Use of contrast for image enhancement during stress echocardiography is cost-effective and reduces additional diagnostic testing

Cardiac functional imaging

During the last 20 years, cardiac imaging has drastically evolved. Positron emission tomography (PET), fast three-dimensional (3D) imaging with the latest generations of echocardiography & multi-detector computed tomography (CT), stress perfusion assessed by magnetic resonance imaging (MRI), blood flow analysis using four-dimensional (4D) flow MRI, all these techniques offer new trends for optimal noninvasive functional cardiac imaging. Dynamic functional imaging is obtained by acquiring images of the heart at different phases of the cardiac cycle, allowing assessment of cardiac motion, function, and perfusion. Between CT and Cardiac MRI (CMR), CMR has the best temporal resolution, which is suitable for functional imaging while cardiac CT provides higher spatial resolution with isotropic data that have an identical resolution in the three dimensions of the space. The latest generations of CT scanners enable whole heart assessment in one beat, offering also an acceptable temporal resolution with the possibility to display the images in a dynamic mode. Another rapidly growing technique using functional and molecular imaging for the assessment of biological and metabolic pathways is the PET using radio-labeled tracers. Meanwhile, the oldest cardiac imaging tool with doppler ultrasound technology has never stopped evolving. Echocardiography today performs 3D imaging, stress perfusion, and myocardial strain assessment, with high temporal resolution. It still is the first line and more accessible exam for the patient. These different modalities are complementary and may be even combined into PET-CT or PET-MRI. The ability to combine the functional/molecular data with anatomical images may implement a new dimension to our diagnostic tools.

Left Ventricular Apical Aneurysms in Hypertrophic Cardiomyopathy: Equivalent Detection by Magnetic Resonance Imaging and Contrast Echocardiography

BACKGROUND

Left ventricular (LV) apical aneurysm is a unique morphological entity and novel adverse risk marker existing within the broad phenotypic spectrum of hypertrophic cardiomyopathy (HCM). Its true prevalence in the HCM population is likely underestimated because of inherent limitations of conventional noncontrast echocardiography. The authors hypothesized that contrast echocardiography is a reliable imaging technique compared with cardiovascular magnetic resonance (CMR) for the detection of apical aneurysms. The aim of this study was to assess the effectiveness of contrast echocardiography in the detection of LV apical aneurysms in patients with HCM in comparison with the gold standard, CMR.

METHODS

One hundred twelve patients with HCM identified from an institutional clinical database, who underwent echocardiographic and CMR examinations within 12 months and had LV apical aneurysms identified on either or both imaging modalities, were retrospectively analyzed. Discordant cases were reviewed by an expert panel, and a consensus was reached regarding the presence or absence of an apical aneurysm. The reason for any discrepancy was recorded.

RESULTS

The mean age of the patients was 59 ± 13 years, and 73% were men. Sixty-four (57%) underwent contrast echocardiography. The median interval between echocardiography and CMR was 118 days (interquartile range, 61-237 days). Thirty-nine patients (35%) had discordance between echocardiographic and CMR findings, of whom 20 had aneurysms reported on echocardiography but not CMR and 19 vice versa. Upon reanalysis by the expert panel, aneurysms were initially missed on CMR in 16 patients (80%), largely because of interpretation error secondary to small aneurysms, with a mean aneurysm size of 0.82 ± 0.38 cm in these cases. Before secondary review by the expert panel, contrast echocardiography had sensitivity of 97% compared with 85% for CMR (P = .0198) and 64% for noncontrast echocardiography (P = .0001). After secondary review, contrast echocardiography had sensitivity of 98% compared with 67% for noncontrast echocardiography (P = .0001) and 97% for CMR (P = 1.00).

CONCLUSIONS

Contrast echocardiography has high sensitivity for detecting LV apical aneurysms and should be used routinely in the evaluation and risk stratification of patients with HCM.

Real-world performance and accuracy of stress echocardiography: the EVAREST observational multi-centre study

Aims

Stress echocardiography is widely used to identify obstructive coronary artery disease (CAD). High accuracy is reported in expert hands but is dependent on operator training and image quality. The EVAREST study provides UK-wide data to evaluate real-world performance and accuracy of stress echocardiography.

Methods and results

Participants undergoing stress echocardiography for CAD were recruited from 31 hospitals. Participants were followed up through health records which underwent expert adjudication. Cardiac outcome was defined as anatomically or functionally significant stenosis on angiography, revascularization, medical management of ischaemia, acute coronary syndrome, or cardiac-related death within 6 months. A total of 5131 patients (55% male) participated with a median age of 65 years (interquartile range 57–74). 72.9% of studies used dobutamine and 68.5% were contrast studies. Inducible ischaemia was present in 19.3% of scans. Sensitivity and specificity for prediction of a cardiac outcome were 95.4% and 96.0%, respectively, with an accuracy of 95.9%. Sub-group analysis revealed high levels of predictive accuracy across a wide range of patient and protocol sub-groups, with the presence of a resting regional wall motion abnormalitiy significantly reducing the performance of both dobutamine (P < 0.01) and exercise (P < 0.05) stress echocardiography. Overall accuracy remained consistently high across all participating hospitals.

Conclusion

Stress echocardiography has high accuracy across UK-based hospitals and thus indicates stress echocardiography is being delivered effectively in real-world practice, reinforcing its role as a first-line investigation in the assessment of patients with stable chest pain.

A review of the safety and clinical utility of contrast echocardiography

There are limitations to the sensitivity and specificity of conventional two-dimensional echocardiograms in making an accurate diagnosis in certain patient populations. This led to the development of specific contrast-enhancing agents with the following characteristics: small enough to cross the pulmonary capillary bed, remain stable throughout the length of the procedure, do not dissolve in blood, and rapidly cleared from the body with low toxicity. Unfortunately, the use of contrast echocardiography has not taken off as expected. The low take-up rate among clinicians can largely be attributed to the black box warning by the United States Food and Drug Administration in 2007, after the coincidental occurrence of four patient deaths and about 190 severe cardiopulmonary reactions shortly after contrast agent administration. In this article, we address the clinical safety of contrast agents, share our institution's experience in using it and elaborate on the clinical indications of contrast echocardiography.

