Role of real-time myocardial contrast echocardiography in the assessment of viability after acute myocardial infarction and angioplasty.

OBJECTIVE: To assess the role of myocardial contrast echocardiography (MCE) in early identification of myocardial viability in patients with residual segmental dysfunction after myocardial infarction and primary angioplasty (PA), in comparison with dobutamine stress echocardiography (DSE), using late functional recovery as gold standard. DESIGN: Prospective study for comparison of the two methods. SETTING: Hospital. PATIENTS: 17 patients (11 male, 53 +/- 11 years old) were consecutively included, with a first myocardial infarction and PA, with residual segmental akinesis or dyskinesis and good echocardiographic window. METHODS: All patients underwent: a) baseline echocardiographic study, MCE, and DSE obtained at 4.0 +/- 1.2 days after PA; b) late echocardiographic study performed at 4.4 +/- 0.8 months after PA. MCE was performed with Optison, administered as a slow infusion via a peripheral vein and a modality of real-time perfusion imaging with power pulse inversion and flash and subsequent data acquisition of triggered end-systolic images. Segmental contractility and perfusion were assessed using a 16-segment model. Perfusion assessment was qualitative (three perfusion patterns) and quantitative (ratio of maximal intensity between dysfunctional segments and contralateral normal segments). The viability criterion for MCE was defined as homogenous enhancement in 50% of wall thickness in each segment. The standard criterion for myocardial viability was defined as late functional recovery. 6. RESULTS: Viability was present in 56 (63.6%, Group 1) of dysfunctional segments and was absent in the remaining 32 (36.4%, Group 2). The sensitivity of DSE for viability was 80.0%, while specificity was 86.5%. The positive and negative predictive values were, respectively, 91.8% and 69.6%. MCE yielded a sensitivity of 96.5% and specificity of 78.1%, while positive and negative predictive values were respectively 86.2% and 94.1%. With the two methods together, the positive predictive value was 90.3% and negative was 80.0%. The intensity ratio was higher for viable segments (Group 1) in comparison with non-viable ones (Group 2; p<0.005). 7. CONCLUSIONS: This study showed a potentially valuable role for MCE in assessing viability in patients with myocardial infarction and PA. In comparison with DSE, MCE yielded a higher negative predictive value as well as a high positive predictive value. The use of both methods together is promising as a useful tool for early assessment of viability after primary angioplasty.     

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.     

Integrated backscatter for the assessment of myocardial viability

PURPOSE OF REVIEW: Ultrasonic tissue characterization is a non-invasive diagnostic method that uses myocardial integrated backscatter analysis to determine contractile performance and myocardial viability independent of wall motion. This review discusses recent clinical findings regarding the application of ultrasonic tissue characterization for the assessment of myocardial viability. RECENT FINDINGS: As this technique is non-invasive, ultrasonic tissue characterization can be used to predict the patency of infarct-related arteries in patients in the early stage of acute myocardial infarction. Several recent studies have shown that this technique is useful in identifying myocardial contractile reserve. The accuracy of ultrasonic tissue characterization for predicting functional recovery after coronary reperfusion is comparable to dobutamine echocardiography and radionuclide methods. Several studies have suggested that the cyclic variation of myocardial integrated backscatter reflects myocardial viability rather than contractile reserve. The cyclic variation of integrated backscatter is associated with myocardial viability confirmed by the integrity of the microvasculature identified by contrast echocardiography. In addition, the cyclic variation of integrated backscatter better reflects myocardial viability confirmed by the integrity of cellar metabolism than contractile reserve. SUMMARY: Ultrasonic tissue characterization with integrated backscatter is a useful non-invasive method that can provide unique information for the assessment of myocardial viability.     

Prediction of the no-reflow phenomenon with ultrasonic tissue characterization in patients with anterior wall acute myocardial infarction

