Myocardial Efficiency: A Fundamental Physiological Concept on the Verge of Clinical Impact

Left Ventricular Unloading in Extracorporeal Membrane Oxygenation: A Clinical Perspective Derived from Basic Cardiovascular Physiology

PURPOSE OF REVIEW

To present an abridged overview of the literature and pathophysiological background of adjunct interventional left ventricular unloading strategies during veno-arterial extracorporeal membrane oxygenation (V-A ECMO). From a clinical perspective, the mechanistic complexity of such combined mechanical circulatory support often requires in-depth physiological reasoning at the bedside, which remains a cornerstone of daily practice for optimal patient-specific V-A ECMO care.

RECENT FINDINGS

Recent conventional clinical trials have not convincingly shown the superiority of V-A ECMO in acute myocardial infarction complicated by cardiogenic shock as compared with medical therapy alone. Though, it has repeatedly been reported that the addition of interventional left ventricular unloading to V-A ECMO may improve clinical outcome. Novel approaches such as registry-based adaptive platform trials and computational physiological modeling are now introduced to inform clinicians by aiming to better account for patient-specific variation and complexity inherent to V-A ECMO and have raised a widespread interest. To provide modern high-quality V-A ECMO care, it remains essential to understand the patient's pathophysiology and the intricate interaction of an individual patient with extracorporeal circulatory support devices. Innovative clinical trial design and computational modeling approaches carry great potential towards advanced clinical decision support in ECMO and related critical care.

GLP-1 receptor agonists and myocardial metabolism in atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Many medical conditions, including hypertension, diabetes, obesity, sleep apnea, and heart failure (HF), increase the risk for AF. Cardiomyocytes have unique metabolic characteristics to maintain adenosine triphosphate production. Significant changes occur in myocardial metabolism in AF. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been used to control blood glucose fluctuations and weight in the treatment of type 2 diabetes mellitus (T2DM) and obesity. GLP-1RAs have also been shown to reduce oxidative stress, inflammation, autonomic nervous system modulation, and mitochondrial function. This article reviews the changes in metabolic characteristics in cardiomyocytes in AF. Although the clinical trial outcomes are unsatisfactory, the findings demonstrate that GLP-1 RAs can improve myocardial metabolism in the presence of various risk factors, lowering the incidence of AF.

Molecular Imaging of Heart Failure: An Update and Future Trends

Molecular imaging can detect and quantify pathophysiological processes underlying heart failure, complementing evaluation of cardiac structure and function with other imaging modalities. Targeted tracers have enabled assessment of various cellular and subcellular mechanisms of heart failure aiming for improved phenotyping, risk stratification, and personalized therapy. This review outlines the current status of molecular imaging in heart failure, accompanied with discussion on novel developments. The focus is on radionuclide methods with data from clinical studies. Imaging of myocardial metabolism can identify left ventricle dysfunction caused by myocardial ischemia that may be reversible after revascularization in the presence of viable myocardium. In vivo imaging of active inflammation and amyloid deposition have an established role in the detection of cardiac sarcoidosis and transthyretin amyloidosis. Innervation imaging has well documented prognostic value in predicting heart failure progression and arrhythmias. Tracers specific for inflammation, angiogenesis and myocardial fibrotic activity are in earlier stages of development, but have demonstrated potential value in early characterization of the response to myocardial injury and prediction of cardiac function over time. Early detection of disease activity is a key for transition from medical treatment of clinically overt heart failure towards a personalized approach aimed at supporting repair and preventing progressive cardiac dysfunction.

[Morphofunctional Analysis of the Role of Epicardial Adipose Tissue in the Formation of the Obesity Paradox in Chronic Heart Failure]

Based on the available modern medical literature, the article summarizes data on the morpho-functional significance of epicardial adipose tissue (EAT) in health and heart failure, analyzes the likelihood and reliability of the formation of the obesity paradox, and also discusses its possible morpho-functional mechanisms. The authors reviewed and analyzed the consequences of the obesity paradox in the aspect of the normal EAT phenotype protectivity. The review proposed ways of further research in this direction aimed at a deep anatomical and physiological analysis and at determining the morpho-functional role of EAT in the adaptive mechanisms of myocardial trophic provision, which may be an important part of the pathogenetic connection between obesity and CHF and, therefore, can improve outcomes in such patients.

