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Background: The slope of the relationship between segmental PreS and total systolic shortening (S) has been proposed as a non-invasive index of left ventricular contractility. The aim of this study was to correlate this novel parameter to invasive gold standard measurements of contractility and to investigate how it is influenced by afterload., Methods: In domestic pigs, afterload was increased by either balloon inflation in the aorta or by administration of phenylephrine while contractility was increased by dobutamine infusion. During all interventions, left ventricular pressure-volume measurements and trans-diaphragmatic two-dimensional echocardiographic images were acquired. The PreS-S slope was constructed from 18 segmental strain curves obtained by speckle tracking analysis and compared to the slope of the end systolic PV relationship (Emax) and the pre-load recruitable stroke work (PRSW)., Results: Sixteen datasets of increased contractility and afterload were analyzed. During dobutamine infusion, the LV volumes decreased (p<0.05) while ejection fraction increased (p<0.05). Emax, PRSW and the slope of the intra-ventricular PreS-S relation increased significantly during dobutamine infusion. Afterload increase led to increase in systolic blood pressure (105±16mmHg vs. 138±25mmHg; p<0.01) and decrease of LV stroke volume and ejection fraction (p<0.01). The PreS-S slope was not influenced by loading conditions in concordance with the PRSW findings. The absolute values of the PreS-S slope did not correlate with Emax or PRSW. However, the change of the PreS-S slope in relation with different interventions demonstrated good correlation with changes in PRSW or Emax, (r = 0.66, p<0.05 and r = 0.69, p<0.05)., Conclusions: The slope of the PreS-S relationship is sensitive to changes in inotropy and is less load-dependent than conventional non-invasive parameters of left ventricular function. The magnitude of the change of this slope correlates well with changes in invasive contractility measurements making it an attractive parameter to assess contractile reserve or contractile changes during longitudinal follow-up of patients., Competing Interests: The authors have declared that no competing interests exist.

Speckle tracking echocardiography offers a unique opportunity to evaluate myocardial function, and global longitudinal strain (GLS) is currently recommended as a measurement of global left ventricular function. To facilitate clinical applicability of the method, collective efforts have been made to standardise strain measurements and to raise awareness of the potential sources of variability. The purpose of this review is to familiarise the reader with the most common sources of variability of longitudinal strain measurements and detail the possible measures to increase the accuracy and reproducibility of strain parameters.

Background: Despite standardization efforts, vendors still use information from different myocardial layers to calculate global longitudinal strain (GLS). Little is known about potential advantages or disadvantages of using these different layers in clinical practice. The authors therefore investigated the reproducibility and accuracy of GLS measurements from different myocardial layers., Methods: Sixty-three subjects were prospectively enrolled, in whom the intervendor bias and test-retest variability of endocardial GLS (E-GLS) and midwall GLS (M-GLS) were calculated, using software packages from five vendors that allow layer-specific GLS calculation (GE, Hitachi, Siemens, Toshiba, and TomTec). The impact of tracking quality and the interdependence of strain values from different layers were assessed by comparing test-retest errors between layers., Results: For both E-GLS and M-GLS, significant bias was found among vendors. Relative test-retest variability of E-GLS values differed significantly among vendors, whereas M-GLS showed no significant difference (range, 5.4%-9.5% [P = .032] and 7.0%-11.2% [P = .200], respectively). Within-vendor test-retest variability was similar between E-GLS and M-GLS for all but one vendor. Absolute test-retest errors were highly correlated between E-GLS and M-GLS for all vendors., Conclusions: E-GLS and M-GLS measurements showed no relevant differences in robustness among vendors, although intervendor bias was higher for M-GLS compared with E-GLS. These data provide no technical argument in favor of a certain myocardial layer for global left ventricular functional assessment. Currently, the choice of which layer to use should therefore be based on the available clinical evidence in the literature., (Copyright © 2017 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to compare the accuracy of vendor-specific and independent strain analysis tools to detect regional myocardial function abnormality in a clinical setting., Background: Speckle tracking echocardiography has been considered a promising tool for the quantitative assessment of regional myocardial function. However, the potential differences among speckle tracking software with regard to their accuracy in identifying regional abnormality has not been studied extensively., Methods: Sixty-three subjects (5 healthy volunteers and 58 patients) were examined with 7 different ultrasound machines during 5 days. All patients had experienced a previous myocardial infarction, which was characterized by cardiac magnetic resonance with late gadolinium enhancement. Segmental peak systolic (PS), end-systolic (ES) and post-systolic strain (PSS) measurements were obtained with 6 vendor-specific software tools and 2 independent strain analysis tools. Strain parameters were compared between fully scarred and scar-free segments. Receiver-operating characteristic curves testing the ability of strain parameters and derived indexes to discriminate between these segments were compared among vendors., Results: The average strain values calculated for normal segments ranged from -15.1% to -20.7% for PS, -14.9% to -20.6% for ES, and -16.1% to -21.4% for PSS. Significantly lower values of strain (p < 0.05) were found in segments with transmural scar by all vendors, with values ranging from -7.4% to -11.1% for PS, -7.7% to -10.8% for ES, and -10.5% to -14.3% for PSS. Accuracy in identifying transmural scar ranged from acceptable to excellent (area under the curve 0.74 to 0.83 for PS and ES and 0.70 to 0.78 for PSS). Significant differences were found among vendors (p < 0.05). All vendors had a significantly lower accuracy to detect scars in the basal segments compared with scars in the apex (p < 0.05)., Conclusions: The accuracy of identifying regional abnormality differs significantly among vendors., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: In this study, we compared left ventricular (LV) segmental strain measurements obtained with different ultrasound machines and post-processing software packages., Background: Global longitudinal strain (GLS) has proven to be a reproducible and valuable tool in clinical practice. Data about the reproducibility and intervendor differences of segmental strain measurements, however, are missing., Methods: We included 63 volunteers with cardiac magnetic resonance-proven infarct scar with segmental LV function ranging from normal to severely impaired. Each subject was examined within 2 h by a single expert sonographer with machines from multiple vendors. All 3 apical views were acquired twice to determine the test-retest and the intervendor variability. Segmental longitudinal peak systolic, end-systolic, and post-systolic strain were measured using 7 vendor-specific systems (Hitachi, Tokyo, Japan; Esaote, Florence, Italy; GE Vingmed Ultrasound, Horten, Norway; Philips, Andover, Massachusetts; Samsung, Seoul, South Korea; Siemens, Mountain View, California; and Toshiba, Otawara, Japan) and 2 independent software packages (Epsilon, Ann Arbor, Michigan; and TOMTEC, Unterschleissheim, Germany) and compared among vendors., Results: Image quality and tracking feasibility differed among vendors (analysis of variance, p < 0.05). The absolute test-retest difference ranged from 2.5% to 4.9% for peak systolic, 2.6% to 5.0% for end-systolic, and 2.5% to 5.0% for post-systolic strain. The average segmental strain values varied significantly between vendors (up to 4.5%). Segmental strain parameters from each vendor correlated well with the mean of all vendors (r 2 range 0.58 to 0.81) but showed very different ranges of values. Bias and limits of agreement were up to -4.6 ± 7.5%., Conclusions: In contrast to GLS, LV segmental longitudinal strain measurements have a higher variability on top of the known intervendor bias. The fidelity of different software to follow segmental function varies considerably. We conclude that single segmental strain values should be used with caution in the clinic. Segmental strain pattern analysis might be a more robust alternative., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

