Conventional Stress Echocardiography Research Articles

Abstract 11702: Development of Artificial Intelligence-Based Slow-Motion Echocardiography and Clinical Usefulness for Evaluating Regional Wall Motion Abnormalities

Introduction: Improvement in accuracy and image readability of stress echocardiography needs to be addressed, given that the accuracy depends on the physicians’ experience and image quality. The study aimed to develop an artificial intelligence (AI) based slow-motion echocardiography by inter-image interpolation and evaluate the clinical usefulness for detecting regional wall motion abnormalities (RWMAs). Methods: An AI-based image interpolation pipeline was developed with the optical flow calculation between echocardiographic images and predicting in-between images. In a cohort of patients with RWMA (n=25) and healthy volunteers (n=25), the accuracy for detecting RWMAs and image-reliabilities among four cardiologists was evaluated using slow-motion and conventional exercise stress echocardiography. Results: The development of slow-motion echocardiography were successfully performed at any arbitrary-time steps (e.g., 0.125x, 0.25x, and 0.5x). The accuracy for detecting RWMAs was numerically improved, while not statistically significant (87.5% in slow-motion echocardiography vs 81.0% in conventional stress echocardiography, odds ratio: 1.43 (95% confidence interval 0.78-2.62, p=0.25). Inter-reader agreement analysis demonstrated the level of agreements (Fleiss’s Kappa) for detecting RWMAs was 0.66 (95%CI: 0.55-0.77) in slow-motion echocardiography, and 0.53 (95%CI: 0.42-0.65) in conventional stress echocardiography. As for the four-point scale subjectively-evaluated image readability, the mean score was significantly improved using slow-motion echocardiography (2.11±0.73vs 1.70±0.78, p<0.001). Conclusions: Slow-motion echocardiography was successfully developed. There was no significant improvement in the accuracy for detecting RWMAs using the developed slow-motion echocardiography, while the image readability and inter-reader agreement were improved.

Change in Lung Fluid Volume during Exercise in Patients with Exercise-Induced Mitral Regurgitation

Exercise-induced mitral regurgitation (MR) can be diagnosed during stress echocardiography testing. Remote dielectric sensing (ReDSTM) is a noninvasive electromagnetic-based modality to measure lung fluid levels. The change in lung fluid levels in patients with MR during stress echocardiography remains unknown. Patients with symptomatic MR at baseline and suspected worsening exercise-induced MR underwent stress echocardiography. ReDS values were measured before and after the tests. A total of four patients (ages ranging between 74 and 84 years old, three women) underwent stress echocardiography testing using a bicycle ergometer. In patient A, MR effective regurgitant orifice area (EROA) remained unchanged and ReDS values decreased. EROA increased significantly with a small incremental change in ReDS values in patient B and patient C, who underwent valve repair with MitraClip later. Patient D had a mild increase in MR EROA but a considerable increase in ReDS values (from 22% to 32%), and eventually received valve repair with MitraClip. The ReDS system may be a complementary tool to conventional stress echocardiography in the evaluation of clinically significant MR and considering mitral valve intervention.

Regadenoson Mycardial Contrast Echocardiography Perfusion Imaging for Detection of Allograft Coronary Vasculopathy

<h3>Purpose</h3> Due to the often asymptomatic nature of cardiac allograft vasculopathy (CAV) serial surveillance is recommended for all cardiac transplant (OHT) recipients. Ideally, CAV surveillance should be non-invasive, not involve ionizing radiation, and discriminate diffuse CAV from focal obstructions. We hypothesized that vasodilator stress myocardial contrast echocardiography (MCE) perfusion imaging can non-invasively detect microvascular impact of diffuse or focal CAV. <h3>Methods</h3> The study was a retrospective, single center analysis of OHT recipients undergoing MCE between 1/20 and 10/20 (n=11). MCE at rest and after regadenoson was performed using a continuous infusion of lipid-shelled microbubbles. Images were analyzed by evaluating time-intensity after a destructive pulse sequence in all vascular territories. MCE data were correlated with wall motion assessment by conventional stress echocardiography and invasive coronary angiography (ICA). Grading of MCE as normal, mild, severe; and focal vs. diffuse was performed by one experienced reviewer in a blinded fashion. <h3>Results</h3> Mean age was 63 ± 3.3 years post OHT, at an average of 10.8 ± 3.3 years post OHT. Severe perfusion abnormalities during MCE were able to distinguish high grade CAV (2+) from low grade CAV (0-1) utilizing ICA as the gold standard. While stress echocardiographic wall motion assessment failed to indicate early CAV grade 1, abnormal MCE perfusion was found in 3 of 7 cases with angiographic CAV grade 1. <h3>Conclusion</h3> MCE is a practical, non-invasive perfusion imaging technique that may be useful for detecting significant CAV in OHT recipients. Perfusion deficits correlate with significant coronary artery stenosis identified by standard stress echocardiography and ICA, and may identify diffuse small vessel disease more effectively than current noninvasive techniques. Larger, prospective studies are needed to support this hypothesis and ultimately provide a rationale for routine use of MCE for CAV surveillance.

