Left Ventricular Mechanical Function Research Articles

Optimizing Resuscitation of the Donation after Circulatory Death Heart by Mitochondrial Protection in a Female Porcine Model.

Due to the shortage of donor organs, an increasing number of transplant organs are harvested after circulatory arrest (donation after circulatory death [DCD]). Using a translational porcine model of DCD, this study developed and evaluated a protocol based on cardioprotection by multidrug postconditioning to optimize resuscitation of DCD hearts during ex situ heart perfusion (ESHP). Hearts of female pigs (45.0 ± 4.5 kg) were procured following a clinically identical DCD protocol, consisting of the termination of ventilator support and confirmation of circulatory arrest, followed by a 15-min standoff period. DCD hearts were randomly allocated to ESHP (38.4°C) in the absence (untreated, N = 5) or presence (treated, N = 5) of a postconditioning treatment added to the perfusate, consisting of Intralipid (1%), sevoflurane (2% v/v), and remifentanil (3 nM). All hearts were perfused with blood and Krebs-Henseleit solution (1:1) for 60 min in Langendorff mode and for an additional 300 min in working mode for a total perfusion time of 6 h. Oxidative capacity and detailed left ventricular mechanical function under an increasing workload (left atrial pressure, 6 to 12 mmHg) were assessed hourly. Left ventricular tissue was snap-frozen at the end of ESHP and used for molecular analyses. Left ventricular inotropy (LVdP/dtmax) did not decline over time in treated DCD hearts and was significantly higher at the end of the protocol as compared with untreated DCD hearts (ΔLVdP/dtmax = 440 mmHg/s; P = 0.009). Treated DCD hearts exhibited persistently higher left ventricular stroke work index during the 6-h period of ESHP, whereas untreated DCD hearts displayed a significant decline (change in left ventricular stroke work index = -3.10 ml · mmHg/g; P(time within untreated group) < 0.001). Treated DCD hearts displayed higher metabolic activity as measured by oxygen consumption (ΔO2 = 3.11 ml O2 · min-1 · 100 g-1; P = 0.004) and released lower amounts of cell-free mitochondrial DNA into the perfusate, a marker of potential graft dysfunction. Treated hearts also used fatty acids from Intralipid as an energy source, whereas untreated DCD hearts showed glyceroneogenesis with triglyceride accumulation and depletion of tricarboxylic acid cycle intermediates; reduced mitochondrial complex I, II, and III activities with accumulation of mitochondrial NADH, and signs of ultrastructural damage. A translationally relevant protective ESHP protocol consisting of treatment with Intralipid, sevoflurane, and remifentanil markedly accelerated functional recovery and improved viability of DCD hearts.

Prognostic Implications of Left Ventricular Hypertrophy and Mechanical Function in Fabry Disease: A Longitudinal Cohort Study

The prognostic value of different grades of left ventricular hypertrophy (LVH) and left ventricular (LV) mechanical function in Fabry disease is unclear. We aimed to evaluate the association between the severity of LVH, LV mechanical function, and clinical outcomes in Fabry disease. We conducted a retrospective cohort study from a single-center registry of adult patients with Fabry disease. Left ventricular mass index (LVMI) was measured by echocardiography. The severity of LVH was categorized by LVMI using the sex-specific cutoff values. Left ventricular mechanical function was measured as LV global longitudinal strain (GLS) by speckle-tracking analysis. The primary outcome was a composite of major adverse cardiovascular events (MACE) at 5years, including heart failure hospitalization, sustained ventricular tachycardia, acute ischemic stroke, and all-cause mortality. The study included 268 patients (age 50.4±15.4years, men 46.6%) with Fabry disease (83.2% IVS4+919G>A mutation), and 106 patients (39.6%) had LVH. Patients with mild, moderate, or severe LVH had 5-year MACE rates of 7.4%, 10%, and 30.5%, respectively (P<.001). Moreover, patients with impaired LV GLS (<14.1%) had a higher 5-year MACE rate than those with preserved LV GLS (32.1% vs 2.4%, P<.001). Severe LVH was an independent predictor of MACE compared with absence of LVH (adjusted hazard ratio, 12.73; 95% CI, 1.3-124.71; P=.03), after adjusting for age, sex, hypertension, hyperlipidemia, atrial fibrillation, renal function, average E/e', enzyme replacement therapy, and LV GLS. Patients with severe LVH and impaired LV GLS had the highest incidence for MACE (log-rank P<.05), irrespective of sex, genotypes, and whether receiving enzyme replacement therapy or not. Sex-specific grading of LVH by LVMI is practical for risk stratification in patients with Fabry disease, and impaired LV GLS further refines the prognostication.

Left bundle branch pacing better preserves ventricular mechanical synchrony than right ventricular pacing: a two-centre study.