Early ischemia identification employing 2D speckle tracking selective layers analysis during dobutamine stress echocardiography

PURPOSE

Two-dimensional (2D) strain derived from speckle tracking proved to be feasible and accurate in the quantitative evaluation of myocardial ischemia during stress echocardiography. We compared the accuracy in detecting myocardial ischemia of the transmural segmental analysis with an endocardial specific evaluation in 20 patients undergoing dobutamine stress echocardiography (DSE) and coronary angiography.

METHODS

Peak systolic global strain (G-ε) and at the subendocardial level (Endo-ε) were measured off-line at rest, a low dose, and peak stress; then, we compared the results with wall-motion analysis and significant coronary artery disease (CAD > 70% diameter stenosis). Endocardial strain variation from basal to low and peak dose was computed both for global or subendocardial analysis. The utilization of the ROC curve allowed us to derive optimal cutoffs, sensibility and specificity for ischemic segments.

RESULTS

The subendocardial analysis at high dose showed to be able to increase significantly the accuracy of the test to detect the ischemic segments (sens 90.2% vs 85.4%; spec 93.1% vs 92.2%). Moreover, at the low dose, the subendocardial analysis showed to be able to increase significantly, mostly the specificity of the test (sens 69.6% vs 68.3%; spec 92.2% vs 86.2%). Notably, the strain subendocardial analysis at low dose showed to reach a high specificity, similar to the peak dose transmural analysis.

CONCLUSIONS

Measurement of subendocardial strain during DSE is feasible and can increase the accuracy of the test. Moreover, the subendocardial strain during DSE can reach a high specificity, even limiting the test at a low dose infusion.

Shenzhu Guanxin Recipe Granules () for Improving Exercise Tolerance in Patients with Stable Angina (SERIES Trial): A Protocol of Multicenter, Randomized, Double-Blind, Placebo Parallel Controlled Clinical Trial

BACKGROUND

Many patients with chronic angina experience anginal episodes despite successful recanalization, antianginal and antiischemic medications. Empirical observations suggested that Shenzhu Guanxin Recipe Granules (, SGR), a Chinese herbal compound, exerted potential impacts on increased treadmill exercise performance and angina relieve. However, there has been no systematic study to clarify the impact of SGR on exercise tolerance in patients with stable angina. The SERIES (ShEnzhu guanxin Recipe for Improving Exercise tolerance in patients with Stable angina) trial is designed to determine the effects of SGR on exercise duration, electrocardiographic (ECG) evidence of myocardial ischemia, and incidence of major adverse cardiac events (MACE) in stable anginal patients.

METHODS

A total of 184 eligible patients with stable angina will be randomly assigned to receive placebo or SGR (10 g/day for 12 weeks) in a 1:1 ratio. The primary outcome will be the change from baseline in total exercise tolerance duration, time to onset of angina and ECG ischemia during exercise treadmill testing performed over a 12-week study period. The secondary outcome will include ECG measures, the occurrence and composite of MACE and the Seattle Angina Questionnaire score. Moreover, the coronary microcirculation will be evaluated to explore the possible effects in response to treatment of SGR. After the procedure, all participants will be followed up by interview at 3 and 6 months, enquiring about any cardiac events, hospitalizations, cardiac functional level and medication usage. Additionally, the occurrence of adverse events will be evaluated at each follow-up.

DISCUSSION

This study may provide novel evidence on the efficacy of SGR in improving exercise tolerance and potentially reducing clinical adverse events. (Trial registration No. ChiCTR-TRC-14004504).

Clinical practice of contrast echocardiography: recommendation by the European Association of Cardiovascular Imaging (EACVI) 2017

Contrast echocardiography is widely used in cardiology. It is applied to improve image quality, reader confidence and reproducibility both for assessing left ventricular (LV) structure and function at rest and for assessing global and regional function in stress echocardiography. The use of contrast in echocardiography has now extended beyond cardiac structure and function assessment to evaluation of perfusion both of the myocardium and of the intracardiac structures. Safety of contrast agents have now been addressed in large patient population and these studies clearly established its excellent safety profile. This document, based on clinical trials, randomized and multicentre studies and published clinical experience, has established clear recommendations for the use of contrast in various clinical conditions with evidence-based protocols.

Contrast-Enhanced Stress Echocardiography and Myocardial Perfusion Imaging in Patients Hospitalized With Chest Pain: A Randomized Study

Ultrasound contrast-enhanced stress echocardiography improves endocardial visualization, but diagnostic test rates versus stress myocardial perfusion imaging (MPI) have not been studied. A prospective randomized trial was performed between April 2012 and October 2014 at a single-center, safety net hospital. Hospitalized patients referred for noninvasive stress imaging were randomized 1:1 to stress echocardiography or stress MPI. The primary outcome was diagnostic test rate defined as interpretable images and achievement of >85% of age-predicted maximal heart rate (for dobutamine and exercise). Rates were assessed among those completing testing and then based solely on image interpretability. Charges and length of stay were secondary outcomes. A total of 240 patients were randomized, and 229 completed testing. Diagnostic test rates were similar for stress echocardiography versus MPI {89.4% [95% confidence interval (CI), 82.2-94.4] vs. 94.8% [95% CI, 89.1-98.1], P = 0.13} and did not differ with multivariable adjustment. Modalities requiring a diagnostic heart rate criteria were more frequently ordered with stress echocardiography (100% vs. 26%; P < 0.001). Therefore, an imaging-based analysis without the 12 individuals who failed to achieve target heart rate (n = 217) was evaluated with diagnostic test rates of 100% versus 94.8% (95% CI, 89.1%-98.1%; P = 0.03) for stress echocardiography and MPI, respectively. Median length of stay did not differ. Median (interquartile range) test-related charges were lower with stress echocardiography: $2,424 ($2400-$2508) versus $3619 ($3584-$3728), P < 0.0001. Overall, tests were positive for ischemia in 8% of patients. In conclusion, contrast-enhanced stress echocardiography provides comparable diagnostic test rates to MPI with lower associated charges.

