Left ventricular myocardial deformation pattern, mechanical dispersion, and their relation with electrocardiogram markers in the large population-based STANISLAS cohort: insights into electromechanical coupling

Myocardial strain of the left ventricle by speckle tracking echocardiography: From physics to clinical practice

Speckle tracking echocardiography (STE) is a reliable imaging technique of recognized clinical value in several settings. This method uses the motion of ultrasound backscatter speckles within echocardiographic images to derive myocardial velocities and deformation parameters, providing crucial insights on several cardiac pathological and physiological processes. Its feasibility, reproducibility, and accuracy have been widely demonstrated, being myocardial strain of the various chambers inserted in diagnostic algorithms and guidelines for various pathologies. The most important parameters are Global longitudinal strain (GLS), Left atrium (LA) reservoir strain, and Global Work Index (GWI): based on large studies the average of the lower limit of normality are -16%, 23%, and 1442 mmHg%, respectively. For GWI, it should be pointed out that myocardial work relies primarily on non-invasive measurements of blood pressure and segmental strain, both of which exhibit high variability, and thus, this variability constitutes a significant limitation of this parameter. In this review, we describe the principal aspects of the theory behind the use of myocardial strain, from cardiac mechanics to image acquisition techniques, outlining its limitation, and its principal clinical applications: in particular, GLS have a role in determine subclinical myocardial dysfunction (in cardiomyopathies, cardiotoxicity, target organ damage in ambulatory patients with arterial hypertension) and LA strain in determine the risk of AF, specifically in ambulatory patients with arterial hypertension.

Myocardial electrophysiological and mechanical changes caused by moderate hypothermia-A clinical study

Moderate hypothermia has been used to improve outcomes in comatose out-of-hospital cardiac arrest survivors during the past two decades, although the effects remain controversial. We have recently shown in an experimental study that myocardial electrophysiological and mechanical relationships were altered during moderate hypothermia. Electromechanical window positivity increased, and electrical dispersion of repolarization decreased, both of which are changes associated with decreased arrhythmogenicity in clinical conditions. Mechanical dispersion, a parameter also linked to arrhythmic risk, remained unaltered. Whether corresponding electrophysiological and mechanical changes occur in humans during moderate hypothermia, has not been previously explored. Twenty patients with normal left ventricular function were included. Measurements were obtained at 36 and 32°C prior to ascending aortic repair while on partial cardiopulmonary bypass and at 36°C after repair. Registrations were performed in the presence of both spontaneous and comparable paced heart rate during standardized loading conditions. The following electrical and mechanical parameters were explored: (1) Electromechanical window, measured as time difference between mechanical and electrical systole, (2) dispersion of repolarization from ECG T-wave, and (3) mechanical dispersion, measured as segmental variation in time to peak echocardiographic strain. At moderate hypothermia, mechanical systolic prolongation (425 ± 43-588 ± 67 ms, p < 0.001) exceeded electrical systolic prolongation (397 ± 49-497 ± 79 ms, p < 0.001), whereby, electromechanical window positivity increased (29 ± 30-86 ± 50 ms, p < 0.001). Dispersion of repolarization and mechanical dispersion remained unchanged. Corresponding electrophysiological and mechanical relationships were present at comparable paced heart rates. After rewarming, the increased electromechanical window was reversed in the presence of both spontaneous and paced heart rates. Moderate hypothermia increased electromechanical window positivity, while dispersion of repolarization and mechanical dispersion remained unchanged. This impact of hypothermia may be clinically relevant for selected groups of patients after cardiac arrest.

Early changes in left ventricular myocardial function by 2D speckle tracking layer-specific technique in neonates with hyperbilirubinemia

Background

Hyperbilirubinemia (HBN) can cause myocardial injury in neonates. Advancement in myocardial deformation imaging allows the detection of subclinical changes in myocardial contractility. The present study aimed to evaluate the changes in left ventricular contractility in newborns with hyperbilirubinemia by 2D speckle tracking imaging (STI).

Methods

A group of 134 neonates who reached the diagnostic level of HBN as the HBN group was selected. The control group included 56 healthy newborns. The interventricular septum, anterior partition, anterior wall, sidewall, posterior wall, and inferior wall were separated into the basal, middle, and apical segments. In each segment, speckle tracking analysis was performed in the subintimal, middle, and subadventitial myocardium. The overall longitudinal strain of the myocardium in different ventricular walls and segments and global longitudinal strain (GLS) were computed. At the same time, the laboratory results of blood gas analysis, blood routine tests, liver function, and myocardial enzyme spectrum in HBN neonates were collected and correlated with the left ventricular stratified strain parameters.

