Search

Background: Left bundle branch block (LBBB) causes left atrial (LA) dyssynchrony. It is unknown if LA dyssynchrony impacts long-term prognosis., Objectives: The purpose of this study was to determine mechanisms of LA dyssynchrony in LBBB and if LA dyssynchrony impacts long-term prognosis., Methods: In a prospective multicenter study of 168 heart failure patients with LBBB, echocardiographic strain imaging was done before and after 6 months with cardiac resynchronization therapy (CRT). Outcome was assessed after 6 years. Dyssynchrony was measured relative to septum as delay in left ventricular (LV) lateral wall shortening and LA lateral wall stretch. Response to CRT was defined as at least 15% reduction in LV end-systolic volume., Results: Before CRT, there was marked LA dyssynchrony of 105 ± 76 ms, which decreased to 37 ± 68 ms in CRT-responders (P < 0.001), whereas nonresponders showed only a modest reduction in LA dyssynchrony (P < 0.05). There was strong association between LA and LV dyssynchrony (r = 0.70), consistent with direct LV-LA mechanical interaction. CRT caused modest increase in LA reservoir strain (P < 0.01) and marked increase of LV filling time (P < 0.001) in responders. Mortality after 6 years was 21% (35 deaths). LA dyssynchrony did not independently predict mortality. However, the combination of preserved LA reservoir strain (≥18%) and resolved LA dyssynchrony (≤53 ms) after 6 months with CRT was associated with excellent long term-prognosis: HR: 0.11 (95% CI: 0.03-0.42) vs preserved reservoir strain and persistent LA dyssynchrony., Conclusions: LA dyssynchrony in LBBB was attributed to direct LV-LA mechanical interactions. CRT improved diastolic function by increasing LV filling time. Patients with preserved LA reservoir strain and resolution of LA dyssynchrony by CRT had excellent long-term prognosis. (Contractile Reserve in Dyssynchrony: A Novel Principle to Identify Candidates for Cardiac Resynchronization Therapy [CRID-CRT]; NCT02525185)., Competing Interests: Funding Support and Author Disclosures Dr Smiseth is co-inventor of “Method for myocardial segment work analysis,” has a patent on “Estimation of blood pressure in the heart” and has received 1 speaker honorarium from GE Healthcare. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Shear wave elastography (SWE) has been proposed as a novel noninvasive method for the assessment of myocardial stiffness, a relevant determinant of diastolic function. It is based on tracking the propagation of shear waves, induced, for instance, by mitral valve closure (MVC), in the myocardium. The speed of propagation is directly related to myocardial stiffness, which is defined by the local slope of the nonlinear stress-strain relation. Therefore, the operating myocardial stiffness can be altered by both changes in loading and myocardial mechanical properties., Objectives: This study sought to evaluate the capability of SWE to quantify myocardial stiffness changes in vivo by varying loading and myocardial tissue properties and to compare SWE against pressure-volume loop analysis, a gold standard reference method., Methods: In 15 pigs, conventional and high-frame rate echocardiographic data sets were acquired simultaneously with pressure-volume loop data after acutely changing preload and afterload and after inducting an ischemia/reperfusion (I/R) injury., Results: Shear wave speed after MVC significantly increased by augmenting preload and afterload (3.2 ± 0.8 m/s vs 4.6 ± 1.2 m/s and 4.6 ± 1.0 m/s, respectively; P = 0.001). Preload reduction had no significant effect on shear wave speed compared to baseline (P = 0.118). I/R injury resulted in significantly higher shear wave speed after MVC (6.1 ± 1.2 m/s; P < 0.001). Shear wave speed after MVC had a strong correlation with the chamber stiffness constant β (r = 0.63; P < 0.001) and operating chamber stiffness dP/dV before induction of an I/R injury (r = 0.78; P < 0.001) and after (r = 0.83; P < 0.001)., Conclusions: Shear wave speed after MVC was influenced by both acute changes in loading and myocardial mechanical properties, reflecting changes in operating myocardial stiffness, and was strongly related to chamber stiffness, invasively derived by pressure-volume loop analysis. SWE provides a novel noninvasive method for the assessment of left ventricular myocardial properties., Competing Interests: Funding Support and Author Disclosures This work is supported by a Research Foundation–Flanders (FWO) project grant (G092318N). Dr Voigt is supported as a senior clinical investigator by the FWO (1832917N). Drs Duchenne and Caenen are supported by an FWO project grant (T002919N and 1211620N). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: The present study investigated the determinants of left atrial (LA) strain in all phases of the cardiac cycle., Background: LA strain by speckle-tracking echocardiography allows the assessment of LA function in each phase of the cardiac cycle. However, its determinants and its relation with left ventricular (LV) function have not yet been fully described., Methods: The authors performed a retrospective analysis in 127 patients with different cardiovascular pathologies. Using 2-dimensional speckle tracking in 4- and 2-chamber apical views we derived both LA and LV strain curves. Strain-strain loops were reconstructed using LV strain and the corresponding, synchronized LA strain data. Linear regressions were calculated for the entire strain-strain loop as well as for the 3 phases of the cardiac cycle (systole, and early and late diastole). The association between LA strain parameters and LV systolic and diastolic parameters was studied. The prediction of cardiovascular events was evaluated for both measured and predicted LA strain and other parameters., Results: LA and LV strain curves presented excellent correlations with an R 2 > 0.90 for the cardiac cycle, and R 2 > 0.97 for its phases. Moreover, the ratios of LV/LA maximal volumes and the slopes of the LA-LV strain-strain loops of the individual patients correlated well (R 2  = 0.75). In each phase of the cardiac cycle, LA strain parameters correlated well with the corresponding LV strain and the LV-LA volume ratio (R 2 > 0.78). No significant difference in predictive ability of cardiovascular events or atrial fibrillation between the measured and predicted LA strain was observed (P > 0.05 for both)., Conclusions: In the absence of abnormal LA/LV volume exchange, LA strain is, to a large extent, determined by LV strain and further modulated by the ratio of LV and LA volumes. Nonetheless, measuring LA strain is of high clinical interest because it integrates several parameters into a single, robust, and reproducible measurement., Competing Interests: Funding Support and Author Disclosures Dr Petrescu was supported by a research grant from the German Society of Cardiology (Deutsche Gesellschaft für Kardiologie). Dr Duchenne is supported by a project grant from the Research Foundation Flanders (Fonds Wetenschappalijk Onderzoek Flanderen [FWO]). Prof Dr Voigt holds a personal research mandate of the FWO. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022. Published by Elsevier Inc.)

Objectives: This study sought to investigate if contractile asymmetry between septum and left ventricular (LV) lateral wall drives heart failure development in patients with left bundle branch block (LBBB) and whether the presence of lateral wall dysfunction affects potential for recovery of LV function with cardiac resynchronization therapy (CRT)., Background: LBBB may induce or aggravate heart failure. Understanding the underlying mechanisms is important to optimize timing of CRT., Methods: In 76 nonischemic patients with LBBB and 11 controls, we measured strain using speckle-tracking echocardiography and regional work using pressure-strain analysis. Patients with LBBB were stratified according to LV ejection fraction (EF) ≥50% (EF preserved ), 36% to 49% (EF mid ), and ≤35% (EF low ). Sixty-four patients underwent CRT and were re-examined after 6 months., Results: Septal work was successively reduced from controls, through EF preserved , EF mid , and EF low (all p < 0.005), and showed a strong correlation to left ventricular ejection fraction (LVEF; r = 0.84; p < 0.005). In contrast, LV lateral wall work was numerically increased in EF preserved and EF mid versus controls, and did not significantly correlate with LVEF in these groups. In EF low, however, LV lateral wall work was substantially reduced (p < 0.005). There was a moderate overall correlation between LV lateral wall work and LVEF (r = 0.58; p < 0.005). In CRT recipients, LVEF was normalized (≥50%) in 54% of patients with preserved LV lateral wall work, but only in 13% of patients with reduced LV lateral wall work (p < 0.005)., Conclusions: In early stages, LBBB-induced heart failure is associated with impaired septal function but preserved lateral wall function. The advent of LV lateral wall dysfunction may be an optimal time-point for CRT., Competing Interests: Funding Support and Author Disclosures Drs Sletten and Aalen were supported by grants from the Norwegian Health Association. Dr Larsen was a recipient of a clinical research fellowships form the South-Eastern Norway Regional Health Authority. Prof Voigt holds a personal research mandate of the Flemish Research Council. Prof Voigt and Dr Duchenne were further supported by a grant of the University of Leuven. Dr Smiseth is co-inventor, but since May 24, 2017 has had no financial relations to the patent “Method for myocardial segment work analysis,” which was used to calculate the myocardial work. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose, (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to investigate whether propagation velocities of naturally occurring shear waves (SWs) at mitral valve closure (MVC) increase with the degree of diffuse myocardial injury (DMI) and with invasively determined LV filling pressures as a reflection of an increase in myocardial stiffness in heart transplantation (HTx) recipients., Background: After orthotopic HTx, allografts undergo DMI that contributes to functional impairment, especially to increased passive myocardial stiffness, which is an important pathophysiological determinant of left ventricular (LV) diastolic dysfunction. Echocardiographic SW elastography is an emerging approach for measuring myocardial stiffness in vivo. Natural SWs occur after mechanical excitation of the myocardium, for example, after MVC, and their propagation velocity is directly related to myocardial stiffness, thus providing an opportunity to assess myocardial stiffness at end-diastole., Methods: A total of 52 HTx recipients who underwent right heart catheterization (all) and cardiac magnetic resonance (CMR) (n = 23) during their annual check-up were prospectively enrolled. Echocardiographic SW elastography was performed in parasternal long axis views of the LV using an experimental scanner at 1,135 ± 270 frames per second. The degree of DMI was quantified with T1 mapping., Results: SW velocity at MVC correlated best with native myocardial T1 values (r = 0.75; p < 0.0001) and was the best noninvasive parameter that correlated with pulmonary capillary wedge pressures (PCWP) (r = 0.54; p < 0.001). Standard echocardiographic parameters of LV diastolic function correlated poorly with both native T1 and PCWP values., Conclusions: End-diastolic SW propagation velocities, as measure of myocardial stiffness, showed a good correlation with CMR-defined diffuse myocardial injury and with invasively determined LV filling pressures in patients with HTx. Thus, these findings suggest that SW elastography has the potential to become a valuable noninvasive method for the assessment of diastolic myocardial properties in HTx recipients., Competing Interests: Author Relationship With Industry This work was supported by the European Research Council (FP7/2007-2013, ERC/281748) and the Research Foundation- Flanders (FWO/G002617N, FWO/G092318N). Dr. Petrescu was supported by a German Society of Cardiology Research Grant and Marta Cvijic by a European Association of Cardiovascular Imaging Research Grant. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to investigate how LBBB and CRT modify RV free wall function by direct ventricular interaction., Background: Right ventricular (RV) function influences prognosis in patients with left bundle branch block (LBBB) and cardiac resynchronization therapy (CRT). There is, however, limited insight into how LBBB and CRT affect RV function., Methods: In 24 patients with LBBB with nonischemic cardiomyopathy, RV and left ventricular (LV) strain by speckle-tracking echocardiography was measured before and after CRT. Underlying mechanisms were studied in 16 anesthetized dogs with ultrasonic dimension crystals and micromanometers., Results: Patients with LBBB demonstrated distinct early systolic shortening in the RV free wall, which coincided with the typical abnormal early systolic septal shortening. In animals, this RV free wall contraction pattern resulted in reduced myocardial work as a large portion of the shortening occurred against low pressure during early systole, coinciding with abnormal leftward septal motion. RV systolic function was maintained by vigorous contraction in the late-activated LV lateral wall, which pushed the septum toward the RV. CRT reduced abnormal septal motion and increased RV free wall work because there was less inefficient shortening against low pressure., Conclusions: LBBB reduces workload on the RV free wall because of abnormal septal motion and delayed activation of the LV lateral wall. Restoring septal and LV function by CRT increases workload in RV free wall