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.     

Prognostic role of dobutamine stress echocardiography in myocardial viability

PURPOSE OF REVIEW: The aim of this review is to provide a perspective on the role of dobutamine stress echocardiography to evaluate myocardial viability and assess prognosis in patients with ischemic left ventricular dysfunction. RECENT FINDINGS: Pooled analysis of currently available data demonstrates that dobutamine stress echocardiography provides useful information on recovery of dysfunctional but viable myocardium and prognosis. In fact, improvement of long-term prognosis may be the ultimate clinical challenge in the management of patients with ischemic left ventricular dysfunction. Dobutamine stress echocardiography can be used to assess residual ischemia and contractile reserve, which are significant determinants of prognosis. Additionally, other echocardiographic variables, such as end-diastolic wall thickness, end-systolic volume, and extent of viability, affect outcome after revascularization in patients with ischemic cardiomyopathy. SUMMARY: Dobutamine stress echocardiography provides information on myocardial ischemia, contractile reserve, and other prognostically relevant parameters in patients with ischemic left ventricular dysfunction. This information can be used to select the optimal treatment strategy for these patients and to estimate and improve clinical outcome.     

小剂量多巴酚丁胺超声心动图评价急性心肌梗死存活心肌的研究

目的　探讨梗死相关血管重建后存活心肌的功能恢复与左室重塑进程和左室功能恢复的关系。方法　将心肌梗死区异常室壁运动节段中存活心肌的节段数做为量化存活心肌的指标。筛选 4 8例初次急性心肌梗死患者 ,心肌梗死后 (2 0± 12 )天成功的接受梗死相关血管的介入治疗术 ,术前 1～ 3天接受静息超声心动图和小剂量多巴酚丁胺负荷超声心动图检查 ,术后 (5 4± 1 6 )个月复查静息超声心动图。依小剂量多巴酚丁胺超声心动图负荷试验检测出的梗死相关的异常室壁节段中存活心肌的节段数 ,将 4 8例患者分为 :Ⅰ组 ,大量存活心肌 (存活心肌节段≥ 6段 ) 11例 ,Ⅱ组 ,少量存活心肌 (2段≤存活心肌节段≤ 5段 ) 2 9例 ,Ⅲ组 ,无存活心肌 (存活心肌节段 <2段 ) 8例。分别测定术前和术后静息状态下的左室舒张末容积、左室收缩末容积、左室射血分数和左室室壁节段运动积分指数。结果　重建血管术后 (5 4± 1 6 )个月随访发现梗死相关动脉血管重建后 ,梗死相关血管的异常室壁运动有不同程度的改善 ,Ⅰ组的左室收缩末容量由 (6 3± 8)ml降至 (4 7± 10 )ml(P <0 0 1) ;室壁运动积分指数由 1 4± 0 2降至 1 1± 0 1(P <0 0 1) ,左室射血分数由 (4 6± 9) %增至 (5 7± 10 ) % (P<0 0 1)。Ⅱ组的左室收缩末容量 (7     

Safety of dobutamine stress transesophageal echocardiography in obese patients for evaluation of potential ischemic heart disease

The purpose of this study was to determine the safety of dobutamine stress transesophageal echocardiography (DS-TEE) in the evaluation of potential coronary artery disease in obese patients. Obese patients tend to have a higher prevalence of hypertension, coronary artery disease, and sleep apnea conditions that could potentially predispose to complications during endoscopic procedures such as DS-TEE. In addition, obese patients are more likely to have oxygen desaturation during upper gastrointestinal endoscopy. Thus, the safety of DS-TEE in 90 obese patients (body mass index (BMI) > or = 27.5 kg/m2) and 86 nonobese patients (BMI < 27.5 kg/m2) was compared. Minor complications (i.e., complications of transient duration and requiring no or only simple intervention) occurred with almost equal frequency in the nonobese and obese groups (28% vs. 29%, P = ns). Transient hypotension was observed in 9% of the obese group compared to 22% in the nonobese group (P < 0.025). However, transient hypertension was noted in 20% of the obese patients compared to 6% in the nonobese group (P < 0.01). A major complication occurred in three obese patients (3.3%), which included hypotension, marked elevation of systolic blood pressure, or ventricular fibrillation. Four patients (4.7%, P = ns) of the nonobese group had a major complication, which included sustained ventricular tachycardia in one, hypertension in one, and hypotension in two patients. No deaths occurred in either group. Although obesity should remain a consideration in the risk assessment of whether or not to perform DS-TEE, when proper precautions are instituted DS-TEE appears equally safe in obese as compared to nonobese patients.     

