after acute myocardial infarction.

The effect of ischemic injury on the cardiac transport of Tc-99m N-NOET in the isolated rabbit heart

Background. Bis (N-ethoxy, N-ethyl dithiocarbamato) nitrido technetium-99m (V) (TcN-NOET) is a neutral lipophilic myocardial perfusion agent. The effect of ischemic injury on the cardiac transport of TcN-NOET and thallium-201 was determined in isolated rabbit hearts. Methods and Results. The multiple indicator dilution method was used to determine the maximum (E max) and net extraction (E net, at 5 minutes) of TcN-NOET and Tl-201 at control and after 10 minutes (n = 4) or 45 minutes (n = 4) of no-flow ischemia. After 10 minutes of ischemia the mean E max for Tl-201 was unchanged, 0.86 ± 0.03 vs 0.85 ± 0.02, whereas Tl-201 E net showed a small decrease from 0.46 ± 0.03 to 0.40 ± 0.03, P < .001. Forty-five minutes of ischemia mildly reduced E max for Tl-201 (0.87 ± 0.04 to 0.74 ± 0.04, P < .001) and severely reduced E net (0.46 ± 0.03 vs 0.16 ± 0.04, P < .001). Neither E max nor E net for TcN-NOET was significantly affected by 10 minutes of ischemia (0.54 ± 0.04 vs 0.58 ± 0.03 and 0.24 ± 0.04 vs 0.26 ± 0.04, respectively). However, severe ischemic injury caused significant reductions versus control in both E max (0.59 ± 0.06 vs 0.42 ± 0.05, P < .001) and E net (0.27 ± 0.03 vs 0.18 ± 0.05, P < .01). Conclusions. TcN-NOET is a new myocardial perfusion agent with moderate myocardial extraction. Although less sensitive than Tl-201 to mild ischemic injury, TcN-NOET extraction and retention are decreased by severe ischemic injury, making uptake of TcN-NOET a possible marker of myocardial viability.

Assessment of myocardial viability by MRI

Assessment of myocardial viability has become an important issue in patients presenting with either acute myocardial infarction or presenting with chronic ischemic left ventricular dysfunction. In patients with viable myocardium recovery of left ventricular function can be anticipatedm, spontaneously in patients with acute myocardial infarction or following revascularization in patients with ischemic cardiomyopathy. In contrast, patients without viable tissue are not likely to improve in left ventricular function. Currently, nuclear imaging techniques and dobutamine stress echocardiography are used for assessment of viability; recent studies with magnetic resonance imaging (MRI) have however demonstrated the potential usefulness of this technique for the assessment of viability. Various parameters, derived from resting MRI, can be used as markers of myocardial viability, including the end-diastolic wall thickness, systolic wall thickening and signal intensity without contrast-enhancement. Other studies have combined the information from resting MRI with the assessment of contractile reserve during dobutamine stimulation. Finally, recent studies have evaluated the use of contrast-enhanced MRI to detect viable myocardium. All of these parameters are potentially useful and MRI provide an alternative approach for the assessment of viable myocardium.

Difference of Tl-201 uptake between redistribution and rest is a specific marker of myocardial viability

Difference of Tl-201 uptake between redistribution and rest is a specific marker of myocardial viability

Assessment of myocardial viability with 99mTc-sestamibi tomography before coronary bypass graft surgery: correlation with histopathology and postoperative improvement in cardiac function.

Assessment of myocardial viability by 99mTc-sestamibi remains controversial. Accordingly, we investigated the use of sestamibi as a marker of myocardial viability, defined by histopathology, and for predicting improvement of myocardial function after coronary artery bypass graft surgery (CABG). 99mTc-sestamibi perfusion tomography and radionuclide angiography were performed within 2 days before CABG in 21 patients with > or = 75% stenosis of the left anterior descending coronary artery and resting anterior wall dyssynergy. During CABG, transmural myocardial biopsies were obtained from the dyssynergic anterior wall and from normal myocardial segments to determine the extent of viable myocardium by histopathology. Improvement of regional left ventricular function was evaluated by radionuclide angiography at 6 to 8 weeks after CABG. There was a good correlation (r=.85, P<.001) between the quantified sestamibi activity and the extent of viable myocardium determined morphometrically. Among 21 biopsied dyssynergic myocardial segments, 11 improved their function after CABG and 10 failed to improve. Biopsied segments with improved postoperative function had significantly higher sestamibi activity (81+/-5% versus 49+/-16%, P<.0001) and significantly lower extent of interstitial fibrosis (7+/-4% versus 31+/-21%, P=.0002) than segments that failed to improve. A 55% threshold of 99mTc-sestamibi activity had positive and negative predictive values of 79% and 100%, respectively, for recovery of function after CABG in the biopsied segments. Myocardial 99mTc-sestamibi activity correlates well with the extent of viable myocardium and predicts improvement in regional function after CABG. This lends support to the use of sestamibi as a myocardial viability agent.