Global Left Ventricular Myocardial Work Efficiency in Healthy Individuals and Patients with Cardiovascular Disease

Global Left Ventricular Myocardial Work Efficiency and Long-Term Prognosis in Patients After ST-Segment-Elevation Myocardial Infarction

BACKGROUND

Left ventricular (LV) global longitudinal strain has demonstrated incremental prognostic value over LV ejection fraction in patients with ST-segment-elevation myocardial infarction. However, LV global longitudinal strain does not take into consideration the effect of afterload. Novel speckle-tracking echocardiographic indices of myocardial work integrate blood pressure measurements (afterload) with LV global longitudinal strain. The present study aimed to investigate the prognostic value of global LV myocardial work efficiency (GLVMWE; reflecting LV performance) obtained from pressure-strain loops with echocardiography in patients with ST-segment-elevation myocardial infarction.

METHODS

A total of 507 ST-segment-elevation myocardial infarction patients (mean age, 61±11 years; 76% men) were retrospectively analyzed. LV ejection fraction and GLVMWE were measured by transthoracic echocardiography within 48 hours of admission. GLVMWE was defined as the ratio of constructive work divided by the sum of constructive and wasted work in all LV segments and expressed as a percentage. Spline curve analysis was used to define the association between reduced GLVMWE and all-cause death.

RESULTS

After a median follow-up of 80 months (interquartile range, 67-97 months), 40 (8%) patients died. Patients with reduced GLVMWE (<86%) showed higher cumulative rates of all-cause mortality (17.5% versus 4.7%; log-rank P<0.001) in comparison with patients with preserved GLVMWE (≥86%). Reduced GLVMWE (<86%) showed an independent association with all-cause mortality (hazard ratio, 3.167 [95% CI, 1.679-5.972]; P<0.001).

CONCLUSIONS

Reduced GLVMWE (<86%) measured by transthoracic echocardiography within 48 hours of admission in ST-segment-elevation myocardial infarction patients is associated with worse long-term survival.

Impact of cardiovascular risk factors on myocardial work-insights from the STAAB cohort study

Myocardial work is a new echocardiography-based diagnostic tool, which allows to quantify left ventricular performance based on pressure–strain loops, and has been validated against invasively derived pressure–volume measurements. Myocardial work is described by its components (global constructive work [GCW], global wasted work [GWW]) and indices (global work index [GWI], global work efficiency [GWE]). Applying this innovative concept, we characterized the prevalence and severity of subclinical left ventricular compromise in the general population and estimated its association with cardiovascular (CV) risk factors. Within the Characteristics and Course of Heart Failure STAges A/B and Determinants of Progression (STAAB) cohort study we comprehensively phenotyped a representative sample of the population of Würzburg, Germany, aged 30–79 years. Indices of myocardial work were determined in 1929 individuals (49.3% female, mean age 54 ± 12 years). In multivariable analysis, hypertension was associated with a mild increase in GCW, but a profound increase in GWW, resulting in higher GWI and lower GWE. All other CV risk factors were associated with lower GCW and GWI, but not with GWW. The association of hypertension and obesity with GWI was stronger in women. We conclude that traditional CV risk factors impact selectively and gender-specifically on left ventricular myocardial performance, independent of systolic blood pressure. Quantifying active systolic and diastolic compromise by derivation of myocardial work advances our understanding of pathophysiological processes in health and cardiac disease.

Value of quantitative analysis of left ventricular systolic function in patients on maintenance hemodialysis based on myocardial work technique

Background

This study aimed to determine the left ventricular (LV) systolic function in patients on maintenance hemodialysis (MHD) using the myocardial work (MW) technique and investigate the clinical value of the MW technique for the quantitative analysis of left ventricular (LV) systolic function in MHD patients with left ventricular hypertrophy (LVH).

Methods

A total of 68 MHD patients and 35 controls were registered in this study. The MHD patients were divided into the non-left ventricular hypertrophy (NLVH) group (n = 35) and the LVH group (n = 33) according to the LV mass index (LVMI). MW was used to generate the LV global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), and global wasted work (GWW), global work efficiency (GWE). GLS and the MW parameters (GWI, GCW, GWW, GWE) were compared between groups and the correlations between these parameters and the LV ejection fraction (LVEF) in the LVH group were examined. The receiver operating characteristic (ROC) curve was used to evaluate the efficacy of MW parameters and GLS for the assessment of LV systolic dysfunction in MHD with LVH patients.

