Effect of intravenous contrast for left ventricular opacification and border definition on sensitivity and specificity of dobutamine stress echocardiography compared with coronary angiography in technically difficult patients

Stress echocardiography in heart failure patients: additive value and caveats

Heart failure (HF) is a clinical syndrome characterized by well-defined signs and symptoms due to structural and/or myocardial functional impairment, resulting in raised intracardiac pressures and/or inadequate cardiac stroke volume at rest or during exercise. This could derive from direct ischemic myocardial injury or other chronic pathological conditions, including valvular heart disease (VHD) and primary myocardial disease. Early identification of HF etiology is essential for accurate diagnosis and initiation of early and appropriate treatment. Thus, the presence of accurate means for early diagnosis of HF symptoms or subclinical phases is fundamental, among which echocardiography being the first line diagnostic investigation. Echocardiography could be performed at rest, to identify overt structural and functional abnormalities or during physical or pharmacological stress, in order to elicit subclinical myocardial function impairment e.g. wall motion abnormalities and raised ventricular filling pressures. Beyond diagnosis of ischemic heart disease, stress echocardiography (SE) has recently shown its unique value for the evaluation of diastolic heart failure, VHD, non-ischemic cardiomyopathies and pulmonary hypertension, with recommendations from international societies in several clinical settings. All these features make SE an important additional tool, not only for diagnostic assessment, but also for prognostic stratification and therapeutic management of patients with HF. In this review, the unique value of SE in the evaluation of HF patients will be described, with the objective to provide an overview of the validated methods for each setting, particularly for HF management.

Current Concepts and Future Applications of Non-Invasive Functional and Anatomical Evaluation of Coronary Artery Disease

Over the last decades, significant advances have been achieved in the treatment of coronary artery disease (CAD). Proper non-invasive diagnosis and appropriate management based on functional information and the extension of ischemia or viability remain the cornerstone in the fight against adverse CAD events. Stress echocardiography and single photon emission computed tomography are often used for the evaluation of ischemia. Advancements in non-invasive imaging modalities such as computed tomography (CT) coronary angiography and cardiac magnetic resonance imaging (MRI) have not only allowed non-invasive imaging of coronary artery lumen but also provide additional functional information. Other characteristics regarding the plaque morphology can be further evaluated with the latest modalities achieving a morpho-functional evaluation of CAD. Advances in the utilization of positron emission tomography (PET), as well as software advancements especially regarding cardiac CT, may provide additional prognostic information to a more evidence-based treatment decision. Since the armamentarium on non-invasive imaging modalities has evolved, the knowledge of the capabilities and limitations of each imaging modality should be evaluated in a case-by-case basis to achieve the best diagnosis and treatment decision. In this review article, we present the most recent advances in the noninvasive anatomical and functional evaluation of CAD.

Review of ultrasound contrast agents in current clinical practice with special focus on DEFINITY® in cardiac imaging

Echocardiography is the most widely used noninvasive modality to evaluate the structure and function of the cardiac muscle in daily practice. However, up to 15-20% of echocardiograms are considered suboptimal. To enable accurate assessment of cardiac function and wall motion abnormality, the use of ultrasound microbubble contrast has shown substantial benefits in cases of salvaging nondiagnostic studies and enhancing the diagnostic accuracy in daily practice. DEFINITY^® is a perflutren based, lipid shelled microbubble contrast agent, which is US FDA approved for left ventricular opacification. The basis of ultrasound microbubbles, its development, and the clinical role of DEFINITY (characteristics, indications and case examples, side effect profile and existing evidence) is the subject of discussion in this review.

Three Decades of Ultrasound Contrast Agents: A Review of the Past, Present and Future Improvements

Initial reports from the 1960s describing the observations of ultrasound contrast enhancement by tiny gaseous bubbles during echocardiographic examinations prompted the development of the first ultrasound contrast agent in the 1980s. Current commercial contrast agents for echography, such as Definity, Optison, Sonazoid and SonoVue, have proven to be successful in a variety of on- and off-label clinical indications. Whereas contrast-specific technology has seen dramatic progress after the introduction of the first approved agents in the 1990s, successful clinical translation of new developments has been limited during the same period, while understanding of microbubble physical, chemical and biologic behavior has improved substantially. It is expected that for a successful development of future opportunities, such as ultrasound molecular imaging and therapeutic applications using microbubbles, new creative developments in microbubble engineering and production dedicated to further optimizing microbubble performance are required, and that they cannot rely on bubble technology developed more than 3 decades ago.