Left bundle branch pacing (LBBP) has been shown to better maintain electrical synchrony compared with right ventricular pacing (RVP), but little is known about its impact on mechanical synchrony. This study investigates whether LBBP better preserves left ventricular (LV) mechanical synchronicity and function compared with RVP. Sixty patients with pacing indication for bradycardia were included: LBBP (n = 31) and RVP (n = 29). Echocardiography was performed before and shortly after pacemaker implantation and at 1-year follow-up. The lateral wall-septal wall (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking, and septal strain patterns were also assessed. At baseline, LW-SW work difference was small and similar in two groups. SW was markedly decreased, while LW work remained mostly unchanged in RVP, resulting in a larger LW-SW work difference compared with LBBP (1253 ± 687 mmHg·% vs. 439 ± 408 mmHg·%, P < 0.01) at last follow-up. In addition, RVP more often induced septal flash or apical rocking and resulted in more advanced strain patterns compared with LBBP. At 1 year follow-up, LV ejection fraction (EF) and global longitudinal strain (GLS) were more decreased in RVP compared with LBBP (ΔLVEF: -7.4 ± 7.0% vs. 0.3 ± 4.1%; ΔLVGLS: -4.8 ± 4.0% vs. -1.4 ± 2.5%, both P < 0.01). In addition, ΔLW-SW work difference was independently correlated with LV adverse remodelling (r = 0.42, P < 0.01) and LV dysfunction (ΔLVEF: r = -0.61, P < 0.01 and ΔLVGLS: r = -0.38, P = 0.02). LBBP causes less LV mechanical dyssynchrony than RVP as it preserves a more physiologic electrical conduction. As a consequence, LBBP appears to preserve LV function better than RVP.

Quinapril treatment curtails decline of global longitudinal strain and mechanical function in hypertensive rats.

Left ventricular (LV) global longitudinal strain (GLS) has been proposed as an early imaging biomarker of cardiac mechanical dysfunction. To assess the impact of angiotensin-converting enzyme (ACE) inhibitor treatment of hypertensive heart disease on LV GLS and mechanical function. The spontaneously hypertensive rat (SHR) model of hypertensive heart disease (n = 38) was studied. A subset of SHRs received quinapril (TSHR, n = 16) from 3 months (mo). Wistar Kyoto rats (WKY, n = 13) were used as controls. Tagged cardiac MRI was performed using a 4.7 T Varian preclinical scanner. The SHRs had significantly lower LV ejection fraction (EF) than the WKYs at 3 mo (53.0 ± 1.7% vs. 69.6 ± 2.1%, P < 0.05), 14 mo (57.0 ± 2.5% vs. 74.4 ± 2.9%, P < 0.05) and 24 mo (50.1 ± 2.4% vs. 67.0 ± 2.0%, P < 0.01). At 24 mo, ACE inhibitor treatment was associated with significantly greater LV EF in TSHRs compared to untreated SHRs (64.2 ± 3.4% vs. 50.1 ± 2.4%, P < 0.01). Peak GLS magnitude was significantly lower in SHRs hearts compared with WKYs at 14 months (7.5% ± 0.4% vs. 9.9 ± 0.8%, P < 0.05). At 24 months, Peak GLS magnitude was significantly lower in SHRs compared with both WKYs (6.5 ± 0.4% vs. 9.7 ± 1.0%, P < 0.01) and TSHRs (6.5 ± 0.4% vs. 9.6 ± 0.6%, P < 0.05). ACE inhibitor treatment curtails the decline in global longitudinal strain in hypertensive rats, with the treatment group exhibiting significantly greater LV EF and GLS magnitude at 24 mo compared with untreated SHRs.

Vagal Nerve Stimulation Reduces Ventricular Arrhythmias and Mitigates Adverse Neural Cardiac Remodeling Post–Myocardial Infarction

This study sought to evaluate the impact of chronic vagal nerve stimulation (cVNS) on cardiac and extracardiac neural structure/function after myocardial infarction (MI). Groups were control, MI, and MI+ cVNS; cVNS was started 2days post-MI. Terminal experiments were performed 6weeks post-MI. MI impaired left ventricular mechanical function, evoked anisotropic electrical conduction, increased susceptibility to ventricular tachycardia and fibrillation, and altered neuronal and glial phenotypes in the stellate and dorsal root ganglia, including glial activation. cVNS improved cardiac mechanical function and reduced ventricular tachycardia/ventricular fibrillation post-MI, partly by stabilizing activation/repolarization in the border zone. MI-associated extracardiac neural remodeling, particularly glial activation, was mitigated with cVNS.

