Left Atrial Remodeling Mechanisms Associated with Atrial Fibrillation

Relationship between left atrium, epicardial fat and severity of atrial fibrillation

To investigate the relationship between left atrium (LA) and epicardial adipose tissue (EAT) parameters and different disease severities (paroxysmal and persistent) in patients with atrial fibrillation (AF). A total of 115 patients with AF (58 paroxysmal and 57 persistent) who underwent cardiac computed tomography angiography (CTA) at our institution between October 2021 and May 2022 were included. The left atrium volume index (LAVI) and left atrium fractal dimension (LAFD) were measured for each patient. EAT volumes and attenuation values for total heart and LA in early and delayed enhancement phases were calculated using semi-automated software. LA and EAT parameters were compared with patients with paroxysmal and persistent AF. Compared with paroxysmal AF, persistent AF had significantly greater LAVI (33.60 ml/m2 vs. 26.65 ml/m2, P < 0.001) and LAFD (1.31 vs. 1.22, P = 0.001). At both early and late enhancement, the total EAT volume (136.29 cm3 vs. 88.68 cm3, 152.30 cm3 vs. 88.96 cm3; all P < 0.001) and attenuation values (-84.00 HU vs. -87.50 HU, -83.00 HU vs. -86.00 HU; all P < 0.05) were significantly higher in persistent AF than in paroxysmal AF. Additionally, LA EAT volumes (15.53 cm3 vs. 8.19 cm3, 18.57 cm3 vs. 9.26 cm3; all P < 0.001) and attenuation values (-74.00 HU vs. -77.00 HU, -75.00 HU vs. -77.00 HU; all P < 0.05) were significantly larger in persistent AF compared with paroxysmal AF, in both early and late enhancement phases. Correlation analysis showed that both LA (r = 0.381, 0.310; P < 0.05) and EAT parameters (r = 0.524, 0.334, 0.665, 0.208, 0.537, 0.223, 0.606, 0.276; P < 0.05) were positively associated with AF severity. Both EAT (volume and attenuation values) and parameters for assessing LA size and morphology, including LAVI and LAFD, were related to the severity of AF.

The Impact of Concomitant Mitral Regurgitation on Echocardiography Parameters After TransCatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis

BACKGROUND

Mitral regurgitation (MR) commonly coexists with aortic stenosis (AS) and is a potential risk factor influencing outcomes following transcatheter aortic valve replacement (TAVR). This meta-analysis aimed to evaluate the mean changes in key echocardiographic parameters before and after TAVR and to compare these changes between patients with moderate-to-severe MR (MR ≥ 2) and those with none-to-mild MR (MR < 2).

METHODS

A comprehensive literature search was conducted using six electronic databases. We included studies that evaluated patients undergoing TAVR, classified them based on baseline MR grade ≥ 2 (moderate/severe MR) or MR grade < 2 (none/mild MR), and reported the mean difference (MD) in echocardiographic parameters before and after TAVR in both groups. The primary outcomes included changes in ejection fraction (EF), LV end-diastolic volume (LVEDV) index, LV end-systolic volume (LVESV) index, LV end-diastolic diameter (LVEDD), LV end-systolic diameter (LVESD), aortic valve area (AVA), and the mean aortic gradient. Pooled MDs were analyzed using a random-effects model.

RESULTS

Thirteen studies with 7163 patients were included, of which 2376 had an MR ≥ 2. The MR < 2 and MR ≥ 2 groups experienced significant improvements in AVA and reductions in mean aortic gradient, LVEDV index, LVESV index, LVEDD, and LVESD. Compared to MR < 2 patients, those with MR ≥ 2 exhibited significantly greater improvements in EF (MD = 2.03; 95% CI: 0.81, 3.24), LVEDV index (MD = -5.55; 95% CI: -7.85, -3.26), LVESV index (MD = -5.43; 95% CI: -7.28, -3.58), LVESD (MD = -2.23; 95% CI: -3.71, -0.26), and mean aortic gradient (MD = 1.43; 95% CI: 0.79, 2.07). However, the changes in LVEDD and AVA were not significantly different between the groups.

CONCLUSIONS

These findings suggest that patients with moderate-to-severe baseline MR before TAVR showed greater pronounced improvements in specific echocardiographic parameters related to LV function and geometry, particularly in LVEF, LVEDV index, LVESV index, and LVESD, compared to those with none-to-mild MR. Future studies should focus on stratifying outcomes according to MR etiology and using advanced imaging techniques to delineate better the mechanisms underlying these improvements.

Predictive model development for left atrial remodeling in hypertrophic cardiomyopathy

Left atrial structural remodeling is closely linked with the prognosis of patients with hypertrophic cardiomyopathy (HCM). This study aimed to evaluate the clinical characteristics and risk factors associated with left atrial remodeling in HCM and to develop an early prediction model. HCM patients who underwent echocardiography during hospitalized enrolled. Patients with a left atrial diastolic anteroposterior diameter ≥ 40 mm were classified as the remodeling group, while others were assigned to the control group. Logistic regression analysis was employed to identify independent predictors, and a nomogram was constructed for prediction. A total of 1554 patients were enrolled, including 442 patients in the remodeling group. Significant differences in clinical and echocardiographic characteristics were observed between the two groups. Multivariate logistic regression analysis identified the following as independent predictors of left atrial remodeling: prothrombin time (P < 0.001; OR 0.863; 95% CI 0.813-0.915), main pulmonary artery diameter (P < 0.001; OR 0.881; 95% CI 0.852-0.911), left ventricular ejection fraction (P < 0.001; OR 1.057; 95% CI 1.043-1.071), and interventricular septal thickness (P < 0.001; OR 0.937; 95% CI 0.916-0.959). A nomogram prediction model based on these factors demonstrated good discriminatory power, with a receiver operating characteristic curve area of 0.7328 (95% CI 0.7052-0.7603). The model's calibration showed high accuracy and consistency with actual outcomes, particularly in intermediate probability ranges. Prothrombin time, main pulmonary artery diameter, left ventricular ejection fraction, and interventricular septal thickness were identified as risk factors for left atrial remodeling in HCM patients. The developed nomogram provides a valuable tool for early risk assessment, aiding in the early detection of left atrial remodeling and facilitating optimized treatment strategies to improve patient prognosis.

Extensive ablation for elderly patients with persistent atrial fibrillation: insights from the EARNEST-PVI prospective randomized trial

BACKGROUND

In patients with persistent atrial fibrillation (AF), extensive ablation for substrate modification, such as linear ablation or complex fractionated atrial electrogram ablation in addition to pulmonary vein isolation (PVI) remains controversial. Previous studies investigating extensive ablation have demonstrated its varying efficacy, suggesting the possible heterogeneity of its efficacy. Aging is a major risk factor for AF and is associated with atrial remodeling. We aimed to compare the efficacy and safety of the extensive ablation strategy compared with PVI alone strategy between young and elderly patients.

