Safety and accuracy of dobutamine-atropine stress echocardiography for the detection of residual stenosis of the infarct-related artery and multivessel disease during the first week after acute myocardial infarction

Functionally Complete Coronary Revascularisation in Patients Presenting with ST-elevation MI and Multivessel Coronary Artery Disease

Up to half of patients undergoing primary percutaneous coronary intervention of a culprit stenosis in the context of the ST-elevation MI may present with multivessel disease. The presence of non-culprit stenoses have been shown to affect the outcomes of these patients, and the results of the more recent randomised trials highlight the importance of complete coronary revascularisation. In this paper, the authors review the main trials published on the topic and discuss tools for the assessment of non-culprit stenoses, while considering the right time for carrying out a complete coronary revascularisation.

Sinogram smoothing techniques for myocardial blood flow estimation from dose-reduced dynamic computed tomography

Dynamic contrast-enhanced computed tomography (CT) could provide an accurate and widely available technique for myocardial blood flow (MBF) estimation to aid in the diagnosis and treatment of coronary artery disease. However, one of its primary limitations is the radiation dose imparted to the patient. We are exploring techniques to reduce the patient dose by either reducing the tube current or by reducing the number of temporal frames in the dynamic CT sequence. Both of these dose reduction techniques result in noisy data. In order to extract the MBF information from the noisy acquisitions, we have explored several data-domain smoothing techniques. In this work, we investigate two specific smoothing techniques: the sinogram restoration technique in both the spatial and temporal domains and the use of the Karhunen-Loeve (KL) transform to provide temporal smoothing in the sinogram domain. The KL transform smoothing technique has been previously applied to dynamic image sequences in positron emission tomography. We apply a quantitative two-compartment blood flow model to estimate MBF from the time-attenuation curves and determine which smoothing method provides the most accurate MBF estimates in a series of simulations of different dose levels, dynamic contrast-enhanced cardiac CT acquisitions. As measured by root mean square percentage error (% RMSE) in MBF estimates, sinogram smoothing generally provides the best MBF estimates except for the cases of the lowest simulated dose levels (tube current = 25 mAs, 2 or 3 s temporal spacing), where the KL transform method provides the best MBF estimates. The KL transform technique provides improved MBF estimates compared to conventional processing only at very low doses (<7 mSv). Results suggest that the proposed smoothing techniques could provide high fidelity MBF information and allow for substantial radiation dose savings.

Cardiac imaging after myocardial infarction

After myocardial infarction, optimal clinical management depends critically on cardiac imaging. Remodelling and heart failure, presence of inducible ischaemia, presence of dysfunctional viable myocardium, future risk of adverse events including risk of ventricular arrhythmias, need for anticoagulation, and other questions should be addressed by cardiac imaging. Strengths and weaknesses, recent developments, choice, and timing of the different non-invasive techniques are reviewed for this frequent clinical scenario.

Rupture of papillary muscle during dobutamine stress echocardiography

A 72-year-old man presented with an acute myocardial infarction, he did not receive any reperfusion therapy because he presented as a non-ST elevation myocardial infarction (MI). A dobutamine stress echocardiography was done five days after. A partial rupture of the posterior papillary muscle occurred during the stress test. The patient developed cardiogenic shock; he improved after medical management, and mitral repair was done a few days after.

Current status of stress echocardiography

Stress echocardiography is a widely applied technique for the evaluation of individuals with known or suspected coronary artery disease. The technique combines echocardiographic imaging with exercise testing or pharmacologic stress. Advances in digital image acquisition and harmonic imaging have substantially improved the quality of echocardiographic images, and have therefore increased general applicability of stress echocardiography.

Prediction of postinfarction remodeling of the left ventricle from parameters of tissue Doppler echocardiography

The possibility of predicting undesirable postinfarction remodeling of the left ventricle from parameters of tissue doppler echocardiography was evaluated in 55 patients with a history of acute myocardial infarction. Low diastolic rates of normal segments and the absence of the peak of isovolumetric contraction in the dysfunction zone were the most significant predictors of unfavorable remodeling.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Ventricular Fibrillation in Late Recovery After Dobutamine Stress Echocardiography

A 62-year-old man with multiple cardiac risk factors, including diabetes mellitus type II, treated hypertension, and hyperlipidemia, had a dobutamine stress echocardiogram performed as part of a preoperative evaluation. At peak stress the patient developed an apical regional wall motion abnormality. Approximately 12 minutes into the recovery period, the patient developed ventricular tachycardia that degenerated into ventricular fibrillation. He was successfully resuscitated and underwent emergency coronary angiography that showed a 95% distal left anterior descending coronary artery stenosis.

The effects of beta-blockers on dobutamine-atropine stress echocardiography: early protocol versus standard protocol

Background

To study the effects of Beta-blockers during Dobutamine Stress Echocardiography (DSE) comparing the hemodynamic benefits of an early administration of atropine in patients taking or not Beta-blockers.

