High prevalence of atrial fibrosis in patients with dilated cardiomyopathy

Left atrial cardiomyopathy: Pathophysiological insights, assessment methods and clinical implications

Atrial cardiomyopathy is defined as any complex of structural, architectural, contractile or electrophysiological changes affecting atria, with the potential to produce clinically relevant manifestations. Most of our knowledge about the mechanistic aspects of atrial cardiomyopathy is derived from studies investigating animal models of atrial fibrillation and atrial tissue samples obtained from individuals who have a history of atrial fibrillation. Several noninvasive tools have been reported to characterize atrial cardiomyopathy in patients, which may be relevant for predicting the risk of incident atrial fibrillation and its related outcomes, such as stroke. Here, we provide an overview of the pathophysiological mechanisms involved in atrial cardiomyopathy, and discuss the complex interplay of these mechanisms, including aging, left atrial pressure overload, metabolic disorders and genetic factors. We discuss clinical tools currently available to characterize atrial cardiomyopathy, including electrocardiograms, cardiac imaging and serum biomarkers. Finally, we discuss the clinical impact of atrial cardiomyopathy, and its potential role for predicting atrial fibrillation, stroke, heart failure and dementia. Overall, this review aims to highlight the critical need for a clinically relevant definition of atrial cardiomyopathy to improve treatment strategies.

Association between left atrial myopathy and sarcomere mutation in patients with hypertrophic cardiomyopathy: insights into left atrial strain by MRI feature tracking

OBJECTIVES

Left atrial (LA) myopathy, characterized by LA enlargement and mechanical dysfunction, is associated with worse prognosis in hypertrophic cardiomyopathy (HCM) while the impact of sarcomere mutation on LA myopathy remains unclear. We aimed to assess the association between LA myopathy and sarcomere mutation and to explore the incremental utility of LA strain in mutation prediction.

METHODS

A total of 105 consecutive HCM patients (mean age 47.8 ± 11.9 years, 71% male) who underwent HCM-related gene screening and cardiac MRI were retrospectively enrolled. LA volume, ejection fraction and strain indices in reservoir, conduit, and booster-pump phases were investigated respectively.

RESULTS

Fifty mutation-positive patients showed higher LA maximal volume index (59.4 ± 28.2 vs 43.8 ± 18.1 mL/m2, p = 0.001), lower reservoir (21.3 ± 7.9 vs 26.2 ± 6.6%, p < 0.001), and booster-pump strain (12.1 ± 5.4 vs 17.1 ± 5.0%, p < 0.001) but similar conduit strain (9.2 ± 4.5 vs 9.1 ± 4.5%, p = 0.909) compared with mutation-negative patients. In multivariate logistic regression, LA booster-pump strain was associated with sarcomere mutation (odds ratio = 0.86, 95% confidence interval: 0.77-0.96, p = 0.010) independent of maximal wall thickness, late gadolinium enhancement, and LA volume. Furthermore, LA booster-pump strain showed incremental value for mutation prediction added to Mayo II score (AUC 0.798 vs 0.709, p = 0.024).

CONCLUSIONS

In HCM, mutation-positive patients suffered worse LA enlargement and worse reservoir and booster-pump functions. LA booster-pump strain was a strong factor for sarcomere mutation prediction added to Mayo II score.

CLINICAL RELEVANCE STATEMENT

The independent association between sarcomere mutation and left atrial mechanical dysfunction provide new insights into the pathogenesis of atrial myopathy and is helpful to understand the adverse prognosis regarding atrial fibrillation and stroke in mutation-positive patients.

KEY POINTS

• In patients with hypertrophic cardiomyopathy, left atrial (LA) reservoir and booster-pump function, but not conduit function, were significantly impaired in mutation-positive patients compared with mutation-negative patients. • LA booster-pump strain measured by MRI-derived feature tracking is feasible to predict sarcomere mutation with high incremental value added to Mayo II score.

Atrial Myopathy Quantified by Speckle-tracking Echocardiography in Mice

BACKGROUND

Emerging evidence suggests that atrial myopathy may be the underlying pathophysiology that explains adverse cardiovascular outcomes in heart failure (HF) and atrial fibrillation. Lower left atrial (LA) function (strain) is a key biomarker of atrial myopathy, but murine LA strain has not been described, thus limiting translational investigation. Therefore, the objective of this study was to characterize LA function by speckle-tracking echocardiography in mouse models of atrial myopathy.

METHODS

We used 3 models of atrial myopathy in wild-type male and female C57Bl6/J mice: (1) aged 16 to 17 months, (2) Ang II (angiotensin II) infusion, and (3) high-fat diet+Nω-nitro-L-arginine methyl ester (HF with preserved ejection fraction, HFpEF). LA reservoir, conduit, and contractile strain were measured using speckle-tracking echocardiography from a modified parasternal long-axis window. Left ventricular systolic and diastolic function, and global longitudinal strain were also measured. Transesophageal rapid atrial pacing was used to induce atrial fibrillation.

RESULTS

LA reservoir, conduit, and contractile strain were significantly reduced in aged, Ang II and HFpEF mice compared with young controls. There were no sex-based interactions. Left ventricular diastolic function and global longitudinal strain were lower in aged, Ang II and HFpEF, but left ventricular ejection fraction was unchanged. Atrial fibrillation inducibility was low in young mice (5%), moderately higher in aged mice (20%), and high in Ang II (75%) and HFpEF (83%) mice.

CONCLUSIONS

Using speckle-tracking echocardiography, we observed reduced LA function in established mouse models of atrial myopathy with concurrent atrial fibrillation inducibility, thus providing the field with a timely and clinically relevant platform for understanding the pathophysiology and discovery of novel treatment targets for atrial myopathy.

Catheter ablation of atrial fibrillation in patients with and without hypertrophic cardiomyopathy: systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM). There is limited data regarding the outcomes of AF catheter ablation in HCM patients. In this study, we aimed to synthesize all available evidence on the effectiveness of ablation of AF in patients with HCM compared to those without HCM.

