ST-segment elevation during dobutamine stress testing predicts functional recovery after acute myocardial infarction

OBJECTIVES: The aims of this study were (1) to assess the relation between ST-segment elevation and wall motion response occurring during dobutamine testing and (2) to evaluate the usefulness of stress-induced ST-segment elevation for predicting functional recovery after acute myocardial infarction. BACKGROUND: Clinical significance of stress-induced ST-segment elevation after acute myocardial infarction remains controversial. According to previous studies, it may reflect a larger infarcted area, depressed left ventricular function, left ventricular aneurysm, stress-induced dyskinesia, residual myocardial ischemia, or viability in the affected region. Whether transient ST-segment elevation occurring during dobutamine testing may predict functional recovery is unknown. METHODS AND RESULTS: We studied 38 patients who underwent dobutamine stress testing early (5 +/- 2 days) after a first acute myocardial infarction. Dobutamine was infused at increasing doses from 5 to a maximum of 40 microg/kg per minute, with the addition of up to 1 mg of atropine if the target rate could not be reached by dobutamine alone. Twelve-lead electrocardiography and cross-sectional echocardiography were continuously monitored throughout the test. Dobutamine-induced ST-segment elevation was defined as a new or worsening >/=1 mm elevation, 80 ms after J point, in >/=2 infarct-related leads. Quantitative angiography was available in all patients before hospital discharge. Follow-up resting echocardiography was recorded in all patients 12 to 18 months after the acute event. ST-segment elevation was observed in 20 of the 38 patients. There were no significant differences between patients with and those without dobutamine-induced ST-segment elevation in age, site of infarction, peak level of total creatine kinase enzyme, and use of thrombolytic therapy, angioplasty, or both. Persistent akinesis without change during dobutamine stress testing was more frequently observed in patients without ST elevation (P <. 05). A biphasic response during dobutamine testing was more frequently observed in patients with ST-segment elevation (P =.01). Multivariate analysis selected 2 independent variables associated with ST-segment elevation: a biphasic response during dobutamine stress (chi-square = 7.3; P =.007) and the minimal lumen diameter of the infarct-related vessel at quantitative angiography (chi-square = 5.5; P <.02). Functional recovery was demonstrated in 26 patients. Sensitivity of ST-segment elevation for the prediction of functional recovery was 69%, specificity 83%, positive predictive value 90%, and accuracy 74%. Two independent variables predicting functional recovery were selected: dobutamine-induced ST-segment elevation (chi-square = 9.1; P =.003) and a biphasic response during stress (chi-square = 6.15; P =.013). CONCLUSIONS: Dobutamine-induced ST-segment elevation in the infarct-related leads is an ancillary sign of viable myocardium in jeopardy. It has a high specificity and an acceptable sensitivity for the prediction of functional recovery after acute myocardial infarction.     

Detection of functional recovery using low-dose dobutamine and myocardial contrast echocardiography after acute myocardial infarction treated with successful thrombolytic therapy

OBJECTIVE: We studied the value of low-dose dobutamine stress echocardiography (LDDE) and myocardial contrast echocardiography (MCE) in early prediction of left ventricular functional recovery (LVFR) after acute myocardial infarction (AMI) treated with successful thrombolysis. DESIGN: LDDE and MCE using second-harmonic intermittent imaging were performed in first week after AMI. LVFR was defined as an absolute > or =5% increase in ejection fraction, from early to 6 months of follow-up by Technetium-99m-Sestamibi single-photon emission computed tomography. PATIENTS: Out of 50 patients studied, 19 evolved with LVFR (group 1) and 31 without LVFR (group 2). Regional dysfunction was detected in 103 (37%) infarcted-related segments in group 1 and in 173 (63%) segments in group 2. RESULTS: Sensitivity, specificity, positive, and negative predictive values and accuracy for detecting LVFR by LDDE were 94.7% (18/19), 87.1% (27/31), 81.8% (18/22), 96.4% (27/28), and 90% (45/50), respectively, and by MCE were 94.7% (18/19), 51.6% (16/31), 54.5% (18/33), 94.1% (16/17), and 68% (34/50). In group 1, functional improvement was observed in 86.9% (53/61) of segments with contractile reserve by LDDE and in 65.8% (52/79) of segments with microvascular perfusion by MCE. In group 2, functional improvement was observed in 78.3% (18/23) of segments with contractile reserve by LDDE and in 25.5% (25/98) of segments with microvascular perfusion by MCE. All segments without perfusion by MCE evolved without functional recovery. CONCLUSION: LDDE was an accurate predictor of late left ventricular function recovery after AMI, while MCE was sensitive and has a high negative predictive value demonstrating that microvascular perfusion is essential for LVFR.     

