The non-invasive assessment of myocardial work by pressure-strain analysis: clinical applications

Assessment of cardiopulmonary capacity in deconditioned athletes because of knee injury

BACKGROUND

An athlete's career inevitably goes through periods of forced physical exercise interruption like a knee injury. Advanced echocardiographic methods and cardiopulmonary exercise testing (CPET) are essential in evaluating athletes in the period elapsing after the injury. However, the feasibility of a maximal pre-surgery CPET and the capacity of resting advanced echocardiographic techniques to predict cardiorespiratory capacity still need to be clarified.

METHODS

We evaluated 28 non-professional athletes aged 18-52, involved in prevalently aerobic or alternate aerobic/anaerobic sports activities, affected by a knee pathology with indications for surgical treatment. The evaluation was performed at rest by trans-thoracic echocardiography, including global longitudinal strain (GLS) and myocardial work (MW) assessment, and during exercise by CPET.

RESULTS

The percent-predicted peak oxygen consumption (peak VO2%) was 82.8±13.7%, the mean respiratory exchange ratio was 1.16±0.08, and the mean ventilation/carbon dioxide (VE/VCO2) slope was 24.23±3.36. Peak VO2% negatively correlated with GLS (r=-0.518, P=0.003) and global wasted work (GWW) (r =-0.441, P=0.015) and positively correlated with global work efficiency (GWE) (r=0.455, P=0.012). Finally, we found that the VE/VCO2 slope during exercise was negatively correlated with GWE (r=-0.585, P=0.001) and positively correlated with GWW (r=0.499, P=0.005).

CONCLUSIONS

A maximal CPET can be obtained in deconditioned athletes because of a knee injury, allowing a comprehensive functional pre-surgery evaluation. In these patients, peak VO2 is reduced due to decreased physical activity after injury; however, a lower cardiopulmonary efficiency may be a concause of the injury itself. In addition, we demonstrated that the MW indexes obtained at rest could predict exercise capacity and ventilatory efficiency as evaluated by CPET.

Myocardial Work Indices Predict Hospitalization in Patients with Advanced Heart Failure

BACKGROUND

An increasing proportion of heart failure (HF) patients progress to the advanced stage (AdHF) with high event rates and limited treatment options. Echocardiography, particularly Speckle Tracking-derived myocardial work (MW), is useful for HF diagnosis and prognosis. We aimed to assess MW's feasibility in the prognostic stratification of AdHF.

METHODS

We retrospectively screened patients with AdHF who accessed our hospital in 2018-2022. We excluded subjects with inadequate acoustic windows; unavailable brachial artery cuff pressure at the time of the echocardiography; atrial fibrillation; and mitral or aortic regurgitation. We measured standard parameters and left ventricular (LV) strain (LS) and MW. The population was followed up to determine the composite outcomes of all-cause mortality, left ventricular assist device implantation and heart transplantation (primary endpoint), as well as unplanned HF hospitalization (secondary endpoint).

RESULTS

We enrolled 138 patients, prevalently males (79.7%), with a median age of 58 years (IQR 50-62). AdHF etiology was predominantly non-ischemic (65.9%). Thirty-five patients developed a composite event during a median follow-up of 636 days (IQR 323-868). Diastolic function, pulmonary pressures, and LV GLS and LV MW indices were not associated with major events. Contrarily, for the secondary endpoint, the hazard ratio for each increase in global work index (GWI) by 50 mmHg% was 0.90 (p = 0.025) and for each increase in global constructive work (GCW) by 50 mmHg% was 0.90 (p = 0.022). Kaplan-Meier demonstrated better endpoint-free survival, with an LV GWI ≥ 369 mmHg%.

CONCLUSIONS

GWI and GCW, with good feasibility, can help in the better characterization of patients with AdHF at higher risk of HF hospitalization and adverse events, identifying the need for closer follow-up or additional HF therapy.

A novel method for the evaluation of right ventricular dysfunction in acute pulmonary embolism: Myocardial work indices

PURPOSE

The presence of right ventricular dysfunction indicates a higher risk status in patients with pulmonary embolism (PE). The RV strain evaluated by speckle-tracking echocardiography seems to be more reliable method in the evaluation of RV dysfunction as compared to standard echocardiographic measures. In this study, we aimed to determine the value of myocardial-work indices in evaluating serial changes of RV function in acute PE.

METHODS

Our study comprised 83 consecutive acute PE patients who admitted to our tertiary cardiovascular hospital. Echocardiography was performed within the first 24-hours of hospitalization, and RV and LV myocardial-work parameters were obtained along with standard echocardiographic parameters. The change in the RV/LVr detected on tomography was selected as the primary outcome measure, and its' predictors were analyzed with classical linear regression and a generalized additive model (GAM).

