Values of three-dimensional speckle tracking imaging for the diagnosis of coronary artery disease

Background: Coronary artery disease (CAD) is a top life-threatening disease and early and sensitive detection of CAD remains a challenge. This study aimed to assess the value of three-dimensional speckle tracking imaging (3D-STI) in diagnosing CAD patients and investigate the parameters of 3D-STI associated with disease severity. Methods: A total of 260 suspected CAD patients who met the study criteria underwent coronary angiography within one week after the ultrasound examination. Based on the examination results, 142 patients were confirmed to have CAD (CAD group), while 118 patients were classified as non-CAD (NCAD group). Age, gender, family history, smoking status, diabetes, hypertension, dyslipidemia, electrocardiogram, BMI, heart rate, and left ventricular ejection fraction were compared between the two groups. Additionally, 3D-STI parameters including left ventricular global radial strain (GRS), left ventricular global longitudinal strain (GLS), left ventricular global area strain (GAS), and left ventricular global circumferential strain (GCS) were analyzed. Results: No significant differences were found between the CAD and NCAD groups in terms of demographics, smoking history, physiological measurements, and common comorbidities such as diabetes mellitus and dyslipidemia. However, when comparing the 3D-STI parameters, all four parameters, including GLS, GRS, GCS, and GAS, were significantly different in the CAD group compared to the NCAD group. The results suggest that 3D-STI parameters have diagnostic value for CAD, and their changes are associated with CAD severity. Conclusions: Combined detection of these parameters enhances diagnostic accuracy compared to individual detection.

Echocardiographic assessment of left ventricular mechanics in individuals with mitral valve prolapse: a systematic review and meta-analysis

PURPOSE

During the last decade, a number of echocardiographic studies have employed speckle tracking echocardiography (STE) for assessing myocardial deformation properties in individuals with mitral valve prolapse (MVP), reporting not univocal results. Accordingly, we performed a systematic review and meta-analysis to summarize the main findings of these studies and to examine the overall influence of MVP on left ventricular (LV) global longitudinal strain (GLS).

METHODS

All echocardiographic studies assessing conventional echoDoppler parameters and myocardial strain indices in MVP individuals vs. controls without MVP, selected from PubMed and EMBASE databases, were included. The risk of bias was assessed by using the National Institutes of Health (NIH) Quality Assessment of Case-Control Studies. Continuous data (LV-GLS) were pooled as a standardized mean difference (SMD) comparing MVP group with healthy controls. The overall SMD of LV-GLS was calculated using the random-effect model.

RESULTS

The full-texts of 15 studies with 1088 individuals with MVP and 591 healthy controls were analyzed. Average LV-GLS magnitude was significantly, even though modestly, reduced in MVP individuals in comparison to controls (19.4 ± 3.4% vs. 21.1 ± 2.8%, P < 0.001). The overall effect of MVP on LV-GLS was small-to-medium (SMD - 0.54, 95%CI -0.76,-0.32, P < 0.001). Substantial heterogeneity was detected for the included studies, with an overall I2 statistic value of 75.9% (P < 0.001). Egger's test for a regression intercept gave a P-value of 0.58, indicating no publication bias. On meta-regression analysis, none of the moderators (the age, the percentage of females among MVP individuals, body mass index, heart rate and systolic blood pressure of MVP individuals, the degree of mitral regurgitation, the type of ultrasound machine employed for strain echocardiographic imaging and finally the beta blocker treatment) was significantly associated with effect modification (all P < 0.05). Regional strain analysis, performed by two-third of the studies, highlighted a more enhanced reduction in myocardial strain parameters at level of the LV basal infero-lateral segments in all directions (longitudinal, circumferential and radial), with apical sparing.

CONCLUSIONS

The longitudinal strain impairment detected in MVP individuals is more regional than global, with peculiar involvement of the LV basal infero-lateral segments and relative apical sparing pattern.

Pleural lung sliding quantification using a speckle tracking technology: A feasibility study on 30 healthy volunteers

INTRODUCTION

Speckle tracking technology quantifies lung sliding and detects lung sliding abolition in case of pneumothorax on selected ultrasound loops through the analysis of acoustic markers.

OBJECTIVES

We aimed to test the ability of speckle tracking technology to quantify lung sliding using a pleural strain value (PS).

METHODS

We performed a prospective study in 30 healthy volunteers in whom we assessed the pleural speckle tracking using ultrasound loops. Seven breathing conditions with and without non-invasive ventilation were tested. Two observers analyzed the ultrasound loops in four lung areas (anterior and posterior, left and right) and compared the obtained PS values. The first endpoint was to determine the feasibility of the PS measurement in different breathing conditions. The secondary endpoints were to assess the intra- and inter-observer's reliability of the measurement to compare PS values between anterior and posterior lung areas and to explore their correlations with the measured tidal volume.

RESULTS

We analyzed 1624 ultrasound loops from 29 patients after one volunteer's exclusion. Feasibility of this method was rated at 90.8 [95%CI: 89.6 - 92.4]%. The intra-observer reliability measured through Intraclass Correlation Coefficients was 0.96 [95%CI: 0.91-0.98] and 0.93 [95%CI: 0.86-0.97] depending on the operator. The inter-observer reliability was 0.89 [95%CI: 0.78-0.95]. The PS values were significantly lower in the anterior lung areas compared with the posterior areas in all breathing conditions. A weak positive correlation was found in all the lung areas when a positive end expiratory pressure was applied with r = 0.26 [95%CI: 0.12;0.39]; p < 0.01.

CONCLUSION

Speckle tracking lung sliding quantification with PS was applicable in most conditions with an excellent intra- and inter-observer reliability. More studies in patients under invasive mechanical ventilation are needed to explore the correlation between PS values of pleural sliding and tidal volumes.

CLINICAL REGISTRATION

NCT05415605.

Increasing region of interest width reduces neonatal circumferential strain

OBJECTIVE

There is growing interest in speckle tracking echocardiography-derived strain as a measure of left ventricular function in neonates. However, knowledge gaps remain regarding the effect of image acquisition and processing parameters on circumferential strain measurements. The aim of this study was to evaluate the effect of using different region of interest (ROI) widths on speckle tracking derived circumferential strain in healthy neonates.

METHODS

Thirty healthy-term-born neonates were examined with speckle-tracking echocardiography in the short-axis view. Circumferential strain values were acquired and compared using two different ROI widths. Furthermore, strain values in the different vendor-defined wall layers were also compared.

RESULTS

Increasing ROI width led to a decrease in global circumferential strain (GCS) in the midwall and epicardial layers, the respective decreases in strain being -23.4 ± .6% to -22.0 ± 1.1%, p < .0001 and 18.5 ± 1.7% to -15.6 ± 2.0%, p < .0001. Segmental analyses were consistent with these results, apart from two segments in the midwall. There was no statistically significant effect on strain for the endocardial layer. A gradient was seen where strain increased from the epicardial to endocardial layers.

CONCLUSION

Increasing ROI width led to a decrease in GCS in the midwall and epicardium. There is an increase in circumferential strain when moving from the epicardial toward the endocardial layer. Clinicians wishing to implement circumferential strain into their practice should consider ROI width variation as a potential confounder in their measurements.

Feasibility of left atrial strain assessment using cardiac computed tomography in patients with paroxysmal atrial fibrillation

PURPOSE

To evaluate the feasibility of left atrial strain (LAS) assessment using cardiac computed tomography (CT) in patients with paroxysmal atrial fibrillation (PAF).

METHODS

This retrospective single-center study included 98 patients with PAF who underwent cardiac CT and echocardiography before the first catheter ablation. LAS was analyzed using cardiac CT (CT-LAS) and speckle-tracking echocardiography (STE; STE-LAS). LA reservoir (LASr), conduit (LASc), and pump strain (LASp) were calculated by averaging LAS measured in 4- and 2-chamber views. The results were compared using Pearson's correlation coefficients, paired t-tests, and Bland-Altman analysis. Intraclass correlation coefficients (ICCs) were used to evaluate reproducibility.

RESULTS

CT-LAS could be analyzed in all patients, while STE-LAS could be analyzed in 53 (54%) patients. LASr, LASc, and LASp showed significant correlations between CT- and STE-LAS: LASr, r = 0.68, p < 0.001; LASc, r = 0.47, p < 0.001; LASp, r = 0.67, p < 0.001. LASr, LASc, and LASp of CT- and STE-LAS were 23.7 ± 6.0% and 22.1 ± 6.7%, 11.1 ± 3.6% and 11.1 ± 4.1%, and 12.6 ± 4.6% and 11.0 ± 4.1%, respectively. LASr and LASp were significantly higher in CT-LAS than that in STE-LAS (p = 0.023 for LASr and p = 0.001 for LASp). CT-LAS showed excellent reproducibility. The intra- and interobserver ICCs were 0.96 to 0.99 and 0.89 to 0.90, respectively.

CONCLUSION

CT-LAS was successfully analyzed in more patients than STE-LAS and was highly reproducible. The findings suggest that CT-LAS is feasible for patients with PAF.

Cardiac Mechanics Evaluation in Preschool-Aged Children with Preterm Birth History: A Speckle Tracking and 4D Echocardiography Study

Background: The premature-born adult population is set to grow significantly, and prematurity has emerged as an important cardiovascular risk factor. We aimed to comprehensively assess cardiac mechanics and function in a cohort of ex-preterm preschoolers. Methods: Ex-preterm children (<30 weeks of gestation), aged 2 to 5 years, underwent transthoracic 2D, speckle-tracking, and 4D echocardiography. The findings were compared with 19 full-term children. Results: Our cohort of 38 children with prematurity history showed a normal morpho-functional echocardiographic assessment. However, compared to controls, the indexed 3D end-diastolic volumes of ventricular chambers were reduced (left ventricle 58.7 ± 11.2 vs. 67.2 ± 8.5 mL/m2; right ventricle 50.3 ± 10.4 vs. 57.7 ± 11 mL/m2; p = 0.02). Left ventricle global and longitudinal systolic function were worse in terms of fraction shortening (32.9% ± 6.8 vs. 36.5% ± 5.4; p = 0.05), ejection fraction (59.2% ± 4.3 vs. 62.3% ± 3.7; p = 0.003), and global longitudinal strain (-23.6% ± 2.4 vs. -25.5% ± 1.7; p = 0.003). Finally, we found a reduced left atrial strain (47.4% ± 9.7 vs. 54.9% ± 6.8; p = 0.004). Conclusions: Preschool-aged ex-preterm children exhibited smaller ventricles and subclinical impairment of left ventricle systolic and diastolic function compared to term children. Long-term follow-up is warranted to track the evolution of these findings.