Results

The LVH group had significantly lower GWE, GWI, GCW, and GLS but higher GWW than the control and NLVH groups. Compared with the control group, the NLVH group had significantly lower GWE and GLS and higher GWW, but no significant differences in GWI, GCW were observed between these two groups. The LVEF was negatively correlated with GWW in MHD patients, but positively correlated with GWI, GWE, and GCW in the LVH group. Receiver operating characteristic curve (ROC) analysis revealed that GWE, GWW, GWI, and GCW had appreciable area under the curve (AUC), sensitivity, and specificity for evaluating LV function in LVH patients on MHD.

Conclusions

The MW parameters can quantitatively represent the LV myocardial work in MHD patients. Thus, the technique provides a new method for the quantitative evaluation of LV systolic function in MHD with LVH patients.

Quantitative assessment of left ventricular myocardial work in chronic kidney disease patients by a novel non-invasive pressure-strain loop analysis method

This study aimed to quantitatively evaluate myocardial work (MW) in advanced stage 3-5 chronic kidney disease (CKD) by a novel non-invasive left ventricular (LV) Pressure-strain loop analysis (PSL). 144 patients with CKD were included (68 with stage 3 CKD group, 76 with stage 4/5 CKD group), and 48 healthy patients were recruited as the control group. All subjects had undergone transthoracic echocardiography. LV myocardial work and efficiency were estimated from LV PSL analysis. There was a significant progressive increase in global work waste (GWW) and reduction in global work efficiency (GWE) in CKD compared to normal controls. No difference in global work index (GWI) and global constructive work (GCW) was observed among the three groups. Subdivided analysis according to systolic blood pressure (SBP) and LV geometry discovered that increased GWW seems to be present frequently in CKD patients with elevated SBP or LV hypertrophy (LVH). Multivariate analysis showed increased peak strain dispersion (PSD), SBP, LV mass index (LVMI), and decreased estimated glomerular filtration rate (eGFR) were significantly associated with increased GWW. The decline of renal function followed by impaired paralleled myocardial energy exploitation. Moreover, increased PSD, SBP, LVMI, and decreased eGFR might be potential drivers of increased GWW.

A Prospective Comparative Study on Cardiac Alterations After Surgery and Drug Treatment of Primary Aldosteronism

BACKGROUND

Current guideline recommends both surgery and drug treatment for primary aldosteronism. Treatment effects on the cardiac structure and function remain under investigation.

OBJECTIVE

We performed a prospective study in patients with primary aldosteronism to compare effects of surgery and drug treatment on the cardiac structure and function as assessed by the left ventricular (LV) pressure-strain loop, a novel echocardiographic technique that incorporates myocardial deformation and LV pressure.

METHODS

Our study included 39 and 28 patients treated with surgery and a mineralocorticoid antagonist, respectively. We performed conventional and speckle tracking echocardiography at baseline and 3 and 6 months of follow-up.

RESULTS

During follow-up, both surgery and drug treatment normalized serum potassium concentration and significantly reduced blood pressure. Both treatments significantly and similarly decreased LV mass index and left atrial volume index. However, only in the surgery group did global wasted work significantly decrease (200.8 ± 86.7 at baseline vs. 142.1 ± 58.1 mmHg% at 6 months) and global work efficiency (91.5 ± 3.1 vs. 93.6 ± 2.3%) and global longitudinal strain (-18.3 ± 2.7 vs. -19.2 ± 1.9%) significantly (p < 0.01) increase at 6 months of follow-up. The corresponding differences from the changes in the drug treatment group were 39.5 mmHg% (95% CI, 17.1, 62.0 mmHg%), -1.64% (95% CI, -2.56, -0.71%), and -0.85% (95% CI, -1.51, -0.20%), respectively. In addition, the changes in global wasted work at 6 months of follow-up was significantly correlated with that in 24-h urinary aldosterone excretion in the drug treatment group (r = 0.54) and two groups combined (r = 0.55), but not the surgery group.