The no-reflow phenomenon after acute myocardial infarction seems to be related to ischemic injury before reperfusion. Analyzing cardiac cycle-dependent variation of integrated backscatter (IBS) is a unique method to assess myocardial viability. In this study, the ability of ultrasonic tissue characterization with IBS to predict the no-reflow phenomenon was investigated in 90 patients with first anterior wall infarction who underwent successful primary percutaneous coronary intervention. IBS images were recorded on admission (before reperfusion), and the magnitude of the cyclic variation of IBS within the infarct zone was expressed as phase-corrected magnitude (PCM) by giving positive and negative values when it showed synchronous and asynchronous contraction, respectively. Myocardial contrast echocardiography was performed soon after reperfusion, and 21 patients showed substantial no-reflow. They had smaller PCM before reperfusion than patients without no-reflow (-1.6 +/- 1.9 vs 0.7 +/- 2.7 dB, respectively; p = 0.0002). Multivariate logistic regression analysis revealed that PCM before reperfusion and the number of Q waves were the independent predictors of no reflow. Using -1.0 dB as the cut-off point, PCM predicted no reflow with 66.7% sensitivity and 81.2% specificity. These results indicate that the analysis of myocardial IBS could predict the no-reflow phenomenon before reperfusion.     

Comparison of simultaneous dobutamine echocardiography and thallium-201 stress-reinjection single-photon emission computed tomography in predicting improvement of chronic myocardial dysfunction after revascularization

Previous studies have shown that ultrasonic integrated backscatter is valuable in characterizing stunned myocardium. Recent investigations have demonstrated that resting cardiac cycle-dependent variation of integrated backscatter closely paralleled the contractile reserve in patients with chronic left ventricular ischemic dysfunction. The purpose of this study was to validate whether ultrasonic tissue characterization (UTC) compared with dobutamine stress echocardiography (DSE) and thallium-201 stress-reinjection single-photon emission computed tomography (Tl-SPECT) could predict reversible myocardial dyssynergy in patients with chronic coronary artery disease. Forty-eight patients with stable coronary artery disease underwent UTC, DSE, and Tl-SPECT simultaneously before successful coronary revascularization and were followed up with echocardiograms at rest >3 months later. Among the 58 investigated segments, the weighted amplitude, a composite parameter derived from the integrated backscatter power curve, was larger for those groups with greater functional recovery (p <0.001). For the persistent akinetic segments, the weighted amplitudes were small with large deviations of the nadir ratios that represented the asynchrony between the intramural contractile events and the global systole. Using the cut-off value 2.0 of the weighted amplitude, the sensitivity and specificity for predicting functional improvement after revascularization were both 82.8% (kappa = 0.66) and comparable to the sensitivity and specificity of DSE and Tl-SPECT. UTC, delineating the myocardial physical state and intramural contraction, can be a novel approach in predicting functional improvement of chronic dyssynergy after revascularization.     

小剂量多巴酚丁胺超声心动图联合心肌声学造影对心肌梗死后存活心肌的诊断价值

目的前瞻性评价小剂量多巴酚丁胺超声心动图(LDDE)联合心肌声学造影(MCE)对心肌梗死后存活心肌的诊断价值。方法对24例心肌梗死者进行静态MCE、LDDE及3个月后静态超声心动图随访分析。MCE和室壁运动均用16段划分法进行目测半定量计分。心肌造影计分(MCS)回声均匀性增强为1分,回声低淡不均匀为0.5分,缺损为0分。室壁运动计分(WMS)用常规计分法。结果随访时,运动改善的心肌节段中MCS1分占49.4%、0.5分占50.6%,对LDDE均有反应;运动无改善的节段MCS0.5分占9.5%,0分占90.5%,对LDDE有反应者占13.3%,无反应占86.7%。预测存活心肌的敏感性、特异性及准确率分别为LDDE86%、86.7%、86.4%;MCE100%、89.7%、94.6%;LDDE联合MCE86.1%、100%、94.0%。结论心肌微血管结构与功能的完善是心肌存活的基本条件。MCE灌注正常和低灌注,且对多巴酚丁胺有反应的心肌有收缩力储备;而对多巴酚丁胺无反应的低灌注或无灌注心肌则多不能恢复收缩功能。LDDE联合MCE能提高检测存活心肌的特异性及准确率。     

