Stress echocardiography

Two-dimensional speckle tracking echocardiography in goats: repeatability, variability, and validation of the technique using an exercise test and an experimentally induced acute ischemic cardiomyopathy

Background

Two-dimensional speckle tracking (2DST) technique has been validated in numerous animal species, but neither studies of repeatability nor measurements after exercise or in animals with cardiac disease have been reported in goats. Goats are an attractive candidate for animal models in human cardiology because they are easy to handle and have a body and heart size comparable to that of humans. Therefore, the aim of this study was to validate this technique in goats for further clinical and experimental applications in this species.

Results

This study was divided into several steps. First, a standardized echocardiographic protocol was performed and 5 cineloops of a right parasternal short-axis view at papillary muscles level were recorded three times at one-day intervals in ten healthy adult unsedated Saanen goats to test repeatability and variability of 2DST measurements. Then, the same measurements were performed immediately before and after a standardized exercise on treadmill in seven of the goats, and at 24 h after induction of an experimental ischemic cardiomyopathy in five of the goats, to test the reliability of the technique to assess physiological and pathological changes. Average and regional measurements of radial and circumferential strain and strain rate, radial displacement, rotation and rotation rate were obtained. Comparisons were performed using two-way ANOVA (p < 0.05). Caprine 2DST average measurements have demonstrated a good repeatability with a low to moderate variability for all measurements except for the diastolic peaks of the circumferential strain rate, radial strain rate and rotation rate. Segmental 2DST measurements were less repeatable than average measurements. Time effect of two-way ANOVA was significant for anteroseptal segment diastolic peaks measurements, rotation and rotation rate measurements. Overall variability of segmental measurements was moderate or high. Segmental and average peak values obtained after exercise and after myocardial ischemia were significantly different than curves obtained at baseline.

Conclusions

The results of this study are consistent with those previously described in other animal species and humans. 2DST echocardiography is a valid technique to evaluate physiological and pathological changes in myocardial function in goats, despite the technical limitations observed in this species.

Quantitative detection of myocardial ischaemia by stress echocardiography; a comparison with SPECT

Aims

Real-time perfusion (RTP) adenosine stress echocardiography (ASE) can be used to visually evaluate myocardial ischaemia. The RTP power modulation technique angio-mode (AM), provides images for off-line perfusion quantification using Qontrast^® software, generating values of peak signal intensity (A), myocardial blood flow velocity (β) and myocardial blood flow (Axβ). By comparing rest and stress values, their respective reserve values (A-r, β-r, Axβ-r) are generated. We evaluated myocardial ischaemia by RTP-ASE Qontrast^® quantification, compared to visual perfusion evaluation with ^99mTc-tetrofosmin single-photon emission computed tomography (SPECT).

Methods and Results

Patients admitted to SPECT underwent RTP-ASE (SONOS 5500) using AM during Sonovue^® infusion, before and throughout adenosine stress, also used for SPECT. Visual myocardial perfusion and wall motion analysis, and Qontrast^® quantification, were blindly compared to one another and to SPECT, at different time points off-line.

We analyzed 201 coronary territories (left anterior descendent [LAD], left circumflex [LCx] and right coronary [RCA] artery territories) in 67 patients. SPECT showed ischaemia in 18 patients and 19 territories. Receiver operator characteristics and kappa values showed significant agreement with SPECT only for β-r and Axβ-r in all segments: area under the curve 0.678 and 0.665; P < 0.001 and < 0.01, respectively. The closest agreements were seen in the LAD territory: kappa 0.442 for both β-r and Axβ-r; P < 0.01. Visual evaluation of ischaemia showed good agreement with SPECT: accuracy 93%; kappa 0.67; P < 0.001; without non-interpretable territories.

Conclusion

In this agreement study with SPECT, RTP-ASE Qontrast^® quantification of myocardial ischaemia was less accurate and less feasible than visual evaluation and needs further development to be clinically useful.