Methods

One hundred and twenty-one patients were submitted to dobutamine stress echocardiography for the investigation of myocardial ischemia. The administration of atropine was randomized into two groups: A or B (early protocol when atropine was administered at 10 and 20 mcg/kg/min of dobutamine, respectively) and C (standard protocol with atropine at 40 mcg/kg/min of dobutamine). Analysis of the effects of Beta-blockers was done regarding the behavior pattern of heart rate and blood pressure, test time, number of conclusive and inconclusive (negative sub-maximum test) results, total doses of atropine and dobutamine, and general complications.

Results

Beta-blocked patients who received early atropine (Group A&B) had a significantly lower double product (p = 0.008), a higher mean test time (p = 0.010) and required a higher dose of atropine (p = 0.0005) when compared to the patients in this group who were not Beta-blocked. The same findings occurred in the standard protocol (Group C), however the early administration of atropine reduced test time both in the presence and absence of this therapy (p = 0.0001). The patients with Beta-blockers in Group A&B had a lower rate of inconclusive tests (26%) compared to those in Group C (40%). Complications were similar in both groups.

Conclusion

The chronotropic response during dobutamine stress echocardiography was significantly reduced with the use of Beta-blockers. The early administration of atropine optimized the hemodynamic response, reduced test time in patients with or without Beta-blockers and reduced the number of inconclusive tests in the early protocol.

Predictive Value of Biphasic Response During Dipyridamole Echocardiography Test in the Low-risk Group of Patients After Acute Myocardial Infarction

To investigate whether biphasic response during dipyridamole echocardiography test (DET), which represents viable but potentially ischemic myocardium in the infarcted region, affects prognosis of patients after uncomplicated acute myocardial infarction, we performed high-dose DET in 80 consecutive patients younger than 65 years with first acute myocardial infarction and preserved left ventricular function. Patients were followed up for 27 +/- 12 months for new coronary events. According to DET results all patients were classified into 4 groups: group 1 consisted of 20 patients with biphasic response; group 2 included 14 patients with sustained improvement in regional contractility; group 3 consisted of 24 patients showing no change in contractility; and group 4 included 22 patients with worsening response. Cumulative survival free of total coronary events was significantly lower in group 1 patients compared with all other groups (P < .05). By multivariate Cox analysis biphasic response was the strongest independent predictor of stable angina pectoris (odds ratio = 12.1, P = .0002), followed by hyperlipoproteinemia (odds ratio = 5.9, P = .006). On the other hand, development of acute coronary syndromes could not have been predicted by actual clinical or DET parameters.

Stress radionuclide myocardial perfusion imaging detects more residual ischemia than stress echocardiography following acute myocardial infarction

OBJECTIVES

This investigation sought to compare the abilities of stress radionuclide myocardial perfusion imaging and stress echocardiography to detect residual ischemia in patients following acute myocardial infarction (MI).

BACKGROUND

Stress radionuclide myocardial perfusion imaging and stress echocardiography are both commonly used to assess patients (patients.) in the immediate post MI period. However, the relative value of these techniques in identifying post MI ischemia remains unclear.

METHODS

Eighteen patients. underwent both dipyridamole radionuclide perfusion imaging and dobutamine stress echocardiography on the same day or on consecutive days, 3-7 days following uncomplicated acute MI. Pts. who had an acute percutaneous intervention were excluded. Images were reviewed with clinical information available, but blinded to the opposing modality, for perfusion defects, wall motion abnormalities (WMA), and evidence of ischemia (reversible defect(s) on perfusion imaging, worsening WMA on stress echocardiography). Of the 18 patients, 11 subsequently underwent cardiac catheterization.

RESULTS

Perfusion imaging identified defects in 16 (89%) patients, of whom 15 (83% of total) were found to be ischemic. Stress echocardiography identified a fixed wall motion abnormality in 17 (94%) and ischemia in 8 (44%, p < 0.05 compared with perfusion imaging ischemia). Among 11 patients who underwent catheterization, there was a trend towards perfusion imaging identifying more ischemia in the territory of an obstructed (> or = 70%) vessel--100% (11/11) vs. 64% (7/11) for stress echocardiography (p = 0.09).

CONCLUSION

In the immediate post-infarction period, dipyridamole stress radionuclide myocardial perfusion imaging more often shows evidence of residual ischemia than dobutamine stress echocardiography.

Influence of contractile reserve and inducible ischaemia on left ventricular remodelling after acute myocardial infarction

OBJECTIVE

To assess the relative influence of contractile reserve and inducible ischaemia on subsequent left ventricular volume changes after myocardial infarction.

DESIGN

Left ventricular end diastolic and end systolic index volumes were calculated prospectively at discharge and at six months in 143 patients referred for early postinfarction dobutamine stress echocardiography. On the basis of their responses to this test, patients were divided into three groups: scar (n = 48; group 1); contractile reserve (n = 36; group 2); inducible ischaemia (n = 59; group 3).