Results

The gradient of the left ventricular GLS had the same characteristics in both groups of newborns. There was a decreasing trend of longitudinal strain (LS) from the intima to the adventitia (i.e., GLSendo > GLSmid > GLSepi). This gradient was also present in stratified LS in each myocardial segment (P<0.001). The LS showed an increasing trend from the basal to the apical segment (P<0.001). The LS of the ventricular septum, anterior wall (or anterior septum), inferior wall, lateral wall, and posterior wall showed a decreasing trend (P<0.001). Stratified strain parameters of the ventricular wall (i.e., the 3-layer myocardium: LSendo-SEPT, LSmid-SEPT, and LSepi-SEPT) were all significantly lower in the HBN group than in the control group (P=0.019, P=0.019, and P=0.023, respectively). LSedo-ANT, LSmid-ANT, and LSepi-ANT were also reduced, and the difference between LSendo-ANT and LSepi-ANT was statistically significant. The segmental stratified strain parameters (i.e., the apical 3-layer myocardium: LSepi-a, LSmid-a, and LSepi-a) decreased, and the difference in LSepi-a was statistically significant (P=0.043). Overall strain parameters (i.e., the 3-layer myocardial overall strain: GLSendo, GLSmid, and GLSepi) were reduced, but the difference was not statistically significant (P=0.612, P=0.653, and P=0.585, respectively). The subclinical changes in systolic function in the HBN group, reflected by the parameters of longitudinal myocardial strain, correlate to some extent with multiple results of laboratory tests.

Conclusions

2DSTI stratified strain technology can quantitively evaluate changes in the LS of the left ventricle in different ventricular walls, wall segments, and layers of the myocardium.

OUP accepted manuscript

An abundance of literature describes physiological and pathological determinants of cardiac performance, building on the principles of excitation–contraction coupling. However, the mutual influencing of excitation–contraction and mechano-electrical feedback in the beating heart, here designated ‘electromechanical reciprocity’, remains poorly recognized clinically, despite the awareness that external and cardiac-internal mechanical stimuli can trigger electrical responses and arrhythmia. This review focuses on electromechanical reciprocity in the long-QT syndrome (LQTS), historically considered a purely electrical disease, but now appreciated as paradigmatic for the understanding of mechano-electrical contributions to arrhythmogenesis in this and other cardiac conditions. Electromechanical dispersion in LQTS is characterized by heterogeneously prolonged ventricular repolarization, besides altered contraction duration and relaxation. Mechanical alterations may deviate from what would be expected from global and regional repolarization abnormalities. Pathological repolarization prolongation outlasts mechanical systole in patients with LQTS, yielding a negative electromechanical window (EMW), which is most pronounced in symptomatic patients. The electromechanical window is a superior and independent arrhythmia-risk predictor compared with the heart rate-corrected QT. A negative EMW implies that the ventricle is deformed—by volume loading during the rapid filling phase—when repolarization is still ongoing. This creates a ‘sensitized’ electromechanical substrate, in which inadvertent electrical or mechanical stimuli such as local after-depolarizations, after-contractions, or dyssynchrony can trigger abnormal impulses. Increased sympathetic-nerve activity and pause-dependent potentiation further exaggerate electromechanical heterogeneities, promoting arrhythmogenesis. Unraveling electromechanical reciprocity advances the understanding of arrhythmia formation in various conditions. Real-time image integration of cardiac electrophysiology and mechanics offers new opportunities to address challenges in arrhythmia management.

The year 2020 in the European Heart Journal - Cardiovascular Imaging: part I

The European Heart Journal - Cardiovascular Imaging was launched in 2012 and has during these 9 years become one of the leading multimodality cardiovascular imaging journals. The journal is currently ranked as number 20 among all cardiovascular journals. Our journal is well established as one of the top cardiovascular journals and is the most important cardiovascular imaging journal in Europe. The most important studies published in our Journal in 2020 will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.

Exercise-induced B-lines in heart failure with preserved ejection fraction occur along with diastolic function worsening

Aims

Pulmonary congestion during exercise assessed by lung ultrasound predicts negative outcome in patients with heart failure with preserved ejection fraction (HFpEF). We aimed at assessing predictors of exercise‐induced pulmonary B‐lines in HFpEF patients.

Methods and results

Eighty‐one I–II NYHA class HFpEF patients (65.0  ± 8.2 y/o, 56.8% females) underwent standard and strain echocardiography, lung ultrasound, and natriuretic peptide assessment during supine exercise echocardiography (baseline and peak exercise). Peak values and their changes were compared in subgroups according to exercise lung congestion grading (peak B‐lines >10 or ≤10). Exercise elicited significant changes for all echocardiographic parameters in both subgroups [39/81 (48.1%) with peak B‐lines >10; 42/81 (51.9%) with B‐lines ≤10]. Peak values and changes of E‐wave (and its derived indices) were significantly higher in patients with >10 peak B‐lines compared with those with ≤10 B‐line (all P‐values <0.03), showing significant correlation with peak B‐lines for all parameters; concomitantly, global longitudinal strain (GLS) and global strain rate (GSR) during systole (GSRs), early (GSRe) and late (GSRa) diastole, and isovolumic relaxation (GSRivr) were reduced in patients with B‐lines >10 (all P‐values <0.05), showing a negative correlation with peak B‐lines. By adjusted linear regression analysis, peak and change diastolic parameters (E‐wave, E/e′, GSRivr, and E/GSRivr) and peak GLS were individually significantly associated with peak B‐lines. By covariate‐adjusted multivariable model, E/e′ and GSRa at peak exercise were retained as independent predictors of peak B‐lines, with substantial goodness of fit of model (adjusted R² 0.776).

