A new integrated approach to cardiac mechanics: reference values for normal left ventricle

2D speckle-tracking echocardiography assessment of left atrial and left ventricular mechanics: outcomes in patients with atrial fibrillation treated with hybrid ablation and left atrial appendage surgical closure

Background and aims

Hybrid atrial fibrillation (AF) ablation is a therapeutic option in non-paroxysmal AF. Our study examines cardiac mechanics changes after hybrid AF ablation plus epicardial closure of left atrial appendage (LAA).

Methods

All consecutive patients undergoing hybrid AF ablation at UZ Brussel were evaluated. They received pulmonary vein isolation (PVI), posterior wall isolation (LAPWI), and epicardial LAA closure. Left atrium (LA) and Left ventricle (LV) mechanics were analyzed, with the following measures obtained at baseline, post-ablation, and follow-up: 1) volumes (EDV, ESV); 2) ejection fraction (EF); 3) strain (ENDO GCS, ENDO GLS); 4) forces (LVLF, LVsysLF, LVim, LVs).

Results

A total of 50 patients were included. At follow-up, LAEDV decreased from baseline [44.7 mL vs 53.8 mL, P = 0.025]. LA ENDO GCS and GLS increased post-ablation, with further GLS improvement at follow-up. LV ENDO GCS and LV ENDO GLS also rose post-ablation [-26.7% vs. -22.5%, P < 0.001] and [-20.57% vs. -16.6%, P < 0.001], respectively. LVEF increased post-ablation [54.6% vs 46.3%, P < 0.001]. There was an increase in all LV hemodynamic forces (HDFs) and in particular: LVLF and LVsysLF increased post-ablation [15.5% vs 10.4%, P < 0.001] and [21.5% vs 14.11%, P < 0.001], respectively. LVim also increased post-ablation [19.6% vs 12.8%, P < 0.001]. Finally, there was an increase in LVs post-ablation compared to baseline [10.6% vs 5.4%, P < 0.001].

Conclusion

In patients undergoing hybrid AF ablation, there was a significant and persistent improvement in the mechanical and hemodynamic functions of both LA and LV.

Hemodynamic Force Based on Cardiac Magnetic Resonance Imaging: State of the Art and Perspective

Intracardiac blood flow has long been proposed to play a significant role in cardiac morphology and function. However, absolute blood pressure within the heart has mainly been measured by invasive catheterization, which limits its application. Hemodynamic force (HDF) is the global force of intracavitary blood flow acquired by integrating the intraventricular pressure gradient over the entire ventricle and thus may be a promising tool for accurately characterizing cardiac function. Recent advances in magnetic resonance imaging technology allow for a noninvasive measurement of HDF through both 4D flow cardiac MRI and cine cardiac MRI. The HDF time curve provides comprehensive data for both qualitative and quantitative analysis. In this review, a series of HDF parameters is introduced and a summary of the current literature regarding HDF in clinical practice is presented. Additionally, the current dilemmas and future prospects are discussed in order to contribute to the future research. LEVEL OF EVIDENCE: 5. TECHNICAL EFFICACY: Stage 2.

Left Ventricular Hemodynamic Forces Changes in Fabry Disease: A Cardiac Magnetic Resonance Study

BACKGROUND

Hemodynamic force (HDF) from cardiac MRI can indicate subclinical myocardial dysfunction, and help identify early cardiac changes in patients with Fabry disease (FD). The hemodynamic change in FD patients remains unclear.

PURPOSE

To explore HDF changes in FD and the potential of HDF measurements as diagnostic markers indicating early cardiac changes in FD.

STUDY TYPE

Single-center, prospective, observational study.

POPULATION

Forty-six FD patients (age: 38 ± 12, females: 45.65%) and 46 sex- and age-matched healthy controls (HCs).

FIELD STRENGTH/SEQUENCE

3 T, cardiac MRI including steady-state free precession cine imaging (during multiple breath-holds), phase-sensitive inversion recovery sequence for late gadolinium enhancement (LGE) imaging, and motion-corrected modified Look-Locker inversion recovery sequence for T1 mapping.

ASSESSMENT

Analysis of strains and HDF were performed on the cine imaging. HDF parameters includes apical-basal force, systolic impulse, systolic peak, systolic-diastolic transition, diastolic deceleration, and atrial thrust. Moreover, FD patients were categorized with left ventricular hypertrophy (LVH+) (the maximal wall thickness >12 mm) or without LVH (LVH-). Mainz Severity Score Index (MSSI) score was calculated to measure the progression of FD.

STATISTICAL TESTS

Group comparison tests, logistic regression, and receiver operating characteristic curve (ROC) were performed. A P-value <0.05 was considered statistically significant.