RESULTS

At six months, the left ventricular end diastolic index volume decreased in group 2 (mean (SD), -3.9 (9.4) ml/m2) and increased in both group 1 (+2.8 (10.6) ml/m2, p = 0.009 v group 2) and group 3 (+7.5 (11.4) ml/m2, p < 0.0001 v group 2). The end systolic index volume decreased in group 2 (-4.9 (7.3) ml/m2) and increased in both group 1 (+1.3 (8.3) ml/m2, p = 0.0015 v group 2) and group 3 (+2.8 (8.9) ml/m2, p = 0.0002 v group 2). In multivariate analysis, the contractile reserve (hazard ratio 0.19, 95% confidence interval (CI) 0.14 to 0.47), inducible ischaemia (5.86, 95% CI 1.54 to 29.7), and end systolic index volume at discharge (1.04, 95% CI 0.99 to 1.11) were independent predictors of an increase in end diastolic index volume of > or = 15 ml/m2 at six months.

CONCLUSIONS

Contractile reserve and inducible ischaemia, as detected by early dobutamine stress echocardiography, identify patients with differences in long term left ventricular remodelling after acute myocardial infarction.

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.

Value of echocardiography in predicting future cardiac events after acute myocardial infarction

Short- and long-term survival after acute myocardial infarction mainly depends on three factors: the amount of myocardium that had become necrotic, the area of myocardium at further risk of becoming necrotic, and the patency of the infarct-related artery. Echocardiography is a low-cost, safe, bedside, repeatable tool, particularly useful for prognostic stratification after myocardial injury. Two-dimensional echocardiography analyzes left ventricular function, the most powerful predictor of survival immediately after acute myocardial infarction. Myocardial contrast echocardiography measures the infarct size and detects viable myocardium. Stress echocardiography stratifies patients with viable myocardium and/or multivessel coronary artery disease who need further diagnostic and therapeutic interventions. Transthoracic coronary Doppler ultrasonography assesses effective recanalization and coronary flow reserve of the left anterior descending coronary artery. Further technologic advances are needed to allow direct noninvasive measurement of flow by transthoracic Doppler ultrasonography in other coronary arteries.

Detection and clinical usefulness of a biphasic response during exercise echocardiography early after myocardial infarction

OBJECTIVE

The aim of this study was to determine the accuracy of exercise echocardiography (EE) for detecting infarct-related artery (IRA) stenosis and predicting functional recovery early after acute myocardial infarction (AMI).

BACKGROUND

Dobutamine stress echocardiography is widely used for identifying jeopardized myocardium. The clinical usefulness of a biphasic response detected during EE has never been investigated.

METHODS

A total of 114 consecutive patients with a first AMI and > or = 2 dyssynergic segments in the infarct-related territory underwent semi-supine continuous EE 6 +/- 2 days after AMI. Quantitative coronary angiography was performed in all patients after EE. A follow-up echocardiogram was obtained one month later.

RESULTS

Ninety-seven patients had significant (> or = 50%) IRA stenosis, and 26 had multivessel disease. Residual ischemia was identified in 77 patients (biphasic response in 62 and worsening response in 15). The sensitivity and specificity of ischemia during EE for predicting IRA stenosis were 75% and 76%, respectively. The sensitivity of a biphasic response was higher than the sensitivity of a worsening response (61% vs. 14%, p < 0.0001). Wall motion abnormalities induced in other vascular territories were specific (97%) and moderately sensitive (62%) for the detection of multivessel disease. Functional recovery was observed in 75 patients. Two independent variables predicted contractile recovery: contractile reserve during EE (p < 0.0001) and elective angioplasty of the IRA (p = 0.002). A biphasic response, but not sustained improvement, predicted reversible dysfunction (73% vs. 9%, p < 0.0001).

CONCLUSIONS

A biphasic response can be detected during exercise. Exercise echocardiography is an accurate tool for detecting IRA stenosis and predicting functional improvement early after AMI.

[Risk stratification after acute myocardial infarction]

In recent years, the characteristics of patients who suffer acute myocardial infarction without complications during hospitalization have changed. In addition, the range of non-invasive studies available for evaluating left ventricular systolic function, residual myocardial ischemia, and myocardial viability in these patients has improved. Left ventricular systolic function and residual ischemia should be evaluated in all patients before release. The non-invasive technique used (exercise test, echocardiography, nuclear cardiology, magnetic resonance imaging) depends on availability, experience, and results at each institution. Coronary arteriography should be performed in patients with significant ischemia or severe left ventricular systolic dysfunction in non-invasive studies. In these cases coronary angiography must be performed to determine if coronary arteries are suitable for revascularization before performing a test of myocardial viability.

