Left Ventricular Dyssynchrony by Three-Dimensional Echocardiography: Current Understanding and Potential Future Clinical Applications

Evaluating the predictive efficacy of real-time 3D echocardiography in cardiac resynchronization therapy

BACKGROUND

The aim of this study is to assess the predictive efficacy of real-time three-dimensional echocardiography (RT-3DE) and QRS wave duration in determining the response to cardiac resynchronization therapy (CRT) and assessing left ventricular systolic function pre- and post-CRT device implantation.

METHOD

A total of 51 patients with heart failure undergoing CRT at the Second Affiliated Hospital of Nantong University between January 1, 2013, and October 31, 2020, were enrolled in this study. Traditional two-dimensional echocardiography and RT-3DE were performed pre and post-CRT, with QRS wave width data from electrocardiograms and additional clinical information collected. Patients were categorized into CRT responder (n = 36) and CRT non-responder (n = 15) groups based on their response to CRT device implantation. Comparative analyses were conducted on the general characteristics of both groups, as well as the predictive efficacy of RT-3DE and QRS wave width for CRT responsiveness and left ventricular systolic function. Data on the standard deviation (Tmsv16-SD, Tmsv12-SD, Tmsv6-SD) and maximum difference (Tmsv16-Dif, Tmsv12-Dif, Tmsv6-Dif) of left ventricular end-systolic volume (LVESV) at segments 16, 12, and 6, as well as QRS wave width, were collected and analyzed.

RESULTS

The indicators Tmsv6-Dif, Tmsv12-Dif, Tmsv16-Dif, Tmsv6-SD, Tmsv12-SD, Tmsv16-SD, and QRS wave width exhibited significantly higher values in the CRT responder group when compared to the CRT non-responder group (P < 0.05). Among these, Tmsv16-SD demonstrated superior predictive performance for post-CRT response, with a sensitivity of 88.9%, specificity of 80.0%, and a diagnostic cut-off value of 6.19%. This predictive capability exceeded that of the conventional indicator, QRS wave width.

CONCLUSION

RT-3DE enables accurate prediction of post-CRT patient response and significantly facilitates quantitative assessment of CRT therapy efficacy.

Nkx2-5 Loss of Function in the His-Purkinje System Hampers Its Maturation and Leads to Mechanical Dysfunction

The ventricular conduction or His-Purkinje system (VCS) mediates the rapid propagation and precise delivery of electrical activity essential for the synchronization of heartbeats. Mutations in the transcription factor Nkx2-5 have been implicated in a high prevalence of developing ventricular conduction defects or arrhythmias with age. Nkx2-5 heterozygous mutant mice reproduce human phenotypes associated with a hypoplastic His-Purkinje system resulting from defective patterning of the Purkinje fiber network during development. Here, we investigated the role of Nkx2-5 in the mature VCS and the consequences of its loss on cardiac function. Neonatal deletion of Nkx2-5 in the VCS using a Cx40-CreERT2 mouse line provoked apical hypoplasia and maturation defects of the Purkinje fiber network. Genetic tracing analysis demonstrated that neonatal Cx40-positive cells fail to maintain a conductive phenotype after Nkx2-5 deletion. Moreover, we observed a progressive loss of expression of fast-conduction markers in persistent Purkinje fibers. Consequently, Nkx2-5-deleted mice developed conduction defects with progressively reduced QRS amplitude and RSR' complex associated with higher duration. Cardiac function recorded by MRI revealed a reduction in the ejection fraction in the absence of morphological changes. With age, these mice develop a ventricular diastolic dysfunction associated with dyssynchrony and wall-motion abnormalities without indication of fibrosis. These results highlight the requirement of postnatal expression of Nkx2-5 in the maturation and maintenance of a functional Purkinje fiber network to preserve contraction synchrony and cardiac function.