Head to head comparisons of two modalities of perfusion adenosine stress echocardiography with simultaneous SPECT

BACKGROUND

Real-time perfusion (RTP) contrast echocardiography can be used during adenosine stress echocardiography (ASE) to evaluate myocardial ischemia. We compared two different types of RTP power modulation techniques, angiomode (AM) and high-resolution grayscale (HR), with 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) for the detection of myocardial ischemia.

METHODS

Patients with known or suspected coronary artery disease (CAD), admitted to SPECT, were prospectively invited to participate. Patients underwent RTP imaging (SONOS 5500) using AM and HR during Sonovue(R) infusion, before and throughout the adenosine stress, also used for SPECT. Analysis of myocardial perfusion and wall motion by RTP-ASE were done for AM and HR at different time points, blinded to one another and to SPECT. Each segment was attributed to one of the three main coronary vessel areas of interest.

RESULTS

In 50 patients, 150 coronary areas were analyzed by SPECT and RTP-ASE AM and HR. SPECT showed evidence of ischemia in 13 out of 50 patients. There was no significant difference between AM and HR in detecting ischemia (p = 0.08). The agreement for AM and HR, compared to SPECT, was 93% and 96%, with Kappa values of 0.67 and 0.75, respectively (p < 0.001).

CONCLUSION

There was no significant difference between AM and HR in correctly detecting myocardial ischemia as judged by SPECT. This suggests that different types of RTP modalities give comparable data during RTP-ASE in patients with known or suspected CAD.

Baseline plasma N-terminal pro-B-type natriuretic peptide is associated with the extent of stress-induced myocardial ischemia during dobutamine stress echocardiography

OBJECTIVE

To determine the relationship between baseline plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and the presence and extent of myocardial ischemia during dobutamine stress echocardiography (DSE).

METHODS

NT-proBNP was measured in 170 consecutive patients prior to DSE. Rest wall motion abnormalities (RWMAs) and new wall motion abnormalities (NWMAs) were scored using a 5-point, 17-segment model. Kruskal-Wallis tests were applied to study differences in NT-proBNP levels between patients with normal DSE, RWMAs but no NWMAs, and NWMAs, and (in patients with NWMAs) between those with 1-2, 3-4 and >4 ischemic segments. Univariate and multivariate regression analyses were used to determine the value of NT-proBNP in predicting NWMAs.

RESULTS

The median NT-proBNP level was 110 ng/l (interquartile range: 42-389 ng/l). Median NT-proBNP was 59, 321 and 440 ng/l in patients with normal DSE, with RWMAs but no NWMAs, and with NWMAs, respectively (P<0001). Among patients with NWMAs, median NT-proBNP was associated with the number of ischemic segments: 364, 710 and 2376 ng/l in patients with 1-2, 3-4 and >4 ischemic segments, respectively (P<0.001). Elevated NT-proBNP levels were significantly associated with NWMAs (odds ratio per 100 ng/l increase: 1.14, 95% confidence interval: 1.1-1.2) in a multivariate analysis of clinical baseline variables and RWMAs.

CONCLUSION

Elevated baseline levels of NT-proBNP are associated with the presence and extent of myocardial ischemia during DSE, independent of the presence of RWMAs.

The long prognostic value of wall motion abnormalities during the recovery phase of dobutamine stress echocardiography after receiving acute beta-blockade

OBJECTIVE

To assess the prognostic value of wall motion abnormalities during the recovery phase of dobutamine stress echocardiography in addition to wall motion abnormalities at peak stress.

METHODS

Wall motion abnormalities were assessed at peak and during recovery phase of dobutamine stress echocardiography in 187 consecutive patients, who were followed for occurrence of cardiac events.

