Can myocardial work indices contribute to the exploration of patients with cardiac amyloidosis?

Myocardial Mechanics and Valvular and Vascular Abnormalities in Cardiac Amyloidosis

Cardiac amyloidosis is an infiltrative disease primarily caused by extracellular tissue deposition of amyloid fibrils in the myocardial interstitium. The aim of the present review was to summarize findings regarding changes in myocardial mechanics, valvular abnormalities, and vascular remodeling detected in patients with cardiac amyloidosis.

Myocardial Work for Dynamic Monitoring of Myocardial Injury in Neonatal Asphyxia

To assess the value of parameters of myocardial work for dynamic monitoring of myocardial injury after neonatal asphyxia. Fifty-three neonates with asphyxia admitted within 24 h after delivery were divided into a mild asphyxia group (n = 40) and severe asphyxia group (n = 13). Echocardiography was performed within 24 h post-birth, within 72 h post-birth (48 h after first echo), and during recovery. The left ventricular ejection fraction on M-mode echocardiography and by Simpson's biplane method (LVEF and Bi-EF, respectively), stroke volume (SV), cardiac output (CO), cardiac index (CI), global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), and other parameters were measured. Echocardiographic indicators were compared between groups and over time. GWI was significantly increased at 72 h in the mild asphyxia group (P < 0.05) but showed no significant change over time in the severe asphyxia group (P > 0.05). While GCW increased significantly over time in both groups (P < 0.05), it increased earlier in the mild asphyxia group. Time and grouping factors had independent effects on GWI and GCW (P > 0.05). The characteristics of differences in GWI and GCW between the two groups were different from those for LVEF, Bi-EF, SV, CO, CI, and GLS and their change characteristics with improvement from treatment. GWI and GCW changed significantly during recovery from neonatal asphyxia, and their change characteristics differed between mild and severe asphyxia cases. Myocardial work parameters can be used as valuable supplements to traditional indicators of left ventricular function to dynamically monitor the recovery from myocardial injury after neonatal asphyxia.

Advance of echocardiography in cardiac amyloidosis

Cardiac amyloidosis (CA) occurs when the insoluble fibrils formed by misfolded precursor proteins deposit in cardiac tissues. The early clinical manifestations of CA are not evident, but it is easy to progress to refractory heart failure with an inferior prognosis. Echocardiography is the most commonly adopted non-invasive modality of imaging to visualize cardiac structures and functions, and the preferred modality in the evaluation of patients with cardiac symptoms and suspected CA, which plays a vital role in the diagnosis, prognosis, and long-term management of CA. The present review summarizes the echocardiographic manifestations of CA, new echocardiographic techniques, and the application of multi-parametric echocardiographic models in CA diagnosis.

Prognostic value of left ventricular global constructive work in patients with cardiac amyloidosis

PURPOSE

The aim of the present study was to evaluate the role of ejection fraction (EF), left ventricular (LV) global longitudinal strain (LVGLS) and global constructive work (GCW) as prognostic variables in patients with cardiac amyloidosis (CA).

METHODS

CA patients were retrospectively identified between 2015 and 2021 at a tertiary care hospital. Comprehensive clinical, biochemical, and imaging evaluation including two-dimensional (2D) echocardiography with myocardial work (MW) analysis was performed. A clinical combined endpoint was defined as all-cause mortality and heart failure readmission.

RESULTS

70 patients were followed for 16 (7-37) months and 37 (52.9%) reached the combined endpoint. Patient with versus without clinical events had a significantly lower LVEF (40.71% vs. 48.01%, p = 0.039), LVGLS (-9.26 vs. -11.32, p = 0.034) and GCW (1034.47mmHg% vs. 1424.86mmHg%, p = 0.011). Multivariable analysis showed that LVEF ( odds ratio (OR): 0.904; 95% confidence interval (CI): 0.839-0.973, p = 0.007), LVGLS ( OR: 0.620; 95% CI: 0.415-0.926, p = 0.020) and GCW ( OR: 0.995; 95% CI: 0.990-0.999, p = 0.016) were significant predictors of outcome, but the model including GCW had the best discriminative ability to predict the combined endpoint (C-index = 0.888). A GCW less than 1443mmHg% was able to predict the clinical endpoint with a sensitivity of 94% and a specificity of 64% (Area under the curve (AUC): 0.771 (95% CI: 0.581-0.961; p = 0.005)).