Coronary-specific quantification of myocardial deformation by strain echocardiography may disclose the culprit vessel in patients with non-ST-segment elevation acute coronary syndrome

Aims

To compare the diagnostic accuracy of speckle tracking echocardiography technique using territorial longitudinal strain (TLS) for the detection of culprit vessel vs. vessel-specific wall motion score index (WMSI) in non-ST-segment elevation-acute coronary syndrome (NSTE-ACS) patients scheduled for invasive coronary angiography (ICA).

Methods and results

One hundred and eighty-three patients (mean age: 66 ± 12 years, male: 71%) diagnosed with NSTE-ACS underwent echocardiography evaluation at hospital admission and ICA within 24 h. Culprit vessels were left anterior descending (LAD), left circumflex (CX), and right coronary arteries (RCAs) in 38.5%, 39.6%, and 21.4%, respectively. An increase of affected vessels [1-, 2-, and 3-vessel coronary artery disease (CAD)] was associated with increased WMSI and TLS values. There was a statistically significant difference of both WMSI-LAD, WMSI-CX, WMSI-RCA and TLS-LAD, TLS-CX, TLS-RCA of myocardial segments with underlying severe CAD compared to no CAD (P = 0.001 and P < 0.001, respectively). Moreover, a significant difference of TLS-LAD, TLS-CX, TLS-RCA, and WMSI-CX of myocardial segments with an underlying culprit vessel compared to non-culprit vessels (P < 0.001, P < 0.001, P = 0.022, and P < 0.001, respectively) was identified. WMSI-LAD and WMSI-RCA did not show statistical significant differences. A regression model revealed that the combination of WMSI + TLS was more accurate compared to WMSI alone in detecting the culprit vessel (LAD, P = 0.001; CX, P < 0.001; and RCA, P = 0.019).

Conclusion

Territorial longitudinal strain allows an accurate identification of the culprit vessel in NSTE-ACS patients. In addition to WMSI, TLS may be considered as part of routine echocardiography for better clinical assessment in this subset of patients.

Assessment of Myocardial Dysfunction by Three-Dimensional Echocardiography Combined With Myocardial Contrast Echocardiography in Type 2 Diabetes Mellitus

Background: We aimed to explore the value of combining real-time three-dimensional echocardiography (RT-3DE) and myocardial contrast echocardiography (MCE) in the left ventricle (LV) evaluating myocardial dysfunction in type 2 diabetes mellitus (T2DM) patients.

Patients and Methods: A total of 58 T2DM patients and 32 healthy individuals were selected for this study. T2DM patients were further divided into T2DM without microvascular complications (n = 29) and T2DM with microvascular complications (n = 29) subgroups. All participants underwent RT-3DE and MCE. The standard deviation (SD) and the maximum time difference (Dif) of the time to the minimum systolic volume (Tmsv) of the left ventricle were measured by RT-3DE. MCE was performed to obtain the perfusion measurement of each segment of the ventricular wall, including acoustic intensity (A), flow velocity (β), and A·β.

Results: There were significant differences in all Tmsv indices except for Tmsv6-Dif among the three groups (all P < 0.05). After heart rate correction, all Tmsv indices of the T2DM with microvascular complications group were prolonged compared with the control group (all P < 0.05). The parameters of A, β, and A·β for overall segments showed a gradually decreasing trend in three groups, while the differences between the three groups were statistically significant (all P < 0.01). For segmental evaluation of MCE, the value of A, β, and A·β in all segments showed a decreasing trend and significantly differed among the three groups (all P < 0.05).

Conclusions: The RT-3DE and MCE can detect subclinical myocardial dysfunction and impaired myocardial microvascular perfusion. Left ventricular dyssynchrony occurred in T2DM patients with or without microvascular complications and was related to left ventricular dysfunction. Myocardial perfusion was reduced in T2DM patients, presenting as diffuse damage, which was aggravated by microvascular complications in other organs.