Comparison of intravenous myocardial contrast echocardiography and low-dose dobutamine echocardiography for predicting left ventricular functional recovery following acute myocardial infarction

Akinesia after acute myocardial infarction (AMI) may be reversible or irreversible. Distinguishing these 2 entities early after AMI is difficult, but clinically important. Previous studies have shown that myocardial contrast echocardiography (MCE) and low-dose dobutamine echocardiography (DE) may both be useful in this setting. However, there are few data regarding the relative and combined value of these techniques. The aim of this study was to compare the utility of real-time intravenous MCE and low-dose DE in the early prediction of functional recovery of akinetic myocardium after AMI. Thirty-seven patients were studied 3 +/- 2 days after an AMI. Each subject underwent real-time MCE using an intravenous infusion of perflutren microbubbles. Immediately after this, low-dose DE was performed. Contrast opacification and wall motion were determined by experienced observers blinded to clinical data. Repeat echocardiograms were obtained 51 +/- 19 days later and wall motion at rest was scored by an observer blinded to clinical data. Normal contrast opacification predicted functional recovery with a positive predictive value of 63%, a negative predictive value of 73%, and an accuracy of 66%. Residual contractility during low-dose DE had a positive predictive value of 82%, a negative predictive value of 72%, and a predictive accuracy of 76%. When the 2 tests were concordant (64%), they had a positive predictive value of 81%, a negative predictive value of 85%, and a predictive accuracy of 83%. Low-dose DE was superior to intravenous MCE in the prediction of functional recovery of akinetic myocardium after AMI, but the combination of both maximizes predictive accuracy.     

Low-level exercise echocardiography detects contractile reserve and predicts reversible dysfunction after acute myocardial infarction: comparison with low-dose dobutamine echocardiography.

OBJECTIVES: The aim of this study was to evaluate low-level exercise echocardiography (LLEE) in detecting contractile reserve and predicting functional improvement of akinetic myocardium early after acute myocardial infarction (AMI). BACKGROUND: Experimental and clinical studies have shown that low-dose dobutamine enhances contractile function of dyssynergic but viable myocardium in patients with recent AMI. We hypothesized that endogenous catecholamines produced during a LLEE test could serve as a myocardial stressor to elicit contractile reserve. METHODS: Fifty-two consecutive patients with first AMI and > or =2 akinetic segments in the infarct-related territory underwent 5 +/- 2 days after AMI low-dose dobutamine echocardiography (LDDE) (5, 10 and 15 microg/kg/min) and LLEE (25 W during 3 min on a supine bicycle, with continuous echocardiographic recording). Both tests were performed on the same day, in random order. Follow-up echocardiography was obtained one month later. Regional wall thickening was semi-quantitatively assessed using a 16-segment, 5-grade scale model. Contractile reserve was defined as improvement in wall thickening of > or =1 grade. RESULTS: Mean increase in heart rate during stress tests was 15 +/- 7 beats/min with LLEE and 13 +/- 6 beats/min with LDDE (p = NS). Contractile reserve was detected in 119 (55%) of 217 akinetic segments at LLEE and in 137 (63%) segments at LDDE. At follow-up study, functional improvement was identified in 139 (64%) segments. Sensitivity, specificity and positive and negative predictive values for predicting functional recovery were 81%, 92%, 95% and 73%, respectively, for LLEE, and 91%, 86%, 92% and 84%, respectively, for LDDE. Moreover, there was a good correlation between systolic wall thickening measured in the center of the dyssynergic area during stress tests and at follow-up study: r = 0.77, p < 0.001 with exercise testing and r = 0.73, p < 0.001 with dobutamine testing. CONCLUSIONS: Low-level exercise echocardiography provides a promising alternative to LDDE for identifying myocardial viability and predicting reversible dysfunction early after AMI.     