RESULTS

Among the LV-RV strain and myocardial work parameters, the RV global longitudinal strain (GLS) has borderline statistical significance in predicting the RV/LVr change whereas the RV global work efficiency (RV-GWE) strongly predicted RV/LVr change (p: 0.049 and <0.001, respectively).

CONCLUSION

In this study, classical linear regression and GAM analyses showed that RV-GWE seems to offer a better prediction of RV/LVr change in patients with acute PE.

Myocardial work and left heart deformation parameters across primary mitral regurgitation severity

AIMS

Myocardial work (MW) estimation by pressure-strain loops using speckle tracking echocardiography (STE) has shown to evaluate left ventricular (LV) contraction overcoming the load-dependency limit of LV global longitudinal strain (GLS). This has proved useful in hemodynamic variation settings e.g. heart failure and valvular heart disease. However, the variation of MW and strain parameters across different stages of primary mitral regurgitation (MR) and its impact on symptoms, which was the aim of our study, has never been investigated.

METHODS AND RESULTS

Consecutive patients with mild, moderate and severe MR were prospectively enrolled. Exclusion criteria were: chronic atrial fibrillation, valvular heart prosthesis, previous cardiac surgery. Clinical evaluation, blood sample tests, ECG and echocardiography with STE and MW measurement were performed. Patients were then divided into groups according to MR severity. Differences among the groups and predictors of symptoms (as NYHA class≥2) were explored as study endpoints. Overall, 180 patients were enrolled (60 mild,60 moderate,60 severe MR). LV GLS and global peak atrial longitudinal strain (PALS) reduced according to MR severity. Global constructive work (GCW) and global wasted work (GWW) significantly improved, while global work efficiency (GWE) reduced, in patients with moderate and severe MR. Among echocardiographic parameters, global PALS emerged as the best predictor of NYHA class (p < 0.001;area under curve,AUC = 0.7).

CONCLUSIONS

MW parameters accurately describe the pathophysiology of MR, with initial attempt of LV increased contractility to compensate volume overload parallel to the disease progress, although with low efficacy, while global PALS is the most associated with the burden of MR symptoms.

Anthracycline-induced cardiotoxicity on regional myocardial work and left ventricular mechanical dispersion in adolescents and young adults in post-lymphoma remission

BACKGROUND

Myocardial work (MW) is a new echocardiographic tool with a high sensitivity to detect early and subtle alterations of myocardial function. We aimed to evaluate the late effects of anthracyclines by assessing the global and segmental MW and intraventricular mechanical dispersion from speckle tracking echocardiography in childhood lymphoma survivors (CLS).

METHODS

Thirty-one young adults including CLS and age-matched healthy controls were enrolled. All underwent echocardiography including an evaluation of left ventricular (LV) morphology and regional function. We assessed LV longitudinal (differentiating sub-endocardial and sub-epicardial layers), circumferential strains and twist, global and regional MW index (MWI). LV mechanical dispersion was assessed from the time dispersion of LV longitudinal strain, from myocardial wasted work (MWW) and myocardial work efficiency (MWE).

RESULTS

The longitudinal strains both at the level of the sub-endocardium and sub-epicardium were reduced in CLS compared to controls. The global MWI was also decreased (1668 ± 266 vs 1870 ± 264%.mmHg in CLS patients and controls, respectively, p < 0.05), especially on the apical segments. An increase of LV intraventricular mechanical dispersion was observed in CLS. MWW and MWE remained unchanged compared to controls.

CONCLUSION

Our results strongly support that cardiac remodeling is observed in CLS, characterized by a decrease in MW and an increase in LV mechanical dispersion. The apex is specifically altered, but its clinical significance remains uncertain. MW as a complement to strain seems interesting in cancer survivors to detect myocardial dysfunction at early stage and adapt their follow-up.

Echocardiographic Myocardial Work: A Novel Method to Assess Left Ventricular Function in Patients with Coronary Artery Disease and Diabetes Mellitus

Myocardial ischemia caused by coronary artery disease (CAD) and the presence of metabolic abnormalities and microvascular impairments detected in patients with diabetes mellitus (DM) are a common cause of left ventricular (LV) dysfunction. Transthoracic echocardiography is the most-used, non-invasive imaging method for the assessment of myocardial contractility. The accurate evaluation of LV function is crucial for identifying patients who are at high risk or may have worse outcomes. Myocardial work (MW) is emerging as an alternative tool for the evaluation of LV systolic function, providing additional information on cardiac performance when compared to conventional parameters such as left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) because it incorporates deformation and load into its analysis. The potential of MW in various conditions is promising and it has gained increased attention. However, larger studies are necessary to further investigate its role and application before giving an answer to the question of whether it can have widespread implementation into clinical practice. The aim of this review is to summarize the actual knowledge of MW for the analysis of LV dysfunction caused by myocardial ischemia and hyperglycemia.

