Prediction of prognosis in patients with left ventricular dysfunction using three-dimensional strain echocardiography and cardiac magnetic resonance imaging

BACKGROUND

We evaluated three-dimensional speckle tracking echocardiography (3DSTE) strain and cardiac magnetic resonance (CMR) with delayed contrast enhancement (DCE) for the prediction of cardiac events in left ventricular (LV) dysfunction.

METHODS

CMR and 3DSTE in 75 patients with ischaemic and 38 with non-ischaemic LV dysfunction were analysed and temporally correlated to cardiac events during 41 ± 9 months of follow-up.

RESULTS

Cardiac events occurred in 44 patients, more in patients with ischaemic LV dysfunction. LV ejection fraction (LVEF), global circumferential and global area strain were reduced more in patients with more cardiac events, whereas 3DSTE LV end-systolic volumes and 3DSTE LV masses were larger. However, the area under the curve using receiver-operating characteristic analysis showed modest sensitivity and specificity for all evaluated parameters. Additionally, DCE did not differ significantly between the two groups. Univariate analysis showed ischaemic aetiology of LV dysfunction, LVEF and LV mass by CMR to be predictors of cardiac events with an increased relative risk of 2.4, 1.6 and 1.5, respectively. By multivariate analysis, only myocardial ischaemia and LVEF ≤ 39% were independent predictors of events (p = 0.004 and 0.005, respectively). Subgroup analysis in ischaemic and non-ischaemic patients showed only 3DSTE LV mass in ischaemic patients to have a significant association (p = 0.033) but without an increased relative risk.

CONCLUSION

LVEF calculated by 3DSTE or CMR were both good predictors of cardiac events in patients with LV dysfunction. A reduced LVEF ≤ 39% was associated with a 1.6-fold higher probability of a cardiac event. 3DSTE strain measurements and DCE-CMR did not add to the prognostic value of LVEF.

Systematic Comparison of Left Ventricular Geometry Between 3D-Echocardiography and Cardiac Magnetic Resonance Imaging

Aims: Left ventricular (LV) volumes estimated using three-dimensional echocardiography (3D-echo) have been reported to be smaller than those measured using cardiac magnetic resonance (CMR) imaging, but the underlying causes are not well-understood. We investigated differences in regional LV anatomy derived from these modalities and related subsequent findings to image characteristics. Methods and Results: Seventy participants (18 patients and 52 healthy participants) were imaged with 3D-echo and CMR (<1 h apart). Three-dimensional left ventricular models were constructed at end-diastole (ED) and end-systole (ES) from both modalities using previously validated software, enabling the fusion of CMR with 3D-echo by rigid registration. Regional differences were evaluated as mean surface distances for each of the 17 American Heart Association segments, and by comparing contours superimposed on images from each modality. In comparison to CMR-derived models, 3D-echo models underestimated LV end-diastolic volume (EDV) by -16 ± 22, -1 ± 25, and -18 ± 24 ml across three independent analysis methods. Average surface distance errors were largest in the basal-anterolateral segment (11-15 mm) and smallest in the mid-inferoseptal segment (6 mm). Larger errors were associated with signal dropout in anterior regions and the appearance of trabeculae at the lateral wall. Conclusions: Fusion of CMR and 3D-echo provides insight into the causes of volume underestimation by 3D-echo. Systematic signal dropout and differences in appearances of trabeculae lead to discrepancies in the delineation of LV geometry at anterior and lateral regions. A better understanding of error sources across modalities may improve correlation of clinical indices between 3D-echo and CMR.

Spatio-Temporal Segmentation in 3-D Echocardiographic Sequences Using Fractional Brownian Motion

An important aspect for an improved cardiac functional analysis is the accurate segmentation of the left ventricle (LV). A novel approach for fully-automated segmentation of the LV endocardium and epicardium contours is presented. This is mainly based on the natural physical characteristics of the LV shape structure. Both sides of the LV boundaries exhibit natural elliptical curvatures by having details on various scales, i.e. exhibiting fractal-like characteristics. The fractional Brownian motion (fBm), which is a non-stationary stochastic process, integrates well with the stochastic nature of ultrasound echoes. It has the advantage of representing a wide range of non-stationary signals and can quantify statistical local self-similarity throughout the time-sequence ultrasound images. The locally characterized boundaries of the fBm segmented LV were further iteratively refined using global information by means of second-order moments. The method is benchmarked using synthetic 3D+time echocardiographic sequences for normal and different ischemic cardiomyopathy, and results compared with state-of-the-art LV segmentation. Furthermore, the framework was validated against real data from canine cases with expert-defined segmentations and demonstrated improved accuracy. The fBm-based segmentation algorithm is fully automatic and has the potential to be used clinically together with 3D echocardiography for improved cardiovascular disease diagnosis.