Comparison of real-time contrast echocardiography and low-dose dobutamine stress echocardiography in predicting the left ventricular functional recovery in patients after acute myocardial infarction under different therapeutic intervention

BACKGROUND: Early prediction of left ventricular (LV) functional recovery after acute myocardial infarction (AMI) remains challenging. This prospective study aims to compare real-time myocardial contrast echocardiography (MCE) with low-dose dobutamine stress echocardiography (LDDSE) in predicting the LV functional recovery in patients after AMI who underwent different therapeutic interventions. METHODS: Ninety-two patients with AMI were divided into 3 groups: primary coronary intervention group (n=34), thrombolysis group (n=30) and conservative therapy group (n=28). MCE was performed 2.3+/-0.7 days after chest pain onset. LDDSE was done within 2 days of MCE study. Follow-up echocardiography was performed 4 months later. RESULTS: Patients treated by primary coronary intervention or thrombolysis had significantly lower regional perfusion score (0.65+/-0.53 vs. 1.01+/-0.49, p=0.008; 0.78+/-0.55 vs. 1.01+/-0.49, p=0.03), better contractile reserve (regional dobutamine Deltawall motion score -1.12+/-0.39 vs. -0.80+/-0.43, p=0.01; -0.99+/-0.50 vs. -0.80+/-0.43, p=0.08) and LV function recovery (regional Deltawall motion score -1.67+/-0.53 vs. -1.02+/-0.46, p=0.003; -1.42+/-0.58 vs. -1.02+/-0.46, p=0.03) than those of conservative therapy group. MCE and LDDSE showed good concordance for predicting LV functional recovery (kappa=0.63, p<0.001). Perfusion score index had a good correlation with LV functional recovery (r=-0.75, p<0.001). CONCLUSIONS: This study demonstrates that perfusion score index obtained from real-time MCE is comparable to LDDSE in predicting the LV functional recovery even under different therapeutic interventions. Revascularization results in better preservation of myocardial microvascular integrity, regional contractile reserve and LV functional recovery.     

Prediction of functional recovery in patients with myocardial infarction after revascularization--comparison of low-dose dobutamine stress echocardiography with fluorine-18 fluorodeoxyglucose positron emission tomography

The present study investigated the agreement between low-dose dobutamine stress echocardiography (LDDSE) and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and compared each technique's ability to detect myocardial viability and predict functional recovery in 30 patients. All patients underwent revascularization, followed by echocardiography 5+/-3 months. Of the 390 segments analyzed by echocardiography before revascularization, 110 (28%) had abnormal wall motion. LDDSE showed viability in 66 sites of the 110 dyssynergic segments and 58 of these viable segments recovered their wall motion. With FDG-PET, 78 of the 110 dyssynergic segments were diagnosed as viable and 62 of these showed improvement of the wall motion. The sensitivities for LDDSE and FDG-PET to assess functional recovery were 84% and 90%, respectively; specificities were 80% and 64%, respectively. Positive predictive values for LDDSE and FDG-PET were 88% and 79%; negative predictive values were 75% and 78%, respectively. Both methods had good sensitivity for detecting improvement in regional function after revascularization, but LDDSE had a higher specificity for detecting viability and a better positive predictive value for left ventricular functional recovery.     