Changes in left atrial function following two regimens of combined exercise training in patients with ischemic cardiomyopathy: a pilot study

Purpose

Left atrial dysfunction has shown to play a prognostic role in patients with ischemic cardiomyopathy (ICM) and is becoming a therapeutic target for pharmacological and non-pharmacological interventions. The effects of exercise training on the atrial function in patients with ICM have been poorly investigated. In the present study, we assessed the effects of a 12-week combined training (CT) program on the left atrial function in patients with ICM.

Methods

We enlisted a total of 45 clinically stable patients and randomly assigned them to one of the following three groups: 15 to a supervised CT with low-frequency sessions (twice per week) (CTLF); 15 to a supervised CT with high-frequency sessions (thrice per week) (CTHF); and 15 to a control group following contemporary preventive exercise guidelines at home. At baseline and 12 weeks, all patients underwent a symptom-limited exercise test and echocardiography. The training included aerobic continuous exercise and resistance exercise. The analysis of variance (ANOVA) was used to compare within- and inter-group changes.

Results

At 12 weeks, the CTLF and CTHF groups showed a similar increase in the duration of the ergometric test compared with the control (ANOVA p < 0.001). The peak atrial longitudinal strain significantly increased in the CTHF group, while it was unchanged in the CTLF and control groups (ANOVA p = 0.003). The peak atrial contraction strain presented a significant improvement in the CTHF group compared with the CTLF and control groups. The left ventricular global longitudinal strain significantly increased in both the CTHF and the CTLF groups compared with the control group (ANOVA p = 0.017). The systolic blood pressure decreased in the CTHF and CTLF groups, while it was unchanged in the control group. There were no side effects causing the discontinuation of the training.

Conclusions

We demonstrated that a CT program effectively improved atrial function in patients with ICM in a dose-effect manner. This result can help with programming exercise training in this population.

Blood volume contributes to the mechanical synchrony of the myocardium during moderate and high intensity exercise in women

PURPOSE

Whether blood volume (BV) primarily determines the synchronous nature of the myocardium remains unknown. This study determined the impact of standard blood withdrawal on left ventricular mechanical dyssynchrony (LVMD) in women.

METHODS

Transthoracic speckle-tracking echocardiography and central hemodynamic measurements were performed at rest and during moderate- to high-intensity exercise in healthy women (n = 24, age = 53.6 ± 16.3 year). LVMD was determined via the time to peak standard deviation (TPSD) of longitudinal and transverse strain and strain rates (LSR, TSR). Measurements were repeated within a week period immediately after a 10% reduction of BV.

RESULTS

With intact BV, all individuals presented cardiac structure and function variables within normative values of the study population. Blood withdrawal decreased BV (5.3 ± 0.7 L) by 0.5 ± 0.1 L. Resting left ventricular (LV) end-diastolic volume (- 8%, P = 0.040) and passive filling (- 16%, P = 0.001) were reduced after blood withdrawal. No effect of blood withdrawal was observed for any measure of LVMD at rest (P ≥ 0.225). During exercise at a fixed submaximal workload (100 W), LVMD of myocardial longitudinal strain (LS TPSD) was increased after blood withdrawal (36%, P = 0.047). At peak effort, blood withdrawal led to increased LVMD of myocardial transverse strain rate (TSR TPSD) (31%, P = 0.002). The effect of blood withdrawal on TSR TPSD at peak effort was associated with LV concentric remodeling (r = 0.59, P = 0.003).

CONCLUSION

Marked impairments in the mechanical synchrony of the myocardium are elicited by moderate blood withdrawal in healthy women during moderate and high intensity exercise.

Impact of temporal and spatial resolution on atrial feature tracking cardiovascular magnetic resonance imaging

BACKGROUND

Myocardial deformation assessment by cardiovascular magnetic resonance-feature tracking (CMR-FT) has incremental prognostic value over volumetric analyses. Recently, atrial functional analyses have come to the fore. However, to date recommendations for optimal resolution parameters for accurate atrial functional analyses are still lacking.

METHODS

CMR-FT was performed in 12 healthy volunteers and 9 ischemic heart failure (HF) patients. Cine sequences were acquired using different temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial resolution parameters (high 1.5 × 1.5 mm in plane and 5 mm slice thickness, standard 1.8 × 1.8 × 8 mm and low 3.0 × 3.0 × 10 mm). Inter- and intra-observer reproducibility were calculated.

RESULTS

Increasing temporal resolution is associated with higher absolute strain and strain rate (SR) values. Significant changes in strain assessment for left atrial (LA) total strain occurred between 20 and 30 frames/cycle amounting to 2,5-4,4% in absolute changes depending on spatial resolution settings. From 30 frames/cycle onward, absolute strain values remained unchanged. Significant changes of LA strain rate assessment were observed up to the highest temporal resolution of 50 frames/cycle. Effects of spatial resolution on strain assessment were smaller. For LA total strain a general trend emerged for a mild decrease in strain values obtained comparing the lowest to the highest spatial resolution at temporal resolutions of 20, 40 and 50 frames/cycle (p = 0.006-0.046) but not at 30 frames/cycle (p = 0.140).

CONCLUSION

Temporal and to a smaller extent spatial resolution affect atrial functional assessment. Consistent strain assessment requires a standard spatial resolution and a temporal resolution of 30 frames/cycle, whilst SR assessment requires even higher settings of at least 50 frames/cycle.

Compressed sensing cine imaging with higher temporal resolution for analysis of left atrial strain and strain rate by cardiac magnetic resonance feature tracking

PURPOSE

Cardiac magnetic resonance (CMR) feature tracking (FT) is more widely used in the measurement of left atrial (LA) strain and strain rate (SR). However, in recent years, researchers have attempted to improve the low temporal resolution of CMR-FT to better capture the subtle deformations of the myocardium. The technique of compressed sensing (CS) has been applied clinically, reducing scan time while increasing temporal resolution. The purpose of this study was to explore the effect of the increased temporal resolution of CS cine sequences on the analysis of LA longitudinal strain and SR.

MATERIALS AND METHODS

Twenty-nine healthy subjects were included in the study. They underwent CMR with a reference steady-state free precession cine sequence of conventional temporal resolution (standard SSFP sequence), a cine sequence of higher temporal resolution (HT sequence), and an HT cine sequence with CS (CS HT sequence) (temporal resolution: 22.1-44.3/24.9-47.1 ms, 11.1-19.4 ms, and 8.3-19.4 ms, respectively). The standard SSFP sequence, HT sequence, and CS HT sequence were acquired in all subjects during the same scanning session. LA longitudinal strain and SR, reflecting LA reservoir, conduit, and contraction booster-pump function, were measured by CMR-FT and compared among the three sequences.

RESULTS

The measurements of LASR reservoir, conduit, and booster-pump were significantly higher on the HT and CS HT sequences than on the standard SSFP sequence. The standard SSFP sequence was correlated significantly with the HT and CS HT sequences in terms of LA strain and SR analysis, respectively. The LA strain and SR measurements also showed excellent agreement between the HT and CS HT sequences.

CONCLUSION

Higher temporal resolution led to significantly higher measured LASR values in CMR-FT. Furthermore, the addition of CS reduced scan time and did not affect LA longitudinal strain or SR analysis.

The impact of angles of insonation on left and right ventricular global longitudinal strain estimation in fetal speckle tracking echocardiography

OBJECTIVES

Two-dimensional speckle tracking echocardiography has been considered an angle-independent modality. However, current literature is limited and inconclusive on the actual impact of angle of insonation on strain values. Therefore, the primary objective of this study was to assess the impact of angles of insonation on the estimation of fetal left ventricular and right ventricular global longitudinal strain. Secondarily, the impact of different definitions for angles of insonation was investigated in a sensitivity analysis.

METHODS

This is a retrospective analysis of a prospective longitudinal cohort study with 124 healthy subjects. The analyses were based on the four-chamber view ultrasound clips taken between 18+0 and 21+6 weeks of gestation. Angles of insonation were categorized into three groups: up/down, oblique and perpendicular. The mean fetal left and right ventricular and global longitudinal strain values corresponding to these three groups were compared by an ANOVA test corrected for heteroscedasticity.

RESULTS

Fetal left and right ventricular global longitudinal strain values were not statistically different between the three angles of insonation (p-value >0.062 and >0.149, respectively). When applying another definition for angles of insonation in the sensitivity analysis, the mean left ventricular global longitudinal strain value was significantly decreased for the oblique compared to the up/down angle of insonation (p-value 0.041).

CONCLUSIONS

There is no evidence of a difference in fetal left and right ventricular global longitudinal strain between the different angles of insonation in fetal two-dimensional speckle tracking echocardiography.

The influence of pectus excavatum on cardiac kinetics and function in otherwise healthy individuals: A systematic review

BACKGROUND

A number of anterior chest wall deformities, most notably pectus excavatum (PE), may have a detrimental effect on cardiac motion and function. Interpretation of transthoracic echocardiography (TTE) and speckle-tracking echocardiography (STE) results may be hampered by the possible influence of PE on cardiac kinetics.

METHODS

A comprehensive search of all articles assessing cardiac function in PE individuals was carried out. Inclusion criteria were: 1) individuals aged >10 years; 2) studies providing objective assessment of chest deformity (Haller index). Studies that measured myocardial strain parameters in PE patients were also included.

RESULTS

The search (EMBASE and Medline) yielded a total of 392 studies, 36 (9.2%) of which removed as duplicates; a further 339 did not meet inclusion criteria. The full-texts of 17 studies were then analyzed. All studies concordantly reported impaired right ventricular volumes and function. With respect to left ventricle (LV), TTE studies uniformly demonstrated a significant impairment in conventional echoDoppler indices in PE individuals, whereas STE studies provided conflicting results. Importantly, LV functional alterations promptly reverted upon surgical correction of chest defect. In subjects with PE of mild-to-moderate severity, we observed that degree of anterior chest wall deformity, as noninvasively assessed by modified Haller index (MHI), was strongly associated with myocardial strain magnitude, in heterogenous cohorts of otherwise healthy PE individuals.