Association between myocardial work indices and cardiovascular events according to hypertension in the general population

AIMS

Pressure-strain loop (PSL) analysis is a novel echocardiographic tool capable of assessing myocardial work non-invasively. In this study, we aim to evaluate the prognostic value of myocardial work indices in the general population.

METHODS AND RESULTS

This was a prospective community-based cohort study (n = 4466). PSL analyses were performed to acquire global work index (GWI), global constructive work (GCW), global wasted work, and global work efficiency (GWE). The endpoint was a composite of heart failure or cardiovascular death (HF/CVD). Survival analysis was applied. A total of 3932 participants were included in this analysis (median age: 58 years, 43% men). Of these, 124 (3%) experienced the outcome during a median follow-up period of 3.5 years [interquartile range (IQR): 2.6-4.4 years]. Hypertension significantly modified the association between all work indices and outcome (P for interaction < 0.05), such that work indices posed a higher risk of outcome in non-hypertensive than in hypertensive participants. After adjusting for Atherosclerosis Risk in Communities (ARIC)-HF risk variables, all work indices predicted outcome in non-hypertensive participants, but only GWI, GCW, and GWE predicted outcome in hypertensive participants [GWI: hazard ratio (HR) = 1.12 (1.07-1.16), per 100 mmHg% decrease; GCW: HR = 1.12 (1.08-1.17), per 100 mmHg% decrease; GWE: HR = 1.08 (1.04-1.12), per 1% decrease]. Only GWE significantly increased C-statistics when added to ARIC-HF risk variables in hypertensive participants (C-stat 0.865 vs. 0.877, P for increment = 0.003).

CONCLUSION

Hypertension modifies the association between myocardial work indices and HF/CVD in the general population. All work indices are associated with outcome in normotensive participants. GWI, GCW, and GWE are independently associated with outcome in hypertension, but only GWE improves risk prediction.

Total-Body PET/CT Applications in Cardiovascular Diseases: A Perspective Document of the SNMMI Cardiovascular Council

Digital PET/CT systems with a long axial field of view have become available and are emerging as the current state of the art. These new camera systems provide wider anatomic coverage, leading to major increases in system sensitivity. Preliminary results have demonstrated improvements in image quality and quantification, as well as substantial advantages in tracer kinetic modeling from dynamic imaging. These systems also potentially allow for low-dose examinations and major reductions in acquisition time. Thereby, they hold great promise to improve PET-based interrogation of cardiac physiology and biology. Additionally, the whole-body coverage enables simultaneous assessment of multiple organs and the large vascular structures of the body, opening new opportunities for imaging systemic mechanisms, disorders, or treatments and their interactions with the cardiovascular system as a whole. The aim of this perspective document is to debate the potential applications, challenges, opportunities, and remaining challenges of applying PET/CT with a long axial field of view to the field of cardiovascular disease.

Longitudinal strain and myocardial work in symptomatic patients having recovered from COVID-19 and possible associations with the severity of the disease

COVID-19 may have residual consequences in multiple organs, including the cardiovascular system. The purpose of the present investigation is to quantify myocardial function in symptomatic individuals with long COVID and investigate the association between illness severity and myocardial function. A retrospective cross-sectional study was conducted in which symptomatic individuals with previous COVID-19 underwent echocardiographic analysis of left ventricle global longitudinal strain (LVGLS) and myocardial work (MW). Individuals also performed cardiopulmonary testing (CPX) to assess peak oxygen uptake (VO2peak). Differences between illness severity subgroups were analyzed by the Mann-Whitney test. Correlations were calculated using the Spearman correlation test. Multilinear regressions were performed to evaluate the influences of COVID-19 severity, body mass index, age, and sex on MW. Fifty-six individuals were included (critical subgroup: 17; moderate/severe subgroup: 39), 59% females; median age: 56 years (IQR: 43-63). CPX revealed a substantial reduction in VO2peak (median of 53% of predicted values). LVGLS were not statistically different between subgroups. Global wasted work (GWW) was higher in the critical subgroup [146 (104-212) versus 121 (74-163) mmHg%, p = 0.01], and global work efficiency (GWE) was lower in this subgroup [93 (91-95) versus 94 (93-96), p = 0.03]. Illness severity was the only independent predictor of GWW and GWE (GWW: r2 = 0.167; p = 0.009; GWE: r2 = 0.172; p = 0.005) in multilinear regressions. In our study with long COVID-19 individuals, despite having a similar LVGLS, patients had subclinical LV dysfunction, demonstrated only by an increase in GWW and a decrease in GWE.