Global constructive work is associated with ventricular arrhythmias after cardiac resynchronization therapy

AIMS

Non-invasive left ventricular (LV) pressure-strain loops provide a novel method for quantifying myocardial work by incorporating LV pressure in measurements of myocardial deformation. Early studies suggest that myocardial work parameters such as global constructive work (GCW) could be useful and reliable in arrhythmia prediction, particularly in patients undergoing cardiac resynchronization therapy (CRT). The aim of this study was to evaluate whether the magnitude of GCW was associated with the occurrence of ventricular arrhythmias in patients after CRT.

METHODS AND RESULTS

Patients on guideline-recommended treatment with a CRT defibrillator (CRT-D) were evaluated by 2D speckle-tracking echocardiography including measurements of GCW at least 6 months after implantation. The primary outcome was a composite of appropriate defibrillator therapy and sustained ventricular arrhythmia under the monitor zone. A total of 162 patients [mean age 66 years (±10), 122 males (75%)] were included. Sixteen (10%) patients experienced the primary outcome during a median follow-up of 18 months (interquartile range: 12-25) after the performance of index echocardiography. Patients with a below-median GCW (<1473 mmHg%) had a hazard ratio (HR) for the outcome of 8.14 [95% confidence interval (CI): 1.83-36.08], P = 0.006 compared with patients above the median in a univariate model and remained an independent predictor after multivariate adjustment for the estimated glomerular filtration rate and QRS duration [HR 4.75 (95% CI: 1.01-22.28), P < 0.05].

CONCLUSION

In patients treated with CRT-D, a GCW below median level was associated with a five-fold increase in the risk of ventricular arrhythmias.

Myocardial Work Appraisal in Transthyretin Cardiac Amyloidosis and Nonobstructive Hypertrophic Cardiomyopathy

Global left ventricular (LV) myocardial work (MW) indexes can be recognized at ultrasound imaging from the LV pressure/global longitudinal strain (GLS) loop analysis. A total of 4 indexes, global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE), have been demonstrated to overcome the methodological limitations of GLS and provide useful information on myocardial dysfunction in some clinical settings. Although impaired MW indexes have been demonstrated in patients with transthyretin cardiac amyloidosis (ATTR) or with nonobstructive hypertrophic cardiomyopathy (HCM), there are no comparative studies at present. This study aimed to describe the characteristics of MW in both these clinical settings compared with patients with well-controlled hypertension (HTN). A total of 83 patients, 32 with ATTR (aged 70 ± 11 years, 32% mutated, 68% wild-type, 72% men), 29 with HCM (aged 57 ± 17 years), and 22 HTN controls (aged 56 ± 5.6 years, 59% men) were prospectively enrolled at 2 clinical centers. All participants had New York Heart Association class I or II. Overall, the LV mass index was greater in both study groups than in HTN, whereas the LV ejection fraction (EF) was significantly lower in ATTR compared with other groups. Based on this finding, patients with ATTR were further divided into 2 subgroups: ATTR1 (LVEF ≤0.50), n = 14 (44%) and ATTR2 (LVEF >0.50), n = 18 (56%). Overall, the GWI and GCW were lower in all ATTR patients (mostly in ATTR1) than in the other groups (p <0.001), whereas only small differences in GWE and none in GWW were found among the groups. Of interest, the pairwise comparison and receiver operating characteristic analysis in preserved LVEF patients showed that GWI was a better discriminator of ATTR2 from HCM patients than GLS, with the cut-off value ≤1,419 mm Hg% (89% sensitivity; 55% specificity; p = 0.013). In conclusion, MW analysis was confirmed to be a modern way to investigate myocardial function in patients with hypertrophic phenocopies. GWI and GCW were more impaired in patients with ATTR compared with HCM and HTN controls. Furthermore, this study likely revealed an additional discriminative value of GWI over GLS alone in preserved LVEF settings.