CONCLUSIONS

Clinicians should be aware that in PE individuals, TTE and STE results may not always be indicative of intrinsic myocardial dysfunction, but may be, at least in part, influenced by artifactual and/or external chest shape determinants.

Impaired cardiac mechanical synchrony revealed with increased myocardial work in women with advanced age

BACKGROUND

Whether the synchronous nature of the myocardium is sex-dependent or affected by the aging process remains unknown. This study aimed to determine the influence of sex and age on cardiac mechanical synchrony during controlled hemodynamic stress.

METHODS

Transthoracic speckle-tracking echocardiography analyses and central hemodynamics were assessed at rest and during moderate- to high-intensity exercise in healthy young (<45 yr) and older (≥45 yr) women (n = 32) and men (n = 34) matched by age, physical activity and exercise capacity. Left ventricular mechanical dyssynchrony (LVMD) was determined as the time to peak standard deviation (TPSD) of longitudinal and transverse strain and strain rates (LSR, TSR).

RESULTS

Physical activity, aerobic capacity, heart rate, blood pressure and LVMD at rest were similar between women and men in each age group (P > 0.05). The rate pressure product, an index of myocardial work, did not differ between sex and age groups at rest and during exercise at a given percentage of peak heart rate (P > 0.05). A consistent age effect was observed for transverse LVMD (P-for-age ≤ 0.011). Specifically, older women presented with marked increments (≥42 %) in TSR TPSD at all exercise levels compared with younger women (P ≤ 0.005). Sex per se did not generally affect LVMD.

CONCLUSION

A prevailing impairment of cardiac mechanical synchrony in the transverse axis of the left ventricle is revealed during conditions of elevated hemodynamic stress in women with advanced age.

Prognostic value of temporal patterns of global longitudinal strain in patients with chronic heart failure

Background

We investigated whether repeatedly measured global longitudinal strain (GLS) has incremental prognostic value over repeatedly measured left ventricular ejection fraction (LVEF) and N-terminal pro B-type natriuretic peptide (NT-proBNP), and a single "baseline" GLS value, in chronic heart failure (HF) patients.

Methods

In this prospective observational study, echocardiography was performed in 173 clinically stable chronic HF patients every six months during follow up. During a median follow-up of 2.7 years, a median of 3 (25th-75th percentile:2-4) echocardiograms were obtained per patient. The endpoint was a composite of HF hospitalization, left ventricular assist device, heart transplantation, cardiovascular death. We compared hazard ratios (HRs) for the endpoint from Cox models (used to analyze the first available GLS measurements) with HRs from joint models (which links repeated measurements to the time-to-event data).

Results

Mean age was 58 ± 11 years, 76% were men, 81% were in New York Heart Association functional class I/II, and all had LVEF < 50% (mean ± SD: 27 ± 9%). The endpoint was reached by 53 patients. GLS was persistently decreased over time in patients with the endpoint. However, temporal GLS trajectories did not further diverge in patients with versus without the endpoint and remained stable during follow-up. Both single measurements and temporal trajectories of GLS were significantly associated with the endpoint [HR per SD change (95%CI): 2.15(1.34-3.46), 3.54 (2.01-6.20)]. In a multivariable model, repeatedly measured GLS maintained its prognostic value while repeatedly measured LVEF did not [HR per SD change (95%CI): GLS:4.38 (1.49-14.70), LVEF:1.14 (0.41-3.23)]. The association disappeared when correcting for repeatedly measured NT-proBNP.

Conclusion

Temporal evolution of GLS was associated with adverse events, independent of LVEF but not independent of NT-proBNP. Since GLS showed decreased but stable values in patients with adverse prognosis, single measurements of GLS provide sufficient information for determining prognosis in clinical practice compared to repeated measurements, and temporal GLS patterns do not add prognostic information to NT-proBNP.

Vendor independent myocardial strain values in children

BACKGROUND

Two-dimensional (2D) strain imaging has become an important tool in assessing subclinical myocardial dysfunction in children. However, there are no published normal values for vendor-independent strain software. The aim of this study was to estimate 2D strain values in a cohort of healthy children using Tomtec cardiac performance analysis (CPA), a vendor-independent software.

METHODS

Transthoracic echocardiograms of healthy pediatric outpatients (0-18 years) were retrospectively analyzed from the Vanderbilt Pediatric Heart Institute using CPA. The cardiac assessment included global longitudinal strain (GLS), global longitudinal strain rate (GLSR), global circumferential strain (GCS), and global circumferential strain rate (GCSR). Mean strain values with standard deviation (SD) are reported. The Wilcoxon rank sum test, linear regression, and one-way analysis of variance were used to assess differences among the various groups.

RESULTS

Among 142 children analyzed, 79 (56%) were male, and the median age was 5.5 (range, 0-18) years. The mean (SD) strain values were GLS -19.3 ± 3.4, GLSR -1.1 ± .22; GCS -24.7 ± 4.3, GCSR -1.5 ± .28. Age accounted for <8% of the variation in GLS, GCS, and GCSR. However, for GLSR, there was a statistically significant difference between younger and older age groups with higher GLSR in the younger age group. Age accounted for ∼25% of the variation in GLSR (R2  = .25, p < 0.001). There were no significant differences in strain based on sex.

CONCLUSION

We report normal myocardial strain values in healthy children by age for strain using CPA. These values add to the growing body of literature on myocardial strain in children and provide necessary data for the interpretation of strain imaging.

Influence of temporal resolution on computed tomography feature-tracking strain measurements

PURPOSE

Temporal resolution significantly affects strain values demonstrated by Magnetic resonance feature-tracking and speckle-tracking echocardiography. We investigated the influence of R-R interval reconstruction increments on left ventricular (LV) and left atrial (LA) strain measurements of Computed tomography feature-tracking (CT-FT).

METHODS

Subjects who underwent retrospective electrocardiogram-gated coronary CT angiography (CCTA) were retrospectively included, and CCTA images were reconstructed in 5% and 10% steps throughout the entire cardiac cycle (0-100% R-R interval). LV global longitudinal strain (GLS), circumferential strain (GCS), radial strain (GRS), LA GLS, ejection fraction (EF), and left atrioventricular coupling indices were computed. We evaluated the consistency and variability of continuous variables between the two reconstruction increment groups, the demarcation between the LA conduit and contraction phases, and observer reproducibility in 20 randomly selected participants.

RESULTS

Eighty-one participants with or without cardiac disease were included. The reconstruction increment of the R-R interval significantly affected the CT-FT-derived strain values. The 5% R-R increment resulted in significantly larger absolute strain values. LV GRS had the greatest difference between the two groups. In the subgroups with heart rates greater than 80 beats per minute or impaired cardiac function, group differences were attenuated, especially for LV GLS, LV GRS, and LA GLS. The prevalence of definite demarcation between the LA conduit and contraction phases was significantly higher in the 5% R-R reconstruction increment group than in the 10% R-R reconstruction increment group. The average heart rate during CCTA scanning was a strong risk factor for indefinite demarcation, which is independent of LVEF. As average heart rate increased, so did the incidence of indefinite demarcation between the LA conduit and contraction phases. The observer reproducibility of LV and LA strain values was independent of the R-R reconstruction increment.

CONCLUSION

Reconstruction increment of the R-R interval is an important source of variation in LV and LA CT-FT strain values, especially with low heart rate and preserved cardiac function. It is essential to control the heart rate and apply a narrow R-R reconstruction increment to quantify phasic LA strain.

Ultrafast Myocardial Principal Strain Ultrasound Elastography During Stress Tests: In Vitro Validation and In Vivo Feasibility

Objective myocardial contractility assessment during stress tests aims to improve the diagnosis of myocardial ischemia. Tissue Doppler imaging (TDI) or optical flow (OF) speckle tracking echocardiography (STE) has been used to quantify myocardial contractility at rest. However, this is more challenging during stress tests due to image decorrelation at high heart rates. Moreover, stress tests imply a high frame rate which leads to a limited lateral field of view. Therefore, a large lateral field-of-view robust ultrafast myocardial regularized OF-TDI principal strain estimator has been developed for high-frame-rate echocardiography of coherently compounded transmitted diverging waves. The feasibility and accuracy of the proposed estimator were validated in vitro (using sonomicrometry as the gold standard) and in vivo stress experiments. Compared with OF strain imaging, the proposed estimator improved the accuracy of principal major and minor strains during stress tests, with an average contrast-to-noise ratio improvement of 4.4 ± 2.7 dB ( p -value < 0.01). Moreover, there was a significant correlation and a very close agreement between the proposed estimator and sonomicrometry for tested heart rates between 60 and 180 beats per minute (bpm). The averages ± standard deviations (STD) of R² and biases ± STD between them were 0.96 ± 0.04 ( p -value < 0.01) and 0.01 ± 0.03% in the axial direction, respectively; and 0.94 ± 0.02 ( p -value < 0.01) and 0.04 ± 0.06% in the lateral direction, respectively. These results suggest that the proposed estimator could be useful clinically to provide an accurate and quantitative 2-D large lateral field-of-view myocardial strain assessment at high heart rates during stress echocardiography.

Current and novel echocardiographic assessment of left ventricular systolic function in aortic stenosis-A comprehensive review

Aortic stenosis (AS) is a complex and progressive condition that can significantly reduce the quality of life and increase the incidence of premature mortality. Transthoracic echocardiography (TTE) is the gold standard imaging modality for the assessment of AS severity. While left ventricular ejection fraction (LVEF) derived from TTE is a very well-understood parameter, limitations such as high inter and intra-observer variability, insensitivity to sub-clinical dysfunction, and influence of loading conditions make LVEF a complicated and unreliable parameter. Myocardial deformation imaging has been identified as a promising parameter for identifying subclinical left ventricular dysfunction, however, this parameter is still afterload dependent. Myocardial Work is a promising novel assessment technique that accounts for afterload by combining the use of myocardial deformation imaging and non-invasive blood pressure to provide a more comprehensive assessment of mechanics beyond LVEF. This review evaluates the evidence for various echocardiographic assessment parameters used to quantify left ventricular function including myocardial work in patients with AS.