Looking Back, Going Forward: Understanding Cardiac Pathophysiology from Pressure-Volume Loops

Knowing cardiac physiology is essential for health care professionals working in the cardiovascular field. Pressure-volume loops (PVLs) offer a unique understanding of the myocardial working and have become pivotal in complex pathophysiological scenarios, such as profound cardiogenic shock or when mechanical circulatory supports are implemented. This review provides a comprehensive summary of the left and right ventricle physiology, based on the PVL interpretation.

Energetics of Cardiac Blood Flow in Hypertrophic Cardiomyopathy through Individualized Computational Modeling

Hypertrophic cardiomyopathy (HCM) is a congenital heart disease characterized by thickening of the heart's left ventricle (LV) wall that can lead to cardiac dysfunction and heart failure. Ventricular wall thickening affects the motion of cardiac walls and blood flow within the heart. Because abnormal cardiac blood flow in turn could lead to detrimental remodeling of heart walls, aberrant ventricular flow patterns could exacerbate HCM progression. How blood flow patterns are affected by hypertrophy and inter-patient variability is not known. To address this gap in knowledge, we present here strategies to generate personalized computational fluid dynamics (CFD) models of the heart LV from patient cardiac magnetic resonance (cMR) images. We performed simulations of CFD LV models from three cases (one normal, two HCM). CFD computations solved for blood flow velocities, from which flow patterns and the energetics of flow within the LV were quantified. We found that, compared to a normal heart, HCM hearts exhibit anomalous flow patterns and a mismatch in the timing of energy transfer from the LV wall to blood flow, as well as changes in kinetic energy flow patterns. While our results are preliminary, our presented methodology holds promise for in-depth analysis of HCM patient hemodynamics in clinical practice.

Phenotyping heart failure by nuclear imaging of myocardial perfusion, metabolism, and molecular targets

Nuclear imaging techniques can detect and quantify pathophysiological processes underlying heart failure, complementing evaluation of cardiac structure and function with other imaging modalities. Combined imaging of myocardial perfusion and metabolism can identify left ventricle dysfunction caused by myocardial ischaemia that may be reversible after revascularization in the presence of viable myocardium. High sensitivity of nuclear imaging to detect targeted tracers has enabled assessment of various cellular and subcellular mechanisms of heart failure. Nuclear imaging of active inflammation and amyloid deposition is incorporated into clinical management algorithms of cardiac sarcoidosis and amyloidosis. Innervation imaging has well-documented prognostic value with respect to heart failure progression and arrhythmias. Emerging tracers specific for inflammation and myocardial fibrotic activity are in earlier stages of development but have demonstrated potential value in early characterization of the response to myocardial injury and prediction of adverse left ventricular remodelling. Early detection of disease activity is a key for transition from broad medical treatment of clinically overt heart failure towards a personalized approach aimed at supporting repair and preventing progressive failure. This review outlines the current status of nuclear imaging in phenotyping heart failure and combines it with discussion on novel developments.

Evaluating the characteristics of myocardial work by two-dimensional echocardiography during pre-eclampsia pregnancy

This study aimed to analyze the changes in myocardial work (MyW) properties and the correlation of MyW with cardiovascular and clinical indices during the pre-eclampsia (PE) pregnancy. Standard two-dimensional and speckle-tracking echocardiography were sequentially performed on 77 women with PE and 89 with normal pregnancy. Four components of MyW: global myocardial work index (GWI), constructive work (GCW), wasted work (GWW), and work efficiency (GWE) were measured. The significant increased GWI, GCW and GWW were observed, while GWW elevated more than GCW with consequently resulting the decline in GWE among PE cases. Although there was a diverse relationship between MyW components and LV morphological as well as functional indices, MyW parameters were significantly correlated with the grades of arterial hypertension and the incidence of adverse outcome of PE. With the hypertension stages, GWI, GCW and GWW gradually increased but GWE decreased. Meanwhile, the higher GWI and GCW and the lower GWE, the more adverse events occurred in PE group. In conclusion, during the PE pregnancy, GWI, GCW and GWW increase, while GWW elevates more than GCW, which leads to the decrease in GWE. Moreover, the changes in MyW are associated with the hypertension grades and the poor prognosis in PE. The non-invasive manner for MyW assessment provides a new perspective on the myocardial biomechanics, cardio-metabolic conditions and pathophysiological changes in the condition of PE.