Abstract 9808: Deletion of Arrdc4 Enhances Myocardial Glucose Transport and Ameliorates Ischemic Injury

Cardiomyocytes depend on glycolysis instead of oxidative phosphorylation during hypoxia and utilize glucose as a primary anaerobic energy source. Cardiac glucose transport is facilitated by the expression of glucose transporters (GLUT1 and GLUT4) on the cell surface. The arrestins are a family of proteins that regulate the signaling and trafficking of different receptors and transporters on the plasma membrane. As a scaffold protein, beta-arrestins mediate endocytosis and signal termination of beta-adrenergic receptors in cardiomyocytes. However, unlike the well-characterized beta-arrestins, the physiological roles of the related proteins termed alpha-arrestins remain largely unknown in the heart. In this study, we discovered for the first time that a member of alpha-arrestins, Arrestin Domain-Containing Protein 4 (Arrdc4), functions as a regulatory scaffold protein of GLUT1 and controls cardiac glucose metabolism. We found that Arrdc4 interacts with GLUT1 and promotes its endocytosis in cardiomyocytes. Interestingly, the cardiac expression of Arrdc4 is significantly upregulated by myocardial ischemia. Arrdc4 decreases cell surface expression of GLUT1 and suppresses glucose transport in the wild-type (WT) mouse heart. Then, we generated a novel Arrdc4 knockout (KO) mouse using CRISPR/Cas9 genome editing and characterized the effects of Arrdc4 in an animal model of myocardial infarction (MI) by coronary artery ligation in vivo. Surprisingly, Arrdc4-KO mice exhibit smaller infarct size, fewer apoptotic cells, and higher left ventricular (LV) fractional shortening, resulting in better post-MI survival than WT mice. Furthermore, using the Langendorff perfusion system, we found that Arrdc4-KO hearts augment cardiac glucose transport and preserve better LV mechanical function during anaerobic perfusion than WT hearts ex vivo. These results demonstrate that Arrdc4-KO cardiomyocytes coordinately maintain the optimal expression of GLUT1 on the cell surface, which leads to a metabolic rearrangement to secure energy homeostasis under oxygen- and nutrient-limited environments. In conclusion, we identified Arrdc4 as a new adaptor protein for GLUT1 in cardiomyocytes and a key player in cardiac metabolism in the ischemic heart.

Abstract 12901: Cardiac Reverse Remodeling and Functional Changes Assessed by Speckle Tracking Echocardiography After Septal Myectomy in Patients With Symptomatic Hypertrophic Obstructive Cardiomyopathy

Introduction &amp; Hypothesis: Surgical septal myectomy is an effective treatment in patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM). Reducing the hemodynamic burden through septal myectomy in HOCM patients is expected to result in cardiac reverse remodeling, but it is unknown whether it improves myocardium functional parameters, which are proven prognosticators for clinical outcome. Therefore, this study aimed to investigate the left atrial (LA) and left ventricular (LV) size and function using conventional and speckle tracking echocardiography (STE) before and after septal myectomy in patients with HOCM. Methods: A total of 65 patients with symptomatic HOCM who underwent surgical septal myectomy from 2006 to 2021 were retrospectively analyzed. Patients were excluded if they underwent a valve repair or replacement at the same time. Finally, clinical, echocardiographic, and electrocardiographic variables before and after the surgery were comprehensively analyzed. Results: After septal myectomy, there were significant decreases in LA volume index (72±22 vs. 57±18 ml/m 2 , p &lt;0.001) suggestive of improvement of diastolic function. In the analysis of STE, there was no significant difference in LA strain (19.3±8.5 vs. 19.1±8.2%, p=0.883) and LV global longitudinal strain (LS) (-10.3±3.6 vs. -9.6±3.4%, p=0.150) before and after septal myectomy. When we analyzed LV regional LS by dividing into septum and non-septum, septal LS showed a little aggravation (-8.7±4.5 vs. -7.6±3.7 %, p=0.077) with marginal statistical significance. In addition, non-septal LS was not significantly different after septal myectomy (-10.9±4.5 vs. -10.5 ±4.2 %, p= 0.458). The change of LA volume index was significantly correlated with change of QRS duration. Interestingly, the septal LS was deteriorated and non-septal LS tended to be improved as widening of QRS duration. Conclusions: After septal myectomy, as hemodynamic load due to LVOT obstruction relieves, there is a significant reduction in LA volume. However, there is no improvement in the global LA and LV mechanical function. Widening of QRS duration, a marker of effective septal myectomy, is associated with LA volume reduction and improvement of longitudinal strain in non-septal LV.

Clinical research progress of myocardial work in assessment and prediction of coronary artery disease in noninvasive pressure-strain loop technique.