Left Ventricular Systolic Function After 3 Months of SGLT2 Inhibitor Therapy in Heart Failure Patients with Reduced Ejection Fraction

Not much is known about the effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on echocardiographic parameters of left ventricular (LV) systolic function in patients with heart failure and reduced ejection fraction (HFrEF).We prospectively included 59 outpatients with HFrEF: 41 patients received SGLT2i with OMT (SGLT2i+ group), whereas eighteen patients received OMT without SGLT2i (SGLT2i- group). Myocardial work index (MWI), 3D ejection fraction (3D LVEF), and global longitudinal strain (GLS) were measured at baseline and after 3 months following treatment. At 3-month follow-up, the SGLT2i+ group showed significantly greater improvement in MWI than the SGLT2i- group. In both groups, there was a significant improvement in 3D LVEF and LV GLS, circulating NT-proBNP levels, and NYHA functional class, with significantly greater improvement in the SGLT2i+ group.In conclusion, the addition of SGLT2i to fully optimized background medical therapy resulted in a greater improvement of LV systolic function among outpatients with HFrEF.

Assessment of left ventricular function in patients with type 2 diabetes mellitus by non-invasive myocardial work

Background

Diabetes mellitus (DM) is a chronic disease that poses a serious risk of cardiovascular diseases. Therefore, early detection of impaired cardiac function with non-invasive myocardial imaging is critical for improving the prognosis of patients with DM.

Purpose

This study aimed to assess the left ventricular (LV) function in patients with type 2 diabetes mellitus (T2DM) by non-invasive myocardial work technique.

Materials and methods

In all, 67 patients with T2DM and 28 healthy controls were included and divided into a DM group and a control group. Two-dimensional dynamic images of apical three-chamber view, apical two-chamber view, and apical four-chamber view were collected from all subjects, consisting of at least three cardiac cycles. LV myocardial strain parameters, including global longitudinal strain (GLS) and peak strain dispersion (PSD), as well as myocardial work parameters, including global constructive work (GCW), global wasted work (GWW), global work index (GWI), and global work efficiency (GWE), were obtained and analyzed.

Results

A total of 15 subjects were randomly selected to assess intra-observer and inter-observer consistency of myocardial work parameters and strain parameters, which showed excellent results (intra-class correlation coefficients: 0.856 - 0.983, P<0.001). Compared with the control group, the DM group showed significantly higher PSD (37.59 ± 17.18 ms vs. 27.72 ± 13.52 ms, P<0.05) and GWW (63.98 ± 43.63 mmHg% vs. 39.28 ± 25.67 mmHg%, P<0.05), and lower GWE (96.38 ± 2.02% vs. 97.72 ± 0.98%, P<0.001). Furthermore, the PSD was positively correlated with GWW (r = 0.565, P<0.001) and negatively correlated with GWE (r = -0.569, P<0.001).

Conclusion

Uncoordinated LV myocardial strain, higher GWW, and lower GWE in patients with T2DM may serve as indicators for the early assessment of cardiac impairment in T2DM.

Biventricular cardiac power reserve in heart failure with preserved ejection fraction

AIMS

Cardiac and extracardiac abnormalities play important roles in heart failure with preserved ejection fraction (HFpEF). Biventricular cardiac power output (BCPO) quantifies the total rate of hydraulic work performed by both ventricles, suggesting that it may help to identify patients with HFpEF and more severe cardiac impairments to better individualize treatment.

METHODS AND RESULTS

Patients with HFpEF (n = 398) underwent comprehensive echocardiography and invasive cardiopulmonary exercise testing. Patients were categorized as low BCPO reserve (n = 199, < median of 1.57 W) or preserved BCPO reserve (n = 199). As compared to those with preserved BCPO reserve, those with low reserve were older and leaner, with more atrial fibrillation, higher N-terminal pro-B-type natriuretic peptide levels, worse renal function, more impaired left ventricular (LV) global longitudinal strain, worse LV diastolic function and right ventricular longitudinal function. Cardiac filling pressures and pulmonary artery pressures at rest were higher in low BCPO reserve, but central pressures were similar during exercise to those with preserved BCPO reserve. Exertional systemic and pulmonary vascular resistances were higher and exercise capacity was more impaired in those with low BCPO reserve. Reduced BCPO reserve was associated with increased risk for the composite endpoint of heart failure hospitalization or death over 2.9 (interquartile range 0.9-4.5) years of follow-up (hazard ratio 2.77, 95% confidence interval 1.73-4.42, p < 0.0001).

CONCLUSIONS

Inability to enhance BCPO during exercise is associated with more advanced HFpEF, increased systemic and pulmonary vascular resistance, reduced exercise capacity and increased adverse events in patients with HFpEF. Novel therapies that enhance biventricular reserve merit further investigation for patients with this phenotype.