CONCLUSION

In spite of similar serum potassium normalization and blood pressure control, surgical removal of an adrenal gland, but not mineralocorticoid receptor antagonism, showed early improvement in cardiac function.

Assessment of Left Ventricular Global Myocardial Work in Patients With Different Degrees of Coronary Artery Stenosis by Pressure-Strain Loops Analysis

Global myocardial work (MW) analysis by pressure-strain loops (PSL) allows the non-invasive assessment of left ventricular (LV) function. We aimed to investigate the relationship between LV global MW and the degree of coronary artery stenosis in suspected coronary artery disease (CAD) patients with normal LV ejection fraction and regional wall motion. A total of 164 suspected CAD patients were divided into four groups according to coronary artery angiography. The results showed that global work efficiency (GWE) as the most significant predictor in all MW parameters had the optimal cut-off value of 94.5% for detecting moderate stenosis, and the sensitivity and specificity was 89.7% and 85.8%, respectively. A cut-off value of 94.0% for GWE was the most significant predictor of severe stenosis, and the sensitivity and specificity was 81.4% and 76.1%, respectively. In conclusion, LV global MW is a sensitive tool in detecting the degree of coronary artery stenosis and a potential valuable method to provide early diagnosis for CAD patients.

Value of territorial work efficiency estimation in non-ST-segment-elevation acute coronary syndrome: a study with non-invasive left ventricular pressure-strain loops

Non-ST-segment-elevation acute coronary syndrome (NSTE-ACS) patients with normal left ventricular (LV) ejection fraction (LVEF) and wall motion require a non-invasive tool to detect LV risk areas. This study utilized non-invasive LV pressure-strain loops to evaluate territorial myocardial work efficiency (WE) for identifying obstructive coronary artery stenosis, in patients with non-obstructive or obstructive coronary artery stenosis NSTE-ACS, the latter with or without occlusion. Global and territorial longitudinal strain (LS) analyses were performed via speckle-tracking imaging before coronary angiography. LV pressure-strain loops estimated global and territorial myocardial work index (MWI), constructive work (CW), wasted work (WW), and WE. Receiver operating characteristic curve analysis was used to determine the optimal cutoff value of independent parameters to detect obstructive coronary artery stenosis. Compared with non-obstructive, obstructive coronary artery stenosis showed significantly lower global and territorial LS, MWI, CW, and WE, and higher WW. Territorial LS, MWI, CW, and WE were significantly worse in territories of coronary occlusion. Territorial WE was the best parameter for predicting obstructive coronary artery stenosis (AUC 0.80, cutoff < 96%, sensitivity 73%, specificity 70%, P < 0.001). In patients with NSTE-ACS with normal wall motion and LVEF, territorial WE is more accurate than territorial LS or MWI to identify LV risk areas.

Evaluation of Left Ventricular Myocardial Work Performance in Patients Undergoing On-Pump and Off-Pump Coronary Artery Bypass Surgery

Purpose: Benefits of off-pump coronary bypass (OPCAB) over on-pump (ONCAB) remain controversial. We aimed to evaluate the early impacts of OPCAB vs ONCAB for varying left ventricular (LV) function baselines by applying the non-invasive myocardial work (MW) analysis, which enables further insights in cardiac mechanics, contractility, and efficacy.

Methods: We retrospectively analyzed 98 patients (55 ONCAB vs 43 OPCAB). Transthoracic echocardiography (TTE) and concurrent arterial blood pressure measurements taken at rest, prior to, and early after surgery were performed. Global myocardial work index (GMWI), global constructive work (GCW), and global work efficiency (GWE), inter alia, were quantified.

Results: Preoperatively, OPCAB patients had significantly lower values than ONCAB patients in terms of GMWI (1404.33 ± 585.41 mmHg% vs 1619.07 ± 535.42 mmHg%, p = 0.039), GWE (90% (60%, 96%) vs 93% (74%, 98%), p = 0.028). After surgery, GMWI was reduced in both groups. However, a more significant GMWI impairment occurred early after ONCAB than after OPCAB (−343.14 ± 35.20 mmHg%, p <0.001 vs −224.04 ± 120.91 mmHg%, p = 0.042).

