Spatial transcriptomics in the human left atrial appendage and pulmonary vein sleeve.

PO-02-145 SPATIAL TRANSCRIPTOMICS IN THE HUMAN PULMONARY VEIN SLEEVE

Pulmonary Artery Perforation by Plug Anchoring System After Percutaneous Closure of Left Appendage

Atrial tissue expression of receptor for advanced glycation end-products (RAGE) and atrial fibrosis in patients with mitral valve disease

Subxiphoid Minimally Invasive Epicardial Ablation (Convergent Procedure) With Left Thoracoscopic Closure of the Left Atrial Appendage

Intracardiac expression of markers of endothelial damage/dysfunction, inflammation, thrombosis, and tissue remodeling, and the development of postoperative atrial fibrillation

Contemporary left atrial appendage management during adult cardiac surgery

Introduction Cardiomyocytes in the pulmonary vein (PV) sleeves are a major source of ectopic activity driving atrial fibrillation (AF) and episodes of AF in patients are more prevalent at night. While it is known that circadian clocks within the heart regionally control 24-hour variation in pacemaking and ventricular repolarisation, the mechanisms underlying the nighttime preponderance in AF are unknown. Purpose This study addresses the hypothesis that circadian rhythms exist in the pro-arrhythmic activity of PV cardiomyocytes. Methods Male Wistar rats maintained in a 24-hour cycle of 12-hr light/dark (lights-on at Zeitgeber time, ZT=0; lights-off, ZT12) were subject to terminal general anaesthesia (140 mg/kg Na pentobarbital i.p.) at ZT=0, 6, 12 or 18 hr and the hearts removed. RNA was extracted from left atrial (LA) appendage (LAA) and proximal PV at the LA/PV junction (3 rats per ZT) and RNA sequencing conducted. Reads were mapped to the rat genome, counts normalised and models in which ZT was or was not included as a factor compared (Likelihood Ratio Test, adjusted-P<0.01). Whole-cell current clamp recordings were made from cardiomyocytes isolated from the proximal PV (n=308) and the LAA (n=264) (N=74 rats). The effects of noradrenaline (NA, 1 µM) and acetylcholine (ACh, 1 µM) were examined. Data were plotted against the ZT of the time of recording and fitted to a sine wave to establish circadian rhythmicity (P<0.05, extra-sum-of-squares F-test). The effect of ≥24 hr constant dark in the period immediately before experiment was examined. Data are reported as mean ± standard error. Results The expression of 1368 genes varied significantly with ZT, including circadian clock components (e.g. Bmal1, Per1). PV cells were larger than LAA cells (73±1.6 pF vs 53±1.3 pF, P<0.0001) and had more depolarised resting membrane potential (-69±0.2 mV vs -72±0.1 mV, P<0.0001). Both cell types showed circadian variation in action potential duration at 90% repolarisation (APD90) and frequency of pro-arrhythmic activity. Pro-arrhythmic activity was greatest in PV cells and the frequency was greater during the rest phase (ZT0-12) in both cell types. In contrast, the circadian rhythm in APD90 differed between cell type, with the longest APD­­90 recorded during the active phase in PV cells (ZT12-24) but during the rest phase in LAA cells. Pro-arrhythmic activity was increased by NA and decreased by ACh in both cell types with maximal effect during the rest phase. Conclusion Circadian variation in APD90 and proarrhythmic-activity has been demonstrated in isolated proximal PV and LAA cardiomyocytes, with differences in rhythm between the two cell types. RNA sequencing suggests the presence of peripheral clocks in LAA and PV cardiomyocytes. Understanding these mechanisms is important in development of future therapeutic options for AF.