and may explain why patients with RV failure respond poorly to CRT. (Contractile Reserve in Dyssynchrony: A Novel Principle to Identify Candidates for Cardiac Resynchronization Therapy [CRID-CRT]; NCT02525185)., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to investigate how regional left ventricular (LV) function modifies septal motion in left bundle branch block (LBBB)., Background: In LBBB, the interventricular septum often has marked pre-ejection shortening, followed by immediate relengthening (rebound stretch). This motion, often referred to as septal flash, is associated with positive response to cardiac resynchronization therapy (CRT)., Methods: In 10 anesthetized dogs, we induced LBBB by radiofrequency ablation and occluded the circumflex (CX) (n = 10) and left anterior descending (LAD) (n = 6) coronary arteries, respectively. Myocardial dimensions were measured by sonomicrometry and myocardial work by pressure-segment length analysis. In 40 heart failure patients with LBBB, including 20 with post-infarct scar and 20 with nonischemic cardiomyopathy, myocardial strain was measured by speckle-tracking echocardiography and myocardial work by pressure-strain analysis. Scar was assessed by cardiac magnetic resonance imaging with late gadolinium enhancement., Results: During LBBB, each animal showed typical septal flash with pre-ejection shortening and rebound stretch, followed by reduced septal systolic shortening (p < 0.01). CX occlusion caused LV lateral wall dysfunction and abolished septal flash due to loss of rebound stretch (p < 0.0001). Furthermore, CX occlusion restored septal systolic shortening to a similar level as before induction of LBBB and substantially improved septal work (p < 0.001). LAD occlusion, however, accentuated septal flash by increasing rebound stretch (p < 0.05). Consistent with the experimental findings, septal flash was absent in patients with LV lateral wall scar due to lack of rebound stretch (p < 0.001), and septal systolic shortening and septal work far exceeded values in nonischemic cardiomyopathy (p < 0.0001). Septal flash was present in most patients with anteroseptal scar., Conclusions: LV lateral wall dysfunction and scar abolished septal flash and markedly improved septal function in LBBB. Therefore, function and scar in the LV lateral wall should be taken into account when septal motion is used to evaluate dyssynchrony., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: This study aimed to investigate to what extent timing definitions influence strain measurements and which surrogates are reliable and feasible to define end-diastole (ED) and end-systole (ES) during speckle-tracking (STI) analysis., Background: Current STI-based strain measurements are highly automated. It remains unclear when a particular analysis software defines the zero baseline and the systolic strain measurement position., Methods: A total of 60 subjects (20 healthy volunteers, 20 patients with coronary artery disease, and 20 patients with typical left bundle-branch block) underwent a complete echocardiographic examination. In one-half of them, a real M-mode through the mitral valve was acquired for each electrocardiographic (ECG) lead of the echo machine. Timing of peak R and automatic ECG trigger were compared with mitral valve closure for every electrode. Mitral and aortic valve closure, as observed in the apical 3-chamber view, served as reference for ED and ES. With the use of these references, end-systolic global longitudinal strain (ES-GLS) and end-systolic segmental longitudinal strain (ES-SLS) longitudinal end-systolic strain were measured at baseline and after changing the definition of either ED or ES by ±4 frames. Furthermore, strain and volume curves derived from the same tracking, as well as the Doppler interrogation of the valves, were compared with the references., Results: Depending on the selected lead, timing of the ECG-derived time markers changed considerably compared with mitral valve closure. Changing the definition of ED and ES resulted in significantly different ES-GLS and ES-SLS values in all subjects. ES-SLS in dyssynchronous hearts showed the highest sensitivity to timing definition. From all methods, spectral Doppler was the most reliable time marker in all subjects (p > 0.05)., Conclusions: Exact temporal definition of ED and ES has a major impact on the accuracy of strain measurements. After direct observation of the valves, Doppler evaluation is the best means for characterizing ED and ES for STI analysis., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)