RESULTS

FD patients showed significantly lower native T1 (1161.1 ± 55.4 vs. 1202.8 ± 42.0 msec) and higher systolic impulse (33.8 ± 9.9 vs. 24.8 ± 9.5%). The systolic impulse in HDF analysis increased even in the pre-hypertrophic stage. The increased myocardial global longitudinal strain (r = 0.419) and systolic impulse (r = 0.333) showed positive correlations with a higher MSSI score. The AUC of systolic impulse and global native T1 showed no significant difference (0.764 vs. 0.790, P = 0.784).

DATA CONCLUSION

Increased systolic impulse and systolic peak can be observed in FD patients. Systolic impulse showed potential ability for screening pre-LVH FD patients and correlated with disease severity in FD patients.

PLAIN LANGUAGE SUMMARY

This study explored hemodynamic changes in patients with Fabry disease (FD) using hemodynamic force (HDF) analysis based on cardiac MRI. 46 FD patients were included and analysis of cardiac function, native T1, strains, and hemodynamic changes on cardiac MRI images were performed. The results showed that systolic impulse and systolic peak of HDF analysis were increased in FD patients, and systolic impulse may increase even in the pre-hypertrophic stage. Systolic impulse was correlated with disease severity in patients with FD, which may be a potential image-based diagnosis and monitoring marker in FD patients.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Differences in cardiac mechanics assessed by left ventricular hemodynamic forces in athletes and patients with hypertension

We sought to assess cardiac magnetic resonance derived left ventricular hemodynamic forces (HDF) in athletes compared to patients with hypertension. Sixty athletes and 48 hypertensive patients were studied. HDF were measured during the entire cardiac cycle, the systolic phase, suction, early LV filling, and atrial thrust. Statistical comparisons were made between athletes and hypertensive patients, and between endurance and strength athletes. The slope of the systolic ejection was higher in athletes compared to hypertensive patients (541.5 vs. 435 1/sec; p = 0.033). Athletes showed higher HDF during the first phase of systole (4.53 vs. 3.86; p = 0.047) and the systolic impulse (11.26 vs. 8.76; p = 0.045). Compared to hypertensive patients, the AUC of the elastic rebound in athletes was lower (-0.31 vs. -0.44; p = 0.011). Moreover, hypertensive patients had an abnormal suction as revealed by a divergent direction (apex-to-base) of the HDF. The atrial thrust was higher in hypertensive patients than in athletes (-0.31 vs. -0.05; p < 0.001). Compared to endurance athletes, strength athletes had a shorter duration of the systolic impulse (250 vs. 280 ms; p = 0.019) and higher AUC during the early LV filling (1.65 vs. 0.97; p = 0.016). We conclude that HDF allows distinction between the hemodynamic patterns of athletes and patients with hypertension.

Assessing cardiac mechanics through left ventricular haemodynamic forces

Haemodynamic forces (HDFs), which represent the forces exchanged between blood and surrounding tissues, are critical in regulating the structure and function of the left ventricle (LV). These forces can be assessed on cardiac magnetic resonance or transthoracic echocardiography exams using specialized software, offering a non-invasive alternative for measuring intraventricular pressure gradients. The analysis of HDFs can be a valuable tool in improving our understanding of cardiovascular disease and providing insights beyond traditional diagnostic and therapeutic approaches. For instance, HDF analysis has the potential to identify early signs of adverse remodelling and cardiac dysfunction, which may not be detected by standard imaging methods such as bidimensional or speckle-tracking echocardiography. This review aims to summarize the principles of HDF analysis and to reappraise its possible applications to cardiac disorders.

Echocardiography-Derived Hemodynamic Forces Are Associated with Clinical Outcomes in Patients with Non-Ischemic Dilated Cardiomyopathy