Background Previous studies have shown that acetylation plays a critical role in regulating the progress of cardiovascular diseases by acetylated histone and non-histones protein. However, the global lysine acetylome during atrial fibrillation (AF) were not fully understood. Purpose The aim of the present study was to identify the underlying mechanisms of AF via profiling of the quantitative changes of global proteomics and lysine acetylome in the left atrial appendage (LAA) tissues from valvular heart disease patients with AF. Methods This study obtained LAA specimens from patients undergoing cardiac surgery for severe valvular heart disease. The LAA specimens were obtained from both 9 patients with AF and with sinus rhythm (SR). The changes of proteome and acetylome in the AF-LAA vs SR-LAA tissues were studied using dimethyl-labeling, HPLC fractionation, affinity enrichment, LC-MS/MS analysis, database Search and bioinformatic analysis. The acetylated levels of each lysine acetylated site were normalized on the basis of the corresponding protein abundance. Results The bioinformatic analysis indicates 294 up-regulated (AF/SR ratio >1.3) proteins and 169 down-regulated (AF/SR ratio <1/1.3) proteins in the AF-LAA vs SR-LAA were detected. Moreover, 3,880 sites in 1,044 proteins were quantified. Motif analysis of the identified acetylated peptides indicated that a total of 14 significantly enriched amino acid sequence motifs from −10 to +10 surrounding the acetylated lysine (Kac) were defined according to 3412 peptides from 1115 proteins. Among the quantified acetylated sites and proteins, 231 up-regulated acetylated sites in 130 proteins and 121 down-regulated acetylated sites in 74 proteins were detected. The enrichment-based clustering analysis showed that energy metabolism and cardiac contraction-related proteins were highly differentially expressed in the AF-LAA vs SR-LAA. Meanwhile, the protein-protein interaction network of the differentially expressed acetylated proteins demonstrated that there were 146 nodes and 569 interactions in the network and quite a lot of interactions in energy metabolism-related proteins and in cardiac contraction-related proteins. Furthermore, the acetylated levels of most differentially expressed energy metabolism-related proteins involving in oxidative phosphorylation, TCA cycle, respiratory ETC, fatty acid metabolism were up-regulated. On the contrary, the acetylated levels of most acetylated sites in differentially expressed cardiac contraction-related proteins including the key contraction proteins were down-regulated. Interaction network of Ac-proteins Conclusions This study details and expands our understanding of the changes of proteome and lysine acetylome in the LAA tissues from valvular heart disease patients with AF. The data suggest important expression differences of acetylated proteins related to energy metabolism and cardiac contraction which may be involved in the matrix of AF formation and maintainence. Acknowledgement/Funding This work was supported by the grants from the National Natural Science Foundation of China (no. 81600273, no. 81570310, no.81770337 and no.81870258)

Atrial Fibrillation Substrate in Heart Failure: Expression Levels of Cardiac Sodium Channel, Connexin 43 and Connexin 40 in the Left Atrium

Comparison of Transesophageal Echocardiography Versus Computed Tomography for Detection of Left Atrial Appendage Filling Defect (Thrombus)