Conclusions

In HFpEF, development of pulmonary congestion upon exercise is mostly concomitant with exercise‐induced worsening of diastolic function.

Optimal echocardiographic assessment of myocardial dysfunction for arrhythmic risk stratification in phospholamban mutation carriers

Aims 

Phospholamban (PLN) p.Arg14del mutation carriers are at risk of developing malignant ventricular arrhythmias (VAs) and/or heart failure. Currently, left ventricular ejection fraction (LVEF) plays an important role in risk assessment for VA in these individuals. We aimed to study the incremental prognostic value of left ventricular mechanical dispersion (LVMD) by echocardiographic deformation imaging for prediction of sustained VA in PLN p.Arg14del mutation carriers.

Methods and results

We included 243 PLN p.Arg14del mutation carriers, which were classified into three groups according to the ‘45/45’ rule: (i) normal left ventricular (LV) function, defined as preserved LVEF ≥45% with normal LVMD ≤45 ms (n = 139), (ii) mechanical LV dysfunction, defined as preserved LVEF ≥45% with abnormal LVMD >45 ms (n = 63), and (iii) overt LV dysfunction, defined as reduced LVEF <45% (n = 41). During a median follow-up of 3.3 (interquartile range 1.8–6.0) years, sustained VA occurred in 35 individuals. The negative predictive value of having normal LV function at baseline was 99% [95% confidence interval (CI): 92–100%] for developing sustained VA. The positive predictive value of mechanical LV dysfunction was 20% (95% CI: 15–27%). Mechanical LV dysfunction was an independent predictor of sustained VA in multivariable analysis [hazard ratio adjusted for VA history: 20.48 (95% CI: 2.57–162.84)].

Conclusion 

LVMD has incremental prognostic value on top of LVEF in PLN p.Arg14del mutation carriers, particularly in those with preserved LVEF. The ‘45/45’ rule is a practical approach to echocardiographic risk stratification in this challenging group of patients. This approach may also have added value in other diseases where LVEF deterioration is a relative late marker of myocardial dysfunction.

Cardiac Remodeling and Diastolic Dysfunction in Paroxysmal Atrial Fibrillation

Background: Atrial fibrillation (AF) leads to the development of cardiac remodeling/diastolic dysfunction and vice versa. We intended to determine whether cardiac remodeling/diastolic dysfunction is present at early stages of AF. Methods: We studied 175 patients with paroxysmal AF, compared with 175 matched control subjects, who had available echocardiography data to investigate the association between echocardiographic variables and AF from the STANISLAS cohort. Results: In this study (mean age 55 years; 70.3% male), patients with paroxysmal AF had greater left ventricular mass compared to matched controls (p < 0.05). Patients with paroxysmal AF were also likely to have larger left atrial volume and a higher peak tricuspid regurgitation velocity, leading to higher prevalence (though <10% in the AF group) of diastolic dysfunction (all-p < 0.05). Multivariable conditional logistic regression models showed that paroxysmal AF was significantly associated with increased left ventricular mass and left atrial enlargement (all-p < 0.001), but not with e’ and deceleration time of E wave (all-p > 0.1). Conclusions: Left ventricular mass and left atrial enlargement rather than diastolic dysfunction (as evaluated by echocardiography) were associated with paroxysmal AF irrespective of body mass index, blood pressure and renal function. These findings suggest that cardiac remodeling may occur very early in the natural history of AF.

Left ventricular characteristics of noncompaction phenotype patients with good ejection fraction measured with cardiac magnetic resonance

OBJECTIVE

We describe left ventricular (LV) volumes, myocardial and trabeculated muscle mass and strains with Cardiac magnetic resonance of a large cohort (n=81) who fulfilled the morphologic criteria of left ventricular noncompaction (LVNC) and had good ejection fraction (EF >55%) and compare them with healthy controls (n=81). Male and female patients were compared to matched controls and to each other. We also investigated the LV trabeculated muscle mass cutoff in male and female patients with LVNC.

METHODS

81 participants with LVNC and 81 healthy controls were included. Male and female patients were compared to matched controls and to each other. We also investigated the left ventricular trabeculated muscle mass cut-off in male and female LVNC patients.

