Structural Remodeling Of Left Atrium Research Articles

Reverse remodeling of left atrium assessed by cardiovascular magnetic resonance feature tracking in hypertrophic obstructive cardiomyopathy after septal myectomy

BackgroundAssessing the structure and function of left atrium (LA) is crucial in hypertrophic obstructive cardiomyopathy (HOCM) because LA remodeling correlates with atrial fibrillation. However, few studies have investigated the potential effect of myomectomy on LA phasic remodeling in HOCM after myectomy using cardiovascular magnetic resonance (CMR) feature tracking (FT). This study aims to evaluate the LA structural and functional remodeling with HOCM after myectomy by CMR-FT and to further investigate the determinants of LA reverse remodeling. MethodsIn this single-center study, we retrospectively studied 88 patients with HOCM who received CMR before and after myectomy between January 2011 and June 2021. Preoperative and postoperative LA parameters derived from CMR-FT were compared, including LA reservoir function (total ejection fraction [EF], total strain [εs], peak positive strain rate [SRs]), conduit function (passive EF, passive strain [εe], peak early negative strain rate [SRe]) and booster function (booster EF, active strain [εa], late peak negative strain rate [SRa]). Eighty-six healthy participants were collected for comparison. Univariate and multivariate linear regression identified variables associated with the rate of change of εa. ResultsCompared with preoperative parameters, LA reservoir function (total EF, εs, SRs), booster function (booster EF, εa, SRa), and SRe were significantly improved after myectomy (all P < 0.05), while no significant differences were observed in passive EF and εe. Postoperative patients with HOCM still had larger LA and worse LA function than healthy controls (all P < 0.05). After analyzing the rates of change in LA parameters, LA boost function, especially εa, showed the most dramatic improvement beyond the improvements in reservoir function, conduit function, and volume. In multivariable regression analysis, minimum LA volume index (adjusted β = − 0.39, P < 0.001) and Δleft ventricular outflow tract (LVOT) pressure gradient (adjusted β = − 0.29, P = 0.003) were significantly related to the rate of change of εa. ConclusionsPatients with HOCM after septal myectomy showed LA reverse remodeling with a reduction in LA size and restoration in LA reservoir and booster function but unchanged LA conduit function. Among volumetric and functional changes, booster function had the greatest improvement postoperatively. Besides, preoperative LAVmin index and ΔLVOT might be potential factors associated with the degree of improvement in εa.

Left atrial remodeling in heart failure: the role of sphericity index (the SPHERICAT-HF study).

Left atrial sphericity index (LASI) is an echocardiographic index easily obtained; its use in patients with heart failure (HF) has never been investigated so far. This single-centre study aimed to investigate the usefulness of LASI in an unselected cohort of patients hospitalized for acute HF, and its potential correlation with the amino-terminal portion of pro-B-type natriuretic peptide (NT-proBNP) levels and with New York Heart Association (NYHA) functional class. Ninety-four consecutive HF patients underwent a transthoracic echocardiogram with a detailed study of the left atrium (LA) including LASI (calculated from the apical four-chamber view as the ratio between the transverse and longitudinal diameters), and blood tests (including NT-proBNP) on the same day. Median age was 75.5 (interquartile range-IQR 62-82) years and 55% were males, 58.5% had a NYHA class III-IV, and median NT-proBNP was 3284 (IQR 1215-7055) pg/ml. The LA was dilated in 94%, and median biplane LA volume index was 62ml/m2. Patients with advanced NYHA class showed more advanced LA remodeling. Mean LASI was 0.78 ± 0.09 and did not correlate with NT-proBNP levels (r 0.03; p 0.75) or with patient NYHA class (R2 0.011; p 0.287). None of the echocardiographic indices of LA structural and functional remodeling proved to be independently associated with a high NYHA class on multivariate regression analysis. In conclusion, LA remodeling is almost invariably present in patients with HF. LASI does not correlate with NT-proBNP levels or with NYHA functional class. Further studies are needed to describe the complex patterns of atrial remodeling in HF.