METHODS AND RESULTS

We systematically reviewed bibliographic databases to identify studies published through February 2023. We included cohort studies with available quantitative information on rates of recurrent atrial arrhythmias, anti-arrhythmic drug (AAD) therapy, and repeat ablation procedures after initial AF ablation in patients with vs without HCM. Estimates were combined using random-effects meta-analysis models and reported as risk ratios (RR) and 95% confidence intervals (CI). Eight studies were included in quantitative synthesis (262 HCM and 642 non-HCM patients). During median follow-up 13-54 months across studies, AF recurrence rates ranged from 13.3% to 92.9% in HCM and 7.6% to 58.8% in non-HCM patients. The pooled RR for recurrent atrial arrhythmia after the first AF ablation in HCM patients compared to non-HCM controls was 1.498 (95% CI = 1.305-1.720; P < 0.001). During follow-up, HCM patients more often required AAD therapy (RR = 2.844; 95% CI = 1.713-4.856; P < 0.001) and repeat AF ablation (RR = 1.544; 95% CI = 1.070-2.228; P = 0.02). The pooled RR for recurrent atrial arrhythmias after the last AF ablation was higher in patients with HCM than those without HCM (RR = 1.607; 95% CI = 1.235-2.090; P < 0.001).

CONCLUSIONS

Compared to non-HCM patients, those with HCM had higher rates of recurrent atrial arrhythmias, AAD use, and need for repeat AF ablation after initial ablation of AF.

A Case of Non-Tachycardic Atrial Fibrillation Whose Left Ventricular Systolic Dysfunction Improved After Catheter Ablation

It is difficult to identify the causes and optimal treatment of heart failure (HF) in patients with atrial fibrillation (AF) and HF with reduced ejection fraction (EF) (HFrEF). Tachyarrhythmia can cause left ventricular (LV) systolic dysfunction called tachycardia-induced cardiomyopathy (TIC). In patients with TIC, conversion to sinus rhythm may lead to improvement in LV systolic dysfunction. However, it is unclear whether we should try to convert patients with AF without tachycardia to sinus rhythm. A 46-year-old man with chronic AF and HFrEF came to our hospital. His New York Heart Association (NYHA) classification was class II. The blood test showed a brain natriuretic peptide of 105 pg/mL. Electrocardiogram (ECG) and 24-h ECG showed AF without tachycardia. Transthoracic echocardiography (TTE) showed left atrial (LA) dilatation, LV dilatation, and diffuse LV hypokinesis (EF was 40%). Although he was optimized medically, NYHA classification II persisted. Therefore, he underwent direct current cardioversion and catheter ablation. After his AF converted to a sinus rhythm of heart rate (HR) 60 - 70 beats per minute (bpm), TTE showed improvement in LV systolic dysfunction. We gradually reduced oral medications for arrhythmia and HF. We subsequently succeeded in discontinuing all medications 1 year after catheter ablation. TTE performed between 1 and 2 years after catheter ablation showed normal LV function and normal cardiac size. During the 3 years of follow-up, there was no recurrence of AF, and he was not readmitted to the hospital. This patient showed the effectiveness of converting AF to sinus rhythm in patients without tachycardia.

Difference in left atrial myocardial dynamics during reservoir phase between hypertrophic cardiomyopathy and hypertensive heart determined using three-dimensional speckle tracking echocardiography

We aimed to investigate left atrial (LA) myocardial dynamics during reservoir phase using three-dimensional speckle-tracking echocardiography (3DSTE) focusing on its longitudinal-circumferential relationship in patients with left ventricular (LV) hypertrophy and clarifying the difference in LA myocardial reservoir dynamics between hypertrophic cardiomyopathy (HCM) and hypertension with LV hypertrophy (HT-LVH). We studied 4 age-matched groups consisting of 27 patients with HCM, 16 with HT-LVH, 22 hypertensive patients without LV hypertrophy (HT), and 18 normal controls. Using 3DSTE, we measured LA global longitudinal strain (LA-LSR), global circumferential strain (LA-CSR), and global area strain (LA-ASR) during the reservoir phase, as well as LV global longitudinal strain (LV-LS), global circumferential strain (LV-CS), and global area strain (LV-AS). LA-LSR was significantly lower in the HCM and HT-LVH groups than in the controls, but there was no significant difference between the HCM and HT-LVH groups. LA-CSR and LA-ASR were significantly lower in the HCM group than in the other three groups, among which no significant difference was detected. In all subjects, LA-LSR was significantly correlated with LV-LS but not with LV-CS. LA-CSR was correlated with neither LV-LS nor LV-CS. In conclusion, both longitudinal and circumferential LA myocardial expansion during reservoir phase were reduced in HCM, while only the longitudinal one was reduced in HT-LVH. Reduction of LA circumferential expansion may reflect a more serious and intrinsic impairment of LA myocardial distensibility in HCM. Measuring LA-CSR and LA-ASR using 3DSTE would contribute to a more accurate understanding of LA reservoir function abnormality in HCM.

The Added Value of Atrial Strain Assessment in Clinical Practice

Speckle tracking echocardiography has emerged as a sensitive tool to analyze myocardial function with improved diagnostic accuracy and prognostic value. Left atrial strain assessment has become a novel imaging method in cardiology with superior prognostic value compared to conventional left atrial volume indices. Left atrial function is divided into three phases, reservoir function being the most important. This review summarizes the added value of speckle tracking echocardiography derived left atrial strain assessment in clinical practice. Recently published data suggest the prognostic value of left atrial reservoir function in heart failure, atrial fibrillation, stroke and valvular heart disease. Furthermore, left atrial reservoir strain proved to be a predictor of cardiovascular morbidity and mortality in the general population. Thus, routine assessment of left atrial function can be an optimal strategy to improve cardiovascular risk prediction and supplement the current risk prediction models.

Emerging Antiarrhythmic Drugs for Atrial Fibrillation

Atrial fibrillation (AF), the most common cardiac arrhythmia worldwide, is driven by complex mechanisms that differ between subgroups of patients. This complexity is apparent from the different forms in which AF presents itself (post-operative, paroxysmal and persistent), each with heterogeneous patterns and variable progression. Our current understanding of the mechanisms responsible for initiation, maintenance and progression of the different forms of AF has increased significantly in recent years. Nevertheless, antiarrhythmic drugs for the management of AF have not been developed based on the underlying arrhythmia mechanisms and none of the currently used drugs were specifically developed to target AF. With the increased knowledge on the mechanisms underlying different forms of AF, new opportunities for developing more effective and safer AF therapies are emerging. In this review, we provide an overview of potential novel antiarrhythmic approaches based on the underlying mechanisms of AF, focusing both on the development of novel antiarrhythmic agents and on the possibility of repurposing already marketed drugs. In addition, we discuss the opportunity of targeting some of the key players involved in the underlying AF mechanisms, such as ryanodine receptor type-2 (RyR2) channels and atrial-selective K⁺-currents (I_K2P and I_SK) for antiarrhythmic therapy. In addition, we highlight the opportunities for targeting components of inflammatory signaling (e.g., the NLRP3-inflammasome) and upstream mechanisms targeting fibroblast function to prevent structural remodeling and progression of AF. Finally, we critically appraise emerging antiarrhythmic drug principles and future directions for antiarrhythmic drug development, as well as their potential for improving AF management.