Conclusion: Despite lower preoperative LV function in OPCAB patients, GMWIs after OPCAB were superior to ONCAB, indicating better preservation of systolic LV function early after OPCAB by means of contractility compared to ONCAB. Further studies should investigate the long-term course of MW response and their clinical impact.

Myocardial Work in Nonobstructive Hypertrophic Cardiomyopathy: Implications for Outcome

BACKGROUND

Noninvasive left ventricular (LV) pressure-strain loop analysis is emerging as a new echocardiographic method to evaluate LV function, integrating longitudinal strain by speckle-tracking analysis and sphygmomanometrically measured blood pressure to estimate myocardial work. The aims of this study were (1) to describe global and segmental myocardial work in patients with hypertrophic cardiomyopathy (HCM), (2) to assess the correlation between myocardial work and other echocardiographic parameters, and (3) to evaluate the association of myocardial work with adverse outcomes.

METHODS

One hundred ten patients with nonobstructive HCM (mean age, 55 ± 15 years; 66% men), with different phenotypes (apical, concentric, and septal hypertrophy), and 35 age- and sex-matched healthy control subjects were included. The following myocardial work indices were included: myocardial work index, constructive work (CW), wasted work, and cardiac efficiency. The combined end point included all-cause mortality, heart transplantation, heart failure hospitalization, aborted sudden cardiac death, and appropriate implantable cardioverter-defibrillator therapy.

RESULTS

Mean global CW (1,722 ± 602 vs 2,274 ± 574 mm Hg%, P < .001), global cardiac efficiency (93% [89%-95%] vs 96% [96%-97%], P < .001), and global MWI (1,534 ± 551 vs 1,929 ± 473 mm Hg%) were significantly reduced, while global wasted work (104 mm Hg% [66-137 mm Hg%] vs 71 mm Hg% [49-92 mm Hg%], P < .001) was increased in patients with HCM compared with control subjects. Segmental impairment in CW colocalized with maximal wall thickness (HCM phenotype), and global CW correlated with LV wall thickness (r = -0.41, P < .001), diastolic function (r = -0.27, P = .001), and QRS duration (r = -0.28, P = .001). Patients with global CW > 1,730 mm Hg% (the median value) experienced better event-free survival than those with global CW < 1,730 mm Hg% (P < .001).

CONCLUSIONS

Myocardial work, assessed noninvasively using echocardiography and blood pressure measurement, is reduced in patients with nonobstructive HCM; it correlates with maximum LV wall thickness and is significantly associated with a worse long-term outcome.

Noninvasive Myocardial Work Index: Characterizing the Normal and Ischemic Response to Exercise

BACKGROUND

Myocardial work index (MWI) and work efficiency are new parameters for assessing left ventricular function. We aim to characterize the normal response to exercise in a mixed population and determine whether MWI can identify patients with inducible ischemia.

METHODS

Patients were retrospectively enrolled from an existing database of exercise stress echocardiography. Inclusion criteria were a clinical indication of possible ischemia and technical suitability to calculate MWI. Exclusion criteria were abnormal baseline left ventricular function or inadequate image quality. Echocardiograms positive for ischemia were defined by independent visual assessment and compared with angiographic findings where available. Myocardial work index was determined using a proprietary algorithm and efficiency calculated as constructive work divided by the sum of constructive and wasted work.

RESULTS

A total of 177 patients met inclusion criteria; 117 were excluded, leaving 40 normal and 20 positive tests. During normal exercise, global MWI increased 54% (from 2,296 to 3,523 mm Hg%) and efficiency remained at 96%. However, in patients with inducible ischemia, MWI decreased in affected segments, global MWI did not increase (2,069-2,070 mm Hg%), and global efficiency fell from 93% to 87%. The receiver operating characteristic curve for MWI had an area under the curve of 0.94.

CONCLUSIONS

During normal exercise, MWI increases and efficiency remains unchanged. However, during exercise-induced ischemia, MWI paradoxically decreases in affected segments, while globally MWI fails to increase and efficiency decreases. We have demonstrated that MWI can be applied to stress echocardiography to identify ischemia, but its utility remains uncertain. Further research that makes comparisons with an objective measure of functional ischemia is needed.