Contrast echocardiography in daily clinical practice

Ultrasound contrast agents have unique acoustic properties that enable them to enhance the cardiac blood flow and thus are used broadly in modern echocardiography laboratories for salvage of nondiagnostic studies, improving accuracy and reducing variability even in the presence of adequate image quality. Contrast echocardiography is also used as an adjunctive technique when unenhanced echocardiography falls short in the differentiation of cardiac structural abnormalities such as cardiac masses. Ultrasound contrast agents are pure intravascular tracers. Development of innovative ultrasound imaging techniques has led to myocardial perfusion imaging with contrast echocardiography. Although currently an off-label indication, it has been shown that perfusion imaging with contrast echocardiography adds incremental value to stress echocardiography in the detection of coronary artery disease. Moreover, it can be used for assessment of myocardial viability. In this paper we briefly discuss the basics of contrast echocardiography and its use in daily clinical practice.

Safety With Echocardiographic Contrast Agents

In October 2007, the Food and Drug Administration mandated significant revisions to product labeling for the commercially available echocardiographic contrast agents (ECA) Definity and Optison after spontaneous healthcare provider reports of 4 patient deaths and ≈190 severe cardiopulmonary reactions occurring in close temporal relationship to ECA administration. Since then, multiple large ECA safety studies have been published and have included outpatients, hospitalized patients (including the critically ill), patients undergoing stress echocardiography, and patients with pulmonary hypertension. In addition, the Food and Drug Administration has convened 2 Advisory Committee meetings and the product labels for Optison and Definity have been substantially revised with a softening of safety restrictions. In this review, we will address the safety of ECA use in patients with serious cardiopulmonary conditions, patients with intracardiac shunts, and special patient populations including pulmonary hypertension, pediatrics, and pregnancy. In addition, we will discuss the confounding role of pseudocomplication in attribution of adverse events during diagnostic testing, the current status of the ECA Black Box Warning, and recommended safety precautions during ECA administration.

Impact of Contrast Echocardiography on Assessment of Ventricular Function and Clinical Diagnosis in Routine Clinical Echocardiography: Korean Multicenter Study

Background

Fundamental echocardiography has some drawbacks in patients with difficult-to-image echocardiograms. The aim of this study is to evaluate impact of contrast echocardiography (CE) on ventricular function assessment and clinical diagnosis in routine clinical echocardiography.

Methods

Two hundred sixty patients were prospectively enrolled over 3 years in 12 medical centers in Korea. General image quality, the number of distinguishable segments, ability to assess regional wall motion, left ventricular (LV) apex and right ventricle (RV) visualization, LV ejection fraction, changes in diagnostic or treatment plan were documented after echocardiography with and without ultrasound contrast agent.

Results

Poor or uninterpretable general image was 31% before contrast use, and decreased to 2% (p<0.05) after contrast use. The average number of visualized LV segments was 9.53 before contrast use, and increased to 14.46 (p<0.001) after contrast use. The percentage of poor or not seen LV regional wall motion was decreased from 28.4% to 3.5% (p<0.001). The percentage of poor or not seen LV apex and RV was decreased from 49.4% to 2.4% (p<0.001), from 30.5% to 10.5% (p<0.001), respectively. Changes in diagnostic procedure and treatment plan after CE were 30% and 29.6%, respectively.

Conclusion

Compared to fundamental echocardiography, CE impacted LV function assessment and clinical decision making in Korean patients who undergo routine echocardiography.

Myocardial Contrast Agents – Safety Considerations and Clinical Efficacy in Stress Echocardiography

Transthoracic echocardiographic examination is known to be a safe, non-invasive and reproducible method, used in every day clinical practice to obtain important information about cardiac structure and function. Unfortunately, a significant proportion of studies have highlighted the considerable technically difficultly in producing diagnostic images due to a poor acoustic window and more than 33% of patients undergoing stress echocardiography have suboptimal echocardiographic images. All these limitations have led to the use of contrast agents to improve the quality of standard ultrasound examination to provide a better delineation of left ventricle endocardial borders or to obtain information that cannot be achieved by using standard echocardiography, such as assessing myocardial microcirculation and therefore perfusion. This paper sought to review the clinical efficacy and safety of ultrasound contrast agents focusing on stress echocardiography.

A primer on the methods and applications for contrast echocardiography in clinical imaging

Contrast echocardiography is broadly described as a variety of techniques whereby the blood pool on cardiac ultrasound is enhanced with encapsulated gas-filled microbubbles or other acoustically active nano- or microparticles. The development of this technology has occurred primarily in response to the need improve current diagnostic applications of echocardiography such as the need to better define left ventricular cavity volumes, regional wall motion, or the presence or absence of masses and thrombi. A secondary reason for the development of contrast echocardiography has been to expand the capabilities of echocardiography. These new applications include myocardial perfusion imaging for detection of ischemia and viability, perfusion imaging of masses/tumors, and molecular imaging. The ability to fill all of these current and future clinical roles has been predicated on the ability to produce robust contrast signal which, in turn, has relied on technical innovation with regards to the microbubble contrast agents and the ultrasound imaging paradigms. In this review, we will discuss the basics of contrast echocardiography including the composition of microbubble contrast agents, the unique imaging methods used to optimize contrast signal-to-noise ratio, and the clinical applications of contrast echocardiography that have made a clinical impact.