Regional Diversities in Fibrogenesis Weighed as a Key Determinant for Atrial Arrhythmogenesis

Atrial fibrosis plays a key role in atrial myopathy, resulting in the genesis of atrial fibrillation (AF). The abnormal distribution of fibrotic tissue, electrical coupling, paracrine interactions, and biomechanical–electrical interactions have all been suggested as causes of fibrosis-related arrhythmogenesis. Moreover, the regional difference in fibrogenesis, specifically the left atrium (LA) exhibiting a higher arrhythmogenesis and level of fibrosis than the right atrium (RA) in AF, is a key contributor to atrial arrhythmogenesis. LA fibroblasts have greater profibrotic cellular activities than RA fibroblasts, but knowledge about the regional diversity of atrial regional fibrogenesis remains limited. This article provides a comprehensive review of research findings on the association between fibrogenesis and arrhythmogenesis from laboratory to clinical evidence and updates the current understanding of the potential mechanism underlying the difference in fibrogenesis between the LA and RA.

Left atrial reverse remodeling predicts long-term survival after cardiac resynchronization therapy

BACKGROUND

Left ventricular (LV) reverse remodeling has been identified as a strong predictor of long-term survival in patients receiving CRT. Interestingly, CRT induces reverse remodeling in the left atrium (LA) as well. It is currently unknown to what extent LA reverse remodeling is correlated to long-term survival after CRT. This study aims to assess the long-term prognostic value of left atrium (LA) reverse remodeling in patients undergoing cardiac resynchronization therapy (CRT).

METHODS

Baseline and 3-months follow-up echocardiograms after CRT implantation were prospectively assessed to determine changes in left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), left atrial volume (LAV), and left atrial reservoir strain (LAS_r). Multivariate Cox regression analysis was performed to identify predictors for long-term survival.

RESULTS

In our study population of 99 patients with a mean follow-up of 6.3 ± 2.1 years, 43 patients (43%) reached the end-point of all-cause mortality. More extensive LA reverse remodeling, as measured by a relative increase in LAS_r, was observed in survivors compared to non-survivors (43 [29-64] % vs. 8 [2-28] %, P < 0.001, respectively). After multivariate analysis, delta LAS_r remained the only significant predictor of mortality [HR per 5%: 0.90 (0.86-0.95); AUC 0.78 (0.68-0.88)].

CONCLUSION

An increase in LAS_r is associated with favorable long-term outcome after CRT. The observed clinical importance of LA reverse remodeling after CRT asks for further validation in larger prospective cohorts.

Left Atrial Function Predicts Outcome in Dilated Cardiomyopathy: Fast Long-Axis Strain Analysis Derived from MRI

Background There is increasing recognition that left atrial (LA) function is prognostically important in cardiovascular disease. LA strain is a sensitive parameter to describe complex LA phasic function. However, the prognostic value of LA strain in participants with idiopathic dilated cardiomyopathy (DCM) remains unclear. Purpose To evaluate the prognostic value of LA strain derived from cardiac MRI in study participants with idiopathic DCM. Materials and Methods Participants with idiopathic DCM who underwent cardiac MRI between June 2012 and November 2018 were prospectively enrolled. The fast long-axis strain MRI method was performed to assess LA strain. The primary end point was all-cause mortality and heart transplant, and the secondary end point was a combination of primary end point, heart failure readmission, and aborted sudden cardiac death. Cox regression analyses and Kaplan-Meier survival analysis were performed to identify the association between variables and outcomes. Results There were 497 participants (mean age, 47 years ± 14 [standard deviation]; 357 men) evaluated. During a median follow-up of 36 months (interquartile range, 26-54 months), 113 participants reached primary end points and 203 participants reached secondary end points. LA reservoir, conduit and booster strain, and strain rate were lower in participants with primary end points (P < .001). In multivariable Cox regression analysis, LA reservoir strain and conduit strain were independent predictors for primary end point (hazard ratio [HR] per 1% increase, 0.95 [95% CI: 0.91, 0.99; P = .008] and 0.92 [95% CI: 0.87, 0.98; P = .010], respectively) and secondary end points (HR per 1% increase, 0.95 [95% CI: 0.93, 0.97; P < .001] and 0.93 [95% CI: 0.89, 0.97; P < .001], respectively). In addition, LA reservoir strain and conduit strain added incremental prognostic value to clinical risk factors and late gadolinium enhancement presence (all, P < .05). Conclusion Left atrial reservoir and conduit strain, derived from cardiac MRI by using the fast long-axis method, were independent predictors of adverse clinical outcomes in idiopathic dilated cardiomyopathy. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Ambale-Venkatesh in this issue.

The Relationship Between Cardio-Ankle Vascular Index and Left Atrial Phasic Function in Hypertensive Patients With Preserved Ejection Fraction

Background: To investigate the relationship between arterial stiffness, reflected by cardio-ankle vascular index (CAVI) value, and left atrial (LA) phasic function in hypertensive patients with preserved left ventricular ejection fraction (LVEF).

Methods: We retrospectively studied 165 consecutive patients (mean age, 66.5 ± 11.7 years) diagnosed with hypertension with preserved LVEF who had undergone CAVI measurement and echocardiography on the same day. The latter included speckle-tracking echocardiography to assess LA phasic function (reservoir, conduit, and pump strain) and left ventricular global longitudinal strain (LVGLS).

Results: The results of univariate analysis showed CAVI value to be correlated with LA reservoir strain and LA conduit strain (r = −0.387 and −0.448, respectively; both P < 0.0001). The results of multiple linear regression analysis showed CAVI value to be independently related to age (β = 0.241, P = 0.002) and LA conduit strain (β = −0.386, P = 0.021) but not LV mass index, LA volume index, or LV systolic function (including LVGLS).

Conclusion: In hypertensive patients with preserved LVEF, increased CAVI value appears to be independently associated with impaired LA phasic function (particularly LA conduit function) before LA and LV remodeling. CAVI determination to assess arterial stiffness may be useful in the early detection of interactions between cardiovascular abnormalities in hypertensive patients.