Use of pharmaceuticals in noninvasive cardiovascular diagnosis

A number of pharmaceuticals are employed as diagnostic agents for cardiovascular diseases. Four groups of agents are reviewed here: 1) vasoactive substances employed as adjuncts to physical maneuvers in diagnosis of structural heart disease; 2) vasodilators used to produce heterogeneity of coronary flow; 3) sympathomimetic agents simulating the effects of exercise on the heart for the purpose of detection of coronary artery stenosis; and 4) ultrasonic contrast agents used to enhance myocardial imaging for the assessment of segmental wall motion. In the first group are amyl nitrate, a vasodilator, and methoxamine and phenylephrine, both vasopressors. The vasodilators of the second group are dipyridamole and adenosine. When combined with scintigraphic perfusion imaging or with echocardiographic assessment of segmental wall motion, these agents can detect single- or multiple-vessel coronary artery disease with sensitivity and specificity comparable to submaximal exercise. They are especially useful for preoperative risk assessment before noncardiac surgery. The sympathomimetic agents of the third group, dobutamine and arbutamine, increase myocardial contractility and heart rate, and dilate the peripheral vasculature. As with the vasodilators, when combined with nuclear or echocardiographic techniques they are equivalent to exercise in detection of coronary disease. They are especially useful in patients with bronchospastic disease and for assessment of myocardial viability. Agents from groups 2 and 3 have acceptable side-effect and safety profiles. The last group reviewed includes echocardiographic contrast agents that, in this investigative setting, are employed to enhance detection of segmental wall motion when used with agents from groups 2 and 3.

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.

Early dipyridamole stress myocardial SPECT to detect residual stenosis of infarct related artery: comparison with coronary angiography and fractional flow reserve

BACKGROUND

The detection of residual stenosis of infarct related artery (IRA) at early stage after acute myocardial infarction (AMI) is crucial in clinical decision making for interventional revascularization. The aim of this study was to evaluate the relevancy of early dipyridamole stress myocardial SPECT to detect functionally and luminologically significant residual stenosis of IRA after AMI.

METHODS

Twenty five consecutive patients (M:F = 19:6, age: 56 +/- 13 yrs) with AMI underwent SPECT and coronary angiography within 5 days of the attack. Infarct related arteries with FFR < 0.75 and diameter stenosis (DST) > 70% were regarded to have functionally and morphologically significant residual stenosis. Reversible perfusion defect was defined if there was improvement of the perfusion score more than one grade in infarct segments on rest images of SPECT compared with stress images.

RESULTS

Mean FFR and DST were 0.76 +/- 0.14 and 74 +/- 15%. SPECT showed no significant correlation with both FFR and DST with Kendall's coefficiency of 0.28 (p = 0.05) and 0.13 (p = 0.35). The sensitivity and specificity of SPECT to detect functionally and morphologically significant residual stenosis were 92%, 31% and 83%, 29%.

CONCLUSION

The early dipyridamole stress myocardial SPECT after AMI does not seem to be a useful non-invasive test for the detection of functionally and luminologically significant residual stenosis of IRA.

Utility and limitation of treadmill exercise echocardiography for detecting significant coronary stenosis in infarct-related arteries in patients with healed myocardial infarction

This clinical study examines the diagnostic accuracy of exercise echocardiography for detecting significant coronary stenoses in infarct-related arteries in patients with healed myocardial infarction. Quantitative coronary angiography and exercise echocardiography using treadmill testing were performed within 2 weeks of each other in 123 patients with a prior myocardial infarction. Coronary lumen diameter stenosis > or =50% by quantitative coronary angiography and the lack of a hyperdynamic response on exercise echocardiography was considered significant. For detection of infarct-related coronary lesions, treadmill exercise echocardiography was highly sensitive (91%) but less specific (59%) than for detection of non-infarct-related artery lesions. The 2 groups of patients with large and small infarct sites had similar sensitivity for detection of residual stenosis of the infarct-related artery (88% vs 96%, p = NS); however, the specificity of the small infarct sites for this purpose was significantly higher than that of the large infarct sites (86% vs 33%, p < 0.01). When remote ischemia was detected on exercise echocardiography, the specificity of exercise echocardiography was significantly lower (33% vs 70%, p < 0.05) than when remote ischemia was not present. Thus, although there is high sensitivity, the specificity of treadmill exercise echocardiography for detecting infarct-related artery lesions is limited. However, high specificity is maintained when the infarct size is small and/or remote ischemia is not present.

Reliability of fractional flow reserve measurements in patients with associated microvascular dysfunction: importance of flow on translesional pressure gradient