Assessment of myocardial viability in ischemic heart disease by cardiac magnetic resonance imaging

Assessment of myocardial viability aims at differentiating between viable and non-viable myocardium. The proof of dysfunctional but viable myocardium is crucial to predict outcome of revascularization after acute (AMI) and chronic myocardial infarction (CMI). Cardiac magnetic resonance imaging (CMRI) offers different options to detect viable myocardium: Measurements of end-diastolic wall thickness by cine-CMRI can be used to depict chronically scarred myocardium, but fails to detect acute myocardial necrosis. Low-dose dobutamine stimulation (LDDS) cine-CMRI analyses the contractile reserve of dysfunctional but viable myocardium under pharmacologic stimulus to identify viable myocardium in AMI and CMI with high specificity. Sensitivity of LDDS cine-CMRI is superior to LDDS echocardiography but reduced in patients with severely impaired left ventricular (LV) function. The delayed-enhancement (DE) technique directly visualises non-viable myocardium due to an altered contrast-media distribution in necrotic and fibrotic tissue. DE-CMRI identifies non-viable myocardium with high spatial resolution independently from LV function. The transmural extent of contrast enhancement in DE-CMRI is used to predict functional recovery after revascularization in AMI and CMI. Furthermore, the amount and pattern of contrast enhancement in DE-CMRI provide important prognostic information in both entities. Recent studies demonstrated the superiority of DE-CMRI compared to single photon emission tomography (SPECT) and positron emission tomography (PET) to assess myocardial viability. Therefore, DE-CMRI is currently recognised as the standard of reference for assessment of myocardial viability. The technical background, clinical application and accuracy of the different CMRI techniques to assess myocardial viability in AMI and CMI are discussed in this work.     

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     

Validation of viability assessment by electromechanical mapping by three-dimensional reconstruction with dobutamine stress echocardiography in patients with coronary artery disease

We evaluated the ability of electromechanical mapping (EMM) to discriminate between normal, viable, and nonviable (scarred) myocardium in patients with coronary artery disease versus dobutamine stress echocardiography (DSE) when the correspondence between the test and reference data sets is established via a common 3-dimensional reconstruction of the left ventricle. We studied 21 patients with coronary artery disease who underwent angiography, biplane ventriculography, and EMM within 1 month of DSE. A 3-dimensional left ventricular (LV) reconstruction was prepared from the ventriculogram and spatially aligned with EMM. EMM measurements of unipolar voltage, bipolar voltage, and local linear shortening were projected onto the three-dimensional left ventricle, averaged in each of 16 segments, and compared with DSE viability (normal, viable, scar) assessed at a core laboratory. All of the EMM measurements varied significantly (p <0.001) between the normal, viable, and scarred myocardium as assessed by DSE. Local linear shortening for normal, viable, and scarred segments was 10.4 +/- 6.5%, 7.8 +/- 5.6%, and 4.8 +/- 4.4%, respectively. In discriminating between these 3 groups, local linear shortening was more powerful than unipolar voltage or bipolar voltage (F = 20.765, F = 10.655, F = 4.795, respectively). Local linear shortening correlated best with viability, perhaps because it shares the same cognitive function as DSE. Three-dimensional analysis provides an anatomic framework that enables direct comparison of data from multiple imaging modalities rather than assuming segmental correspondence. Our results show that EMM provides significant on-line, diagnostic information on myocardial viability assessed by DSE on a segment-by-segment basis.     

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.     

Prognostic value of myocardial viability recognized by low-dose dobutamine echocardiography in chronic ischemic left ventricular dysfunction

This study assesses the prognostic value of myocardial viability recognized as a contractile response to inotropic stimulation in patients with left ventricular (LV) dysfunction in a large-scale prospective, multicenter, observational study. Four hundred twenty-five patients (mean age 61 +/- 10 years) with angiographically proven coronary artery disease, previous (>3 months) myocardial infarction, and severe LV dysfunction (ejection fraction <35%; mean 28 +/- 6%) were enrolled in the study. Each patient underwent low-dose dobutamine echocardiography (up to 10 microg/kg/min). Myocardial viability was identified as a rest-stress variation (Delta) in the wall motion score index (WMSI), in which each segment was scored from 1 = normal to 4 = dyskinetic in a 16-segment model of the left ventricle. Myocardial viability was identified as an improvement of >/=0.40 in WMSI. All patients were followed for a median of 3.1 years. One hundred eighty-eight were revascularized either by coronary artery bypass grafting (n = 118) or coronary angioplasty (n = 70). The only end point analyzed was cardiac death. In the revascularized group, cardiac death occurred in 4 of the 52 patients with and in 37 of the 136 patients without myocardial viability (7.7% vs 27.2%, p <0.003). Kaplan-Meier survival estimates showed a better outcome for those patients with compared to patients without myocardial viability who underwent coronary revascularization (90.1% vs 62%, p <0.0078). Thus, in severe LV ischemic dysfunction, myocardial viability by low-dose dobutamine echocardiography is associated with improved survival in revascularized patients.     