Effects of myocardial ischemia/reperfusion injury on plasma metabolomic profile during aging

Background

Heart disease is a frequent cause of hospitalization and mortality for elderly patients. A common feature of both heart disease and aging itself is the involvement of metabolic organ alterations ultimately leading to changes in circulating metabolite levels. However, the specific contribution of aging and ischemic injury to the metabolic dysregulation occurring in older adults with ischemic heart disease is still unknown.

Aim

To evaluate the effects of aging and ischemia/reperfusion (I/R) injury on plasma metabolomic profiling in mice.

Methods

Young and aged mice were subjected to a minimally invasive model of I/R injury or sham operation. Complete evaluation of cardiac function and untargeted plasma metabolomics analysis were performed.

Results

We confirmed that aged mice from the sham group had impaired cardiac function and augmented left ventricular (LV) dimensions compared to young sham‐operated mice. Further, we found that ischemic injury did not drastically reduce LV systolic/diastolic function and dyssynchrony in aged compared to young mice. Using an untargeted metabolomics approach focused on aqueous metabolites, we found that ischemic injury does not affect the plasma metabolomic profile either in young or old mice. Our data also demonstrate that age significantly affects circulating metabolite levels (predominantly amino acids, phospholipids and organic acids) and perturbs several pathways involved in amino acid, glucid and nucleic acid metabolism as well as pyridoxal‐5′‐phosphate salvage pathway in both sham and ischemic mice.

Conclusions

Our approach increases our understanding of age‐associated plasma metabolomic signatures in mice with and without heart disease excluding confounding factors related to metabolic comorbidities.

Deep learning in spatiotemporal cardiac imaging: A review of methodologies and clinical usability

The use of different cardiac imaging modalities such as MRI, CT or ultrasound enables the visualization and interpretation of altered morphological structures and function of the heart. In recent years, there has been an increasing interest in AI and deep learning that take into account spatial and temporal information in medical image analysis. In particular, deep learning tools using temporal information in image processing have not yet found their way into daily clinical practice, despite its presumed high diagnostic and prognostic value. This review aims to synthesize the most relevant deep learning methods and discuss their clinical usability in dynamic cardiac imaging using for example the complete spatiotemporal image information of the heart cycle. Selected articles were categorized according to the following indicators: clinical applications, quality of datasets, preprocessing and annotation, learning methods and training strategy, and test performance. Clinical usability was evaluated based on these criteria by classifying the selected papers into (i) clinical level, (ii) robust candidate and (iii) proof of concept applications. Interestingly, not a single one of the reviewed papers was classified as a "clinical level" study. Almost 39% of the articles achieved a "robust candidate" and as many as 61% a "proof of concept" status. In summary, deep learning in spatiotemporal cardiac imaging is still strongly research-oriented and its implementation in clinical application still requires considerable efforts. Challenges that need to be addressed are the quality of datasets together with clinical verification and validation of the performance achieved by the used method.

Three-dimensional echocardiography to assess left ventricular geometry and function

Introduction: Quantification of left ventricular (LV) size and function represents the most frequent indication for an echocardiographic study. New echocardiographic techniques have been developed over the last decades in an attempt to provide a more comprehensive, accurate, and reproducible assessment of LV function.Areas covered: Although two-dimensional echocardiography (2DE) is the recommended imaging modality to evaluate the LV, three-dimensional echocardiography (3DE) has proven to be more accurate, by avoiding geometric assumptions about LV geometry, and to have incremental value for outcome prediction in comparison to conventional 2DE. LV shape (sphericity) and mass are actually measured with 3DE. Myocardial deformation analysis using 3DE can early detect subclinical LV dysfunction, before any detectable change in LV ejection fraction.Expert opinion: 3DE eliminates the errors associated with foreshortening and geometric assumptions inherent to 2DE and 3DE measurements approach very closely those obtained by CMR (the current reference modality), while maintaining the unique clinical advantage of a safe, highly cost/effective, portable imaging technique, available to the cardiologist at bedside to translate immediately the echocardiography findings into the clinical decision-making process.