Objective In the cryoballoon ablation (CBA) procedure of atrial fibrillation (AF) , the anatomical variability of the pulmonary veins was an important factor influencing the procedural difficulty. This study was to investigate the anatomical factors that cause procedural difficulty in cryoablation of the left superior pulmonary vein (LSPV) . Methods From January 2017 to April 2018, a total of 826 patients with symptomatic AF who had undergone CBA using second-generation cryoballoon in the Fuwai Hospital were enrolled. According to the definition of LSPV cryoablation difficulty, LSPV needed to be cryoablation≥4 timesto achieve pulmonary vein electrical isolation, and the number of cryoablation accounted for more than 50% of the total number of pulmonary vein, 37 patients. LSPV was cryoablation once, and when the time of pulmonary vein isolation was less than 60 seconds, defined LSPV cryoablation easily, as a control group, 38 cases. The anatomical characteristics, such as whether LSPV was the left common pulmonary vein, diameter of veins, the distance between LSPV ostium to bifurcation, the thickness of ridge between LSPV and left atrial (LA) appendage, the angle between LSPV and LA roof-plane, were analyzed from pre-procedural cardiac computed tomography. Results In the patients with LSPV cryoablation difficulty, the incidence of left common pulmonary vein was higher (41% vs. 5%, P=0.001) . Furthermore the maximum and minimum diameter of veins were significantly larger than those in the control group[ (29.05±5.98) mm vs. (23.41±3.04) mm, P<0.001; (17.82±5.61) mm vs. (15.28±3.43) mm, P=0.020]. Compared to the control group, the thickness of ridge between LSPV and left atrial appendage was thinner[ (5.06±1.30) mm vs. (6.03±1.39) mm, P=0.003]and the angle between LSPV and LA roof-plane was small (23.81°±15.23°vs. 35.50°±12.11°, P<0.001) for thecryoablation difficult group respectively. Multivariate regression analysis showed that the thickness of ridge between LSPV and left atrial appendage and the angle between LSPV and LA roof-plane were highly related to the procedural difficulty (OR=1.677, 95%CI1.025-2.746, P=0.040; OR=1.086, 95%CI 1.019-1.157, P=0.011) . Conclusion During the CBA of atrial fibrillation, the thickness of ridge between LSPV and left atrial appendage was thinner and the angle between LSPV and LA roof-plane was smaller, CBA for LSPV was often more difficult. Key words: Atrial fibrillation; Left superior pulmonary vein; Cryoballoon ablation

BS-515-03 ATRIAL FIBRILLATION ASSOCIATED COMMON INTRONIC RISK VARIANTS IN SYNE2 LEAD TO LOWER EXPRESSION OF NESPRIN-2A1, INCREASED NUCLEAR STIFFNESS AND EARLY AFTER DEPOLARIZATIONS IN CARDIOMYOCYTES

Funding Acknowledgements Type of funding sources: None. Background Atrial fibrillation (AF) is characterized by complex electrical, structural and metabolic remodelling. The mechanisms underlying AF progression from paroxysmal to persistent AF are not fully understood, and studies in cardiomyocytes (CMs) at the paroxysmal stage of AF are lacking. Moreover, most studies have so far investigated right atrial appendage CMs, while left atrial appendage (LAA) CMs may be more informative, as AF is predominantly a left atrial disease. Whether and to what extent electrical remodelling during various AF stages also includes alterations of the (late) sodium current (INa), remains unclear. Moreover, the functional relevance of sodium channel isoforms other than the cardiac Nav1.5, such as the "neuronal" isoform SCN10A/NaV1.8, during the various stages of AF is as yet not fully elucidated. Purpose To investigate peak and late INa remodelling in LAA CMs from patients with paroxysmal and persistent AF and patients in sinus rhythm (SR), as well as the potential contribution of NaV1.8-based current. Methods LAA were obtained from patients in SR (N=18) without a history of AF undergoing cardiac surgery, as well as from patients with paroxysmal (N=12) and persistent AF (N=30). Paroxysmal AF was defined as AF episodes terminating spontaneously within seven days and persistent as AF continuing for more than 7 days but less than 1 year. Peak INa, late INa and action potential (AP) properties were investigated through patch-clamp analysis on single LAA CMs, while qPCR was used to assess SCN5A and SCN10A expression levels in LAA tissue. Results In paroxysmal and persistent AF CMs, AP duration was shorter than in SR CMs. Compared to SR, peak INa (Figure 1A) and SCN5A expression (Figure 1B) were significantly decreased in paroxysmal AF, while they were restored to SR levels in persistent AF. Conversely, while late INa was undetectable in SR and paroxysmal AF, it was significantly increased in persistent AF (Figure 2). Peak and late INa Nav1.8-based current was not detected in persistent AF CMs. Similarly, expression of SCN10A was not observed in LAAs at any stage. Conclusions Our study is the first to show that AP shortening already occurs in LAA CMs from paroxysmal AF, potentially contributing to pro-arrhythmia in this early stage of the disease. Moreover, our findings demonstrate that INa is differentially remodelled during various stages of AF, with peak INa reduction occurring during paroxysmal AF, while late INa is increased in persistent AF only. Finally, we have shown that Nav1.8 current does not contribute to the AF-related alterations in INa. These observations are of particular relevance when considering potential pharmacological approaches targeting (late) INa in patients with distinct forms of AF.