Early identification and treatment of high-risk coronary artery disease (CAD) is the main goal of current cardiovascular disease treatments. Speckle-tracking ultrasound technology can quantify myocardial work using pressure-strain loops. Because myocardial work takes into account the effect of the left ventricular systolic function afterload, it can more objectively reflect left ventricular myocardial mechanical function than the overall left ventricular longitudinal strain. Therefore, this technique is more widely used in diseases caused by CAD. This article reviews the evaluation and prediction of different CAD types using a variety of myocardial work parameters and provides a new method for clinical research to assess myocardial function, which is expected to become a new prediction method for CAD.

Left Ventricular Global Longitudinal Strain Is Associated With Cardiovascular Outcomes in Patients Who Underwent Permanent Pacemaker Implantation.

Background: Patients who underwent permanent pacemaker (PM) implantation have a potential risk of left ventricular (LV) systolic dysfunction. However, assessment of LV ejection fraction (LVEF) shows a limited role in identifying subclinical LV systolic dysfunction and predicting cardiovascular (CV) outcomes.Methods: We reviewed 1,103 patients who underwent permanent PM implantation between January 2007 and December 2017. After excluding patients who did not undergo echocardiograms before or after PM implantation and those with LV ejection fraction (LVEF) <50%, significant valve dysfunction, and history of cardiac surgery before PM implantation, 300 (67 ± 13 years, 119 men) were finally analyzed. LV mechanical function was assessed with LV global longitudinal strain (LV-GLS) using 2-dimensional speckle-tracking echocardiography. CV outcomes were defined as a composite of CV death and hospitalization for heart failure.Results: At 44 ± 28 months after post-PM echocardiogram, 23 patients (7.7%) had experienced CV outcomes. Patients with CV outcomes were older and had more comorbidities and a lower baseline |LV-GLS| than those without CV outcomes. LV mechanical function worsened after PM implantation in patients with CV outcomes. The cut-off value of 11.2% in |LV-GLS| on post-PM echocardiogram had a better predictive value for CV outcomes (AUC; 0.784 vs. 0.647, p = 0.012). CV outcome in patients with |LV-GLS| <11.2% was worse than that in those with |LV-GLS| ≥ 11.2% (log-rank p < 0.001). Multivariate Cox model revealed that reduced |LV-GLS| was independently associated with CV outcomes.Conclusions: Pacing deteriorates LV mechanical function. Impaired LV-GLS is associated with poor CV outcomes in patients who underwent PM implantation.

The effect of external counterpulsation on intrinsic myocardial function evaluated by speckle tracking echocardiography in refractory angina patients: a randomized controlled trial.

External Counterpulsation (ECP) is one of the therapeutic options in patients with refractory angina inadequately controlled by medical, interventional, or surgical therapy. The 2D Speckle Tracking Echocardiography (2D-STE) method is considered superior in assessing clinical improvement. We would like to evaluate any improvement ofmyocardial intrinsic function using 2D-STE in patients underwent standard ECP protocol (35 sessions). We conducted a double-blind randomized controlled trial. Patients with refractory angina who could not be revascularized conventionally were randomized into two groups: (1) the ECP group (300mmHg) and (2) the Sham/control group (75mmHg). ECP standard therapy was given for 35 sessions (1h/day/session). The 2D-STE data, including longitudinal strain and post systolic index (PSI) were obtained before and after therapy. 43 subjects were analyzed, with 22 subjects in ECP group and 21 control subjects (Sham group). A homogenous baseline strain was found either globally (12.42 ± 4.55 vs 12.00 ± 4.92 [-%]; P = 0.774) or segmentally/regionally (12.63 (0.01-25.16) vs 12.43 (0.01-27.20) [-%]; P = 0.570). There was no statistically significant improvement between groups in the left ventricle longitudinal strain globally (P = 0.535) and segmentally/regionally (P = 0.434). PSI parameters showed improvement in the ECP group (P = 0.049), and segments with PSI ≥ 20% seemed to improve longitudinal strains in the ECP group after therapy (P = 0.042). In conclusion, 35 ECP therapy sessions did not improve either global or segmental/regional left ventricular mechanical function in patients with refractory angina.However, the mechanical function of myocardial segments with PSS tends to improve after ECP therapy.

