Layer-specific assessment of left ventricular function by utilizing wavelet de-noising: a validation study

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.

New Myocardial Deformation by 2D Multi-layer Speckle-Tracking Analysis in Healthy Patients: Normal Reference Values and Their Physiologic Determinants

There are limited data regarding intrinsic changes of the left (LV) and right ventricular (RV) deformation assessed layer-by-layer. We designed a prospective multi-centric study, using a new multi-layer 2D-speckle-tracking-echo (MSTE). We investigated the impact of different physiologic parameters on layer-specific LV/RV myocardial deformation and synchrony, in a large group of healty subjects. 151 subjects were feasible for MSTE, divided in 4 groups: <40 yrs, 41 to 50 yrs, 51 to 60, and >61 yrs. We found a significant higher LV dyssynchrony index with age. In all groups, an endo-epicardial gradient was present in longitudinal LV/RV and circumferential deformation, with higher values in endocardial layer (p<0.001). There were no differences in deformation with age in all layers. We provided normal reference values for a new index of LV dyssynchrony, and also for RV longitudinal, LV circumferential and longitudinal layer-specific deformation, which can be further used when assessing subclinical dysfunction in myocardial diseases.

Early assessment of the left ventricular function by epirubicin-induced cardiotoxicity in postoperative breast cancer patients

OBJECTIVE

Epirubicin (Epi) is a potent and effective drug for many malignant cancers with serious cardiotoxicity. Therefore, layer-specific two-dimensional speckle tracking echocardiography (2D-STE) was used to evaluate the longitudinal and circumferential systolic function of the left ventricular for the early detection of cardiotoxicity in this retrospective work.

METHODS

Overall, 130 female patients with postoperative breast cancer who did not receive radiotherapy were classified into three groups: Group A (control group, n = 40) without any chemotherapy; Group B (n = 44) administered Epi at 180 ~ 240 mg/m² ; and Group C (n = 46) administered Epi at ≥360 mg/m² . Peak and global systolic longitudinal strains (GLS) in the total and endocardium, mid-myocardium, and epicardium were measured and calculated from apical four-chamber, apical two-chamber, and left ventricular long-axis views, respectively. Peak and global circumferential strains (GCS) in the total and endocardium, mid-myocardium, and epicardium were measured and calculated from mitral annulus, papillary muscle, and apical levels of the short-axis view, respectively.

RESULTS

The total GLS and GLS of the endocardium in every view were significantly reduced in group C compared with both groups A and B (P < .05), but there was no significant difference between groups A and B (P > .05). The GLS of the epicardium and mid-myocardium in groups B and C were not significantly reduced (P > .05). There were no significant differences in the total GCS and layer-specific GCS of endocardium, mid-myocardium, and epicardium among the three groups (P > .05).

CONCLUSIONS

Left ventricular longitudinal systolic dysfunction was detected. Moreover, an impaired endocardium was also detected in an early assessment by layer-specific 2DSTE.

Intra-procedural determination of viability by myocardial deformation imaging: a randomized prospective study in the cardiac catheter laboratory

BACKGROUND

The benefit of revascularization for functional recovery depends on the presence of viable myocardial tissue.

OBJECTIVE

Myocardial deformation imaging allows determination of myocardial viability.

METHODS

In a first approach, we assessed the optimal cutoff value to determine preserved viability by layer-specific echocardiographic myocardial deformation imaging at rest and low-dose dobutamine (DSE) echocardiography: regional endocardial circumferential strain (eCS) <-19% at rest was as accurate as eCS at DSE. In a main study, 123 patients (66% men, age 59 ± 6 years) with relevant coronary stenoses and corresponding severe regional myocardial dysfunction were included and randomized in 2 groups after coronary angiography: group A: intra-procedural myocardial deformation imaging in the cardiac catheter laboratory (CLab), determination of myocardial viability by regional eCS <-19%, in case of positive viability immediate coronary intervention in the same session. Group B: two-step determination of myocardial viability by cardiovascular magnetic resonance (CMR), in case of positive viability coronary intervention. After 18 months follow-up an analysis of the endpoints regarding cardiovascular events, left ventricular (LV) function, and comparison of cost was performed.

RESULTS

Group A (N = 61) and group B (N = 62) showed no differences concerning localization of the coronary stenosis, comorbidities, or medical therapy. Cardiovascular events at 18-month follow-up were as follows: group A 13% (N = 10) vs. group B 14% (N = 9, p = 0.288); improvement of LV function: group A: +7 ± 2% vs. group B: +7 ± 3%, p = 0.963; costs: group A: 3096 Dollar vs. group B: 6043 Dollar, p < 0.001.

CONCLUSION

Intra-procedural determination of myocardial viability by myocardial deformation imaging in the CLab is feasible, safe, and cost effective and may become an emerging alternative to the current practice of two-stage viability diagnostics.

Layer-specific analysis of myocardial deformation for assessment of infarct transmurality: comparison of strain-encoded cardiovascular magnetic resonance with 2D speckle tracking echocardiography

AIMS

Separate analysis of endocardial and epicardial myocardial layer deformation has become possible using strain-encoded cardiovascular magnetic resonance (SENC) and 2D-dimensional speckle tracking echocardiography (Echo). This study evaluated and compared both modalities for the assessment of infarct transmurality as defined by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR).