ObjectiveAssessing whether serum Vascular Cell Adhesion Molecule 1(VCAM-1) concentration in the left atrial appendage(LAA) and the expression of VCAM-1 in LAA tissues are associated with the risk of atrial fibrillation-related stroke.MethodBlood samples were collected from atrial fibrillation(AF) patients scheduled for catheter ablation of AF, both from within the LAA and peripheral veins(PV). The serum concentration of VCAM-1 was quantitatively analyzed using ELISA. Additionally, LAA tissues were obtained from AF patients undergoing cardiac surgery, and immunohistochemical quantification was conducted to assess VCAM-1 expression in these tissues. Univariate analysis and multivariate logistic regression were performed to examine the association between VCAM-1 levels and the risk of atrial fibrillation-related stroke.ResultsA total of 146 patients scheduled for AF ablation and 34 patients scheduled for cardiac surgery were enrolled in this study. Among these two groups, there were 67 cases (45.9%) and 13 cases (38.2%) of AF patients who experienced strokes, respectively. Serum analysis revealed that in the AF group with strokes, the LAA serum VCAM-1 concentration was higher compared to the AF group without strokes (631.64 ± 143.48 pg/ml vs. 336.71 ± 201.66 pg/ml, P < 0.001). Similarly, the PV serum VCAM-1 concentration was higher in the AF group with strokes compared to the group without strokes (591.65 ± 128.23 pg/ml vs. 257.71 ± 157.92 pg/ml, P < 0.001). Additionally, both the AF group with strokes and the group without strokes exhibited higher LAA serum VCAM-1 concentrations compared to PV serum concentrations (631.64 ± 143.48 pg/ml vs. 591.65 ± 128.23 pg/ml, P = 0.041) and (336.71 ± 201.66 pg/ml vs. 257.71 ± 157.92 pg/ml, P = 0.004).Regarding left atrial tissue analysis, the AF group with strokes had a higher average optical density value (AOD) of VCAM-1 compared to the group without strokes (1.257 ± 0.147 vs. 1.093 ± 0.161, P < 0.001), indicating a higher expression level of VCAM-1 in the LAA in the AF group with strokes. In univariate analysis, LAA serum VCAM-1 concentration (OR = 1.15, P < 0.001), PV VCAM-1 concentration (OR = 1.11, P < 0.001), and LAA VCAM-1 AOD value (OR = 3.04, P = 0.021) were all associated with the risk of atrial fibrillation-related stroke. In the multivariate logistic regression analysis, LAA serum VCAM-1 concentration (OR = 1.17, P = 0.002) and PV VCAM-1 concentration (OR = 1.30, P = 0.034) were predictive of atrial fibrillation-related stroke. Specifically, left atrial appendage serum VCAM-1 concentration greater than 387.93 pg/ml and peripheral vein VCAM-1 concentration greater than 344.04 pg/ml were predictive of atrial fibrillation-related strokes.ConclusionsThe risk of stroke in AF is associated with VCAM-1, and elevated serum VCAM-1 concentrations in AF patients who experience strokes may be attributed not only to systemic inflammatory responses but also to increased VCAM-1 expression in LAA tissues. Serum VCAM-1 concentrations in AF patients can serve as predictive factors for atrial fibrillation-related stroke, with LAA serum VCAM-1 concentrations exceeding 387.93 pg/ml and peripheral vein VCAM-1 concentrations exceeding 344.04 pg/ml being predictive of atrial fibrillation-related strokes.

Atrial flutter following ethanol infusion in the vein of Marshall