METHODS

This study is a post-hoc analysis of the multicenter, randomized controlled, noninferiority trial investigating the efficacy and safety of PVI-only (PVI-alone arm) compared with extensive ablation (PVI-plus arm) in patients with persistent AF (EARNEST-PVI trial). We divided the overall population into 2 groups based on age and assessed treatment effects.

RESULTS

In the young group (age <65 years, N = 206), there was no significant difference in the recurrence rate between the PVI-alone group and PVI-plus group [hazard ratio (HR): 1.00, 95 % CI: 0.57-1.73, p = 0.987], whereas the recurrence rate was significantly lower in the PVI-plus group compared to the PVI-alone group in the elderly group (age ≥65 years, N = 291) (HR: 0.47, 95 % CI: 0.29-0.76, p = 0.0021) (p for interaction = 0.0446). There were no fatal procedural complications.

CONCLUSION

In patients with persistent AF, the extensive ablation strategy was more effective than the PVI-alone strategy in elderly patients, while the effectiveness of both approaches was comparable in young patients.

TRIAL REGISTRATION

URL: https://clinicaltrials.gov; Unique identifier: NCT03514693. URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000022454 Unique ID issued by UMIN: UMIN000019449.

In vivo and in vitro investigations of schisandrin B against angiotensin II induced ferroptosis and atrial fibrosis by regulation of the SIRT1 pathway

Schisandrin B (Sch B) derived from Schisandra chinensis, is known for its anti-inflammatory and anti-microbial properties. The study aimed to explore Sch B's protective roles and underlying mechanisms in angiotensin II (Ang II) - induced ferroptosis, atrial fibrosis, and AF using both in vivo and in vitro models. AF mice model generated induced by Ang II and established an in vitro model using the HL-1 cell line induced by Ang II. We assessed atrial fibrosis through histological analysis and oxidative stress analysis. We employed RT-qPCR and Western blot techniques to evaluate mRNA and protein expression. Sch B significantly attenuated Ang II-induced AF development, atrial apoptosis, and myocardial injury-related molecules, including CK-MB and LDH. Relative DHE intensity, MDA, NOX2, and NOX4 increased significantly, and SOD and CAT levels decreased markedly in Ang II-induced mice. Sch B treatment could inhibit atrial ROS production and oxidative stress in Ang II-infused mice. In addition, Sch B showed cardioprotective effects in Ang II-infused HL-1 cells. Sch B significantly reduced pro-inflammatory cytokines, including IL-1β, TNF-α, and IL-6, restored by EX527 (SIRT1 inhibitor). Sch B inhibited intracellular ROS generation and oxidative stress in HL-1 cells, which were restored by Ex-527. Furthermore, Sch B decreased the increase in Fe2 + concentration caused by Ang II infusion, which was recovered by Ex-527. Sch B markedly increased the expression of SIRT1, SLC7A11, GPX4 and FTH1 while reducing the expression patterns by Ex-527 treatment. Our experimental data suggest that Sch B protects against Ang II-induced ferroptosis, atrial fibrosis, and AF by activating SIRT1 in vivo and in vitro.

Advancing Atrial Fibrillation Research: The Role of Animal Models, Emerging Technologies and Translational Challenges

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia, presenting a significant global healthcare challenge due to its rising incidence, association with increased morbidity and mortality, and economic burden. This arrhythmia is driven by a complex interplay of electrical, structural, and autonomic remodelling, compounded by genetic predisposition, systemic inflammation, and oxidative stress. Despite advances in understanding its pathophysiology, AF management remains suboptimal, with ongoing debates surrounding rhythm control, rate control, and anticoagulation strategies. Animal models have been instrumental in elucidating AF mechanisms, facilitating preclinical research, and advancing therapeutic development. This review critically evaluates the role of animal models in studying AF, emphasizing their utility in exploring electrical, structural, and autonomic remodelling. It highlights the strengths and limitations of various models, from rodents to large animals, in replicating human AF pathophysiology and advancing translational research. Emerging approaches, including optogenetics, advanced imaging, computational modelling, and tissue engineering, are reshaping AF research, bridging the gap between preclinical and clinical applications. We also briefly discuss ethical considerations, the translational challenges of animal studies and future directions, including integrative multi-species approaches, omics technologies and personalized computational models. By addressing these challenges and addressing emerging methodologies, this review underscores the importance of refining experimental models and integrating innovative technologies to improve AF management and outcomes.

Atrial Cardiomyopathy: From Diagnosis to Treatment

With a better understanding of the susceptibility to atrial fibrillation (AF) and the thrombogenicity of the left atrium, the concept of atrial cardiomyopathy (ACM) has emerged. The conventional viewpoint holds that AF-associated hemodynamic disturbances and thrombus formation in the left atrial appendage are the primary causes of cardiogenic embolism events. However, substantial evidence suggests that the relationship between cardiogenic embolism and AF is not so absolute, and that ACM may be an important, underestimated contributor to cardiogenic embolism events. Chronic inflammation, oxidative stress response, lipid accumulation, and fibrosis leading to ACM form the foundation for AF. Furthermore, persistent AF can exacerbate structural and electrical remodeling, as well as mechanical dysfunction of the atria, creating a vicious cycle. To date, the relationship between ACM, AF, and cardiogenic embolism remains unclear. Additionally, many clinicians still lack a comprehensive understanding of the concept of ACM. In this review, we first appraise the definition of ACM and subsequently summarize the noninvasive and feasible diagnostic techniques and criteria for clinical practice. These include imaging modalities such as echocardiography and cardiac magnetic resonance imaging, as well as electrocardiograms, serum biomarkers, and existing practical diagnostic criteria. Finally, we discuss management strategies for ACM, encompassing "upstream therapy" targeting risk factors, identifying and providing appropriate anticoagulation for patients at high risk of stroke/systemic embolism events, and controlling heart rhythm along with potential atrial substrate improvements.

Relationship Between Left Atrial Strain and Atrial Fibrillation: The Role of Stress Echocardiography

Interest in advanced echocardiographic imaging methods is growing. Left atrial strain (LAS) is among recently developed echocardiographic parameters. LAS represents an index of tissue deformation of the left atrium (LA). This parameter is an expression of LA function. Several arrhythmias are caused by impaired LA function. LAS can be assessed with a resting echocardiogram. The evaluation of LAS during stress echocardiography represents another model for assessing LA function. The development of altered LAS during physical or pharmacological stress is a predictor of early LA disease. Our review aims to evaluate the relationship between alterations in LAS and the development of atrial fibrillation (AF), and the diagnostic and prognostic roles of the stress echocardiogram in clinical practice.

Atrial Fibrillation Types and Chronic Kidney Disease are Independent Predictors of Atrial Fibrillation Recurrence After Radiofrequency Ablation

Purpose

Atrial fibrillation (AF) is classified into paroxysmal, persistent, long-term persistent, and permanent types. It is commonly treated by radiofrequency ablation (RFA), which is more successful than conventional anti-arrhythmic drugs, but it is still largely unknown whether these beneficial effects are equally present for all AF types. Here, we evaluated the impact that AF type has on post-RFA patient conditions and identified underlying factors affecting AF prognoses.