Differences in patient outcomes after conventional versus real time perfusion stress echocardiography in men versus women: a prospective randomised trial

ObjectiveThe purpose of our study was to determine whether sex affects the predictive value of perfusion and wall motion imaging obtained with real time myocardial contrast echocardiography (RTMCE) when compared...

Prospective Randomized Comparison of Conventional Stress Echocardiography and Real-Time Perfusion Stress Echocardiography in Detecting Significant Coronary Artery Disease

Although retrospective studies have suggested that myocardial perfusion and wall motion analysis with real-time myocardial contrast echocardiography (RTMCE) improves the detection of coronary artery disease (CAD) during dobutamine or exercise stress echocardiography, a prospective randomized comparison with conventional stress echocardiography that did not use RTMCE has not been performed. A total of 1,776 patients with preserved resting left ventricular wall motion undergoing dobutamine or exercise stress echocardiography for suspicion of CAD were randomized to either non-RTMCE, for which contrast was used only for the approved indication of enhancing left ventricular opacification, or RTMCE, for which contrast infusion was used in all cases to examine both wall motion and myocardial perfusion. Comparisons in test positivity, and positive predictive value in those subsequently referred for quantitative coronary angiography, were performed. Patients randomized to RTMCE had significantly higher test positivity (22% for RTMCE vs 15% with non-RTMCE, P= .0002). The increased test positivity occurred without a difference in positive predictive value in predicting >50% diameter stenoses by quantitative coronary angiography (67% for non-RTMCE, 73% for RTMCE). The mechanism for increased detection of CAD with RTMCE was mostly due to the detection of subendocardial wall thickening abnormalities that would have gone undetected when examining transmural wall thickening. RTMCE improves the detection of CAD during dobutamine and exercise stress echocardiography, mainly by the detection of subendocardial ischemia.

Role of Right Ventricular Wall Motion Abnormalities in Risk Stratification and Prognosis of Patients Referred for Stress Echocardiography

The purpose of this study was to evaluate the prognostic value of assessing right ventricular (RV) wall motion abnormalities during stress echocardiography (SE). The results of SE are usually interpreted based on wall motion abnormalities of the left ventricle (LV). There is increasing recognition of the prognostic importance of RV. However, RV is still a "forgotten" chamber during routine SE. We evaluated 2,703 patients referred for SE. The LV was evaluated on a 16-segment model 5-point scale and the RV was evaluated on a 3-segment model 5-point scale for wall motion abnormalities. An abnormal RV or LV was defined as one with new (ischemic) or fixed (infarction) wall motion abnormalities. Follow-up (2.7 +/- 1.0 years) for confirmed myocardial infarction and cardiac death (n = 122) were obtained. An abnormal RV was seen in 112 patients (4%). In the presence of an abnormal LV, patients with abnormal RV had a worse prognosis than those with normal RV. Abnormal RV was a significant predictor of events (adjusted hazard ratio 2.69, 95% confidence interval 1.22 to 5.92; p = 0.014) independent of LV ischemia and ejection fraction. A forward conditional Cox model showed that peak RV wall motion score index provided incremental prognostic value over rest and conventional SE variables (global chi-square increased from 141.4 to 161.8 to 197.0; p < 0.0001 and p = 0.006, respectively). In patients referred for SE, RV wall motion analysis provides prognostic value independent of LV ischemia and ejection fraction and provides incremental value over rest and conventional SE variables. Right ventricular wall motion analysis should be routinely performed in patients referred for SE for effective risk stratification.