Mitral and Tricuspid Valve Disease in Athletes

Observing mitral or tricuspid valve disease in an athlete raises many considerations for the clinician. Initially, the etiology must be clarified, with causes differing depending on whether the athlete is young or a master. Notably, vigorous training in competitive athletes leads to a constellation of structural and functional adaptations involving cardiac chambers and atrioventricular valve systems. In addition, a proper evaluation of the athlete with valve disease is necessary to evaluate the eligibility for competitive sports and identify those requiring more follow-up. Indeed, some valve pathologies are associated with an increased risk of severe arrhythmias and potentially sudden cardiac death. Traditional and advanced imaging modalities help clarify clinical doubts, allowing essential information about the athlete's physiology and differentiating between primary valve diseases from those secondary to training-related cardiac adaptations. Remarkably, another application of multimodality imaging is evaluating athletes with valve diseases during exercise to reproduce the sport setting and better characterize the etiology and valve defect mechanism. This review aims to analyze the possible causes of atrioventricular valve diseases in athletes, focusing primarily on imaging applications in diagnosis and risk stratification.

Effects of continuous positive airway pressure therapy on left ventricular performance in patients with severe obstructive sleep apnea

We investigated myocardial performance concerning obstructive sleep apnea (OSA) severity and the benefits of continuous positive airway pressure (CPAP) therapy. In this randomized sham-controlled trial, 52 patients (mean age, 49 years; 92%, males; mean AHI, 59) with severe OSA were randomly assigned to receive either CPAP or sham treatment for 3 months. The severity of OSA was determined using the apnea/hypopnea index (AHI), oxygen desaturation index (ODI), percentage of sleep time below 90% oxygen saturation (T90), and average O₂ saturation during sleep (mean SpO₂). We compared the changes in myocardial work after 3 months of CPAP (n = 26) versus the sham group (n = 26) at rest and during an exercise stress test. Unlike AHI or ODI, indices of hypoxemia including T90 and mean SpO₂ were significantly correlated with global constructive work, as defined by work of left ventricle (LV) that contributes to LV ejection during systole (T90, β = 0.393, p = 0.012; mean SpO₂, β = 0.331, p = 0.048), and global wasted work (GWW), as defined by work of LV that does not contribute to LV ejection (T90, β = 0.363, p = 0.015; mean SpO₂, β =  - 0.370, p = 0.019). After 3 months, GWW decreased (80.0 ± 49.2 to 60.8 ± 26.3, p = 0.009) and global work efficiency increased (94.0 ± 4.5 to 95.7 ± 2.0, p = 0.008) in the CPAP group compared to those in the sham group. At the 3-month follow-up exercise stress echocardiography, worsening of GWW during exercise was significantly decreased in the CPAP group compared to that in the sham group (p = 0.045 at 50 W). Hypoxemia indices were closely associated with myocardial performance in patients with severe OSA. CPAP treatment for 3 months improved left ventricular myocardial performance by decreasing wasted work and increasing work efficacy compared to the sham treatment.

Which is the best Myocardial Work index for the prediction of coronary artery disease? A data meta-analysis

BACKGROUND

Early diagnosis of Coronary Artery Disease (CAD) plays a key role to prevent adverse cardiac events such as myocardial infarction and Left Ventricular (LV) dysfunction. Myocardial Work (MW) indices derived from echocardiographic speckle tracking data in combination with non-invasive blood pressure recordings seems promising to predict CAD even in the absence of impairments of standard echocardiographic parameters. Our aim was to compare the diagnostic accuracy of MW indices to predict CAD and to assess intra- and inter-observer variability of MW through a meta-analysis.

METHODS

Electronic databases were searched for observational studies evaluating the MW indices diagnostic accuracy for predicting CAD and intra- and inter-observer variability of MW indices. Pooled sensitivity, specificity, and Summary Receiver Operating Characteristic (SROC) curves were assessed.

RESULTS

Five studies enrolling 501 patients met inclusion criteria. Global Constructive Work (GCW) had the best pooled sensitivity (89%) followed by GLS (84%), Global Work Index (GWI) (82%), Global Work Efficiency (GWE) (80%), and Global Wasted Work (GWW) (75%). GWE had the best pooled specificity (78%) followed by GWI (75%), GCW (70%), GLS (68%), and GWW (61%). GCW had the best accuracy according to SROC curves, with an area under the curve of 0.86 compared to 0.84 for GWI, 0.83 for GWE, 0.79 for GLS, and 0.74 for GWW. All MW indices had an excellent intra- and inter-observer variability.

CONCLUSIONS

GCW is the best MW index proving best diagnostic accuracy in the prediction of CAD with an excellent reproducibility.

Impact of echocardiographic analyses of valvular event timing on myocardial work indices

AIMS

Valvular event timing is an integral part of echocardiographic pressure-strain loop (PSL) analyses. The impact that different event timing modalities may have on myocardial work indices is unknown.

