Assessment of viable myocardium by dobutamine transesophageal echocardiography and comparison with fluorine-18 fluorodeoxyglucose positron emission tomography

Objectives. The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction.Background. Experimental and clinical studies have shown that dobutamine can recruit a contraction reserve in postischemic viable but akinetic segments, indicating that dobutamine-induced functional recovery is a potential ultrasound marker of myocardial viability.Methods. Forty patients underwent rest and dobutamine transesophageal echocardiography (dobutamine 5, 10 and 20 μg/kg body weight per min) and fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography at rest. Three representative shortaxis tomograms and a transverse four-chamber-view were used for wall motion and F-18 fluorodeoxyglucose-uptake analysis in corresponding myocardial regions. A basally asynergic segment was considered viable by transesophageal echocardiography if dobutamine-induced systolic wall motion could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake ≥50% of the maximal uptake in a region with normal wall motion by left ventriculography.Results. Functional recovery within the infarct region was found in 21 (53%) of 40 patients during dobutamine infusion. Infarct region-related viability by F-18 fluorodeoxyglucose uptake was diagnosed in 25 (63%) of 40 patients, yielding a diagnostic agreement between both techniques in 90% of patients. In 210 (89%) of 235 akinetic segments at rest, data on myocardial viability were concordant by the two techniques. The positive and negative predictive accuracy of dobutamine transesophageal echocardiography for viability defined by F-18 fluorodeoxyglucose uptake was 81% and 97%, respectively. Such uptake was significantly different (p < 0.001) between segments remaining akinetic (mean ± SD 45 ± 9%) during dobutamine infusion and segments with a dobutamine-induced contraction reserve (68 ± 11%).Conclusions. Dobutamine transesophageal echocardiography provides a promising low cost and widely available approach to unmask myocardial viability in patients with chronic myocardial infarction, and results compare favorably with those of F-18 fluorodeoxyglucose positron emission tomography.     

Prediction of viability by pulsed-wave Doppler tissue sampling of asynergic myocardium during low-dose dobutamine challenge

Dobutamine stress echocardiography is widely used to predict reversible left ventricular dysfunction, but evaluation with this method is subjective. Pulsed-wave tissue Doppler imaging is a new technique that allows to obtain quantitative data on wall motion velocities of different myocardial segments through sample-volume placement. Therefore, this tool in combination with DSE may be suitable for identifying viability in asynergic myocardium. To evaluate this, in 40 patients (mean age 57+/-9) with resting dyssynergy (akinesis in 52, hypokinesis in 30) baseline wall motion scores and tissue Doppler variables were collected before and after 5 min infusion of 10 microg/kg per min dobutamine. Forty-six of 82 segments were classified as viable (a reduction in segmental score of at least one grade) according to follow-up echocardiography that was performed 4 weeks after revascularization. While myocardial S velocity percent increase in viable segments was 45+/-10, the increase was 25+/-12 in necrotic segments (n=36) during 10 microg dobutamine infusion (P=0.0001). Assuming 35% as a cut-off for viability the increase in S velocities by DSE yielded an 89% sensitivity and 86% specificity for predicting post-revascularization functional recovery. In conclusion, pulsed-wave tissue Doppler imaging of asynergic myocardium during dobutamine stress echocardiography can identify the viability quantitatively.     

Comparison of dobutamine echocardiography and rest-redistribution 201-thallium SPECT in the assessment of myocardial viability taking PET as gold standard]

BACKGROUND AND AIM: To compare Tl-201 SPECT and dobutamine stress echocardiography for the detection of myocardial viability in patients with severe left ventricular dysfunction using metabolic imaging by positron emission tomography as the standard reference. MATERIAL AND METHODS: We studied 25 consecutive patients with severe coronary artery disease and left ventricular dysfunction that underwent two different diagnostic modalities for evaluating myocardial viability: stress echocardiography with incremental doses of dobutamine from 5 up to 40 g/kg/min in 3 min stages, and 201 Tl SPECT using a rest-redistribution protocol with delayed images obtained at 4 hours. Fluorodeoxyglucose uptake by PET was used as the gold standard. Viability criteria were as follows, for 201Tl SPECT imaging: normal uptake at rest and presence of redistribution in the delayed images, for dobutamine stress echocardiography: sustained improvement and biphasic response. RESULTS: Sensitivity of thallium redistribution was 46%, for normal uptake, plus redistribution 82%, 34% for dobutamine biphasic response and 58% for sustained improvement plus biphasic response. Specificity of biphasic response was 82% and that of redistribution 67%. Stepwise logistic regression indicated that biphasic wall motion response during dobutamine stress echocardiography (2.01 CI 95%; 1.10 to 3.99) and the presence of redistribution plus normal uptake at rest with thallium imaging (2.68 CI 95%; 1.42 to 5.13) were the best predictors of viability. These results were the same when both techniques were analyzed together. CONCLUSIONS: Biphasic wall motion response during dobutamine stress echocardiography and the normal uptake plus presence of redistribution with thallium imaging were the best pre     