Patients and Methods

Three hundred and twenty-nine AF patients who underwent RFA were retrospectively examined (221 paroxysmal, 56 persistent, 52 long-term persistent), during a post-RFA follow-up period, from 3-months to 2-years. Cardiac functional parameters, such as left atrial (LA), ventricular (LV), and pulmonary artery diameters, as well as ejection fraction (EF) and end-diastolic/systolic diameter ratio, were measured using echocardiography. Additionally, chronic kidney disease (CKD) was diagnosed among these AF patients, using the Modification of Diet in Renal Disease (MDRD) formula, and its impact on post-RFA patient outcomes was examined. Logistic regression analysis identified differences between AF and non-AF recurrence groups.

Results

In terms of functional parameters, persistent AF had significantly smaller LA, and larger EF, compared to paroxysmal and long-term persistent groups, while paroxysmal had significantly larger LV versus persistent and long-term persistent after RFA. For post-RFA patient conditions, paroxysmal, compared to persistent and long-term persistent, had significantly lower AF recurrence (18.10% versus 30.36% and 36.54%) and re-hospitalization rates (6.79% versus 14.29% and 19.23%); however, no significant difference was present between the 3 groups in terms of post-operative stroke rates, as well as re-hospitalization duration. Additionally, CKD patients, versus non-CKD, were more prone to AF recurrence and re-hospitalization, being 3.268 times more likely.

Conclusion

AF types and CKD were independent factors influencing AF recurrence, serving as highly sensitive predictors to monitor prognoses and guide treatments. Therefore, personalized treatment regimens should be recommended for different AF patients.

Endothelial activation, Cell-Cell Interactions, and Inflammatory Pathways in Postoperative Atrial Fibrillation Following Cardiac Surgery

BACKGROUND

Postoperative atrial fibrillation (POAF) is common after cardiac surgery and related to endothelial activation and systemic inflammation. Herein, we investigate the pathophysiological mechanisms of AF through endothelial activation and cell-cell interactions related to the development of POAF.

METHODS

Patients without previous AF undergoing cardiac surgery were studied. Permanent AF patients were included as positive controls. Interleukin (IL)-6, Von Willebrand factor (vWF), N-terminal pro-brain natriuretic peptide (NT-proBNP) and high sensitivity troponin T (hsTnT) were evaluated by electrochemiluminescence. Vascular cell adhesion molecule-1 (VCAM-1) and human Growth Differentiation Factor 15 (GDF-15) was assessed by ELISA. Connexins (Cxs) 40 and 43 were measured by tissue immunolabelling, and apoptosis by TUNEL assay.

RESULTS

We included 117 patients (median age 67: 27.8% female): 17 with permanent AF; 27 with POAF and 73 with non- AF. Patients with permanent AF and POAF had higher levels of NT-proBNP, hs-TnT, apoptotic nuclei and decrease Cx43 expression, compared to non-AF patients (all p-value <0.05). VCAM-1 and GDF-15 were significantly higher in permanent AF vs. non-AF (p=0.013 and p=0.035).

CONCLUSIONS

Greater endothelial activation and inflammation in AF patients compared to those without AF was found. The proinflammatory state in AF patients, in addition to the lower expression of Cx43, seems to be associated with atrial remodeling processes occurring in AF.

The incremental value of interatrial septum motion in predicting thrombus or spontaneous echo contrast in patients with non-valvular atrial fibrillation: an observational study on transesophageal echocardiography

Background

The thickness and motion of the Interatrial Septum (IAS) possibly serves as indicators of both structural and functional remodeling of left atrium. This study aims to use transesophageal echocardiography (TEE) to assess IAS motion in non-valvular atrial fibrillation (NVAF) and investigate its correlation with the risk of spontaneous echo contrast (SEC) and thrombus (TH).

Methods

We conducted a cross-sectional study on 318 patients with NVAF who underwent transthoracic echocardiography and TEE. IAS motion was defined as the maximum displacement of IAS observed throughout the cardiac cycles using M-mode TEE.

Results

The prevalence of SEC/TH was 39.9% (127/318) in the overall group. In paroxysmal atrial fibrillation (PAF), the prevalence rate of SEC/TH was 25.3% (47/186), compared to 60.6% (80/132) in persistent atrial fibrillation (PeAF). Multivariable analyses showed that LA volume index (LAVI), mean E/e', S/D ratio, IAS motion and CHA2DS2-VASc scores were significantly associated with SEC/TH. Patients with lower IAS motion showed a higher prevalence of SEC/TH compared to those with higher IAS motion (71.3% vs. 11.6%; P < 0.001). The IAS motion under sinus rhythm could better predict risk of SEC/TH, while the predictive efficacy under AF rhythm was slightly attenuated but still had a high AUC value (0.779). A significant positive correlation was observed between the IAS motion and the LAA filling velocity (PAF r = 0.47; P<0.001 and PeAF r = 0.38; P < 0.001, respectively), LAA emptying velocity (PAF r = 0.55; P < 0.001 and PeAF r = 0.47; P < 0.001, respectively) and LAVI (PAF r = 0.59; P < 0.001 and PeAF r = 0.44; P < 0.001, respectively). The integration of the IAS motion to the CHA2DS2-VASc, LAVI and mean E/e' provided important incremental predictive value of SEC/TH (AUC = 0.859 vs. 0.826, P = 0.02).

Conclusion

IAS motion measured by TEE correlates well with LAA flow velocity and LA size and is independently associated with SEC/TH in NVAF. Additionally, lower IAS motion is associated with a higher prevalence of SEC/TH. Furthermore, the integration of IAS motion to CHA2DS2-VASc, LAVI and mean E/e' can provide additional value for the prediction of SEC/TH.

Fed-CL- an atrial fibrillation prediction system using ECG signals employing federated learning mechanism

Deep learning has shown great promise in predicting Atrial Fibrillation using ECG signals and other vital signs. However, a major hurdle lies in the privacy concerns surrounding these datasets, which often contain sensitive patient information. Balancing accurate AFib prediction with robust user privacy remains a critical challenge to address. We suggest Federated Learning , a privacy-preserving machine learning technique, to address this privacy barrier. Our approach makes use of FL by presenting Fed-CL, a advanced method that combines Long Short-Term Memory networks and Convolutional Neural Networks to accurately predict AFib. In addition, the article explores the importance of analysing mean heart rate variability to differentiate between healthy and abnormal heart rhythms. This combined approach within the proposed system aims to equip healthcare professionals with timely alerts and valuable insights. Ultimately, the goal is to facilitate early detection of AFib risk and enable preventive care for susceptible individuals.