Introduction: Non-ischemic dilated cardiomyopathy (NIDCM) is characterized by a reduced left ventricular (LV) ejection fraction (LVEF, <50%) and a high risk for heart failure (HF) and death. Echocardiography-derived hemodynamic forces (HDFs) may provide important information on LV mechanics, but their prognostic value is unknown. Aim: To explore the features of echocardiography-derived HDFs in NIDCM and their association with clinical endpoints. Methods: Asymptomatic, non-hospitalized NIDCM patients free from coronary artery disease and moderate or severe valvular heart disease were included in this single-center observational retrospective longitudinal study. Those with atrial fibrillation and a follow-up <12 months were excluded. Major adverse cardiovascular events (MACE) were defined as a composite of all-cause death, HF hospitalization, and ambulatory intravenous diuretics administration. LV HDFs were analyzed with a prototype software. Apex-base (HDFs-ab), lateral-septal (HDFs-ls), and HDFs-angle were computed. Results: Ninety-seven patients were included, sixty-seven (69%) were males, mean age was 62 ± 14 years, and mean LVEF was 39.2 ± 8.6%. During a median follow-up of 4.2 (3.1-5.1) years, 19 (20%) patients experienced MACE. These patients had a higher HDFs-angle (71.0 (67.0-75.0) vs. 68.0 (63.0-71.0)°, p = 0.005), lower HDFs-ls (1.36 (1.01-1.85) vs. 1.66 ([1.28-2.04])%, p = 0.015), but similar HDFs-ab (5.02 (4.39-6.34) vs. 5.66 (4.53-6.78)%, p = 0.375) compared to those without MACE. in a Cox regression analysis, HDFs-angle (HR 1.16 (95%-CI 1.04-1.30), p = 0.007) was associated with MACE, while other conventional echocardiography parameters, including LVEF and LV longitudinal strain, were not. Conclusions: HDFs-angle is associated with clinical endpoints in NIDCM. A higher HDFs-angle may be a marker of impaired myocardial performance in patients with reduced LVEF.

Unravelling the intricacies of left ventricular haemodynamic forces: age and gender-specific normative values assessed by cardiac MRI in healthy adults

AIMS

Haemodynamic forces (HDFs) provided a feasible method to early detect cardiac mechanical abnormalities by estimating the intraventricular pressure gradients. The novel advances in assessment of HDFs using routine cardiac magnetic resonance (CMR) cines shed new light on detection of preclinical dysfunction. However, definition of normal values for this new technique is the prerequisite for application in the clinic.

METHODS AND RESULTS

A total of 218 healthy volunteers [38.1 years ± 11.1; 111 male (50.9%)] were recruited and underwent CMR examinations with a 3.0T scanner. Balanced steady state free precession breath hold cine images were acquired, and HDF assessments were performed based on strain analysis. The normal values of longitudinal and transversal HDF strength [root mean square (RMS)] and ratio of transversal to longitudinal HDF were all evaluated in overall population as well as in both genders and in age-specific groups. The longitudinal RMS values (%) of HDFs were significantly higher in women (P < 0.05). Moreover, the HDF amplitudes significantly decreased with ageing in entire heartbeat, systole, diastole, systolic/diastolic transition, and diastolic deceleration, while increased in atrial thrust. In multivariable linear regression analysis, age, heart rate, and global longitudinal strain emerged as independent predictors of the amplitudes of longitudinal HDFs in entire heartbeat and systole, while left ventricular end-diastole volume index was also independently associated with longitudinal HDFs in diastole and diastolic deceleration (P < 0.05 for all).

CONCLUSION

Our study provided comprehensive normal values of HDF assessments using CMR as well as presented with specific age and sex stratification. HDF analyses can be performed with excellent intra- and inter-observer reproducibility.

Inter-study reproducibility of cardiovascular magnetic resonance-derived hemodynamic force assessments

Cardiovascular magnetic resonance (CMR)-derived hemodynamic force (HDF) analyses have been introduced recently enabling more in-depth cardiac function evaluation. Inter-study reproducibility is important for a widespread clinical use but has not been quantified for this novel CMR post-processing tool yet. Serial CMR imaging was performed in 11 healthy participants in a median interval of 63 days (range 49-87). HDF assessment included left ventricular (LV) longitudinal, systolic peak and impulse, systolic/diastolic transition, diastolic deceleration as well as atrial thrust acceleration forces. Inter-study reproducibility and study sample sizes required to demonstrate 10%, 15% or 20% relative changes of HDF measurements were calculated. In addition, intra- and inter-observer analyses were performed. Intra- and inter-observer reproducibility was excellent for all HDF parameters according to intraclass correlation coefficient (ICC) values (> 0.80 for all). Inter-study reproducibility of all HDF parameters was excellent (ICC ≥ 0.80 for all) with systolic parameters showing lower coeffients of variation (CoV) than diastolic measurements (CoV 15.2% for systolic impulse vs. CoV 30.9% for atrial thrust). Calculated sample sizes to detect relative changes ranged from n = 12 for the detection of a 20% relative change in systolic impulse to n = 200 for the detection of 10% relative change in atrial thrust. Overall inter-study reproducibility of CMR-derived HDF assessments was sufficient with systolic HDF measurements showing lower inter-study variation than diastolic HDF analyses.