Clinical Utility of Three-Dimensional Speckle-Tracking Echocardiography in Heart Failure

Heart failure (HF) is an extremely major health problem with gradually increasing incidence in developed and developing countries. HF may lead to cardiac remodeling; thus, advanced imaging techniques are required to comprehensively evaluate cardiac mechanics. Recently, three-dimensional speckle-tracking echocardiography (3D-STE) has been developed as a novel imaging technology that is based on the three-dimensional speckle-tracking on the full volume three-dimensional datasets. Three-dimensional speckle-tracking echocardiography allows a more accurate evaluation of global and regional myocardial performance, assessment of cardiac mechanics, detection of subclinical cardiac dysfunction, and prediction of adverse clinical events in a variety of cardiovascular diseases. Therefore, this review summarizes the clinical usefulness of 3D-STE in patients with HF.

Molecular Approaches and Echocardiographic Deformation Imaging in Detecting Myocardial Fibrosis

The pathological remodeling of myocardial tissue is the main cause of heart diseases. Several processes are involved in the onset of heart failure, and the comprehension of the mechanisms underlying the pathological phenotype deserves special attention to find novel procedures to identify the site of injury and develop novel strategies, as well as molecular druggable pathways, to counteract the high degree of morbidity associated with it. Myocardial fibrosis (MF) is recognized as a critical trigger for disruption of heart functionality due to the excessive accumulation of extracellular matrix proteins, in response to an injury. Its diagnosis remains focalized on invasive techniques, such as endomyocardial biopsy (EMB), or may be noninvasively detected by cardiac magnetic resonance imaging (CMRI). The detection of MF by non-canonical markers remains a challenge in clinical practice. During the last two decades, two-dimensional (2D) speckle tracking echocardiography (STE) has emerged as a new non-invasive imaging modality, able to detect myocardial tissue abnormalities without specifying the causes of the underlying histopathological changes. In this review, we highlighted the clinical utility of 2D-STE deformation imaging for tissue characterization, and its main technical limitations and criticisms. Moreover, we focalized on the importance of coupling 2D-STE examination with the molecular approaches in the clinical decision-making processes, in particular when the 2D-STE does not reflect myocardial dysfunction directly. We also attempted to examine the roles of epigenetic markers of MF and hypothesized microRNA-based mechanisms aiming to understand how they match with the clinical utility of echocardiographic deformation imaging for tissue characterization and MF assessment.

High-Frame-Rate Speckle Tracking for Echocardiographic Stress Testing

Stress echocardiography helps to diagnose cardiac diseases that cannot easily be detected or do not even manifest at rest. In clinical practice, assessment of the stress test is usually performed visually and, therefore, in a qualitative and subjective way. Although speckle tracking echocardiography (STE) has been proposed for the quantification of function during stress, its time resolution is inadequate at high heart rates. Recently, high-frame-rate (HFR) imaging approaches have been proposed together with dedicated STE algorithms capable of handling small interframe displacements. The aim of this study was to determine if HFR STE is effective in assessing strain and strain rate parameters during echocardiographic stress testing. Specifically, stress echocardiography, at four different workload intensities, was performed in 25 healthy volunteers. At each stress level, HFR images from the apical four-chamber view were recorded using the ULA-OP 256 experimental scanner. Then, the myocardium was tracked with HFR STE, and strain and strain rate biomarkers were extracted to further analyze systolic and diastolic (early and late) peaks, as well as a short-lived isovolumic relaxation peak during stress testing. The global systolic strain response was monophasic, revealing a significant (p < 0.001) increase at low stress but then reaching a plateau. In contrast, all strain rate indices linearly increased (p < 0.001) with increasing stress level. These findings are in line with those reported using tissue Doppler imaging and, thus, indicate that HFR STE can be a useful tool in assessing cardiac function during stress echocardiography.

Left Ventricular Strain Analysis During Submaximal Semisupine Bicycle Exercise Stress Echocardiography in Childhood Cancer Survivors

Background

Childhood cancer survivors (CCSs) show relevant cardiac morbidity and mortality throughout life. Early detection is key for optimal support of patients at risk. The aim of this study was to evaluate 2‐dimensional speckle‐tracking echocardiography strain analysis during semisupine exercise stress in CCSs for detection of subclinical left ventricular dysfunction after cancer treatment.

Methods and Results

Seventy‐seven CCSs ≥1‐year postchemotherapy were prospectively examined at rest, low, and submaximal stress level and compared with a cohort of healthy adolescents and young adults (n=50). Global longitudinal strain (GLS), short axis circumferential strain, and corresponding strain rates were analyzed using vendor‐independent software. CCSs at median 7.8 years postchemotherapy showed comparable left ventricular GLS, circumferential strain, and strain rate values at all stress stages to healthy controls. Yet, prevalence of abnormal GLS (defined as <2 SD of controls reference) in CCSs was 1.3% at rest, 2.7% at low, and 8.6% at submaximal stress. In CCSs, relative change of circumferential strain from rest to submaximal stress was lower than in healthy controls, median 16.9 (interquartile range [IQR], 3.4; 28.8) % versus 23.3 (IQR, 11.3; 33.3) %, P=0.03, most apparent in the subgroups of CCSs after high‐dose anthracycline treatment and cancer diagnosis before the age of 5 years.

Conclusions

In this prospective 2‐dimensional speckle tracking echocardiography strain study, prevalence of abnormal left ventricular GLS increased with stress level reflecting impaired cardiac adaptation to exercise stress in some CCSs. However, relatively early after last chemotherapy, this did not result in significant differences of mean GLS‐, circumferential strain‐, and strain rate values between CCSs and controls at any stress level.

Myocardial Strain Imaging With Electrocardiogram-Gated and Coherent Compounding for Early Diagnosis of Coronary Artery Disease

Myocardial elastography (ME) is an ultrasound-based technique that uses radiofrequency signals for 2-D cardiac motion tracking and strain imaging at a high frame rate. Early diagnosis of coronary artery disease (CAD) is critical for timely treatment and improvement of patient outcome. The objective of this study was to assess the performance of ME radial and circumferential strains in the detection and characterization of CAD in patients. In this study, 86 patients suspected of CAD were imaged with ME prior to invasive coronary angiography (ICA). End-systolic radial and circumferential left ventricular strains were estimated in all patients in each of their perfusion territories: left anterior descending (LAD), left circumflex (LCX) and right coronary artery (RCA). ME radial strains were capable of differentiating the obstructive CAD group (55.3 ± 29.8%) from the non-obstructive CAD (72.5 ± 46.8%, p < 0.05) and no CAD groups (73.4 ± 30.4%, p < 0.05) in the RCA territory. ME circumferential strains were capable of differentiating the obstructive CAD group (-3.1 ± 7.5%) from the non-obstructive CAD (-7.2 ± 6.8%, p < 0.05) and normal (-6.9 ± 8.0%, p < 0.05) groups in the LAD territory and to differentiate the normal group (-17.1 ± 8.2%) from the obstructive (-12.8 ± 7.2%, p < 0.05) and non-obstructive CAD (-13.6 ± 8.5%, p < 0.05) groups in the RCA territory. ME circumferential strain performed better than ME radial strain in differentiating normal, non-obstructive and obstructive perfusion territories. In the LCX territory, both ME radial and circumferential strains decreased when the level of stenosis was higher. However, it was not statistically significant. The findings presented herein indicate that ME radial and circumferential estimation obtained from ECG-gated and compounded acquisitions is a promising tool for early, non-invasive and radiation-free detection of CAD in patients.

A method for direct estimation of left ventricular global longitudinal strain rate from echocardiograms

We present a new method for measuring global longitudinal strain and global longitudinal strain rate from 2D echocardiograms using a logarithmic-transform correlation (LTC) method. Traditional echocardiography strain analysis depends on user inputs and chamber segmentation, which yield increased measurement variability. In contrast, our approach is automated and does not require cardiac chamber segmentation and regularization, thus eliminating these issues. The algorithm was benchmarked against two conventional strain analysis methods using synthetic left ventricle ultrasound images. Measurement error was assessed as a function of contrast-to-noise ratio (CNR) using mean absolute error and root-mean-square error. LTC showed better agreement to the ground truth strain \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${({\varvec{R}}}^{2}=0.91)$$\end{document}(R2=0.91) and ground truth strain rate \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${({\varvec{R}}}^{2}=0.85)$$\end{document}(R2=0.85) compared with agreement to ground truth for two block-matching speckle tracking algorithms (one based on sum of square difference and the other on Fourier transform correlation; strain \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${({\varvec{R}}}^{2}=0.70)$$\end{document}(R2=0.70), strain rate \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${({\varvec{R}}}^{2}=0.70)$$\end{document}(R2=0.70)). A 200% increase in strain measurement accuracy was observed compared to the conventional algorithms. Subsequently, we tested the method using a 53-subject clinical cohort (20 subjects diseased with cardiomyopathy, 33 healthy controls). Our method distinguished between normal and abnormal left ventricular function with an AUC = 0.89, a 5% improvement over the conventional GLS algorithms.

Longitudinal strain with speckle tracking echocardiography predicts electroanatomic substrate for ventricular tachycardia in non-ischemic cardiomyopathy patients

Background

Longitudinal strain (LS) derived from speckle-tracking echocardiography (STE) corresponds to regions of scar in ischemic cardiomyopathy.

Objective

We investigated if regional LS abnormalities correlate with scar location and scar burden, identified using high-density electroanatomic mapping (EAM) in nonischemic cardiomyopathy (NICM).

Methods

Fifty NICM patients with ventricular tachycardia (VT) underwent echocardiography; multilayer (endocardial, midmyocardial, and epicardial) regional LS and global LS (GLS) were evaluated prior to EAM for detection of low-voltage scar. Patients were divided into 3 groups by EAM left ventricular scar location: (1) anteroseptal (group 1, n = 20); (2) inferolateral (group 2, n = 20); and (3) epicardial scar (group 3; n = 10). We correlated (1) location of scar to regional LS and (2) regional strain and GLS to scar percentage.