CONCLUSION

In CA patients, GCW may be of additional prognostic value to LVEF and GLS in predicting heart failure hospitalization and all-cause mortality.

Myocardial Work in Echocardiography

Myocardial work is an emerging tool in echocardiography that incorporates left ventricular afterload into global longitudinal strain analysis. Myocardial work correlates with myocardial oxygen consumption, and work efficiency can also be assessed. Myocardial work has been evaluated in a variety of clinical conditions to assess the added value of myocardial work compared to left ventricular ejection fraction and global longitudinal strain. This review showcases the current use of myocardial work in adult echocardiography and its possible role in cardiac pathologies.

Left ventricular myocardial work index and short-term prognosis in patients with light-chain cardiac amyloidosis: a retrospective cohort study

Background

Reports show that the left ventricular myocardial work index (LVMWI) is a novel parameter for evaluating cardiac function. Decompensated heart failure leads to a high rate of early mortality in advanced patients with light-chain cardiac amyloidosis (AL-CA) and prevents them from a relatively delayed response to chemotherapy. This study aimed to assess the association of the LVMWI with short-term outcomes and to construct a simple model for risk stratification.

Methods

A total of 79 patients with an initial diagnosis of AL-CA were included in this retrospective cohort study. LVMWI was calculated by integrating brachial artery cuff blood pressure and left ventricular longitudinal strain (LVLS). The short-term outcome was defined as 6-month all-cause mortality. Receiver operating characteristic (ROC), logistic regression, and Kaplan-Meier analysis were used in this study.

Results

The median follow-up time was 21 months (3-36 months), and 23 (29%) patients died in the first 6 months. The time-dependent ROC and the area under the curve (AUC) showed that the LVMWI had the best predictive potential at the 6-month time point [AUC =0.805; 95% confidence interval (CI): 0.690-0.920]. A bivariate prognostic model based on the LVMWI was constructed, and D-dimer showed a synergistic effect with optimum predicted potential (AUC =0.877; 95% CI: 0.791-0.964). Kaplan-Meier analysis demonstrated that patients with two, one, and none of the variates beyond the cut-off value bore a different risk of 6-month all-cause mortality (accumulated mortality was 86%, 30%, 3%, respectively; log-rank, P<0.001). Multivariate nested logistic regression showed that the level of D-dimer provided an incremental prognostic value (Δχ²=10.3; P=0.001) to the value determined from New York Heart Association (NYHA) classification and the LVMWI.

Conclusions

The LVMWI is associated with the short-term outcome of patients with AL-CA. The D-dimer test provides additional prognostic information for the LVMWI.

Cardiopulmonary Exercise Physiology in AL Amyloidosis Patients with Cardiac Involvement and Its Association with Cardiac Imaging Parameters

Background: Cardiopulmonary exercise testing (CPET) has been widely used for the functional evaluation of patients with heart failure. Patients with amyloidosis and cardiac involvement typically present with heart failure with preserved or mildly reduced ejection fraction. We sought to evaluate the use of CPET parameters in patients with AL amyloidosis for the assessment of disease severity and prognosis and their association with cardiac imaging findings. Methods: A single-center prospective analysis was conducted, which included 23 consecutive ambulatory patients with AL amyloidosis with cardiac involvement, not requiring hospitalization or intravenous diuretics. Patient evaluation included CPET, laboratory testing, echocardiography and cardiac MRI. The cohort was divided according to the presence of high-risk CPET characteristics (below median peak VO2 and above median VE/VCO2). Results: Patients with AL amyloidosis and cardiac involvement (median age was 60 years (56.5% males) had median peak relative VO2 (VO2/kg) of 17.8 mL/kg/min, VE/VCO2 slope of 39.4 and circulatory power of 2362.5 mmHg⋅mL/kg/min. Peak relative VO2 gradually declined across Mayo stages (p = 0.046) and exhibited a significant inverse correlation with NT-proBNP levels (r = −0.52, p = 0.01). Among imaging parameters, peak VO2 positively correlated with global work efficiency (r = 0.61, p < 0.001), and global work index (r = 0.45, p = 0.04). The group of patients with high-risk CPET findings showed evidence of more advanced disease, such as higher NT-proBNP levels (p = 0.007), increased septal and posterior left ventricular wall thickness (p = 0.043 and p = 0.033 respectively) and decreased global work efficiency (p = 0.027) without substantial differences in cardiac MRI parameters. In this group of patients, peak VO2 and VE/VCO2 were not associated significantly with overall survival and cardiac response at one year. Conclusion: In patients with AL amyloidosis, evaluation of exercise capacity with CPET identified a group of patients with more advanced cardiac involvement. The potential of CPET as a risk stratification tool in AL amyloidosis with cardiac involvement warrants further research.