Abstract 14245: Fibroblast Growth Factor 23 and Long-term Cardiac Function: The Multi- Ethnic Study of Atherosclerosis

Background: While fibroblast growth factor 23 (FGF23) is associated with incident heart failure (HF) and atrial fibrillation (AF), the mechanisms driving these associations are unclear. FGF23 elevation leads to cardiomyocyte calcium handling abnormalities, suggesting that FGF23 may directly reduce myocardial function. Methods: In the Multi-Ethnic Study of Atherosclerosis, a cohort free of cardiovascular disease at recruitment, we evaluated the associations of serum FGF23 (2000-2002) with measures of left ventricular (LV) and left atrial (LA) mechanical function on cardiac magnetic resonance (CMR) at 10-year follow up (2010-2012). Results: Of 2,276 participants with baseline FGF23 and CMR at 10-year follow up, participants with higher FGF23 levels were more likely white race, taking anti-hypertensive medications, and had lower baseline glomerular filtration rate (GFR). After covariate adjustment, baseline FGF23 levels were independently associated with worse LV global circumferential strain, worse LV mid-wall circumferential strain, and lower LA total emptying fraction in later life ( Table ). The association of FGF23 and LV global circumferential strain was consistent across the spectrum of GFR ( Figure ). While higher FGF23 was associated with higher LV mass (β coefficient per SD higher: 1.14, 95% CI: 0.16, 2.12, P= 0.02), it was not associated with the presence of macroscopic myocardial scar (OR per SD higher: 1.12, 95% CI: 0.86-1.45, P= 0.42). Conclusions: Baseline FGF23 is independently associated with lower LV and LA systolic function in later life. These findings provide mechanistic insight driving the associations of FGF23 with development of both HF and AF.

Abstract 13078: Evaluation of Ventricular Function in Fetus With Transposition of Great Arteries by Velocity Vector Imaging

Background: The aim of this study was to test the hypotheses that (1) fetuses with complete transposition of the great arteries (D-TGA) and Taussig-Bing anomaly (TBA) has decreased the left ventricular (LV) and right ventricular(RV) mechanical function compared with normal fetuses, and (2)the decreased myocardial mechanical function in fetal D-TGA and TBA was associated with the degree of transposition of the great arteries, pulmonary stenosis(PS) and ventricular septal defect(VSD). Methods: We retrospectively identified 49 cases of fetal D-TGA and 29 cases of fetal TBA and compared findings to 49 controls of comparable gestational age. Postprocessing analysis of the left ventricle and right ventricle were done using syngo Velocity Vector Imaging version 2.3. Global and regional longitudinal systolic peak velocity, strain and strain rate were generated. Results: (1) Comparing with control group, the global and regional longitudinal systolic peak velocity (GLV), strain (GLS) and strain rate (GLSR) of the LV and RV were decreased in the group of D-TGA and TBA (P&lt;0.05). (2) In the group of D-TGA and TBA, the multivariate linear regression analysis, the VSD was the independent determinant of LVGLS and RVGLS (β = 0.270, P=0.014 and β = 0.465, P&lt; 0.001). The PS was the independent determinant of RVGLSR (β = 0.090, P=0.009). Conclusion: The ventricular function of fetal D-TGA and TBA were decreased compared with control group. The PS and VSD were the independent determinant factors of the decreased LVGLS, RVGLS and RVGLSR in the fetal D-TGA and TBA.

Fibroblast Growth Factor 23 and Long-Term Cardiac Function: The Multi-Ethnic Study of Atherosclerosis.

Although FGF23 (fibroblast growth factor 23) is associated with heart failure and atrial fibrillation, the mechanisms driving these associations are unclear. Sensitive measures of cardiovascular structure and function may provide mechanistic insight behind the associations of FGF23 with various cardiovascular diseases. In MESA (the Multi-Ethnic Study of Atherosclerosis), we evaluated the associations of baseline serum FGF23 (2000-2002) with measures of left ventricular (LV) and left atrial mechanical function on cardiac magnetic resonance at 10-year follow-up (2010-2012). Of 2276 participants with available FGF23 and cardiac magnetic resonance at 10-year follow-up, participants with higher FGF23 levels were more likely White race, taking antihypertensive medications, and had lower kidney function. After covariate adjustment, FGF23 was associated with higher LV mass (β coefficient per 1 SD higher, 1.14 [95% CI, 0.16-2.12], P=0.02), worse LV global circumferential strain (β coefficient per 1 SD higher, 0.15 [95% CI, 0.05-0.25], P=0.003), worse LV midwall circumferential strain (β coefficient per 1 SD higher, 0.20 [95% CI, 0.08-0.31], P=0.001), and lower left atrial total emptying fraction (β coefficient per 1 SD higher, -0.52 [95% CI, -1.02 to -0.02], P=0.04). These associations were consistent across racial/ethnic groups and the spectrum of glomerular filtration rates. FGF23 was not associated with the presence of myocardial scar (odds ratio per 1 SD higher, 1.12 [95% CI, 0.86-1.45], P=0.42). In a multiethnic, community-based cohort, baseline FGF23 levels were independently associated with higher LV mass, lower LV systolic function, and reduced left atrial function over long-term follow-up. These findings provide potential mechanistic insight into associations of FGF23 with incident heart failure and atrial fibrillation.