Is 3D Dobutamine stress echocardiography ready for prime time? Diagnostic and prognostic implications

Aims

Compare the diagnostic accuracy and prognostic value of echo contrast enhanced 2D and 3D Dobutamine stress echocardiography (DSE).

Methods and results

We included 718 patients indicated for DSE. All had standard 2D, and contrast enhanced left ventricular opacification (LVO) for 2D and 3D acquisitions at rest and peak stress. Chi-square test was done to assess relationship between DSE result and early revascularization. Kaplan–Meier plots with Logistic regression analysis predicted late major adverse cardiovascular events (MACE) at a maximum follow-up of 84 months. The mean age was 63 ± 13 years (61% males) and follow-up was obtained in 692/718 (96.4%) patients. Only 32% had excellent baseline image quality. The DSE was abnormal in 19.4% patients on 2D, in 17.1% on 2D-LVO and in 19.1% on 3D-LVO. Early revascularization was performed in, respectively, 32.8%, 45.8%, and in 48.5% of stress-positive 2D, 2D-LVO, and 3D-LVO studies. After excluding the 66 patients receiving early revascularization 68/626 (10.9%) had MACE at a maximum follow-up of 84 months. Kaplan–Meier plots showed that stress-positive 2D-LVO and 3D-LVO studies not receiving early revascularization when assessed separately and combined had significantly worse outcomes for MACE compared with stress-negative patients (OR 3.69; 95% CI: 1.54–8.87; P = 0.011, OR 4.54; 95% CI: 1.72–12.93; P = 0.008, and OR 7.07, 95% CI: 1.62–25.16; P = 0.001, respectively).

Conclusion

Combined use of 2D- and 3D-LVO DSE is ready for prime time considering the feasibility, improved diagnostic accuracy and prognostic value.

High-definition blood flow imaging in the assessment of left ventricular function: Initial experience and comparison with contrast echocardiography

OBJECTIVES

The study aimed to assess the accuracy and reproducibility of the high-definition blood flow imaging (HD-Flow) in evaluation of left ventricular (LV) function by comparison with contrast echocardiography (Contrast).

BACKGROUND

Contrast improves endocardial border visualization and assists in precise assessment of LV function. HD-Flow, a novel ultrasound technique that enhances blood flow discrimination in LV, could possibly be used for improving endocardial border definition without contrast.

METHODS

Eighty patients with technically limited transthoracic echocardiograms had HD-Flow, and contrast performed sequentially. LV endocardial visualization, image acquisition time, wall motion, volumes, ejection fraction (EF), stroke volume (SV), and stroke volume index (SVI) were compared. Inter- and intra-observer agreements were examined in a randomly selected subgroup.

RESULTS

Both HD-Flow and contrast significantly improved the percentage of the well-defined endocardial border segments (71% at baseline vs 94.1% by HD-Flow vs 94.9% by contrast, X²  = 401, P < 0.001). The acquisition time for HD-Flow was significantly less when compared to contrast (2.13 ± 1.18 minutes vs 10.96 ± 3.51 minutes, P < 0.001). LV end-diastolic volume (EDV), end-systolic volume (ESV), EF, SV, and SVI measured by the two methods correlated well (EDVr = 0.97, ESVr = 0.96, EFr = 0.90, SVr = 0.77, SVIr = 0.74, all P < 0.001). In comparison, HD-Flow was neither significantly different in detecting LV wall motion abnormality nor in EF, SV, and SVI measurements, but slightly underestimated LV volumes.

CONCLUSIONS

HD-Flow imaging is feasible and user-friendly in enhancing LV endocardial definition. This technique is useful in both qualitative and quantitative assessment of LV function.

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.

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.

Ultrasound contrast agents

Endoscopic ultrasound (EUS) plays an important role in imaging of the mediastinum and abdominal organs. Since the introduction of US contrast agents (UCA) for transabdominal US, attempts have been made to apply contrast-enhanced US techniques also to EUS. Since 2003, specific contrast-enhanced imaging was possible using EUS. Important studies have been published regarding contrast-enhanced EUS and the characterization of focal pancreatic lesions, lymph nodes, and subepithelial tumors. In this manuscript, we describe the relevant UCA, their application, and specific image acquisition as well as the principles of image tissue characterization using contrast-enhanced EUS. Safety issues, potential future developments, and EUS-specific issues are reviewed.