Echocardiographic Strain Analysis for the Early Detection of Left Ventricular Systolic/Diastolic Dysfunction and Dyssynchrony in a Mouse Model of Physiological Aging

Heart disease is the leading cause of hospitalization and death worldwide, severely affecting health care costs. Aging is a significant risk factor for heart disease, and the senescent heart is characterized by structural and functional changes including diastolic and systolic dysfunction as well as left ventricular (LV) dyssynchrony. Speckle tracking-based strain echocardiography (STE) has been shown as a noninvasive, reproducible, and highly sensitive methodology to evaluate LV function in both animal models and humans. Herein, we describe the efficiency of this technique as a comprehensive and sensitive method for the detection of age-related cardiac dysfunction in mice. Compared with conventional echocardiographic measurements, radial and longitudinal strain, and reverse longitudinal strain were able to detect subtle changes in systolic and diastolic cardiac function in mice at an earlier time point during aging. Additionally, the data show a gradual and consistent decrease with age in regional contractility throughout the entire LV, in both radial and longitudinal axes. Furthermore, we observed that LV segmental dyssynchrony in longitudinal axis reliably differentiated between aged and young mice. Therefore, we propose the use of echocardiographic strain as a highly sensitive and accurate technology enabling and evaluating the effect of new treatments to fight age-induced cardiac disease.

Reproducibility of Left Ventricular Dyssynchrony Indices by Three-Dimensional Speckle-Tracking Echocardiography: The Impact of Sub-optimal Image Quality

Background: 3D speckle-tracking echocardiography (3D-STE) is a novel method to quantify left ventricular (LV) mechanical dyssynchrony. 3D-STE is influenced by image quality, but studies on the magnitude of its effect on 3D-STE derived LV systolic dyssynchrony indices (SDIs) and their test-retest reproducibility are limited. Methods: 3D-STE was performed in two groups, each comprising 18 healthy volunteers with good echocardiographic windows. In study 1, optimal and inferior-quality images, by intentionally poor echocardiographic technique, were acquired. In study 2, sub-optimal quality images were acquired by impairing ultrasound propagation using neoprene rubber sheets (thickness 2, 3, and 4 mm) mimicking mildly, moderately, and severely impaired images, respectively. Measures (normalized to cardiac cycle duration) were volume- and strain-based SDIs defined as the standard deviation of time to minimum segmental values, and volume- and strain-derived dispersion indices. For both studies test-retest reproducibility was assessed. Results: Test-retest reproducibility was better for most indices when restricting the analysis to good quality images; nevertheless, only volume-, circumferential strain-, and principal tangential strain-derived LV dyssynchrony indices achieved fair to good reliability. There was no evidence of systematic bias due to sub-optimal quality image. Volume-, circumferential strain-, and principal tangential strain-derived SDIs correlated closely. Radial strain- and longitudinal strain-SDI correlated moderately or weakly with volume-SDI, respectively. Conclusions: Sub-optimal image quality compromised the reliability of 3D-STE derived dyssynchrony indices but did not introduce systematic bias in healthy individuals. Even with optimal quality images, only 3D-STE indices based on volume, circumferential strain and principal tangential strain showed acceptable test-retest reliability.

Left ventricular dyssynchrony in coronary artery disease patients without regional wall-motion abnormality: Correlation with Gensini score

OBJECTIVES

Our study investigated left ventricular dyssynchrony (LVD) in coronary artery disease (CAD) patients without regional wall-motion abnormality (RWMA) by three-dimensional echocardiography (3-DE) and explored the relationship between LVD and severity of CAD as assessed by the Gensini score (GS).