Additive value of low-dose dobutamine to technetium-99m sestamibi-gated single-photon emission computed tomography for prediction of wall motion improvement in patients undergoing coronary artery bypass graft

BACKGROUND: The two most useful methods for myocardial viability assessment are perfusion imaging and dobutamine echocardiography. HYPOTHESIS: The present study investigated the additive value of a new method, dobutamine technetium 99m (99mTc)-sestamibi-gated single-photon emission computed tomography (SPECT), which combines these two modalities, to the prediction of wall motion improvement after revascularization. METHODS: Fifty-five consecutive patients with ischemic cardiomyopathy, who were referred for viability evaluation, underwent resting and dobutamine (dose, 5-10 microkg/kg/min) gated SPECT with 99mTc-sestamibi. Of these patients, 36 underwent coronary artery bypass graft (CABG) within 1 month of the study and 32 had repeat resting gated SPECT within 1 year. Global and regional wall motion, wall thickness, and perfusion were simultaneously analyzed at rest and after dobutamine using the 20-segment model; the sestamibi uptake and wall motion response to dobutamine of each segment were rated quantitatively. Based on these findings, the segments were categorized as normal, viable, or nonviable. The predictive values for wall motion improvement were assessed by perfusion, using cutoffs of 50 and 60% of sestamibi uptake, and thereafter by the addition of dobutamine response in the segments that were rated nonviable. RESULTS: Of the 1,080 myocardial segments studied, 906 (84%) had abnormal wall motion and were analyzed for viability. Concordance between perfusion and wall motion response to dobutamine was 60% with the 50% cutoff of sestamibi uptake, and increased to 65% with the 60% sestamibi cutoff (p < 0.04). The respective predictive values of wall motion improvement using the 50 and 60% cutoff points were as follows: sensitivity 93 and 70%, respectively, (p < 0.01); specificity 59 and 86% (p < 0.001), respectively; accuracy 77% for both. The addition of the wall motion response to dobutamine to the assessment of the nonviable segments by perfusion (60% cutoff) increased the sensitivity from 70 to 85% (p = 0.001) and the negative predictive value from 70 to 81% (p = 0.009); the positive predictive value remained high (86 vs. 82%). No additive value of wall motion response to dobutamine was demonstrated for nonviable segments by perfusion with a 50% cutoff. CONCLUSION: Dobutamine sestamibi-gated SPECT is a feasible method for the analysis of myocardial perfusion, function, and contractile reserve of individual myocardial segments in patients with ischemic cardiomyopathy. Viability assessment based on a threshold of 60% uptake of sestamibi, with the addition of the wall motion response to dobutamine in the nonviable segments, seems to yield better predictive values for wall motion improvement after CABG.     

Comparison of dobutamine echocardiography, dobutamine sestamibi, and rest-redistribution thallium-201 single-photon emission computed tomography for determining contractile reserve and myocardial ischemia in ischemic cardiomyopathy.

Both dobutamine stress echocardiography (DSE) and myocardial perfusion scintigraphy are used to assess myocardial viability. Few studies have compared the data on myocardial viability and ischemia by low and peak dose DSE and myocardial perfusion imaging in the same patients. Fifty-four patients (45 men and 9 women aged 65 +/- 9 years) with ischemic cardiomyopathy (mean ejection fraction 24 +/- 9%) underwent rest 4-hour redistribution thallium-201 single-photon emission computed tomography (SPECT), low and peak dose DSE, and dobutamine sestamibi SPECT. A total of 864 segments were analyzed (16 segments/patient). Wall motion abnormality was present in 796 segments (92%), and contractile reserve during dobutamine infusion was seen in 400 of these segments (50%). Contractile reserve was seen in 331 of 509 hypokinetic segments (65%) and 69 of 287 akinetic/dyskinetic segments (24%) (p <0.001). Contractile reserve was more frequent in segments with normal thallium uptake (64%), reversible thallium defects (42%), or mild to moderate fixed thallium defects (48%) than severely fixed defects (22%) (p <0.05 each). Concordant information about viability by thallium imaging and DSE was obtained in 62% of segments. Dobutamine sestamibi ischemia was seen in 518 of 796 segments (65%) compared with 265 segments (33%) by DSE (p <0.001). Scintigraphic ischemia was noted in 126 of 195 segments (65%) demonstrating biphasic response, 129 of 205 segments (63%) showing sustained improvement, 42 of 70 segments (60%) deteriorating during dobutamine infusion, and 221 of 326 (68%) demonstrating no change (p = NS). Thus, in patients with ischemic cardiomyopathy, contractile reserve is more frequent in hypokinetic segments than akinetic/dyskinetic segments. The number of segments with normal or near-normal thallium uptake or with scintigraphic ischemia is significantly greater than the number of those capable of increasing contractile function or demonstrating an ischemic response during dobutamine echocardiography.     

