Dobutamine-atropine stress echocardiography for reversible dysfunction during the first week after acute myocardial infarction: limitations and determinants of accuracy

Recent advances in dobutamine stress echocardiography

Dobutamine stress echocardiography (DSE) is a reliable cardiac risk stratifier that has widespread applicability because of its clinical accuracy and cost effectiveness. Dobutamine has positive inotropic and chronotropic effects and is commonly used in patients who cannot exercise or achieve an adequate heart rate response with exercise. Recently available long-term results from several independent clinical trials, combined with enhancements in image quality, have improved the ability to detect significant coronary artery disease and determine myocardial viability. Dobutamine stress echocardiography has an excellent safety profile with clinical results superior to regular exercise electrocardiography and comparable with exercise echocardiography and radionucleotide perfusion stress imaging. Low-dose dobutamine response can accurately predict dysfunctional yet viable myocardial regions that may improve with revascularization. Clinical studies are now available refining the common use of DSE preoperatively in female patients with valvular disease, as well as in the emergency department. Dobutamine stress echocardiography does have some limitations in discriminating particular regions of ischemia when multiple ventricular segments are involved and when the imaging is suboptimal. It can be applied using minimal additional resources in an otherwise functioning echocardiography laboratory and, with appropriate training, can result in clinical results comparable with those of large-scale multicenter trials. Ongoing improvements in technology and the development of new reagents such as myocardial contrast agents hold promise for further advancement in the near future.

Acute Myocardial Infarction Early Viability Assessment by 64-Slice Computed Tomography Immediately After Coronary Angiography

OBJECTIVES

Early evaluation of myocardial viability in acute myocardial infarction is useful to guide therapy. Therefore, we assessed 64-slice computed tomography (CT) immediately after coronary angiography in this setting.

BACKGROUND

Recent preliminary studies have shown the promising usefulness of late hyperenhancement multislice computed tomography (MSCT) for non-viability assessment.

METHODS

Thirty-six patients admitted for a first acute myocardial infarction had a coronary angiogram early after admission followed by 64-slice CT without iodine reinjection. The 16 segments of the left ventricle depicted by the American Society of Echocardiography were graded: no, subendocardial, or transmural hyperenhancement. No or subendocardial hyperenhancement were expected to reflect viability. Two to 4 weeks later, the same segments' contractility was evaluated at rest. Low-dose dobutamine echocardiography was performed in case of akinetic segment at rest.

RESULTS

Mean delay between coronary angiography and MSCT was 24 +/- 11 min (range 7 to 51 min). We compared 576 segments evaluated by each method. Agreement was noted for 560 segments (97%) and disagreement for 16 segments (3%). Thus, 64-slice CT after coronary angiography for an acute myocardial infarction had 98% sensitivity, 94% specificity, 97% accuracy, and 99% positive and 79% negative predictive values for detecting viable myocardial segments at a very early stage of an acute myocardial infarction. On a per-patient analysis, sensitivity, specificity, accuracy, and positive and negative predictive values were 92%, 100%, 94%, and 100% and 85%, respectively.

CONCLUSIONS

A 64-slice CT after coronary angiography for an acute myocardial infarction is a promising method for early evaluation of viable myocardium.

Nuclear Cardiology: Present and Future

Nuclear cardiology has made significant advances since the first reports of planar scintigraphy for the evaluation of left ventricular perfusion and function. While the current "state of the art" of gated myocardial perfusion single-photon emission computed tomographic (SPECT) imaging offers invaluable diagnostic and prognostic information for the evaluation of patients with suspected or known coronary artery disease (CAD), advances in the cellular and molecular biology of the cardiovascular system have helped to usher in a new modality in nuclear cardiology, namely, molecular imaging. In this review, we will discuss the current state of the art in nuclear cardiology, which includes SPECT and positron emission tomographic evaluation of myocardial perfusion, evaluation of left ventricular function by gated myocardial perfusion SPECT and gated blood pool SPECT, and the evaluation of myocardial viability with PET and SPECT methods. In addition, we will discuss the future of nuclear cardiology and the role that molecular imaging will play in the early detection of CAD at the level of the vulnerable plaque, the evaluation of cardiac remodeling, and monitoring of important new therapies including gene therapy and stem cell therapy.