Quantitative Real-time 3-Dimensional Stress Echocardiography: A Preliminary Investigation of Feasibility and Effectiveness

Use of rapidly emerging real-time 3-dimensional (3D) echocardiography promises to improve the diagnostic accuracy of stress echocardiography (SE). However, widespread acceptance of 3D-SE, based on real-time 3D echocardiography, is hampered in part by lack of efficient, accurate, and objective analysis tools. We propose novel algorithms for interactive visualization, registration (alignment), and quantitative analysis of prestress and poststress real-time 3D echocardiography to facilitate an objective diagnosis. In a preliminary evaluation, two experts independently performed wall-motion analysis in 15 patients with known/suspected coronary artery disease, using the novel quantitative 3D-SE methods. Compared with previously reported values for conventional 2-dimensional SE, improved interexpert agreement (kappa = 0.85) was observed for segment-wise classification of normal/abnormal wall motion using the novel 3D-SE methods. Overall, 6 of 6 patients with abnormal myocardial segments were correctly identified by both experts with 3D-SE, compared with 4 of 6 with conventional 2-dimensional SE. Initial results are promising and indicate the feasibility and potential of our proposed quantitative 3D-SE methodologies for improving diagnosis of wall-motion abnormalities.

Real-time myocardial perfusion imaging for pharmacologic stress testing: Added value to single photon emission computed tomography

Little is known about the incremental value of real-time myocardial contrast echocardiography (MCE) as an adjunct to pharmacologic stress testing. This study was performed to evaluate the diagnostic value of MCE to detect abnormal myocardial perfusion by technetium Tc 99m sestamibi-single photon emission computed tomography (SPECT) and anatomically significant coronary artery disease (CAD) by angiography. Myocardial contrast echocardiography was performed at rest and during vasodilator stress in consecutive patients (N = 120) undergoing SPECT imaging for known or suspected CAD. Myocardial opacification, wall motion, and tracer uptake were visually analyzed in 12 myocardial segments by 2 pairs of blinded observers. Concordance between the 2 methods was assessed using the kappa statistic. Of 1356 segments, 1025 (76%) were interpretable by MCE, wall motion, and SPECT. Sensitivity of wall motion was 75%, specificity 83%, and accuracy 81% for detecting abnormal myocardial perfusion by SPECT (kappa = 0.53). Myocardial contrast echocardiography and wall motion together yielded significantly higher sensitivity (85% vs 74%, P < .05), specificity of 83%, and accuracy of 85% (kappa = 0.64) for the detection of abnormal myocardial perfusion. In 89 patients who underwent coronary angiography, MCE and wall motion together yielded higher sensitivity (83% vs 64%, P < .05) and accuracy (77% vs 68%, P < .05) but similar specificity (72%) compared with SPECT for the detection of high-grade, stenotic (> or = 75%) coronary lesions. Assessment of myocardial perfusion adds value to conventional stress echocardiography by increasing its sensitivity for the detection of functionally abnormal myocardial perfusion. Myocardial contrast echocardiography and wall motion together provide higher sensitivity and accuracy for detection of CAD compared with SPECT.

Real-time myocardial contrast dobutamine stress echocardiography in coronary stenosis

Background Simultaneous wall motion and myocardial perfusion analysis could offer advantages over either method alone. Diagnostic utility of combining these parameters during dobutamine stress echocardiography is evaluated in this study. Methods Myocardial contrast dobutamine stress echocardiography was performed on thirty-eight patients with single or double vessel coronary artery stenosis of > 50%. Two-dimensional standard wall motion images were acquired at baseline, low, intermediate and peak stages of dobutamine stress echocardiography. Contrast enhanced wall motion and perfusion were assessed with Cadence Contrast Imaging (Sequoia C256, Acuson) and Optison infusion (GE Healthcare) at baseline and peak stages of the same protocol. Perfusion was analysed by identification of contrast defects and by measuring contrast replenishment time after destructive ultrasound pulses. Results The group consisted of 28 males and 10 females, mean age 60.9 ± 9.7 years. Fifty-four out of one hundred and fourteen coronary arteries were affected by stenoses > 50%. Standard wall motion analysis was assessable in 37 cases, one of which was inconclusive, while contrast wall motion and perfusion were assessable in 32 cases. Accuracy for coronary stenosis was 84% for standard wall motion (108 coronary territories), 82% for contrast wall motion (96 territories), 69% for peak stress contrast defects (83 territories), 91% for combined peak stress contrast defects and increased contrast replenishment time (85 territories), and 90% for all contrast modalities combined (96 territories). Conclusion Combined wall motion and real-time perfusion assessment during dobutamine stress is feasible and at least equivalent to conventional stress echocardiography for detection of significant coronary stenosis.