Post-systolic shortening during dobutamine stress echocardiography predicts cardiac survival in patients with severe left ventricular dysfunction

BACKGROUND: Patients with severe left ventricular dysfunction and myocardial viability by dobutamine stress echocardiography (DSE) or F18-fluorodeoxyglucose-single-photon emission computed tomography (FDG-SPECT), experience improved survival after coronary revascularization. Pulsed wave-tissue Doppler imaging (PW-TDI)-derived ejection phase shortening (EPS) and post-systolic shortening (PSS) velocities may help to quantify DSE. We assessed these variables in a prospective long-term follow-up. METHODS: Eighty patients (58 men, mean age 63+/-9 years) with left ventricular dysfunction (radionuclide ventriculography mean ejection fraction, 34+/-11%) underwent both DSE and FDG-SPECT for myocardial viability. Viable myocardium was improvement from rest to low dose or worsening of wall motion at peak DSE and normal perfusion, mildly reduced perfusion with FDG uptake or severely reduced or absent perfusion with increased FDG uptake (mismatch) at FDG-SPECT. EPS, PSS velocities and EPS/PSS ratio during DSE were analysed using a six-segment model. Coronary revascularization bypass grafting was performed in 62 patients. All patients completed a long-term (9-year) follow-up for cardiac death. RESULTS: The segmental prevalence of severe dyssynergy was 77%. On a patient basis myocardial viability was detected by EPS/PSS ratio (31%), FDG-SPECT (34%) and DSE (26%). A significant improvement of Kaplan-Meier survival was predicted in viable compared with nonviable revascularized patients (P < 0.01). Both EPS/PSS ratio and FDG-SPECT, compared to DSE alone, tended to allocate more accurately univariate prediction of death-free outcome (odds ratio, 2.5 and 2.7 compared with 2.1). CONCLUSIONS: TDI adds objective variables to DSE, helping to recognize viable myocardium and optimize prediction of death-free outcome in long-term follow-up, with favorable comparison with nuclear techniques.     

Predictive value of low dose dobutamine transesophageal echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography for recovery of regional left ventricular function after successful revascularization

Objectives. This study was designed to assess the predictive value of myocardial viability diagnosed by dobutamine transesophageal echocardiography and fluorine (F)-18 fluorodeoxyglucose positron emission tomography for left ventricular functional recovery after revascularization in patients with chronic left ventricular dysfunction.Background. The identification of akinetic but viable myocardium is of particular importance for the selection of patients with a compromised left ventricle who will benefit from coronary revascularization.Methods. Multiplane rest and dobutamine transesophageal echocardiography (dobutamine, 5 and 10 μg/min per kg) studies and F-18 fluorodeoxyglucose positron emission tomographic studies at rest were performed in 42 patients with 1) previous myocardial infarction and regional akinesia, 2) a stenosed infarct-related coronary artery, and 3) a patent infarct-related vessel after revascularization. A basally akinetic segment was considered viable by transesophageal echocardiography if dobutamine-induced contractile reserve could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake ≥50% of the maximal uptake in a region with normal wall motion. Recovery of regional left ventricular function 4 t0 6 months after revascularization was diagnosed by transesophageal echocardiography if ≥50% of segments akinetic at baseline had improved wall thickening.Results. Dobutamine transesophageal echocardiography identified viable infarct regions in 25 (59%) of 42 patients, and F-18 fluorodeoxyglucose positron emission tomography in 30 (71%) of 42 patients, yielding diagnostic agreement in 86% of patients. Sensitivity and specificity for prediction of left ventricular functional recovery in individual patients was 92% and 88%, respectively, for dobutamine transesophageal echocardiography versus 96% and 69% for F-18 fluorodeoxyglucose positron emission tomography. Segments remaining akinetic after revascularization had a significantly lower (p < 0.001) F-18 fluorodeoxyglucose uptake (48 ± 15%) than that (73 ± 15%) of segments with recovery of regional left ventricular function.Conclusions. Both dobutamine transesophageal echocardiography and F-18 fluorodeoxyglucose positron emission tomography were highly sensitive in predicting functional recovery of chronically kinetic or dyskinetic myocardium after successful revascularization. Thus, dobutamine transesophageal echocardiography is a clinically valuable alternative to F-18 fluorodeoxyglucose positron emission tomography for assessing residual viability and predicting functional recovery after revascularization.     