Calcium Regulation on the Atrial Regional Difference of Collagen Production Activity in Atrial Fibrogenesis

Background: Atrial fibrosis plays an important role in the genesis of heart failure and atrial fibrillation. The left atrium (LA) exhibits a higher level of fibrosis than the right atrium (RA) in heart failure and atrial arrhythmia. However, the mechanism for the high fibrogenic potential of the LA fibroblasts remains unclear. Calcium (Ca²⁺) signaling contributes to the pro-fibrotic activities of fibroblasts. This study investigated whether differences in Ca²⁺ homeostasis contribute to differential fibrogenesis in LA and RA fibroblasts. Methods: Ca²⁺ imaging, a patch clamp assay and Western blotting were performed in isolated rat LA and RA fibroblasts. Results: The LA fibroblasts exhibited a higher Ca²⁺ entry and gadolinium-sensitive current compared with the RA fibroblasts. The LA fibroblasts exhibited greater pro-collagen type I, type III, phosphorylated Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), phosphorylated phospholipase C (PLC), stromal interaction molecule 1 (STIM1) and transient receptor potential canonical (TRPC) 3 protein expression compared with RA fibroblasts. In the presence of 1 mmol/L ethylene glycol tetra-acetic acid (EGTA, Ca²⁺ chelator), the LA fibroblasts had similar pro-collagen type I, type III and phosphorylated CaMKII expression compared with RA fibroblasts. Moreover, in the presence of KN93 (a CaMKII inhibitor, 10 μmol/L), the LA fibroblasts had similar pro-collagen type I and type III compared with RA fibroblasts. Conclusion: The discrepancy of phosphorylated PLC signaling and gadolinium-sensitive Ca²⁺ channels in LA and RA fibroblasts induces different levels of Ca²⁺ influx, phosphorylated CaMKII expression and collagen production.

Transcatheter ablation for atrial fibrillation in patients with hypertrophic cardiomyopathy: Long-term results and clinical outcomes

INTRODUCTION

Radiofrequency transcatheter ablation (RFCA) for atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM) has been proven feasible. However, the long-term results of RFCA and its impact on clinical course of HCM are unknown. The aim of this study was to analyse clinical outcomes and long-term efficacy of RFCA in a multicentre cohort of patients with HCM and concomitant AF.

METHODS

Patients with HCM and AF consecutively undergoing RFCA were included. Ablation failure was defined as recurrence of AF, atrial tachycardia, or flutter lasting more than 3 min and occurring after the blanking period.

RESULTS

Overall, 116 patients with symptomatic AF refractory to antiarrhythmic drugs were included. Over a median follow-up of 6.0 years (interquartile range: 3.0-8.9 years) recurrence rate after a single RFCA was 32.3 per 100 patient/years with 26% of patients free from AF relapses at 6-year follow-up. Among patients experiencing AF recurrence, 51 (66%) underwent at least one redo-procedure. The overall recurrence rate considering redo-procedures was 12.6 per 100 patients/years with 53% of patients free from AF relapses at 6 years. At last follow-up, with an average of 1.6 procedures, 67 (61%) patients were in sinus rhythm (SR). Patients remaining in SR showed better functional status compared with those experiencing arrhythmic recurrences (NYHA Class 1.6 ± 0.1 vs. 2.0 ± 0.1, p = .009).

CONCLUSIONS

RFCA of AF in HCM patients is an effective and safe strategy favoring long-term SR maintenance, reduction of atrial arrhythmic events, and improved functional status. However, most patients need repeat procedures and continuation of antiarrhythmic drugs.

The differences of atrial thrombus locations and variable response to anticoagulation in nonvalvular atrial fibrillation with ventricular cardiomyopathy

OBJECTIVES

This study aims to research the clinical features of atrial thrombi in patients with nonvalvular atrial fibrillation (AF).

METHODS

This study included 191 patients of AF who had atrial thrombi. One hundred and twenty-eight of them were assigned into nonventricular cardiomyopathy group (non-VCM), and the remaining 63 into ventricular cardiomyopathy group (VCM). After atrial thrombi diagnosed, all patients had taken oral anticoagulant therapy. The resolution rates of thrombi within 12 months were compared between the two groups, as well as the locations of thrombi.

RESULTS

Of all 191 patients, 161 had thrombi only detected in left atrial appendage (LAA), 20 in both left atrium (LA) and LAA, six in LA only, and four in right atrium only. More patients had thrombi out of LAA in the VCM group than in the non-VCM group (30.2% vs 8.6%, P < .001). After propensity score matching, the atrial thrombi were resolved faster in the non-VCM group than in the VCM group (mean time length: 22 ± 2 weeks vs 30 ± 3 weeks, P = .038), and the resolution rate within 12 months was higher in the non-VCM group than in the VCM group (88.7% vs 61.4%, Log-rank, P = .038). In Cox proportional hazards model, absence of ventricular cardiomyopathy was an independent predictor for the resolution of atrial thrombus (hazard ratio: 1.76; P = .035).

CONCLUSIONS

The patients of atrial fibrillation with ventricular cardiomyopathies have higher incidence of thrombosis in the body of left atrium or right atrium. And the resolution rate was lower in these patients.

GSK3 modulation in acute lung injury, myocarditis and polycystic kidney disease-related aneurysm

GSK3 are involved in different physical and pathological conditions and inflammatory regulated by macrophages contribute to significant mechanism. Infection stimuli may modulate GSK3 activity and influence host cell adaption, immune cells infiltration or cytokine expressions. To further address the role of GSK3 modulation in macrophages, the signal transduction of three major organs challenged by endotoxin, virus and genetic inherited factors are briefly introduced (lung injury, myocarditis and autosomal dominant polycystic kidney disease). As a result of pro-inflammatory and anti-inflammatory functions of GSK3 in different microenvironments and stages of macrophages (M1/M2), the rational resolution should be considered by adequately GSK3.