The aim of this study was to analyze the whole temporal profiles of the segmental deformation curves of the left ventricle (LV) and describe their interrelations to obtain more detailed information concerning global LV function in order to be able to identify abnormal changes in LV mechanics. The temporal characteristics of the segmental LV deformation curves were compactly described using an efficient decomposition into major patterns of variation through a statistical method, called Principal Component Analysis (PCA). In order to describe the spatial relations between the segmental traces, the PCA-derived temporal features of all LV segments were concatenated. The obtained set of features was then used to build an automatic classification system. The proposed methodology was applied to a group of 60 MRI-delayed enhancement confirmed infarct patients and 60 controls in order to detect myocardial infarction. An average classification accuracy of 87% with corresponding sensitivity and specificity rates of 89% and 85%, respectively was obtained by the proposed methodology applied on the strain rate curves. This classification performance was better than that obtained with the same methodology applied on the strain curves, reading of two expert cardiologists as well as comparative classification systems using only the spatial distribution of the end-systolic strain and peak-systolic strain rate values. This study shows the potential of machine learning in the field of cardiac deformation imaging where an efficient representation of the spatio-temporal characteristics of the segmental deformation curves allowed automatic classification of infarcted from control hearts with high accuracy.

Background: A plethora of echo parameters has been suggested for distinguishing cardiac amyloidosis (CA) from other causes of myocardial thickening with, however, scarce data on their head-to-head comparison. This study aimed at comparing the diagnostic accuracy of various deformation and conventional echo parameters in differentiating CA from other hypertrophic substrates, especially in the gray zone of mild hypertrophy (maximum wall thickness ≤16 mm) or normal ejection fraction (EF)., Methods and Results: We included 100 subjects, of which 40 were patients with newly diagnosed, biopsy-proven CA (65.5±10.8 years, 65% male, 62.5% amyloidosis light chain [AL] type), 40 patients with hypertrophic cardiomyopathy matched for demographics and maximum wall thickness (60.1±14.8 years, 85% male), and 20 hypertensives with prominent myocardial remodeling. Quantifiable conventional morphological and functional parameters along with multidimensional strain and strain-derived ratios indices, previously suggested to diagnose CA, were analyzed. EF global longitudinal strain ratio showed the best performance to discriminate CA (area under the curve, 0.95; 95% confidence intervals, 0.89-0.98; P <0.00005). Traditional echo indices showed overall low sensitivities and high specificities (among them myocardial contraction fraction ratio had the highest area under the curve, 0.80; 95% confidence intervals, 0.7-0.87; P <0.0001). In the challenging subgroups (maximum wall thickness ≤16 mm and EF>55%), EF global longitudinal strain ratio remained the best predicting parameter of CA diagnosis (multiple logistic regression models P <0.00005 and P =0.0002, respectively) independent of the CA type., Conclusions: Our study demonstrated that in patients with thickened hearts, EF global longitudinal strain ratio has the best accuracy in detecting CA, even among the most "challenging" patient subgroups as those with mild hypertrophy and normal EF., (© 2017 American Heart Association, Inc.)