静息与负荷心肌造影超声心动图识别存活心肌的对比研究

目的探讨负荷心肌造影超声心动图(MCSE)对心肌梗死后存活心肌评价的疗效和安全性。方法选择冠状动脉造影证实的心肌梗死患者30例。首先在静息状态下行心肌造影超声心动图(MCE),MCE心肌灌注结果采用半定量评价。多巴酚丁胺负荷静脉滴注剂量分别为5、10、20μg·kg~(-1)·min~(-1),每期3 min观察心率、血压变化于达到负荷剂量后再次行MCE,并以~(18)F-脱氧葡萄糖正电子发射计算机体层扫描(PET)作为金标准评价其敏感性和特异性。结果 MCE总共评价360个梗死节段,静息MCE评价1、0.5、0分为264、22、74个节段。多巴酚丁胺负荷MCSE评价1、0.5、0分为286、30、44个节段,评价MCE敏感性和特异性分别为38.10%、88.89%,kappa=0.285(P0.01)。评价MCSE敏感性和特异性分别为86.21%、88.89%,kappa=0.746(P0.05)。结论MCE及MCSE安全性良好。MCE及MCSE均与冠状动脉造影心肌梗死部位有较好的相关性,以PET作为金标准,MCSE具有较高的敏感性和特异性,是评价梗死节段内存活心肌的较好方法。     

经静脉心肌声学造影评价心肌梗死后存活心肌的价值

目的　探讨经静脉心肌声学造影 (MCE)对心肌梗死后存活心肌的诊断价值。方法　 2 4例心肌梗死患者用二维超声评价室壁运动情况 ,同时经静脉进行MCE ,以 3个月后静态超声心动图左室心肌节段性运动改善为依据评价MCE对心肌梗死后存活心肌的诊断价值。结果　在 2 4例病人的 384个心肌节段中 ,运动异常节段 184个。在运动异常的 184个节段中 ,MCE1分 39段 ,0 5分 5 0段 ,0分 95段。 3个月复查 79个节段有运动改善 ,其中 39段来自MCE1分的心肌 ,4 0段来自MCE0 5分的心肌。MCE对预测心肌梗死后室壁运动改善的敏感性、特异性、阳性预测值、阴性预测值及准确率分别为 :10 0 %、89 7%、84 8%、10 0 %和 94 6 %。结论　MCE能比较准确地预测心肌梗死后心肌的存活性     

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.     

Myocardial viability after primary coronary angioplasty: low-dose dobutamine stress echocardiography versus myocardial contrast echocardiography.

BACKGROUND: Successful reperfusion therapy in patients with acute myocardial infarction (AMI) improves survival. Indeed, after AMI myocardial dysfunction may be reversible (hibernating or stunned myocardium). Low-dose dobutamine stress echocardiography (LDDSE) provides us with the possibility of evaluating viable myocardial segments, while myocardial contrast echocardiography (MCE) allows the study of the microcirculation in the same myocardial areas. The aim of our study was to compare LDDSE and MCE, in the prediction of the recovery of segments in patients with AMI who were submitted to primary coronary angioplasty (PTCA). METHODS: We studied 14 patients with AMI. Both LDDSE and MCE with Levovist were performed after primary PTCA. The viability gold standard was a recovery of contractility detected at echocardiography 2 months later. RESULTS: For LDDSE, the sensitivity was 91%, the specificity 71% and the positive and negative predictive values were 93 and 64% respectively. For MCE, the sensitivity was 94%, the specificity 44%, the positive predictive value 89%, and the negative predictive value 59%. Two tests agreed in 81% of the cases. Stress echocardiography and contrast echocardiography agreed in 81% of cases. CONCLUSIONS: LDDSE has a very good positive accuracy, it has an acceptable negative predictive value and is relatively cheap. On the other hand, MCE has a good positive accuracy, but a low negative accuracy and carries a high cost. The integration of these two tests, which are too expensive in clinical practice, could improve our comprehension of the post-PTCA pathophysiology.     

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.     

Clinical significance of perfusion techniques utilising different physiological mechanisms to detect myocardial viability: a comparative study with myocardial contrast echocardiography and single photon emission computed tomography

Myocardial uptake using (99m)Tc-sestamibi single photon emission computed tomography (SPECT) depends largely on myocardial microvascular volume. Myocardial contrast echocardiography (MCE) is a relatively new technique that detects not only microvascular volume but also blood flow. These differing mechanisms may affect the relative accuracies of MCE and SPECT for detecting myocardial viability (MV) early after acute myocardial infarction (AMI) and thrombolysis. Accordingly 56 patients underwent resting transthoracic echocardiography, low-power MCE and SPECT 7+/-2 days following first AMI and thrombolysis. Contractile reserve (CR) was assessed 3 months following revascularization. The sensitivity and specificity of MCE and SPECT were 83% and 78% (p=ns) and 78% and 45% (p<0.01) respectively. MCE was the only multivariate predictor of global recovery of function and CR (OR=3.5, p=0.01). The different physiological mechanisms employed by MCE and SPECT translate into different relative accuracies for the detection of MV.     