METHODS

Sixty-one patients with a confirmed diagnosis of CAD by coronary angiography (CAG) were enrolled. We quantified LVD parameters, including the left ventricular segments (16, 12, and 6) standard deviation of the time to minimum systolic volume (TmsvSD-16, TmsvSD-12, and TmsvSD-6) and the systolic dyssynchrony index in regions 16, 12, and 6 (16R-SDI, 12R-SDI, 6R-SDI) using 3-DE. The severity of coronary atherosclerotic lesions was evaluated by the GS system on the basis of CAG findings. We further divided all patients into three groups according to the tertiles of GS: low-GS ≤20, mid-GS >20 and ≤48, and high-GS >48. The differences of LVD values among the three groups were compared, and the associations between LVD parameters and GS were analyzed.

RESULTS

Coronary artery disease patients demonstrated increased LVD parameters compared with healthy controls. TmsvSD12, 16R-SDI, and 6R-SDI were prolonged in the high-GS group compared with the low- and mid-GS groups. 16R-SDI was positively correlated with the GS, and multivariate regression analysis showed that 16R-SDI was an independent predictor of the GS. 16R-SDI above 10.7% had a sensitivity of 84.21% and a specificity of 92.86% for identifying high-GS.

CONCLUSION

Three-dimensional echocardiography is a noninvasive technique to detect LVD in non-RWMA CAD patients, and the parameter 16R-SDI was significantly correlated with CAD severity.

Predictive value of global and territorial longitudinal strain imaging in detecting significant coronary artery disease in patients with myocardial infarction without persistent ST-segment elevation

INTRODUCTION

Two-dimensional (2D) speckle-tracking echocardiographic (STE) imaging is frequently performed in the assessment of cardiovascular diseases. We aim to investigate the role of the global and territorial longitudinal strain (GLS and TLS) values assessed via 2D STE imaging to detect significant coronary artery disease (CAD) in non-ST-segment elevation myocardial infarction (NSTEMI) patients without wall-motion abnormalities.

METHODS

This study enrolled 150 patients with the diagnosis of NSTEMI. Patients who had typical chest pain with unstable angina characteristics within the last 24 hours were 18-80 years of age and had a typical rise and/or fall of cardiac biomarkers were included. Myocardial functions were assessed via myocardial deformation analyses of 2D STE images.

RESULTS

The mean age of the CAD group was 52.91 ± 9.11, vs 50.31 ± 8.32 in the control group. In the CAD group, 56 patients were male (65%), whereas 21 were male (60%) in control group. GLS and TLS assessments demonstrated a statistically significant difference between CAD and control groups, with GLS values of -16.27 ± 1.91 and -18.74 ± 1.93 (P < 0.001), TLS-LAD values of -15.67 ± 1.83 and -18.54 ± 1.97 (P < 0.001), TLS-RCA values of -17.04 ± 1.81 and -19.20 ± 1.86 (P < 0.001), and TLS-Cx values of -17.40 ± 2.08 and -18.34 ± 2.18 (P = 0.028), respectively. Correlation analyses revealed that as high-sensitivity troponin (hsTnT) values increased, GLS decreased significantly, and further, an increase in severity of CAD resulted in decreased TLS-LAD, -CX and -RCA (TLS-LAD: P < 0.001, r = -0.743; TLS-CX: P < 0.001, r = -0.449; TLS-RCA: P < 0.001, r = -0.737). Multivariate analyses indicated that GLS and GRACE ACS risk scores are independent predictors of CAD in patients with NSTEMI (GLS: OR = 0.514, P < 0.001; GRACE score: OR = 0.938, P = 0.007).

CONCLUSIONS

Global longitudinal strain (GLS) assessed with 2D STE is a promising, easy to perform and quick imaging method to predict CAD in patients with NSTEMI.