Feasibility and functional correlates of left atrial volume changes during stress echocardiography in chronic coronary syndromes

An enlarged left atrial volume index (LAVI) at rest mirrors increased LA pressure and/or impairment of LA function. A cardiovascular stress may acutely modify left atrial volume (LAV) within minutes. Aim of this study was to assess the feasibility and functional correlates of LAV-stress echocardiography (SE) Out of 514 subjects referred to 10 quality-controlled labs, LAV-SE was completed in 490 (359 male, age 67 ± 12 years) with suspected or known chronic coronary syndromes (n = 462) or asymptomatic controls (n = 28). The utilized stress was exercise in 177, vasodilator in 167, dobutamine in 146. LAV was measured with the biplane disk summation method. SE was performed with the ABCDE protocol. The intra-observer and inter-observer LAV variability were 5% and 8%, respectively. ∆-LAVI changes (stress-rest) were negatively correlated with resting LAVI (r = - 0.271, p < 0.001) and heart rate reserve (r = -.239, p < 0.001). LAV-dilators were defined as those with stress-rest increase ≥ 6.8 ml/m², a cutoff derived from a calculated reference change value above the biological, analytical and observer variability of LAVI. LAV dilation occurred in 56 patients (11%), more frequently with exercise (16%) and dipyridamole (13%) compared to dobutamine (4%, p < 0.01). At multivariable logistic regression analysis, B-lines ≥ 2 (OR: 2.586, 95% CI = 1.1293-5.169, p = 0.007) and abnormal contractile reserve (OR: 2.207, 95% CI = 1.111-4.386, p = 0.024) were associated with LAV dilation. In conclusion, LAV-SE is feasible with high success rate and low variability in patients with chronic coronary syndromes. LAV dilation is more likely with reduced left ventricular contractile reserve and pulmonary congestion.

Identification of Circular RNA-MicroRNA-Messenger RNA Regulatory Network in Atrial Fibrillation by Integrated Analysis

BACKGROUND

Circular RNA (circRNA) is a noncoding RNA that forms a closed-loop structure, and its abnormal expression may cause disease. We aimed to find potential network for circRNA-related competitive endogenous RNA (ceRNA) in atrial fibrillation (AF).

METHODS

The circRNA, miRNA, and mRNA expression profiles in the heart tissue from AF patients were retrieved from the Gene Expression Omnibus database and analyzed comprehensively. Differentially expressed circRNAs (DEcircRNAs), differentially expressed miRNAs (DEmiRNAs), and differentially expressed mRNAs (DEmRNAs) were identified, followed by the establishment of DEcircRNA-DEmiRNA-DEmRNA regulatory network. Functional annotation analysis of host gene of DEcircRNAs and DEmRNAs in ceRNA regulatory network was performed. In vitro experiment and electronic validation were used to validate the expression of DEcircRNAs, DEmiRNAs, and DEmRNAs.

RESULTS

A total of 1611 DEcircRNAs, 51 DEmiRNAs, and 1250 DEmRNAs were identified in AF. The DEcircRNA-DEmiRNA-DEmRNA network contained 62 circRNAs, 14 miRNAs, and 728 mRNAs. Among which, two ceRNA regulatory pairs of hsa-circRNA-100053-hsa-miR-455-5p-TRPV1 and hsa-circRNA-005843-hsa-miR-188-5p-SPON1 were identified. In addition, six miRNA-mRNA regulatory pairs including hsa-miR-34c-5p-INMT, hsa-miR-1253-DDIT4L, hsa-miR-508-5p-SMOC2, hsa-miR-943-ACTA1, hsa-miR-338-3p-WIPI1, and hsa-miR-199a-3p-RAP1GAP2 were also obtained. MTOR was a significantly enriched signaling pathway of host gene of DEcircRNAs. In addition, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, and hypertrophic cardiomyopathy were remarkably enriched signaling pathways of DEmRNAs in DEcircRNA-DEmiRNA-DEmRNA regulatory network. The expression validation of hsa-circRNA-402565, hsa-miR-34c-5p, hsa-miR-188-5p, SPON1, DDIT4L, SMOC2, and WIPI1 was consistent with the integrated analysis.

CONCLUSION

We speculated that hsa-circRNA-100053-hsa-miR-455-5p-TRPV1 and hsa-circRNA-005843-hsa-miR-188-5p-SPON1 interaction pairs may be involved in AF.

A new clinical risk score for predicting the prevalence of low-voltage areas in patients undergoing atrial fibrillation ablation

INTRODUCTION

Although the presence of left atrial low-voltage areas (LVAs) is strongly associated with the recurrence of atrial fibrillation (AF) after ablation, few methods are available to classify the prevalence of LVAs. The purpose of this study was to establish a risk score for predicting the prevalence of LVAs in patients undergoing ablation for AF.

METHODS

We enrolled 1004 consecutive patients who underwent initial ablation for AF (age, 68 ± 10 years old; female, 346 (34%); persistent AF, 513 (51%)). LVAs were deemed present when the voltage map after pulmonary vein isolation demonstrated low-voltage areas with a peak-to-peak bipolar voltage of <0.5 mV covering ≥5 cm² of the left atrium.

RESULTS

LVAs were present in 206 (21%) patients. The SPEED score was obtained as the total number of independent predictors as identified on multivariate analysis, namely female sex (odds ratio [OR], 3.4 [95% confidence interval {CI} 2.2-5.2], p < .01), persistent AF (OR, 1.8 [95% CI, 1.1-3.0], p = .02), age ≥ 70 years (OR, 2.3 [95% CI, 1.5-3.4], p < .01), elevated brain natriuretic peptide ≥100 pg/ml or N-terminal probrain natriuretic peptide ≥400 pg/ml (OR, 1.7 [95% CI, 1.02-2.8], p = .04), and diabetes mellitus (OR, 1.8 [95% CI, 1.1-2.8], p = .02). LVAs were more frequent in patients with a higher SPEED score, and prevalence increased with each additional SPEED score point (OR, 2.4 [95% CI, 2.0-2.8], p < .01).

CONCLUSION

The SPEED score accurately predicts the prevalence of LVAs in patients undergoing ablation for AF.

Prognostic impact of atrial fibrillation in hypertrophic cardiomyopathy: a systematic review

BACKGROUND

Atrial fibrillation (AF) is an important arrhythmia in hypertrophic cardiomyopathy (HCM).

OBJECTIVES

To conduct a systematic review of published literature to: (a) assess the incidence of AF in HCM and (b) examine the impact of AF on risk of thromboembolism, heart failure, sudden death and mortality in HCM.

METHODS

Search of all major databases (Pubmed, MEDLINE, Embase, Cochrane, Scopus, Web of Science) was performed to April 2020 using the search terms "atrial fibrillation" AND/OR "hypertrophic cardiomyopathy" in the title or abstract. 51 of the 1,565 citations met the inclusion criteria.