EARLY AND CONTINUOUS DETECTION OF LEFT ATRIAL PHASIC DYSFUNCTION IN THE PROGRESSION OF HYPERTENSIVE CARDIAC REMODELING

Objective: Objective: The left atrium (LA) modulates left ventricular (LV) filling and cardiovascular performance with its reservoir, conduit, and booster pump functions. We used two dimensional speckle tracking echocardiography (2DSTE)-based strain and strain rate to evaluate LA mechanics in hypertensive patients with or without LA/LV structural remodeling. Design and method: Design and Method: We enrolled 30 healthy controls (Group I) and 302 HT patients, and we divided HT patients according to LV and LA structural remodeling. Group II (n = 101), HT without LVH and LA volume index (LAVI) &lt; 28 mL/m2; Group III (n = 82), HT without LVH and LAVI &gt; 28 mL/m2; Group IV (n = 98), HT with LVH and E/e‘ &lt; 13; Group V (n = 21), HT with LVH and E/e‘ &gt; 13. The strain and strain rate images were studied, and the following parameters were measured: LA reservoir strain and strain rate (LAS-S, LASR-S), LA conduit strain and strain rate (LAS-E and LASR-E), LA booster strain and strain rate (LAS-A and LASR-A). LA stiffness index (LASI) was defined as the ratio of E/e‘ to LAS-S. Results: Results: LASI was significantly higher in Group II than Group I (p &lt; 0.05), and further increased in Group III and IV. LASI is the highest in Group V (p &lt; 0.001 vs Group I and II, p &lt; 0.05 vs Group III and IV). Generally, All strain and strain rate parameters, including LAS-S, LASR-S, LAS-E, LASR-E, LAS-A and LASR-A, gradually and significantly decreased from Group I to Group V. We also explored the correlation between LASI and cardiovascular risk factors as well as the other markers of TOD in HT. LASI was correlated with age, diabetes, hemoglobin A1c, systolic blood pressure, BMI, LVMI, Ma/Cre, carotid IMT, PWV, Triglycerides and eGFR. Multivariate regression analysis revealed that age, BMI, PWV and Ma/Cre were independent factors related to LASI. Conclusions: Conclusions: The abnormality of LA mechanics precedes LA enlargement and LVH in HT, and strain-derived LA phasic function declined further along with LA and LV remodeling and diastolic dysfunction. LASI can be identified as a detective biomarker of left cardiac remodeling and diastolic dysfunction in HT.

Enhanced monocyte migratory activity in the pathogenesis of structural remodeling in atrial fibrillation.

Pathophysiological roles of monocytes in atrial fibrillation (AF), particularly for the progression of structural remodeling of the left atrium (LA), remain elusive. This study examined the association between the characteristics of circulating and local monocytes and extent of structural remodeling in LA, gauged by LA size, in AF patients. First, 161 AF patients who were referred for catheter ablation were enrolled and divided into two groups according to the median of LA diameter (≤39 mm: normal LA group, >39 mm: enlarged LA group). As a control group, 22 patients underwent catheter ablation for paroxysmal supraventricular tachycardia (PSVT) without history of AF were analyzed. Blood samples were collected for flow cytometric analyses to evaluate monocyte subsets based on the levels of CD14 and CD16. Moreover, monocytes were isolated from blood to measure CC chemokine receptor 2 (CCR2) transcripts and protein levels, and migratory activity toward monocyte chemoattractant protein 1 (MCP-1). Second, to characterize the local monocytes in the atrial wall in AF, the resected left atrial appendages (LAA) in AF patients underwent cardiac surgery were histologically evaluated (n = 20). The proportions of monocyte subsets based on CD14 and CD16 expressions were not significantly different between the normal and enlarged LA group. Both transcripts and total protein levels of CCR2 in monocytes were higher in the enlarged LA group compared to those in the normal LA group. In the enlarged LA group, monocytes exhibited more enhanced migratory activity than the normal LA group. Moreover, we found a significantly higher number of CCR2-positive monocytes/macrophages in the LAA in the enlarged LA group. Enhanced migratory activity in circulating and local monocytes may play a pivotal role in the pathogenesis of progression in atrial remodeling in AF patients.

Left atrial emptying fraction determined during atrial fibrillation predicts maintenance of sinus rhythm after direct current cardioversion in patients with persistent atrial fibrillation.