An image fusion tool for echo-guided left ventricular lead placement in cardiac resynchronization therapy: Performance and workflow integration analysis

BACKGROUND

The response rate to cardiac resynchronization therapy (CRT) may be improved if echocardiographic-derived parameters are used to guide the left ventricular (LV) lead deployment. Tools to visually integrate deformation imaging and fluoroscopy to take advantage of the combined information are lacking.

METHODS

An image fusion tool for echo-guided LV lead placement in CRT was developed. A personalized average 3D cardiac model aided visualization of patient-specific LV function in fluoroscopy. A set of coronary venography-derived landmarks facilitated registration of the 3D model with fluoroscopy into a single multimodality image. The fusion was both performed and analyzed retrospectively in 30 cases. Baseline time-to-peak values from echocardiography speckle-tracking radial strain traces were color-coded onto the fused LV. LV segments with suspected scar tissue were excluded by cardiac magnetic resonance imaging. The postoperative augmented image was used to investigate: (a) registration accuracy and (b) agreement between LV pacing lead location, echo-defined target segments, and CRT response.

RESULTS

Registration time (264 ± 25 seconds) and accuracy (4.3 ± 2.3 mm) were found clinically acceptable. A good agreement between pacing location and echo-suggested segments was found in 20 (out of 21) CRT responders. Perioperative integration of the proposed workflow was successfully tested in 2 patients. No additional radiation, compared with the existing workflow, was required.

CONCLUSIONS

The fusion tool facilitates understanding of the spatial relationship between the coronary veins and the LV function and may help targeted LV lead delivery.

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.

Changes in speckle-tracking-derived mechanical dispersion index are associated with 30-day readmissions in acute heart failure

Background

The objective of the present study was to evaluate the relationship between speckle-tracking-derived parameters left ventricular (LV) mechanical dispersion index (MDI), defined as the standard deviation of the time-to-peak longitudinal strain of all segments analyzed of the LV, and global longitudinal strain (GLS) and 30-day post-discharge outcomes (death and readmission to the hospital) in patients with acute heart failure (AHF).

Methods

We performed a prospective observational study of selected emergency department patients with a primary diagnosis of AHF. Point-of-care echocardiograms were performed at baseline (prior to, or concurrent with the initiation of treatment) and 23 h post-enrollment. Offline speckle-tracking analysis was utilized to calculate GLS and MDI. The primary outcome was 30-day readmissions.

Results

A total of 31 patients were included, 13 of whom were readmitted within 30 days. Patients who were not readmitted to the hospital experienced an average relative improvement in MDI of 24% from baseline to 23 h (84 ms to 64 ms), while patients who were readmitted experienced an average relative worsening in MDI of 6% (66 ms to 70 ms) from baseline to 23 h.

Conclusions

MDI has promise as a treatment response variable in admitted patients with AHF; however, further study is needed.

The impact of multipole pacing on left ventricular function in patients with cardiac resynchronization therapy - A real-time three-dimensional echocardiography approach

BACKGROUND

Cardiac resynchronization therapy (CRT) is standard of care in heart failure (HF), however this technique is associated with a non-responder rate of 30%. Multipole pacing (MPP) with a quadripolar lead may optimize CRT and responder rate by creating two electrical wave fronts in the left ventricular (LV) myocardium simultaneously in order to reduce mechanical dyssynchrony. The objective of this study was to investigate the acute impact of MPP on LV function by assessing systolic dyssynchrony index (SDI) and left ventricular ejection fraction (LVEF) via real-time three-dimensional echocardiography (RT3DE).

METHODS

In 41 consecutive patients (87.8% male; mean age 66.0 ± 12.7 years) who received CRT defibrillators with a quadripolar LV lead, RT3DE datasets were acquired the day after implantation under the following pacing configurations: Baseline AAI, conventional biventricular pacing using distal or proximal LV poles and MPP. Datasets were analyzed in paired samples evaluating SDI and LVEF depending on programmed pacing modality.

RESULTS

MPP resulted in statistically significant reduction of SDI compared to baseline (6.3%; IQR 4.4-7.8 and 9.9%; IQR 8.0-12.7; p < 0.001) and to conventional biventricular pacing using distal (7.6%; IQR 6.5-9.1; p < 0.001) or proximal (7.4%; IQR 6.2-8.8; p < 0.001) LV poles respectively. MPP yielded significant increase in LVEF compared to baseline (30.6%; IQR 25.8-37.5 and 27.2%; IQR 21.1-33.6; p < 0.001) and to conventional biventricular pacing configuration with distal (28.1%; IQR 22.1-34.5; p < 0.001) or proximal (28.6%; IQR 23.2-34.9; p < 0.001) LV poles respectively.