RESULTS

Using random-effects modelling, the estimated pooled prevalence of AF amongst 21,887 HCM patients (36 studies) was 22.3% (95%, 19.9-24.8) and the pooled incidence of AF was 2.5 cases per person-years (95% CI 1.9-3.0). 15,444 patients from 28 studies were included in analysis of outcome data (mean age was 49.9 years; 32.7% female; mean LVEF 69%). Over a median follow up duration of 6.9 years (range 2.8-11.7 years), AF, compared to sinus rhythm (SR), was associated with significantly increased risk of thromboembolism [relative risk (RR) 7.0; 95% CI 4.6-10.7; I² = 57%], heart failure (RR 2.8; 95% CI 1.6-4.6; I² = 82%), sudden death (RR 1.7; 95% CI 1.3-2.3; I² = 0%), and all-cause mortality (RR 2.5; 95% CI 1.8-3.4; I² = 69%).

CONCLUSIONS

AF is highly prevalent in patients with HCM. The presence of AF is associated with major adverse clinical outcomes. These findings suggest that both, aggressive screening and treatment of AF, are likely to have major prognostic impact on outcomes in HCM. Incidence, prevalence and prognostic impact of AF in HCM. In this systematic review, AF incidence was 2.5 cases per-person years, prevalence was 22.3%. AF in HCM was associated with a seven-fold increased risk of thromboembolism, 2.8-fold increased risk of heart failure, 1.7-fold increased risk of sudden death and 2.5-fold increased risk of all-cause mortality.

Atrial fibrillation in patients with inherited cardiomyopathies

Atrial fibrillation (AF) often complicates the course of inherited cardiomyopathies and, in some cases, may be the presenting feature. Each inherited cardiomyopathy has its own peculiar pathogenetic characteristics that can contribute to the development and maintenance of AF. Atrial fibrillation may occur as a consequence of disease-specific defects, non-specific cardiac chamber changes secondary to the primary illness, or a combination thereof. The presence of AF can denote a turning point in the progression of the disease, promoting clinical deterioration and increasing morbidity and mortality. Furthermore, the management of AF can be particularly challenging in patients with inherited cardiomyopathies. In this article, we review the current information on the prevalence, pathophysiology, risk factors, and treatment of AF in three different inherited cardiomyopathies: hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia/cardiomyopathy, familial dilated cardiomyopathy, and left ventricular non-compaction cardiomyopathy.

Tilt-table Echocardiography Unmasks Early Diastolic Dysfunction in Patients With Hemoglobinopathies

Individuals with hemoglobinopathy (sickle cell anemia and thalassemia major) are at risk for cardiac complications such as heart failure and cardiomyopathy. Diastolic dysfunction is known to precede systolic dysfunction in many cardiac diseases. This study sought to determine whether changes in left atrial (LA) function during manipulation of cardiac preload by tilt-table echocardiography can unmask subclinical diastolic dysfunction in pediatric patients with hemoglobinopathies. Eleven sickle cell anemia, 9 transfusion-dependent thalassemia major, and 10 control subjects underwent tilt-table echocardiogram in the supine (loading) and 30-degree upright (unloading) positions and cardiac magnetic resonance imaging (MRI). Echocardiography assessed LA and left ventricular (LV) strain, strain rate, mitral inflow, and annular velocities. MRI assessed LV function, myocardial T1 and T2* for iron deposition. Both thalassemia major and sickle cell anemia patients had normal LV function and no evidence of cardiac iron deposition on MRI T2* measurements. During cardiac loading, controls appropriately increased LA conduit (P=0.002) and reservoir strain (P=0.002), mitral e' velocity (P<0.0001) and medial e' velocity (P=0.002), while the hemoglobinopathy patients showed no change in these parameters. In pediatric sickle cell anemia and thalassemia, tilt-table echocardiography unmasked a failure to augment LA function in response to loading, suggesting altered myocardial relaxation is present, before evidence of iron overload or systolic dysfunction.

Implication of Preoperative Existence of Atrial Fibrillation on Hemocompatibility-Related Adverse Events During Left Ventricular Assist Device Support

BACKGROUND

Hemocompatibility-related adverse events (HRAEs) are substantial issues in patients with left ventricular assist devices (LVADs). Atrial fibrillation (AF) is associated with worse prognosis in patients with heart failure (HF), but its effect on HRAEs following LVAD implantation remain uncertain.Methods and Results:Data from the Japanese Mechanically Assisted Circulatory Support registry of consecutive patients who received HeartMate II LVADs and were followed for 1 year were retrospectively reviewed. Among 190 patients, 23 had AF and 167 had sinus rhythm. The AF group had comparable baseline characteristics with the non-AF group except for their higher age (53 vs. 42 years, P<0.001). Following LVAD implantation, most cases of AF (73%) persisted. Antiplatelet therapy, anticoagulation therapy, and LVAD speed following LVAD implantation were comparable between groups (P>0.05 for all). The 1-year survival free from HRAEs was comparable between groups (83% vs. 76%, P=0.52). Event rates of the breakdown of HRAEs were comparable between groups except for a relatively higher rate of surgically managed pump thrombosis in the AF group (0.16 vs. 0.04, incidence rate ratio 3.75, 95% confidence interval 0.87-16.1, P=0.075). These trends still remained with propensity score-matched comparison.

CONCLUSIONS

Existence of AF had no effect on the development of HRAEs following LVAD implantation. The need to aggressively treat AF before or after LVAD implantation needs further investigation.

Biomarkers of Atrial Fibrillation in Metabolic Syndrome

Whether the increased atrial fibrillation (AF) risk in metabolic syndrome (MetS) patients is due to the syndrome as a whole or simply the sum of the risks of its individual component parts is still obscure. These two clinical entities share many pathophysiological links and thus distinction between a casual observation and a significant association is difficult. Biomarkers associated with pathogenesis of AF in the context of MetS have the ability to refine future risk prediction. In the present review we identify circulating substances that could be regarded as potential biomarkers for prediction of incident AF, or of cardiovascular events in the setting of AF in patients with MetS. Cardiac myocyte injury and stress markers (troponin and natriuretic peptides), markers of renal function (glomeral filtration rate, cystatin-C), and inflammation markers/mediators (interleukin- 6, CRP) are promising biomarkers of patients with AF and MetS.

The atrial uremic cardiomyopathy regression in patients after kidney transplantation - the prospective echocardiographic study

BACKGROUND

In patients with end stage renal disease (ESRD), left ventricular (LV) hypertrophy with impaired LV function, which is called uremic cardiomyopathy (UC) is often observed. The UC historically has been considered a contraindication for kidney transplantation (KTx). Currently, moderate LV dysfunction does not exclude the possibility of KTx. The amelioration of uremia after KTx improved cardiac function in patients with LV dysfunction. There is a little information on the function of the left atrium (LA) after the KTx procedure. There are no studies evaluating (LA) changes in patients with UC after KTx and determining the possibility of inhibiting the occurrence of LA unfavourable changes (remodelling) and even a possible LA recovery process (reverse remodelling) as a result of a successful KTx. The aim of the study was to assess the LA reverse remodelling in patients with ESRD undergoing KTx.

