Contrast echocardiography: a practical guideline from the British Society of Echocardiography.

Ultrasound contrast agents (UCAs) have a well-established role in clinical cardiology. Contrast echocardiography has evolved into a routine technique through the establishment of contrast protocols, an excellent safety profile, and clinical guidelines which highlight the incremental prognostic utility of contrast enhanced echocardiography. This document aims to provide practical guidance on the safe and effective use of contrast; reviews the role of individual staff groups; and training requirements to facilitate its routine use in the echocardiography laboratory.

Viability and Outcomes With Revascularization or Medical Therapy in Ischemic Ventricular Dysfunction: A Prespecified Secondary Analysis of the REVIVED-BCIS2 Trial.

Importance: In the Revascularization for Ischemic Ventricular Dysfunction (REVIVED-BCIS2) trial, percutaneous coronary intervention (PCI) did not improve outcomes for patients with ischemic left ventricular dysfunction. Whether myocardial viability testing had prognostic utility for these patients or identified a subpopulation who may benefit from PCI remained unclear. Objective: To determine the effect of the extent of viable and nonviable myocardium on the effectiveness of PCI, prognosis, and improvement in left ventricular function. Design, Setting, and Participants: Prospective open-label randomized clinical trial recruiting between August 28, 2013, and March 19, 2020, with a median follow-up of 3.4 years (IQR, 2.3-5.0 years). A total of 40 secondary and tertiary care centers in the United Kingdom were included. Of 700 randomly assigned patients, 610 with left ventricular ejection fraction less than or equal to 35%, extensive coronary artery disease, and evidence of viability in at least 4 myocardial segments that were dysfunctional at rest and who underwent blinded core laboratory viability characterization were included. Data analysis was conducted from March 31, 2022, to May 1, 2023. Intervention: Percutaneous coronary intervention in addition to optimal medical therapy. Main Outcomes and Measures: Blinded core laboratory analysis was performed of cardiac magnetic resonance imaging scans and dobutamine stress echocardiograms to quantify the extent of viable and nonviable myocardium, expressed as an absolute percentage of left ventricular mass. The primary outcome of this subgroup analysis was the composite of all-cause death or hospitalization for heart failure. Secondary outcomes were all-cause death, cardiovascular death, hospitalization for heart failure, and improved left ventricular function at 6 months. Results: The mean (SD) age of the participants was 69.3 (9.0) years. In the PCI group, 258 (87%) were male, and in the optimal medical therapy group, 277 (88%) were male. The primary outcome occurred in 107 of 295 participants assigned to PCI and 114 of 315 participants assigned to optimal medical therapy alone. There was no interaction between the extent of viable or nonviable myocardium and the effect of PCI on the primary or any secondary outcome. Across the study population, the extent of viable myocardium was not associated with the primary outcome (hazard ratio per 10% increase, 0.98; 95% CI, 0.93-1.04) or any secondary outcome. The extent of nonviable myocardium was associated with the primary outcome (hazard ratio, 1.07; 95% CI, 1.00-1.15), all-cause death, cardiovascular death, and improvement in left ventricular function. Conclusions and Relevance: This study found that viability testing does not identify patients with ischemic cardiomyopathy who benefit from PCI. The extent of nonviable myocardium, but not the extent of viable myocardium, is associated with event-free survival and likelihood of improvement of left ventricular function. Trial Registration: ClinicalTrials.gov Identifier: NCT01920048.

Feasibility, efficacy and safety of exercise stress echocardiography during the COVID-19 pandemic.

OBJECTIVE: To assess the feasibility, efficacy and safety of performing exercise stress echocardiography (ESE) for the assessment of myocardial ischaemia during the COVID-19 pandemic. METHODS AND RESULTS: Baseline data were collected prospectively on 740 consecutive patients (mean age 61.4 years, 56.8% males), referred for a stress echocardiogram (SE), who underwent ESE between July 2020 (immediate post lockdown) and January 2021 according to national safety guidelines, in addition to patients wearing masks during ESE. Retrospective analysis was performed on follow-up data for outcomes. Propensity score matching was used to compare workload achieved during ESE pre-COVID-19, in 768 consecutive patients who underwent ESE between May 2014 and May 2015. Of the 725 (97.9%) diagnostic tests obtained, 69 (9.3%) demonstrated significant inducible ischaemia (≥3 segments) with no serious adverse events. Of the 61 patients who underwent coronary angiography, 51 (83%) demonstrated flow-limiting coronary artery disease. During a mean follow-up period of 4.6 months, one first-cardiac event was recorded.Compliance with mask-wearing throughout ESE was seen in 98.7% of patients. Of the 17 healthcare professionals performing ESE, none contracted COVID-19 during this period. SE service performance increased to 96.8% of prepandemic levels (100%) from 26.6% at the start of July 2020 to the end of December 2020.Propensity-matched data showed no significant difference in exercise workload between patients undergoing ESE during and prepandemic. CONCLUSION: Performing ESE during the COVID-19 pandemic, with safety measures in place, is feasible, efficacious and safe. It impacted on the time patients were waiting to undergo a diagnostic test and yielded appropriate outcomes.Service evaluation authorisation of research capability numberSE20/059.