Early negative T waves and viable myocardium in patients with a first ST-elevation acute coronary syndrome

Deep negative T waves (NTW) are a frequent finding following acute ST-segment elevation coronary syndromes but its possible relation with the status of regional contractility remains unclear. We studied 52 patients with a first ST-elevation acute coronary syndrome with or without NTW in anterior leads (> or =3 mm in > or=3 leads) and assessed the ejection fraction and regional myocardial contractility by contrast left ventriculography at baseline and during a low-dose dobutamine test (10 microg/kg per minute). Ejection fraction and regional contractility tended to be more preserved in patients with NTW, but dobutamine increased regional contractility in the jeopardized area in most patients with or without NTW and the improvement was similar in those either with or without enzyme elevation. In conclusion, deep NTW after ST-elevation acute coronary syndromes tends to be associated with a more preserved myocardium but it is neither a sensitive nor a specific marker of viable myocardium.

[Predictive significance of residual ischemia detected by the dobutamine stress-echocardiography test soon after the first uncomplicated myocardial infarction]

BACKGROUND

To evaluate the long-term prognostic value of dobutamine stress-echocardiography (ECG) test for new coronary events (new episodes of angina pectoris, cardiac-related deaths, and reinfarctions) early after the first uncomplicated myocardial infarction.

METHODS

Dobutamine stress-echocardiography tests were performed in all of 104 patients 10-20 days after the first myocardial infarction. Patients were followed-up for 36 (29 +/- 7) months. Kaplan-Meier cumulative survival curves were tested by Breslow test (Log Rank).

RESULTS

Two cardiac deaths (1.92%), nine nonfatal myocardial infarctions (8.65%), and three cases of recurrent angina pectoris (2.88%) occurred during the prospective follow-up. Cumulative survival curves showed that in patients with negative findings of dobutamine stress-echocardiography test, survival time without significant events was 35.31 months, while in the group with positive findings of dobutamine stress-echocardiography test it was 30.91 months (log Rank 7.22; p<0.01). Prognostic value of dobutamine stress-echocardiography test was analyzed by Cox regression model and was 2.92, meaning that the risk of significant events was 2.92 times higher in the group of patients with positive findings of dobutamine stress-echocardiography test.

CONCLUSION

Patients with negative findings of dobutamine stress-echocardiography test were with significantly higher possibility of surviving without significant events in comparison with the patients in whom the findings of dobutamine stress-echocardiography test were positive. In combination with clinical signs and ECG results, the results of dobutamine stress-echocardiography test improved prognostic value in the patients with the first uncomplicated myocardial infarction, and in that way influenced the strategy of their further treatment.

Delayed contrast-enhanced magnetic resonance imaging for the prediction of regional functional improvement after acute myocardial infarction

OBJECTIVES

We evaluated whether delayed contrast-enhanced magnetic resonance imaging (DCE-MRI) using an extracellular contrast agent could predict improvement of dysfunctional but viable myocardium after acute reperfused myocardial infarction (MI).

BACKGROUND

The transmural extent of hyperenhancement at DCE-MRI has been related to improvement of function in reperfused MI. However, evidence is still limited, and earlier reports have produced conflicting results regarding the significance of contrast patterns after infarction.

METHODS

Thirty patients (mean age 59 +/- 11 years, 27 males) underwent cine MRI and DCE-MRI 7 +/- 3 days after a first reperfused acute MI and follow-up cine MRI at 13 +/- 3 weeks. Segmental wall thickening and segmental extent of hyperenhancement were scored in 1,689 segments.

RESULTS

Of 500 dysfunctional segments, 273 (55%) improved at follow-up. There was no difference in likelihood of improvement or complete functional recovery between segments with 0% and 1% to 25% hyperenhancement. The likelihood of improvement of segments without hyperenhancement was 2.9, 14.3, and 20 times higher than that of segments with 26% to 50%, 51% to 75%, and >75% hyperenhancement, respectively (p < 0.001). The likelihood of complete functional recovery of segments without hyperenhancement was 3.8, 11.1, and 50 times higher than that of segments with 26% to 50%, 51% to 75%, and >75% hyperenhancement, respectively (p < 0.001).