Results

Regional LS abnormalities correlated with EAM scar in all groups. Segmental impaired LS and low voltage on EAM demonstrated concordance with scar in ∼75% or its border zone in 25% of segments. In groups 1 and 2, endocardial GLS showed a strong linear correlation with endocardial bipolar scar percentage (r = 0.79, 0.75 for groups 1 and 2, respectively; P < .001), whereas midmyocardial GLS correlated with unipolar scar percentage (r = 0.82, 0.78 for groups 1 and 2, respectively; P < .001). In group 3, epicardial regional LS and GLS correlated with epicardial bipolar scar percentage (r = 0.72, P < .001).

Conclusion

Regional abnormalities on LS predict scar location on EAM mapping in patients with NICM. Moreover, global and regional LS correlate with scar percentage. STE could be used as a noninvasive tool for localizing and quantifying scar prior to EAM.

Left Ventricular Strain Measurements Derived from MR Feature Tracking: A Head-to-Head Comparison of a Higher Temporal Resolution Method With a Conventional Method

BACKGROUND

Magnetic resonance feature tracking (MR-FT) is an imaging technique that quantifies both global and regional myocardial strain. Currently, conventional MR-FT provides a superior signal and contrast-to-noise ratio but has a relatively low temporal resolution. A higher temporal resolution MR-FT technique may provide improved results.

PURPOSE

To explore the impact of higher temporal resolution on left ventricular (LV) myocardial strain measurements using MR-FT.

STUDY TYPE

Prospective.

POPULATION

One hundred and fifty-three participants including five healthy subjects and patients with various cardiac diseases referred to MR for cardiac assessment.

FIELD STRENGTH

3 T, balanced steady-state free precession sequence with and without compressed sensing (temporal resolution: 10 msec and 40 msec, respectively).

ASSESSMENT

Conventional (40 msec) and higher (10 msec) temporal resolution data were acquired in all subjects during the same scanning session. Global circumferential strain (GCS), global longitudinal strain (GLS), and global radial strain (GRS) as well as peak systolic and diastolic strain rates (SRs) were measured by MR-FT and compared between the two temporal resolutions. We also performed subgroup analyses according to heart rates (HRs) and LV ejection fraction (LVEF).

STATISTICAL TESTS

Paired t-test, Wilcoxon signed-rank test, linear regression analyses, Bland-Altman plots. A P value <0.05 was considered to be statistically significant.

RESULTS

GCS and GRS were significantly higher in the 10-msec temporal resolution studies compared to the 40-msec temporal resolution studies (GCS: -13.00 ± 6.58% vs. -12.51 ± 5.76%; GRS: 21.97 ± 14.54% vs. 20.62 ± 12.52%). In the subgroup analyses, significantly higher GLS, GCS, and GRS values were obtained in subjects with LVEF ≥50%, and significantly higher GCS and GRS values were obtained in subjects with HRs <70 bpm when assessed with the 10-msec vs. the 40-msec temporal resolutions. All the peak systolic and diastolic SRs were significantly higher in the higher temporal resolution acquisitions. This was also true for all subgroups.

DATA CONCLUSIONS

Higher temporal resolution resulted in significantly higher cardiac strain and SR values using MR-FT and could be beneficial, particularly in patients with LVEF ≥50% and HR <70 bpm.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 1.

Segmentation Enhanced Elastic Image Registration for 2D Speckle Tracking Echocardiography-Performance Study In Silico

Although the two dimensional Speckle Tracking Echocardiography has gained a strong position among medical diagnostic techniques in cardiology, it still requires further developments to improve its repeatability and reliability. Few works have attempted to incorporate the left ventricle segmentation results in the process of displacements and strain estimation to improve its performance. We proposed the use of mask information as an additional penalty in the elastic image registration based displacements estimation. This approach was studied using a short axis view synthetic echocardiographic data, segmented using an active contour method. The obtained masks were distorted to a different degree, using different methods to assess the influence of the segmentation quality on the displacements and strain estimation process. The results of displacements and circumferential strain estimations show, that even though the method is dependent on the mask quality, the potential loss in accuracy due to the poor segmentation quality is much lower than the potential accuracy gain in cases where the segmentation performs well.

Quality Assurance of Segmental Strain Values Provided by Commercial 2-D Speckle Tracking Echocardiography Using in Silico Models: A Report from the EACVI-ASE Strain Standardization Task Force

The aim of this study was to determine the accuracy and reproducibility of vendor-specific regional strain values by echocardiography using in silico data. Synthetic 2-D ultrasound gray-scale images of the left ventricle (LV) were generated with knowledge of the longitudinal segmental strain values from the underlying electromechanical LV model. Four of five models mimicked transmural infarctions with systolic segmental stretching in different vascular areas. Cine loops in the three apical views were synthetically generated at four noise levels. All in silico images were repeatedly analyzed by a single investigator and some by another investigator. The absolute errors varied significantly between vendors from 3.3 ± 3.1% to 11.2 ± 5.9%. The area under the curve for the identification of segmental stretching ranged from 0.80 (confidence interval: 0.77-0.83) to 0.96 (0.95-0.98). The levels of agreement for intra-investigator variability varied between -3.0% to 2.9% and -5.2% to 4.8%, and for inter-investigator variability, between -3.6% to 3.5% and -14.5% to 8.5%. Segmental strain analysis allows the identification of areas with segmental stretching with good accuracy. However, single segmental peak-strain values are not accurate and should be interpreted with caution. Nevertheless, our results indicate the usefulness of semiquantitative strain assessment for the detection of regional dysfunction.

Prognostic superiority of global longitudinal strain beyond four-tiered ventricular hypertrophy in asymptomatic individuals

BACKGROUND

This study aims to explore the clinical correlates of myocardial deformations using speckle-tracking algorithm and to determine the prognostic utility of such measures in asymptomatic ethnic Chinese population.

METHODS

Global longitudinal (GLS), circumferential strain (GCS), and torsion were analyzed using featured tissue-tracking algorithm among 4049 symptom-free ethnic Chinese population. Hypertrophy (LVH) was classified into 4 tiers: indeterminate, dilated, thick and thick/dilated, by gender-stratified partition of end-diastolic volume index (EDVi) and LV mass/EDV0.67.

RESULTS

LVH (7.3%) showed substantially lower GLS (-20.3 ± 1.82% vs. -18.9 ± 2.08%) yet higher torsion (2.20 ± 0.90 vs. 2.39 ± 1.01, p < 0.001) than non-LVH participants. Those with thick LVH (n = 123) were more obese, had higher blood pressure and increased high-sensitivity C-reactive protein (hs-CRP); with dilated/thick LVH (n = 26) group demonstrating highest pro-brain natriuretic peptide (NT-proBNP) and worse GLS compared to indeterminate-/non-LVH groups. There were independent associations among larger EDVi, higher NT-proBNP and decreased torsion, and among greater LV mass/EDV0.67, worse GLS, greater GCS/torsion and hs-CRP. Over a median of 2.3 years (IQR: 1.2-4.8), the dilated, thick, and dilated/thick LVH categorizations were associated with higher risk of composite all-cause death and heart failure (HF) compared to non-LVH (adjusted hazard ratio [HR]: 3.65, 3.72, 6.01, respectively, all p < 0.05). Per 1% GLS reduction was independently associated with higher risk (adjusted HR: 1.31, p < 0.001) and improved risk prediction (p ≤ 0.001 by integrated discrimination improvement [IDI]: 3.5%, 95% CI: 1.5%-5.6%, and continuous net reclassification improvement [NRI]: 42.3%, 95% CI: 24.0%-60.6%) over LVH.

CONCLUSION

GLS improved risk stratification of four-tiered classification of LVH in asymptomatic ethnic Chinese.

Tissue Mitral Annular Displacement in Patients With Myocardial Infarction - Comparison With Global Longitudinal Strain

Background: Global longitudinal strain (GLS) can predict prognosis after myocardial infarction (MI). Tissue mitral annular displacement (TMAD) is another index of longitudinal left ventricular deformity, and is less dependent on image quality than GLS. We investigated the relationship between TMAD and GLS, and their ability to predict outcomes after MI. Methods and Results: GLS and TMAD were measured on echocardiograms 2 weeks after MI in 246 consecutive patients (median age 62 years, 85.7% male). TMAD was measured from apical 4- and 2-chamber views (TMAD_4ch and TMAD_2ch, respectively), and a mean value (TMAD_av) was calculated. TMAD_4ch, TMAD_2ch, and GLS were successfully measured in 240 (97.5%), 210 (85.3%) and 214 patients (87.0%), respectively. All TMAD parameters were significantly correlated with GLS (R=0.71-0.75) and left ventricular ejection fraction (LVEF; R=0.48-0.53). TMAD parameters were weakly correlated with peak creatine kinase (CK; R=0.20) and CK-MB (R=0.21-0.25). GLS and TMAD_av were significantly associated with LVEF after 6 months (R=0.48-0.53) and all-cause mortality during the follow-up period (median 1,242 days). TMAD_av discriminated patients with higher all-cause mortality when patients were divided into 3 groups, namely upper 25%, middle range, and lower 25% of TMAD_av (P=0.041, log-rank test). GLS detected high-risk patients using 15.0% as a cut-off value. Conclusions: TMAD could be a simple and reliable alternative to GLS for predicting outcomes in patients with MI.

Evaluation of strain averaging area and strain estimation errors in a spheroidal left ventricular model using synthetic image data and speckle tracking

BACKGROUND

In majority of studies on speckle tracking echocardiography (STE) the strain estimates are averaged over large areas of the left ventricle. This may impair the diagnostic capability of the STE in the case of e.g. local changes of the cardiac contractility. This work attempts to evaluate, how far one can reduce the averaging area, without sacrificing the estimation accuracy that could be important from the clinical point of view.

METHODS

Synthetic radio frequency (RF) data of a spheroidal left ventricular (LV) model were generated using FIELD II package and meshes obtained from finite element method (FEM) simulation. The apical two chamber (A2C) view and the mid parasternal short axis view (pSAXM) were simulated. The sector encompassed the entire cross-section (full view) of the LV model or its part (partial view). The wall segments obtained according to the American Heart Association (AHA17) were divided into subsegments of area decreasing down to 3 mm2. Longitudinal, circumferential and radial strain estimates, obtained using a hierarchical block-matching method, were averaged over these subsegments. Estimation accuracy was assessed using several error measures, making most use of the prediction of the maximal relative error of the strain estimate obtained using the FEM derived reference. Three limits of this predicted maximal error were studied, namely 16.7%, 33% and 66%. The smallest averaging area resulting in the strain estimation error below one of these limits was considered the smallest allowable averaging area (SAAA) of the strain estimation.