Pulsatile energy consumption as a surrogate marker for vascular afterload improves with time post transcatheter aortic valve replacement in patients with aortic stenosis

The effect of arterial stiffening on elevated pulsatile left ventricular afterload patients with aortic stenosis (AS) is pronounced beyond systemic hypertension. Circulatory afterload pulsatile efficiency (CAPE) is a marker of vascular function, defined as the ratio of steady state energy consumption (SEC) to maintain systemic circulation and pulsatile energy consumption (PEC). Twenty patients aged 80 ± 7 years were assessed at baseline and a median of 60 days post transcatheter aortic valve replacement (TAVR), with pulsatile vascular load calculated using simultaneous radial applanation tonometry derived aortic pressure and cardiac magnetic resonance phase-contrast imaging derived ascending aortic flow. Eight out of 20 patients had a reduction in PEC post TAVR, and the reduction of PEC correlated strongly with the number of days post TAVR (R = 0.62, P < 0.01). Patients assessed within the 100 days of TAVR had a rise in their PEC when compared to baseline (0.19 ± 0.09 vs 0.14 ± 0.08 W, P = 0.04). Baseline PEC correlated moderately with baseline SEC (R = 0.49, P = 0.03), and a high baseline PEC was predictive of post TAVR PEC reduction (R = 0.54, P =0.01). Overall, no significant differences were found between baseline and post TAVR for systolic aortic pressure (131 ± 20 vs 131 ± 20 mmHg), systemic vascular resistance (1894 ± 493 vs 2015 ± 519 dynes.s/cm⁵), aortic valve ejection time (337 ± 22 vs 324 ± 34 ms) or aortic characteristic impedance (120 ± 48 vs 107 ± 41 dynes.s/cm⁵). Improved flow profiles after TAVR likely unmask the true vascular properties by altering ventriculo-valvulo-arterial coupling, leading to downstream vascular remodelling secondary to flow conditioning, and results in eventual improvement of pulsatile afterload as reflected by our proposed index of CAPE.

Inhomogeneous Distribution of Regional Myocardial Work Efficiency Predicts Early Left Ventricular Remodeling After Acute Anterior Myocardial Infarction Treated With Primary Percutaneous Intervention

Background

This study aimed to investigate the hypothesis that specific pattern of myocardial work (MW) distribution in patients with acute anterior ST-segment elevation myocardial infarction (STEMI) could provide prognostic value for predicting left ventricular (LV) remodeling.

Methods

A total of 98 first anterior wall STEMI patients treated with primary percutaneous coronary intervention [85 men (86.7%), mean age: 58 ± 12 years] were enrolled. Transthoracic echocardiography was performed 24–72 h after angioplasty and during 3-month follow-up. MW was estimated from the left ventricular pressure–strain loop derived from speckle tracking echocardiography and simultaneous noninvasive brachial artery cuff pressure. The primary endpoint was early LV remodeling, defined as an increase in LV end-diastolic volume ≥20% compared with baseline at 3 months after STEMI. Major adverse cardiac events and combined clinical outcomes were recorded.

Results

LV remodeling was present in 32 patients (33%), who exhibited lower global and culprit-regional work index (WI), constructive work (CW), work efficiency (WE), and specifically, greater differences of WE (delta-WE) and CW (delta-CW) between the culprit and non-culprit region than those without LV remodeling both at the acute phase and follow-up (all P < 0.0125). During follow-up, all global and regional WI, CW, and WE were improved (P < 0.0125 compared with baseline), with less improvement in patients with LV remodeling. In multivariate analysis, baseline delta-WE (odds ratio: 2.304; 95% CI: 1.093–4.856, P = 0.028) and peak troponin I level (odds ratio: 1.035; 95%CI: 1.008–1.063, P = 0.010) were independently associated with early LV remodeling. Patients with greater delta-WE at baseline were associated with a higher incidence of heart failure and combined clinical outcomes during follow-up.

Conclusion

After reperfused acute anterior STEMI, patients with LV remodeling presented with more inhomogeneous MW distribution. The absolute difference of WE between culprit and non-culprit territory at the acute phase is an independent predictor for early LV remodeling.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier: NCT05107102.