CONCLUSIONS

In patients with recent reperfused MI, functional improvement of stunned myocardium is predicted by DCE-MRI.

Enoximone very low-dose dobutamine stress echocardiography: a new test for detecting viability in severe myocardial dysfunction after acute myocardial infarction

Relying on the synergistic action on contractility of enoximone and dobutamine when concomitantly infused, 25 patients with their first acute Q-wave anterior myocardial infarctions underwent conventional low-dose dobutamine echocardiography (LDE) and enoximone very-LDE to assess myocardial viability in severely dysfunctioning areas. Images were recorded at peak of pharmacodynamic effect of drugs and 4 months after revascularization. At peak-dose stage of LDE and enoximone very-LDE the regional infarct zone wall-motion score significantly decreased from the basal value of 25.6 +/- 2.9 to 16 +/- 6.0 (P <.001) and to 14.5 +/- 5.2 (P <.001), respectively. A high correlation was found by comparing the wall-motion score of each patient calculated at peak effect of combined drug administration with follow-up values (r(s) = 0.9). Enoximone very-LDE has proven to be a new test useful to evaluate viability in asynergic segments especially when the results of conventional tests are questionable.

Incremental value of myocardial contrast echocardiography for the prediction of recovery of function in dobutamine nonresponsive myocardium early after acute myocardial infarction

We hypothesized that the presence of microvascular integrity, detected by myocardial contrast echocardiography (MCE) in dobutamine nonresponsive segments, may enhance identification of recovery of function, which is a surrogate marker of myocardial viability. Accordingly, 96 patients underwent dobutamine echocardiography (DE) and intravenous MCE on the same day, 4.6 +/- 1.5 days after acute myocardial infarction (AMI). Recovery of function of akinetic segments was assessed at 3 months after AMI. Of 387 akinetic segments, 102 (26%) recovered function during follow-up. Sensitivities and specificities of MCE, DE, and the combination of DE and MCE in dobutamine nonresponsive segments were 58%, 59%, and 79%, respectively (p <0.001, compared with MCE and DE) and 76%, 84%, and 69%, respectively (p <0.05 compared with DE) for predicting recovery of function. In anterior AMI, the positive and negative predictive values of MCE, DE, and the combination of DE and MCE were 47% and 88%, 57% and 89%, and 49% and 95%, respectively. Multivariate analysis using clinical characteristics, electrocardiography, biochemical factors, MCE, and DE showed that the combination of DE and MCE in dobutamine nonresponsive segments (p <0.00001) and Q-wave AMI (p = 0.002) were the only independent predictors of recovery of function. Thus, for optimum prediction of recovery of function after AMI, a combination of DE and MCE in dobutamine nonresponsive segments may be utilized.

Contribution of the sST elevation/T-wave normalization in Q-wave leads during routine, pre-discharge treadmill exercise test to patient management and risk stratification after acute myocardial infarction: a 2.5-year follow-up study

OBJECTIVES

This study investigated whether ST-segment elevation and T-wave normalization (TWN) in Q-wave leads on pre-discharge exercise electrocardiogram (ECG) can contribute to patient management after a recent myocardial infarction (MI).

BACKGROUND

The clinical relevance of these exercise ECG changes remains controversial despite accumulating evidence of their association with myocardial viability. Because discrepancies of previous studies may depend on patient selection, the value of these ST/T abnormalities in the thrombolytic era should be better defined.

METHODS

One-hundred one patients, age 58 +/- 11 years, with a recent, first Q-wave MI (57% thrombolyzed, ejection fraction 43 +/- 7%) underwent pre-discharge, submaximal treadmill testing followed, in the absence of severe ischemia, by dobutamine stress echocardiography, thallium-201 single photon emission computed tomography, and coronary angiography.

RESULTS

ST elevation at peak exercise, but not TWN, was associated with more severe infarctions as indicated by higher peak creatine kinase (p < 0.05) and with a greater number of scarred segments both on echocardiography (p < 0.05) and scintigraphy (p < 0.01). However, the incidence of myocardial viability and ischemia did not differ between groups with or without these ST/T changes. Anterior infarction location and >or=3 echocardiographically scarred segments were among the independent predictors of ST elevation at peak ergometric exercise. During follow-up (31 +/- 13 months), the rate of hard events was low (8%) and similar between the study groups.