Tissue velocity imaging during dobutamine stimulation for assessment of myocardial viability: segmental analysis in patients after myocardial infarction

BACKGROUND: Dobutamine stress echocardiography (DSE) is an established method for the detection of viable myocardium, but evaluation of this method is subjective. Tissue velocity Imaging (TVI) allows quantitative analysis of regional myocardial wall motion by assessment of systolic myocardial velocities. The aim of this study was to evaluate the diagnostic value of DSE and TVI for detection of viable myocardium. METHODS: In 56 patients (58+/-12 years) with previous myocardial infarction (130+/-42 days, mean ejection fraction 42+/-15%) low-dose DSE was combined with analysis of peak systolic myocardial velocities (Vpeak) by TVI for assessment of myocardial viability. As reference served a follow-up echocardiography after successful revascularization (mean 91+/-3 days). RESULTS: Of a total of 896 segments 200 showed abnormal wall motion (31 mildly hypokinetic, 50 severely hypokinetic, 115 akinetic, 4 dyskinetic). In 125 of these 200 segments regional improvement of regional wall motion was observed (62.5% viable). An increase of Vpeak>1 cm/s during dobutamine stimulation allowed the identification of viable myocardium with a sensitivity of 82% and a specificity 82% (DSE: 77% and 80%). By receiver operating characteristic (ROC) curve analysis, a cut-off value of 1.0 cm/s was the best parameter to differ viable from nonviable myocardium (area under the curve 0.85; p<0.01; 95% CI 0.79 to 0.90). Improvement of global ejection fraction after revascularization (47+/-13%, p=0.11) corresponded with three TVI viable segments with a sensitivity of 92% and a specificity of 89% (p=0.012). CONCLUSIONS: TVI allows the identification of viable myocardium during dobutamine stimulation and enables a quantitative interpretation of DSE.     

MRI for the diagnosis of myocardial ischemia and viability

Assessment of myocardial ischemia and viability plays a crucial role in the clinical management of patients with coronary artery disease. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. MRI is able to evaluate both myocardial perfusion as well as myocardial contractile reserve. Because of its superior spatial resolution, integration of qualitative and quantitative methodology, and excellent reproducibility, MRI has advantages over conventional noninvasive modalities currently used in the evaluation of myocardial ischemia and viability, and may well emerge as the premier noninvasive technique in the assessment of patients with coronary artery disease. The authors review the rapidly expanding recent literature that has now established cardiovascular MRI (including dobutamine cine MRI and vasodilator perfusion MRI techniques) as an ideal choice in the evaluation of myocardial ischemia and delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of viability. Comparisons with more established techniques such as dobutamine stress echocardiography, single photon emission computed tomography perfusion imaging, and positron emission tomography are reviewed.     

Significance of dobutamine-induced ST-segment evaluation and T-wave pseudonormalization in patients with Q-wave myocardial infarction: simultaneous evaluation by dobutamine stress echocardiography and thallium-201 SPECT.