Echocardiography is the basic imaging technique used to determine the odds of maintaining sinus rhythm (SR) following direct current cardioversion (DCCV) for persistent atrial fibrillation (AF). However, most studies are focused on the echocardiographic parameters obtained during SR resulting from successful DCCV. The aim of this study was to assess the value of the echocardiographic parameters measured before DCCV for the prognosis of SR maintenance after DCCV. The study included 146 patients with persistent AF who underwent DCCV. Clinical and echocardiographic data were collected directly before DCCV and, for patients with SR, one month, six months, and 12 months after DCCV. We found that left atrial emptying fraction (LAEF) assessed during atrial fibrillation was significantly larger in the group with SR maintenance after 12 months than in the group with AF recurrence (30.8±8.3 vs. 24.6±10.4%; p<0.001). In multivariable logistic regression analysis with a model containing echocardiographic parameters, LAEF (OR 1.053; 95% CI 1.011-1.096; p = 0.013) and the E/e'mean ratio (OR 0.883; 95% CI 0.788-0.990; p = 0.033) were independent predictors of SR maintenance. Analyzing a model including clinical and echocardiographic variables, only LAEF (OR 1.046; 95% CI 1-1.095; p = 0.049) and beta-blockers used before DCCV (OR 14.694; 95% CI 1.622-133.139; p = 0.017) were independent predictors of SR maintenance after 12 months. Our results indicate that LAEF measured during AF is a significant predictor of SR maintenance in the 12 months following DCCV due to persistent AF. Our findings confirm the recently raised hypothesis about the superiority of echocardiographic parameters assessing mechanical remodeling over parameters assessing structural remodeling of left atrium in predicting sinus rhythm maintenance after electrical cardioversion.

P2861Elevated cc chemokine receptor 2 expression and higher migratory activity of monocytes in atrial fibrillation patients with progressive structural remodeling

Abstract Background Inflammation in atrial tissue underlies structural remodeling of left atrium, which is a hallmark of atrial fibrillation (AF). Activated monocytes mediate inflammation; however, the role of monocytes in AF pathogenesis has not been extensively examined. In this study, we thus investigated the association between structural remodeling of left atrium, represented by left atrial dimension (LAD), and characteristics of peripheral monocytes in patients with AF. Methods Blood samples were collected from patients undergone catheter ablation between July 2017 and October 2018, including AF patients (n=152) and paroxysmal supraventricular tachycardia (PSVT) patients, which serves as a control non-AF group (n=22). AF patients were further divided into two groups by the median of LAD (normal LAD group: LAD &lt;40 mm, n=77, large LAD group: LAD ≥40 mm, n=75). Peripheral blood mononuclear cells (PBMC) were isolated to analyze monocyte subsets by flow cytometry. In a subset of patients, we further isolated monocytes from PBMC by using magnetic bead-based negative selection method then gene products associated with inflammation or monocyte functions were evaluated. We also examined migratory activity of monocytes toward monocyte chemotactic protein-1, a ligand for CC chemokine receptor 2 (CCR2), using a modified Boyden chamber method. Finally, we performed immunofluorescence staining of monocytes and macrophages in left atrial appendages resected from patients underwent coronary bypass graft surgery (CABG) complicated by AF. Results There were no differences in age, body mass index and high-sensitivity C-reactive protein levels among three groups, including non-AF, normal LAD and large LAD groups, except that more female subjects were included in non-AF group. We found that proportions of classical CD14++CD16- and nonclassical CD14+CD16++ monocytes were higher (non-AF: 71.2±7.3% vs. AF: 75.5±8.3%, p&lt;0.05) and lower (non-AF: 16.4±5.9% vs. AF: 13.2±5.5%, p&lt;0.05), respectively, in all AF patients compared with those in non-AF group, while no significant difference was observed between normal and large LAD groups. In monocytes from large LAD group, mRNA levels of CCR2, a receptor to mediate monocyte chemotaxis, were significantly higher compared to those in normal LAD group (Figure A, p&lt;0.05). Furthermore, monocytes isolated from large LAD group exhibited higher migratory capacity compared to normal LAD group (Figure B, p&lt;0.01). Finally, higher monocyte/macrophage infiltrations to left atrial appendages were implicated in patients with large LAD, shown by immunofluorescence staining. Conclusions Monocytes in AF patients with enlarged left atrium expressed higher CCR2 mRNA and were more active in chemotaxis to MCP-1, suggesting the proactive roles of activated monocytes in the pathogenesis of arterial remolding in AF.