METHODS AND RESULTS

In 29 patients (age 62.4 ± 11.7 years, 23 male) with ischaemic cardiomyopathy, SENC using 1.5 T CMR and Echo were performed. Peak circumferential systolic strain of the endocardial and the epicardial layer of 304 myocardial segments was assessed by SENC and by Echo. The segmental transmurality of myocardial infarction was determined as relative amount of LGE (0%: no infarction; 1-50%: non-transmural infarction; 51-100%: transmural infarction). Endocardial and epicardial strain defined by SENC and by Echo differed significantly between segments of different infarct transmurality determined by CMR. Endocardial layer circumferential strain analysis by Echo and by SENC allowed distinction of segments with non-transmural infarction from non-infarcted segments with similar accuracy [area under the curve (AUC) 0.699 vs. 0.649, respectively, P = 0.239]. Epicardial layer circumferential strain analysis by Echo and by SENC allowed distinction of transmural from non-transmural myocardial infarction defined by LGE CMR with similar accuracy (AUC 0.721 vs. 0.664, respectively, P = 0.401). Endocardial strain by SENC correlated moderately with endocardial strain by Echo (r = 0.50; standard error of estimate = 5.2%).

CONCLUSION

Layer-specific analysis of myocardial deformation by Echo and by SENC allows discrimination between different transmurality categories of myocardial infarction with similar accuracy. However, accuracy of both methods is non-optimal, indicating that further tools for improvement should be evaluated in the future.

Quantitative analysis of endocardial and epicardial left ventricular myocardial deformation-comparison of strain-encoded cardiac magnetic resonance imaging with two-dimensional speckle-tracking echocardiography

BACKGROUND

Quantitative analysis of segmental myocardial deformation of different myocardial layers has become possible using strain-encoded cardiac magnetic resonance imaging (SENC) and speckle-tracking echocardiography (STE). We evaluated and compared the quantitative analysis of myocardial deformation using SENC and STE.

METHODS

In 44 patients (age 61 ± 13 years, 34 men), SENC by cardiac magnetic resonance imaging using a 1.5-Tesla whole-body scanner and two-dimensional STE were performed prospectively. Quantitative layer-specific analysis of segmental left ventricular function was performed to determine the peak circumferential and peak longitudinal systolic strain values using SENC and STE of an endocardial and epicardial myocardial layer. In addition, segmental function was defined as normokinetic, hypokinetic, or akinetic by visual analysis of the magnetic resonance imaging cine sequences.

RESULTS

The endocardial and epicardial strain defined by SENC or STE differed significantly between the visually defined segmental function states. The correlation of the peak circumferential endocardial strain by SENC versus STE (intraclass correlation coefficient [ICC] 0.493, 95% CI 0.358-0.597) tended to be better than the correlation of the circumferential epicardial strain using both methods (ICC 0.321, 95% CI 0.238-0.399). The correlation of the peak longitudinal endocardial strain by SENC and STE was similar (ICC 0.472, 95% CI 0.398-0.541), in contrast to the longitudinal epicardial strain analysis by both techniques (ICC 0.554, 95% CI 0.417-0.655). Circumferential strain analysis by STE allowed better distinction of the hypokinetic or akinetic segments from the normokinetic segments than did the circumferential strain analysis by SENC of the endocardial layer (area under the receiver operating characteristic curve [AUC ROC] 0.946 vs 0.884; P < .001) or epicardial layer (AUC ROC 0.884 vs 0.782; P < .001). Longitudinal strain analysis using STE and SENC of the endocardial layer (AUC ROC 0.851 vs 0.839; P = .5838) and epicardial layer (AUC ROC 0.849 vs 0.833; P = .4321) had similar diagnostic value for identifying the presence of hypokinetic and akinetic segments.

CONCLUSIONS

Quantitative analysis of segmental deformation by SENC and STE allowed accurate distinction of myocardial segments with different functional states. Circumferential endocardial strain analysis by STE allowed the best distinction of segments with impaired function from the normokinetic segments.

Layer-specific strain analysis: investigation of regional deformations in a rat model of acute versus chronic myocardial infarction

Myocardial infarction (MI) injury extends from the endocardium toward the epicardium. This phenomenon should be taken into consideration in the detection of MI. To study the extent of damage at different stages of MI, we hypothesized that measurement of layer-specific strain will allow better delineation of the MI extent than total wall thickness strain at acute stages but not at chronic stages, when fibrosis and remodeling have already occurred. After baseline echocardiography scans had been obtained, 24 rats underwent occlusion of the left anterior descending coronary artery for 30 min followed by reperfusion. Thirteen rats were rescanned at 24 h post-MI and eleven rats at 2 wk post-MI. Next, rats were euthanized, and histological analysis for MI size was performed. Echocardiographic scans were postprocessed by a layer-specific speckle tracking program to measure the peak circumferential strain (S(C)(peak)) at the endocardium, midlayer, and epicardium as well as total wall thickness S(C)(peak). Linear regression for MI size versus S(C)(peak) showed that the slope was steeper for the endocardium compared with the other layers (P < 0.001), meaning that the endocardium was more sensitive to MI size than the other layers. Moreover, receiver operating characteristics analysis yielded better sensitivity and specificity in the detection of MI using endocardial S(C)(peak) instead of total wall thickness S(C)(peak) at 24 h post-MI (P < 0.05) but not 2 wk later. In conclusion, at acute stages of MI, before collagen deposition, scar tissue formation, and remodeling have occurred, damage may be nontransmural, and thus the use of endocardial S(C)(peak) is advantageous over total wall thickness S(C)(peak).