PII: S0022-3999(05)00154-6

Use of rapidly emerging real-time 3-dimensional (3D) echocardiography promises to improve the diagnostic accuracy of stress echocardiography (SE). However, widespread acceptance of 3D-SE, based on real-time 3D echocardiography, is hampered in part by lack of efficient, accurate, and objective analysis tools.We propose novel algorithms for interactive visualization, registration (alignment), and quantitative analysis of prestress and poststress real-time 3D echocardiography to facilitate an objective diagnosis. In a preliminary evaluation, two experts independently performed wall-motion analysis in 15 patients with known/suspected coronary artery disease, using the novel quantitative 3D-SE methods.Compared with previously reported values for conventional 2-dimensional SE, improved interexpert agreement (κ = 0.85) was observed for segment-wise classification of normal/abnormal wall motion using the novel 3D-SE methods. Overall, 6 of 6 patients with abnormal myocardial segments were correctly identified by both experts with 3D-SE, compared with 4 of 6 with conventional 2-dimensional SE.Initial results are promising and indicate the feasibility and potential of our proposed quantitative 3D-SE methodologies for improving diagnosis of wall-motion abnormalities.

Relevance of tissue Doppler in the quantification of stress echocardiography for the detection of myocardial ischemia in clinical practice

In the present article we review the main published data on the application of Tissue Doppler Imaging (TDI) to stress echocardiography for the detection of myocardial ischemia. TDI has been applied to stress echocardiography in order to overcome the limitations of visual analysis for myocardial ischemia. The introduction of a new technology for clinical routine use should pass through the different phases of scientific assessment from feasibility studies to large multicenter studies, from efficacy to effectiveness studies. Nonetheless the pro-technology bias plays a major role in medicine and expensive and sophisticated techniques are accepted before their real usefulness and incremental value to the available ones is assessed. Apparently, TDI is not exempted by this approach : its applications are not substantiated by strong and sound results. Nonetheless, conventional stress echocardiography for myocardial ischemia detection is heavily criticized on the basis of its subjectivity. Stress echocardiography has a long lasting history and the evidence collected over 20 years positioned it as an established tool for the detection and prognostication of coronary artery disease. The quantitative assessment of myocardial ischemia remains a scientific challenge and a clinical goal but time has not come for these newer ultrasonographic techniques which should be restricted to research laboratories.

Ex vivo 31P magnetic resonance spectroscopy (MRS) of heart grafts provides metabolic markers of early dysfunction in operating room

SPECT within 48 h of a routine heart catheterization. Segmental perfusion (18 segment model, visual grading) with MCE were assessed in real time before and at peak stress using power pulse inversion technique with low mechanical index (0.12) after continuous infusion of SonoVue (Bracco-Byk Gulden, Konstanz, Germany). Data were compared to sestamibi SPECT perfusion imaging and angiography/IVUS as “goldstandard”. Results: Perfusion by MCE predicted significant CAV defined by heart catheterization with a sensitivity of 86%, specificity of 89%, positive (PPV) and negative predictive value (NPV) of 75% and 94%, respectively. Sestamibi SPECT revealed a comparable diagnostic value (sensitivity 86%, specificity 94%, PPV 86%, NPV 94%). Comparison between both perfusion techniques showed a sensitivity of 71%, specificity 83%, PPV 62%, NPV 88%. Conclusion: Real time MCE using power pulse inversion technique correlates well with angiographic/IVUS and SPECT results and is a promising addition to conventional stress echocardiography/-SPECT for the noninvasive detection of significant CAV which might allow a reduction of the routine catheterization surveillance.