The Evolving Role of Echocardiography During the Coronavirus Disease 2019 Pandemic

Coronavirus disease 2019 (COVID-19) has been associated with a wide spectrum of cardiovascular manifestations. Since the beginning of the pandemic, echocardiography has served as a valuable tool for triaging, diagnosing and managing patients with COVID-19. More recently, speckle-tracking echocardiography has been shown to be effective in demonstrating subclinical myocardial dysfunction that is often not detected in standard echocardiography. Echocardiographic findings in COVID-19 patients include left or right ventricular dysfunction, including abnormal longitudinal strain and focal wall motion abnormalities, valvular dysfunction and pericardial effusion. Additionally, some of these echocardiographic abnormalities have been shown to correlate with biomarkers and adverse clinical outcomes, suggesting an additional prognostic value of echocardiography. With increasing evidence of cardiac sequelae of COVID-19, the use of echocardiography has expanded to patients with cardiopulmonary symptoms after recovery from initial infection. This article aims to highlight the available echocardiographic tools and to summarize the echocardiographic findings across the full spectrum of COVID-19 disease and their correlations with biomarkers and mortality.

Ketogenic Diet and Cardiac Substrate Metabolism

The ketogenic diet (KD) entails a high intake of fat, moderate intake of protein, and a very limited intake of carbohydrates. Ketogenic dieting has been proposed as an effective intervention for type 2 diabetes and obesity since glycemic control is improved and sustained weight loss can be achieved. Interestingly, hyperketonemia is also associated with beneficial cardiovascular effects, possibly caused by improved cardiac energetics and reduced oxygen use. Therefore, the KD has the potential to both treat and prevent cardiovascular disease. However, the KD has some adverse effects that could counteract the beneficial cardiovascular properties. Of these, hyperlipidemia with elevation of triglycerides and LDL cholesterol levels are the most important. In addition, poor diet adherence and lack of knowledge regarding long-term effects may also reduce the broader applicability of the KD. The objective of this narrative review is to provide insights into the KD and its effects on myocardial ketone body utilization and, consequently, cardiovascular health.

Changes in cardiac function following a speed ascent to the top of Europe at 4808 m

PURPOSE

Both prolonged exercise and acute high-altitude exposure are known to induce cardiac changes. We sought to describe the cardiac responses to speed climbing at high-altitude, including left ventricular (LV) performance assessment using the myocardial work index (MWI), a new index derived from 2D speckle tracking echocardiography (STE).

METHODS

Eleven elite alpinists (9 males, age: 26 ± 4 years) were evaluated before and immediately after a speed ascent of the Mont-Blanc (4808 m) by echocardiography using conventional measurements as well as STE and MWI computation with derivate parameters as global work efficiency (GWE) or global wasted work (GWW).

RESULTS

Athletes performed a long-duration (8 h 58 min ± 60 min) and intense (78 ± 4% of maximal heart rate) ascent under gradual hypoxic conditions (minimal SpO₂ at 4808 m: 71 ± 4%). Hypoxic exercise-induced cardiac fatigue was observed post-ascent with a change in right ventricular (RV) and LV systolic function (RV fractional area change: - 20 ± 23%, p = 0.01; LV global longitudinal strain change: - 8 ± 9%, p = 0.02), as well as LV geometry and RV-LV interaction alterations with emergence of a D-shape septum in 5/11 (46%) participants associated with RV pressure overload (mean pulmonary arterial pressure change: + 55 ± 20%, p < 0.001). Both MWI and GWE were reduced post-ascent (- 21 ± 16%, p = 0.004 and - 4 ± 4%, p = 0.007, respectively). Relative decrease in MWI and GWE were inversely correlated with increase in GWW (r = - 0.86, p = 0.003 and r = -0.97, p < 0.001, respectively).

CONCLUSIONS

Prolonged high-altitude speed climbing in elite climbers is associated with RV and LV function changes with a major interaction alteration. MWI, assessing the myocardial performance, could be a new tool for evaluating LV exercise-induced cardiac fatigue.

Obstructive sleep apnea is associated with depressed myocardial mechanoenergetics

PURPOSE

To evaluate the association between the myocardial mechanoenergetic efficiency index (MEEi) and the Apnea-Hypopnea Index (AHI) in the initial phase of obstructive sleep apnea (OSA) diagnosis.

METHODS

In this cohort study, we included a total of 382 eligible participants without cardiovascular disease in a tertiary outpatient clinic between January 2013 and January 2015. We recorded demographic, clinical, polysomnographic and echocardiographic variables of the patients. In addition, myocardial mechanoenergetic efficiency (MEE) and MEEi were calculated by an echocardiography-derived validated measurement.