Fractional flow reserve (FFR) has been applied with success as a lesion-specific functional indicator of stenosis severity, at least in patients with normal microcirculation. This study sought to assess the reliability of FFR calculations in patients with associated microvascular dysfunction (e.g., post myocardial infarction, or post-MI). First, the effect of coronary flow changes on translesional pressure gradient was assessed. Therefore, intracoronary pressure and flow was recorded simultaneously across 19 non-infarct-related lesions (both pre- and postinterventional lesions with a mean diameter stenosis of 47% +/- 12%). Measurements were performed by means of a pressure and Doppler wire during maximal hyperemia and also during submaximal hyperemia induced by low-dose adenosine. The drop of coronary flow from 48 +/- 23 ml/min during maximal hyperemia to 36 +/- 18 ml/min during submaximal hyperemia was associated with a small decrease in translesional pressure gradient (from 22 +/- 12 mm Hg to 19 +/- 12 mm Hg; P = 0.02) and a small increase in the mean distal/arterial pressure ratio (Pd/Pa) going from 77% +/- 11% to 81% +/- 11% (P = 0.003). Then, intracoronary pressure and flow measurements were compared across 21 non-infarct-related lesions vs. 22 matched infarct-related lesions. For a similar angiographic stenosis severity (% DS = +/- 44%), maximal flow was 48 +/- 22 ml/min in the non-infarct arteries and 37 +/- 26 ml/min in the infarct arteries (P = 0.03), confirming the presence of severe microvascular dysfunction in infarct regions. Similar to the earlier findings, this hyperemic flow reduction in MI patients was associated with a small increase of FFR (= Pd/Pa): 79% +/- 12% in no MI vs. 83% +/- 12% in MI patients (P = 0.3). A reduction of hyperemic flow by +25%, [correction] such as can be found in patients with severely impaired microvascular function, has a limited effect on FFR calculations (+ 5%). This finding allows the application of standard FFR calculations in a more general population of ischemic heart disease, including patients with recent MI.

Pharmacological stress agents for evaluation of ischemic heart disease

Ischemic heart disease is the leading cause of death in the developed countries for those older than 65 years of age. In patients suspected to have coronary artery disease a stress test should be performed to identify the vulnerability of the myocardium to ischemia. As a rule of thumb, the evaluation of coronary artery disease is best done by exercise stress test. In patients who are not able to exercise adequately, pharmacological stress agents are used. The commonly used agents are the coronary vasodilators, adenosine and dipyridamole and the catecholamines, dobutamine and arbutamine. These agents are combined with imaging techniques to increase the sensitivity and specificity of the test. These agents have been widely used and have an excellent safety profile. Another advantage in using pharmacological stress agents is that they do not affect the image quality, especially with echocardiography and magnetic resonance imaging. Ongoing developments hold promise for safer and more reliable pharmacological stress agents in the future.

Dobutamine stress echocardiography versus quantitative technetium-99m sestamibi SPECT for detecting residual stenosis and multivessel disease after myocardial infarction

OBJECTIVE

To compare the relative accuracy of dobutamine stress echocardiography (DSE) and quantitative technetium-99m sestamibi single photon emission computed tomography (mibi SPECT) for detecting infarct related artery stenosis and multivessel disease early after acute myocardial infarction.

DESIGN

Prospective study.

SETTING

University hospital.

METHODS

75 patients underwent simultaneous DSE and mibi SPECT at (mean (SD)) 5 (2) days after a first acute myocardial infarct. Quantitative coronary angiography was performed in all patients after imaging studies.

RESULTS

Significant stenosis (> 50%) of the infarct related artery was detected in 69 patients. Residual ischaemia was identified by DSE in 55 patients and by quantitative mibi SPECT in 49. The sensitivity of DSE and mibi SPECT for detecting significant infarct related artery stenosis was 78% and 70%, respectively, with a specificity of 83% for both tests. The combination of DSE and mibi SPECT did not change the specificity (83%) but increased the sensitivity to 94%. Mibi SPECT was more sensitive than DSE for detecting mild stenosis (73% v 9%; p = 0.008). The sensitivity of DSE for detecting moderate or severe stenosis was greater than mibi SPECT (97% v 74%; p = 0.007). Wall motion abnormalities with DSE and transient perfusion defects with mibi SPECT outside the infarction zone were sensitive (80% v 67%; NS) and highly specific (95% v 93%; NS) for multivessel disease.

CONCLUSIONS

DSE and mibi SPECT have equivalent accuracy for detecting residual infarct related artery stenosis of >/= 50% and multivessel disease early after acute myocardial infarction. DSE is more predictive of moderate or severe infarct related artery stenosis. Combined imaging only improves the detection of mild stenosis.

Clinical and angiographic correlates of dobutamine-induced wall motion patterns after myocardial infarction