Usefulness of myocardial contrast echocardiography using low-power continuous imaging early after acute myocardial infarction to predict late functional left ventricular recovery

Microvascular perfusion is a prerequisite for ensuring viability early after acute myocardial infarction (AMI). For adequate assessment of myocardial perfusion, both myocardial blood volume and velocity need to be evaluated. Due to its high frame rate, low-power continuous myocardial contrast echocardiography (MCE) can rapidly assess these parameters of myocardial perfusion. We hypothesized that the technique can accurately differentiate necrotic from viable myocardium after reperfusion therapy in AMI. Accordingly, 50 patients underwent low-power continuous MCE using intravenous Optison (Amersham Health, Amersham, Middlesex, United Kingdom) 7 to 10 days after AMI. Myocardial perfusion (contrast opacification assessed over 15 cardiac cycles after the destruction of microbubbles with high energy pulses) and wall thickening were assessed at baseline. Regional and global left ventricular (LV) function was reassessed after 12 weeks. Out of the 297 dysfunctional segments, MCE detected no contrast enhancement during 15 cardiac cycles in 172 segments, of which 160 (93%) failed to show improvement. MCE demonstrated contrast opacification during 15 cardiac cycles in 77 segments, of which 65 (84%) showed recovery of function. The greater the extent and intensity of contrast opacification, the better the LV function at 3 months (p <0.001, r = -0.91). Almost all patients (94%) with <20% perfusion in dysfunctional myocardium (assessing various cut-offs) failed to demonstrate an improvement in LV function. MCE and peak creatine kinase proved to be independent predictors of functional recovery (p <0.001). In conclusion, low-power continuous MCE is an accurate and rapid bedside technique to identify microvascular perfusion after AMI. This technique may be utilized to reliably predict late recovery of function in dysfunctional myocardium after AMI.     

Comparison of baseline and low-dose dobutamine technetium-99m sestamibi scintigraphy with low-dose dobutamine echocardiography for predicting functional recovery after revascularization

Injection of sestamibi during low-dose dobutamine (LDD) infusion might improve tracer ability to detect viable myocardium. This study investigated the potential value of LDD technetium-99m sestamibi (sestamibi) single-photon emission computed tomography (SPECT) in predicting functional recovery after revascularization by comparing its results with those of sestamibi SPECT at rest and of LDD echocardiography. Before revascularization, 23 patients with chronic coronary artery disease and regional left ventricular dysfunction underwent sestamibi SPECT at rest and, on a separate day, LDD echocardiography and sestamibi SPECT with tracer injection during LDD infusion. Echocardiography at rest was repeated after revascularization. Semiquantitative sestamibi uptake results (grading from 0 = normal to 4 = absent) and wall motion (grading from 1 = normal to 4 = dyskinesia) were evaluated with a 16-segment model. The ventricular wall was divided into 3 vascular territories. At follow-up, 20 of 32 asynergic vascular territories showed functional recovery, whereas 12 showed no changes. For prediction of functional recovery, LDD SPECT achieved better accuracy than SPECT at rest (87% vs 65%, p <0.05); positive and negative predictive values of LDD SPECT were 90% and 83%, respectively, which was not significantly different from the related LDD echocardiographic values (84% and 69%). Thus, LDD sestamibi SPECT appears to be a promising method for detecting myocardial viability, which provides better accuracy than sestamibi SPECT at rest, and achieves predictive values comparable to those of LDD echocardiography.     

Comparison of low-dose dobutamine stress echocardiography and echocardiography during glucose-insulin-potassium infusion for detection of myocardial viability after anterior myocardial infarction