RESULTS

During follow-up (mean 36+/-28 months), 19 patients (10%) died from cardiac causes, 34 (18%) patients suffered nonfatal myocardial infarction, and 77 (41%) patients underwent late revascularization. Univariable predictors of cardiac events by Cox regression analysis were age (hazard ratio: 1.01; confidence interval: 1.00-1.03), dyslipidemia (hazard ratio: 1.41; confidence interval: 1.02-1.95), rest wall motion abnormalities (hazard ratio: 1.37; confidence interval: 1.14-1.64), new wall motion abnormalities (hazard ratio: 1.18; confidence interval: 0.95-1.45) at peak and new wall motion abnormalities (hazard ratio: 1.33; confidence interval: 1.11-1.59) at recovery phase of dobutamine stress echocardiography. The best multivariable model to predict cardiac events included new wall motion abnormality (hazard ratio: 5.34; confidence interval: 1.71-16.59) at recovery phase of dobutamine stress echocardiography, after controlling for clinical and peak dobutamine stress echocardiography data.

CONCLUSIONS

Myocardial ischemia at recovery phase of dobutamine stress echocardiography is an independent predictor of cardiac events and has an incremental value when added to ischemia at peak.

Myocardial viability estimation during the recovery phase of stress echocardiography after acute beta-blocker administration

BACKGROUND

Myocardial viability assessment in severely dysfunctional segments by dobutamine stress echocardiography (DSE) is less sensitive than nuclear scanning.

AIM

To assess the additional value of using the recovery phase of DSE after acute beta-blocker administration for identifying viable myocardium.

METHODS

The study included 49 consecutive patients with ejection fraction (LVEF)<or=35%. All patients underwent DSE evaluation at low-high dose and during recovery phase, and dual-isotope single photon emission tomography (DISA-SPECT) evaluation for viability of severely dysfunctional segments. Patients with >or=4 viable segments were considered viable. Coronary revascularization followed within 3 months in all patients. Radionuclide evaluation of LVEF was performed before and 12 months after revascularization.

RESULTS

Viability with DISA-SPECT was detected in 463 (59%) segments, while 154 (19.7%) segments presented as scar. The number of viable segments increased from 415 (53%) at DSE to 463 (59%) at DSE and recovery, and the number of viable patients increased from 43 to 49 respectively. LVEF improved by >or=5% in 27 patients. Multivariate regression analysis showed that, DSE with recovery phase was the only independent predictor of >or=5% LVEF improvement after revascularization (OR 14.6, CI 1.4-133.7).

CONCLUSION

In this study, we demonstrate that the recovery phase of DSE has an increased sensitivity for viability estimation compared to low-high dose DSE.

Enhanced sensitivity of dobutamine stress echocardiography by observing wall motion abnormalities during the recovery phase after acute beta-blocker administration

Dobutamine stress echocardiography (DSE) has a modest sensitivity for detecting single-vessel coronary artery disease (CAD). This study assessed the additional diagnostic value of new or worsening wall motion abnormalities during recovery after acute administration of beta blockers. The study population consisted of 200 patients (mean 59 +/- 11 years of age, 144 men), who underwent DSE. Images were acquired at rest, low dose, peak dose, and during recovery. Patients received intravenous metoprolol (1 to 5 mg/min). The dose was adjusted to achieve a recovery heart rate within a 10% range of heart rate at rest. Coronary angiography was performed within 2 months. Inducible new wall motion abnormalities were observed in 168 patients (84%) at peak stress. An additional 14 patients (7%) developed new or worsening wall motion abnormalities during recovery. CAD was detected in 182 patients (86 had single-vessel CAD). Sensitivity, specificity, and accuracy of DSE were 88%, 65%, and 73% at peak stress and 97%, 65%, and 74% during recovery. Sensitivity was particularly higher during recovery than during peak stress in patients with single-vessel CAD (98% vs 81%, p <0.001). In conclusion, assessment of wall motion abnormalities during the recovery phase after acute beta blockade improves sensitivity of DSE, particularly in patients with single-vessel CAD.