Comparison of acoustic densitometry and dobutamine echocardiography for an assessment of myocardial viability

AIM: The aim of this study has been to compare acoustic densitometry and dobutamine echocardiography for an assessment of myocardial viability. METHODS AND RESULTS: Thirty-four patients with coronary artery disease and dysfunctional myocardial segments, who were referred for myocardial revascularization, underwent a viability assessment using low-dose dobutamine echocardiography and acoustic densitometry. Results of the two techniques were compared to follow-up resting echocardiography. This follow-up examination was performed at a mean of 3 months after successful revascularization in order to assess the recovery of function in revascularized, initially dysfunctional segments. Echocardiography was performed in standard views using 16-segment model of the left ventricle. Viable myocardium was identified by the augmentation of systolic thickening of an abnormal segment by at least one grade during dobutamine infusion and by the value of the maximal amplitude of cyclic variation of integrated backscatter. Acoustic densitometry had the sensitivity and specificity to predict functional recovery 90% and 77%, respectively. Dobutamine echocardiography had the sensitivity and specificity to predict contractile reserve 83% and 81%, respectively. The results were statistically comparable. Concordance between these methods was 80%. CONCLUSION: Acoustic densitometry and dobutamine echocardiography did not statistically differ in the prediction of functional recovery dysfunctional myocardial segments after revascularization.     

Prediction of functional recovery of viable myocardium after delayed revascularization in postinfarction patients: accuracy of dobutamine stress echocardiography and influence of long-term vessel patency.

OBJECTIVES: We sought to evaluate dobutamine stress echocardiography (DSE) for predicting recovery of viable myocardium after revascularization with cineangiography as a gold standard for left ventricular (LV) function. We studied the influence of late vessel reocclusion on regional LV function. BACKGROUND: Dobutamine stress echocardiography is a well established evaluation method for myocardial viability assessment. In previous studies the reference method for assessing LV recovery was echocardiography, long-term vessel patency has not been systematically addressed. METHODS: Sixty-eight patients with a first acute myocardial infarction (AMI) and residual stenosis of the infarct related artery (IRA) underwent DSE (mean +/- standard deviation) 21 +/- 12 days after AMI to evaluate myocardial viability. Revascularization of the IRA was performed in 54 patients by angioplasty (n = 43) or bypass grafting (n = 11). Coronary angiography and LV cineangiography were repeated at four months to assess LV function and IRA patency. RESULTS: Sensitivity and specificity of DSE for predicting myocardial recovery after revascularization were 83% and 82%. In the case of late IRA patency, specificity increased to 95%, whereas sensitivity remained unchanged. In the 16 patients with myocardial viability and late IRA patency, echocardiographic wall motion score index decreased after revascularization from 1.83 +/- 0.15 to 1.36 +/- 0.17 (p = 0.0001), and left ventricular ejection fraction (LVEF) increased from 0.52 +/- 0.06 to 0.57 +/- 0.06 (p = 0.0004), whereas in five patients, reocclusion of the IRA prevented improvement of segmental or global LV function despite initially viable myocardium. CONCLUSIONS: Dobutamine stress echocardiography is reliable to predict recovery of viable myocardium after revascularization in postinfarction patients. Late reocclusion of the IRA may prevent LV recovery and influence the accuracy of DSE.     

Comparison between contrast echocardiography and magnetic resonance imaging to predict improvement of myocardial function after primary coronary intervention

The relative merits of myocardial contrast echocardiography (MCE) and magnetic resonance imaging (MRI) to predict myocardial function improvement after percutaneous coronary intervention have not been evaluated until now. We studied 35 consecutive patients with acute myocardial infarction who underwent percutaneous coronary intervention using MCE and MRI and first-pass imaging for evaluation of myocardial perfusion. Delayed-enhanced MRI was included as another method to differentiate viable from infarcted tissue. MCE was performed by power modulation and intravenous Sonovue. A 16-segment model of the left ventricle was used to analyze all myocardial contrast echocardiograms and magnetic resonance images. At 60 days of follow-up, MCE showed improvement of function in 115 of 192 (60%) dysfunctional segments. The sensitivity, specificity, and accuracy for the prediction of functional improvement were comparable among MCE (87%, 90%, and 88%), first-pass MRI (87%, 60%, and 79%), and delayed-enhancement MRI (75%, 100%, and 82%, respectively, all p = NS). In conclusion, MCE and MRI allowed for prediction of myocardial function improvement after percutaneous coronary intervention. MCE had a comparable accuracy and, as a bedside technique, may be an alternative tool in the acute phase of acute myocardial infarction.     