New Advanced Imaging Parameters and Biomarkers-A Step Forward in the Diagnosis and Prognosis of TTR Cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative disorder characterized by extracellular myocardial deposits of amyloid fibrils, with poor outcome, leading to heart failure and death, with significant treatment expenditure. In the era of a novel therapeutic arsenal of disease-modifying agents that target a myriad of pathophysiological mechanisms, timely and accurate diagnosis of ATTR-CM is crucial. Recent advances in therapeutic strategies shown to be most beneficial in the early stages of the disease have determined a paradigm shift in the screening, diagnostic algorithm, and risk classification of patients with ATTR-CM. The aim of this review is to explore the utility of novel specific non-invasive imaging parameters and biomarkers from screening to diagnosis, prognosis, risk stratification, and monitoring of the response to therapy. We will summarize the knowledge of the most recent advances in diagnostic, prognostic, and treatment tailoring parameters for early recognition, prediction of outcome, and better selection of therapeutic candidates in ATTR-CM. Moreover, we will provide input from different potential pathways involved in the pathophysiology of ATTR-CM, on top of the amyloid deposition, such as inflammation, endothelial dysfunction, reduced nitric oxide bioavailability, oxidative stress, and myocardial fibrosis, and their diagnostic, prognostic, and therapeutic implications.

Multimodality Imaging in Cardiomyopathies with Hypertrophic Phenotypes

Multimodality imaging is a comprehensive strategy to investigate left ventricular hypertrophy (LVH), providing morphologic, functional, and often clinical information to clinicians. Hypertrophic cardiomyopathy (HCM) is defined by an increased LV wall thickness not only explainable by abnormal loading conditions. In the context of HCM, multimodality imaging, by different imaging techniques, such as echocardiography, cardiac magnetic resonance, cardiac computer tomography, and cardiac nuclear imaging, provides essential information for diagnosis, sudden cardiac death stratification, and management. Furthermore, it is essential to uncover the specific cause of HCM, such as Fabry disease and cardiac amyloidosis, which can benefit of specific treatments. This review aims to elucidate the current role of multimodality imaging in adult patients with HCM.

Global Left Ventricular Myocardial Work Efficiency in Heart Failure Patients with Cardiac Amyloidosis: Pathophysiological Implications and Role in Differential Diagnosis

Introduction

Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy and a common cause of heart failure with preserved and mid-range ejection fraction (HFpEF and HFmrEF). Left ventricular (LV) systolic assessment is pivotal in differential diagnostic and prognostic stratification in CA. However, nondeformation and deformation-based parameters classically implied had many limitations. Myocardial work (MW) has been recently introduced for the evaluation of myocardial performance, in a load-independent fashion, in patients with cardiomyopathies.

Aims

This study aimed to evaluate MW parameters in LV performance assessment in CA and their possible role in differential diagnosis between AL and ATTR forms, compared with other echocardiographic parameters, also exploring the possible association between MW parameters and blood biomarkers.

Materials and Methods

The study population consisted of 25 patients with CA (10 with AL amyloidosis and 15 with wild-type ATTR [ATTRwt] form) and HFpEF or HFmrHF, enrolled between March 2018 and December 2019, undergoing a comprehensive clinical, biochemical, and imaging evaluation. Ten healthy individuals were studied as controls. ATTR patients had a noninvasive diagnosis of wtATTR-CA (positive ^99mTc-hydroxy methylene-diphosphonate scintigraphy with a negative hematological screening), while AL patients underwent endomyocardial biopsy. All patients underwent standard transthoracic echocardiography. MW and related indices were estimated using a vendor-specific module.