The feasibility and clinical utility of myocardial contrast echocardiography in clinical practice: results from the incorporation of myocardial perfusion assessment into clinical testing with stress echocardiography study

BACKGROUND

This prospective study investigated whether the incorporation of myocardial contrast echocardiography (MCE) into a clinical stress echocardiography service reproduces the benefits of assessing myocardial perfusion proved previously in research studies.

METHODS

MCE was performed during physiologic and pharmacologic clinical stress echocardiographic studies, and the value of myocardial perfusion to the reporting echocardiologists was categorized as of benefit (subclassified as incremental benefit over wall motion [WM] or greater confidence with WM) or of no added benefit. The presence and extent of inducible ischemia by WM and myocardial perfusion were documented and correlated with angiographic results in patients who underwent cardiac catheterization.

RESULTS

In total, 220 patients underwent simultaneous MCE during stress echocardiography by eight different operators. Overall, MCE was of benefit in 193 patients (88%), providing incremental benefit over WM in 25% and greater confidence with WM evaluation in 62%. MCE provided no added benefit in 27 patients (12%). MCE detected significantly more cases of ischemia than WM in the left anterior descending coronary artery territory (65% vs 53%, P = .02) and detected a greater ischemic burden than WM on a per patient basis (median, 5 [interquartile range, 3-8] vs 4 [interquartile range, 2-7] segments; P < .001) and across all coronary territories. MCE correctly identified a greater proportion of patients with multivessel disease than WM (76% vs 56%, P = .02) and a greater ischemic burden in patients with multivessel disease (median, 7 [interquartile range, 4-9] vs 5 [interquartile range, 1-8] segments; P < .001).

CONCLUSIONS

This prospective study is the first to demonstrate that the excellent feasibility and diagnostic utility of MCE, which have been documented in the research arena, are reproducible in the clinical arena.

Echocardiography in the era of multimodality cardiovascular imaging

Echocardiography remains the most frequently performed cardiac imaging investigation and is an invaluable tool for detailed and accurate evaluation of cardiac structure and function. Echocardiography, nuclear cardiology, cardiac magnetic resonance imaging, and cardiovascular-computed tomography comprise the subspeciality of cardiovascular imaging, and these techniques are often used together for a multimodality, comprehensive assessment of a number of cardiac diseases. This paper provides the general cardiologist and physician with an overview of state-of-the-art modern echocardiography, summarising established indications as well as highlighting advances in stress echocardiography, three-dimensional echocardiography, deformation imaging, and contrast echocardiography. Strengths and limitations of echocardiography are discussed as well as the growing role of real-time three-dimensional echocardiography in the guidance of structural heart interventions in the cardiac catheter laboratory.

Clinical application and laboratory protocols for performing contrast echocardiography

Technically difficult echocardiographic studies with suboptimal images remain a significant challenge in clinical practice despite advances in imaging technologies over the past decades. Use of microbubble ultrasound contrast for left ventricular opacification and enhancement of endocardial border detection during rest or stress echocardiography has become an essential component of the operation of the modern echocardiography laboratory. Contrast echocardiography has been demonstrated to improve diagnostic accuracy and confidence across a range of indications including quantitative assessment of left ventricular systolic function, wall motion analysis, and left ventricular structural abnormalities. Enhancement of Doppler signals and myocardial contrast echocardiography for perfusion remain off-label uses. Implementation of a contrast protocol is feasible for most laboratories and both physicians and sonographers will require training in contrast specific imaging techniques for optimal use. Previous concerns regarding the safety of contrast agents have since been addressed by more recent data supporting its excellent safety profile and overall cost-effectiveness.

Implementation of echocardiographic contrast agents into clinical practice: a United Kingdom National Health Service Survey on behalf of the British Society of Echocardiography

AIMS

The administration of echocardiographic contrast agents has been shown to improve accuracy and be cost-effective in patients with suboptimal endocardial definition. We sought to investigate the implementation of contrast agents in clinical practice.

METHODS AND RESULTS

An electronic questionnaire was devised to determine the use of contrast ultrasound agents in clinical practice and sent electronically to echocardiography departments at each national health service hospital within the UK. Out of 198, 107 departments responded (54%). Out of 673,121 echocardiograms, 25,834 (3.8%) were performed with contrast. Out of 551 echocardiography machines, 358 (65%) were suitable for contrast use. Of the sonographers, out of 711, 112 (15.8%) could perform i.v. cannulation and 42 (5.9%) could administer contrast independently. The median time for an echocardiographic examination was 30 min (inter-quartile range 30-45 min). Significant predictors of contrast use were the presence of a consultant cardiologist with subspecialty training in echocardiography (odds ratio 8.7, P = 0.004), the presence of a stress echocardiography service (odds ratio 2.3, P = 0.004), and the presence of a physician during the day (odds ratio 3.0, P = 0.04). Reasons for impediment in administering contrast were staff training (34.6%), extra time required for a contrast study (29.9%), and the expense of contrast (18.7%).

CONCLUSION

The use of echocardiographic contrast agents within routine echocardiographic practice in the UK is limited to <4% of all transthoracic echocardiographic studies. Major barriers to the implementation of contrast use are the absence of cardiac imaging specialists directly supervising echocardiography departments and the training of sonographers to independently administer contrast.

Administration of perflutren contrast agents during transthoracic echocardiography is not associated with a significant increase in acute mortality risk

BACKGROUND

Despite the 2008 revision of a previously issued black box warning of the US Food and Drug Administration against the use of perflutren ultrasound contrast agents, the warning still reports fatalities having occurred following their administration. We sought to assess 1-day mortality associated with contrast use across a wide range of clinical settings and co-morbidities.