The clinical significance of stress-induced ST-segment elevation and T-wave pseudonormalization in infarct-related leads is still controversial. Therefore, we conducted the present study to assess this issue using simultaneous dobutamine stress echocardiography (DSE) and thallium-201 single-photon emission computed tomography. A total of 119 patients with Q-wave myocardial infarction were enrolled in this study. There were 58 patients with (group I) and 61 patients without (group II) dobutamine-induced ST-T changes. Left ventricular ejection fraction was 43 +/- 13% in group I and 49 +/- 14% in group II (p <0.05). The baseline, low-, and peak-dose global wall motion scores were similar between these 2 groups (26.2 +/- 6.1 vs 26.2 +/- 6.3 [p = NS]; 24.1 +/- 5.3 vs 23.5 +/- 5.7 [p = NS]; 26.4 +/- 5.7 vs 26.7 +/- 6.1 [p = NS]). The sensitivity, specificity, and accuracy of these ST-T changes for detecting residual myocardial viability and ischemia documented by DSE in all patients were 50%, 53%, and 51% (for viability), and 47%, 48%, and 47% (for ischemia), respectively. The sensitivity, specificity, and accuracy of these ST-T changes for detecting a reversible perfusion defect documented by thallium-201 single-photon emission computed tomography were 51%, 54%, and 52%, respectively. In conclusion, dobutamine-induced ST elevation and/or T-wave pseudonormalization is associated with poor resting left ventricular function. These ST-T changes are not associated with residual myocardial ischemia and viability in the infarct area. Therefore, these electrocardiographic changes alone cannot be reliably considered as distinctive markers in formulating the therapeutic strategy of coronary intervention.     

Pulsed Tissue Doppler Imaging to Assess Myocardial Viability by Quantification of Regional Myocardial Functional Reserve

Dobutamine stress echocardiography (DSE) is used widely to evaluate myocardial viability, but is limited by the subjective nature of test interpretation. Assessment of systolic function by pulsed tissue Doppler imaging (TDI) during dobutamine stimulation may allow a more objective evaluation of myocardial functional reserve and, thus, myocardial viability. In 30 patients (58 +/- 9 years) with prior myocardial infarction, pulsed TDI with low dose dobutamine stress (10 microg/kg/min) was performed to assess myocardial viability. Qualitative assessment of two-dimensional (2-D) DSE and positron emission tomography (PET) were used for comparison. Peak systolic myocardial velocity was measured for each left ventricular segment (16 segments) at baseline and low dose dobutamine stress using pulsed TDI. The absolute and relative increases of peak systolic velocity from rest to low dose dobutamine stress were calculated. Three hundred sixty-four segments with adequate pulsed TDI tracing were divided according to either 2-D DSE or PET findings into normal, viable (mismatch), and nonviable (match) segments. The increase of peak systolic myocardial velocity from baseline to low dose dobutamine was significantly different between segments defined as normal, viable, and nonviable by 2-D DSE (2.71 +/- 1.91 cm/sec, 1.86 +/- 2.15 cm/sec, and 0.99 +/- 1.16 cm/sec, respectively; P < 0.001). The increase of peak systolic myocardial velocity from rest to low dose dobutamine for normal, mismatch, and match segments defined by PET was 2.72 +/- 1.96, 1.01 +/- 0.96 and 0.80 +/- 1.07 cm/sec, respectively (P < 0.001). In conclusion, the increase of peak systolic myocardial velocity during low dose dobutamine stimulation determined by pulsed TDI distinguishes between different myocardial viability states. It complements the standard interpretation of stress echocardiograms.     

Assessment of myocardial viability with dobutamine stress echocardiography in patients with ischemic left ventricular dysfunction

The noninvasive assessment of myocardial viability has proved clinically useful for distinguishing hibernating and/or stunned myocardium from irreversibly injured myocardium in patients with chronic ischemic heart disease or recent myocardial infarction, with marked regional and/or global left ventricular (LV) dysfunction. Noninvasive techniques utilized for the detection of viability in asynergic myocardial regions include positron emission tomographic imaging of residual metabolic activity, single photon emission tomography (SPECT) of radioisotope uptake with thallium-201, low-dose dobutamine echocardiography assessment of inotropic reserve and myocardial contrast echocardiography for evaluation of microvascular integrity. Of these techniques, dobutamine stress echocardiography is a safe, widely available and relatively inexpensive modality for the identification of myocardial viability for risk stratification and prognosis. Low-dose dobutamine response can accurately predict improvement of dysfunctional yet viable myocardial regions, and thus identify a subset of patients whose LV function will improve following successful coronary revascularization.     

Magnetic resonance imaging during dobutamine stress in coronary artery disease.