Low Transvalvular Flow Rate Predicts Mortality in Patients With Low-Gradient Aortic Stenosis Following Aortic Valve Intervention.

OBJECTIVES: This study aimed to assess the value of low transvalvular flow rate (FR) for the prediction of mortality compared with low stroke volume index (SVi) in patients with low-gradient (mean gradient: <40 mm Hg), low aortic valve area (<1 cm2) aortic stenosis (AS) following aortic valve intervention. BACKGROUND: Transaortic FR defined as stroke volume/left ventricular ejection time is also a marker of flow; however, no data exist comparing the relative prognostic value of these 2 transvalvular flow markers in patients with low-gradient AS who had undergone valve intervention. METHODS: We retrospectively followed prospectively assessed consecutive patients with low-gradient, low aortic valve area AS who underwent aortic valve intervention between 2010 and 2014 for all-cause mortality. RESULTS: Of the 218 patients with mean age 75 ± 12 years, 102 (46.8%) had low stroke volume index (SVi) (<35 ml/m2), 95 (43.6%) had low FR (<200 ml/s), and 58 (26.6%) had low left ventricular ejection fraction <50%. The concordance between FR and SVi was 78.8% (p < 0.005). Over a median follow-up of 46.8 ± 21 months, 52 (23.9%) deaths occurred. Patients with low FR had significantly worse outcome compared with those with normal FR (p < 0.005). In patients with low SVi, a low FR conferred a worse outcome than a normal FR (p = 0.005), but FR status did not discriminate outcome in patients with normal SVi. By contrast, SVi did not discriminate survival either in patients with normal or low FR. Low FR was an independent predictor of mortality (p = 0.013) after adjusting for age, clinical prognostic factors, European System for Cardiac Operative Risk Evaluation II, dimensionless velocity index, left ventricular mass index, left ventricular ejection fraction, heart rate, time, type of aortic valve intervention, and SVi (p = 0.59). CONCLUSIONS: In patients with low-gradient, low valve area aortic stenosis undergoing aortic valve intervention, low FR, not low SVi, was an independent predictor of medium-term mortality.

Fully Automatic Myocardial Segmentation of Contrast Echocardiography Sequence Using Random Forests Guided by Shape Model.

Myocardial contrast echocardiography (MCE) is an imaging technique that assesses left ventricle function and myocardial perfusion for the detection of coronary artery diseases. Automatic MCE perfusion quantification is challenging and requires accurate segmentation of the myocardium from noisy and time-varying images. Random forests (RF) have been successfully applied to many medical image segmentation tasks. However, the pixel-wise RF classifier ignores contextual relationships between label outputs of individual pixels. RF which only utilizes local appearance features is also susceptible to data suffering from large intensity variations. In this paper, we demonstrate how to overcome the above limitations of classic RF by presenting a fully automatic segmentation pipeline for myocardial segmentation in full-cycle 2-D MCE data. Specifically, a statistical shape model is used to provide shape prior information that guide the RF segmentation in two ways. First, a novel shape model (SM) feature is incorporated into the RF framework to generate a more accurate RF probability map. Second, the shape model is fitted to the RF probability map to refine and constrain the final segmentation to plausible myocardial shapes. We further improve the performance by introducing a bounding box detection algorithm as a preprocessing step in the segmentation pipeline. Our approach on 2-D image is further extended to 2-D+t sequences which ensures temporal consistency in the final sequence segmentations. When evaluated on clinical MCE data sets, our proposed method achieves notable improvement in segmentation accuracy and outperforms other state-of-the-art methods, including the classic RF and its variants, active shape model and image registration.

Lower Transaortic Flow Rate Is Associated With Increased Mortality in Aortic Valve Stenosis.