RESULTS

In all AHA17 segments, using the A2C projection, the SAAA ensuring maximal longitudinal strain estimates error below 33% was below 3 mm2, except for the segment no 17 where it was above 278 mm2. The SAAA ensuring maximal circumferential strain estimates error below 33% depended on the AHA17 segment position within the imaging sector and view type and ranged from below 3-287 mm2. The SAAA ensuring maximal radial strain estimates error below 33% obtained in the pSAXM projection was not less than 287 mm2. The SAAA values obtained using other maximal error limits differ from SAAA values observed for the 33% error limit only in limited number of cases. SAAA decreased when using maximal error limit equal to 66% in these cases. The use of the partial view (narrow sector) resulted in a decrease of the SAAA.

CONCLUSIONS

The SAAA varies strongly between strain components. In a vast part of the LV model wall in the A2C view the longitudinal strain could be estimated using SAAA below 3 mm2, which is smaller than the averaging area currently used in clinic, thus with a higher resolution. The SAAA of the circumferential strain estimation strongly depends on the position of the region of interest and the parameters of the acquisition. The SAAA of the radial strain estimation takes the highest values. The use of a narrow sector could increase diagnostic capabilities of 2D STE.

Echocardiography protocol for early detection of cardiac dysfunction in childhood cancer survivors in the multicenter DCCSS LATER 2 CARD study: Design, feasibility, and reproducibility

BACKGROUND

Cardiotoxicity is a well-known side effect after anthracyclines and chest radiotherapy in childhood cancer survivors (CCS). The DCCSS LATER 2 CARD (cardiology) study includes evaluation of echocardiographic measurements for early identification of CCS at highest risk of developing heart failure. This paper describes the design, feasibility, and reproducibility of the echocardiography protocol.

METHODS

Echocardiograms from CCS and sibling controls were prospectively obtained at the participating centers and centrally analyzed. We describe the image acquisition, measurement protocol, and software-specific considerations for myocardial strain analyses. We report the feasibility of the primary outcomes of systolic and diastolic function, as well as reproducibility analyses in 30 subjects.

RESULTS

We obtained 1,679 echocardiograms. Biplane ejection fraction (LVEF) measurement was feasible in 91% and 96% of CCS and siblings, respectively, global longitudinal strain (GLS) in 80% and 91%, global circumferential strain (GCS) in 86% and 89%, and ≥2 diastolic function parameters in 99% and 100%, right ventricle free wall strain (RVFWS) in 57% and 65%, and left atrial reservoir strain (LASr) in 72% and 79%. Intra-class correlation coefficients for inter-observer variability were 0.85 for LVEF, 0.76 for GLS, 0.70 for GCS, 0.89 for RVFWS and 0.89 for LASr. Intra-class correlation coefficients for intra-observer variability were 0.87 for LVEF, 0.82 for GLS, 0.82 for GCS, 0.85 for RVFWS and 0.79 for LASr.

CONCLUSION

The DCCSS LATER 2 CARD study includes a protocolized echocardiogram, with feasible and reproducible primary outcome measurements. This ensures high-quality outcome data for prevalence estimates and for reliable comparison of cardiac function parameters.

60-S Retrogated Compressed Sensing 2D Cine of the Heart: Sharper Borders and Accurate Quantification

Background and objective: Real-time compressed sensing cine (CS_rt) provides reliable quantification for both ventricles but may alter image quality. The aim of this study was to assess image quality and the accuracy of left (LV) and right ventricular (RV) volumes, ejection fraction and mass quantifications based on a retrogated segmented compressed sensing 2D cine sequence (CS_rg). Methods: Thirty patients were enrolled. Each patient underwent the reference retrogated segmented steady-state free precession cine sequence (SSFP_ref), the real-time CS_rt cine and the segmented retrogated prototype CS_rg sequence providing the same slices. Functional parameters quantification and image quality rating were performed on SSFP_ref and CS_rg images sets. The edge sharpness, which is an estimate of the edge spread function, was assessed for the three sequences. Results: The mean scan time was: SSFP_ref = 485.4 ± 83.3 (SD) s (95% CI: 454.3–516.5) and CS_rg = 58.3 ± 15.1 (SD) s (95% CI: 53.7–64.2) (p < 0.0001). CS_rg subjective image quality score (median: 4; range: 2–4) was higher than the one provided by CS_rt (median: 3; range: 2–4; p = 0.0008) and not different from SSFP_ref overall quality score (median: 4; range: 2–4; p = 0.31). CS_rg provided similar LV and RV functional parameters to those assessed with SSFP_ref (p > 0.05). Edge sharpness was significantly better with CS_rg (0.083 ± 0.013 (SD) pixel⁻¹; 95% CI: 0.078–0.087) than with CS_rt (0.070 ± 0.011 (SD) pixel⁻¹; 95% CI: 0.066–0.074; p = 0.0004) and not different from the reference technique (0.075 ± 0.016 (SD) pixel⁻¹; 95% CI: 0.069–0.081; p = 0.0516). Conclusions: CS_rg cine provides in one minute an accurate quantification of LV and RV functional parameters without compromising subjective and objective image quality.

Defining the optimal temporal and spatial resolution for cardiovascular magnetic resonance imaging feature tracking

BACKGROUND

Myocardial deformation analyses using cardiovascular magnetic resonance (CMR) feature tracking (CMR-FT) have incremental value in the assessment of cardiac function beyond volumetric analyses. Since guidelines do not recommend specific imaging parameters, we aimed to define optimal spatial and temporal resolutions for CMR cine images to enable reliable post-processing.

METHODS

Intra- and inter-observer reproducibility was assessed in 12 healthy subjects and 9 heart failure (HF) patients. Cine images were acquired with different temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial resolutions (high in-plane 1.5 × 1.5 mm through-plane 5 mm, standard 1.8 × 1.8 x 8mm and low 3.0 × 3.0 x 10mm). CMR-FT comprised left ventricular (LV) global and segmental longitudinal/circumferential strain (GLS/GCS) and associated systolic strain rates (SR), and right ventricular (RV) GLS.

RESULTS

Temporal but not spatial resolution did impact absolute strain and SR. Maximum absolute changes between lowest and highest temporal resolution were as follows: 1.8% and 0.3%/s for LV GLS and SR, 2.5% and 0.6%/s for GCS and SR as well as 1.4% for RV GLS. Changes of strain values occurred comparing 20 and 30 frames/cardiac cycle including LV and RV GLS and GCS (p < 0.001-0.046). In contrast, SR values (LV GLS/GCS SR) changed significantly comparing all successive temporal resolutions (p < 0.001-0.013). LV strain and SR reproducibility was not affected by either temporal or spatial resolution, whilst RV strain variability decreased with augmentation of temporal resolution.

CONCLUSION

Temporal but not spatial resolution significantly affects strain and SR in CMR-FT deformation analyses. Strain analyses require lower temporal resolution and 30 frames/cardiac cycle offer consistent strain assessments, whilst SR measurements gain from further increases in temporal resolution.

Speckle-Tracking Echocardiography with Novel Imaging Technique of Higher Frame Rate

Background: The accuracy of speckle-tracking echocardiography (STE) depends on temporal resolution. The goal of this study was to demonstrate the feasibility of relatively high frame rate (rHi-FR) (~200 fps) for STE. Methods: In this prospective study, echocardiographic images were acquired using clinical scanners on patients with normal left ventricular systolic function using rHi-FR and conventional frame rate (Reg-FR) (~50 FPS). GLS values were evaluated on apical 4-, 2- and 3-chamber images acquired in both rHi-FR and Reg-FR. Inter-observer and intra-observer variabilities were assessed in rHi-FR and Reg-FR. Results: There were 143 echocardiograms evaluated in this study. The frame rate of rHi-FR was 190 ± 25 and Reg-FR was 50 ± 3, and the heart rate was 71 ± 13. Absolute strain values measured in rHi-FR were significantly higher than those measured in Reg-FR (all p < 0.001). Inter-observer and intra-observer correlations were strong in both rHi-FR and Reg-FR. Conclusions: We demonstrated that absolute strain values were significantly higher using rHi-FR when compared with Reg-FR. It is plausible that higher temporal resolution enabled the measurement of myocardial strain at desired time point. Further investigations are necessary to evaluate the value of rHi-FR to assess myocardial strain in the setting of tachycardia.

Speckle Tracking-Derived Longitudinal Strain: Validation and Influence of Scanner Settings

Speckle tracking-based strain analysis is an evolving technique for the assessment of left ventricular function. We evaluated the influence of machine settings on global longitudinal peak systolic strain (GLPSS) values in an everyday patient population (n = 35). In each patient, the four-chamber view was recorded multiple times with different machine parameters. Ejection fraction ranged between 10% and 76% and correlated well with GLPSS (r = -0.778). GLPSS was not altered systematically by modifications of gain and frame rate. Conversely, higher transducer frequencies (mean effect: 1.102%/MHz, p < 0.001, and 0.662%/MHz, p = 0.033, for harmonic and fundamental imaging frequencies, respectively) and lower sector depth (mean effect: -0.156%/cm, p < 0.001) were associated with a slight-but statistically significant-reduction in absolute GLPSS values. Intra- and inter-observer variability exhibited satisfactory repeatability. GLPSS analysis proved to be reproducible and robust in our patient cohort if common settings for adult echocardiography were applied.

Comprehensive Assessment of Right Ventricular Function by Three-Dimensional Speckle-Tracking Echocardiography: Comparisons with Cardiac Magnetic Resonance Imaging

BACKGROUND

Three-dimensional speckle-tracking echocardiography (3D-STE) has been increasingly used to quantify right ventricular (RV) function. However, direct comparisons of 3D-STE with cardiac magnetic resonance (CMR) imaging for evaluation of RV function are limited. This study aimed to test the feasibility and accuracy of 3D-STE for the quantification of RV volumes, ejection fraction (EF), and longitudinal strain in comparison with CMR imaging and to determine whether 3D-STE for RV strain is superior to two-dimensional (2D) STE in comparison with CMR imaging.