Update on the safety and efficacy of commercial ultrasound contrast agents in cardiac applications

Ultrasound contrast agents (UCAs) are currently used throughout the world in both clinical and research settings. The concept of contrast-enhanced ultrasound imaging originated in the late 1960s, and the first commercially available agents were initially developed in the 1980s. Today's microbubbles are designed for greater utility and are used for both approved and off-label indications. In October 2007, the US Food and Drug Administration (FDA) imposed additional product label warnings that included serious cardiopulmonary reactions, several new disease-state contraindications, and a mandated 30 min post-procedure monitoring period for the agents Optison and Definity. These additional warnings were prompted by reports of cardiopulmonary reactions that were temporally related but were not clearly attributable to these UCAs. Subsequent published reports over the following months established not only the safety but also the improved efficacy of clinical ultrasound applications with UCAs. The FDA consequently updated the product labeling in June 2008 and reduced contraindications, although it continued to monitor select patients. In addition, a post-marketing program was proposed to the sponsors for a series of safety studies to further assess the risk of UCAs. Then in October 2011, the FDA leadership further downgraded the warnings after hearing the results of the post-marketing data, which revealed continued safety and improved efficacy. The present review focuses on the use of UCAs in today's clinical practice, including the approved indications, a variety of off-label uses, and the most recent data, which affirms the safety and efficacy of UCAs.

Feasibility and prognostic value of stress echocardiography in obese, morbidly obese, and super obese patients referred for bariatric surgery

BACKGROUND

Stress echocardiography (SE) is clinically used in the risk stratification and prognosis of patients with coronary artery disease. Due to multiple comorbidities, obese patients have increased risk of adverse cardiovascular events perioperatively in noncardiac surgery. The aim of this study was to investigate the feasibility of SE in morbidly obese patients undergoing bariatric surgery.

METHODS

Consecutive patients referred for SE for preoperative evaluation prior to bariatric surgery from January 2002 to July 2011 formed the study cohort. Contrast was used to define the endocardial border in patients with poor acoustic windows. All-cause mortality data were obtained from Social Security Death Index.

RESULTS

Six hundred fifty-two patients (47 ± 10 years, 84% females) with the mean follow-up of 3.0 ± 2.7 years and mean body mass index (BMI) of 47 ± 9 kg/m² were included in this analysis. Dobutamine SE was performed in 65% of patients compared to exercise SE in 35%. Patients with higher BMI were more likely to undergo dobutamine SE (P < 0.0001). Similarly, incidence of poor acoustic windows and contrast use was higher in those with increased BMI (P < 0.001). Contrast use was higher in patients undergoing dobutamine SE (39%) versus exercise (25%), (P = 0.002). 19 patients (3%) had an abnormal SE and 8 patients (1.2%) died during the follow-up period.

CONCLUSION

Stress echocardiography is feasible in the morbidly obese patients. Patients with higher BMI were more likely to undergo dobutamine SE and have higher incidence of poor acoustic windows and contrast use.

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.

Use of contrast echocardiography in intensive care and at the emergency room

Bedside echocardiography in emergency room (ER) or in intensive care unit (ICU) is an important tool for managing critically ill patients, to obtain a timely accurate diagnosis and to immediately stratify the risk to the patient’s life. It may also render invasive monitoring unnecessary. In these patients, contrast echocardiography may improve quality of imaging and also may provide additional information, especially regarding myocardial perfusion in those with suspected coronary artery disease. This article focuses on the principle of contrast echocardiography and the clinical information that can be obtained according to the most frequent presentations in ER and ICU.

Advanced echocardiographic techniques

Echocardiography has advanced significantly since its first clinical use. The move towards more accurate imaging and quantification has driven this advancement. In this review, we will briefly focus on three distinct but important recent advances, three‐dimensional (3D) echocardiography, contrast echocardiography and myocardial tissue imaging. The basic principles of these techniques will be discussed as well as current and future clinical applications.

Clinical usefulness of SonoVue contrast echocardiography: the Thoraxcentre experience

Although other imaging techniques, such as magnetic resonance imaging and computer tomography, are becoming more and more important in cardiology, two-dimensional echocardiography is still the most used technique in clinical cardiology. Quantification of left ventricular function and dimensions is important because therapeutic strategies, for example implanting an ICD after myocardial infarction, are based on ejection fraction measurements. Because of the sometimes low quality of echocardiographic images we started to use an ultrasound contrast agent and in this article we describe our experiences with SonoVue, a second-generation contrast agent, over a threeyear period in the Thoraxcentre. (Neth Heart J 2007;15:55-60.).

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.