CONCLUSIONS

In patients after acute Q-wave MI without severe ischemia according to clinical and standard ECG criteria, exercise-induced ST elevation, but not TWN, is associated with larger infarctions. The contribution of these ST/T abnormalities toward identifying patients with myocardial viability or ischemia and determining risk stratification is poor. In-hospital management of such patients based on routine clinical practice is sufficient for selection of a population with a relatively low long-term risk.

Age-related determinants of outcome after acute myocardial infarction: a dobutamine-atropine stress echocardiographic study

OBJECTIVES

To investigate the cause of worse survival in older patients after myocardial infarction (MI).

DESIGN

Prospective 18-month and longer follow-up study of a cohort of 167 patients (mean age +/- standard deviation 58 +/- 12, including 71 aged >or=65) with acute MI for cardiac events, defined as cardiac death, recurrent MI, or resuscitated ventricular tachycardia or fibrillation (VT/VF).

SETTING

Milwaukee County Medical Complex and the Zablocki Veterans Affairs Medical Center, Milwaukee, WI.

PARTICIPANTS

One hundred sixty-seven patients who underwent dobutamine-atropine stress echocardiography (DASE) in the first week (2-7 days) after acute MI and were medically managed.

MEASUREMENTS

Comparison of event rates in older (>or=65 years) and younger (<65 years) patients and of clinical, resting echocardiographic, DASE, and angiographic findings in patients with and without events. Coronary angiography was performed in 141.

RESULTS

Older and younger patients tolerated DASE well. During follow-up, there were 29 cardiac events (cardiac death in 17, nonfatal MI in 10, and VT/VF in 2). Events were more common in older patients (26% vs 12%, P <.05), especially death (19% vs 5%, P <.05). Scar size in the infarct zone by DASE was larger (4.0 +/- 2.8 vs 3.0 +/- 2.7 segments, P <.05) and remote wall motion abnormalities more common (47 vs 29%, P <.05) in older patients. Univariate determinants of outcome (P <.05) in older patients were diabetes mellitus; remote wall motion abnormalities; angiographic multivessel disease; scar size; ejection fraction; and resting, low-, and peak-dose wall motion score. Univariate determinants in younger patients were similar, but diabetes mellitus was not. Multivariate analysis revealed that remote wall motion abnormalities and scar size by DASE were independently predictive of outcome in older and younger patients and diabetes mellitus only in older patients. Low- and peak-dose DASE data enhanced (P <.01) the prediction of outcome in all patients with acute MI relative to clinical data and resting echocardiography.

CONCLUSION

DASE was more predictive of outcome than clinical data and resting echocardiography in both age groups. Scar size and remote wall motion abnormalities were the primary determinants of outcome irrespective of age. The worse prognosis of older patients correlated with diabetes mellitus, greater scar size, and higher incidence of remote inducible ischemia.

Magnetic resonance tagging and echocardiographic response to dobutamine and functional improvement after reperfused myocardial infarction

OBJECTIVE

Our objective was to compare the qualitative response to low-dose dobutamine by echocardiography (DSE) with the quantitative response of magnetic resonance myocardial tagging (DMRT) in the prediction and evaluation of functional improvement after reperfused myocardial infarction (MI).

METHODS

Twenty-two patients with a reperfused first MI (aged 51 +/- 2 years, 20 male, 13 anterior MI) were studied. On day 3 +/- 1 after MI, patients underwent both DSE and DMRT at baseline and during infusion of 5 microg/kg/min and 10 microg/kg/min of dobutamine. The patients returned at week 8 +/- 1 for follow-up echocardiogram and MRT at rest. Two experienced observers interpreted the DSE for the presence of contractile reserve and functional improvement in dysfunctional segments. By DMRT, a 5% increase in percent intramyocardial circumferential shortening at peak response to dobutamine was defined as evidence of contractile reserve. Functional improvement by echocardiography was defined as the gold standard.