METHODS

A total of 195 consecutive patients referred for both CMR imaging and echocardiography were studied. Right ventricular end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), RVEF, and 3D RV longitudinal strain (3D-RVLS) of the free wall by 3D-STE and 2D-RVLS of the free wall by 2D-STE, were compared with CMR measurements. Pearson correlation and Bland-Altman analyses were used to assess the intertechnique agreement.

RESULTS

Right ventricular 3D-STE was feasible in 174 patients (89%). Right ventricular volumes and EF determined by 3D-STE strongly correlated with CMR values (RVEDV, r = 0.94; RVESV, r = 0.96; RVEF, r = 0.91; all P < .001). Three-dimensional STE slightly underestimated the RV volumes and longitudinal strain and overestimated the RVEF. The 3D-RVLS values correlated better than 2D-RVLS values with CMR values (0.85 vs 0.64, P < .001) with smaller bias and narrower limits of agreement (bias: 2.0 and 2.6; limits of agreement: 8.5 and 12.5, respectively). The bias and limits of agreement for 3D-STE-obtained RVLS were increased in patients with RV dilation, RVEF < 45%, or lower frame rate compared with those with normal RV size, RVEF ≥ 45%, or higher frame rate, respectively. Right ventricular 3D-STE measurements were highly reproducible.

CONCLUSIONS

The 3D-STE measurements of RV volumes, EF, and longitudinal strain are highly feasible and reproducible, and data measured by 3D-STE correlate strongly with those determined using CMR imaging. Thus, 3D-STE may be a valid alternative to CMR imaging for the quantification of RV function in everyday clinical practice.

Transthoracic echocardiography: from guidelines for humans to cardiac ultrasound of the heart in rats

Ultrasound examination of the heart is a cornerstone of clinical evaluation of patients with established or suspected cardiovascular conditions. Advancements in ultrasound imaging technology have brought transthoracic echocardiography to preclinical murine models of cardiovascular diseases. The translational potential of cardiac ultrasound is critically important in rat models of myocardial infarction and ischemia-reperfusion injury, congestive heart failure, arterial hypertension, cardiac hypertrophy, pulmonary hypertension, right heart failure, Takotsubo cardiomyopathy, hypertrophic and dilated cardiomyopathies, developmental disorders, and metabolic syndrome. Modern echocardiographic machines capable of high-frame-rate image acquisition and fitted with high-frequency transducers allow for cardiac ultrasound in rats that yields most of the echocardiographic measurements and indices recommended by international guidelines for cardiac ultrasound in human patients. Among them are dimensions of cardiac chambers and walls, indices of systolic and diastolic cardiac function, and valvular function. In addition, measurements of cardiac dimensions and ejection fraction can be significantly improved by intravenous administration of ultrasound enhancing agents (UEAs). In this article we discuss echocardiography in rats, describe a technique for minimally invasive intravenous administration of UEAs via the saphenous vein and present a step-by-step approach to cardiac ultrasound in rats.

High prevalence of subtle systolic and diastolic dysfunction in genotype-positive phenotype-negative relatives of dilated cardiomyopathy patients

BACKGROUND

The early diagnosis of genetically determined dilated cardiomyopathy (DCM) could improve the prognosis in mutation carriers. Left ventricular global longitudinal strain (LV GLS) and peak left atrial longitudinal strain (PALS) are promising techniques for the detection of subtle systolic and diastolic dysfunction. We sought to evaluate the prevalence of subtle systolic and diastolic dysfunction by LV GLS and PALS in a cohort of genotype-positive phenotype-negative (GPFN) DCM relatives.

METHODS AND RESULTS

In this retrospective study, we analyzed echocardiograms of forty-one GPFN relatives of DCM patients. They were compared with age and sex matched healthy individuals (control group). Reduced LV GLS and PALS were defined as >18% and <23.1%, respectively. GPFN relatives (37 ± 14 years, 48.8% male) and controls were similar according to standard echocardiographic measurements. Conversely, LV GLS was -18.8 ± 2.7% in the GPFN group vs. -24.0 ± 1.8% in the control group (p < 0.001). Twenty subjects (48.8%) in the GPFN group and no subjects in the control group had a reduced LV GLS. PALS was 29.2 ± 6.7% in the GPFN group vs. 40.8 ± 8.5% in the control group (p < 0.001). Seven subjects (18.4%) in the GPFN group and one (2%) in the control group had a reduced PALS. A cohort of 17 genotype-negative phenotype-negative relatives showed higher values of LV GLS compared to GPFN.

CONCLUSIONS

Despite standard echocardiographic parameters are within the normal range, LV GLS and PALS are lower in GPFN relatives of DCM patients when compared to healthy individuals, suggesting a consistent proportion of subtle systolic and diastolic dysfunction in this population.

Strain Curve Classification Using Supervised Machine Learning Algorithm with Physiologic Constraints

Speckle tracking echocardiography (STE) enables quantification of myocardial deformation by a generation of spatiotemporal strain curves or time-strain curves (TSCs). Currently, only assessment of peak global longitudinal strain is employed in clinical practice because of the uncertainty in the accuracy of STE. We describe a supervised machine learning, physiologically constrained, fully automatic algorithm, trained with labeled data, for classification of TSCs into physiologic or artifactual classes. The data set of 415 healthy patients, with three cine loops per patient, corresponding to the three standard 2-D longitudinal views, was processed using a previously published, in-house STE software termed K-SAD. We report an accuracy of 86.4% for classifying TSCs as physiologic, artifactual and undetermined curves. The positive predictive value for a physiologic strain curve is 89%. This is as a necessary step for a similar separation of pathologic conditions, to allow full utilization of the temporal information concealed in layer-specific segmental TSCs.

Fetal Speckle-Tracking: Impact of Angle of Insonation and Frame Rate on Global Longitudinal Strain

BACKGROUND

There is a growing body of research on fetal speckle-tracking echocardiography because it is considered to be an angle-independent modality. The primary aim of this study was to investigate whether angle of insonation and acquisition frame rate (FR) influence left ventricular endocardial global longitudinal peak strain (GLS) in the fetus.

METHODS

Four-chamber views of 122 healthy fetuses were studied at three different angles of insonation (apex up/down, apex oblique, and apex perpendicular) at high and low acoustic FRs. GLS was calculated, and a linear mixed-model analysis was used for analysis. Six hundred fifty-six fetal echocardiographic clips were analyzed (288 in the second trimester, at a median gestation of 21 weeks [interquartile range (IQR), 1 week], and 368 in the third trimester, at a median gestation of 36 weeks [IQR, 2 weeks]).

RESULTS

Angle of insonation and FRs were significant determinants of GLS. Ventricular septum perpendicular to the ultrasound beam was associated with higher (more negative) GLS compared with apex up/down (at high FR: -21.8% vs -19.7%, P < .001; at low FR: -24.1% vs -21.4%, P < .001). Higher frames per second (FPS; median 149 FPS [IQR, 33 FPS] = 61 frames per cycle [FPC] [IQR, 17 FPC]) compared with lower FPS (median 51 FPS [IQR, 15 FPS] = 22 FPC [IQR, 7 FPC]) at the same insonation angle resulted in lower GLS (apex up/down: -19.7% vs -21.4%, P < .001; apex oblique: -21.2% vs -22.7%, P < .001; apex perpendicular: -21.8% vs -24.1%, P < .001).

CONCLUSIONS

The present findings show that insonation angle and FR influence GLS significantly. These factors need to be considered when comparing studies with different acquisition protocols, when establishing normative values, and when interpreting pathology. Speckle-tracking echocardiography cannot be considered an angle-independent modality during fetal life.

Quantification of left atrial wall motion in healthy horses using two-dimensional speckle tracking

INTRODUCTION

The mechanical function of the left atrium (LA) plays a pivotal role in modulation of left ventricular filling. Assessment of LA function might be a clinically useful prognostic tool for horses with mitral regurgitation or atrial fibrillation. However, the most accurate, reliable, and clinically useful methods to assess LA myocardial function are yet to be determined. The objective of this study was to describe the methods for quantification of LA wall motion using two-dimensional speckle tracking (2DST) echocardiography in healthy Warmblood horses to quantify measurement variability, to calculate reference intervals for 2DST variables, and to investigate their relationship to sex, age, body weight, and heart rate.

ANIMALS, MATERIALS, AND METHODS

Twenty-six healthy Warmblood horses were included. 2DST analyses of LA wall motion were performed on digitally stored cine-loop recordings of a standardized right-parasternal four-chamber view focusing on the LA. Longitudinal strain, longitudinal strain rate, and time to peak LA contraction were measured to characterize LA contractile, reservoir, and conduit function. Intraobserver and interobserver measurement variability was quantified, and reference intervals were calculated.

RESULTS

The coefficient of variation for intraobserver and interobserver measurement variability ranged between 2.0-11.1% and 5.1-15.4%, respectively, for global strain, strain rate, and time to peak LA contraction. Reference intervals for healthy Warmblood horses were reported.

CONCLUSION

This study shows that 2DST is a feasible and reliable method to quantify LA wall motion throughout the cardiac cycle in healthy Warmblood horses. Further studies are required to establish the clinical value of 2DST for assessment of LA function.

Value of myocardial work for assessment of myocardial adaptation to increased afterload in patients with high blood pressure at peak exercise

Non-invasive myocardial work (MW) indices are superior to global longitudinal strain (GLS) to assess left ventricular (LV) mechanics in situations where afterload is abnormally high. The rotational motion of the apex provides an accurate index of LV contractility. To date, there are no data about MW values during stress echocardiography (SE), particularly for the apex. Our study aims at assessing MW indices at peak exercise to better understand LV mechanics in patients with high peak systolic blood pressure (SBP). A total of 81 patients without structural or ischemic heart disease referred for SE between January and June 2019 were included. BP measurements, GLS and MW indices were performed at rest and peak exercise. In order to quantify the role of the apex, apical work fraction (AWF) was also calculated and further stratified by peak SBP. A peak SBP > 180 mmHg was considered abnormally high. There were 36 (44%) patients who had peak SBP > 180 mmHg. They showed similar resting GLS and MW values when compared to control. However, peak stress global work index, constructive work and wasted work (GWW) increased significantly (P-value < 0.05), with a relatively constant global work efficiency. In the multivariate analysis, peak SBP > 180 mmHg was associated with threefold increased odds of abnormal peak GWW > 96.5 mmHg% (median value) (odds ratio 3.0, P-value 0.003). Apical work increased significantly when stratified by peak SBP (P-value 0.003) and AWF increased from 33 ± 3% to 37 ± 3% (rest-stress), P-value < 0.0001, but remained constant when stratified by peak SBP. Our analysis provides new data on MW indices at peak stress, particularly for patients with abnormal peak SBP response, and supports the role and the contribution of the apex to MW.