Assessment of myocardial viability with myocardial contrast echocardiography

The application of noninvasive imaging techniques to assess myocardial viability has become an important part of routine management of patients with acute myocardial infarction and chronic coronary artery disease. Information regarding the presence and extent of viability may help identify patients likely to benefit from revascularization or therapy directed at attenuating left ventricular remodeling. Myocardial contrast echocardiography (MCE) is capable of defining the presence and extent of viability by providing an accurate assessment of microvascular integrity needed to maintain myocellular viability. It is especially suited for the spatial assessment of perfusion, even when myocardial blood flow is reduced substantially in the presence of severe epicardial stenoses or in a bed dependent on collateral perfusion. The routine use of MCE to evaluate viability in patients with acute and chronic coronary artery disease is now feasible with the advent of new imaging technologies and microbubble agents capable of myocardial opacification from venous injections. The utility of this technique for determining treatment strategies has not been established but is forthcoming.     

QT dispersion correlates to myocardial viability assessed by dobutamine stress echocardiography in patients with severely depressed left ventricular function due to coronary artery disease

BACKGROUND: QT dispersion is prolonged in numerous cardiac diseases, representing a general repolarization abnormality. AIM: To evaluate the influence of viable myocardium on QT dispersion in patients with severely depressed left ventricular (LV) function due to coronary artery disease. METHODS AND RESULTS: 103 patients with ischemic cardiomyopathy (LV ejection fraction [EF]: 25+/-6%) were studied. Patients underwent 12-lead electrocardiography to assess QT dispersion, and two-dimensional echocardiography to identify segmental dysfunction. Dobutamine stress echocardiography (DSE) was then performed to detect residual viability. Resting echo demonstrated 1260 dysfunctional segments; of these, 476 (38%) were viable. Substantial viability (> or =4 viable segments on DSE) was found in 62 (60%) patients. QT dispersion was lower in these patients, than in patients without viability (55+/-17 ms vs. 65+/-22 ms, P=0.012). Viable segments negatively correlated to QT dispersion (r=-0.333, P=0.001). In contrast, there was no correlation between LVEF and QT dispersion (r=-0.001, P=NS). CONCLUSIONS: There is a negative correlation between QT dispersion and the number of viable segments assessed by DSE. Patients with severely depressed LV function and a low QT dispersion probably have a substantial amount of viable tissue. Conversely, when QT dispersion is high, the likelihood of substantial viability is reduced.     

Regional myocardial perfusion in ischemic heart disease assessed by myocardial contrast echocardiography

Myocardial contrast echocardiography is a new cardiovascular imaging technique that can be used to evaluate regional myocardial perfusion. Regional myocardial perfusion was studied in 12 patients with normal coronary arteries, 14 patients with old myocardial infarction, four patients with acute myocardial infarction, and 15 patients with effort angina. Conventional two-dimensional echo imaging was obtained during intracoronary injections of relatively small volumes (2 ml) of agitated Urografin-76. The echo intensities were measured before and after injecting contrast agents and the subtraction images were composed by a high-speed image processor (NEXUS 6400). Clear myocardial images were obtained in 10 of 12 the patients with normal coronary arteries, and they reflected well the epicardial arterial architecture by coronary angiography. In cases of old myocardial infarction, the infarcted areas appeared as contrast defects in seven and as slightly enhanced areas in three of the 10 patients. In cases of acute myocardial infarction, contrast defect areas in the myocardial images were less in two cases of successful early coronary thrombolysis or percutaneous transluminal coronary angioplasty (PTCA). However, contrast defects remained unchanged despite good recanalization in one case of delayed PTCA. In cases of effort angina, anginal attacks were successfully induced by rapid atrial pacing in six of the 15 patients. In four of the six patients, contrast enhancement in myocardial imaging during anginal attack decreased more in the endocardial than in the epicardial myocardium, possibly reflecting subendocardial ischemia. It is concluded that this technique can identify regional myocardial perfusion, which is not revealed by coronary angiography, and it is therefore useful for the clinical analysis of ischemic heart disease.     