CONCLUSIONS

Multipole pacing improves mechanical dyssynchrony of the left ventricular myocardium as assessed by SDI and LVEF.

The Role of Echocardiography in the Optimization of Cardiac Resynchronization Therapy: Current Evidence and Future Perspectives

Background:

Cardiac resynchronization therapy (CRT) has become a mainstay in the management of heart failure. Up to one-third of patients who received resynchronization devices do not experience the full benefits of CRT. The clinical factors influencing the likelihood to respond to the therapy are wide QRS complex, left bundle branch block, female gender, non-ischaemic cardiomyopathy (highest responders), male gender, ischaemic cardiomyopathy (moderate responders) and narrow QRS complex, non-left bundle branch block (lowest, non-responders).

Objective:

This review provides a conceptual description of the role of echocardiography in the optimization of CRT.

Method:

A literature survey was performed using PubMed database search to gather information regarding CRT and echocardiography.

Results:

A total of 70 studies met selection criteria for inclusion in the review. Echocardiography helps in the initial selection of the patients with dyssynchrony, which will benefit the most from optimal biventricular pacing and provides a guide to left ventricular (LV) lead placement during implantation. Different echocardiographic parameters have shown promise and can offer the possibility of patient selection, response prediction, lead placement optimization strategies and optimization of device configurations.

Conclusion:

LV ejection fraction along with specific electrocardiographic criteria remains the cornerstone of CRT patient selection. Echocardiography is a non-invasive, cost-effective, highly reproducible method with certain limitations and accuracy that is affected by measurement errors. Echocardiography can assist with the identification of the appropriate electromechanical substrate of CRT response and LV lead placement. The targeted approach can improve the haemodynamic response, as also the patient-specific parameters estimation.

Reliability of Left Ventricular Ejection Fraction from Three-Dimensional Echocardiography for Cardiotoxicity Onset Detection in Patients with Breast Cancer

BACKGROUND

Cardiotoxicity is a well-known adverse effect of various chemotherapeutic agents that can be monitored by echocardiography. A decrease in left ventricular ejection fraction (LVEF) triggers consideration for therapy modification or interruption. The aim of this study was to evaluate how variability in LVEF estimates computed using three-dimensional echocardiography could influence cardiotoxicity onset detection.

METHODS

One hundred eighty one patients with breast cancer treated with anthracycline and trastuzumab were analyzed. LVEF was computed using two commercial software packages. In a subgroup of 40 patients, three-dimensional echocardiographic data were reanalyzed to assess intra- and interobserver variability by two expert investigators using both packages. Global longitudinal strain (GLS) imaging was evaluated in 64 patients.

RESULTS

End-diastolic volume, end-systolic volume, and LVEF measurements obtained applying the two software packages were in good agreement, with small bias and acceptable limits of agreement. Intra- and interobserver variability was smaller using one of the two software packages. However, for both packages, variability indexes were in the range of affecting LVEF estimates at a level that could lead to an inaccurate assessment of cardiac adverse effects of cancer therapeutic drugs. On the basis of LVEF, 11 of 181 patients (6.1%) had cardiotoxicity at 3-month follow-up. The absolute value of GLS was smaller in 16 of 64 patients (25%) thought to have cardiotoxicity on the basis of GLS results, including six of seven patients who had cardiotoxicity considering LVEF in this subgroup.

CONCLUSIONS

Following clinical definition of cardiotoxicity onset, variability in LVEF computation by three-dimensional echocardiography could be a confounding factor for cardiotoxicity diagnosis, and different software packages should not be used interchangeably for LVEF monitoring. GLS confirms its predictive value for subsequent cardiotoxicity.

Newer Echocardiographic Techniques in Cardiac Resynchronization Therapy

Echocardiographic imaging plays a major role in patient selection for cardiac resynchronization therapy (CRT). One-third of patients do not respond; there is interest in advanced echocardiographic imaging to improve response. Current guidelines favor CRT for patients with electrocardiographic (ECG) QRS width of 150 milliseconds or greater and left bundle branch block. ECG criteria are imperfect; there is interest in advanced echocardiographic imaging to improve patient selection. This discussion focuses on newer echocardiographic methods to improve patient selection, improve delivery, and identify patients at risk for poor outcomes and serious ventricular arrhythmias.

Echocardiography and cardiac resynchronisation therapy, friends or foes?