METHODS AND RESULTS

A methodological study was performed on 200 subjects, including 50 healthy subjects, 50 with aortic valve sclerosis, 50 with atrial fibrillation, and 50 with reduced left ventricular ejection fraction. Valvular event timing was estimated by visual assessment, spectral Doppler, and colour tissue Doppler imaging (TDI) M-mode. These valvular event timings were added to the same PSL analyses sequentially to acquire myocardial work indices, including global work index (GWI). For the 200 participants, the median age was 72 years, 50% were men, and mean blood pressure was 143/80 mmHg. Valvular event timings differed between all three modalities and so did all myocardial work indices. Compared with visual assessment, spectral Doppler resulted in a significantly higher GWI (mean difference: 114 ± 93 mmHg%, P < 0.001), and so did TDI (mean difference: 83 ± 90 mmHg%, P < 0.001). A higher GWI by spectral Doppler than by TDI was also observed (mean difference: 30 ± 53 mmHg%, P < 0.001). In the healthy subgroup, a systematic bias was observed for spectral Doppler compared with visual assessment (mean difference: 160 ± 77 mmHg%, P < 0.001), and a similar trend was noted for TDI vs. visual assessment (mean difference: 124 ± 74 mmHg%, P < 0.001).

CONCLUSION

Myocardial work indices differ depending on the event timing modality used, with visual assessment yielding lower GWI values compared with Doppler-based methods. Serial PSL analyses should apply the same event timing method.

Intraoperative Noninvasive Left Ventricular Myocardial Work Indices in Patients Undergoing On-Pump Coronary Artery Bypass Surgery

OBJECTIVES

Noninvasive echocardiographic analysis of left ventricular (LV) myocardial work (MW) enables insights into cardiac mechanics, contractility, and efficacy beyond ejection fraction (EF) and global longitudinal strain (GLS). However, there are limited perioperative data on patients undergoing coronary artery bypass graft (CABG) surgery. The authors aimed to describe the feasibility and the intraoperative course of this novel assessment tool of ventricular function in these patients, and compare it to conventional 2-dimensional (2D) and 3-dimensional (3D) echocardiographic parameters and strain analysis.

DESIGN

A prospective observational study.

SETTING

At a single university hospital.

PARTICIPANTS

Twenty-five patients with preoperative preserved LV and right ventricular function, sinus rhythm, without significant heart valve disease or pulmonary hypertension, and an uncomplicated intraoperative course scheduled for isolated on-pump CABG surgery.

INTERVENTIONS

Transesophageal echocardiography (TEE) was performed intraoperatively after the induction of anesthesia (T1), after termination of cardiopulmonary bypass (T2), and after sternal closure (T3). All measurements were performed under stable hemodynamic conditions, in sinus rhythm or atrial pacing, and vasopressor support with norepinephrine ≤ 0.1 µg/kg/min.

MEASUREMENTS AND MAIN RESULTS

The EchoPAC v204 software (GE Vingmed Ultrasound AS, Norway) was used for analysis of 2D and 3D LVEF, LV GLS, LV global work index (GWI), LV global constructive work (GCW), LV global wasted work (GWW), and LV global work efficiency (GWE). The MW analysis was feasible in all patients. Although there was no significant difference in the values of 2D and 3D EF during the intraoperative interval, GLS deteriorated significantly after CABG compared to assessment after induction of anesthesia (T1 v T2, -13.3 ± 3.0% v -11.6 ± 3.1%; p = 0.012). The GWI declined significantly after surgery (T1 v T2, 1,224 ± 312 mmHg% v 940 ± 267 mmHg%; p < 0.001), as well as GCW (T1 v T2, 1,460 ± 312 mmHg% v 1,244 ± 336 mmHg%; p = 0.005). The GWW increased after CABG (T1 v T2, 143 mmHg% (IQR 99-183) v 251 mmHg% (IQR 179-361); p < 0.001), and GWE decreased (T1 v T2, 89% (IQR 85-92) v 80% (IQR 75-87); p < 0.001). There were no significant changes in the values of 2D and 3D EF, GLS, GWI, GCW, GWW, and GWE before and after sternal closure (T2 v T3).

CONCLUSION

The intraoperative analysis of noninvasive echocardiographically-assessed LV MW indices is feasible. In the short-term period after uncomplicated on-pump CABG, GLS, as well as global and constructive MW, decreased, whereas wasted work increased, resulting in a less efficient left ventricle. None of these aspects was detected by conventional echocardiographic parameters. Therefore, strain and MW analysis might be more sensitive parameters in detecting myocardial dysfunction by TEE in the perioperative setting, adding information on perioperative cardiac energetics.