Serial evaluation of perfusion defects in patients with a first acute myocardial infarction referred for primary PTCA using intravenous myocardial contrast echocardiography.

AIMS: To investigate whether myocardial contrast echocardiography using Sonazoid could be used for the serial evaluation of the presence and extent of myocardial perfusion defects in patients with a first acute myocardial infarction treated with primary PTCA, and specifically, (1) to evaluate safety and efficacy of myocardial contrast echocardiography to detect TIMI flow grade 0--2, (2) to evaluate the success of reperfusion and (3) to predict left ventricular recovery after 4 weeks follow-up. METHODS AND RESULTS: Fifty-nine patients underwent serial myocardial contrast echocardiography, immediately before primary PTCA (MCE1), 1 h (MCE2) and 12--24 h after PTCA (MCE3). A perfusion defect was observed in 21 of 24 patients (88%) with anterior acute myocardial infarction. All but one had TIMI flow grade 0--2 prior to PTCA. Nine of 31 patients (29%) with inferior acute myocardial infarction showed a perfusion defect and all had TIMI flow grade 0-2 prior to PTCA. Restoration of TIMI flow grade 3 was achieved in 73% of the patients by primary PTCA. A reduction in size of the initial perfusion defect of at least one segment (16 segment model) or no defect vs persistent defect in patients with anterior acute myocardial infarction was associated with improved global left ventricular function at 4 weeks; mean global wall motion score index 1.29+/-0.21 vs 1.66+/-0.31 (P=0.009). Multiple regression analysis in patients with an anterior acute myocardial infarction revealed that the extent of the perfusion defect at MCE3 was a significant (P=0.0005) independent predictor for left ventricular recovery at 4 weeks follow-up. The only other independent predictor was TIMI flow grade 3 post PTCA (P=0.007). CONCLUSION: Intravenous myocardial contrast echocardiography immediately prior to primary PTCA seems safe and is capable of detecting the presence of a perfusion defect and its subsequent dynamic changes, particularly in patients with a first anterior acute myocardial infarction. A significant reduction in size of the initial perfusion defect using serial myocardial contrast echocardiography predicts functional recovery after 4 weeks and these findings underscore the potential diagnostic value of intravenous myocardial contrast echocardiography.     

Relationship between late potentials and myocardial viability assessed by dobutamine echocardiography in the early postinfarction period

BACKGROUND: In the postmyocardial infarction period, late potentials (LPs) are a sensitive marker for the occurrence of sustained ventricular tachycardia and ventricular fibrillation. The relationship between positive signal-averaged electrocardiogram (SAECG) and myocardial viability remains controversial. The aim of the present study was to assess prospectively the possible relationship between LPs and myocardial viability detected by dobutamine stress echocardiography (DSE) in the early period after myocardial infarction (AMI), before hospital discharge. DESIGN: Ninety-nine patients with AMI were included prospectively in the study. The mean age was 58 +/- 11 years, 17 were women and 82 were men. All patients had SAEG and DSE, and 94 had coronary angiography before hospital discharge. RESULTS: In the overall population, presence of viability was demonstrated in fewer patients with LPs [37 of 70 (52%)] than absence of viability [18 of 29 (62%)] but the difference did not reach statistical significance. In the subgroup of patients with left ventricular ejection fraction (LVEF) lower than 40%, at higher risk of arrhythmias, the presence of viability was associated with the absence of LPs: 80% of the patients without LPs had viability by DSE (P < 0.01) and only 35% of patients with LPs had viability by DSE (not significant). CONCLUSIONS: In patients with an acute myocardial infarction and with low ejection fraction (<40%), the absence of LPs is related to the presence of viable myocardium as assessed by DSE early after the acute event. These data also suggest that myocardial viability is not the substrate for LPs in this population.     