Investigating the Causal Link between Rheumatoid Arthritis and Atrial Fibrillation in East Asian Populations: A Mendelian Randomization Approach

Background

Rheumatoid arthritis (RA) has been associated with atrial fibrillation (AF) in observational studies, yet the causal relationship remains elusive. In this study, we employed Mendelian randomization (MR) to investigate the impact of RA on AF risk specifically in East Asian populations.

Methods

Utilizing genome-wide association study (GWAS) data on RA (n = 212,453) and AF (n = 36,792), we applied the following five MR methods: inverse variance weighted (IVW), MR-RAPS, maximum likelihood, weighted median (WM), and Bayesian weighted Mendelian randomization (BWMR). We evaluated heterogeneity, sensitivity, and pleiotropy.

Results

Five genetic instrumental variants for RA were identified. All MR methods consistently indicated a causal association between RA and AF (IVW: OR = 1.20, 95% CI: 1.01-1.41, p < 0.03; MR-RAPS: OR = 1.21, 95% CI: 1.03-1.42, p < 0.02; maximum likelihood: OR = 1.20, 95% CI: 1.04-1.39, p < 0.01; WM: OR = 1.25, 95% CI: 1.03-1.52, p < 0.03; and BWMR: OR = 1.20, 95% CI: 1.02-1.42, p < 0.03). Sensitivity and pleiotropy analyses confirmed the robustness and validity of the results.

Conclusions

This study establishes a causal link between RA and AF in East Asians. Our results underscore the need for in-depth mechanistic investigations to unravel the underlying pathways. Clinicians should consider AF risk in RA management, emphasizing collaborative care between rheumatologists and cardiologists. Moving forward, future research should explore therapeutic interventions and address the shared biological mechanisms.

Leisure-time physical activity and the incidence of atrial fibrillation in senior adults: a prospective cohort study

OBJECTIVE

Whether physical activity could reduce the risk of atrial fibrillation (AF) remains unclear. This study was to investigate the relationship of leisure-time physical activity (LTPA) with AF incidence among Chinese older adults.

METHODS

A total of 3253 participants aged ≥60 years from the Guangzhou Heart Study were successfully followed between March 2018 and September 2019. LTPA was assessed using a modified Global Physical Activity Questionnaire. AF was ascertained by 12-lead electrocardiograms, 24-hour single-lead Holter and clinical examination. The Cox proportional hazards model was used to the estimate hazard ratio (HR) and 95% confidence interval (CI) after adjustment for confounders, and the population-attributable fraction (PAF) was estimated.

RESULTS

A total of 76 (2.34%) new-onset cases of AF were identified during a median of 31.13 months of follow-up. After adjustment for confounders, subjects who had LTPA at least 10.0 metabolic equivalent (MET)-hours/week had a 55% lower risk of developing AF (HR: 0.45, 95%CI: 0.25-0.81), and at least 20 MET-hours/week reduced the risk by 45% (HR: 0.55, 95%CI: 0.34-0.92). At least 11% (PAF: 11%, 95%CI: 0%-20%) or 14% (PAF: 14%, 95%CI: 0%-26%) of AF cases could be avoided, respectively, if the subjects do LTPA at least 10 MET-hours/week or 20 MET-hours/week. A significant exposure-response trend was also observed between LTPA and AF risk (Plinear-trend = 0.002). For a specific LTPA, doing housework was associated with a 43% reduced risk, while engaging in ball games was associated with an increased risk.

CONCLUSION

This prospective cohort study indicated that a higher LTPA volume was associated with a lower AF risk in Chinese older adults.

A Genomic Link From Heart Failure to Atrial Fibrillation Risk: FOG2 Modulates a TBX5/GATA4-Dependent Atrial Gene Regulatory Network

BACKGROUND

The relationship between heart failure (HF) and atrial fibrillation (AF) is clear, with up to half of patients with HF progressing to AF. The pathophysiological basis of AF in the context of HF is presumed to result from atrial remodeling. Upregulation of the transcription factor FOG2 (friend of GATA2; encoded by ZFPM2) is observed in human ventricles during HF and causes HF in mice.

METHODS

FOG2 expression was assessed in human atria. The effect of adult-specific FOG2 overexpression in the mouse heart was evaluated by whole animal electrophysiology, in vivo organ electrophysiology, cellular electrophysiology, calcium flux, mouse genetic interactions, gene expression, and genomic function, including a novel approach for defining functional transcription factor interactions based on overlapping effects on enhancer noncoding transcription.

RESULTS

FOG2 is significantly upregulated in the human atria during HF. Adult cardiomyocyte-specific FOG2 overexpression in mice caused primary spontaneous AF before the development of HF or atrial remodeling. FOG2 overexpression generated arrhythmia substrate and trigger in cardiomyocytes, including calcium cycling defects. We found that FOG2 repressed atrial gene expression promoted by TBX5. FOG2 bound a subset of GATA4 and TBX5 co-bound genomic locations, defining a shared atrial gene regulatory network. FOG2 repressed TBX5-dependent transcription from a subset of co-bound enhancers, including a conserved enhancer at the Atp2a2 locus. Atrial rhythm abnormalities in mice caused by Tbx5 haploinsufficiency were rescued by Zfpm2 haploinsufficiency.

CONCLUSIONS

Transcriptional changes in the atria observed in human HF directly antagonize the atrial rhythm gene regulatory network, providing a genomic link between HF and AF risk independent of atrial remodeling.

A novel tsRNA-5008a promotes ferroptosis in cardiomyocytes that causes atrial structural remodeling predisposed to atrial fibrillation

Atrial fibrillation (AF) is an extremely common clinical arrhythmia disease, but whether its mechanism is associated with ferroptosis remains unclear. The tRNA-derived small RNAs (tsRNAs) are involved in a variety of cardiovascular diseases, however, their role and mechanism in atrial remodeling in AF have not been studied. We aimed to explore whether tsRNAs mediate ferroptosis in AF progression. The AF models were constructed to detect ferroptosis-related indicators, and Ferrostatin-1 (Fer-1) was introduced to clarify the relationship between ferroptosis and AF. Atrial myocardial tissue was used for small RNA sequencing to screen potential tsRNAs. tsRNA functioned on ferroptosis and AF was explored. Atrial fibrosis and changes in the cellular structures and arrangement were observed in AF mice model, and these alterations were accompanied by ferroptosis occurrence, exhibited by the accumulation of Fe2+ and MDA levels and the decrease of expression of FTH1, GPX4, and SLC7A11. Blocking above ferroptosis activation with Fer-1 resulted in a significant improvement for AF. A total of 7 tsRNAs were upregulated (including tsRNA-5008a) and 2 tsRNAs were downregulated in atrial myocardial tissue in the AF group compared with the sham group. We constructed a tsRNA-mRNA regulated network, which showed tsRNA-5008a targeted 16 ferroptosis-related genes. Knockdown of tsRNA-5008a significantly suppressed ferroptosis through targeting SLC7A11 and diminished myocardial fibrosis both in vitro and in vivo. On the contrary, tsRNA-5008a mimics promoted ferroptosis in cardiomyocytes. Collectively, tsRNA-5008a involved in AF through ferroptosis. Our study provides novel insights into the role of tsRNA-5008a mediated ferroptosis in AF progression.