Impact of left ventricular hemodynamic forces in adult patients with treated aortic coarctation and preserved left ventricular systolic function

BACKGROUND

The LV myocardial strain and hemodynamic forces (HDFs) are innovative markers of LV function. Aortic coarctation is safely repaired in infancy; however, mortality and morbidity remain increased in later life. The study investigated the role of left ventricular myocardial deformation and HDFs in asymptomatic patients who underwent successful aortic coarctation repair.

METHODS

Clinical and echocardiographic data were analyzed from 42 repaired CoA, 32 ± 20 years after surgery, 2D echocardiographic global longitudinal strain (GLS), circumferential strain (GCS) and HDFs were determined. CoA patients were compared with 42 patients affected by blood hypertension and 84 healthy controls; all matched for age and gender.

RESULTS

All groups had normal LV ejection fraction (LVEF), dimensions, and volumes. CoA patients showed a significantly higher rate of LV mass indexed (p < .001) and left atrial volumes indexed (p < .001). LV myocardial and endocardial global longitudinal and circumferential strain were decreased in CoA patients (p < .001, p < .001; p = .032 and p < .001, respectively). HDF parameters such as LV longitudinal force, LV systolic longitudinal force and LV impulse (LVim) were uniformly reduced (p = .006, p = .001, and p = .001, respectively). LV myocardial strain and HDF parameter values were independently associated with hospitalization for heart failure on univariable Cox regression analysis.

CONCLUSION

Despite preserved LVEF, patients with CoA had lower LV myocardial strain and HDF parameters values, independently associated with hospitalization for heart failure.

Haemodynamic forces predicting remodelling and outcome in patients with heart failure treated with sacubitril/valsartan

AIMS

A novel tool for the evaluation of left ventricular (LV) systo-diastolic function through echo-derived haemodynamic forces (HDFs) has been recently proposed. The present study aimed to assess the predictive value of HDFs on (i) 6 month treatment response to sacubitril/valsartan in heart failure with reduced ejection fraction (HFrEF) patients and (ii) cardiovascular events.

METHODS AND RESULTS

Eighty-nine consecutive HFrEF patients [70% males, 65 ± 9 years, LV ejection fraction (LVEF) 27 ± 7%] initiating sacubitril/valsartan underwent clinical, laboratory, ultrasound and cardiopulmonary exercise testing evaluations. Patients experiencing no adverse events and showing ≥50% reduction in plasma N-terminal pro-B-type natriuretic peptide and/or ≥10% LVEF increase over 6 months were considered responders. Patients were followed up for the composite endpoint of HF-related hospitalisation, atrial fibrillation and cardiovascular death. Forty-five (51%) patients were responders. Among baseline variables, only HDF-derived whole cardiac cycle LV strength (wLVS) was higher in responders (4.4 ± 1.3 vs. 3.6 ± 1.2; p = 0.01). wLVS was also the only independent predictor of sacubitril/valsartan response at multivariable logistic regression analysis [odds ratio 1.36; 95% confidence interval (CI) 1.10-1.67], with good accuracy at receiver operating characteristic (ROC) analysis [optimal cutpoint: ≥3.7%; area under the curve (AUC) = 0.736]. During a 33 month (23-41) median follow-up, a wLVS increase after 6 months (ΔwLVS) showed a high discrimination ability at time-dependent ROC analysis (optimal cut-off: ≥0.5%; AUC = 0.811), stratified prognosis (log-rank p < 0.0001) and remained an independent predictor for the composite endpoint (hazard ratio 0.76; 95% CI 0.61-0.95; p < 0.01), after adjusting for clinical and instrumental variables.

CONCLUSIONS

HDF analysis predicts sacubitril/valsartan response and might optimise decision-making in HFrEF patients.

Prognostic value of echocardiographic evaluation of cardiac mechanics in patients with aortic stenosis and preserved left ventricular ejection fraction

Left ventricular ejection function (LVEF) is not reliable in identifying subtle systolic dysfunction. Speckle Tracking (ST) plays a promising role and hemodynamic forces (HDFs) are emerging as marker of LV function. The role of LV myocardial deformation and HDFs was investigated in a cohort of patients with aortic stenosis (AS) and normal LVEF. Two hundred fifty three patients (median age 79 years, IQR 73 - 83 years) with mild (n = 87), moderate (n =77) and severe AS (n =89) were retrospectively enrolled. 2D echocardiographic global longitudinal strain (GLS), circumferential strain (GCS) and HDFs were determined. The worsening of AS was associated with raising inappropriate LV mass (p < 0.001) and declined LVEF, despite being in the normal range (p < 0.001). ST and HDFs parameters declined as the AS became severe (p<0.0001, for all). When patients were grouped based on the median of LV endocardial GLS value (> -19,9%) and LV systolic longitudinal force (LVsysLF) value (< 12,49), patients with impaired ST and lower HDFs components had increased incidence of aortic valve replacement (AVR) and worse survival (p <0.024 and p <0.037, respectively). Among ST and HDFs parameters, only LVsysLF was independently associated with AVR and all causes mortality on multivariable Cox regression analysis (HR 0.94; 95% CI 0.89-0.99; p= 0.012). Reduced values of LVsysLF were associated with AVR and reduced survival in AS patients. LVsysLF could provide useful information in the stratification of patients with AS and possibly in the choice of timing for AVR.