Assessment of myocardial viability using myocardial contrast echocardiography

Myocardial contrast echocardiography (MCE) is a technique that uses microbubbles as a tracer during simultaneous ultrasound of the heart. The microbubbles can be used to provide quantitative information regarding the adequacy of myocardial blood flow (MBF), as well as the spatial extent of microvascular integrity. In acute myocardial infarction, MCE can identify the presence of collateral flow within the risk area, and can therefore predict preservation of myocardial viability and ultimate infarct size even prior to reperfusion. After reperfusion, the extent of microvascular no-reflow can be determined, and has significant implications for recovery of left ventricular function. In chronic ischemic heart disease, MCE has also been shown to successfully differentiate viable from necrotic myocardium. This technique can accurately predict recovery of function after revascularization. More importantly, MCE can be used to identify viable segments that may help to prevent infarct expansion and remodeling, and thus improve patient outcomes.     

Comparison of two- versus three-dimensional myocardial contrast echocardiography for assessing subendocardial perfusion abnormality after percutaneous coronary intervention in patients with acute myocardial infarction

Myocardial contrast echocardiography (MCE) visualizes myocardial perfusion abnormalities after acute myocardial infarction. However, the limited view of 2-dimensional echocardiography reduces its ability to estimate perfusion abnormalities, especially in the subendocardial region. Three-dimensional echocardiography provides images of the left ventricular endocardium directly. This study was conducted to evaluate the ability of 3-dimensional MCE to assess abnormalities of subendocardial perfusion. Intracoronary 2- and 3-dimensional MCE was performed after primary percutaneous coronary intervention in 47 patients with acute myocardial infarction. Myocardial perfusion within the risk area was evaluated as good, poor, or no reflow on 2-dimensional MCE or as good, poor, or no myocardial opacification in endocardium on 3-dimensional MCE. The 2 methods showed different distributions of perfusion patterns: good, poor, and no reflow on 2-dimensional MCE in 31 (66%), 9 (19%), and 7 (15%) patients and good, poor, and no myocardial opacification in endocardium on 3-dimensional MCE in 17 (36%), 16 (34%), and 14 (20%) patients, respectively. Although only 19 patients (61%) with good reflow on 2-dimensional MCE showed myocardial perfusion grade 3 on angiography, 16 of 17 patients (94%) with good myocardial opacification in endocardium on 3-dimensional MCE showed myocardial perfusion grade 3. Although there were no significant differences in peak creatine kinase among the 3 subsets classified by 2-dimensional MCE, peak creatine kinase showed significant differences not only among the 3 groups but also among the subsets classified by 3-dimensional MCE. Classification by 3-dimensional MCE also predicted regional wall motion after 4.6 +/- 2.7 months, with significant differences between each pair of groups, whereas there was significant overlap of these values between the group with poor reflow and other 2 groups by 2-dimensional MCE. In conclusion, 3-dimensional MCE is a feasible way to assess subendocardial perfusion and predicts infarct size and functional recovery more precisely than 2-dimensional MCE.     

急性心肌梗死超急性期的超声诊断

目的 研究急性心肌梗死(AMI)超急性期时的心肌组织超声背向散射积分(IBS)的变化及对临床诊断AMI超急性期的价值.方法 将72例AMI患者分成2组:超急性期组(梗死时间在2 h以内)30例,急性期组42例(梗死时间>2 h,有典型的心电图改变);另取正常对照组30例.用HP-5500型超声诊断仪,分别测量心肌梗死区域和非梗死区域心肌组织的心动周期时间平均背向散射积分(IBS),并将其与心包IBS的比值作为心肌IBS的校正值(IB%),舒张末期与收缩末期的IBS差值即IBS的周期变化幅度(CVIB),并将其与心包IBS的比值作为心肌CVIB的校正值(CVIB%).同时作心电图的比较对照.结果 当AMI超急性期组患者心电图还无典型变化时,心肌梗死部位的IBS值已明显大于正常人[(18.8±3.4)dB比(8.3±1.2)dB,P<0.01],而CVIB明显小于正常人[(6.3 ±0.7)dB比(7.6±1.1)dB,P<0.01].急性期组患者,其IBS明显高于正常人及患者本身非心肌梗死部位[(22.2±4.1)dB比(8.3±1.2)dB,(21.1±3.2)dB比(8.7 ±0.9)dB,P<0.01],而CVIB则明显低于正常人及患者本身非心肌梗死部位[(5.6±0.8)dB比(7.6±1.1)dB,P<0.05;(5.8±0.7)dB比(9.3±0.9)dB,P<0.01].且与心电图的变化完全一致.结论 心肌组织背向散射积分对临床上诊断AMI超急性期有很高的价值,并可判断病变心肌的范围和功能状况.