OBJECTIVES: The association of transaortic flow rate (FR) with outcomes was tested in 1,661 patients with aortic valve stenosis (AS) in the SEAS (Simvastatin and Ezetimibe in Aortic Stenosis) study. BACKGROUND: Low transaortic flow may complicate grading of AS. However, the association of lower transaortic FR with adverse outcomes has not been reported. METHODS: Transaortic FR was calculated from Doppler-derived stroke volume in milliliters divided by systolic ejection time in seconds and considered low if <200 ml/s. The association of transaortic FR with cardiovascular and all-cause mortality during 4.3-year follow-up was tested in time-varying Cox regression models run with aortic valve replacement as competing risk and reported as hazard ratio (HR) and 95% confidence interval (CI). RESULTS: Low transaortic FR was found in 21% of patients at baseline. Patients with low transaortic FR were older, had lower systemic arterial compliance and left ventricular mass, and included more women and patients with inconsistently graded severe AS and low stroke volume index (<35 ml/m2) (p < 0.01 for all). Low in-study transaortic FR was associated with higher rates of cardiovascular and all-cause mortality both in unadjusted analyses (HR: 2.56 [95% CI: 1.62 to 4.04]; and HR: 1.93 [95% CI: 1.35 to 2.75], respectively; p < 0.001 for both) and after adjustment for age, sex, randomized study treatment, hypertension, stroke volume index <35 ml/m2, LV mass, and mean aortic gradient (HR: 2.79 [95% CI: 1.65 to 4.73]; and HR: 1.90 [95% CI: 1.27 to 2.84], respectively; p < 0.01 for both). CONCLUSIONS: In patients with AS without known cardiovascular disease or diabetes, low transaortic FR was independently associated with higher rates of cardiovascular and all-cause mortality. (An Investigational Drug on Clinical Outcomes in Patients With Aortic Stenosis (Narrowing of the Major Blood Vessel of the Heart) (MK-0653A-043 AM4); NCT00092677).

Reproducible Computer-Assisted Quantification of Myocardial Perfusion with Contrast-Enhanced Ultrasound.

Myocardial perfusion can be quantified by myocardial contrast echocardiography (MCE) and is used for the diagnosis of coronary artery disease (CAD). However, existing MCE quantification software is highly operator dependent and has poor reproducibility and ease of usage. The aim of this study was to develop robust and easy-to-use software that can perform MCE quantification accurately, reproducibly and rapidly. The developed software has the following features: (i) semi-automatic segmentation of the myocardium; (ii) automatic rejection of MCE data with poor image quality; (iii) automatic computation of perfusion parameters such as myocardial blood flow (MBF). MCE sequences of 18 individuals (9 normal, 9 with CAD) undergoing vasodilator stress with dipyridamole were analysed quantitatively using the software. When evaluated against coronary angiography, the software achieved a sensitivity of 71% and a specificity of 91% for hyperemic MBF. With the automatic rejection algorithm, the sensitivity and specificity further improved to 77% and 94%, respectively. For MBF reproducibility, the percentage agreement is 85% (κ = 0.65) for inter-observer variability and 88% (κ = 0.72) for intra-observer variability. The intra-class correlation coefficients are 0.94 (inter-observer) and 0.96 (intra-observer). The time taken to analyse one MCE sequence using the software is about 3 min on a PC. The software has exhibited good diagnostic performance and reproducibility for CAD detection and is rapid and user-friendly.

Contrast-enhanced ultrasonography vs B-mode ultrasound for visualization of intima-media thickness and detection of plaques in human carotid arteries.

BACKGROUND: Carotid intima-media thickness (IMT) and plaque are recognized markers of increased risk for cerebrovascular events. Accurate visualization of the IMT and plaques is dependent upon image quality. Ultrasound contrast agents improve image quality during echocardiography-this study assessed whether contrast-enhanced ultrasound (CEUS) improves carotid IMT visualization and plaque detection in an asymptomatic population. METHODS & RESULTS: Individuals free from known cardiovascular disease, enrolled in a community study, underwent B-mode and CEUS carotid imaging. Each carotid artery was divided into 10 segments (far and near walls of the proximal, mid and distal segments of the common carotid artery, the carotid bulb, and internal carotid artery). Visualization of the IMT complex and plaque assessments was made during both B-mode and CEUS imaging for all enrolled subjects, a total of 175 individuals (mean age 65±9 years). Visualization of the IMT was significantly improved during CEUS compared with B-mode imaging, in both near and far walls of the carotid arteries (% IMT visualization during B-mode vs CEUS imaging: 61% vs 94% and 66% vs 95% for right and left carotid arteries, respectively, P<.001 for both). Additionally, a greater number of plaques were detected during CEUS imaging compared with B-mode imaging (367 plaques vs 350 plaques, P=.02). CONCLUSION: Contrast-enhanced ultrasound improves visualization of the intima-media complex, in both near and far walls, of the common and internal carotid arteries and permits greater detection of carotid plaques. Further studies are required to determine whether there is incremental clinical and prognostic benefit related to superior plaque detection by CEUS.