RESULTS

Ejection fraction improved from 46% +/- 10% at week 1 to 51% +/- 12% at week 8 (P <.001) in the patients. Sixty-seven transmural segments with baseline dysfunction matched between imaging modalities by location were studied. For 51 (76%) of the segments, echocardiography and MR tagging were concordant in the assessment of functional improvement (kappa value 0.52). Twenty-nine segments (43%) demonstrated improvement by echocardiography, whereas 33 segments (49%) improved by MR tagging. With improvement of function by echocardiography as gold standard, the sensitivity and specificity of DMRT for prediction of functional improvement was 86% and 69%, respectively, with an overall accuracy of 76%. The sensitivity, specificity, and accuracy of DSE was 86%, 87%, and 85%, respectively. Overall accuracy was similar between techniques.

CONCLUSIONS

Both DSMRT and DSE are sensitive and accurate techniques for predicting functional improvement after reperfused MI.

Prognostic implications of evaluation of contractile reserve in akinetic and hypokinetic segments during low dose dobutamine echocardiography in patients with acute myocardial infarction

BACKGROUND

Previous studies have reported the prognostic value of myocardial viability (MV) detected using low-dose dobutamine echocardiography (DbE). However, viability was frequently evaluated as improvement in regional wall motion score index, which includes increased function in hypokinetic segments, in which viable myocardium is necessarily present. It is not known whether an evaluation focusing on akinetic segments, in which the possible presence of viable myocardium is unknown, might have more prognostic value. The aim of this study was to compare the prognostic value of the improvement of myocardial function during dobutamine infusion in akinetic and hypokinetic regions in patients with acute myocardial infarction (AMI).

METHODS

191 patients with uncomplicated AMI and at least one akinetic segment were retrospectively selected from those consecutively examined at our echo-laboratory to evaluate MV using DbE. Myocardial viability was evaluated both as an increment in RWMSI (Delta RWMSI), which takes into consideration improvement in both akinetic and hypokinetic regions, and as an improvement of function in akinetic (Delta akinetic) and hypokinetic (Delta hypokinetic), segments considered separately. Follow-up evaluation was performed at 30+/-13 months.

RESULTS

On the basis of the Delta RWMSI, 94/191 patients were judged to have myocardial viability, whereas considering myocardial viability in akinetic segments only, 72/191 patients showed viability. At follow-up 18 patients had died (six viable considering Delta RWMSI; three viable considering Delta akinetic). The presence of a previous AMI, the site of AMI, RWMSI and the number of akinetic segments, and Delta RWMSI and Delta akinetic were related to mortality at univariate Cox analysis. At multivariate stepwise Cox regression analysis Delta akinetic, but not Delta hypokinetic proved to be significantly related to mortality. The Kaplan-Meier survival curves were no different in patients with or without viable myocardium evaluated as Delta RWMSI, while they were significantly different considering patients with or without viability in akinetic segments (P=0.04).

CONCLUSION

In conclusion our study confirms the prognostic importance of the evaluation of myocardial viability in infarcted patients. However, it points out that it is the presence of viability in akinetic segments that affects long-term survival in these patients. This supports the hypothesis that other mechanisms, above and beyond the effect on regional wall motion, are involved in the beneficial effects of myocardial viability.

Echocardiographic assessment of viable myocardium

Left ventricular function is one of the most important determinates of long-term prognosis in patients with coronary artery disease. In recent years, it has become apparent that left ventricular dysfunction in patients with coronary artery disease is not always an irreversible process stemming from myocardial necrosis and fibrosis. Myocardial tissue can undergo both a state of potential reversible dysfunction because of prolonged sustained ischemia (hibernating myocardium) or episodes of acute ischemia (stunned myocardium). Revascularization of this tissue may improve regional and global left ventricular function and therefore prognosis. Numerous studies have now firmly established dobutamine echocardiography as a safe, reliable, and accurate imaging modality in the assessment of reversible left ventricular dysfunction. Furthermore, dobutamine echocardiography has been shown to have good sensitivity, specificity, and, more importantly, positive predictive accuracy in identifying both acute and chronic reversible left ventricular dysfunction for risk satisfaction and prognosis.