METHODS

We conducted a retrospective study involving 96,705 transthoracic echocardiograms (TTE) in 63,189 adults at our institution between July 2003 and June 2008. A contrast agent was used in 2,518 TTE during this time. The primary outcome was total mortality within 1 day of TTE.

RESULTS

Death occurred in 10 patients (0.44%) in the contrast group and in 421 patients (0.69%) in the non-contrast group (p = 0.14). In a multivariate model, use of contrast enhancement was not associated with increased mortality (p = 0.67) after adjustment for age, gender, race, patient location, ejection fraction, and the presence of various co-morbidities. Cause of death analysis did not identify any cases where contrast played a likely role.

CONCLUSION

Definity contrast use during TTE was not associated with increased acute mortality risk. Contrast administration during TTE should not be withheld when the additional information obtained could potentially improve patient management.

Quality Assessment in Dobutamine Stress Echocardiography: What are the Clinical Predictors Associated With a Non-Diagnostic Test?

Background

Non-diagnostic dobutamine stress echocardiography (ndDSE, failure to achieve 85% of maximal predicted heart rate (HR) without evidence of inducible ischemia) is an important limitation affecting quality of DSE testing. The objectives of this study were to identify the clinical variables associated with a non-diagnostic Dobutamine Stress Echocardiogram (ndDSE) and further evaluate the patterns of subsequent testing for myocardial ischemia.

Methods

Consecutive DSE’s over a 17 month period (January 2008 to June 2009) were studied. Baseline demographics, medical history, and vital signs were collected. Subsequent testing was determined for up to 6 months after the initial DSE. Univariate and multivariate logistic regression analysis was performed to identify clinical factors associated with ndDSE.

Results

Of 467 total DSE, 314 (67%) were negative for ischemia, 69 (15%) were positive, and 84 (18%) were ndDSE. Of those recommended for further nuclear MPI testing 12 (14%) had an ndDSE compared to 16 (4%) patients with a diagnostic DSE (P = 0.001). Fifty percent of the ndDSE nuclear MPI tests were positive for ischemia. In the univariate analysis, Diabetes Mellitus (DM; P = 0.003), calcium channel antagonist (CCA) use (P = 0.047), Hypertension (HTN; P = 0.06), low baseline HR (P < 0.001), and younger age group (P = 0.02) were predictive of ndDSE. Of these, all except CCA use remained independent predictors of ndDSE in multivariate analysis. A 4 variable model for predicting ndDSE was developed from the multivariate logistic regression displayed in Table 1 (age and baseline HR were categorized and scored 0-2; DM and HTN were scored as 0 (absent) or 1 (present)). Figure 2 demonstrates how risk of ndDSE correlated with a higher score, with each increment having an odds ratio of 2.1 (P < 0.001).

Conclusions

DM, HTN, younger age, and lower baseline HR affect the quality of DSE testing, resulting in non-diagnostic tests. A model combining these factors can identify patients most likely to have this outcome. Identification of this cohort may improve referral patterns and improve the quality of stress testing.

Safety of echocardiographic contrast in hospitalized patients with pulmonary hypertension: a multi-center study

AIMS

Echocardiographic contrast (EC) improves the diagnostic accuracy of suboptimal echocardiograms. In October 2007, the Food and Drug Administration (FDA) placed a black box warning on the label of the perflutren-based agents Definity and Optison, contraindicating their use in patients with pulmonary hypertension (PHT) and unstable cardiopulmonary status, after serious cardiopulmonary reactions occurred in temporal relation to EC administration. In 2008 and 2011, the FDA revised the black box warning allowing their use in this same population. However, limited data exist regarding the safety profile of these agents in patients with PHT.

METHODS AND RESULTS

Consecutive hospitalized patients with PHT who were referred for echocardiographic evaluation, but required the use of EC, were included. All our patients received the EC agent Definity. We evaluated these patients for serious adverse events (respiratory decompensation, hypotension, syncope, convulsions, arrhythmias, anaphylactic reactions, or death) occurring within 24 h of EC administration. The study group included 1513 patients (age 69 ± 14 years, 55% males, BMI 33 ± 9 kg/m(2)), of which 911 (60%) had mild PHT, 515 (34%) had moderate PHT, and 87 (6%) had severe PHT. The mean pulmonary artery systolic pressures (PASP) in the groups with mild, moderate, and severe PHT were 41 ± 4 (range 35-49) mmHg, 55 ± 5 (range 50-69) mmHg, and 78 ± 9 (range 70-122) mmHg, respectively. The incidence of adverse events in all subgroups was rare (0.002%) and they were not attributed to EC because of temporal and clinical considerations.

CONCLUSION

The use of the EC agent Definity is safe in hospitalized patients with PHT.

Meta-analysis of adverse cardiovascular events associated with echocardiographic contrast agents

In October 2007, the Federal Drug Agency issued a black box warning for contrast agents used in patients undergoing echocardiography and restricted their use in patients with acute coronary syndrome, a decompensated heart, and respiratory failure. We performed a systemic review and meta-analysis to study the adverse effects of contrast agents used with respect to myocardial infarction and all-cause mortality. MEDLINE, EMBASE, BIOSIS, and Cochrane databases from inception to October 2009 were searched for studies that reported myocardial infarction and all-cause mortality after the use of contrast agents for echocardiography. A total of 8 studies were included in the present meta-analysis. A random-effect model was used, and between-studies heterogeneity was estimated with I(2). A total of 8 studies reported death as an outcome and only 4 reported myocardial infarction. The incidence of death in the contrast group was 0.34% (726 of 211,162 patients) compared to 0.9% (45,970 of 5,078,666 patients) in the noncontrast group. The pooled odds ratio was 0.57 (95% confidence interval 0.32 to 1.01, p = 0.05). The reported incidence of myocardial infarction in the contrast group was 0.15% (86 of 57,264 patients) compared to 0.2% (92 of 44,503 patients) in the noncontrast group. The pooled odds ratio was 0.85 (95% confidence interval 0.35 to 2.05, p = 0.72). Significant heterogeneity was seen among the studies. In conclusion, the cumulative evidence has suggested that the use of contrast agents for echocardiography is safe and not associated with a greater incidence of myocardial infarction or and mortality.