The ability of different dobutamine-induced wall motion patterns to define the anatomic status of the infarct-related artery (IRA) was evaluated in 159 patients who underwent dobutamine stress echocardiography (DSE) and coronary angiography 10 +/- 2 and 18 +/- 3 days, respectively, after hospital admission. The DSE result was classified as: (1) biphasic: improvement with a low dose followed by deterioration with a high dose; (2) worsening: direct deterioration at low or high doses; (3) sustained improvement: improvement with a low dose that was maintained at high dose; and (4) no change: no change during the entire protocol. A diameter narrowing >70% (50% for the left main stem) of major coronary arteries indicated a severe lesion. Angiograms were classified according to the jeopardy score and collateral circulation graded according to Rentrop's classification. DSE was positive in 92 patients (22 had biphasic results and 70 had worsening results) and negative in 67 patients (14 had sustained improvement and 53 had no changes). Biphasic response was associated with more frequent anterior infarction (p <0.05) and higher resting (p <0.001) and peak (p <0.01) wall motion score indexes. The IRA was totally occluded in 4 of the 92 patients (4%) with positive (worsening pattern) and 12 of the 67 patients (18%) with negative (no change pattern) tests. The biphasic pattern was associated with the highest jeopardy score and was significantly (p <0.05) more specific (100%) compared with worsening (78%) in identifying a severe stenosis of the IRA. The combination of ischemic patterns provided a significantly superior sensitivity (p <0.0001). Logistic regression analysis identified the biphasic pattern as the only significant predictor. Conversely, the prediction of total occlusion of the IRA was poor. Sustained improvement was the most specific (100%) predictor of absence of severe stenosis of the IRA, whereas the combination with no change pattern provided a significantly superior sensitivity (p <0.0001). Thus, DSE effectively predicts the residual stenosis of the IRA. In particular, the biphasic response has an excellent specificity and positive predictive value and is the only significant predictor among clinical and echocardiographic variables.

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.

[Evaluation of the safety of stress echocardiography in Spain and Portugal]

INTRODUCTION. There are few studies that evaluate the safety of stress echocardiography with discordant results. They are done in well-trained centers with highly selected populations leading to selection bias.

OBJECTIVE

To assess the safety of the different modalities of stress echocardiography in Spain and Portugal.

METHOD

Severe complications were retrospectively analyzed during the stress echocardiography performed in 29 hospitals in Portugal and Spain, from the beginning of their activity to September, 1999. In this period 22,105 stress echocardiograms were performed: 10,975 exercise echos, 2,969 low dose dobutamine echos, 6,832 high dose dobutamine echocardiograms, 1,276 dypiridamole echocardiograms, 41 paced echocardiograms and 12 with adenosine. A complication was defined as severe when it was life-threatening or led to hospital admission.

RESULTS

We registered 26 complications, one death, 3 ventricular fibrillations, 10 sustained ventricular tachycardias, 2 complete atrioventricular blocks, 6 acute myocardial infarctions, 2 ruptures of the free wall or ventricular septal defects, 1 transient ischemic attack and 1 severe symptomatic hypotension. We had one severe complication for every 2,743 exercise stress, 1 every 1,231 dypiridamole, 1 every 325 high dose dobutamine without any complications with low dose dobutamine stress. We found a relationship between experience in dobutamine stress echocardiography and the frequency of complications. Three complications appeared once the test was finished.

CONCLUSIONS

The stress echocardiography is a safe technique, but not harmless. The exercise stress echo is the safest of all the modalties of stress echocardiography. There is a relation between experience and the number of complications.

Prognostic interaction between viability and residual myocardial ischemia by dobutamine stress echocardiography in patients with acute myocardial infarction and mildly impaired left ventricular function

Dobutamine stress echocardiography (DSE) accurately detects viable myocardium and residual ischemia in patients with acute myocardial infarction (AMI). The prognostic interaction of viability and ischemia has not been completely clarified in these patients. This study assesses the long-term effect of viability, ischemia, or their combination on survival in patients with AMI and mildly impaired left ventricular (LV) function. Four hundred eleven patients (age 57 +/- 9 years) underwent predischarge DSE (up to 40 microg/kg/min plus atropine if needed) after uncomplicated AMI and were prospectively followed for 23 months (range 1 to 78). According to DSE findings, patients were divided into 4 groups: viability only, ischemia only, combination of viability and ischemia, and scar. Adverse outcome occurred in 64 patients: 34 patients had hard events (9 cardiac deaths, 25 nonfatal AMI) and 30 patients had unstable angina requiring hospitalization. The combination of viability and ischemia, diabetes mellitus, and non-Q-wave AMI were significant predictors of all events at univariate and multivariate analysis. The same variables were also univariate predictors of hard events, but multivariate analysis indicated only the combination of viability and ischemia and diabetes as independent predictors. The event-free survival of patients with combined viability and ischemia was significantly lower (hazard ratio 3 [95% confidence interval 1.8 to 11]) compared with patients with ischemia only. Thus, viability and ischemia show a significant adverse prognostic interaction in patients with AMI and preserved LV function.

Ultrasonic tissue characterization with integrated backscatter during inotropic stimulation