Contractile reserve and contrast uptake pattern by magnetic resonance imaging and functional recovery after reperfused myocardial infarction

OBJECTIVES

We hypothesized that contrast-enhanced and dobutamine tagged magnetic resonance imaging (MRI) could investigate microvascular integrity and contractile reserve of reperfused myocardial infarction (MI) in one examination.

BACKGROUND

In reperfused MI, microvascular integrity and contractile reserve are important determinants of functional recovery.

METHODS

Twenty-three patients with a reperfused first MI were studied. On day 3+/-1 after MI, patients underwent tagged MRI at baseline and during infusion of 5 and 10 microg/kg/min of dobutamine followed by contrast-enhanced MRI (first pass and delayed imaging) after a bolus infusion of gadolinium-diethylenetriaminepenta-acetic acid. Tagged MRI was performed 9+/-1 weeks later (follow-up). Eighty-four transmural regions with hyperenhancement on delayed contrast-enhanced images were defined as COMB (first pass hypoenhancement) or HYPER (normal first pass signal enhancement). Percent circumferential segment shortening was measured within the subendocardium and subepicardum of each region of HYPER or COMB at baseline, peak dobutamine and follow-up.

RESULTS

Shortening improved in COMB regions from 4+/-1% at baseline to 10+/-1% at peak dobutamine and 10+/-1% at follow-up, respectively (p<0.0003 vs. baseline for both). The HYPER regions likewise improved from 10+/-1% at baseline to 16+/-1% and 17+/-1%, respectively (p<0.0004 vs. baseline for both). Function within COMB regions was less than that of HYPER at baseline, peak dobutamine and follow-up (p<0.0003 for all).

CONCLUSIONS

Dobutamine magnetic resonance tagging and contrast enhanced MRI are complementary in assessing functional recovery after reperfused MI. Regions of delayed contrast hyperenhancement demonstrate both contractile reserve and late functional recovery. However, if these regions demonstrate first pass contrast hypoenhancement, they are associated with greater myocardial damage.

Reversible left ventricular dysfunction

The extent and degree of myocardial viability are important parameters in the risk stratification of patients with significant left ventricular dysfunction secondary to coronary artery disease. Although several imaging modalities can identify viable myocardium, dobutamine stress echocardiography has gained considerable importance as an accurate, safe, and reliable method. In patients with significant left ventricular dysfunction secondary to coronary artery disease, identification of the presence and extent of contractile reserve and, therefore, viable myocardium during low-dose dobutamine infusion can predict the recovery of left ventricular function after revascularization, survival rate, and future cardiac events.

[Determinants of contractile reserve in the infarction area. A quantitative study using dobutamine in contrast left ventriculography]

AIM

The aim of this study was to relate the contractile reserve in infarction segments to the dysfunction at rest and to the residual coronary stenosis.

METHODS

The study group consisted of 95 patients with a first myocardial infarction. Contrast left ventricular at baseline and after dobutamine infusion at 7.5 microg/kg/min and coronary angiograms were performed. The centerline method was used to quantify the extent of dysfunction (percentage of chords with dysfunction in the territory of the infarction artery) and its maximum severity (maximum units of standard deviation [SD] below the normal wall motion reference). Reduction of dysfunction extent with dobutamine was measured.

RESULTS

On increasing baseline dysfunction severity, both the magnitude of the response to dobutamine ( 2 SD 3 SD 4 SD +/- 5 SD [n = 15] = 9+/-13%, > 5 SD [n = 13] = 3+/-4%, p = 0,0001), and the number of patients with a significant (> or =15%) positive response ( 2 SD 3 SD 4 SD 5 SD = 0%, p<0,0001) decreased. There were no differences in dobutamine improvement among the subgroups with (n = 84) or without (n = 11) significant stenosis in the infarction artery (18+/-15 vs. 16 +/-18%), or between the subgroups with a patent (n = 76, 18+/-19%) or occluded (n = 19, 11+/-11%) artery.

CONCLUSIONS

Dobutamine response is related to dysfunction severity in the infarction area: when the severity is 5 (high negative response prevalence), dobutamine testing does not seem indicate. The existence of residual coronary stenosis does not attenuate contractile reserve at low dobutamine doses.