Assessment of coronary artery disease by dobutamine stress echocardiography (DSE)

Background: Dobutamine stress echocardiography (DSE) is a new non-invasive imaging modality which combines two-dimensional echocardiography with cardiovascular stress induced by dobutamine infusion. Its use in patients with suspected or documented coronary artery disease (CAD) is currently under extensive investigation. Aims: To illustrate the clinical utility, safety and diagnostic value of DSE. Methods: One hundred and thirty-seven consecutive patients referred for DSE were studied. Eighty-four patients also underwent coronary angiography. Results: Eleven patients (8%) did not undergo DSE because of poor image quality. Of the remaining 126 patients, 110 (87%) achieved their target heart rate or reached a pre-determined end point during DSE. Eight patients (6%) developed non-cardiac side effects during DSE, none of which required premature termination of the procedure. Cardiac arrhythmias were documented in 15 patients (12%) but only one required intervention. In 84 patients who underwent coronary angiography, DSE showed a sensitivity and specificity of 88% and 83%, respectively, in detecting the presence of, and 75% and 75%o, respectively, in localising significant CAD. In 35 patients who underwent DSE after uncomplicated myocardial infarction, the positive and negative predictive values for cardiac events following infarction in a six-month follow up period were 74% and 62%, respectively. Conclusions: DSE is a well tolerated, safe and useful test in detecting and localising significant CAD. It can also provide useful post-infarctional prognostic information. (Aust NZ J Med 1995; 25: 707-715.) Key words: Echocardiography, dobutamine, coronary artery disease.     

Evaluation of regional myocardial function in ischemic heart disease by echocardiography

Echocardiography can display motion abnormalities of acutely or chronically ischemic myocardium. In experimental studies, this permits the evaluation of the effect on regional dyskinesis of potentially therapeutic interventions. In clinical studies, the demonstration of segmental dyskinesis has been primarily useful for diagnostic purposes. As more experience is gained with the newer two-dimensional cross-sectional ultrasound techniques, it appears likely that these will afford a major advance in the diagnosis of ischemic heart disease by permitting the routine noninvasive demonstration of segmental ventricular dyskinesis and assessment of regional myocardial function.     

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.     

Prognostic value of myocardial viability and ischemia detected by dobutamine stress echocardiography early after acute myocardial infarction treated with thrombolysis

Objectives. The aim of the study was to assess the prognostic value of myocardial viability and ischemia detected by dobutamine stress echocardiography (DSE) in patients with acute myocardial infarction (AMI) treated with thrombolysis.Background. DSE can detect myocardial viability and ischemia early after AMI, but the prognostic importance of viability and ischemia in these patients has yet to be assessed.Methods. DSE was performed in 152 patients at a mean of 9 ± 5 days after a first AMI treated with thrombolysis to evaluate myocardial viability and ischemia. The patients were followed up for 15 ± 19 months.Results. On the basis of DSE results three groups of patients were identified: group 1 (95 patients, 62.5%) with myocardial viability and ischemia, group 2 with myocardial viability without ischemia (32 patients, 21%) and group 3 (25 patients, 16.5%) with no myocardial viability. During follow-up 10 patients (6.5%) had hard events, 53 (35%) developed unstable angina and 67 (44%) underwent myocardial revascularization. The rate of hard events was 10% in group 1 and 0% in group 2 and 3 patients (p < 0.05 group 1 versus group 2); group 1 patients with viability and ischemia showed a significantly higher rate of recurrence of unstable angina and myocardial revascularization procedures (40% and 60%) compared to group 2 (22% and 16%) and group 3 patients (20% and 20%). Using the Cox multivariate stepwise model, only the extent of ischemic myocardium (hazard ratio (HR) = 21.7, p = 0.02) and angina during DSE (HR = 4.45, p = 0.03) were significant predictors of hard events; an ischemic response to DSE (HR = 2.92, p = 0.001) was the most important predictor of spontaneous events, followed by ST-segment depression during DSE (HR = 1.71, p = 0.04), angina during DSE (HR = 1.53, p = 0.19) and age (HR = 0.96, p = 0.05).Conclusions. In patients with a first AMI treated with thrombolysis the presence and extent of myocardial ischemia during DSE is the most important predictor of both hard and spontaneous cardiac events, whereas myocardial viability does not have an independent prognostic value.