BACKGROUND: Low-dose dobutamine stress echocardiography (LDDSE) is one of the methods most used to assess myocardial viability. Glucose-insulin-potassium (GIK) infusion has been shown to increase contraction of the ischemic zone. The aim of this study was to compare LDDSE and echocardiography during GIK infusion for detection of myocardial viability. METHODS: Thirty-two patients who had first anterior myocardial infarction (MI) without previous MI were included in the study. Echocardiographic evaluation was carried out on the 7th +/- 2 days after MI. During continuous electrocardiographic, blood pressure and echocardiographic monitoring, an intravenous infusion of dobutamine (3 microg/kg body weight/min) was started with an infusion pump, continued for 5 min and then increased to 5 microg/kg/min and 10 microg/kg/min for another 5 min. The GIK protocol consisted of a fixed dose of insulin (100 microU/kg/h intravenously) and a variable glucose/potassium infusion rate. GIK echocardiography was done at baseline and after 60 min of GIK. The detected viable myocardium was defined as one or two scores decreasing in at least two adjacent abnormal segments during LDDSE and GIK echocardiography. RESULTS: Under resting conditions 225 segments (44%) were normokinetic, 21 segments (4%) dyskinetic, 117 segments (23%) akinetic and 149 segments (29%) hypokinetic. Viability was detected in 20% (57 segments) of the asynergic segments at baseline with GIK echocardiography and in 22% (62 segments) of those segments with LDDSE (P < 0.05). Left ventricular wall motion score index at baseline was 1.87 and it decreased significantly indicating improvement in left ventricular systolic function during both LDDSE and GIK echocardiography (P < 0.001, versus 1.75 and 1.76 respectively). The agreement between LDDSE and GIK echocardiography for detection of myocardial viability was 96%. CONCLUSION: We have shown that GIK echocardiography is similar to LDDSE for detection of myocardial viability. With the support of further clinical studies GIK echocardiography could be used to detect myocardial viability after acute MI.     

Prognostic power of dobutamine echocardiography after uncomplicated acute myocardial infarction in the elderly

STUDY OBJECTIVES: To assess the prognostic value of dobutamine-atropine stress echocardiography (DSE) after uncomplicated acute myocardial infarction (AMI) in elderly patients. DESIGN: We analyzed 59 consecutive patients (42 men) aged > or = 70 years (mean +/- SD age, 75 +/- 4 years) who underwent DSE within 10 days after uncomplicated AMI. DSE was carried out following the standard protocol. Five myocardial responses were considered: (1) negative, (2) sustained improvement of contractility, (3) biphasic response (initial improvement followed by worsening), (4) worsening of contractility in the infarcted area, and (5) worsening at a distance. RESULTS: Mean follow-up duration was 13 +/- 8 months. Twenty-one patients had an event: cardiac death (n = 5), myocardial infarction (n = 1), heart failure (n = 1), unstable angina (n = 10), and revascularization (n = 4). Clinical and stress echocardiographic variables previously related to adverse prognosis were entered in Cox regression analysis, and the predictors of impaired outcome were inducible ischemia during DSE (hazard ratio [HR], 2.97; 95% confidence interval [CI], 1.77 to 4.99; p < 0.001) and resting wall motion score index (WMSI) > 1.6 (HR, 1.68; 95% CI, 1.02 to 2.77; p = 0.04). After excluding revascularization procedures and considering only spontaneous events, the following predictors were found: ischemia during DSE (HR, 2.95; 95% CI, 2.78 to 3.12; p < 0.001) and resting WMSI > 1.6 (HR, 2.53; 95% CI, 1.30 to 4.93; p = 0.006). CONCLUSIONS: Inducible ischemia during DSE within 10 days after uncomplicated AMI predicts an impaired outcome in the elderly.     

Early dobutamine echocardiography for the assessment of coronary stenosis after first Q-wave myocardial infarction

We assessed the accuracy of early dobutamine stress echocardiography to detect infarct-related coronary artery and multivessel disease in patients with first Q wave myocardial infarction after withdrawal of cardioactive drugs. Dobutamine-atropine echocardiography was performed in 91 consecutive patients (mean age 59+/-6 years) 7+/-4 days after myocardial infarction. Dobutamine was infused at incremental doses of 5, 10, 20, 30 to 40 microg/kg/min each one dose for 3 min. Peak heart rate was 134+/-17 bpm. All patients underwent coronary angiography before discharge. Sensitivity, specificity and accuracy of ischemic and biphasic response to detect residual stenosis of infarct-related coronary artery were 70, 92 and 73%, respectively. The sensitivity, specificity and accuracy of ischemic or biphasic response were similar in the vascular territories of left anterior descending (74, 86 and 75%, respectively), right (67, 100 and 70%, respectively) and circumflex coronary arteries (64, 100, and 69%, respectively). Sensitivity, specificity and accuracy of heterozonal wall motion abnormalities for multivessel coronary artery disease were 64, 82 and 76%, respectively. Dobutamine stress echocardiography is sensitive and specific in detecting residual coronary stenosis and multivessel disease in patients with first Q-wave myocardial infarction. The test is safe even without pharmacological protection.     