P3767Progressive left atrial remodeling associates with cholesterol efflux capacity of HDL in atrial fibrillation patients

Abstract Background The clinical significance of high-density lipoprotein (HDL) function, represented by cholesterol efflux capacity (CEC), in addition to serum HDL cholesterol (HDL-C) levels, has been recognized in the pathogenesis and prognosis in patients with atherosclerotic cardiovascular diseases. However, the roles of HDL in the development and the progression of atrial fibrillation (AF), has been rarely evaluated. In this study, we thus hypothesized that the compromised HDL function may be associated with the progression of pathological structural remodeling in left atrium (LA). Objective We explored the association between CEC of HDL and the left atrial dimension (LAD), a maker of structural remodeling in the LA, in patients with AF and control. Methods This is a single center case-control study including consecutive 260 AF patients (AF group) and 34 paroxysmal supraventricular tachycardia (PSVT) patients (PSVT group, served as a control group), who underwent catheter ablation from July 2017 to December 2018. Blood samples were collected before catheter ablation procedure. CEC of HDL was measured by using ex vivo radiotracer system that involved incubation of [3H] cholesterol-loaded J774.1 murine macrophage-like cells with apoB-depleted serum. Results Serum HDL-C level was lower in AF group compared to those of PSVT group (55.3±15.3mg/dl vs 61.7±13.3mg/dl: p=0.024). As a marker of HDL function, CEC of HDL was significantly lower in patients with AF group compared to those in PSVT patients (4.74±0.84% vs 5.20±0.99%: p=0.005, Fig 1). In all patients including both groups, CEC of HDL was inversely correlated with LAD (r=−0.25; p&lt;0.001, Fig 2), indicating the inverse association between HDL function and the progression of structural remodeling in AF. Moreover, multivariate logistic regression analysis adjusted by age, gender, body mass index, ejection fraction, and HDL-C demonstrated that increase in CEC of HDL was associated with the lower risk to be highest quartiles of LAD (&gt;42mm), even adjusted by serum HDL-C levels (odds ratio of 1-SD elevation in CEC of HDL for LAD&gt;42mm: 0.63; 95% confidence interval: 0.40–0.97, p=0.037), which implicated the link between HDL function and progression of left atrial structural remodeling. Conclusion Findings in this study may suggest that compromised HDL functionality is associated with the pathogenesis of left atrial structural remodeling in AF patients.

PP.04.01] LEFT ATRIUM FUNCTION IN SYSTEMIC ARTERIAL HYPERTENSION

Objective: Assessment of left atrium (LA) mechanic by 2-Dimensional Speckle tracking Imaging (STI) recently has been discussed as useful method for LA function estimation. The purpose of this study was to assess the relationship between LA function (particularly reservoir function) and LA structural remodeling in patients with systemic arterial hypertension. LA evaluation was made using conventional echocardiography, tissue Doppler, and 2-Dimensional STI. Design and method: 48 hypertensive patients without left ventricular hypertrophy and 36 healthy controls (age and gender matched), underwent routine transthoracic echocardiography and speckle tracking echocardiography of the left atrium. LA volume was calculated by the biplane Simpson's method. Peak early diastolic transmitral flow velocity, peak early diastolic mitral annular motion velocity (E/E1) and peak systolic LA strain were messured. Results: LV Mass was 132.7 ± 16.5 grams in control and 180.2 ± 60.4 grams in the hypertensive patients. Left atrium volume indexed to body surface area was 19.4 ± 5.4 versus 29.4 ± 4.3 ml/m2 in controls and hypertensive subjects respectively (p < 0.001). There were also significant differences between the measurements of transmitral flow velocities (E, A), and E/E1 and E/A ratios in both groups. Left atrium anteroposterior diameter was higher in the hypertensive group 4.20 ± 0.58 versus 3.4 ± 0.28 cm in the contols (p < 0.001). Left atrial longitudinal strain was 24.05 ± 3.18 in hypertensive patients and 32.7 ± 2.8 among controls (p < 0.001). Conclusions: Speckle tracking imaging might be assumed as method for early detection of LA function impairment in arterial hypertension.