Acute Modification of Hemodynamic Forces in Patients with Severe Aortic Stenosis after Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) is the established first-line treatment for patient with severe aortic stenosis not suitable for surgery. Echocardiographic evaluation of hemodynamic forces (HDFs) is a growing field, holding the potential to early predict improvement in LV function. A prospective observational study was conducted. Transthoracic echocardiography was performed before and after TAVI. HDFs were analyzed along with traditional left ventricular (LV) function parameters. Twenty-five consecutive patients undergoing TAVI were enrolled: mean age 83 ± 5 years, 74.5% male, mean LV Ejection Fraction (LVEF) at baseline 57 ± 8%. Post-TAVI echocardiographic evaluation was performed 2.4 ± 1.06 days after the procedure. HDF amplitude parameters improved significantly after the procedure: LV Longitudinal Forces (LF) apex-base [mean difference (MD) 1.79%; 95% CI 1.07-2.5; p-value < 0.001]; LV systolic LF apex-base (MD 2.6%; 95% CI 1.57-3.7; p-value < 0.001); LV impulse (LVim) apex-base (MD 2.9%; 95% CI 1.48-4.3; p-value < 0.001). Similarly, HDFs orientation parameters improved: LVLF angle (MD 1.5°; 95% CI 0.07-2.9; p-value = 0.041); LVim angle (MD 2.16°; 95% CI 0.76-3.56; p-value = 0.004). Conversely, global longitudinal strain and LVEF did not show any significant difference before and after the procedure. Echocardiographic analysis of HDFs could help differentiate patients with LV function recovery after TAVI from patients with persistent hemodynamic dysfunction.

Introduction to hemodynamic forces by echocardiography

Hemodynamic force (HDF) analysis represents a novel approach to quantify intraventricular pressure gradients, responsible for blood flow. A new mathematical model allows the derivation of HDF parameters from routine transthoracic echocardiography, making this tool more accessible for clinical use. HDF analysis is considered the fluid dynamics correlate of deformation imaging and may be even more sensitive to detect mechanical abnormalities. This has the potential to add incremental clinical value, allowing earlier detection of pathology or immediate evaluation of response to treatment. In this article, the theoretical background and physiological patterns of HDF in the left ventricle are provided. In pathological situations, the HDF pattern might alter, which is illustrated with a case of ST segment elevation myocardial infarction and non-ischemic cardiomyopathy with typical left bundle branch block.

Age-, Sex-, and Race-Based Normal Values for Left Ventricular Circumferential Strain from the World Alliance Societies of Echocardiography Study

BACKGROUND

Left ventricular (LV) circumferential strain has received less attention than longitudinal deformation, which has recently become part of routine clinical practice. Among other reasons, this is because of the lack of established normal values. Accordingly, the aim of this study was to establish normative values for LV circumferential strain and determine sex-, age-, and race-related differences in a large cohort of healthy adults.

METHODS

Complete two-dimensional transthoracic echocardiograms were obtained in 1,572 healthy subjects (51% men), enrolled in the World Alliance Societies of Echocardiography Normal Values Study. Subjects were divided into three age groups (<35, 35-55, and >55 years) and stratified by sex and by race. Vendor-independent semiautomated speckle-tracking software was used to determine LV regional circumferential strain and global circumferential strain (GCS) values. Limits of normal for each measurement were defined as 95% of the corresponding sex and age group falling between the 2.5th and 97.5th percentiles. Intergroup differences were analyzed using unpaired t tests.

RESULTS

Circumferential strain showed a gradient, with lower magnitude at the mitral valve level, increasing progressively toward the apex. Compared with men, women had statistically higher magnitudes of regional and global strain. Older age was associated with a stepwise increase in GCS despite an unaffected ejection fraction, a decrease in LV volume, and relatively stable global longitudinal strain in men, with a small gradual decrease in women. Asian subjects demonstrated significantly higher GCS magnitudes than whites of both sexes and blacks among women only. In contrast, no significant differences in GCS were found between white and black subjects of either sex. Importantly, despite statistical significance of these differences across sex, age, and race, circumferential strain values were similar in all groups, with variations of the order of magnitude of 1% to 2%. Notably, no differences in GCS were found among brands of imaging equipment.