Early change in left atrial and left ventricular strain predicts sinus rhythm maintenance after cardioversion

Abstract Background Atrial fibrillation (AF) impairs mechanical function of the heart, especially atria and restoration of sinus rhythm (SR) leads to improvement of mechanics. The predicting role of changes in strain parameters for AF recurrence is not established yet. Purpose To analyse changes in left atrial (LA) and left ventricular (LV) mechanical function after conversion to SR and their prognostic values for AF recurrence during 24 months follow-up. Methods Prospective study involved 59 patients after successful electrical cardioversion (EC) because of nonvalvular AF (mean age 65±4 years, 47% female). Speckle tracking analysis (STE) was applied to calculate longitudinal strain of LV and LA before EC and within 24 hours after restoration of SR and additionally total left heart strain (TS) defined as a sum of absolute peak LV and LA strain. We calculated change in strain between AF and SR analyses expressed as delta (Δ). During follow-up we noticed AF recurrence in 42 (71%) patients, most of them (93%) during 1st year after EC. Median time of AF recurrence was 3 months. Results We noticed significant immediate post-EC improvement in peak LA longitudinal strain (PALS) and LV global longitudinal strain (LVGLS) (table). Unlike CHA2DS2-VASc score, strain parameters were predictors of AF recurrence. Every 1% increment in ΔLVGLS was related with 13% increase in AF recurrence risk (p=0.02) and every 1% increment in ΔPALS and ΔTS were related with 9% decrease in AF recurrence risk (p=0.007 and p=0.0014, respectively). Multivariate analysis revealed ΔTS as a strongest predictor with 9% decrease in AF risk per every 1% increment. The criterion of ΔTS ≤7.5% allows to predict AF recurrence with 81% sensitivity and 63% specificity. Conclusions Speckle tracking measurements are able to detect early mechanical changes in LA even within 24 hours of SR and these absolute changes in LVGLS as well as PALS can predict AF recurrence, with optimal stratification by novel parameter - TS. Funding Acknowledgement Type of funding source: None

Left Heart Dysfunction in Acromegaly Revealed by Novel Echocardiographic Methods.

Background: Acromegaly is a rare disease that requires modern treatment to decrease the risk of mortality, mainly from vascular diseases. Identifying acromegalic patients with increased cardiovascular risk is challenging. Speckle-tracking echocardiography (STE) is a modern, well-validated, and reproducible method of assessing left ventricular longitudinal deformation and providing a sensitive assessment of myocardial contractility. We hypothesized that STE may be useful in evaluating subclinical dysfunction of the left heart in acromegalic patients, especially when a left ventricle (LV) assessment is completed with STE of the left atrium (LA).Purpose: To assess the diagnostic value of speckle-tracking echocardiography in identifying the occurrence of LV and LA functional impairment in patients with acromegaly, in comparison to patients without this rare pituitary disease.Methods: Echocardiographic assessments of LV and LA function using the new STE method were performed in 60 subjects: 30 acromegalic (ACRO group) patients and a CONTROL group with 30 patients matched in terms of age, gender, systolic/diastolic pressure, and history of hypertension for at least 12 months.Results: The ACRO group, compared to the CONTROL group, presented: (1) higher left ventricular mass (left ventricular mass index: 132 vs. 108 g/m2, p < 0.001) and, in consequence, more frequent LV hypertrophy (80.0 vs. 53.3%; p = 0.028); (2) impaired LV systolic function measured by both left ventricular ejection fraction (LVEF) (63.4 vs. 66.9%, p < 0.001) and global longitudinal strain (GLS) (−18.1 vs. −19.4%, p = 0.023); (3) greater LA anteroposterior diameter (40.3 vs. 36.9 mm, p = 0.003) and indexed left atrial volume (37.9 vs. 27.6 ml/m2, p < 0.001); and (4) impaired echocardiographic strain parameters corresponding with LA function.Conclusions: Acromegaly, even in young patients with good blood pressure control, may be associated with left ventricular hypertrophy and subclinical impairment of the left ventricular and left atrial mechanical function, which may be identified by speckle-tracking echocardiography. Further research in this area is necessary to clarify the prognostic value of these phenomena.

Assessment of Left Ventricular Asynchrony after Permanent Cardiac Pacing by Using Speckle Tracking Echocardiography