Beta-blockers in Hypertensive Left Ventricular Hypertrophy and Atrial Fibrillation Prevention

BACKGROUND

Hypertensive left ventricular hypertrophy (HTN LVH) is a key risk factor for atrial fibrillation (AF).

OBJECTIVE

To evaluate the possible role of beta-blockers (BBs) in addition to a renin-angiotensinaldosterone system (RAAS) blocker in AF prevention in patients with HTN LVH.

METHODS

We performed a PubMed, Elsevier, SAGE, Oxford, and Google Scholar search with the search items 'beta blocker hypertension left ventricular hypertrophy patient' from 2013-2023. In the end, a 'snowball search', based on the references of relevant papers as well as from papers that cited them was performed.

RESULTS

HTN LVH is a risk factor for AF. In turn, AF substantially complicates HTN LVH and contributes to the genesis of heart failure (HF) with preserved ejection fraction (HFpEF). The prognosis of HFpEF is comparable with that of HF with reduced EF (HFrEF), and, regardless of the type, HF is associated with five-year mortality of 50-75%. The antiarrhythmic properties of BBs are wellrecognized, and BBs as a class of drugs are - in general - recommended to decrease the incidence of AF in HTN.

CONCLUSION

BBs are recommended (as a class) for AF prevention in several contemporary guidelines for HTN. LVH regression in HTN - used as a single criterion for the choice of antihypertensive medication - does not capture this protective effect. Consequently, it is worth studying how meaningful this antiarrhythmic action (to prevent AF) of BBs is in patients with HTN LVH in addition to a RAAS blocker.

Bidirectional Association Among the Type of Atrial Fibrillation, Sleep-Disordered Breathing Severity, Heart Failure Progression, and Left Atrial Enlargement, in Patients with Atrial Fibrillation

This study aimed to clarify (1) the association among the atrial fibrillation (AF) type, sleep-disordered breathing (SDB), heart failure (HF), and left atrial (LA) enlargement, (2) the independent predictors of LA enlargement, and (3) the effects of ablation on those conditions in patients with AF. The study's endpoint was LA enlargement (LA volume index [LAVI] ≥ 78 mL/m2).Of 423 patients with nonvalvular AF, 236 were enrolled. We evaluated the role of the clinical parameters such as the AF type, SDB severity, and HF in LA enlargement. Among them, 141 patients exhibiting a 3% oxygen desaturation index (ODI) of ≥ 10 events/hour underwent polysomnography to evaluate the SDB severity measured by the apnea-hypopnea index (AHI). The LA enlargement and HF were characterized by the LA diameter/LAVI, an increase in the B-type natriuretic peptide level, and a lower left ventricular ejection fraction.This study showed that non-paroxysmal AF (NPAF) rather than paroxysmal AF (PAF), the SDB severity, LA enlargement, and HF progression had bidirectional associations and exacerbated each other, which generated a vicious cycle that contributed to the LA enlargement. NPAF (OR = 4.55, P < 0.001), an AHI of ≥ 25.10 events/hour (OR = 1.55, P = 0.003), and a 3% ODI of ≥ 15.43 events/hour (OR = 1.52, P = 0.003) were independent predictors of an acceleration of the LA enlargement. AF ablation improved the HF and LA enlargement.To break this vicious cycle, AF ablation may be the basis for suppressing the LA enlargement and HF progression subsequently eliminating the substrates for AF and SDB in patients with AF.

Comparison of left atrial and left atrial appendage mechanics in the recurrence of atrial fibrillation after radiofrequency catheter ablation

OBJECTIVES

Although radiofrequency catheter ablation (RFCA) has become an important treatment strategy for paroxysmal or persistent atrial fibrillation (AF), AF recurrence after RFCA remains an important issue that plagues clinicians and patients. This study aimed to investigate the association of left atrial (LA) and left atrial appendage (LAA) mechanics with AF recurrence after RFCA and to compare their prognostic values in patients with AF undergoing RFCA.

METHODS

A total of 160 patients with non-valvular AF who underwent RFCA for the first time were included in this study. All patients underwent transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) before the procedure. All patients were followed up for one year after RFCA, and AF recurrence was recorded. Speckle-tracking echocardiography was used to measure LA and LAA global longitudinal strain (GLS). LA and LAA mechanical dispersion (MD) were defined as the standard deviation of time to peak strain at each segment standardized by the R-R interval. Logistic regression analysis was used to analyze independent contributors for AF recurrence after RFCA. The prediction efficiency of factors associated with the presence of AF recurrence was evaluated by the receiver operating characteristic (ROC) curve with area under curve (AUC).

RESULTS

During 1-year follow-up, 45 (28%) patients had recurrence, and 115 (72%) patients had no recurrence. The age, CHA2 DS2 -VASc score, NT-proBNP, LA volume index (LAVI), LA MD, and LAA MD of patients in recurrence group were significantly higher than those in no recurrent group (p < .05). The LAA emptying fraction (LAAEF), LA GLS, and LAA GLS in recurrence group were significantly lower than those in no recurrent group (p < .05). Logistic regression analysis showed that LA and LAA GLS were independent contributors for AF recurrence (p < .05), providing incremental values. The AUCs of LA and LAA GLS in predicting AF recurrence were higher than that of other factors, and the LA GLS+LAA GLS joint model had higher prediction efficiency.

CONCLUSION

This study demonstrated the LA and LAA GLS were independent contributors for AF recurrence after RFCA and provided incremental values. LA and LAA GLS can be used as the predictor of AF recurrence after RFCA, and they may be beneficial for the risk stratification of AF recurrence.

The application and mechanism of Chinese medicine in the upstream treatment of atrial fibrillation

Upstream treatment of atrial fibrillation (AF, for short) is a new approach to the prevention and treatment of AF with non-antiarrhythmic drugs, which is essentially primary and secondary prevention of AF. The former refers to the prevention of AF by controlling risk factors such as diabetes, hypertension, and heart failure before AF occurs, and the latter mainly refers to targeting ion channels, inflammation, oxidative stress, and other pathways to reduce or reverse atrial electrical and structural remodeling, reduction of AF load, and reduction of the chance of AF occurrence or progression. More and more studies have shown that many traditional Chinese medicines, active ingredients of Chinese medicines, and Chinese herbal formulas have definite effects on the upstream treatment of AF, but their mechanisms of action are different. Therefore, we summarized the relevant literature on the application and mechanisms of Chinese medicine on the upstream treatment of AF in recent years, hoping to be helpful for subsequent studies.