RESULTS

The LV parameters of the LVNC population were normal, but they had significantly higher volumes, myocardial and trabeculated muscle mass, and a significantly smaller EF than the controls. Similar differences were observed after stratifying by sex. The optimal LV trabeculated muscle mass cutoffs were 25.8 g/m2 in men (area under the curve: 0.81) and 19.0 g/m2 in women (area under the curve: 0.87). The patients had normal global strains but a significantly worse global circumferential strain (patients vs controls: -29.9±4.9 vs. -35.8±4.7%, p<0.05) and significantly higher circumferential mechanical dispersion than the controls (patients vs. controls: 7.6±4.2 vs. 6.1±2.8%; p<0.05). No disease-related strain differences were noted between men and women.

CONCLUSION

The LV functional and strain characteristics of the LVNC cohort differed significantly from those of healthy participants; this might be caused by increased LV trabeculation, and its clinical relevance might be questionable. The LV trabeculated muscle mass was very different between men and women; thus, the use of sex-specific morphologic diagnostic criteria should be considered.

Left Ventricular Remodeling and Myocardial Work: Results From the Population-Based STAAB Cohort Study

Introduction: Left ventricular (LV) dilatation and LV hypertrophy are acknowledged precursors of myocardial dysfunction and ultimately of heart failure, but the implications of abnormal LV geometry on myocardial function are not well-understood. Non-invasive LV myocardial work (MyW) assessment based on echocardiography-derived pressure-strain loops offers the opportunity to study detailed myocardial function in larger cohorts. We aimed to assess the relationship of LV geometry with MyW indices in general population free from heart failure.

Methods and Results: We report cross-sectional baseline data from the Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB) cohort study investigating a representative sample of the general population of Würzburg, Germany, aged 30–79 years. MyW analysis was performed in 1,926 individuals who were in sinus rhythm and free from valvular disease (49.3% female, 54 ± 12 years). In multivariable regression, higher LV volume was associated with higher global wasted work (GWW) (+0.5 mmHg% per mL/m², p < 0.001) and lower global work efficiency (GWE) (−0.02% per mL/m², p < 0.01), while higher LV mass was associated with higher GWW (+0.45 mmHg% per g/m², p < 0.001) and global constructive work (GCW) (+2.05 mmHg% per g/m², p < 0.01) and lower GWE (−0.015% per g/m², p < 0.001). This was dominated by the blood pressure level and also observed in participants with normal LV geometry and concomitant hypertension.

Conclusion: Abnormal LV geometric profiles were associated with a higher amount of wasted work, which translated into reduced work efficiency. The pattern of a disproportionate increase in GWW with higher LV mass might be an early sign of hypertensive heart disease.

Echocardiographic deformation imaging unmasks global and regional mechanical dysfunction in patients with idiopathic ventricular fibrillation: A multicenter case-control study

BACKGROUND

Idiopathic ventricular fibrillation (IVF) is diagnosed in patients with sudden onset of ventricular fibrillation of unidentified origin. New diagnostic tools that can detect subtle abnormalities are needed to diagnose and treat patients with an underlying substrate.

OBJECTIVE

The purpose of this study was to explore echocardiographic deformation characteristics in IVF patients.

METHODS

Echocardiograms were analyzed with deformation imaging by 2-dimensional speckle tracking. Global and regional measurements of the left ventricle (LV) and right ventricle (RV) were performed. Regional LV deformation patterns were evaluated for the presence of postsystolic shortening. Regional RV deformation patterns were classified as type I (normal) or type II/III (abnormal).

RESULTS

In total, 47 IVF patients (mean age 45 years; left ventricular ejection fraction [LVEF] 56%) and 47 healthy controls (mean age 41 years; LVEF 60%) were included. IVF patients showed more global deformation abnormalities as indicated by lower LV global longitudinal strain (18.5% ± 2.6% vs 21.6% ± 1.8%; P <.001) and higher LV mechanical dispersion (41 ± 12 ms vs 26 ± 6 ms; P <.001). In addition, IVF patients showed more regional LV postsystolic shortening compared to healthy controls (50% vs 11%; P <.001). Abnormal RV deformation patterns were observed in 16% of IVF patients and in none of the control subjects (P <.001).

CONCLUSION

We were able to show both regional and global echocardiographic deformation abnormalities in IVF patients. This study provides evidence that localized myocardial disease is present in a subset of IVF patients.

The year 2019 in the European Heart Journal-Cardiovascular Imaging: Part I

The European Heart Journal-Cardiovascular Imaging was launched in 2012 and has during these years become one of the leading multimodality cardiovascular imaging journals. The journal is now established as one of the top cardiovascular journals and is the most important cardiovascular imaging journal in Europe. The most important studies published in our Journal in 2019 will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.