CONCLUSION

This study established normal values of LV regional circumferential strain and GCS and identified sex-, age-, and race-related differences when present.

Hemodynamic force assessment by cardiovascular magnetic resonance in HFpEF: A case-control substudy from the HFpEF stress trial

BACKGROUND

The diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging. Exercise-stress testing is recommended in case of uncertainty; however, this approach is time-consuming and costly. Since preserved EF does not represent normal systolic function, we hypothesized comprehensive cardiovascular magnetic resonance (CMR) assessment of cardiac hemodynamic forces (HDF) may identify functional abnormalities in HFpEF.

METHODS

The HFpEF Stress Trial (DZHK-17; Clinicaltrials.gov: NCT03260621) prospectively recruited 75 patients with exertional dyspnea, preserved EF (≥50%) and signs of diastolic dysfunction (E/e' ≥8) on echocardiography. Patients underwent rest and exercise-stress right heart catheterisation, echocardiography and CMR. The final study cohort consisted of 68 patients (HFpEF n = 34 and non-cardiac dyspnea n = 34 according to pulmonary capillary wedge pressure (PCWP)). HDF assessment included left ventricular (LV) longitudinal, systolic peak and impulse, systolic/diastolic transition, E-wave deceleration as well as A-wave acceleration forces. Follow-up after 24 months evaluated cardiovascular mortality and hospitalisation (CVH) - only two patients were lost to follow-up.

FINDINGS

HDF assessment revealed impairment of LV longitudinal function in patients with HFpEF compared to non-cardiac dyspnoea (15.8% vs. 18.3%, p = 0.035), attributable to impairment of systolic peak (38.6% vs 51.6%, p = 0.003) and impulse (20.8% vs. 24.5%, p = 0.009) forces as well as late diastolic filling (-3.8% vs -5.4%, p = 0.029). Early diastolic filling was impaired in HFpEF patients identified at rest compared with patients identified during stress only (7.7% vs. 9.9%, p = 0.004). Impaired systolic peak was associated with CVH (HR 0.95, p = 0.016), and was superior to LV global longitudinal strain assessment in prediction of CVH (AUC 0.76 vs. 0.61, p = 0.048).

INTERPRETATION

Assessment of HDF indicates impairment of LV systolic ejection force in HFpEF which is associated with cardiovascular events.

FUNDING

German Centre for Cardiovascular Research (DZHK).

Acute coronary syndrome versus acute myocarditis in young adults–value of speckle tracking echocardiography

Purpose

Comparing myocarditis with an acute coronary syndrome (ACS)-like presentation and acute myocardial infarction (AMI) poses an important clinical challenge. The purpose of the study was to investigate the diagnostic value of the clinical, laboratory and especially echocardiographic characteristics including speckle tracking echocardiography (STE) of patients with ACS-like myocarditis and AMI.

Methods

We conducted a retrospective analysis comparing 69 symptomatic patients (≤ 45 years old), hospitalized at the Department of Interventional Cardiology (Medical University of Lodz, Poland) between April 2014 and June 2021 with an initial diagnosis of ST-segment elevation myocardial infarction.

Results

37 patients with the cardiac magnetic resonance–confirmed acute myocarditis and 32 patients diagnosed with AMI based on the clinical presentation, electrocardiogram and the presence of a culprit lesion on the coronary angiography were analysed including echocardiography parameters. On STE analysis an average global longitudinal (GLS), radial and circumferential strain including three—layers observation were significantly lower (absolute value) in patients with AMI versus acute myocarditis (p<0.05). There was no significant difference in Endo/Epi ratio (p = 0.144) between the groups. An average GLS < (-17.5) represented the optimal cut-off value for the myocarditis diagnosis.

Conclusion

In patients with AMI a significant reduction of global and three-layers strains compared to patients with myocarditis was detected. Furthermore, our analysis also confirmed the discriminative pattern of myocardial injury between the groups.