Zależność między entropią aproksymacji rytmu serca a strukturalną i funkcjonalną przebudową przedsionków oraz przebiegiem klinicznym napadowego i przetrwałego migotania przedsionków

Introduction. Atrial remodeling due to atrial fibrillation (AF) is characterized by electrical and structural changes of cardiomyocytes that are in response for arrhythmia self-perpetuation and resistance to sinus rhythm conversion. This project was designed to study nonlinear methods of heart rate variability (HRV) (such as approximate entropy of heart rate [ApEn]) that can best characterize LA structural and functional remodeling and its association with clinical course in patients with paroxysmal and persistent AF. Material and methods. Traditional time and frequency domain HRV indices were analyzed in 75 patients (mean age 55 [49–62] years, 79% male) with paroxysmal or persistent AF on a background of ischemic heart disease (IHD) and/or hypertension without significant structural myocardial damage and in 19 control patients without AF (mean age 56 [49–61] years, 63% male). Echocardiography was performed to assess size and function of left atrium (LA). Results. In patients with paroxysmal or persistent AF the ApEn value was significantly lower than in the control patients group. Echo-parameters of LA, characterizing its structure and function, were correlated with ApEn value. The AF duration was negatively correlated with the ApEn value. Its values less than 0.93 was associated with a larger LA size (> 39 mm) and more frequent AF. Conclusions. There is a strong correlation of ApEn value and atrial remodeling. ApEn values less than 0.93 are related to AF recurrence and can be considered as prognostic risk factor of structural and functional remodeling of the heart muscle in patients with AF.

Left atrium in cardiac resynchronization therapy: Active participant or innocent bystander

BackgroundCardiac resynchronization therapy (CRT) is an established treatment for patients with advanced heart failure that results in improvement of left ventricle (LV) systolic function and LV reverse remodeling. This may have a positive effect on the size and the function of the left atrium (LA). We assessed the LA function, dimensions, and volumes before and after CRT implantation. MethodsA total of 37 patients with mean age of 55.3±9.64years including 11 (29.7%) females, having symptomatic heart failure [ejection fraction (EF) <35%, left bundle branch block >120ms, with New York Heart Association III or ambulatory class IV] were enrolled, and underwent CRT implantation. M-mode, two-dimensional (2D) echocardiography, tissue Doppler imaging, and 2D strain (ɛ) imaging were done assessing LV volumes, ejection fraction, and diastolic function, LA diameter, area, maximal and minimal volumes, LA EF, and longitudinal strain (ɛ). Patients were reassessed after 3months. A reduction in LV end-systolic volume of ≥10% was defined as volumetric responders to CRT. Patients with decompensated New York Heart Association class IV, sustained atrial arrhythmias, rheumatic or congenital heart diseases, nonleft bundle branch block, and those who were poorly echogenic, were excluded. ResultsTwenty-four (64.8%) patients were volumetric responders (group A). Both groups were matched regarding demographic, clinical, electrocardiographic, and echocardiographic criteria apart from the LA dimension and volumes which were significantly lower in the responders group prior to CRT. At the end of the follow-up, only the responders group had further significant reduction in LA diameter (41.6±1.67 vs. 43.88±1.82mm, p<0.01), maximal volume (62.2±18.3 vs. 73.04±21.78ml, p<0.01), minimal volume (32.6±12.3 vs. 41.8±13.97, p<0.01), together with a significant increase in LA EF (48.3±11.3 vs. 41.99±13.9, p<0.01), positive longitudinal strain (16.59%±5.89 vs. 12.45%±6.12, p<0.01), and negative longitudinal strain (−3.3±1.9 vs. −1.62±1.2, p<0.01) compared to baseline readings, a finding that was not present in the nonresponders group. In addition, atrial fibrillation was significantly higher in the nonresponders group. Baseline LA diameter and volumes were found to be independent predictors of response to CRT by multivariate analysis. ConclusionsCRT induces LA anatomic, electrical, and structural reverse remodeling that could be assessed by conventional 2D echocardiography and 2D (ɛ) strain imaging. LA dimension and volumes were independent predictors of response to CRT and can help in selection of candidates for it.