Noninvasive Myocardial Work Indices 3 Months after ST-Segment Elevation Myocardial Infarction: Prevalence and Characteristics of Patients with Postinfarction Cardiac Remodeling

BACKGROUND

Assessment of left ventricular (LV) remodeling after ST-segment elevation myocardial infarction (STEMI) is pivotal for patient management. Noninvasive myocardial work indices obtained from echocardiography-derived strain-pressure loops provide a new tool that permits characterization of LV mechanics. We aimed at characterizing myocardial work indices in patients with LV remodeling after STEMI versus patients without remodeling.

METHODS

Six-hundred STEMI patients were retrospectively analyzed (456 men, mean age: 61 ± 11 years) and divided according to the presence of LV remodeling 3 months after the index admission (≥20% increase in LV end-diastolic volume). Noninvasive myocardial work indices were measured at 3 months after STEMI.

RESULTS

LV remodeling was observed in 150 patients (25%) who showed more impaired global myocardial work indices compared with their counterparts: work index (1,708 ± 522 mm Hg% vs 1,979 ± 450 mm Hg%; P < .001), constructive work (1,941 ± 598 mm Hg% vs 2,272 ± 519 mm Hg%; P < .001), and work efficiency (92% [range 88%-96%] vs 95% [range 93%-96%]; P < .001). In addition, patients with LV remodeling had significantly increased wasted work (116 mm Hg% [range 73-184 mm Hg%] vs 91 mm Hg% [range 61-132 mm Hg%]; P < .001). The frequency of impaired global work index, constructive and work efficiency, and increased wasted work was significantly higher among patients with LV remodeling compared with their counterparts: 21.3%, 34.7%, 34.7%, and 14.0%, respectively, versus 5.3%, 9.6%, 8.9%, and 4.9%, respectively (P < .001).

CONCLUSIONS

At 3-month follow-up after STEMI, patients with LV remodeling revealed more impaired myocardial work indices compared with patients without LV remodeling. The prevalence of impaired myocardial work indices was higher among patients with LV remodeling compared with patients without.

Value of myocardial work for assessment of myocardial adaptation to increased afterload in patients with high blood pressure at peak exercise

Non-invasive myocardial work (MW) indices are superior to global longitudinal strain (GLS) to assess left ventricular (LV) mechanics in situations where afterload is abnormally high. The rotational motion of the apex provides an accurate index of LV contractility. To date, there are no data about MW values during stress echocardiography (SE), particularly for the apex. Our study aims at assessing MW indices at peak exercise to better understand LV mechanics in patients with high peak systolic blood pressure (SBP). A total of 81 patients without structural or ischemic heart disease referred for SE between January and June 2019 were included. BP measurements, GLS and MW indices were performed at rest and peak exercise. In order to quantify the role of the apex, apical work fraction (AWF) was also calculated and further stratified by peak SBP. A peak SBP > 180 mmHg was considered abnormally high. There were 36 (44%) patients who had peak SBP > 180 mmHg. They showed similar resting GLS and MW values when compared to control. However, peak stress global work index, constructive work and wasted work (GWW) increased significantly (P-value < 0.05), with a relatively constant global work efficiency. In the multivariate analysis, peak SBP > 180 mmHg was associated with threefold increased odds of abnormal peak GWW > 96.5 mmHg% (median value) (odds ratio 3.0, P-value 0.003). Apical work increased significantly when stratified by peak SBP (P-value 0.003) and AWF increased from 33 ± 3% to 37 ± 3% (rest-stress), P-value < 0.0001, but remained constant when stratified by peak SBP. Our analysis provides new data on MW indices at peak stress, particularly for patients with abnormal peak SBP response, and supports the role and the contribution of the apex to MW.

[Myocardial work in assessment of left ventricular systolic function]

This review focuses on a new method for noninvasive, complex evaluation of left ventricular (LV) systolic function using an echocardiography-based technology of computing indexes of myocardial performance by construction of pressure-deformation curves. Since this new method accounts for the effect of afterload on myocardial contractility, the article presents data demonstrating advantages of the evaluation of LV myocardial performance over the speckle-tracking echocardiography and other methods in diagnostics of several diseases. The review provides a description of this method and its advantages and limitations. The authors analyzed results of major studies on evaluation of LV performance. Prospects of implementation and practical use of the method are discussed in the aspects of diagnostics of cardiovascular diseases and risk stratification for different groups of patients.