Noninvasive assessment of coronary artery disease in diabetic patients: The role of stress echocardiography

Diabetes mellitus is a frequently occurring disease, and its prognosis is essentially related to cardiac complications. Some have suggested that these patients should be considered as coronary artery disease (CAD)-equivalent and treated aggressively, accordingly. In addition, CAD in diabetes patients at the time of diagnosis is often more advanced, and is frequently associated with more extensive disease, a greater incidence of left ventricular dysfunction and higher rates of cardiac events. Unfortunately, the standard exercise treadmill stress test has important limitations, with a poor sensitivity for CAD detection if the patient has limited exercise capacity, which is the case for more than one-half of the diabetic patients in some series. The detection of regional wall motion abnormality with echocardiography permits the identification of the coronary territory involved. It can be used for CAD diagnosis, evaluation of myocardial viability, risk stratification following a myocardial infarction and assessment of preoperative risk before noncardiac surgery. The risk of CAD in patients with diabetes mellitus is reviewed, and the role of noninvasive testing with stress echocardiography in the diagnosis and risk stratification of these patients is discussed.

Real-time perfusion adenosine stress echocardiography versus myocardial perfusion adenosine scintigraphy for the detection of myocardial ischaemia in patients with stable coronary artery disease

BACKGROUND

Real-time perfusion (RTP) contrast echocardiography using low mechanical index power modulation technique allows for simultaneous myocardial perfusion and wall motion analysis. RTP-adenosine stress echocardiography (ASE) could be an alternative to dobutamine-atropine stress echocardiography; more tolerable for the patients and possibly similarly accurate. We aimed to evaluate RTP-ASE for the detection of myocardial ischaemia, compared to 99mTc-sestamibi single-photon emission computed tomography (SPECT).

METHODS

Patients with suspected coronary artery disease, admitted to SPECT evaluation, were prospectively invited to participate. Patients underwent RTP imaging (SONOS 5500) using infusion of Sonovue (Bracco, Milano, Italy) before and during ASE. Two separate readers performed off-line analysis of myocardial perfusion and wall motion by RTP-ASE. A perfusion defect was the principal marker of ischaemia. Wall motion assessment was used to evaluate ischaemia in segments with perfusion artefacts. Each segment was attributed to one of the three main coronary vessel areas of interest: the left anterior descending (LAD); the left circumflex (LCx) and the right posterior descending (RPD). Normal SPECT at stress was judged normal at rest.

RESULTS

In 33 patients, 99 coronary territories were analysed by SPECT and RTP-ASE. SPECT showed evidence of ischaemia in 9 of 33 patients. For the detection of ischaemia, the overall level of agreement between RTP-ASE and SPECT was 92% in all segments. The level of agreement was 88% in LAD, 97% in LCx and 91% in RPD segments.

CONCLUSION

Real-time perfusion-adenosine stress echocardiography using power modulation could be an accurate and feasible tool for evaluation of ischaemia in patients with suspected coronary artery disease. The results from this study need confirmation by a study of a larger patient sample.

Dobutamine stress echocardiography in healthy adult male rats

BACKGROUND

Dobutamine stress echocardiography is used to investigate a wide variety of heart diseases in humans. Dobutamine stress echocardiography has also been used in animal models of heart disease despite the facts that the normal response of healthy rat hearts to this type of pharmacological stress testing is unknown. This study was performed to assess this normal response.

METHODS

15 normal adult male Wistar rats were evaluated. Increasing doses of dobutamine were infused intravenously under continuous imaging of the heart by a 12 MHz ultrasound probe.

RESULTS

Dobutamine stress echocardiography reduced gradually LV diastolic and systolic dimensions. Ejection fraction increased by a mean of +24% vs. baseline. Heart rate increased progressively without reaching a plateau. Changes in LV dimensions and ejection fraction reached a plateau after a mean of 4 minutes at a constant infusion rate.

CONCLUSION

DSE can be easily performed in rats. The normal response is an increase in heart rate and ejection fraction and a decrease in LV dimensions. A plateau in echocardiographic measurements is obtained after 4 minutes of a constant infusion rate in most animals.