Long-Term Outcome of Left Atrial Voltage-Guided Substrate Ablation During Atrial Fibrillation: A Novel Adjunctive Ablation Strategy.

Left atrium (LA) low voltage area (LVA) on 3-D electroanatomic bipolar voltage mapping (EAVM), as a surrogate for scar, is associated with poor AF ablation outcome. We evaluated the long-term outcome of an LVA-guided atrial fibrillation (AF) substrate modification strategy as an adjunct to pulmonary vein isolation (PVI). Two hundred and one consecutive patients with AF (82% persistent/Non-PAF, age 65 years), who underwent EAVM during AF prior to PVI, were divided into 2 groups according to the presence or absence of LVA outside the PV antra, defined as bipolar voltage of <0.5 mV. LVA-guided substrate modification was performed after PVI in patients with LVA. LVA was found in 159 patients (79%). Non-PAF (OR 3.851, P = 0.002) and CHA2 DS2 -VASc score (OR 1.815, P < 0.001) were independent predictors for the LVA. After the index procedure, 144 patients (72%) were free from AF at 12 months. With multiple procedures, 148 patients (74%) during a median follow-up of 3.1 years were free from the recurrence. There was no difference in the recurrence (log-rank P = 0.746), and complications (0% vs. 7%, P = 0.125) between the groups. Neither LVA nor Non-PAF was an independent predictor for the recurrence in a multivariate analysis. Patients with LVA had an equally favorable long-term ablation outcome compared to those without. As an adjunct to PVI, voltage-guided substrate modification may be an important ablation strategy in patients with LA structural remodeling.

Association of β1-Adrenergic, M2-Muscarinic Receptor Autoantibody with Occurrence and Development of Nonvalvular Atrial Fibrillation.

Atrial fibrillation (AF) is the most common sustained arrhythmia and is independently associated with increased risk of stroke and death. Although the exact mechanisms of AF are not completely elucidated, a large number of evidences demonstrate that autoimmunity may play an important role in the initiation, the progression, and the maintenance of AF. In this study, we aimed to compare anti-β1-adrenergic receptor autoantibody (anti-β1-R) and anti-M2-muscarinic receptor autoantibody (anti-M2-R) levels between nonvalvular AF patients and healthy control subjects. The levels of serum anti-β1-R, antinuclear antibodies, and anti-M2-R were measured in both groups by enzyme-linked immunosorbent assay (ELISA). High-sensitivity C-reactive protein (hs-CRP) and interleukin (IL)-6 concentration were measured, respectively, by immunoturbidimetry and chemiluminescence. Anti-β1-R and anti-M2-R levels were significantly higher in patients with nonvalvular AF than in healthy controls (anti-β1-R 221.11 [132.38-291.69] ng/mL vs 198.14 [125.70-278.40] ng/mL, P < 0.01; anti-M2-R 271.81 [144.99-378.20] ng/mL vs 235.01 [121.53-358.99] ng/mL, P < 0.01). Compared with the control group, the serum levels of IL-6 and hs-CRP were higher in the nonvalvular AF group (IL-6 19.65 ± 5.6pg/mL vs 6.79 ± 1.09 pg/mL, hs-CRP 6.03 ± 1.35 mg/L vs 2.73 ± 0.63 mg/L, P < 0.05). Antinuclear antibody (ANA) levels were similar between two groups (ANA 10.55 [1.86-271.8] U/mL vs 10.49 [1.303-161.7]U/mL, P > 0.05). The baseline value of serum anti-β1-R (odds ratio [OR]: 13.176, P < 0.001), anti-M2-R (OR: 4.41, P < 0.001), IL-6 (OR: 6.126, P < 0.05) levels, and left atrial diameter (OR: 5.781, P < 0.05) were independent predictors of nonvalvular AF by multivariable analyses. We found a significant association between circulating serum anti-β1-R, anti-M2-R, IL-6 levels, and nonvalvular AF. We presume that the autoimmunity and inflammation might take part in electrical remodeling and structural remodeling of left atrium.