METHODS

The study group consisted of 42 patients, aged 43.3 ± 12.6 followed for 36 months after a deceased donor KTx. The patients were studied at five time points: 1, 3, 6, 12 and 36 months after KTx. In all patients transthoracic echocardiography was performed in order to assess the following LA planimetric parameters: LAmax, LAmin, LAwaveP. LAshortmax, LAshortmin, LAshortwaveP, LAlongmax, LAlongmin, LAlongwaveP, LAcircmax and LAareamax, volumentric parameters: LA volume (LAV), LA volume index (LAVI), and hemodynamic indices: LA ejection fraction (LAEF), LA active emptying fraction (LAAE), LA passive emptying fraction (LAPE), LA index of expansion (LAIE) and LA fractional shortening (LAFS).

RESULTS

The LAVI values were 34.63 ± 10.34 ml/m2, 32.24 ± 9.59 ml/m2 (p < 0,001), 31.36 ± 9.20 ml/m2 (p < 0,001), 28.29 ± 8.32 ml/m2 (p < 0,001) and 27.57 ± 8.40 ml/m2 (p < 0,001), after: 1, 3, 6, 12 and 36 months after KTx, respectively. The reduction of the LA size was accompanied by gradual LA contractility improvement, which was manifested as an increase of the LA hemodynamic indices such as LAEF, LAAE, LAIE, LAFS and a decrease of LAPE.

CONCLUSIONS

LA remodelling secondary to atrial uraemic cardiomyopathy is an example of complex cardiomyopathy with elements characteristic of both congestive and infiltrative cardiomyopathy. Early LAVI reduction post KTx mostly depends on changed haemodynamic conditions, whereas the main reason for further decrease of LAVI values is related to resolution of uraemic toxaemia.

Feasibility of late gadolinium enhancement magnetic resonance imaging to detect ablation lesion gaps in patients undergoing cryoballoon ablation of paroxysmal atrial fibrillation

BACKGROUND

Although late gadolinium enhancement magnetic resonance imaging (LGE-MRI) allows the identification of lesions and gaps after a cryothermal balloon (CB) ablation of paroxysmal atrial fibrillation (PAF), the accuracy has not yet been well established.

METHODS

The subjects consisted of 10 consecutive patients who underwent a second ablation procedure among our cohort of 80 patients who underwent LGE-MRI after the CB ablation of PAF. LGE-MRI scar regions were compared with electroanatomical mapping during the second procedure. In the analysis, the unilateral pulmonary vein (PV) antrum was divided into 7 regions.

RESULTS

The gap characterization analysis was performed in 140 regions around 40 PVs in total. There were 16 LGE-MRI gaps around 11 PVs (mean 1.6 ± 1.4 gaps/patient) in 7 patients and 14 electrical gaps around 10 PVs in 8 patients (mean 1.4 ± 1.1 gaps/patient). The locations of 13 electrical gaps were well matched to that on the LGE-MRI, whereas the remaining 1 electrical gap had not been predicted on the LGE-MRI. Compared to the electrical gaps in the second procedure, the sensitivity and specificity of the LGE-MRI gaps were 93% (13 LGE-MRI gaps of 14 electrical gaps) and 98% (123 LGE-MRI scars out of 126 electrical scars), respectively.

CONCLUSION

LGE-MRI can accurately localize the lesion gaps after CB ablation of PAF.

Atrial remodelling and function: implications for atrial fibrillation surgery

The exact mechanism of atrial fibrillation (AF) is still incompletely understood. A number of alterations that impact focal electrical discharge, the atrial substrate and modulating factors contribute to its pathogenesis. Atrial remodelling (resulting in atrial cardiomyopathy) sets the stage for AF development. Once present, AF results in the loss of synchronized atrial contraction, which affects ventricular filling and atrial reservoir and conduit functions. Passive atrial function is particularly important in patients with left ventricular diastolic dysfunction. AF can cause tachycardiomyopathy, a mostly reversible cardiac alteration induced by tachycardia. At a structural level, atrial support is also instrumental to the function of atrioventricular valves. All of these functions can be recovered to variable degrees via rhythm control strategies. Surgical and hybrid ablation show very promising results, especially in patients with a more advanced disease substrate. This review highlights the pathophysiological aspects of AF related to left atrial function and their practical implications for surgical rhythm management.

Shensong Yangxin capsule reduces atrial fibrillation susceptibility by inhibiting atrial fibrosis in rats with post-myocardial infarction heart failure

Purpose

Shensong Yangxin (SSYX) capsule is a traditional Chinese medicine that has been used widely to treat cardiac arrhythmia. This study aimed to assess whether SSYX prevents atrial fibrillation (AF) after chronic myocardial infarction (MI)-induced heart failure and to determine the underlying mechanisms.

Materials and methods

The study included 45 male Sprague Dawley rats. The rats underwent MI induction or sham surgery. One week after MI induction surgery, we performed serial echocardiography and administered SSYX capsule to some rats that experienced MI. After 4 weeks of treatment, AF inducibility was assessed with transesophageal programmed electrical stimulation technology. Additionally, multielectrode array assessment, histological analysis, and Western blot analysis were performed.

Results

AF inducibility was significantly lower in SSYX rats than in MI rats (33.3% vs 73.3%, P<0.05). Additionally, conduction velocities in the left atrium were greater in SSYX rats than in MI rats. Moreover, SSYX decreased left atrial fibrosis, downregulated TGF-β1, MMP-9, TIMP-I, and type I and III collagen expressions, and inhibited the differentiation of cardiac fibroblasts to myofibroblasts.

Conclusion

SSYX reduces AF inducibility after MI by improving left atrial conduction function via the inhibition of left atrial fibrosis. It prevents the development of an MI-induced vulnerable substrate for AF.