Differential Intensity Projection for Visualisation and Quantification of Plaque Neovascularisation in Contrast-Enhanced Ultrasound Images of Carotid Arteries.

Studies have reported that intraplaque neovascularisation (IPN) is closely correlated with plaque vulnerability. In this study, a new image processing approach, differential intensity projection (DIP), was developed to visualise and quantify IPN in contrast-enhanced non-linear ultrasound image sequences of carotid arteries. DIP used the difference between the local temporal maximum and the local temporal average signals to identify bubbles against tissue non-linear artefact and noise. The total absolute and relative areas occupied by bubbles within each plaque were calculated to quantify IPN. In vitro measurements on a laboratory phantom were made, followed by in vivo measurements in which 24 contrast-enhanced non-linear ultrasound image sequences of carotid arteries from 48 patients were selected and motion corrected. The results using DIP were compared with those obtained by maximum intensity projection (MIP) and visual assessment. The results indicated that DIP can significantly reduce non-linear propagation tissue artefacts and is much more specific in detecting bubble signals than MIP, being able to reveal microbubble signals that are buried in tissue artefacts in the corresponding MIP image. A good correlation was found between microvascular area (MVA) (r = 0.83, p < 0.001)/microvascular density (r = 0.77, p < 0.001) obtained using DIP and the corresponding expert visual grades, comparing favourably to r = 0.26 and 0.23 obtained using MIP on the same data. In conclusion, the proposed method exhibits great potential in quantification of IPN in contrast-enhanced ultrasound images of carotid arteries.

Contrast enhancement of carotid adventitial vasa vasorum as a biomarker of radiation-induced atherosclerosis.

PURPOSE: Abnormal proliferation of adventitial vasa vasorum (vv) occurs early at sites of atherosclerosis and is thought to be an early biomarker of vascular damage. Contrast-enhanced ultrasound (CEUS) can detect this process. Its usefulness in irradiated arteries as a measure of accelerated atherosclerosis is unknown. This study investigates contrast intensity in carotid adventitia as an early marker of radiation-induced damage in head and neck cancer (HNC) patients. MATERIALS/METHODS: Patients with HNC treated with a wedged-pair and matched neck technique or hemi-neck radiotherapy (RT) (unirradiated side as control) at least 2years previously were included. Patients had been prescribed a dose of at least 50Gy to the neck. CEUS was performed on both carotid arteries and a region of interest was selected in the adventitia of the far wall of both left and right distal common carotid arteries. Novel quantification software was used to compare the average intensity per pixel between irradiated and unirradiated arteries. RESULTS: 48 patients (34 males) with median age of 59.2years (interquartile range (IQR) 49.2-64.2) were included. The mean maximum point dose to the irradiated artery was 61.2Gy (IQR 52.6-61.8) and 1.1Gy (IQR 1.0-1.8Gy) to the unirradiated side. The median interval from RT was 59.4months (IQR 41-88.7). There was a significant difference in the mean (SD) contrast intensity per pixel on the irradiated side (1.1 (0.4)) versus 0.96 (0.34) on the unirradiated side (p=0.01). After attenuation correction, the difference in mean contrast intensity per pixel was still significant (1.4 (0.58) versus 1.2 (0.47) (p=0.02). Previous surgery or chemotherapy had no effect on the difference in contrast intensity between the 2 sides of the neck. Mean intensity per pixel did not correlate to traditional risk prediction models (carotid intima-medial thickness, QSTROKE score). CONCLUSIONS: Proliferation of vv is demonstrated by increased contrast intensity in irradiated carotid arteries. This may be a useful, independent biomarker of radiation-induced carotid atherosclerosis when used as a tool to quantify neovascularization.

Plaque Neovascularization Is Increased in Human Carotid Atherosclerosis Related to Prior Neck Radiotherapy: A Contrast-Enhanced Ultrasound Study.