AbstractBackground: Echocardiography is important in assessing Left Ventricular (LV) Mechanical Dysynchrony (LVMD) and left ventricular function after permanent pacemaker. At present, Real-Time Three Dimensional Echocardiography (RT3DE) and tissue Doppler imaging (TDI) are the most sensitive and commonly used techniques for the quantification of LVMD. Global longitudinal strain (GLS) and LV dyssynchrony as-sessment enables us to detect early signs of LV dysfunction after cardiac pacing.Aim of Study: To evaluate LV mechanical dyssynchrony and LV function in different pacing modes after permanent cardiac pacing by using TDI and speckle tracking echocardi-ography and to correlate these changes with other clinical, electrocardiographic and echocardiographic data.Patients and Methods: Seventy patients were enrolled in this prospective cross sectional observational study, (mean age 60.99±13.77 years, 42 females), in Mansoura Specialized Medical Hospital over a period of 1 year from April 2018 to April 2019. All patients were assessed by thorough history taking, clinical examination, 12 lead surface ECG, echocar-diography, 2D speckle tracking echocardiography STE to assess GLS and tissue Doppler imaging TDI.Results: Regarding diastolic function by pulsed wave Doppler PWD: There was significant decrease in E/e¢ ratio (p<0.001 *), significant increase in myocardial performance index Tei index (p<0.001 *). Regarding internal dimensions and systolic function: There was significant increase in the following: Left Atrial Dimension (LAD) (p=0.001*), Left Ventricular End Systolic Dimension LVESD (p<0.001*) and Left Ventricular End Diastolic Dimension LVEDD (p<0.001 *) while there was significant decrease in ejection fraction EF (p<0.001 *) and fractional shortening FS (p<0.001 *). Regarding parameters of LV dysynchrony: There was significant increase in the following: Aortic preejection delay APED (p<0.001*), interventricular mechanical delay (p<0.001 *) and septal posterior wall motion delay SPWMD by M mode (p<0.001 *). Regarding parameters assessed by tissue synchronization imaging TSI: There was significant increase in the following: SD-Ts (p=0.001 *) and all segments Max delay (p=0.027*). Regarding parameters assessed by STE: There was significant decrease in global longitudinal strain GLS (p=0.034*) while there was significant increase in TP-SD by STE (p<0.001*).Also, there was significant decrease in global longitudinal strain GLS (p<0.001*) and significant increase in TP-SD by STE (p=0.001*) in DDD group. While there was significant decrease in global longitudinal strain GLS (p<0.001 *) and significant increase in TP-SD by STE (p<0.001*) in VVI group.Conclusion: GLS and 2D STE can help in the detection of subclinical left ventricular dysfunction after permanent pacemaker implantation before appearance of symptoms. Also, cardiac pacing leads to LVMD whatever the pacing mode is which may needs later on upgrading to cardiac resynchronization therapy CRT.

Regarding High-Intensity Interval Training and Left Ventricular Mechanics.

Dear Editor in Chief, The influence of exercise on the mechanical function of the heart has become a topic of considerable interest over the past decades. In a recent issue of Medicine and Science in Sports and Exercise, Huang et al. (1) report on a study that investigated the effects of high-intensity interval training (HIIT) on echocardiographic-derived indices of left ventricular (LV) mechanical function in young, sedentary, but otherwise healthy men. We believe that this study has the potential to further our understanding on how the heart responds to exercise, and it ultimately fits within the current knowledge on exercise-induced cardiac adaptation in health and disease (2). However, given the data and the conclusions derived from them, we would appreciate additional details from the authors on the methodology used that may have contributed to the unusually large increase in cardiorespiratory fitness after a very short HIIT intervention and the exceptionally low values derived from speckle tracking echocardiography.

4934Biventricular global and regional strain measured by cardiovascular magnetic resonance based tissue tracking

Abstract Background CMR based tissue tracking (CMR-TT), considered as a novel modality, provides additional insight into left and right ventricular (LV/RV) mechanical function and deformation. The vendor-specific reference values of global and regional strains for volunteers without history of cardiovascular disease are necessary as an important step in clinical routine to help detect early abnormality. Purpose To determine the reference value of LV/RV multi-dimensional global and segmental strains and diagnostic specificity of global longitudinal peak strain (GLS). Biventricular global and segmental radial, circumferential and longitudinal systolic peak strains (GRS, GCS, GLS and SRS, SCS, SLS) of 150 healthy adults in three age subgroups (G20–40, G41–60 and G61–80) were derived by post-hoc imaging software in standard steady-state free precession cine images acquired at 1.5T. LV strains were calculated with three-dimensional (3D) CMR-TT in the modified AHA 16-segment model via a short-axis stack and long axis 2-, 3-, 4-chamber cine images, and RV strains were generated with 2D CMR-TT via 4-chamber cine images. Results The reference values of LV global peak strains resulted as 44.4±13.0% for GRS, −17.0±2.7% for GCS, and −15.4±2.3% for GLS, respectively. RV-GLS was measured as −24.9±5.1%. Global and segmental strains might differ between males and females. Females showed significant age-associated difference of LV global peak strains (P&lt;0.05) as the opposite of males (Figure 1). Females also presented higher magnitude of LV global peak strains than males in the eldest group G61–80 (P&lt;0.05). Unlike LV, no age-associated difference of RV-GLS was detected in both gender groups. However, females showed less negative RV-GLS than males in G20–40 and more negative RV-GLS than males older than 40 years old (P&lt;0.05). The local discrepancy of biventricular SRS, SCS and SLS was observed. It seemed that LV mid-cavity played a more essential role on LV shortening (more negative SCS and SLS) than wall thickening (smaller SRS) compared with base and apex. RV basal and mid SLS, derived from segment 1–4, was more negative than apical SLS derived from segment 5–6. The specificity of LV- and RV-GLS cut-off value (mean value+1.96*standard deviation) generated from the vendor-, age- and gender-specific reference value in evaluating heart contractile function reached 97.3% and 94.7%, respectively. Conclusions Considering the vendor-, gender- and age-associated difference of biventricular global strains, specific reference values need to be established to facilitate the wide application of strain in clinical routine. Meanwhile, segmental strains are also fundamental for detecting local abnormality of myocardial deformation.