Surrogate models provide new insights on metrics based on blood flow for the assessment of left ventricular function

Recent developments on the grading of cardiac pathologies suggest flow-related metrics for a deeper evaluation of cardiac function. Blood flow evaluation employs space-time resolved cardiovascular imaging tools, possibly integrated with direct numerical simulation (DNS) of intraventricular fluid dynamics in individual patients. If a patient-specific analysis is a promising method to reproduce flow details or to assist virtual therapeutic solutions, it becomes impracticable in nearly-real-time during a routine clinical activity. At the same time, the need to determine the existence of relationships between advanced flow-related quantities of interest (QoIs) and the diagnostic metrics used in the standard clinical practice requires the adoption of techniques able to generalize evidences emerging from a finite number of single cases. In this study, we focus on the left ventricular function and use a class of reduced-order models, relying on the Polynomial Chaos Expansion (PCE) technique to learn the dynamics of selected QoIs based on a set of synthetic cases analyzed with a high-fidelity model (DNS). The selected QoIs describe the left ventricle blood transit and the kinetic energy and vorticity at the peak of diastolic filling. The PCE-based surrogate models provide straightforward approximations of these QoIs in the space of widely used diagnostic metrics embedding relevant information on left ventricle geometry and function. These surrogates are directly employable in the clinical analysis as we demonstrate by assessing their robustness against independent patient-specific cases ranging from healthy to diseased conditions. The surrogate models are used to perform global sensitivity analysis at a negligible computational cost and provide insights on the impact of each diagnostic metric on the QoIs. Results also suggest how common flow transit parameters are principally dictated by ejection fraction.

Longitudinal CMR assessment of cardiac global longitudinal strain and hemodynamic forces in a mouse model of heart failure

To longitudinally assess left ventricle (LV) global longitudinal strain (GLS) and hemodynamic forces during the early stages of cardiac dysfunction in a mouse model of heart failure with preserved ejection fraction (HFpEF). Cardiac MRI measurements were performed in control mice (n = 6), and db/db mice (n = 7), whereby animals were scanned four times between the age of 11-15 weeks. After the first scan, the db/db animals received a doxycycline intervention to accelerate progression of HFpEF. Systolic function was evaluated based on a series of prospectively ECG-triggered short-axis CINE images acquired from base to apex. Cardiac GLS and hemodynamic forces values were evaluated based on high frame rate retrospectively gated 2-, 3-, and 4-chamber long-axis CINE images. Ejection fraction (EF) was not different between control and db/db animals, despite that cardiac output, as well as end systolic and end diastolic volume were significantly higher in control animals. Whereas GLS parameters were not significantly different between groups, hemodynamic force root mean square (RMS) values, as well as average hemodynamic forces and the ratio between hemodynamic forces in the inferolateral-anteroseptal and apical-basal direction were lower in db/db mice compared to controls. More importantly, hemodynamic forces parameters showed a significant interaction effect between time and group. Our results indicated that hemodynamic forces parameters were the only functional outcome measure that showed distinct temporal differences between groups. As such, changes in hemodynamic forces reflect early alterations in cardiac function which can be of added value in (pre)clinical research on HFpEF.

Introduction to Hemodynamic Forces Analysis: Moving Into the New Frontier of Cardiac Deformation Analysis

The potential relevance of blood flow for describing cardiac function has been known for the past 2 decades, but the association of clinical parameters with the complexity of fluid motion is still not well understood. Hemodynamic force (HDF) analysis represents a promising approach for the study of blood flow within the ventricular chambers through the exploration of intraventricular pressure gradients. Previous experimental studies reported the significance of invasively measured cardiac pressure gradients in patients with heart failure. Subsequently, advances in cardiovascular imaging allowed noninvasive assessment of pressure gradients during progression and resolution of ventricular dysfunction and in the setting of resynchronization therapy. The HDF analysis can amplify mechanical abnormalities, detect them earlier compared with conventional ejection fraction and strain analysis, and possibly predict the development of cardiac remodeling. Alterations in HDFs provide the earliest signs of impaired cardiac physiology and can therefore transform the existing paradigm of cardiac function analysis once implemented in routine clinical care. Until recently, the HDF investigation was possible only with contrast‐enhanced echocardiography and magnetic resonance imaging, precluding its widespread clinical use. A mathematical model, based on the first principle of fluid dynamics and validated using 4‐dimensional‐flow‐magnetic resonance imaging, has allowed HDF analysis through routine transthoracic echocardiography, making it more readily accessible for routine clinical use. This article describes the concept of HDF analysis and reviews the existing evidence supporting its application in several clinical settings. Future studies should address the prognostic importance of HDF assessment in asymptomatic patients and its incorporation into clinical decision pathways.

Reference Ranges of Left Ventricular Hemodynamic Forces in Healthy Adults: A Speckle-Tracking Echocardiographic Study

BACKGROUND

The normal limits of left ventricular (LV) hemodynamic forces (HDFs) are not exactly known. The aim of this study was to explore the full spectrum of HDF parameters in healthy subjects and determine their physiologic correlates.