Ultrasonic tissue characterization with integrated backscatter is an objective method to quantitatively define the physical state of the myocardium. To determine if backscatter imaging during inotropic stimulation could be used objectively to determine the myocardial viability and ischemia in patients with ischemic heart disease, the backscatter changes were examined in 23 patients with myocardial infarction during dobutamine stress two-dimensional (2-D) echocardiography. Coronary angiography was performed within 1 to 2 days after the stress test. The results of this study demonstrated that changes in backscatter variability correlated significantly with the wall motion changes in stress echocardiography during dobutamine infusion (p < 0.0001). In addition, it was shown that the backscatter changes were significantly different in various types of myocardial tissue. In 23 healthy control segments, the ultrasonic backscatter variability was preserved and unchanged during inotropic stimulation (p = NS). In 15 viable infarct zones, restoration or an increase in backscatter variability during low-dose dobutamine infusion was noted, this being lost when ischemia developing during high-dose dobutamine infusion (p < 0.01). In 9 nonviable infarct zones, the phase-weighted variation was usually < or = 0 and did not change significantly during inotropic stimulation, regardless of the patency of the infarct-related arteries. In 15 remote ischemic myocardial zones, the backscatter variability was preserved at the baseline level, did not change during low-dose dobutamine infusion, but decreased significantly during high-dose dobutamine stress (p < 0.01). In conclusion, dobutamine stress tissue characterization could offer an objective approach for the detection of myocardial viability and ischemia, and might be a useful adjunct to the conventional stress echocardiography.

Safety and efficacy of an accelerated dobutamine stress echocardiography protocol in the evaluation of coronary artery disease

Although dobutamine requires up to 10 minutes to achieve steady state, dobutamine stress echocardiography is routinely performed using stepwise increments at 3-minute intervals. Consequently, the full effect of any infusion rate is not attained before the dobutamine dose is advanced to the next level. This study sought to test the safety and efficiency of high-dose continuous dobutamine infusion. One hundred consecutive patients underwent an accelerated protocol using a constant infusion of 50 microg/kg/min. In the absence of a stress echocardiographic end point (>/=85% of maximal predicted heart rate, new wall motion abnormalities, hypotension, arrhythmia, or intolerable symptoms), dobutamine infusion was discontinued at 10 minutes. Hemodynamic responses and adverse effect profile were compared with 100 patients who underwent a standard stepwise dobutamine stress protocol. Peak heart rate (140 +/- 16 vs 140 +/- 19 beats/min, p = 0.95) and systolic blood pressure (169 +/- 32 vs 162 +/- 31 mm Hg, p = 0.08) were similar in both protocols. Accelerated dobutamine administration produced a rapid increase in heart rate (12.5 +/- 6.2 vs 5.7 +/- 2.6 beats/min, p <0.001), and a substantial reduction in test duration (6.4 +/- 2.4 vs 12.9 +/- 3.0 minutes, p <0.001). The mean weight-adjusted cumulative dobutamine dose was lower in the accelerated protocol group (320 +/- 111 vs 353 +/- 133 microg/kg, p = 0.016). No significant differences were noted between the 2 groups with respect to various side effects. These data demonstrate that a high-dose, single-stage dobutamine echocardiographic stress protocol is a feasible, well-tolerated alternative to standard dobutamine stress echocardiography, and results in a substantial reduction in test time while maintaining a low complication rate.

Dobutamine-atropine stress echocardiography and dipyridamole sestamibi scintigraphy for the detection of coronary artery disease: limitations and concordance

OBJECTIVES

We sought to compare dobutamine-atropine stress echocardiography (DASE) and dipyridamole Technetium 99-m (Tc-99m) sestamibi single photon emission computed tomography (SPECT) scintigraphy (DMIBI) for detecting coronary artery disease (CAD).

BACKGROUND

Both DASE and DMIBI are effective for evaluating patients for CAD, but their concordance and limitations have not been directly compared.

METHODS

To investigate these aims, patients underwent multistage DASE, DMIBI and coronary angiography within three months. Dobutamine-atropine stress echocardiography and stress-rest DMIBI were performed according to standard techniques and analyzed for their accuracy in predicting the extent of CAD. Segments were assigned to vascular territories according to standard models. Angiography was performed using the Judkin's technique.

RESULTS

The 183 patients (mean age: 60 +/- 11 years, including 50 women) consisted of 64 patients with no coronary disease and 61 with single-, 40 with two- and 18 with three-vessel coronary disease. Dobutamine-atropine stress echocardiography and DMIBI were similarly sensitive (87%, 104/119 and 80%, 95/119, respectively) for the detection of CAD, but DASE was more specific (91%, 58/64 vs. 73%, 47/64, p < 0.01). Sensitivity was similar for the detection of CAD in patients with single-vessel disease (84%, 51/61 vs. 74%, 45/61, respectively) and multivessel disease (91%, 53/58 vs. 86%, 50/58, respectively). Multiple wall motion abnormalities and perfusion defects were similarly sensitive for multivessel disease (72%, 42/58 vs. 66%, 38/53, respectively), but, again, DASE was more specific than DMIBI (95%, 119/125 vs. 76%, 95/125, respectively, p < 0.01). Dobutamine-atropine stress echocardiography and DMIBI were moderately concordant for the detection and extent of CAD (Kappa 0.47, p < 0.0001) but were only fairly (Kappa 0.35, p < 0.001) concordant for the type of abnormalities (normal, fixed, ischemia or mixed).

CONCLUSIONS

Dobutamine-atropine stress echocardiography and DMIBI were comparable tests for the detection of CAD. Both were very sensitive for the detection of CAD and moderately sensitive for the extent of disease. The only advantage of DASE was greater specificity, especially for multivessel disease. Dobutamine-atropine stress echocardiography may be advantageous in patients with lower probabilities of CAD.