Initial experience using contrast enhanced real-time three-dimensional exercise stress echocardiography in a low-risk population

Although emerging data support the utility of real-time three-dimensional echocardiography (RT3DE) during dobutamine stress testing, the feasibility of performing contrast enhanced RT3DE during exercise treadmill stress has not been explored. Two-dimensional (2D) and three-dimensional (3D) acquisition were performed in 39 patients at rest and peak exercise. Contrast was used in 29 patients (74%). Reconstruction was performed manually by generating short axis cut planes at the base, mid-ventricle and apex, and automatically by generating 9 short axis slices. Three-dimensional acquisition was feasible during rest and stress regardless of the use of contrast. Time to acquire stress images was reduced using 3D (35.2±17.9 s) as compared to 2D acquisition (51.6±14.7 s; P<0.05). Using a 17-segment model, of all 663 segments, 588 resting (88.6%) and 563 stress segments (84.9%) were adequately visualized using manually reconstructed 3D data, compared with 618 resting (93.2%) and 606 stress segments (91.4%) using 2D data (P rest=0.06; P stress=0.07). We concluded that contrast enhanced RT3DE is feasible during treadmill stress echocardiography.

Echocardiography for the clinician: a practical update

Echocardiography is the mainstay of cardiovascular diagnostics, and is the most performed test for the evaluation of cardiac function. Critical and costly management decisions are based on quantification of left ventricular volumes and ejection fraction. Recent advances in echocardiography, such as microsphere contrast echocardiography for left ventricular opacification and perfusion imaging, three-dimensional transthoracic and trans-oesophageal imaging, strain and tissue Doppler imaging, all contribute to improving accuracy and reproducibility of these important measurements. Such techniques are now routinely available on standard echocardiography equipment in Australian centres for daily use. Hand-carried ultrasound devices have been developed, which are portable, are affordable and offer increased availability of echocardiography to the wider community. Clinicians should be actively encouraged to adopt these technologies to improve the diagnostic quality and reproducability of echocardiography for our patients. This article provides an overview of important recent advances in echocardiographic imaging with an emphasis on their role in clinical practice today.

Pretest score for predicting microbubble contrast agent use in stress echocardiography: a method to increase efficiency in the echo laboratory

Background. In stress echocardiography, contrast agents are used selectively to improve endocardial border definition. Early identification of candidates may facilitate use of these agents in small and medium volume laboratories where resources are limited. Methods. We studied 15232 patients who underwent stress echocardiography. Contrast agent was used if 2 or more ventricular segments were not adequately visualized without contrast. Logistic regression models were used to evaluate the association between individual characteristics and contrast use. An 11-point score was derived from the significant characteristics. Results. Variables associated with microbubble use were age, sex, smoking, presence of multiple risk factors, bodymass index (BMI), referral for dobutamine stress echocardiography, history of coronary artery disease, and abnormal baseline electrocardiogram. All variables except BMI were given a score of 1 if present and 0 if absent; BMI was given a score of 0 to 4 according to its value. An increased score was directly proportional to increased likelihood of contrast use. The score cutoff value to optimize sensitivity and specificity was 5. Conclusions. A pretest score can be computed from information available before imaging. It may facilitate contrast agent use through early identification of patients who are likely to benefit from improved endocardial border definition.

Safety of contrast in stress echocardiography in stable patients and in patients with suspected acute coronary syndrome but negative 12-hour troponin

Limited studies are available demonstrating the safety of contrast agents in patients undergoing stress echocardiography and none in patients with suspected acute coronary syndrome (ACS). Therefore, we sought to assess the safety profile of contrast agents in patients with stable chest pain and in those with suspected ACS (nondiagnostic electrocardiogram and negative initial 12-hour cardiac troponin test results). During a 4-year period, 3,704 patients underwent stress echocardiography (exercise or dobutamine), of whom, 929 (25%) had suspected ACS. Contrast agents (SonoVue 46%, Luminity 54%) were used in 1,150 patients (31%). No patients died with or without contrast administration. No nonfatal acute myocardial infarction occurred in patients administered contrast agents compared with 3 cases of acute myocardial infarction in the noncontrast group (p = 0.24). Two cases of sustained ventricular tachycardia developed, one in each group (p = 0.98). Compared with those who did not receive contrast, patients in both the stable chest pain and the suspected ACS groups had a greater burden of cardiovascular risk factors. The left ventricular function at rest was significantly worse in the patients who received contrast than in those who did not in the suspected ACS group. Also, a greater ischemic burden was present in those receiving contrast than in those not receiving it in both the stable chest pain and the suspected ACS groups. In conclusion, despite the presence of greater risk features compared with patients undergoing unenhanced stress echocardiography, the administration of ultrasound contrast agents (SonoVue and Luminity) in those with stable chest pain and those with suspected ACS was not associated with excess adverse events.

A randomized cross-over study for evaluation of the effect of image optimization with contrast on the diagnostic accuracy of dobutamine echocardiography in coronary artery disease The OPTIMIZE Trial

OBJECTIVES

The purpose of this study was to evaluate whether the addition of a contrast agent to dobutamine stress echocardiography (DSE) improves its diagnostic accuracy for coronary artery disease (CAD) and to determine the effect of image quality on the diagnostic impact of contrast agent use in this setting.

BACKGROUND

Contrast agents can improve endocardial border definition. To date, however, there are no randomized trials that have evaluated the impact of contrast agent use on the accuracy of DSE.

METHODS

Patients referred for stress testing with dobutamine echocardiography underwent 2 DSE studies: 1 with and 1 without a contrast agent, at least 4 h apart in a randomized order and within a 24-h period.