METHODS

269 healthy subjects were enrolled (mean age: 43 ± 14 years; 123 (45.7%) men). All participants underwent an echo-Doppler examination. Tri-plane tissue tracking from apical views was used to measure 2D global endocardial longitudinal strain (GLS), circumferential strain (GCS), and LV HDFs. HDFs were normalized with LV volume and divided by specific weight.

RESULTS

LV systolic longitudinal HDFs (%) were higher in men (20.8 ± 6.5 vs. 18.9 ± 5.6, p = 0.009; 22.0 ± 6.7 vs. 19.8 ± 5.6, p = 0.004, respectively). There was a significant correlation between GCS (increased) (r = -0.240, p < 0.001) and LV longitudinal HDFs (reduced) (r = -0.155, p = 0.01) with age. In a multivariable analysis age, BSA, pulse pressure, heart rate and GCS were the only independent variables associated with LV HDFs (β coefficient = -0.232, p < 0.001; 0.149, p = 0.003; 0.186, p < 0.001; 0.396, p < 0.001; -0.328, p < 0.001; respectively).

CONCLUSION

We report on the physiologic range of LV HDFs. Knowledge of reference values of HDFs may prompt their implementation into clinical routine and allow a more comprehensive assessment of the LV function.

Sex- and age- specific normal values of left ventricular functional and myocardial mass parameters using threshold-based trabeculae quantification

Background

The threshold-based (TB) trabeculated and papillary muscle mass (TPM) quantification method for cardiac MRI (CMR) calculates different values than conventional contouring techniques. We aimed to identify the sex- and age-related normal reference ranges for left ventricular (LV) myocardial mass values, volumetric and functional parameters and the correspondence of these parameters using the TB method.

Methods

Healthy European adults (n = 200, age: 39.4 ± 12 years, males: 100) were examined with CMR and evaluated with a TB postprocessing method. They were stratified by sex and age (Group A: 18–29, Group B: 30–39, Group C: 40–49, Group D: >50 years). The calculated parameters were indexed to body surface area (i).

Results

The normal reference ranges for the studied parameters were assessed in each age group. Significant biometric differences in LV parameters and mass-to-volume ratios were found between males and females, and the left ventricular compacted myocardial mass (LVCMi) and TPMi differences remained significant after stratification by age. Unlike other LV volumetric and functional parameters and mass-to-volume ratios, the TPMi, the LVCMi and the TPMi-to-LVCMi ratio did not differ among age groups in males or females. This finding was strengthened by the lack of correlation between TPMi and age.

Conclusions

Age- and sex-related normal reference ranges for LV volumetric and functional parameters and LVCMi and TPMi values were established using a TB postprocessing method. TPMi, LVCMi and their ratio did not change over time. The TPMi-to-LVCMi and the mass-to-volume ratios might have clinical utility in the differential diagnosis of conditions with LV hypertrabeculation.

A Novel Approach to Left Ventricular Filling Pressure Assessment: The Role of Hemodynamic Forces Analysis

Background: Diastolic function in patients with heart failure is usually impaired, resulting in increased left ventricular (LV) filling pressures, whose gold standard assessment is right heart catheterization (RHC). Hemodynamic force (HDF) analysis is a novel echocardiographic tool, providing an original approach to cardiac function assessment through the speckle-tracking technology. The aim of our study was to evaluate the use of HDFs, both alone and included in a new predictive model, as a potential novel diagnostic tool of the diastolic function.

Methods: HDF analysis was retrospectively performed in 67 patients enrolled in the “Right1 study.” All patients underwent RHC and echocardiography up to 2 h apart. Increased LV filling pressure (ILFP) was defined as pulmonary capillary wedge pressure (PCWP) ≥ 15 mmHg.

Results: Out of 67 patients, 33 (49.2%) showed ILFP at RHC. Diastolic longitudinal force (DLF), the mean amplitude of longitudinal forces during diastole, was associated with the presence of ILFP (OR = 0.84 [0.70; 0.99], p = 0.046). The PCWP prediction score we built including DLF, ejection fraction, left atrial enlargement, and e' septal showed an AUC of 0.83 [0.76–0.89], with an optimal internal validation. When applied to our population, the score showed a sensitivity of 72.7% and a specificity of 85.3%, which became 66.7 and 94.4%, respectively, when applied to patients classified with “indeterminate diastolic function” according to the current recommendations.

Conclusion: HDF analysis could be an additional useful tool in diastolic function assessment. A scoring system including HDFs might improve echocardiographic accuracy in estimating LV filling pressures. Further carefully designed studies could be useful to clarify the additional value of this new technology.