Obesity and atrial fibrillation: a narrative review from arrhythmogenic mechanisms to clinical significance

The prevalence of obesity and atrial fibrillation (AF), which are inextricably linked, is rapidly increasing worldwide. Obesity rates are higher among patients with AF than healthy individuals. Some epidemiological data indicated that obese patients were more likely to develop AF, but others reported no significant correlation. Obesity-related hypertension, diabetes, and obstructive sleep apnea are all associated with AF. Additionally, increased epicardial fat, systemic inflammation, and oxidative stress caused by obesity can induce atrial enlargement, inflammatory activation, local myocardial fibrosis, and electrical conduction abnormalities, all of which led to AF and promoted its persistence. Weight loss reduced the risk and reversed natural progression of AF, which may be due to its anti-fibrosis and inflammation effect. However, fluctuations in weight offset the benefits of weight loss. Therefore, the importance of steady weight loss urges clinicians to incorporate weight management interventions in the treatment of patients with AF. In this review, we discuss the epidemiology of obesity and AF, summarize the mechanisms by which obesity triggers AF, and explain how weight loss improves the prognosis of AF.

Personalized biomechanical insights in atrial fibrillation: opportunities & challenges

INTRODUCTION

Atrial fibrillation (AF) is an increasingly prevalent and significant worldwide health problem. Manifested as an irregular atrial electrophysiological activation, it is associated with many serious health complications. AF affects the biomechanical function of the heart as contraction follows the electrical activation, subsequently leading to reduced blood flow. The underlying mechanisms behind AF are not fully understood, but it is known that AF is highly correlated with the presence of atrial fibrosis, and with a manifold increase in risk of stroke.

AREAS COVERED

In this review, we focus on biomechanical aspects in atrial fibrillation, current and emerging use of clinical images, and personalized computational models. We also discuss how these can be used to provide patient-specific care.

EXPERT OPINION

Understanding the connection betweenatrial fibrillation and atrial remodeling might lead to valuable understanding of stroke and heart failure pathophysiology. Established and emerging imaging modalities can bring us closer to this understanding, especially with continued advancements in processing accuracy, reproducibility, and clinical relevance of the associated technologies. Computational models of cardiac electromechanics can be used to glean additional insights on the roles of AF and remodeling in heart function.

The Association Between Rheumatoid Arthritis and Atrial Fibrillation: Epidemiology, Pathophysiology and Management

Atrial fibrillation (AF) is the most common cardiac arrhythmia with a significant increase in morbidity and mortality worldwide. Rheumatoid arthritis (RA), as a systemic inflammatory disease, affecting 0.5-1.0% of the adult population, is associated with increased incidence of cardiac arrhythmias such as AF. Several epidemiologic studies find that the risk of AF is increased in RA when compared with the general population. Other studies are inconsistent. Considering that inflammation plays an important role in AF, RA may be involved in the occurrence and development of AF. This review summarizes the epidemiology, pathophysiology, and management of AF in patients with RA.

Feedback attention network for cardiac magnetic resonance imaging super-resolution

BACKGROUND AND OBJECTIVE

Atrial fibrillation (AF) is a common clinical arrhythmia with a high disability and mortality rate. Improving the resolution of atrial structure and its changes in patients with AF is very important for understanding and treating AF.

METHODS

Aiming at the problems of previous deep learning-based image super-resolution (SR) reconstruction methods simply deepening the network, loss of upsampling information, and difficulty in the reconstruction of high-frequency information, we propose the Feedback Attention Network (FBAN) for cardiac magnetic resonance imaging (CMRI) super-resolution. The network comprises a preprocessing module, a multi-scale residual group module, an upsampling module, and a reconstruction module. The preprocessing module uses a convolutional layer to extract shallow features and dilate the number of channels of the feature map. The multi-scale residual group module adds a multi-channel network, a mixed attention mechanism, and a long and short skip connection to expand the receptive field of the feature map, improve the multiplexing of multi-scale features and strengthen the reconstruction of high-frequency information. The upsampling module adopts the sub-pixel method to upsample the feature map to the target image size. The reconstruction module consists of a convolutional layer, which is used to restore the number of channels of the feature map to the original number to obtain the reconstructed high-resolution (HR) image.

RESULTS

Furthermore, the test results on the public dataset of CMRI show that the HR images reconstructed by the FBAN method not only have a good improvement in reconstructed edge and texture information but also have a good improvement in the peak signal-to-noise ratio (PSNR) and the structural similarity index (SSIM) objective evaluation indicators.

CONCLUSION

Compared with the local magnified image, the edge information of the FBAN method reconstructed image has been enhanced, more high-frequency information of the CMRI is restored, the texture details are less lost, and the reconstructed image is less blurry. Overall, the reconstructed image has a lighter feeling of smearing, and the visual experience is more apparent and sharper.

Echocardiographic evaluation of the right atrial size and function: Relevance for clinical practice

Right atrial (RA) structural and functional evaluations have recently emerged as powerful biomarkers for adverse events in various cardiovascular conditions. Quantitative analysis of the right atrium, usually performed with volume changes or speckle-tracking echocardiography (STE), has markedly changed our understanding of RA function and remodeling. Knowledge of reference echocardiographic values and measurement methods of RA volumes and myocardial function is a prerequisite to introduce RA quantitation in the clinical routine. This review describes the methodology, benefits and pitfalls of measuring RA size and function by echocardiography based on the current understanding of right atrial anatomy and physiological function and provides the current knowledge of right atrial function in related cardiac diseases.

The fate of concomitant mild mitral regurgitation in aortic insufficiency: A neglected subject

Objectives

Mitral regurgitation (MR) is commonly experienced by patients with aortic insufficiency (AI), and in its mild form, it is considered benign. However, the progression of concomitant mild regurgitation after the aortic valve surgery (AVS) for AI is poorly characterized. The current study aimed to define the long-term outcomes of MR after surgery and identify the risk factors involved in deterioration.

Methods

Patients presenting with moderate/severe AI and concomitant mild MR (n = 347) between January 2013 and December 2021 were enrolled. MR grade was assessed by transthoracic echocardiography during the follow-up, and deterioration is defined as an increase in grade to moderate or severe MR from the previous follow-up echocardiography. Analysis of risk factors for early mortality, MR deterioration, and long-term mortality was performed.

Results

A total of 278 patients (84.8%) among 328 survivors had at least one follow-up echocardiography, and complete follow-up occurred for 316 patients (96.3%). Mild MR improved to trivial or none in 194 patients (69.8%), progressed to persistent mild MR for 74 patients (26.6%), and deteriorated for 10 patients (3.6%). Preoperative atrial fibrillation [odds ratio (OR), 23.09; 95% confidence interval (CI), 4.35-122.54] and rheumatic AI (OR, 11.61; 95% CI, 1.26-106.85) were shown to be independent risk factors for MR deterioration by generalized linear mixed analysis.

Conclusion

Progression of concomitant mild MR is rare in patients with AI after AVS. However, rheumatic AI and preoperative atrial fibrillation increase the probability of MR deterioration. Careful follow-up for this cohort of patients is recommended.