ST segment elevation during dobutamine stress echocardiography after acute myocardial infarction: Clinical significance and correlation with contractile recovery

ObjectivesThe aim of this study was the evaluation of the value of dobutamine stress induced ST-segment elevation after acute myocardial infarction in predicting spontaneous contractile recovery.MethodsFifty eight consecutive patients were studied within 7 days after first acute myocardial infarction (AMI) with dobutamine stress echocardiography (DSE). A score model based on 16 segments and four grades was used to assess the left ventricular function and a twelve-lead electrocardiography was continuously monitored throughout the test. Follow up was performed by trans-thoracic echocardiography at 90 days. At follow up, contractile recovery was defined as improvement of wall motion score by more than one grade in at least two myocardial segments.ResultsST-segment elevation was observed in 24 (41%) out of the 58 patients studied. During DSE; persistent segmental wall motion abnormalities were more frequently observed in patients without ST-segment elevation while improvement without subsequent worsening was more frequently observed in patients with ST-segment elevation (P = 0.001). On follow up, contractile recovery was reported in 37 (64%) patients, it was more frequently observed in patients who already developed ST-segment elevation during DSE (P = 0.007). Dobutamine induced ST-Segment elevation has the sensitivity, specificity, positive and negative predictive values of 66%, 86%, 88% and 53%, respectively to predict spontaneous contractile recovery after AMI, while the combined sensitivity, specificity, positive and negative predictive values of dobutamine echocardiography and electrocardiography were 73%, 89%, 94% and 64%, respectively.ConclusionsDobutamine stress induced ST segment elevation occurring in electrocardiographic leads exploring an infarct area is a predictor of spontaneous contractile recovery after AMI particularly when combined with echocardiogarphic evidence of myocardial viability.     

Usefulness of myocardial contrast echocardiography in predicting global left ventricular functional recovery after anterior wall acute myocardial infarction

Although multiple recent studies have shown that myocardial contrast echocardiography (MCE) reliably differentiates between regional stunning and necrosis after acute myocardial infarction (AMI), prognosis is more closely related to measures of global left ventricular systolic function. One hundred fifteen patients underwent baseline wall motion assessment and MCE 2 days after admission and follow-up echocardiography a mean of 69 days later. Good agreement was found between perfusion score index and follow-up wall motion score index, indicating that MCE performed early after anterior wall AMI may be clinically useful in routine post-AMI risk stratification.     

低剂量多巴酚丁胺超声心动图试验在检出急性心肌梗死后存活心肌中的应用

目的　探讨低剂量多巴酚丁胺超声心动图试验 ( L DDE)评价急性心肌梗死 ( AMl)后存活心肌的价值及安全性。方法　 AMI患者 2 4例 ,男 2 3例 ,女 1例 ,平均年龄 5 3.1岁 ,在 AMI发病 1个月内 ,进行冠状动脉造影及血管重建术 ( PTCA、支架置入术或CABG)。L DDE在 AMI后 10～ 14 d(平均 10± 3d)进行 ,应用超声心动图 16节段半定量分析法对左心室各节段收缩运动和增厚情况给予分级记分 ,依据试验前后异常节段收缩功能改善情况 ,计算 L DDE评价急性心肌梗死后存活心肌的准确性。结果　 L DDE评价存活心肌的敏感性和特异性分别为 73.3%和 89.3% ,阳性预测值、阴性预测值及准确性分别为 78.8%、86.2 %和 83.7% ,无明显副作用。结论　L DDE能够显著提高存活心肌的检出率 ,对 AMI后血管重建术的疗效判定及临床适应证的选择具有较高的应用价值