Diagnostic and prognostic use of stress echocardiography in stable patients

Stress echocardiography is an effective diagnostic and prognostic technique in stable patients with known or suspected coronary artery disease (CAD), myocardial infarction, or chronic left ventricular dysfunction and those undergoing noncardiac surgery. Stress echocardiography is sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events regardless of the clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Stress echocardiography provides incremental prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable to that from radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for one-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.

Dobutamine stress echocardiography: safety in diagnosing coronary artery disease

Dobutamine stress echocardiography is considered a relatively well-tolerated diagnostic modality, effective in the management of patients with known or suspected coronary artery disease. Adverse effects during testing are relatively frequent, precluding the achievement of a diagnostic end-point in about 5 to 10% of tests. These adverse effects, mostly tachyarrhythmias and arterial hypotension, are usually minor and self limiting. However, severe life-threatening complications, as well as death, also occur. By analysing Medline-quoted literature up to March 1999, we found 35 original studies from a single institution with more than 100 patients, as well as 2 multicentre studies, concerning the feasibility and safety of dobutamine stress echocardiography. In a cumulative total of 26438 tests performed, 79 life-threatening complications (such as acute myocardial infarction, asystole, ventricular fibrillation, sustained ventricular tachycardia or severe symptomatic hypotension) have been reported, giving an incidence of 1 severe adverse reaction per every 335 examinations. In addition, 29 isolated case reports have been published describing life-threatening complications during dobutamine echocardiography. In case reports, 2 deaths have been described, both due to acute cardiac rupture in patients with recent inferior myocardial infarction. Severe adverse reactions during dobutamine echocardiography can be ischaemia independent, and are independent of operator experience and are unpredictable; some complications can be late occurring and long lasting. As a consequence, the procedure must be clearly indicated, written informed consent has to be obtained from the patient, an attending physician must be present during testing, and long term observation of outpatients is useful in order to manage late complications. In conclusion, while the safety of dobutamine stress echocardiography was reported to be outstanding in early reports, further experience presents a substantially more worrying picture. This must be taken into account by both physicians and patients when assessing the risk-benefit profile of the procedure.

The comparable diagnostic accuracies of dobutamine-stress and dipyridamole-stress echocardiographies: a meta-analysis

BACKGROUND

Dobutamine-stress and dipyridamole-stress echocardiographies are widely used for pharmacological stress echocardiography, with wide geographical variations.

OBJECTIVE

To assess whether evidence derived from the literature indicates or disapproves that either stress modality confers diagnostic superiority.

METHODS

We performed a meta-analysis of peer-reviewed literature of published trials with head-to-head comparison, on the same population, of high-dose (0.84 mg/kg) dipyridamole-stress versus high-dose (up to 40 micrograms/kg per min) dobutamine-stress echocardiography. Data from 12 studies performed in 12 institutions in seven countries were analysed. Angiographic information about 818 patients was considered.

RESULTS

The diagnostic accuracies of the two tests were similar (631 of 818, 77%, for dipyridamole versus 654 of 818, 80%, for dobutamine, NS). Overall sensitivities were 403 of 568 (71%) for dipyridamole and 437 of 568 (77%) for dobutamine (P < 0.05). Sensitivities for patients with single-vessel disease were 177 of 275 (64%) for dipyridamole and 203 of 275 (74%) for dobutamine (P < 0.05). Sensitivities for patients with multivessel disease were 162 of 203 (80%) for dipyridamole and 163 of 203 (80%) for dobutamine (NS). Specificities were 232 of 250 (93%) for dipyridamole and 217 of 250 (87%) for dobutamine (P < 0.05). Data from an additional 26 studies with dipyridamole alone and 47 studies with dobutamine alone were analysed. The diagnostic accuracies were 80% for dipyridamole (n = 2038 patients; 95% confidence interval 75-82%) and 82% for dobutamine (n = 4264 patients; 95% confidence interval 79-84%).

CONCLUSION

High-dose dobutamine-stress and high-dose dipyridamole-stress echocardiographies have comparable diagnostic accuracies, with a slightly higher sensitivity with dobutamine and a slightly higher specificity with dipyridamole.

Acute cardiac rupture during dobutamine-atropine echocardiography stress test

We report an acute cardiac rupture during dobutamine-atropine echocardiography stress test on the sixth day after admission for an inferoposterior acute myocardial infarction complicated with mild pericardial effusion.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Diagnostic and Prognostic Use of Stress Echocardiography and Radionuclide Scintigraphy

Stress echocardiography and radionuclide scintigraphy are effective diagnostic and prognostic techniques in patients with known or suspected coronary artery disease (CAD), myocardial infarction (MI), chronic left ventricular dysfunction (LVD), and those undergoing noncardiac surgery. Both are sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events irrespective of clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Both provide incremental diagnostic and prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable with radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for single-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.