Abstract 11153: Association of β1-Adrenergic,M2-Muscarinic Receptor Autoantibody With Occurrence of Nonvalvular Atrial Fibrillation

Introduction: Atrial fibrillation (AF) is the most common sustained arrhythmia and confers an independent increased risk of stroke and death. Although the exact mechanisms behind AF are not completely elucidated, A large number of evidence demonstrates that autoimmunity may play an important role in the initiation, the progression and the maintenance of AF. Hypothesis: In this study, we aimed to compare anti-β 1 -R and anti-M 2 -R levels between non-valvular AF patients and healthy control subjects Methods: Seventy-one patients with non-valve atrial fibrillation(age: 62.69±11.23 years, 54% male),along with 71healthy control subjects(age: 61.86±11.90 years, 52% male) were included . Enzyme-linked immunosorbent assay tests to measure serum anti-β 1 -R and anti-M 2 -R levels were performed in both groups. Hs-CRP concentration was measured by immunoturbidimetry.IL-6 concentration was measured by chemiluminescence. Results: Anti-β 1 -R and anti-M 2 -R levels were significantly higher in patients with non-valvular AF compared to healthy controls[anti-β 1 -R 221.11(132.38-291.69) vs. 198.14(125.70-278.40) ng/ml, P&lt;0.01; anti-M 2 -R 271.81(144.99-378.20) vs. 235.01(121.53-358.99) ng/ml, P&lt;0.01]. Compared with the control group, the serum level of IL-6,hs-CRP were higher in the non-valvular AF group(IL-6 19.65±5.6pg/mL vs 6.79±1.09pg/mL,hs-CRP 6.03±1.35mg/Lvs 2.73±0.63mg/L P&lt;0.05).After multivariable analyses , the baseline value of serum anti-β 1 -R (OR: 13.176, p&lt;0.001),anti-M 2 -R (OR:4.41, p&lt;0.001),IL-6(OR:6.126, p&lt;0.05) levels and LA diameter(OR:5.781, p&lt;0.05) were independently predictors of non-valvular AF. Conclusions: We found a significant association between circulating serum anti-β1-R,anti-M2-R,IL-6 levels and non-valvular AF. The possible mechanism is that the autoimmunity and inflammation might take part in electrical remodeling and structural remodeling of left atrium. Larger studies are warranted to further investigate their role in these settings.

A Computational Framework for Personalized Blood Flow Analysis in the Human Left Atrium

Atrial fibrillation (AF), the most common human arrhythmia, is a marker of an increased risk of embolic stroke. However, recent studies suggest that AF may not be mechanistically responsible for the stroke events. An alternative explanation for the mechanism of intracardiac thrombosis and stroke in patients with AF is structural remodeling of the left atrium (LA). Nevertheless, a mechanistic link between LA structural remodeling and intracardiac thrombosis is unclear, because there is no clinically feasible methodology to evaluate the complex relationship between these two phenomena in individual patients. Computational fluid dynamics (CFD) is a powerful tool that could potentially link LA structural remodeling and intracardiac thrombosis in individual patients by evaluating the patient-specific LA blood flow characteristics. However, the lack of knowledge of the material and mechanical properties of the heart wall in specific patients makes it challenging to solve the complexity of fluid-structure interaction. In this study, our aim was to develop a clinically feasible methodology to perform personalized blood flow analysis within the heart. We propose an alternative computational approach to perform personalized blood flow analysis by providing the three-dimensional LA endocardial surface motion estimated from patient-specific cardiac CT images. In two patients (case 1 and 2), a four-dimensional displacement vector field was estimated using nonrigid registration. The LA blood outflow across the mitral valve (MV) was calculated from the LV volume, and the flow field within the LA was derived from the incompressible Navier-Stokes equation. The CFD results successfully captured characteristic features of LA blood flow observed clinically by transesophageal echocardiogram. The LA global flow characteristics and vortex structures also agreed well with previous reports. The time course of LAA emptying was similar in both cases, despite the substantial difference in the LA structure and function. We conclude that our CT-based, personalized LA blood flow analysis is a clinically feasible methodology that can be used to improve our understanding of the mechanism of intracardiac thrombosis and stroke in individual patients with LA structural remodeling.

LA structural remodeling is predicted by arterial stiffening independently of conventional risk factors

Background Left atrium (LA) size and function are powerful biomarkers of cardiovascular outcomes in many diseases. We sought to determine if the expected age-associated increase in arterial stiffness (AS) and left ventricular (LV)-LA afterload leads to corresponding effects on LA function and this can be measured with cardiovascular magnetic resonance (CMR). Additionally, we investigated the significance of these markers in asymptomatic individuals with cardiovascular risk factors (CRF).