Results

Compared to the ATTRwt group, patients in the AL group showed a more pronounced myocardial performance impairment assessed by Global Word Efficiency (GWE: 83.5% ± 6.3% vs. 88.2% ± 3.6%; P = 0.026). In multiple linear regression analysis, cardiac troponin I (Β = -0.55; P < 0.0001), global longitudinal strain (Β =0.35; P < 0.008), and regional relative strain ratio (Β = -0.30; P < 0.016) were significant predictors of GWE reduction in CA patients. At receiver operating characteristics curve analysis, among all other deformation-based and nondeformation-based echocardiographic parameters, GWE showed the highest area under the curve (AUC) (AUC 0.74; 95% CI: 0.55-0.96; P < 0.04). The optimal cutoff was determined by sensitivity/specificity analysis: a GWE < 86.5% identified patients with AL amyloidosis with a sensitivity and specificity, respectively, of 80.0% and 66.7%.

Conclusions

The results of our pivotal study seem to highlight the importance of new deformation parameters to study myocardial performance in patients with CA, and to differentiate between AL CA and ATTR CA.

The Role of New Imaging Technologies in the Diagnosis of Cardiac Amyloidosis

Cardiac amyloidosis is an infiltrative disorder caused by transthyretin or immunoglobulin free light-chain deposition, which determines clinical disease with similar phenotype but different time course, prognosis and therapy. Multimodality imaging is the cornerstone for disease diagnosis and management. Multimodality imaging has revolutionized the approach to the disease favoring its awareness and simplifying its diagnosis, especially in ATTR cardiac amyloidosis. This describes the different imaging tools, from the traditional to the more novel ones, and highlights the different approach in each different setting (prognosis, subtyping, prognosis, monitoring disease progression, and response to therapy).

Myocardial Work Does Not Have Additional Diagnostic Value in the Assessment of ATTR Cardiac Amyloidosis

Background: Reduced LV longitudinal strain (GLS) and increased relative apical sparing (RELAPS) and increased wall thickness have been proposed as features for transthyretin cardiac amyloidosis (ATTR-CA). Myocardial work (MW) has recently been shown as useful afterload independent disease marker, hence we aimed to investigate its use in differentiating ATTR-CA from heart failure with increased septal thickness but no cardiac amyloidosis (CA) (HFnCA). Methods: This study included patients with HF and increased septal thickness ≥ 14 mm. We included 59 patients with hereditary (ATTRv) and 27 wild type transthyretin amyloidosis (ATTRwt) described as ATTR-CA based on DPD scintigraphy. We also enrolled 30 non-amyloidosis heart failure patients with negative DPD scintigraphy, as a control group. Myocardial work (MW) was used to assess the index (GWI), constructive (GCW) and wasted (GWW) work. Relative wall thickness (RWT) and relative apical sparing (RELAPS) were tested as conventional measures. Results: The RWT and RELAPS were higher in ATTR-CA (p < 0.001) and predicted ATTR-CA (RWT; AUC = 0.84, p < 0.001) and RELAPS (AUC = 0.81, p < 0.001). MW; GWI (p = 0.04), GCW (p = 0.03), GWW (p = 0.001) were all lower in ATTR-CA compared with HFnCA but only GWW predicted ATTR-CA, (AUC = 0.75, p < 0.001). Binary logistic univariate regression analysis showed RWT (p = 0.003, β = 16.2) and RELAPS (p = 0.003, β = 2.3) to be associated with ATTR-CA but not MW. GWI and GCW correlated with NT-proBNP (p < 0.05) and Troponin (p < 0.01), but not RWT or RELAPS. Conclusion: Myocardial work had lower accuracy, compared to RWT or RELAPS, in identifying ATTR-CA but was better related to biomarkers. Thus, MW assessment is unlikely to have additional value in improving the diagnosis of heart failure due to ATTR-CA.