RESULTS

A total of 101 patients underwent both DSE studies. Similar hemodynamics were achieved during the 2 stress testing sessions. The use of a contrast agent improved the percentage of segments adequately visualized at baseline (from 72 +/- 24% to 95 +/- 8%) and more so at peak stress (67 +/- 28% to 96 +/- 7%); both p < 0.001. Interpretation of wall motion with high confidence also increased with contrast agent use from 36% to 74% (p < 0.001). Segment visualization with the use of a contrast agent improved in all views, but was more pronounced in the apical views. In unenhanced DSE, 36% of studies were normal, 51% had ischemia, and 8% were uninterpretable-all of which became interpretable with the use of a contrast agent. When compared with angiography (n = 92; 55 patients with CAD), accurate detection of ischemia was higher with contrast-enhanced studies versus nonenhanced studies (p = 0.02). As endocardial visualization and confidence of interpretation decreased in unenhanced studies, a greater impact of the use of a contrast agent on DSE accuracy was observed (p < 0.01).

CONCLUSIONS

During dobutamine stress echocardiography, contrast agent administration improves endocardial visualization at rest and more so during stress, leading to a higher confidence of interpretation and greater accuracy in evaluating CAD. The lesser the endocardial border visualization, the higher the impact of contrast echocardiography on accuracy.

American Society of Echocardiography Consensus Statement on the Clinical Applications of Ultrasonic Contrast Agents in Echocardiography

ACCREDITATION STATEMENT: The American Society of Echocardiography (ASE) is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The ASE designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit.trade mark Physicians should only claim credit commensurate with the extent of their participation in the activity. The American Registry of Diagnostic Medical Sonographers and Cardiovascular Credentialing International recognize the ASE's certificates and have agreed to honor the credit hours toward their registry requirements for sonographers. The ASE is committed to resolving all conflict-of-interest issues, and its mandate is to retain only those speakers with financial interests that can be reconciled with the goals and educational integrity of the educational program. Disclosure of faculty and commercial support sponsor relationships, if any, have been indicated.

TARGET AUDIENCE

This activity is designed for all cardiovascular physicians, cardiac sonographers, and nurses with a primary interest and knowledge base in the field of echocardiography; in addition, residents, researchers, clinicians, sonographers, and other medical professionals having a specific interest in contrast echocardiography may be included.

OBJECTIVES

Upon completing this activity, participants will be able to: 1. Demonstrate an increased knowledge of the applications for contrast echocardiography and their impact on cardiac diagnosis. 2. Differentiate the available ultrasound contrast agents and ultrasound equipment imaging features to optimize their use. 3. Recognize the indications, benefits, and safety of ultrasound contrast agents, acknowledging the recent labeling changes by the US Food and Drug Administration (FDA) regarding contrast agent use and safety information. 4. Identify specific patient populations that represent potential candidates for the use of contrast agents, to enable cost-effective clinical diagnosis. 5. Incorporate effective teamwork strategies for the implementation of contrast agents in the echocardiography laboratory and establish guidelines for contrast use. 6. Use contrast enhancement for endocardial border delineation and left ventricular opacification in rest and stress echocardiography and unique patient care environments in which echocardiographic image acquisition is frequently challenging, including intensive care units (ICUs) and emergency departments. 7. Effectively use contrast echocardiography for the diagnosis of intracardiac and extracardiac abnormalities, including the identification of complications of acute myocardial infarction. 8. Assess the common pitfalls in contrast imaging and use stepwise, guideline-based contrast equipment setup and contrast agent administration techniques to optimize image acquisition.

Safety of ultrasound contrast agents in stress echocardiography

Definity and Optison are perflutren-based ultrasound contrast agents used in echocardiography. United States Food and Drug Administration warnings regarding serious cardiopulmonary reactions and death after Definity administration highlighted the limited safety data in patients who undergo contrast stress echocardiography. From 1998 and 2007, 2,022 patients underwent dobutamine stress echocardiography and 2,764 underwent exercise stress echocardiography with contrast at the Cleveland Clinic. The echocardiographic database, patient records, and the Social Security Death Index were reviewed for the timing and cause of death, severe adverse events, arrhythmias, and symptoms. Complication rates for contrast dobutamine stress echocardiography and exercise stress echocardiography were compared with those in a control group of 5,012 patients matched for test year and type who did not receive contrast. Ninety-five percent of studies were performed in outpatients. There were no differences in the rates of severe adverse events (0.19% vs 0.17%, p = 0.7), death within 24 hours (0% vs 0.04%, p = 0.1), cardiac arrest (0.04% vs 0.04%, p = 0.96), and sustained ventricular tachycardia (0.2% vs 0.1%, p = 0.32) between patients receiving and not receiving intravenous contrast, respectively. In conclusion, severe adverse reactions to intravenous contrast agents during stress echocardiography are uncommon. Contrast use does not add to the baseline risk for severe adverse events in patients who undergo stress echocardiography.

Contrast echocardiography: evidence for clinical use

The failure of echocardiography to give diagnostically useful information in a significant proportion of patients has led to the development of specific contrast agents to enhance imaging. Suitable contrast media must have the ability to modify ultrasound characteristics, be capable of crossing the pulmonary capillary bed, show stability over the duration of a procedure, offer low blood solubility with low toxicity and be rapidly eliminated. The current generation of ultrasound contrast agents comprises microbubbles of a high molecular-weight gas encapsulated in a shell of phospholipid or protein. A review of the clinical evidence shows that these agents are clinically effective in enhancing echocardiographic imaging. They enable the rescue of failed procedures, often sparing patients from invasive tests, but appear not to add to the burden of side effects. Indeed, the benefits of using contrast agents in stress echocardiography have been recommended in recently published American Society of Echocardiography guidelines. Myocardial contrast echocardiography has now developed to the stage where assessment of myocardial perfusion for the detection of coronary artery disease is possible with the same diagnostic accuracy as radionuclide imaging. However, in comparison with the latter technique, it is less expensive, is more portable, and avoids the use of ionizing radiation. It is precisely the ability of myocardial contrast echocardiography to simultaneously assess function and perfusion at the bedside that has given it a unique role in clinical practice. This review provides an overview of the clinical evidence supporting the efficacy of contrast echocardiography in the assessment of myocardial structure, function, and perfusion.