Exercise echocardiography

Exercise echocardiography has been used for 30 years. It is now considered a consolidated technique for the diagnosis and risk stratification of patients with known or suspected coronary artery disease (CAD). Of the stress echocardiography techniques, it represents the first choice for patients who are able to exercise. Given that the cost-effectiveness and safety of stress echocardiography are higher than those of other imaging techniques, its use is likely to be expanded further. Recent research has also proposed this technique for the evaluation of cardiac pathology beyond CAD. Although the role of new technology is promising, the assessment of cardiac function relies on good quality black and white harmonic images.

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.

Quantitative three-dimensional wall motion analysis predicts ischemic region size and location

Stress echocardiography is an important screening test for coronary artery disease. Currently, cardiologists rely on visual analysis of left ventricular (LV) wall motion abnormalities, which is subjective and qualitative. We previously used finite-element models of the regionally ischemic left ventricle to develop a wall motion measure, 3DFS, for predicting ischemic region size and location from real-time 3D echocardiography (RT3DE). The purpose of this study was to validate these methods against regional blood flow measurements during regional ischemia and to compare the accuracy of our methods to the current state of the art, visual scoring by trained cardiologists. We acquired RT3DE images during 20 brief (<2 min) coronary occlusions in dogs and determined ischemic region size and location by microsphere-based measurement of regional perfusion. We identified regions of abnormal wall motion using 3DFS and by blinded visual scoring. 3DFS predicted ischemic region size well (correlation r (2) = 0.64 against microspheres, p < 0.0001), reducing error by more than half compared to visual scoring (8 +/- 9% vs. 19 +/- 14%, p < 0.05), while localizing the ischemic region with equal accuracy. We conclude that 3DFS is an objective, quantitative measure of wall motion that localizes acutely ischemic regions as accurately as wall motion scoring while providing superior quantification of ischemic region size.

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.

Noninvasive imaging of the heart and coronary arteries

There are multiple imaging modalities currently available to noninvasively evaluate the heart and coronary arteries. Choosing the most appropriate modality depends on the pertinent clinical question and the underlying patient characteristics. This article provides an overview of the fields of echocardiography, myocardial perfusion imaging, cardiac computed tomography, and cardiac magnetic resonance imaging, with particular attention to specific clinical applications for cardiac surgery patients.

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.

Comparison of pressure measurement, dobutamine contrast stress echocardiography and SPECT for the evaluation of intermediate coronary stenoses. The COMPRESS trial

BACKGROUND

DSE and SPECT are two well-established methods to non-invasively investigate the functional significance of coronary artery stenoses in patients with coronary artery disease. The measurement of Fractional Flow Reserve has emerged a new invasive reference standard for lesion specific quantification of coronary artery stenoses. The objective of our prospective study was to compare sensitivity and specificity of Dobutamine Stress Echocardiography (DSE) and Single Photon Emission Computer tomography (SPECT) with the pressure derived Fractional Flow Reserve (FFR) for the identification of hemodynamic relevant coronary lesions in patients with predominately coronary multivessel disease and angiographically intermediate stenoses.

METHODS

Inclusion criteria were a coronary lesion of 50-75% diameter stenosis by visual assessment in patients with known or suspected CAD. SPECT, DSE and FFR testing was performed within one week of coronary angiography.

RESULTS

The study comprised 48 consecutive symptomatic patients. In 41 cases, a coronary multivessel disease was present. Mean FFR was 0.80 +/- 0.13 (0.41-1.0). Overall sensitivity of DSE and SPECT was 67% and 69% whereas specificity reached 77% and 87%. However, sensitivity was significantly reduced if the target lesion was located distally. DSE showed poor results if the lesions were located in the circumflex artery or if a history of prior myocardial infarctions was present.

CONCLUSION

DSE and SPECT are both useful methods for the non-invasive assessment of coronary artery disease. DSE showed reasonable combination of sensitivity and specificity even in patients with multivessel disease. Although use of noninvasive stress tests is only limited in patients with prior myocardial infarctions and invasive stress testing should be preferred in these patients.

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.

Regional diastolic contour abnormalities during contrast stress echocardiography: improved detection of coronary artery disease

BACKGROUND

Use of contrast improves detection of systolic regional wall motion abnormalities (RWMAs) during stress echocardiography. We evaluated regional diastolic contour abnormalities (RDCAs) that were associated with coronary artery disease (CAD).