RESULTS

The mean (±SD) age of the participants was 48.47 ± 12.13, and male/female ratio was 287/95. Comparing with non-OSA, MEEi was significantly lower in OSA patients at all stages (0.35 ± 0.08 vs. 0.42 ± 0.05; p < .001). MEEi was negatively correlated with hypertension (r = -0.518, p < .001), body mass index (r = -0.382, p < .001), AHI (r = -0.656, p < .001), total apne (r = -0.525, p < .001), hypopnea (r = -0.415, p < .001), systolic pulmonary pressure (r = -0.318, p < .001), relative wall thickness (RWT; r = -0.415, p < .001), and positive correlated with left ventricular ejection fraction (r = 0.586, p < .001). According to multiple linear regression analysis AHI (β = -0.625, p < .001), total apnea (β = -0.402, p = .001), hypopnea (β = -0.395, p = .001), LV ejection fraction (β = 0.478, p < .001) and RWT (β = -0.279, p < .001) have an independent relationship with MEEi.

CONCLUSIONS

MEEi was lower in OSA patients. A reduced MEEi may reflect a disturbance in energy use of the myocardium. Consequently, our results may provide insight into the mechanisms leading to structural cardiac diseases in OSA patients.

Evaluation of Non-infarct-Related Arteries Using C-11 Acetate PET in STEMI With Multivessel Disease

BACKGROUND

We analyzed whether C-11 acetate positron emission tomography (PET) can be used for the evaluation of non-infarct-related artery (NIRA) in patients with ST-elevation myocardial infarction (STEMI) and multivessel disease.

METHODS

We prospectively enrolled 31 patients with STEMI and at least one NIRA stenosis (diameter stenosis [DS] ≥ 50%). C-11 acetate PET was performed after successful revascularization for the infarct-related artery (IRA). Myocardial blood flow (MBF) and oxidative metabolism (k_mono) were measured and compared between NIRA vs. IRA, stenotic (DS ≥ 50%) vs. non-stenotic (DS < 50%) NIRAs, and NIRAs with significant stenosis (DS ≥ 70% or fractional flow reserve [FFR] ≤ 0.80) vs. those without (neither DS ≥ 70% nor FFR ≤ 0.80). The correlations between PET and angiographic parameters were also analyzed.

RESULTS

MBF and k_mono were significantly higher in NIRAs than those in IRAs. Stenotic NIRAs showed significantly reduced stress MBF, myocardial flow reserve (MFR), relative flow reserve (RFR) (0.72 ± 0.12 vs. 0.82 ± 0.14; p = 0.001), and stress k_mono, as compared to those in non-stenotic NIRAs. NIRAs with significant stenosis had significantly lower stress MBF, MFR, and RFR (0.70 ± 0.10 vs. 0.80 ± 0.14; p = 0.001). RFR showed the best, but modest linear correlation with DS of NIRA stenosis (r = −0.429, p = 0.001). RFR > 0.81 could effectively exclude the presence of significant NIRA stenosis.

CONCLUSIONS

C-11 acetate PET could be a feasible alternative noninvasive modality in patients with STEMI and multivessel disease, by excluding the presence of significant NIRA stenosis.

Myocardial efficiency in patients with different aetiologies and stages of heart failure

AIMS

Myocardial external efficiency (MEE) is the ratio of cardiac work in relation with energy expenditure. We studied MEE in patients with different aetiologies and stages of heart failure (HF) to discover the role and causes of deranged MEE. In addition, we explored the impact of patient characteristics such as sex, body mass index (BMI), and age on myocardial energetics.

METHODS AND RESULTS

Cardiac energetic profiles were assessed with 11C-acetate positron emission tomography (PET) and left ventricular ejection fraction (LVEF) was acquired with echocardiography. MEE was studied in 121 participants: healthy controls (n = 20); HF patients with reduced (HFrEF; n = 25) and mildly reduced (HFmrEF; n = 23) LVEF; and patients with asymptomatic (AS-asymp; n = 38) and symptomatic (AS-symp; n = 15) aortic stenosis (AS). Reduced MEE coincided with symptoms of HF irrespective of aetiology and declined in tandem with deteriorating LVEF. Patients with AS-symp and HFmrEF had reduced MEE as compared with controls (22.2 ± 4.9%, P = 0.041 and 20.0 ± 4.2%, P < 0.001 vs. 26.1 ± 5.8% in controls) and a further decline was observed in patients with HFrEF (14.7 ± 6.3%, P < 0.001). Disproportionate left ventricular hypertrophy was a major cause of reduced MEE. Female sex (P < 0.001), a lower BMI (P = 0.001), and advanced age (P = 0.03) were associated with a lower MEE.