A left ventricular phantom for 3D echocardiographic twist measurements

Traditional two-dimensional (2D) ultrasound speckle tracking echocardiography (STE) studies have shown a wide range of twist values, also for normal hearts, which is due to the limitations of short-axis 2D ultrasound. The same limitations do not apply to three-dimensional (3D) ultrasound, and several studies have shown 3D ultrasound to be superior to 2D ultrasound, which is unreliable for measuring twist. The aim of this study was to develop a left ventricular twisting phantom and to evaluate the accuracy of 3D STE twist measurements using different acquisition methods and volume rates (VR). This phantom was not intended to simulate a heart, but to function as a medium for ultrasound deformation measurement. The phantom was made of polyvinyl alcohol (PVA) and casted using 3D printed molds. Twist was obtained by making the phantom consist of two PVA layers with different elastic properties in a spiral pattern. This gave increased apical rotation with increased stroke volume in a mock circulation. To test the accuracy of 3D STE twist, both single-beat, as well as two, four and six multi-beat acquisitions, were recorded and compared against twist from implanted sonomicrometry crystals. A custom-made software was developed to calculate twist from sonomicrometry. The phantom gave sonomicrometer twist values from 2.0° to 13.8° depending on the stroke volume. STE software tracked the phantom wall well at several combinations of temporal and spatial resolution. Agreement between the two twist methods was best for multi-beat acquisitions in the range of 14.4–30.4 volumes per second (VPS), while poorer for single-beat and higher multi-beat VRs. Smallest offset was obtained at six-beat multi-beat at 17.1 VPS and 30.4 VPS. The phantom proved to be a useful tool for simulating cardiac twist and gave different twist at different stroke volumes. Best agreement with the sonomicrometer reference method was obtained at good spatial resolution (high beam density) and a relatively low VR. 3D STE twist values showed better agreement with sonomicrometry for most multi-beat recordings compared with single-beat recordings.

Ultrasound-based estimation of remaining cardiac function in LVAD-supported ex vivo hearts

Left ventricular assist devices (LVAD) provide cardiac support to patients with advanced heart failure. Methods that can directly measure remaining LV function following device implantation do not currently exist. Previous studies have shown that a combination of loading (LV pressure) and deformation (strain) measurements enables quantitation of myocardial work. We investigated the use of ultrasound (US) strain imaging and pressure–strain loop analysis in LVAD‐supported hearts under different hemodynamic and pump unloading conditions, with the aim of determining LV function with and without LVAD support. Ex vivo porcine hearts (n = 4) were implanted with LVADs and attached to a mock circulatory loop. Measurements were performed at hemodynamically defined “heart conditions” as the hearts deteriorated from baseline. Hemodynamic (including LV pressure) and radio‐frequency US data were acquired during a pump‐ramp protocol at speeds from 0 (with no pump outflow) to 10 000 revolutions per minute (rpm). Regional circumferential (ε_circ) and radial (ε_rad) strains were estimated over each heart cycle. Regional ventricular dyssynchrony was quantitated through time‐to‐peak strain. Mean change in LV pulse pressure and ε_circ between 0 and 10 krpm were −21.8 mm Hg and −7.24% in the first condition; in the final condition −46.8 mm Hg and −19.2%, respectively. ε_rad was not indicative of changes in pump speed or heart condition. Pressure–strain loops showed a degradation in the LV function and an increased influence of LV unloading: loop area reduced by 90% between 0 krpm in the first heart condition and 10 krpm in the last condition. High pump speeds and degraded condition led to increased dyssynchrony between the septal and lateral LV walls. Functional measurement of the LV while undergoing LVAD support is possible by using US strain imaging and pressure–strain loops. This can provide important information about remaining pump function. Use of novel LV pressure estimation or measurement techniques would be required for any future use in LVAD patients.

Left Ventricular Strain and Strain Rate during Submaximal Semisupine Bicycle Exercise Stress Echocardiography in Healthy Adolescents and Young Adults: Systematic Protocol and Reference Values

OBJECTIVE

Combining stress echocardiography with strain analysis is a promising approach for early detection of subclinical cardiac dysfunction not apparent at rest. Data on normal myocardial strain and strain rate (SR) response to exercise in adolescents and young adults are contradictory and limited. The aim of this study was to propose a standardized protocol for semisupine bicycle stress echocardiography and to provide corresponding reference values of left ventricular (LV) two-dimensional speckle-tracking echocardiography (2D STE) strain and SR in adolescents and young adults.

METHODS

Fifty healthy adolescents and young adults (mean age, 17.8 ± 3.2 years, 44% female) were prospectively assessed. Images were acquired at rest, low stress, submaximal stress, and during recovery. Optimal image quality for offline strain analysis was pursued, and image quality was rated. Global longitudinal strain and SR from apical four-/two-/three-chamber views and short-axis circumferential strain and SR were analyzed using vendor-independent software. Interobserver variability was assessed.

RESULTS

Strain and SR increased during progressive exercise stress. Mean LV global longitudinal strain was -20.4% ± 1.3%, SR -1.1 ± 0.15/sec at rest (heart rate, 79.4 ± 12.0 beats/minute), increasing to -22.6% ± 1.6% and -1.5 ± 0.16/sec at low stress level (heart rate, 117.1 ± 8.7 beats/minute) and -23.7% ± 1.1% and -1.9 ± 0.29/sec at submaximal stress level (heart rate, 154.2 ± 7.0 beats/minute), respectively, returning to -20.6% ± 1.4% and -1.2 ± 0.16/sec postexercise (heart rate, 90.1 ± 9.4 beats/minute). Restriction on submaximal stress level ensured adequate image quality for 2D STE strain analysis. Interobserver variability for strain was acceptable even during submaximal stress.

CONCLUSIONS

This study provides a systematic, standardized protocol and corresponding reference data for 2D LV STE-derived strain and SR during semisupine bicycle exercise testing in adolescents and young adults. According to our results, global longitudinal strain and SR appear to be the most comprehensible parameters for cross-sectional studies.

Strain analysis reveals subtle systolic dysfunction in confirmed and suspected myocarditis with normal LVEF. A cardiac magnetic resonance study

AIMS

Lake Louise Criteria (LLC) are time-dependent and some acute myocarditis (AM) with preserved left ventricular ejection fraction (LVEF) could be missed, due to the limited accessibility of Cardiac Magnetic Resonance (CMR). We aimed to assess the potential value of cardiac strain measured by feature tracking (FT) imaging in this population.

METHODS AND RESULTS

Eighty-three patients with clinically suspected AM and normal LVEF were divided into 39 "confirmed AM" (positive LLC) and 44 "suspected AM" (negative LLC). An age and gender-matched sample of 42 normal subjects underwent CMR. In all groups, FT-derived biventricular strains and STE- global longitudinal strain (GLS) were assessed, being regularly measurable. Strain values < 5th percentile of the control group were considered abnormal. "Suspected" and "confirmed" AM were similar, except for medium time of CMR evaluation (5.2 vs 1 months from presentation, respectively; p = 0.004). Compared to healthy controls, both "suspected" and "confirmed" AM showed significantly impaired strain values. LV-global circumferential strain (GCS), right ventricular GCS and LV-GLS were abnormal in 15.4% and 15.9%, 20.5% and 15.9%, 7.7% and 9.1% in "confirmed" and "suspected" AM, respectively. STE analysis confirmed the results on LV-GLS, however a weak correlation emerged between STE and CMR-FT LV-GLS (p = 0.08).

CONCLUSIONS

Compared to STE, CMR-FT analysis provided a more comprehensive and complementary biventricular strain evaluation that resulted similar in "confirmed" and "suspected" AM with normal LVEF. Conversely, mostly biventricular GCS was significantly reduced in up to 20% of patients, compared to healthy controls.

Reproducibility and Intervendor Agreement of Left Ventricular Global Systolic Strain in Children Using a Layer-Specific Analysis

BACKGROUND

Speckle-tracking strain analysis provides additive data to the assessment of pediatric and congenital heart disease; however, the variety of strain analysis software platforms by different vendors and the lack of data on intervendor strain agreement in children have limited its utility. The purpose of this study is to evaluate the intervendor agreement of strain on two commonly used analysis platforms in pediatrics by layer of myocardium and data compression.

METHODS

This prospective study analyzed two-dimensional speckle-tracking strain on two software platforms in 53 children with normal cardiac segmental anatomy and varying function. Three standard apical views and one parasternal short-axis view were exported at their acquired frame rates to workstations with GE EchoPAC and TomTec software and then also to TomTec at compressed frame rates. Both software platforms had been updated with European Association of Cardiovascular Imaging/American Society of Echocardiography Task Force recommendations for left ventricular (LV) global strain. Intravendor and intervendor agreement between layer-specific comparisons were assessed using Bland-Altman analysis (limits of agreement and bias) and intraclass correlation coefficients.

RESULTS

This study included subjects with normal LV function (n = 38) and cardiomyopathy (n = 15) with an age range of 1 month to 18 years. Intertechnique agreement by default vendor myocardial layer (GE mid-TomTec endocardial layer) was robust for both global longitudinal (GLS) and circumferential strain (GCS; higher for GLS than GCS). Intravendor (inter- and interreader) agreement was slightly higher than intervendor. Only small differences in intraclass correlation coefficients were present between various myocardial layers and acquired versus compressed TomTec data with narrow limits of agreement and small bias except in certain subgroup comparisons.

CONCLUSIONS

Comparison of LV GLS and GCS between two commonly used software platforms after European Association of Cardiovascular Imaging/American Society of Echocardiography Industry Task Force recommendations demonstrated good to excellent agreement in pediatrics, regardless of the layer of analysis or the image format, although some degree of variability remains between vendor platforms. Overall, GLS agreement was more robust than GCS, and this difference is exaggerated in specific subanalyses. These data suggest that comparisons of strain values obtained on these two vendors will be reasonable, but caution should be used when the indication is the detection of small differences between serial echocardiograms.