METHODS

From August of 2003 to September of 2004, we evaluated 89 patients who underwent contrast stress echocardiography (CSE) and coronary angiography within a 3-month period ("invasive" group) and 17 patients with lower CAD risk who underwent CSE only ("reference" group).

RESULTS

RDCAs were present in 73 patients in the invasive group and were associated with higher Framingham risk scores (relative risk, 3.6; 95% confidence interval, 1.9-6.6). RDCAs were present in 1 patient in the reference group. When combined with RWMA, RDCA improved sensitivity of CSE from 78% to 97% and specificity from 26% to 59% (diagnostic threshold for CAD was 70% stenosis).

CONCLUSION

RDCAs were a novel observation associated with higher CAD risk and improved the diagnostic accuracy of CSE.

Safety of contrast administration for endocardial enhancement during stress echocardiography compared with noncontrast stress

The aim was to evaluate the safety of stress echocardiography using contrast (CE) for endocardial enhancement compared with a noncontrast (NCE) cohort in a large nonselect population. The recent Food and Drug Administration warning cited lack of data for safety regarding the use of contrast in conjunction with stress echocardiography. A detailed record review was performed for 5,069 consecutive patients who underwent stress echocardiography (58% pharmacologic, 42% exercise) during an 8-year period. Contrast use, hemodynamics, and adverse clinical and electrocardiographic events were evaluated until time of discharge from the laboratory. Contrast was administered to 2,914 patients (58%) and was higher in in-patients (66%) and during dobutamine stress (67%). Compared with the NCE group, the CE group was older (median age 61 vs 58 years) and had more depressed left ventricular ejection fraction <50% (14% vs 11%; all p <0.001). The CE group experienced more chest pain (11% vs 8%; p = 0.001), back pain (0.6% vs 0.05%; p <0.001), and premature ventricular contractions (odds ratio 1.42, 95% confidence interval 1.19 to 1.69, p <0.001). There was no sustained ventricular tachycardia, ventricular fibrillation, cardiac arrest, or death in either group. One uncomplicated acute myocardial infarction and 1 anaphylactoid reaction occurred in the CE group, and none occurred in the NCE group (p = 0.51). Rates of clinically significant arrhythmias were similar in both groups (CE 2.1% vs NCE 1.9%; p = 0.8). In conclusion, although CE of echocardiographic images was used more often in patients with a higher cardiac risk profile, the risk of major adverse events was very small in both the CE and NCE stress echocardiography cohorts.

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.

Head to head comparison of transesophageal and transthoracic contrast-enhanced echocardiography during dobutamine administration for the detection of coronary artery disease

Dobutamine stress echocardiography (DSE) has been shown to be a very useful non-invasive technique for the detection of coronary artery disease. However, inadequate transthoracic images preclude the use of DSE in a significant proportion of patients. Transesophageal (TEE) or transthoracic contrast echocardiography (CE) can however overcome this limitation. The comparison between the two techniques has never been investigated during a stress test. Therefore, we designed a prospective study to compare DSE-CE and DSE-TEE for the detection of coronary artery disease in patients with poor echo image quality. We studied 42 patients scheduled for quantitative coronary angiography. Prospective DSE-CE and DSE-TEE with maximum one day interval were performed in a random order. Significant coronary artery disease was detected in 30 patients, nine with single vessel disease and 21 with multivessel disease. Sensitivity of DSE was higher with CE than with TEE (90% vs 87%, p=NS). There was no significant difference with respect to specificity in both groups (100% vs 92%, p=NS). The diagnostic accuracy was similar in both groups (93% vs 88%, NS). The kappa value for identical interpretation of a stress echocardiography study was nearly identical with both modalities 0.75 to 0.78. In poorly echogenic patients, DSE-CE is a valuable alternative for the detection of myocardial ischemia in comparison with DSE-TEE. Because DSE-CE is more comfortable than TEE, it should be used in patients with suboptimal transthoracic echocardiograms for the evaluation of coronary artery disease during DSE.

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.

