Predictive value of left ventricular dyssynchrony for short-term outcomes in three-vessel disease patients undergoing coronary artery bypass grafting with preserved or mildly reduced left ventricular ejection fraction

Background and objective

Coronary artery bypass grafting (CABG) is the reference standard intervention in coronary artery disease (CAD) patients with three-vessel disease (3VD). We aimed to evaluate the predictive value of left ventricular (LV) dyssynchrony for short-term adverse outcomes in patients with 3VD undergoing CABG with preserved or mildly reduced LV ejection fraction (LVEF).

Materials and methods

This study involved ninety-five 3VD patients with preserved or mildly reduced LVEF undergoing scheduled on-pump CABG. The pre-operative diameters and volumes of LV and LVEF were obtained by two-dimensional echocardiography. LV dyssynchrony parameters were acquired by real-time three-dimensional echocardiography (RT-3DE) and analyzed by HeartModel quantification software. And the perfusion index of LV was obtained by contrast echocardiography. The clinical endpoints of short-term adverse outcomes comprised 30-day mortality and/or composite outcomes of postoperative complications. Univariate and multivariate logistic regression analyses were used to identify risk factors for the occurrence of post-CABG short-term adverse outcomes.

Results

Short-term adverse outcomes occurred in 12 (12.6%) patients. These patients had higher LV dyssynchrony parameters obtained through RT-3DE. The standard deviation (SD) of the time to minimum systolic volume (Tmsv) corrected by heart rate over 16 segments (Tmsv16-SD%) [odds ratio (OR), 1.362; 95% confidence interval (CI) (1.090–1.702); P = 0.006], one of the LV dyssynchrony parameters, was independently associated with short-term adverse outcomes. Patients with poor synchronization tended to spend more time in the intensive care unit (ICU) and hospital after surgery.

Conclusion

Pre-operative LV dyssynchrony parameter Tmsv16-SD% obtained through RT-3DE could be a useful additional predictor of postoperative short-term adverse outcomes in 3VD patients with preserved or mildly reduced LVEF undergoing CABG.

Real-time three-dimensional echocardiography for detection of cardiac sarcoidosis in the early stage: a cross-sectional single-centre study

BACKGROUND

Sarcoidosis with cardiac involvement has a relatively high morbidity and mortality, and early diagnose of cardiac sarcoidosis is a critical issue. Systolic dyssynchrony index (SDI) measured by three-dimensional echocardiography was used in our study for detection of subclinical left ventricular (LV) systolic dysfunction in patients with sarcoidosis and normal LV function on two-dimensional echocardiography.

METHODS

Forty-four patients diagnosed with sarcoidosis (without clinically apparent cardiac involvement) and 44 healthy control subjects were included in this study. Two-dimensional echocardiographic parameters, also LV volumes and SDI measured by 3D echocardiography were analyzed in all participants.

RESULTS

While two-dimensional echocardiographic results of both study groups were similar; SDI_16 (SDI for 16 segments of LV) results were significantly higher in sarcoidosis group compared to healthy controls (6.99 ±5.02 vs 2.89 ± 1.32, p < 0.0001).

CONCLUSION

SDI_16 was higher in patients with sarcoidosis compared to healthy controls probably due to patchy infiltration characteristic of the disease. This parameter could be used as a marker to identify patients with cardiac involvement of sarcoidosis in the early phase.

Imaging Protocol, Feasibility, and Reproducibility of Cardiovascular Phenotyping in a Large Tri-Ethnic Population-Based Study of Older People: The Southall and Brent Revisited (SABRE) Study

Background: People of South Asian and African Caribbean ethnicities living in UK have a high risk of cardiometabolic disease. Limited data exist regarding detailed cardiometabolic phenotyping in this population. Methods enabling this are widely available, but the practical aspects of undertaking such studies in large and diverse samples are seldom reported. Methods: The Southall and Brent Revisited (SABRE) study is the UK's largest tri-ethnic longitudinal cohort. Over 1,400 surviving participants (58-85 years) attended the 2nd study visit (2008-2011); during which, comprehensive cardiovascular phenotyping, including 3D-echocardiography [3D-speckle-tracking (3D-STE)], computed tomography, coronary artery calcium scoring, pulse wave velocity, central blood pressure, carotid artery ultrasound, and retinal imaging, were performed. We describe the methods used with the aim of providing a guide to their feasibility and reproducibility in a large tri-ethnic population-based study of older people. Results: Conventional echocardiography and all vascular measurements showed high feasibility (>90% analyzable of clinic attendees), but 3D-echocardiography (3DE) and 3D-STE were less feasible (76% 3DE acquisition feasibility and 38% 3D-STE feasibility of clinic attendees). 3D-STE feasibility differed by ethnicity, being lowest in South Asian participants and highest in African Caribbean participants (p < 0.0001). Similar trends were observed in men (P < 0.0001) and women (P = 0.005); however, in South Asians, there were more women with unreadable 3D-images compared to men (67 vs. 58%). Intra- and inter-observer variabilities were excellent for most of conventional and advanced echocardiographic measures. The test-retest reproducibility was good-excellent and fair-good for conventional and advanced echocardiographic measures, respectively, but lower than when re-reading the same images. All vascular measures demonstrated excellent or fair-good reproducibility. Conclusions: We describe the feasibility and reproducibility of detailed cardiovascular phenotyping in an ethnically diverse population. The data collected will lead to a better understanding of why people of South Asian and African Caribbean ancestry are at elevated risk of cardiometabolic diseases.