Relationship between left ventricular diastolic dyssynchrony and systolic dyssynchrony in hypertrophic cardiomyopathy by single-cardiac real-time three-dimensional ultrasonography

The relationship between left ventricular diastolic and systolic dyssynchrony in hypertrophic cardiomyopathy (HCM) was investigated by single-cardiac real-time three-dimensional ultrasonography. A total of 52 patients with HCM were selected in Jining No. 1 People's Hospital from July 2016 to June 2017. Additionally, a total of 52 healthy people were selected to serve as the control group. All participants received real-time two- and three-dimensional ultrasonography to evaluate left ventricular morphology, function and systolic and diastolic function. The relevant parameters included left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), end-systolic/diastolic sphericity index (ESSI/EDSI), systolic dyssynchrony index (SDI), diastolic dyssynchrony index (DDI), dispersion end systole (DISPES), diastolic dyssynchrony index-late (DDI-late) and dispersion end diastole (DISPED-late). The LVEF of observation group was significantly lower than that of the control group, while LVEDV, LVESV, E/A and E/Ea were significantly higher than those in control group (P<0.05); EDSI, DDI-late and DISPED-late were significantly higher in observation than in control group (P<0.05); ESSI, SDI and DISPES in observation were significantly higher than those in control group (P<0.05); The 16-segment time-volume curve of observation group was disordered without synchronization, while the curve of control group was regular and smooth with synchronization; Pearson's correlation analysis showed that SDI and DDI were positively correlated (P<0.05). In conclusion, three-dimensional ultrasonography can be used to effectively evaluate left ventricular diastolic and systolic dyssynchrony in HCM. The severity of diastolic is positively correlated with systolic dyssynchrony.

2-Dimensional Speckle Tracking Echocardiography predicts severe coronary artery disease in women with normal left ventricular function: a case-control study

Background

Women who have coronary artery disease (CAD) often present with atypical symptoms that may lead to misdiagnosis. We assessed strain, systolic strain rate and left ventricular dyssynchrony with 2- dimensional- speckle tracking echocardiography to evaluate its use as a non-invasive method for detecting CAD in women with normal ejection fraction compared with healthy women controls with a normal angiogram.

Methods

We included 35 women with CAD confirmed by coronary angiography and a positive exercise stress echocardiography and 35 women in a control group with a low pretest probability of CAD, normal angiogram and a normal stress echocardiography with normal EF.

Results

Statistically significant 2D-STE findings for the CAD vs control groups were as follows for the mean of: global circumferential strain (CS) (−19.4% vs −22.4%, P = .02); global radial S (49% vs 34%, P = .03); global radial SR (2.4 s⁻¹ vs 1.9 s⁻¹, P = .05); global longitudinal LV S (GLS) (−14.3% vs −17.2%, P < .001). For mechanical dyssynchrony, SD of the GLS time-to-peak (TTP) was computed (99 vs 33 ms, P < .001). The receiver operating characteristic and area under the curve (AUC) were calculated. A cutoff value of 45 ms for 1 SD of the longitudinal S TTP had 97% sensitivity and 89% specificity (AUC, 0.96). GLS cutoff value of −15.87% had 71% sensitivity and 74% specificity; AUC, 0.74 in differentiating CAD and control groups. The combined GLS, CS, and SD of the longitudinal S TTP had an AUC of 0.96 (sensitivity 97%, specificity 86%). Interclass correlations of the GLS segment and GLS TTP measurements were 0.49 (95% CI, 0.227-0.868) and 0.74 (95% CI, 0.277-0.926), respectively.

Conclusion

In women with a normal echocardiogram and LVEF, CAD can be identified by dyssynchrony and abnormal strain values, as evidenced by 2D-STE.

Strain Imaging Echocardiography: What Imaging Cardiologists Should Know

Despite recent advances in clinical imaging, echocardiography remains as the most accessi-ble and reliable noninvasive. Since knowledge of left ventricular systolic function remains so critically important in determining prognosis; every effort should be made to prevent subjective estimations. The advent of strain imaging echocardiography now offers a readily available and portable imaging tool that not only offers an objective characterization of myocardial dynamics; but also allows for early detection of subclinical left ventricular dysfunction. This review outlines the basic concepts of strain imaging to better understand the mechanism of myocardial function as well their applicability in the least common cardiac diagnosis among current clinical practice.