Myocardial Work by Echocardiography: Principles and Applications in Clinical Practice

Left ventricular (LV) global longitudinal strain (GLS) has established itself in the last decade as a reliable, more objective method for the evaluation of LV systolic function, able to detect subtle abnormalities in LV contraction even in the presence of preserved ejection fraction (EF). However, recent studies have demonstrated that GLS, similar to LV EF, has important load dependency. Non-invasive myocardial work (MW) quantification has emerged in the last years as an alternative tool for myocardial function assessment. This new method, incorporating measurement of strain and LV pressure, has shown to overcome GLS and LV EF limitations and provide a loading-independent evaluation of myocardial performance. The presence of a commercially available echocardiographic software for the non-invasive MW calculation has allowed the application of this new method in different settings. This review sought to provide an overview on the current knowledge of non-invasive MW estimation, showing its potential applications and possible added value in clinical practice.

Afterload-related reference values for myocardial work indices

BACKGROUND

The novel noninvasive pressure-strain loop (PSL) is a reliable tool that reflects myocardial work (MW). Systolic blood pressure (SBP) is the only independent factor for MW indices. However, afterload-related reference values have not been previously reported. The aim of the present study was to establish reference values for MW parameters by wide range SBP grading.

METHODS

We prospectively selected healthy individuals and subjects with SBP ≥ 140 mmHg at the time of study without myocardial remodeling. MW parameters were collected and the reference values achieved were grouped by SBP in 10-mmHg.

RESULTS

Significant differences were noted among the SBP-groups for global work index (GWI) and global constructive work (GCW). The majority of statistical comparisons of the differences in GWI and GCW were significant at each SBP-group. With SBP ranging from 90 to 189 mmHg, the parameters GWI and GCW tended to increase linearly with afterload. Overall, the global wasted work (GWW) tended to rise as SBP was increased, but not all of the differences noted in GWW were significant for each SBP-group. Global work efficiency (GWE) remained stable across all SBP-groups, with the exception of a slight drop noted when it exceeded 160 mmHg.

CONCLUSIONS

The amount of MW but not the work efficiency varied greatly according to the different afterload. This finding cannot be ignored during clinical research or diagnosis and afterload-related reference values are required to make a reasonable judgment on the myocardial function.

Myocardial Work Assessment for the Prediction of Prognosis in Advanced Heart Failure

Objectives: The aim of this study was to investigate whether echocardiographic assessment of myocardial work is a predictor of outcome in advanced heart failure.

Background: Global work index (GWI) and global constructive work (GCW) are calculated by means of speckle tracking, blood pressure measurement, and a normalized reference curve. Their prognostic value in advanced heart failure is unknown.

Methods: Cardiopulmonary exercise testing and echocardiography with assessment of GWI and GCW was performed in patients with advanced heart failure caused by ischemic heart disease or dilated cardiomyopathy (n = 105). They were then followed up repeatedly. The combined endpoint was all-cause death, implantation of a left ventricular assist device, or heart transplantation.

Results: The median patient age was 54 years (interquartile range [IQR]: 48–59.9). The mean left ventricular ejection fraction was 27.8 ± 8.2%, the median NT-proBNP was 1,210 pg/ml (IQR: 435–3,696). The mean GWI was 603 ± 329 mmHg% and the mean GCW was 742 ± 363 mmHg%. The correlation between peak oxygen uptake and GWI as well as GCW was strongest in patients with ischemic cardiomyopathy (r = 0.56, p = 0.001 and r = 0.53, p = 0.001, respectively). The median follow-up was 16 months (IQR: 12–18.5). Thirty one patients met the combined endpoint: Four patients died, eight underwent transplantation, and 19 underwent implantation of a left ventricular assist device. In the multivariate Cox regression analysis, only NYHA class, NT-proBNP and GWI (hazard ratio [HR] for every 50 mmHg%: 0.85; 95% CI: 0.77–0.94; p = 0.002) as well as GCW (HR for every 50 mmHg%: 0.86; 95% CI: 0.79–0.94; p = 0.001) were identified as independent predictors of the endpoint. The cut-off value for predicting the outcome was 455 mmHg% for GWI (AUC: 0.80; p < 0.0001; sensitivity 77.4%; specificity 71.6%) and 530 mmHg% for GCW (AUC: 0.80; p < 0.0001; sensitivity 74.2%; specificity 78.4%).

Conclusions: GWI and GCW are powerful predictors of outcome in patients with advanced heart failure.