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.

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.

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.

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.

The clinical dilemma of quantifying mechanical left ventricular dyssynchrony for cardiac resynchronization therapy: segmental or global?

Heart failure (HF) represents a serious clinical and public cause of mortality, morbidity, as well as healthcare expenditures. Guidelines for treatment of HF join in recommending multimedical regimen at targeted doses as the best medical strategy, despite that a significant percentage of patients remain symptomatic. Studies have shown that these patients might benefit from cardiac resynchronization therapy (CRT), particularly those presenting with broad QRS duration, >135 msec. Trials have already shown that CRT results in improved morbidity and survival of these patients particularly those in New York Heart Association class III-IV HF, but almost 30% do not show any symptomatic or survival benefit, hence are classified as nonresponders. Exhaustive efforts have been made in using noninvasive methods of assessing left ventricle (LV) dyssynchrony in predicting nonresponders to CRT, including Doppler echocardiography, magnetic resonance imaging, and even single photon emission computed tomography analysis, but only with modest success. In this report, we aimed to review the available evidence for assessing markers of mechanical LV dyssynchrony by various echocardiographic modalities and their respective strength in predicting favorable response to CRT treatment, comparing global with segmental ones. While the accuracy of segmental markers of dyssynchrony in predicting satisfactory response to CRT remains controversial because of various technical limitations, global markers seem easier to measure, reproducible, and potentially accurate in reflecting overall cavity response and its clinical implications. More studies are needed to qualify this proposal.

The clinical benefits of adding a third dimension to assess the left ventricle with echocardiography

Three-dimensional echocardiography is a novel imaging technique based on acquisition and display of volumetric data sets in the beating heart. This permits a comprehensive evaluation of left ventricular (LV) anatomy and function from a single acquisition and expands the diagnostic possibilities of noninvasive cardiology. It provides the possibility of quantitating geometry and function of LV without preestablished assumptions regarding cardiac chamber shape and allows an echocardiographic assessment of the LV that is less operator-dependent and therefore more reproducible. Further developments and improvements for widespread routine applications include higher spatial and temporal resolution to improve image quality, faster acquisition, processing and reconstruction, and fully automated quantitative analysis. At present, three-dimensional echocardiography complements routine 2DE in clinical practice, overcoming some of its limitations and offering additional valuable information that has led to recommending its use for routine assessment of the LV of patients in whom information about LV size and function is critical for their clinical management.

Electromechanical dyssynchrony and resynchronization of the failing heart

Patients with heart failure and decreased function frequently develop discoordinate contraction because of electric activation delay. Often termed dyssynchrony, this further decreases systolic function and chamber efficiency and worsens morbidity and mortality. In the mid- 1990s, a pacemaker-based treatment termed cardiac resynchronization therapy (CRT) was developed to restore mechanical synchrony by electrically activating both right and left sides of the heart. It is a major therapeutic advance for the new millennium. Acute chamber effects of CRT include increased cardiac output and mechanical efficiency and reduced mitral regurgitation, whereas reduction in chamber volumes ensues more chronically. Patient candidates for CRT have a prolonged QRS duration and discoordinate wall motion, although other factors may also be important because ≈30% of such selected subjects do not respond to the treatment. In contrast to existing pharmacological inotropes, CRT both acutely and chronically increases cardiac systolic function and work, yet it also reduces long-term mortality. Recent studies reveal unique molecular and cellular changes from CRT that may also contribute to this success. Heart failure with dyssynchrony displays decreased myocyte and myofilament function, calcium handling, β-adrenergic responsiveness, mitochondrial ATP synthase activity, cell survival signaling, and other changes. CRT reverses many of these abnormalities often by triggering entirely new pathways. In this review, we discuss chamber, circulatory, and basic myocardial effects of dyssynchrony and CRT in the failing heart, and we highlight new research aiming to better target and implement CRT, as well as leverage its molecular effects.