Echocardiography is used in cardiac resynchronisation therapy (CRT) to assess cardiac function, and in particular left ventricular (LV) volumetric status, and prediction of response. Despite its widespread applicability, LV volumes determined by echocardiography have inherent measurement errors, interobserver and intraobserver variability, and discrepancies with the gold standard magnetic resonance imaging. Echocardiographic predictors of CRT response are based on mechanical dyssynchrony. However, parameters are mainly tested in single-centre studies or lack feasibility. Speckle tracking echocardiography can guide LV lead placement, improving volumetric response and clinical outcome by guiding lead positioning towards the latest contracting segment. Results on optimisation of CRT device settings using echocardiographic indices have so far been rather disappointing, as results suffer from noise. Defining response by echocardiography seems valid, although re-assessment after 6 months is advisable, as patients can show both continuous improvement as well as deterioration after the initial response. Three-dimensional echocardiography is interesting for future implications, as it can determine volume, dyssynchrony and viability in a single recording, although image quality needs to be adequate. Deformation patterns from the septum and the derived parameters are promising, although validation in a multicentre trial is required. We conclude that echocardiography has a pivotal role in CRT, although clinicians should know its shortcomings.

Newer Echocardiographic Techniques in Cardiac Resynchronization Therapy

Echocardiographic imaging plays a major role in patient selection for cardiac resynchronization therapy (CRT). One-third of patients do not respond; there is interest in advanced echocardiographic imaging to improve response. Current guidelines favor CRT for patients with electrocardiographic (ECG) QRS width of 150 milliseconds or greater and left bundle branch block. ECG criteria are imperfect; there is interest in advanced echocardiographic imaging to improve patient selection. This discussion focuses on newer echocardiographic methods to improve patient selection, improve delivery, and identify patients at risk for poor outcomes and serious ventricular arrhythmias.

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

Left ventricular mechanical dyssynchrony is an important prognostic factor for patients with symptomatic systolic heart failure and has emerged as a therapeutic target for cardiac resynchronization therapy (CRT). However, approximately one-third of patients fail to improve after CRT based on current guideline recommendations and electrocardiographic criteria. Two-dimensional echocardiography and tissue Doppler-based techniques have shown variable results in assessment of left ventricular (LV) dyssynchrony and have limited value in clinical practice. Three-dimensional echocardiography (3DE) is an appealing novel imaging modality that has been recently used in quantitative evaluation of global and regional LV function. There is accumulating evidence that 3DE measurement of LV systolic dyssynchrony index may potentially play a role in predicting the short- and long-term response to CRT and further improve patient selection for CRT. New developments in 3DE speckle tracking technique and strain analysis may further improve the accuracy of LV mechanical dyssynchrony assessment in this population. In addition, recent studies suggest that mechanical dyssynchrony is present in patients with LV hypertrophy and diastolic heart failure. Three-dimensional echocardiographic assessment of dyssynchrony may aid in diagnosis and in predicting long-term outcome in these patients. We will summarize current understanding of 3DE techniques and parameters in assessment of LV mechanical dyssynchrony in the population of patients with systolic heart failure, LV hypertrophy, and diastolic heart failure. A number of the novel 3DE techniques described in this review are early in their stage of development, and they will continue to evolve and need further testing in large multicenter studies.

Comparison of septal strain patterns in dyssynchronous heart failure between speckle tracking echocardiography vendor systems

AIM

To analyze inter-vendor differences of speckle tracking echocardiography (STE) in imaging cardiac deformation in patients with dyssynchronous heart failure.

METHODS AND RESULTS

Eleven patients (all with LBBB, median age 60.7 years, 9 males) with implanted cardiac resynchronization therapy devices were prospectively included. Ultrasound systems of two vendors (i.e. General Electric and Philips) were used to record images in the apical four chamber view. Regional longitudinal strain patterns were analyzed with vendor specific software in the basal, mid and apical septal segments. Systolic strain (SS), time to peak strain (TTP) and septal rebound stretch (SRS) were determined during four pacing settings, resulting in 44 unique strain patterns per segment (total 132 patterns). Cross correlation was used to analyze the comparability of the shape of 132 normalized strain patterns. Correlation of strain patterns of the two systems was high (R(2) median: 0.68, interquartile range: 0.53-0.82). Accordingly, strain patterns of intrinsic rhythm were recognized equally using both systems, when divided into three types. GE based SS (18.9 ± 4.7%) was significantly higher than SS determined by the Philips system (13.4 ± 4.3%). TTP was slightly but non-significantly lower in GE (384 ± 77 ms) compared to Philips (404 ± 83 ms) derived strain signals. Correlation of SRS between the systems was poor, due to minor differences in the strain signal and timing of aortic valve closure.

CONCLUSIONS

The two systems provide similar shape of strain patterns. However, important differences are found in the amplitude, timing of systole and SRS. Until STE is standardized, clinical decision making should be restricted to pattern analysis.