Left ventricular opacification for the diagnosis of coronary artery disease with stress echocardiography: an angiographic study of incremental benefit and cost-effectiveness

BACKGROUND

Left ventricular opacification (LVO) improves image quality at stress echocardiography (SE). We examined whether routine use of LVO adds incremental benefit and is cost-effective for diagnosis of coronary artery disease (CAD).

METHODS

Contrast pharmacologic and/or exercise SE was performed in 135 patients (81 men; 56 +/- 10 years) undergoing coronary angiography. Observers sequentially interpreted first standard, then LVO images; a positive SE was defined by resting or inducible wall motion abnormality in > or = 2 segments. Coronary artery disease (75 patients, 119 territories) was defined as > 50% stenosis. Three cost-effectiveness models were studied, and a sensitivity analysis was performed.

RESULTS

Left ventricular opacification increased the sensitivity of SE (80%-91%; P = .03), including single-vessel CAD (65%-87%; P = .04), with no significant change in specificity (72%-77%; P = NS). Left ventricular opacification was of benefit to 14% of patients, unrelated to resting image quality. Use of LVO in all patients added 59% to the cost of the procedure (P < .001), at a cost of $1069 per additional correct diagnosis. In a cost-effectiveness model based on cardiac outcomes after SE, LVO resulted in an increase in total cost of $1069. A 3.7% improvement in sensitivity resulted in a negative cost to identify CAD, but even 15% to 20% improvements in specificity failed to balance the cost of contrast for exclusion of CAD.

CONCLUSIONS

Left ventricular opacification adds significant incremental diagnostic benefit to standard SE, especially single-vessel CAD. Despite improved sensitivity, the use of contrast in all patients was not cost-effective when analyzed with a model based on previously published patient outcomes.

Contrast echocardiography

Myocardial contrast echocardiography (MCE) is a noninvasive imaging technique that relies on the ultrasound detection of microbubble contrast agents. These agents are confined to the intravascular space thereby producing signal enhancement from the blood pool. This review encompasses many of the key concepts regarding the clinical application of MCE. The first section focuses on the composition, safety, and biokinetics of ultrasound contrast agents. Then we discuss new ultrasound imaging methodology that has been developed to enhance detection of contrast agent and to assess perfusion at the tissue level. Next, the clinical applications of contrast ultrasound are reviewed. These include enhancement of the cardiac chambers for better assessment of cardiac function and masses, myocardial perfusion imaging for the detection of coronary artery disease, and the assessment of myocardial viability and microvascular reflow. Finally, we discuss some of the future applications for MCE, which include molecular imaging of disease and drug/gene delivery. The overall aim of the review is to update the clinician on state-of-the-art MCE and how it can be applied in patients with cardiovascular disease.

Clinical utility of contrast-enhanced echocardiography

Over the past three decades, echocardiography has become a major diagnostic tool in the arsenal of clinical cardiology for real-time imaging of cardiac dynamics. More and more, cardiologists' decisions are based on images created from ultrasound wave reflections. From the time ultrasound imaging technology provided the first insight into a human heart, our diagnostic capabilities have increased exponentially as a result of our growing knowledge and developing technologies. One of the most intriguing developments that brought about a decade-long combination of expectations and disappointments was the introduction of echocardiographic contrast agents. Despite repeated waves of controversy regarding the readiness of this technology for clinical use, it has overcome multiple hurdles and currently provides useful clinical information that helps cardiologists to diagnose heart disease accurately. Since the initial reports on the use of ultrasound contrast media such as agitated saline or renografin, the major advances in the field of contrast echocardiography have included (1) the development of stable perfluorocarbon-filled microbubbles, frequently referred to as second-generation contrast agents; and (2) the development of contrast-targeted nonlinear imaging modes, such as harmonic imaging, pulse inversion, and power modulation, which allow consistent real-time visualization of these agents. These contrast agents in conjunction with the new imaging technology constitute powerful tools that improve our ability to evaluate left ventricular function and myocardial perfusion, and allow differential diagnosis of thrombi and intravascular masses. In this manuscript, we briefly review some of the literature that has provided the scientific basis for the use of echocardiographic contrast agents in the context of these important variables.

New technologies applied to stress echocardiography: myocardial contrast echocardiography

The development of new echocardiographic contrast agents that can be injected intravenously and can opacify left-sided cardiac chambers has offered a contribution in the field of stress-echocardiography for two main reasons: (1) the improvement of visualization of the endocardial border and thus facilitating recognition of wall motion abnormalities during pharmacological stress or physical exercise; and (2) the obtaining of information on myocardial perfusion during stress examinations. This review will consider: (1) the improvement of diagnostic accuracy during pharmacological stress or physical exercise obtained with the administration of echo-contrast agents; (2) the results of major studies for comparison of the myocardial contrast echocardiography technique versus single-photon emission computed tomography (SPECT) and coronary angiography; (3) the added value for studying perfusion other than wall motion analysis during stress echo; and (4) the advantages and limitations of different stress modalities. New multicenter studies should now definitively clarify the choice of the best contrast agents and create protocols for myocardial contrast echocardiography using different methods of image acquisition in order to unify the diagnostic process before a 'label approved' for perfusion of contrast echocardiographic agents. Finally, caution should be considered when contrast agents are used in the acute phase of myocardial infarction or ischemia.

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.