CONCLUSION

MEE was reduced in patients with HFrEF, HFmrEF, and HF due to pressure overload and MEE may therefore constitute a treatment target in HF. Patients with LVH, advanced age, female sex, and low BMI had more pronounced reduction in MEE and personalized treatment within these patient subgroups could be relevant.

Dynamics of Left Ventricular Myocardial Work in Patients Hospitalized for Acute Heart Failure

BACKGROUND

The left ventricular ejection fraction (LVEF) is the most commonly used measure describing pumping efficiency, but it is heavily dependent on loading conditions and therefore not well-suited to study pathophysiologic changes. The novel concept of echocardiography-derived myocardial work (MyW) overcomes this disadvantage as it is based on LV pressure-strain loops. We tracked the in-hospital changes of indices of MyW in patients admitted for acute heart failure (AHF) in relation to their recompensation status and explored the prognostic utility of MyW indices METHODS AND RESULTS: We studied 126 patients admitted for AHF (mean 73 ± 12 years, 37% female, 40% with a reduced LVEF [<40%]), providing pairs of echocardiograms obtained both on hospital admission and prior to discharge. The following MyW indices were derived: global constructive and wasted work (GCW, GWW), global work index (GWI), and global work efficiency. In patients with HF with reduced ejection fraction with decreasing N-terminal prohormone B-natriuretic peptide levels during hospitalization, the GCW and GWI improved significantly, whereas the GWW remained unchanged. In patients with HF with preserved ejection fraction, the GCW and GWI were unchanged; however, in patients with no decrease or eventual increase in N-terminal prohormone B-natriuretic peptide, we observed an increase in GWW. In all patients with AHF, higher values of GWW were associated with a higher risk of death or rehospitalization within 6 months after discharge (per 10-point increment hazard ratio 1.035, 95% confidence interval 1.005-1.065).

CONCLUSIONS

Our results suggest differential myocardial responses to decompensation and recompensation, depending on the HF phenotype in patients presenting with AHF. The GWW predicted the 6-month prognosis in these patients, regardless of LVEF. Future studies in larger cohorts need to confirm our results and identify determinants of short-term and longer term changes in MyW.

Myocardial Work Efficiency, A Novel Measure of Myocardial Dysfunction, Is Reduced in COVID-19 Patients and Associated With In-Hospital Mortality

Background: Although troponin elevation is common in COVID-19, the extent of myocardial dysfunction and its contributors to dysfunction are less well-characterized. We aimed to determine the prevalence of subclinical myocardial dysfunction and its association with mortality using speckle tracking echocardiography (STE), specifically global longitudinal strain (GLS) and myocardial work efficiency (MWE). We also tested the hypothesis that reduced myocardial function was associated with increased systemic inflammation in COVID-19. Methods and Results: We conducted a retrospective study of hospitalized COVID-19 patients undergoing echocardiography (n = 136), of whom 83 and 75 had GLS (abnormal >-16%) and MWE (abnormal <95%) assessed, respectively. We performed adjusted logistic regression to examine associations of GLS and MWE with in-hospital mortality. Patients were mean 62 ± 14 years old (58% men). While 81% had normal left ventricular ejection fraction (LVEF), prevalence of myocardial dysfunction was high by STE; [39/83 (47%) had abnormal GLS; 59/75 (79%) had abnormal MWE]. Higher MWE was associated with lower in-hospital mortality in unadjusted [OR 0.92 (95% CI 0.85-0.99); p = 0.048] and adjusted models [aOR 0.87 (95% CI 0.78-0.97); p = 0.009]. In addition, increased systemic inflammation measured by interleukin-6 level was associated with reduced MWE. Conclusions: Subclinical myocardial dysfunction is common in COVID-19 patients with clinical echocardiograms, even in those with normal LVEF. Reduced MWE is associated with higher interleukin-6 levels and increased in-hospital mortality. Non-invasive STE represents a readily available method to rapidly evaluate myocardial dysfunction in COVID-19 patients and can play an important role in risk stratification.

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.

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.