Cine magnetic resonance imaging (MRI) provides a tomographic method of assessing regional ventricular function in any desired plane. It has not been possible to obtain adequate images during dynamic exercise, and this has limited its value in patients with coronary artery disease (CAD). Therefore, an infusion of dobutamine was used to study 25 patients with exertional chest pain and abnormal exercise electrocardiograms. Areas of abnormal wall motion were compared with areas of abnormal myocardial perfusion imaged by dobutamine thallium emission tomography and with coronary arteriography. Twenty-two patients had significant CAD. Twenty-one (96%) of these patients had reversible myocardial ischemia shown by dobutamine thallium tomography, and 20 (91%) had reversible wall motion abnormalities shown by dobutamine MRI. Comparison of abnormal segments of perfusion and wall motion showed 96% agreement at rest, 90% agreement during stress, and 91% agreement for the assessment of functional reversibility. The normalized magnetic resonance signal intensity of the ischemic segments showed a small but significant reduction when compared with that of normal segments (-67 units [9.2%]; p less than 0.05). Dobutamine infusion was well-tolerated, despite causing chest discomfort in 24 patients (96%). Nine patients (36%) developed a minor dysrhythmia that was usually ventricular premature complexes, but this did not limit infusion, and other side effects were mild. The short plasma half-life of dobutamine makes it ideal as a stress agent for imaging techniques (such as MRI), and these results suggest that it is more effective in the provocation of wall motion abnormalities than is dipyridamole in patients with CAD.     

Comparison of real-time myocardial contrast echocardiography for the assessment of myocardial viability with fluorodeoxyglucose-18 positron emission tomography and dobutamine stress echocardiography

Little is known about the diagnostic value of real-time myocardial contrast echocardiography (MCE) for the assessment of myocardial viability. We compared the diagnostic accuracy of MCE with that of low-dose dobutamine stress echocardiography (DSE) and of combined technetium-99 sestamibi single-photon emission computed tomography and fluorodeoxyglucose-18 positron emission tomography and investigated whether quantitative assessment of myocardial blood flow could increase its diagnostic value. Cardiac imaging was performed with these 3 methods in 41 patients who had ischemic heart disease (ejection fraction < 40%) and were being considered for revascularization. Follow-up echocardiograms were obtained after 3 to 6 months in revascularized patients, and increased regional function served as a standard reference for assessment of myocardial viability. A control group of 25 patients who had no coronary artery disease underwent MCE to assess normal values of myocardial perfusion parameters. Recovery of myocardial function was predicted by MCE with a sensitivity of 86% and a specificity of 43%. Nuclear imaging was comparably sensitive (90%) and specific (44%), whereas low-dose DSE was similarly sensitive (83%) but more specific (76%). Normalization of myocardial signal intensity to that of the control group significantly increased the specificity of MCE from 43% to 64% and the accuracy from 73% to 81%. A combination of quantitative MCE and DSE provided the best diagnostic characteristics, with a sensitivity of 96%, a specificity of 63%, and an accuracy of 83%. Thus, MCE is useful for assessing myocardial viability. Normalization of contrast intensity to that of a reference control group is a valid approach for detection of myocardial viability and expands on information obtained from visual MCE and DSE.     

The use of dobutamine stress echocardiography for the determination of myocardial viability

Determining the presence of viable myocardium has prognostic and therapeutic implications in the treatment of ischemic heart disease. Dobutamine stress echocardiography (DSE) is one possible technique to help identify both hibernating and stunned but viable myocardium. Low-dose dobutamine infusion has an increased inotropic effect, while higher doses cause both inotropic and chronotropic effects. Thus, at lower doses cardiac augmentation occurs, and at higher doses regions of ischemia may be produced in the presence of significant coronary artery disease. This is manifested echocardiographically as changes in segmental wall motion. in theory, therefore, areas of viable myocardium should show improved wall motion at low doses, and areas of irreversible myocardial damage will remain akinetic. Five studies have investigated DSE for determining viability in the setting of acute myocardial infarction, thus looking for stunned but viable myocardium. DSE was shown to compare favorably with positron emission tomography and was highly sensitive and specific for predicting functional myocardial recovery. Five additional studies examined DSE for determining the presence of hibernating myocardium. The sensitivity and specificity of DSE were found to range from 71 to 92% and from 73 to 93%, respectively. The benefits of DSE include lower cost, convenience to both patient and physician, additional ancillary information, and determination of the possible need for urgent revascularization. Limitations of DSE include occasional technical difficulty in obtaining and interpreting studies and the need for larger volumes of viable myocardium to detect changes predictive of functional recovery. Larger trials are currently underway to confirm DSE as a reliable technique for determining myocardial viability.     