High-frame rate, full-view myocardial elastography with automated contour tracking in murine left ventricles in vivo

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high resolution and high precision. The purpose in this paper was to isolate the left ventricle from other structures for better displacement and strain visualization. Using a high-resolution (30 MHz) ultrasound system and a retrospective electrocardiogram (ECG)-gating technique, an extremely high frame rate (up to 8 kHz) was previously shown achievable for full-view (12-mm times 12-mm) myocardial elastography in the murine left ventricle. In vivo experiments were performed in anesthetized normal and infarcted mice [one day after left anterior descending (LAD) coronary artery ligation]. Radio frequency (RF) signals of the left ventricle (LV) in the long-axis view and the associated ECG were simultaneously acquired, with the ECG allowing gating of the RF signals. Incremental axial displacement of the myocardium was estimated using a one-dimensional (1-D) cross-correlation function. The cumulative displacement and strain then were calculated from the incremental displacement. In this paper, after manual selection of 40-50 points along the endo-and epicardial borders in the first frame of the cine-loop, myocardial contour was automatically tracked across the entire LV throughout a full cardiac cycle, which correctly determined the region of interest (ROI) for better interpretation. The cine-loop of the cumulative displacement and strain in one cardiac cycle, in both the normal and infarcted cases, showed that motion and deformation in the infarcted myocardium were significantly reduced, and that the infarcted region underwent thinning, rather than thickening, during systole. High precision of the displacement estimation, due to high frequency (30 MHz) and high frame rate (up to 8 kHz) available with this system, allowed for automated tracking of a manually-initialized myocardial contour over an entire cardiac cycle. High frame rate, full-view myocardial elastography with automated contour tracking could provide regional strain information of the LV throughout an entire cardiac cycle, and characterize normal as well as detect abnormal myocardial function, such as an infarction. The method of automated contour tracking can further enhance the capability of the elastographic technique with minimal user intervention while providing accurate functional information for the detection of disease throughout the entire cardiac cycle.

The value of contrast dobutamine stress echocardiography on detecting coronary artery disease in overweight and obese patients

BACKGROUND

Dobutamine stress echocardiography (DSE) is an established method of detecting myocardial ischemia. Its diagnostic accuracy solely depends on wall motion assessment. Clear visibility of the left ventricular endocardium is essential for reliable assessment of a wall motion abnormality. However, incremental benefits of contrast DSE for the detection of coronary artery disease (CAD) have not been demonstrated in overweight or obese patients.

OBJECTIVES

The purpose of the present study was to test the incremental benefits of contrast DSE in detecting CAD in overweight or obese patients.

METHODS

Sixty-two overweight or obese patients (body mass index 26 kg/m(2) to 33 kg/m(2)) underwent DSE with or without contrast and coronary angiography. Contrast-enhanced images were achieved at rest and during peak DSE after administration of SonoVue (Bracco Diagnostics Inc, Italy) or Optison (Mallinckrodt, USA). The endocardial border resolution for each myocardial segment was graded as 0, 1 or 2. A total of 992 segments from 62 subjects were analyzed. The results of DSE with or without contrast were compared with the findings on angiography.

RESULTS

The differences in the score grading between the two groups with or without contrast, at rest and during peak DSE were statistically significant (P<0.001). The sensitivity, specificity and accuracy of contrast DSE in detecting CAD, compared with the studies without contrast, were improved (82% versus 70%, 78% versus 67% and 81% versus 69%, respectively).

CONCLUSIONS

SonoVue and Optison can enhance left ventricular endocardial border delineation in overweight or obese patients, optimizing the evaluation of wall motion both at rest and during peak stress. This increases the diagnostic value of DSE in detecting CAD.

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.

Effects of gender on prognosis of patients with known or suspected coronary artery disease undergoing contrast-enhanced dobutamine stress echocardiography

BACKGROUND

Gender differences in the predictors of outcome among patients with known or suspected coronary artery disease (CAD) undergoing contrast-enhanced dobutamine stress echocardiography (CE-DSE) have not been completely determined.

METHODS AND RESULTS

Follow-up (30+/-17 months) data for 581 men and 309 women with known or suspected CAD who underwent CE-DSE (mean age: 66 years) were obtained. Hard cardiac events included cardiac death and nonfatal myocardial infarction. Total cardiac events included hard cardiac events, unstable angina, congestive heart failure, and late revascularization (>3 months). Cardiac events occurred in 123 male and 50 female patients. Positive results for CE-DSE were associated with worse prognosis in both men and women (2-year total event free rate: 73.5% vs 88.2% in men, p<0.0001, 80.3% vs 91.3% in women, p<0.01). Addition of CE-DSE results, including abnormal left ventricular end-systolic volume response and left ventricular ejection fraction at peak stress <50%, to the clinical and rest echocardiography model provided incremental information for predicting total cardiac events (increase in chi-square value for the model from 60 to 72, p<0.001) in men and (increase in chi-square value for the model from 17 to 32, p<0.001) in women.

CONCLUSIONS

CE-DSE provides incremental information for predicting future cardiac events in both men and women.