OBJECTIVES: The aim of this study was to determine the effect of radiotherapy (RT) on intraplaque neovascularization (IPN) in human carotid arteries. BACKGROUND: Exposure of the carotid arteries to RT during treatment for head and neck cancer is associated with increased risk for stroke. However, the effect of RT on IPN, a precursor to intraplaque hemorrhage and thus associated with plaque vulnerability, is unknown. METHODS: In this cross-sectional study, patients who had undergone unilateral RT for head and neck cancer ≥2 years previously underwent B-mode and contrast-enhanced ultrasound of both RT-side and non-RT-side carotid arteries. Presence of IPN during contrast-enhanced ultrasound was judged semiquantitatively as grade 0 (absent), grade 1 (present but limited to plaque base), or grade 2 (extensive and noted within plaque body). RESULTS: Of 49 patients studied, 38 (78%) had plaques. The number of plaques was significantly greater in the RT than the non-RT arteries. Overall, 48 of 64 RT-side plaques (75%) had IPN compared with 9 of 23 non-RT-side (39%) plaques (p = 0.002). Among patients with plaques, IPN was present in 81% of patients with RT-side plaques and 41% of patients with non-RT-side plaques (p = 0.004). Grade 0 IPN was significantly more common in patients with non-RT-side plaques (25% vs. 61%; p = 0.002), whereas grade 2 plaques were more common on the RT side (31% vs. 9%; p = 0.03). The only clinical variable that predicted the presence or absence of IPN was RT laterality. CONCLUSIONS: This is the first study in humans to reveal a significant association between RT and the presence and extent of IPN. This may provide insights into the mechanisms underlying the increased stroke risk among survivors of head and neck cancer treated by RT.

Carotid intima-medial thickness as a marker of radiation-induced carotid atherosclerosis.

PURPOSE: Arterial thickening is a precursor to atherosclerosis. Carotid intima-medial thickness (CIMT), a measure of arterial thickening, is a validated surrogate for prediction of cerebrovascular events. This study investigates CIMT as an early marker of radiation-induced carotid artery damage. MATERIALS/METHODS: Head and neck cancer patients treated with radiotherapy (RT) (minimum dose of 50 Gy) to one side of the neck (unirradiated side as control) at least 2 years previously were included. CIMT was measured in 4 arterial segments: proximal, mid, distal common carotid artery (CCA), and bifurcation and were compared to corresponding unirradiated segments. CIMT measurements >75th percentile of a reference population were considered abnormal and at increased cerebrovascular risk. RESULTS: 50 patients (34 males) with a median age of 58 years (interquartile range (IQR) 50-62) were included. The mean maximum dose to the irradiated and unirradiated artery was 53 Gy (standard deviation (SD) 13 Gy) and 1.9 Gy (SD 3.7 Gy), respectively. Mean CIMT was significantly greater in irradiated versus unirradiated arteries: proximal CCA (0.76 mm ± 0.15 vs 0.68 mm ± 0.14 (p<0.0001), mid CCA (0.74 mm ± 0.2 vs 0.68 mm ± 0.16 (p=0.01), distal CCA (0.77 mm ± 0.2 vs 0.68 mm ± 0.15 (p=0.004), and bifurcation (0.85 mm ± 0.25 vs 0.72 mm ± 0.17 (p=0.001). For all arterial segments, a significantly greater number of CIMT measurements were abnormal on the irradiated side (proximal: p=0.004, mid: p=0.05, distal: p=0.005, bifurcation: p=0.03). There was no effect of time from RT, age, smoking status, surgery and chemotherapy on CIMT difference (irradiated-unirradiated) in all segments. CONCLUSIONS: CIMT is increased after RT and may be a useful marker of radiation-induced carotid atherosclerosis. There appears to be no additional effect of other atherosclerotic risk factors on CIMT following RT.

Arterial Stiffness as a Biomarker of Radiation-Induced Carotid Atherosclerosis.

Arterial stiffness is thought to be a precursor to atherosclerosis. Conventional arterial stiffness parameters as potential biomarkers of radiation-induced damage were investigated. Patients with head and neck cancer treated with radiotherapy ≥2 years previously to one side of the neck were included. The unirradiated side was the internal control. Beta stiffness index (B) and elastic modulus (Ep) were used to assess arterial stiffness and were measured in proximal, mid, and distal common carotid artery (CCA) and compared with the corresponding unirradiated segments. Fifty patients (68% male; median age 58 years; interquartile range 50-62) were included. Mean ± standard deviation maximum doses to irradiated and unirradiated arteries were 53 ± 13 and 1.9 ± 3.7 Gy, respectively. Differences in B were not significant. Significant differences in Ep were demonstrated-proximal CCA: 1301 ± 1223 versus 801 ± 492 (P < .0001), mid CCA: 1064 ± 818 versus 935.5 ± 793 (P < .0001), and distal CCA: 1267 ± 1084 versus 775.3 ± 551.9 (P < .0001). Surgery had no impact on arterial stiffness. Arterial stiffness is increased in irradiated arteries, in keeping with radiation-induced damage. Prospective data may show an association between arterial stiffness and atherosclerosis in this setting.