Improved detection of inferobasal ischemia during dobutamine echocardiography with doppler tissue imaging

Objectives The purpose of this study was quantitative evaluation of the inferobasal segment during dobutamine stress echocardiography using Doppler tissue imaging (DTI). Background Overdiagnosis of myocardial ischemia during dobutamine echocardiography is a common problem. DTI may permit more accurate quantitative diagnosis of ischemia. Methods A total of 50 patients with normal contraction of the inferobasal segment at rest were referred for dobutamine stress echocardiography. All underwent coronary angiography. Systolic and diastolic myocardial velocities were measured from apical 2-chamber view at rest and at the peak of dobutamine infusion. Results Stenosis of the right coronary artery ≥ 70% was detected in 11 patients. Conventional stress echocardiography was falsely positive in 10.3% and falsely negative in 27.3%. When DTI was combined with conventional stress echocardiography, sensitivity and specificity was 81.8% and 97.4%, respectively. Conclusion DTI may enhance the diagnosis of inferior ischemia during dobutamine echocardiography and can be added to conventional imaging in the treatment of these patients.

Real-time assessment of myocardial perfusion and wall motion during bicycle and treadmill exercise echocardiography: comparison with single photon emission computed tomography

OBJECTIVESWe sought to determine the feasibility and accuracy of real-time imaging of myocardial contrast echocardiography (MCE) in detecting myocardial perfusion defects during exercise echocardiography compared with radionuclide tomography.BACKGROUNDUltrasound imaging at a low mechanical index and frame rate (10 to 20 Hz) after intravenous injections of perfluorocarbon containing microbubbles has the potential to evaluate myocardial perfusion and wall motion (WM) simultaneously and in real time.METHODSOne hundred consecutive patients with intermediate-to-high probability of coronary artery disease underwent treadmill (n = 50) or supine bicycle (n = 50) exercise echocardiography. Segmental perfusion with MCE and WM were assessed in real time before and at peak exercise using low mechanical index (0.3) and frame rates of 10 to 20 Hz after 0.3 ml bolus injections of intravenous Optison (Mallinckrodt Inc., San Diego, California). All patients had a dual isotope (rest thallium-201, stress sestamibi) study performed during the same exercise session, and 44 patients had subsequent quantitative coronary angiography.RESULTSIn the 100 patients, agreement between MCE and single photon emission computed tomography (SPECT) was 76%, while it was 88% between MCE and WM assessment. Compared with quantitative angiography, sensitivity of MCE, SPECT and WM was comparable (75%), with a specificity ranging from 81% to 100%. The combination of MCE and WM had the best balance between sensitivity and specificity (86% and 88%, respectively) with the highest accuracy (86%).CONCLUSIONSThe real-time assessment of myocardial perfusion during exercise stress echocardiography can be achieved with imaging at low mechanical index and frame rates. The combination of WM and MCE correlates well with SPECT and is a promising important addition to conventional stress echocardiography.

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 ≤ 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.

906-64 Doppler Tissue Imaging of Left Ventricular Myocardium — Initial Results During Pharmacologic Stress

The new technique of Doppler tissue imaging (DTI) theoretically has the potential to quantify regional myocardial function. To determine the pattern of normal and ischemic LV contraction and relaxation during pharmacologic stress we studied DTI during a Dobutamin stress test (incremental steps from 5 up to 40 mcg/kg/min per 5’) in 18 patients with suspected ischemic heart disease using coronary angiography (CA) and conventional stress echocardiography (SE) for reference. We used a conventional ultrasound equipment (Acuson 128 XP) with software modifications which allowed also the display of myocardial regional velocities by colour Doppler (CD) and by the pulsed Doppler mode. Velocity patterns were analyzed in representative regions for each vascular bed as for peak velocities of contraction (V c ) and relaxation (V R ) and were compared to the echocardiographic score index in a 14 segment model. DTI images in CD and pulsed wave Doppler could be obtained in all patients. The analysis of 2-dimensional CD images gave similar morphological regional information as SE. Analysis, however, proved difficult in the presence of high heart rates due to low frame rates. In the 7 patients without coronary artery disease, there was a significant increase of V C (9.3 ± 4.1 to 13.1 ± 5.3 cm/s) and V R (-10.4 ± 2.6 to -148 ± 4.2 cm/s) during peak stress (p &lt; 0.01). In infarcted beds, V c and V R were low both before and during peak stress. In regions supplied by an artery with &lt; 50% stenosis, V R more than V c decreased during peak stress. Sensitivity for the diagnosis of coronary artery disease was 81% using SE and 92% using DTI. DTI provides quantification of regional LV contraction and relaxation and thus augments ultrasound stress studies.