Neutrophil-Lymphocyte Ratio and Red Blood Cell Distribution Width in Patients with Atrial Fibrillation and Rheumatic Valve Disease

The lifetime risk of developing atrial fibrillation (AF) is 1 in 3 adults, resulting in a prevalence of 2-4%. Rheumatic heart disease (RHD) is a frequent aetiology of valvular heart disease in lowand middle-income countries. Between 21% and 80% of patients with mitral valve disease, especially with stenosis, may have AF. Both these conditions, AF and RHD, present a state of persistent inflammation. In turn, inflammation is a frequent cause of anisocytosis, which can be evidenced through the parameter RDW (red bold cell distribution width). Factors associated with increased RDW are also known as risk factors associated with a higher incidence of AF. RDW may have an independent role in the pathogenesis of AF and the increased propensity of both thromboembolic and bleeding events. Another marker involved in the incidence of AF is the neutrophil-lymphocyte ratio. This is also a marker of oxidative stress and inflammation and is associated with a higher rate of AF recurrence. This review will evaluate these biomarkers and their association with cardiovascular events in patients with AF and RHD. The hypotheses and current debates about the relationship of biomarkers with the severity of chronic valve dysfunction, with acute rheumatic carditis in the paediatric population, and with the presence of thrombus in the left atrium will be discussed.

SegNet-based left ventricular MRI segmentation for the diagnosis of cardiac hypertrophy and myocardial infarction

OBJECTIVE

A set of cardiac MRI short-axis image dataset is constructed, and an automatic segmentation based on an improved SegNet model is developed to evaluate its performance based on deep learning techniques.

METHODS

The Affiliated Hospital of Qingdao University collected 1354 cardiac MRI between 2019 and 2022, and the dataset was divided into four categories: for the diagnosis of cardiac hypertrophy and myocardial infraction and normal control group by manual annotation to establish a cardiac MRI library. On the basis, the training set, validation set and test set were separated. SegNet is a classical deep learning segmentation network, which borrows part of the classical convolutional neural network, that pixelates the region of an object in an image division of levels. Its implementation consists of a convolutional neural network. Aiming at the problems of low accuracy and poor generalization ability of current deep learning frameworks in medical image segmentation, this paper proposes a semantic segmentation method based on deep separable convolutional network to improve the SegNet model, and trains the data set. Tensorflow framework was used to train the model and the experiment detection achieves good results.

RESULTS

In the validation experiment, the sensitivity and specificity of the improved SegNet model in the segmentation of left ventricular MRI were 0.889, 0.965, Dice coefficient was 0.878, Jaccard coefficient was 0.955, and Hausdorff distance was 10.163 mm, showing good segmentation effect.

CONCLUSION

The segmentation accuracy of the deep learning model developed in this paper can meet the requirements of most clinical medicine applications, and provides technical support for left ventricular identification in cardiac MRI.

DE-MRI myocardial fibrosis segmentation and classification model based on multi-scale self-supervision and transformer

OBJECTIVE

The segmentation and categorization of fibrotic tissue in time-lapse enhanced MRI scanning are quite challenging, and it is mainly done manually for myocardial DE-MRI images. On the other hand, DE-MRI instructions for segmenting and classifying cardiac hypertrophy are complex and prone to inaccuracy. Developing cardiac DE-MRI classification and prediction methods is crucial.

METHODS

This paper introduces a self-supervised myocardial histology segmentation algorithm with multi-scale portrayal consistency to address the degree of sophistication of cardiology DE-MRI. The model retrieves multi-scale representations from multiple expanded viewpoints using a Siamese system and uses resemblance learning instruction to achieve unlabeled representations. The DE-MRI data train the network weights to generate a superior segmentation effect by accurately reflecting the exact scale information. The paper provides an end-to-end method for detecting myocardial fibrosis tissue using a Transformer as a result of the poor classification outcomes of myocardial fibrosis substance in DE-MRI. A deep learning model is created using the Pre-LN Transformer decoded simultaneously with the Multi-Scale Transformer backbone structure developed in this paper. In addition, the joint regression cost, which incorporates the CIoU Loss and the L1 Loss, is used to determine the distance between forecast blocks and labels.

RESULTS

Increasing the independent evaluation and annotations position compared enhances performance compared to the segmentation method without canvas matching by 1.76%, 1.27%, 0.93%, and -1.17 mm on Dice, PPV, SEN, and HD, respectively. Based on the strongest of the three single-scale representation methodologies, the segmentation model in this study is enhanced by 0.71%, 0.79%, and 1.47%, as well as -1.49 mm on Dice, PPV, SEN, and HD, respectively. The effectiveness and reliability of the segmentation model are confirmed. Additionally, testing results show that this study's recognition system's mAP is 84.97%, which is greater than the benchmark techniques used in most other studies. The framework converges round is compressed by 18.1% compared to the DETR detection approach, and the identification rate is improved by 3.5%, proving the strategy's value.

CONCLUSION

The self-supervised cardiac fibrosis segmentation method with multi-scale portrayal consistency and end-to-end myocardial histology categorization is introduced in this study. To solve the challenges of segmentation and myocardial fibrosis identification in cardiology DE-MRI, a Transformer-based detection approach is put forth. It may address the issue of the myocardial scarring material's low accuracy in segmentation and classification in DE-MRI, as well as provide clinicians with a fibrosis diagnosis that is supplementary to the conventional therapy of heart ailments.

ASSOCIATION OF LEFT ATRIAL SPONTANEOUS ECHO CONTRAST WITH CLINICAL AND HEMODYNAMIC CHARACTERISTICS OF PATIENTS WITH LONG-TERM EPISODES OF PERSISTENT ATRIAL FIBRILLATION

OBJECTIVE

The aim: To identify clinical and hemodynamic factors, associated with left atrial spontaneous echo contrast (LASEC) (LASEC in general, and the dense LASEC), in non-valvular persistent atrial fibrillation (AF) patients with the duration of AF episode ≥90 days.

PATIENTS AND METHODS

Materials and methods: The cross-sectional study consecutively enrolled 115 persistent AF patients with the duration of its episode ≥90 days (82 (71,3 %) males; mean age 59 ± 11 years). Transthoracic (TEE) and transesophageal echocardiography (TEE) were performed. LASEC (by TEE) was observed in 79 (68,7 %) patients. The dense (moder¬ate-to-severe) LASEC was detected in 23 (20,0 %) cases.

RESULTS

Results: Heart failure (HF) stage C (OR 2,09 (95 % CI 1,24-3,53); p=0,006), lower TEE-derived left atrial appendage (LAA) flow velocity (FV) (OR 0,94 (95 % CI 0,91-0,98); p=0,003), and the presence of TTE-derived pulmonary hypertension (PH), appeared to be strongly associated with LASEC (AUC for logistic regression model: 0,83 [95 % СI 0,75- 0,89]). The presence of diabetes mellitus type 2 (DM) (OR 2,34 (95 % CI 1,13-4,86); p=0,027), along with lower LAA FV (OR 0,83 (95 % CI 0,76-0,91); p<0,001), were strongly associated with dense LASEC (AUC: 0,89 [95 % CI 0,82-0,94]).