Interatrial septal thickness as a marker of structural and functional remodeling of the left atrium in patients with atrial fibrillation.

Background/Aims:There have been reports that interatrial septal (IAS) thickness is increased in patients with atrial fibrillation (AF). This study was performed to investigate whether IAS thickness determined by transthoracic echocardiography (TTE) represents the amount of left atrium (LA) structural and functional remodeling.Methods:The study population consisted of 104 consecutive patients who underwent catheter ablation (CA) for AF (paroxysmal atrial fibrillation [PAF], 82; persistent atrial fibrillation [PeAF], 22). IAS thickness and left atrium volume (LAV) using TTE, and LA voltage (LAVOL) using 3-dimensional electroanatomical mapping system were assessed during sinus rhythm.Results:IAS thickness was significantly correlated with maximal LAV (LAVmax) (r = 0.288, p = 0.003), mean LAVOL (r = –0.537, p < 0.001), total left atrium emptying fraction (LAEFtotal; r = –0.213, p = 0.030), and active LAEF (LAEFactive; r = –0.249, p = 0.014). IAS thickness was greater in the high-risk group (≥ 2) compared to other groups according to CHA2DS2-VASc score (p = 0.019). During a follow-up of 19.6 months, 23 subjects (22.1%; PAF, 17; PeAF, 6) had recurrence of arrhythmia. Univariate analysis showed that LAVmax, minimal LAV, mean LAVOL, LVEFtotal, LVEFactive, and IAS thickness were associated with recurrence of arrhythmia. However, on multivariate analysis, only mean LAVOL and LAEFactive were independent risk factors for recurrence.Conclusions:Although IAS thickness showed significant correlations with parameters for LA structural and functional remodeling, this parameter alone could not independently predict recurrence of arrhythmia after CA for AF.

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Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: implications for disease progression and response to catheter ablation.

Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease. This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities. Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (≤5% LA wall enhancement), Utah II (>5% to ≤20%), Utah III (>20% to ≤35%), or Utah IV (>35%). Distribution in Utah I to IV was comparable in patients with lone AF and non-lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 ± 8.94 vs. 16.94 ± 11.37) was not significantly different between the 2 groups (P = .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non-lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P < .001). The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.

Left atrial strain and strain rate in patients with paroxysmal and persistent atrial fibrillation: relationship to left atrial structural remodeling detected by delayed-enhancement MRI.

Atrial fibrillation (AF) is a progressive condition that begins with hemodynamic and/or structural changes in the left atrium (LA) and evolves through paroxysmal and persistent stages. Because of limitations with current noninvasive imaging techniques, the relationship between LA structure and function is not well understood. Sixty-five patients (age, 61.2+/-14.2 years; 67% men) with paroxysmal (44%) or persistent (56%) AF underwent 3D delayed-enhancement MRI. Segmentation of the LA wall was performed and degree of enhancement (fibrosis) was determined using a semiautomated quantification algorithm. Two-dimensional echocardiography and longitudinal LA strain and strain rate during ventricular systole with velocity vector imaging were obtained. Mean fibrosis was 17.8+/-14.5%. Log-transformed fibrosis values correlated inversely with LA midlateral strain (r=-0.5, P=0.003) and strain rate (r=-0.4, P<0.005). Patients with persistent AF as compared with paroxysmal AF had more fibrosis (22+/-17% versus 14+/-9%, P=0.04) and lower midseptal (27+/-14% versus 38+/-16%, P=0.01) and midlateral (35+/-16% versus 45+/-14% P=0.03) strains. Multivariable stepwise regression showed that midlateral strain (r=-0.5, P=0.006) and strain rate (r=-0.4, P=0.01) inversely predicted the extent of fibrosis independent of other echocardiographic parameters and the rhythm during imaging. LA wall fibrosis by delayed-enhancement MRI is inversely related to LA strain and strain rate, and these are related to the AF burden. Echocardiographic assessment of LA structural and functional remodeling is quick and feasible and may be helpful in predicting outcomes in AF.