P613Cardiac magnetic resonance imaging derived left ventricular mechanical function in patients with atrial fibrillation and left atrial low voltage zones

Abstract Background The relation of left atrial low voltage zones (LVZ) to left ventricular function in patients undergoing pulmonary vein isolation (PVI) is not known. Objective To explore the relationship of left atrial low voltage zones (LVZ) on left ventricular function in patients with atrial fibrillation. Methods From June to Nov. 2018, 107 (mean age 67y, 70 men, 73 persistent AF) consecutive patients with symptomatic AF underwent a PVI with LVZ mapping. Before PVI the left ventricular ejection fraction (EF) and stroke volume (SV) were measured by cardiac magnetic resonance imaging (CMR). From feature-tracking of CMR-cine images left ventricular global, systolic and diastolic longitudinal strains (GLS), circumferential strains (GCS) and radial strains (GRS) were calculated. Results Of 59 patients CMR scanning in sinus rhythm was performed, LVZ were present in 24 patients. LVEF was significantly lower in patients with left atrial LVZ (62±9% vs. 55±15%) (p=0,03). Left ventricular stroke volume was significantly decreased by the extent of LVZ (94±23 vs. 72±21ml), (p=0,03). The left ventricular diastolic strains during ventricular filling (caused by atrial contraction) of GLS (r=−0,52), GCS (r=−0,65) and GRS (r=−0,65) were highly signifcantly correlated to the occurence and extent of LVZ (each p&lt;0,001 respectively). The only systolic ventricular strain was GLS, which decreased (r=−0,3, p=0,03) by the occurance of atrial low voltage. Conclusion The active, atrial part of diastolic left ventricular filling properties is impaired by the occurrence and extent of left atrial LVZ. In patients with left atrial LVZ the left ventricular stroke volume and ejection fraction is decreased already in sinus rhythm. It seems possible that atrial mechanical dysfunction and presence of atrial low voltage maybe predicted by LV diastolic strain analysis.

P2608Impact of sub-clinical systolic dysfunction on exercise hemodynamics in HFpEF: time to integrate diastolic and systolic indices

Abstract Background A potential role for subclinical systolic impairment as a contributor to the pathophysiology and outcomes of heart failure with preserved ejection fraction (HFpEF) has been proposed recently. However, the precise relationship of indices of systolic dysfunction with exercise hemodynamics in HFpEF is not known. In this study, we characterize the relationship between left ventricular mechanical function assessed by strain imaging with the key hemodynamic features of HFpEF at rest and during exercise. Methods Simultaneous echocardiography and exercise right heart catheterization was performed in 90 subjects (68 HFpEF, 22 control) referred for assessment of dyspnea. HFpEF was defined as left ventricular ejection fraction (LVEF) ≥50% with a pulmonary capillary wedge pressure (PCWP) ≥15mmHg at rest and/or ≥25mmHg at maximal exertion. Measures of left ventricular strain were taken using speckle tracking and analyzed together with natriuretic peptides and rest and exercise hemodynamics. Results At rest, HFpEF patients had impaired GLS compared to NCD subjects (−18.4±2.5 vs −21.2±3.5%, p≤0.001. Ejection fraction was similar (62±6 vs 61±6%, p=0.81). With worsening global longitudinal strain, patients with HFpEF displayed a worse cardiac index at both rest and exercise (p&lt;0.001 for both), but similar filling pressure (p=0.85). The tertile with the worst strain had the highest level of natriuretic peptide. The association of strain with peak cardiac index was independent of LVEF, BNP, age, LAVI, LVMI, and systolic blood pressure. Conclusions Despite a preserved ejection fraction, a proportion of patients with HFpEF display impaired GLS, which correlates with a worse cardiac output. Impaired GLS was not associated with higher filling pressures at rest or exercise. Acknowledgement/Funding National Heart Foundation of Australia