CONCLUSION

Conclusions: The TEE-derived LASEC in patients with long term episodes (≥90 days) of persistent AF was strongly associated with HF stage C and TTE-derived PH, and with lower TEE-derived LAA FV. The presence of DM, in addition to lower LAA FV, was related to dense LASEC.

Atrial fibrillation: Insights from animal models, computational modeling, and clinical studies

Atrial fibrillation (AF) is the most common human arrhythmia, affecting millions of patients worldwide. A combination of risk factors and comorbidities results in complex atrial remodeling, which increases AF vulnerability and persistence. Insights from animal models, clinical studies, and computational modeling have advanced the understanding of the mechanisms and pathophysiology of AF. Areas of heterogeneous pathological remodeling, as well as altered electrophysiological properties, serve as a substrate for AF drivers and spontaneous activations. The complex and individualized presentation of this arrhythmia suggests that mechanisms-based personalized approaches will likely be needed to overcome current challenges in AF management. In this paper, we review the insights on the mechanisms of AF obtained from animal models and clinical studies and how computational models integrate this knowledge to advance AF clinical management. We also assess the challenges that need to be overcome to implement these mechanistic models in clinical practice.

Nano drugs delivery system: A novel promise for the treatment of atrial fibrillation

Atrial fibrillation (AF) is one of the most common sustained tachyarrhythmias worldwide, and its prevalence is positively correlated with aging. AF not only significantly reduces the quality of life of patients but also causes a series of complications, such as thromboembolism, stroke, and heart failure, increases the average number of hospitalizations of patients, and places a huge economic burden on patients and society. Traditional drug therapy and ablation have unsatisfactory success rates, high recurrence rates, and the risk of serious complications. Surgical treatment is highly traumatic. The nano drug delivery system has unique physical and chemical properties, and in the application of AF treatment, whether it is used to assist in enhancing the ablation effect or for targeted therapy, it provides a safer, more effective and more economical treatment strategy.

PAGln, an Atrial Fibrillation-Linked Gut Microbial Metabolite, Acts as a Promoter of Atrial Myocyte Injury

Phenylacetylglutamine (PAGln), a gut microbiota (GM)-derived metabolite, is associated with cardiovascular disease. Studies have shown that disordered GM participated in the progression of atrial fibrillation (AF), but the relationship between PAGln and AF is unclear. This study investigated the characteristics of PAGln in AF patients and its impact on atrial myocytes. Based on our previous metagenomic data, the relative abundance of porA, a critical bacterial enzyme for PAGln synthesis, exhibited an increased tendency in AF. In an independent cohort consisting of 42 controls without AF and 92 AF patients, plasma PAGln levels were higher in AF patients than in controls (p < 0.001) by immunoassay. Notably, PAGln exerted a predictive potential of AF with an AUC of 0.774 (p < 0.001), and a predictive model constructed based on the PAGln and Taiwan AF score further improved the predictive potential. Furthermore, a positive correlation was determined between PAGln and LA diameter. Subsequently, the effect of PAGln intervention was examined on HL-1 cells in vitro, revealing that PAGln increased apoptosis, reactive oxygen species (ROS) production, CaMKII and RyR2 activation and decreased cell viability. In conclusion, increased PAGln was associated with AF, and PAGln might contribute to the AF pathogenesis by promoting oxidative stress and apoptosis in atrial myocytes.

Association Between TCF21 Gene Polymorphism with the Incidence of Paroxysmal Atrial Fibrillation and the Efficacy of Radiofrequency Ablation for Patients with Paroxysmal Atrial Fibrillation

Purpose

Atrial fibrillation (AF) is the most common sustained arrhythmia with a high rate of recurrence after catheter ablation. The gene encoding transcription factor 21 (TCF21) has been linked to coronary artery disease risk by human genome-wide association studies in multiple racial ethnic groups. However, the association of TCF21 with AF remains unclear.

Patients and Methods

Circulating leukocytes in patients with paroxysmal AF (PAF) and 92 age-matched controls without a history of cardiovascular disease, AF and other arrhythmias were collected. A total of 224 PAF patients receiving radiofrequency ablation had an 18-month scheduled follow-up study for recurrence of AF. Three single-nucleotide polymorphisms (SNPs) of TCF21 (rs2327429, rs2327433 and rs12190287) were genotyped by PCR, and serum levels of TCF21 were measured by ELISA.

Results

More males and smokers were observed in the PAF group compared with controls. C allele of rs2327429, G allele and GG genotype of rs12190287 were markedly associated with the increased onset of PAF. The levels of serum TCF21 were significantly higher in PAF group than those in control group (1.96 ± 0.85 vs 0.86 ± 0.49 ng/mL, P<0.001). Based on logistic regression analysis, we confirmed that risk allele at rs12190287 and serum TCF21 concentration were independently correlated with the incidence of PAF. Furthermore, GG genotype of rs12190287 enhanced the susceptibility of AF recurrence after ablation.

Conclusion

G allele and GG genotype of rs12190287 in TCF21 and elevated TCF21 concentration are significantly associated with the onset of PAF and recurrence after ablation.

Left atrial-left ventricular angle, a new measure of left atrial and left ventricular remodeling

We assessed the left atrial-left ventricular (LA-LV) long axis angulation value as a new measure of LA remodeling, and studied its predictors, its effect on two-dimensional LA volume (2D LAVol) estimation, and optimization techniques for 2D LAVol values. Retrospective electrocardiogram-gated coronary computed tomographic angiograms of 164 consecutive patients were reviewed. The LA–LV angle was measured in reconstructed 3-chamber views, and its predictors were determined. The LAVol measured by the area-length method after image optimization along the LV long axis (AL) and the LA long axis (AC–AL), was compared with that measured by the three-dimensional (3D)-volumetric method. LAVol calculation was modified to minimize differences from the 3D values. LA–LV angles ranged from 0° to 63°. In the univariate analysis, decreasing angulation was significantly associated with increasing LV end-diastolic volume (LVEDV), mitral regurgitation grade, LV and LA anteroposterior dimensions, and decreasing LV ejection fraction (LVEF). On multivariate analysis, increasing LVEDV, MR, and LA anteroposterior dimension inversely correlated with angulation; LVEF was positively correlated. The AL and 3D methods significantly differed only for patients with angles ≤ 29.9°. Conversely, LAVol was overestimated for all angules by AC–AL. Modification of AL LAVol using a regression equation, or by substituting the shortest with the longest and average LA lengths in patients with angles ≤ 29.9° and 30–39.9°, respectively neutralized the difference. The LA–LV angle is a new measure of LA and LV remodeling predicted by LV size and function, MR, and LA-anteroposterior dimension. AL formula modifications based on angulation in LV-optimized views better correlate with the 3D method than LA-view modification.