Significance of T-wave changes during early dobutamine stress echocardiography in patients with Q-wave acute myocardial infarction

The relation between T-wave changes and regional contraction during dobutamine stress echocardiography at low (5 to 10 microg/kg/min) and high (20 to 40 microg/kg/min) doses in 43 consecutive patients, early (7+/-2 days) after first recent Q-wave acute myocardial infarction has been evaluated. T-wave changes detected in > or =2 infarct-related electrocardiographic leads during dobutamine infusion were defined as follow: (1) negative T waves becoming positive, (2) positive T waves becoming upright > or =2 mm, and (3) negative T waves becoming upright > or =2 mm from baseline. Wall motion score index (WMSI) was defined as the sum of the echocardiographic scores of 16 segments divided by total segments considered at baseline, and at low and peak doses of dobutamine. Patients were classified according to the absence or presence of dobutamine T-wave changes. Those without T-wave changes had a significantly higher WMSI at rest (1.68+/-0.23 vs 1.50+/-0.21; p <0.05) and at peak (1.77+/-0.34 vs 1.51+/-.30 p <0.05) of dobutamine stress testing, without higher incidence of viability, homozonal, and heterozonal ischemia and chest pain. The angiographic patterns were similar between groups. Regression analysis showed a significant correlation between WMSI and T-wave amplitude at baseline (R = 0.38, p = 0.01) and at peak dobutamine stress testing (R = 0.50, p = 0.0006). The sensitivity sensitivity, specificity, and accuracy of T-wave changes to detect myocardial viability were 0.27, 0.84, and 0.70, respectively. The sensitivity, specificity, and accuracy of T-wave changes to detect homozonal ischemia were 0.76, 0.27, and 0.46, respectively. In conclusion, dobutamine-induced T-wave changes are associated with a greater extent of wall motion abnormalities both at rest and at peak stress echocardiography, but they are of little value in predicting myocardial viability when analyzed early after myocardial infarction.

Dobutamine-atropine stress echocardiography for risk stratification in patients with chronic left ventricular dysfunction

OBJECTIVE

To assess the prognostic value of sustained improvement, scar and inducible ischemia with or without viability in patients with chronic left ventricular dysfunction (LVD).

BACKGROUND

Dobutamine-atropine stress echocardiography (DASE) accurately detects scar, reversible dysfunction and the extent of coronary artery disease in LVD.

METHODS

Three hundred fifty consecutive patients (age 62+/-13 years, mean+/-SD, 215 men/135 women) with moderate to severe LVD (LVEF < 40%, mean 30+/-8%) underwent DASE and were followed for > or =18 months. Dobutamine-atropine stress echocardiographic findings were classified according to sustained improvement in all vascular territories, scar, inducible ischemia (worsening wall motion at peak dose only or biphasic responses) and their extent.

RESULTS

Sustained improvement occurred in 83 patients (24%), scar alone in 99 (28%) and inducible ischemia in 168 (48%, with biphasic responses in 104). Ischemia was induced in all vascular territories in 26 patients. Patients with sustained improvement or scar alone were treated medically, whereas 46% (78/168) with inducible ischemia were revascularized (coronary bypass surgery, n = 67 or angioplasty, n = 11). There were 76 hard events including cardiac death in 59, nonfatal myocardial infarction in 11, and resuscitated sudden death in 6. Hard events were rare in sustained improvement (5%, 4/83), uncommon in scar (13%, 13/99) and common (p < 0.01) in medically treated patients with inducible ischemia (59%, 53/90). Cardiac deaths were especially common (p < 0.01) in patients with biphasic responses (55%, 28/51). Inducible ischemia independently predicted hard events (chi2 = 75.35, p < 0.001) along with reduced LVEF at peak dose (chi2 = 8.38, p = 0.004). Hard cardiac events were uncommon (8%, 6/78, p < 0.001) in patients with inducible ischemia who underwent early revascularization.

CONCLUSIONS

Inducible ischemia during DASE was the major determinant of outcome in LVD and independent of clinical data and left ventricular function. Improved wall thickening alone and scar alone predicted good outcome. Survival of patients with inducible ischemia was better after revascularization.