A noninvasive method of estimating patient-specific left ventricular pressure waveform

BACKGROUND AND OBJECTIVE

The left ventricular pressure waveform is indispensable for the construction of the pressure strain loop when investigating coronary artery disease (CAD) patients. In previous studies by others, exclusion of CAD patients has not allowed a reliable estimation of the left ventricular pressure waveform from the pressure strain loop of these patients. To remedy this, we propose a patient-specific noninvasive method for the estimation of left ventricular pressure.

METHODS

A simplified systemic circulation model consisting primarily of a single fiber model and a 1D simulation of the arterial tree was used. Sensitivity analysis based on the Morris method was performed to select a subset of the important parameters. Following this, the important parameter subset and the set of all the parameters were identified in the model using the pressure waveform of a peripheral artery as input, in a two-step process. In addition, the left ventricular pressure waveform was estimated using the set of all parameters.

RESULTS

Reducing the size of the parameter subset significantly decreases the computational cost of parameter optimization in the first step and greatly simplifies the identification of the full parameter set in the second step. Comparison with the reference left ventricular pressure waveform from CAD patients, showed that the proposed method provides a good estimate of the reference left ventricular pressure waveform. The correlation coefficients between the estimated and reference were r = 0.907, r = 0.904 and r = 0.780 for systolic blood pressure, pulse pressure and mean blood pressure, respectively.

CONCLUSIONS

This work may provide a convenient surrogate for the estimation of the left ventricular pressure waveform.

Effects of postsystolic shortening and diastolic dyssynchrony on myocardial work in untreated early hypertension patients

OBJECTIVES

Myocardial work is estimated from noninvasive pressure-strain loop for advanced assessment of left ventricular function. Postsystolic shortening and diastolic dyssynchrony of left ventricle were noted early in hypertension. Their novel effects on myocardial work will be illustrated in this study.

METHODS

We recruited 43 newly diagnosed hypertensive patients (mean age 51.3 ± 12.5 years, 55.8% men) and 32 age-matched and sex-matched healthy individuals (mean age 52.7 ± 10.5 years, 37.5% men) as control. Pressure-strain loop derived myocardial work incorporated global longitudinal strain from speckle tracking echocardiography with brachial artery cuff pressure. Postsystolic strain index (PSI) was defined by the percentage of postsystolic shortening over peak strain. Diastolic dyssynchrony was assessed by standard deviation of time to peak early diastolic strain rate (TDSr-SD) of 18 segments, and maximal difference of time to peak early diastolic strain rate (TDSr-MD) between any two segments.

RESULTS

After multivariate regression analysis, global myocardial work index (GWI) was independently correlated with TDSr-SD (B = -0.498, P = 0.001) and TDSr-MD (B = -0.513, P = 0.001). Global myocardial constructive work (GCW) was independently correlated with TDSr-SD (B = -0.334, P = 0.025) and TDSr-MD (B = -0.397, P = 0.007). Global myocardial wasted work (GWW) was independently correlated with PSI (B = 0.358, P = 0.019). Global myocardial work efficiency (GWE) was lower in hypertensive patients than healthy control (P = 0.001). The untreated hypertensive patients were different from the healthy individuals with higher TDSr-SD, TDSr-MD, GWI, GCW, GWW, and PSI (all P < 0.05).

CONCLUSION

In conclusion, the effect of diastolic dyssynchrony mainly influenced constructive work, whereas postsystolic shortening affected wasted work in early untreated hypertension.

Reference Values of Noninvasive Myocardial Work Indices Measured by Echocardiography in Healthy Children

BACKGROUD

Noninvasive myocardial work, estimated by left ventricular (LV) pressure-strain loop (PSL), has been introduced for assessing LV myocardial performance. Based on both blood pressure and speckle-tracking derived strain data, noninvasive myocardial work is considered to be less load-dependent than global longitudinal strain (GLS). In some conditions, such as hypertension or aortic coarctation, the increased afterload will affect strain measurements, and myocardial work can serve as a more robust metric.

OBJECTIVE

We prospectively recruited healthy children to explore the relationship between myocardial work indices and body size parameters, and to determine the reference values of noninvasive myocardial work indices in healthy children.

METHODS

183 healthy children (aged 1-18 years, males: 52.5%) were enrolled in the study. Global work index (GWI), global constructive work (GCW), global wasted work (GWW), global work efficiency (GWE), were assessed by LVPSL and compared according to age and sex.