Reverse redistribution of thallium-201 myocardial single photon emission tomography and contractile reserve

The present study investigated the contractile reserve of myocardium exhibiting reverse redistribution (RRD) of thallium-201 (201Tl) after acute myocardial infarction. Forty patients experiencing their first acute myocardial infarction underwent resting 201Tl single-photon emission computed tomography (SPECT) and low-dose (5-10 microgxkg(-1)xmin(-1)) dobutamine stress echocardiography (DSE) within 4 weeks after the onset of infarction. The left ventricle was divided into 13 segments for analysis. The severity of defects in 201Tl SPECT and the extent of wall motion abnormality in DSE were visually assessed and scored. The sum of each defect score and wall motion score of infarct-related segments were defined as total defect score (TDS) and total wall motion score (TWM), respectively. Quantitative analysis of 201Tl uptake was also performed. Resting 201Tl SPECT revealed RRD in 16 patients (group RRD), fixed defect (FIX) in 23 patients (group FIX), and redistribution in one. There was a significant difference in improvement of TWM between rest and stress in TWM in both the RRD and FIX groups (p<0.0001, each case). The improvement of TWM with dobutamine was significantly greater in RRD than in FIX (1.6+/-1.0 vs 0.6+/-0.7, p=0.001). There was a positive correlation between the magnitude of RRD and improvement of TWM with dobutamine (r=0.48, p=0.002). Myocardium exhibiting RRD on 201Tl SPECT in patients with acute myocardial infarction has greater contractile reserve than that exhibiting a fixed defect.     

Left ventricular dysfunction during dobutamine stress echocardiography in patients with syndrome X and positive myocardial perfusion scintigraphy.

AIMS: A sizeable proportion of patients with angina, angiographically smooth coronary arteries and positive exercise test (syndrome X) have stress/rest myocardial perfusion defects. The aim of the study was to assess whether perfusion defects are dependent upon a reduction in coronary flow reserve causing regional left ventricular dysfunction in syndrome X patients. METHODS AND RESULTS: Twenty-two syndrome X patients underwent dobutamine stress echocardiography (DSE). All had stress-induced perfusion defects documented by 99m-Tc-MIBI scintigraphy. Resting and peak DSE wall motion score index (WMSI) were evaluated. Six patients exhibited resting wall motion abnormalities in 10 segments (WMSI 1.05 +/- 0.11). DSE was positive in 12 patients (53%), in whom 16 myocardial segments were involved: of these, 12 were normokinetic and 4 hypokinetic at rest. Peak WMSI was 1.17 +/- 0.17 (p < 0.05 vs rest). Of the 12 patients with a positive DSE, 9 also showed diagnostic ECG changes and 6 complained of angina. Of the 10 patients with negative DSE, 5 had angina and 5 (one with angina) showed ECG changes. In 7 patients (7 segments) (32%), the location of dobutamine-induced wall motion abnormalities coincided with the area where exercise-induced hypoperfusion was observed with MIBI. CONCLUSIONS: More than a half of syndrome X patients with myocardial perfusion abnormalities also develop regional LV dysfunction during DSE. However, the site of perfusion defects and wall motion abnormalities can be different. Reversible ischemia, defined as a parallel limitation of flow reserve and inducible dysfunction, could be identified as the cause of chest pain in almost one-third of patients.     

Dobutamine stress echocardiography can predict reversible ventricular dysfunction after acute myocardial infarction

BACKGROUND: The aim of early treatment of acute myocardial infarction (AMI) is to achieve the rapid reperfusion of the culprit artery, which correlates with improvement in ventricular function and survival. With the widespread use of thrombolytic agents or coronary angioplasty as reperfusion strategies for AMI, it is possible to reduce the amount of myocardial necrosis. HYPOTHESIS: The assessment of residual viability with dobutamine stress echocardiography (DSE) in the infarcted area after AMI is relevant to subsequent management and prognosis. METHODS: Thirty-seven patients with AMI (mean age 59 +/- 12, 31 male, 22 with anterior AMI, 15 with inferior AMI) admitted to the coronary care unit within 3.8 +/- 1.8 h of the onset of symptoms were included. Two-dimensional echocardiography (2-D echo) study and DSE were performed at a mean of 4.7 +/- 1.8 days. Follow-up 2-D echo was performed at a mean of 25 +/- 11 days. To assess left ventricular regional systolic function, 2-D echo images were obtained at rest and during dobutamine-induced stress and were analyzed off-line according to the 13-segment model. Improvement in wall motion score (WMS) was defined by a decrease of at least two grades in the score. RESULTS: Wall motion score improved in 13 of the 37 patients after DSE (rest WMS 20.9 +/- 2.0 vs. D-WMS 17.7 +/- 2.2; p<0.001), which correlated with clinical or angiographic signs of reperfusion of the culprit vessel in all cases. Follow-up WMS evidenced a significant correlation with WMS after DSE (r = 0.91; p < 0.001). Sensitivity, specificity, and positive and negative predictive values of DSE in detecting patients whose left ventricular function (LVF) improved at 2-D echo follow-up were 72,96,92.8, and 82.7%, respectively. CONCLUSIONS: (1) Dobutamine stress echocardiography improved WMS in 35% of patients and correlated with signs of patency of the culprit vessel; (2) LVF improvement after dobutamine was predictive of late LVF recovery; (3) DSE can be a useful and safe tool for detecting reversible myocardial dysfunction after AMI.     

Comparison of dobutamine echocardiography and positron emission tomography in patients with chronic ischemic left ventricular dysfunction

Objectives. The aim of this study was to correlate dobutamine-induced contractile reserve as detected by echocardiography with findings on positron emission tomography in patients with chronic ischemic left ventricular dysfunction.

Background. Contractile reserve induced by low dose dobutamine infusion has been proposed as a marker of myocardial viability.

Methods. Sixty patients with stable coronary artery disease and left ventricular dysfunction (mean ejection fraction [± SD] 29 ± 10%) underwent transthoracic echocardiography with dobutamine infusion (up to 10 μg/kg body weight per min) and positron emission tomography with nitrogen-13 ammonia and fluorine-18 (F-18) fluorodeoxyglucose as a perfusion and a metabolic tracer, respectively. Regional wall motion, perfusion and metabolism were analyzed semiquantitatively by using a 16-segment model. Segments with F-18 fluorodeoxyglucose uptake > 50% were considered viable on positron emission tomography.

Results. After dobutamine infusion, hemodynamic variables changed significantly, and myocardial ischemia was evident in 17 patients. All 60 patients had dysfunctional myocardium considered viable on positron emission tomography (8 ± 4 segments/patient), whereas 52 patients had dysfunctional myocardium with contractile enhancement by dobutamine echocardiography (4 ± 2 segments/patient, P = 0.01). The extent of dysfunctional myocardium with contractile reserve appeared to correlate less closely with the total extent of viable dysfunctional myocardium identified by positron emission tomography than with the number of such segments associated with a pattern of perfusion-metabolism mismatch.

Conclusions. In patients with chronic ischemic left ventricular dysfunction, echocardiography can be used to identify enhancement in the contractile function of viable dysfunctional myocardium after infusion of low dose dobutamine. In this study, the presence and extent of such enhancement were relatively less than the values obtained from positron emission tomography.     

Einflu? der Bildqualit?t auf die Genauigkeit der nichtinvasiven Isch?miediagnostik mit der Dobutamin-Stre?magnetresonanztomographie im Vergleich zur Dobutamin-Stre?echokardiographie

The analysis of wall motion abnormalities with dobutamine stress echocardiography is an established method for the detection of myocardial ischemia. With ultrafast magnetic resonance tomography, the application of identical stress protocols as used for echocardiography is possible. In 208 consecutive patients (147 M, 61 F) with suspected coronary artery disease, dobutamine stress echocardiography partially using harmonic imaging and dobutamine stress magnetic resonance tomography (DSMR) were performed prior to cardiac catheterization. DSMR images were acquired during short breath holds in 3 short axis-, a 4-, and a 2-chamber view using a turbo gradient echo technique. Patients were examined at rest and during a standard dobutamine-atropine scheme until submaximal heart rate was reached. Regional wall motion was assessed in a 16 segment model. Significant coronary heart disease was defined as angiographic >/=50% diameter stenosis. With DSMR, significantly more patients yielded very good (69%) or good (13%) image quality in comparison with dobutamine stress echocardiography (20% and 31%, p<0. 05). Moderate image quality occurred in 16% with MR and 41% with dobutamine stress echocardiography (p<0.05), 2% and 8% were non-diagnostic. With each technique 18 patients could not be examined (DSE: emphysema: 10, adipositas: 8, DSMR: claustrophobia: 11, adipositas: 6, contraindication: 1). Four patients did not reach target heart rate. In 107 patients, significant coronary artery disease was found. With DSMR sensitivity was 88.7% (dobutamine stress echocardiography: 74.3%; p<0.05) and specificity 85.7% (dobutamine stress echocardiography: 69.8%; p <0.05). This difference was most pronounced in the group with moderate echocardiographic image quality. High dose DSMR is superior to dobutamine stress echocardiography and can replace this technique especially in patients with moderate echocardiographic image quality.