RESULTS

The mean for GWI was 1,448.7 ± 265.0 mm Hg%, 1,859.8 ± 290.7 mm Hg% for GCW, and the median (interquartile range) for GWW was 54.0 (33.0-82.0) mm Hg% and 97.0 (95.0-99.0) % for GWE. male had greater GWI and GCW) than female (1,572.5 ± 250.2 mm Hg% vs. 1,312.2 ± 208.7 mm Hg% and 1,944.3 ± 299.2 mm Hg% vs. 1,766.6 ± 251.5 mm Hg%, respectively, all P < 0.001). GWI and GCW were significantly correlated with baseline parameters, including age, height, weight, BSA, body mass index, heart rate, and blood pressure. After indexed to BSA, GWI (BSA), GCW (BSA) remained significantly negatively correlated with age (P < 0.001).

CONCLUSIONS

we proposed the normal reference values and regression equations for GWI and GCW based on age and BSA in healthy children. This might provide a basis of reference for the evaluation of cardiac function in children with cardiopulmonary disease.

[Evaluation of the effectiveness of the chronic heart failure therapy using the device cardiac contractility modulation according to the new non-invasive method of the myocardium work analysis]

Aim      To analyze echocardiographic parameters that reflect left ventricular (LV) myocardial contractility, using a novel method for evaluation of myocardial performance in patients with chronic heart failure (CHF) and atrial fibrillation (AF) during heart contractility modulation (HCM).Material and methods  Standard echocardiographic parameters and indexes of myocardial strain and work were analyzed for 66 patients (52 men and 14 women; median age, 60 [54; 66] years). 36 patients had paroxysmal AF and 30 patients had permanent AF. All patients had CHF with a duration of 17 [4; 60] months; duration of AF was 12 [6; 36] months. At baseline, the left ventricular ejection fraction (LV EF) was 33 [27; 37] %.Results After one year of HCM, LV EF significantly increased from 33 [27; 37] to 38 [33; 44] % (р=0.001). Also, there were improvements in the myocardial global longitudinal strain (from -6.00 [ - 8; - 4] to -8 [ - 10; - 6] %; р=0.001) and parameters of myocardial work, including the global work efficiency (from 74 [65; 79] to 80 [73; 87] mm Hg%; р=0.001), global constructive work (from 699 [516; 940] to 882 [714; 1242] mm Hg%; р=0.001), and global myocardial work index (from 460 [339; 723] to 668 [497; 943] mm Hg%; р=0.001). A segmentary analysis of LV work parameters showed positive changes in the myocardial constructive work in the area of the interventricular septal apical segment (at baseline, 844 [614; 1224]; after HCM, 1027 [800; 1520] mm Hg%; р=0.05) and the medium segment of the LV anteroseptal wall (at baseline, 593 [312; 1000]; after HCM, 877 [494; 1145] mm Hg%; р=0.05).Conclusion      This method for analysis of the myocardial work provides a more detailed examination of LV structural and functional remodeling and mechanisms for its effects on the LV contractile function in patients with CHF. This method is promising and merits further study in various clinical situations.

Normal Ranges of Global Left Ventricular Myocardial Work Indices in Adults: A Meta-Analysis

BACKGROUND

Recent studies have demonstrated left ventricular myocardial work (MW) is incremental in diagnosis and prognostication when compared to left ventricular ejection fraction and myocardial strain. We performed a meta-analysis of normal ranges of non-invasive MW indices including global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) and to determine confounder that may contribute to variance in reported values.

METHODS

Four databases including Pubmed, Scopus, Embase, and Cochrane Library were searched through January 2021 using the key terms "myocardial work", "global constructive work", "global wasted work", "global work index", "global work efficiency". Studies were included if the articles reported LV myocardial work using 2D transthoracic echocardiography in healthy normal subjects, either in control group or comprising of the entire study cohort. The weighted mean was estimated by using the random effect model with a 95% confidence interval. Heterogeneity across included studies was assessed using the I² test. Funnel plot and Egger's regression test were used to assess potential publication bias RESULTS: The search yielded 476 articles. After abstract and full-text screening, we included 13 datasets with 1665 patients for the meta-analysis. The reported normal mean values of GWI and GCW among the studies were 2010 mmHg% (95% CI, 1907 to 2113), and 2278 mmHg% (95% CI, 2186 to 2369) respectively. The mean GWW was 80 mmHg% (95% CI, 73 to 87), and the mean GWE was 96.0% (95% CI, 96% to 96%). Furthermore, gender significantly contributed to variations in normal values of GWI, GWW, and GWE. No evidence of significant publication bias was observed.

CONCLUSION

In this meta-analysis, we provide echocardiographic reference ranges for non-invasive indices of MW. These normal values could be served as a reference for clinical and research use.