Atrial Fibrillation in Patients with Heart Failure: Current State and Future Directions

Heart failure affects nearly 26 million people worldwide. Patients with heart failure are frequently affected with atrial fibrillation, and the interrelation between these pathologies is complex. Atrial fibrillation shares the same risk factors as heart failure. Moreover, it is associated with a higher-risk baseline clinical status and higher mortality rates in patients with heart failure. The mechanisms by which atrial fibrillation occurs in a failing heart are incompletely understood, but animal studies suggest they differ from those that occur in a healthy heart. Data suggest that heart failure-induced atrial fibrosis and atrial ionic remodeling are the underlying abnormalities that facilitate atrial fibrillation. Therapeutic considerations for atrial fibrillation in patients with heart failure include risk factor modification and guideline-directed medical therapy, anticoagulation, rate control, and rhythm control. As recommended for atrial fibrillation in the non-failing heart, anticoagulation in patients with heart failure should be guided by a careful estimation of the risk of embolic events versus the risk of hemorrhagic episodes. The decision whether to target a rate-control or rhythm-control strategy is an evolving aspect of management. Currently, both approaches are good medical practice, but recent data suggest that rhythm control, particularly when achieved through catheter ablation, is associated with improved outcomes. A promising field of research is the application of neurohormonal modulation to prevent the creation of the "structural substrate" for atrial fibrillation in the failing heart.

Histopathological Aspects of the Myocardium in Dilated Cardiomyopathy

Dilated cardiomyopathy is the most common form of cardiac muscle disease, accounting for approximately 60% of all cardiomyopathies. We proposed to identify histopathological changes of the myocardium in dilative cardiomyopathy. This study comprised a total of 19 cases, represented by myocardial fragments from deceased patients with diagnosis of dilated cardiomyopathy. Histopathological analysis allowed changes to be observed for both myocytes and myocardial interstitial components. We have found a combination of hypertrophic, atrophic and normal myocardocytes, or associated with the presence of hydropic changes. We rarely identified the aspect of myocytosis, cytoplasmic accumulation of lipofuscin pigment or mucinous material, and variable nuclear pleomorphism. At the interstitial level we noticed changes in fibrosis, lipomatosis and rarely the presence of inflammatory infiltrate. Histopathological characteristics of the myocardium in dilated cardiomyopathy are numerous but nonspecific, similar to those in the terminal stages of other cardiac diseases.

Left atrial dilatation in systolic heart failure: a marker of poor prognosis, not just a buffer between the left ventricle and pulmonary circulation

BACKGROUND

The relation between systolic pulmonary pressure (sPAP) and left atrium in patients with heart failure (HF) is unclear. Diastolic dysfunction, expressed as restrictive mitral filling pattern (RMP), and functional mitral regurgitation (FMR) are associated with both LA enlargement and increased sPAP. We aimed to evaluate whether atrial dilation might modulate the consequences of RMP and FMR on the pulmonary circulation of patients with HF with reduced ejection fraction (HFrEF).

METHODS

1256 HFrEF patients were retrospectively recruited in four Italian centers. Left ventricular (LVD) and atrial (LAD) diameters were measure by m-mode, and EF were measured. RMP was defined as E-wave deceleration time lower than 140 ms. FMR was quantitatively measured. sPAP was evaluated based on maximal tricuspid regurgitant velocity and estimated right atrial pressure.

RESULTS

Final study population was formed by 1005 patients because of unavailability of sPAP in 252 patients. Mean EF was 33 ± 3, 35% had RMP, 67% had mild, and 26% moderate-to-severe FMR. 69% of patients had increased sPAP. A significant association was observed between sPAP and EF, RMP, FMR, and LAD (p < 0.0001 for all). At multivariate analysis, LAD was positively associated with sPAP (p < 0.0001) independently of EF, RMP, and FMR. Analogously, LAD (p < 0.05) was associated with more severe symptoms and worse prognosis after adjustment for LV function and FMR.

CONCLUSION

LA dilation was positively associated with sPAP independently of EF, RMP, and FMR. This highlights that LA size should be considered a marker of the severity of the disease.

Left atrial volume index in patients with heart failure and severely impaired left ventricular systolic function: the role of established echocardiographic parameters, circulating cystatin C and galectin-3

Backround: Left atrial (LA) enlargement plays an important role in the development of heart failure (HF) and is a robust prognostic factor. Fibrotic processes have also been advocated to evoke HF through finite signalling proteins.

METHODS

We examined the association of two such proteins, cystatin C (CysC) and galectin-3 (Gal-3), and other clinical, echocardiographic and biochemical parameters with LA volume index (LAVi) in patients with HF with severely impaired left ventricular ejection fraction (LVEF). Severe renal, liver, autoimmune disease and cancer were exclusion criteria.

RESULTS

A total of 40 patients with HF (31 men, age 66.6 ± 1.7) with LVEF = 25.4 ± 0.9% were divided into two groups according to the mean LAVi (51.03 ± 2.9 ml/m2) calculated by two-dimensional transthoracic echocardiography. Greater LAVi was positively associated with LV end-diastolic volume ( p = 0.017), LV end-systolic volume ( p = 0.025), mitral regurgitant volume (MRV) ( p = 0.001), right ventricular systolic pressure (RVSP) ( p < 0.001), restrictive diastolic filling pattern ( p = 0.003) and atrial fibrillation ( p = 0.005). Plasma CysC was positively correlated with LAVi ( R2 = 0.135, p = 0.019) and log-transformed plasma Gal-3 ( R2 = 0.109, p = 0.042) by simple linear regression analysis. Stepwise multiple linear regression analysis showed that only MRV ( t = 2.236, p = 0.032), CysC ( t = 2.467, p = 0.019) and RVSP ( t = 2.155, p = 0.038) were significant predictors of LAVi.

CONCLUSIONS

Apart from known determinants of LAVi, circulating CysC and Gal-3 were associated with greater LA dilatation in patients with HF with reduced LVEF. Interestingly, the correlation between these two fibrotic proteins was positive.

A comparison of left and right atrial fibroblasts reveals different collagen production activity and stress-induced mitogen-activated protein kinase signalling in rats

AIM

Atrial fibrosis plays a pivotal role in the pathophysiology of heart failure (HF). The left atrium (LA) experiences greater fibrosis than the right atrium (RA) during HF. It is not clear whether LA cardiac fibroblasts contain distinctive activities that predispose LA to fibrosis.

METHODS

LA and RA fibrosis were evaluated in healthy and isoproterenol-induced HF Sprague Dawley rats. Rat LA and RA primary isolated fibroblasts were subjected to proliferation assay, oxidative stress assay, cell migration analysis, collagen measurement, cytokine array and Western blot.

RESULTS

Healthy rat LA and RA had a similar extent of collagen deposition. HF significantly increased fibrosis to a greater severity in LA than in RA. Compared to isolated RA fibroblasts, the in vitro experiments showed that isolated LA fibroblasts had higher oxidative stress and exhibited higher collagen, transforming growth factor-β1, connective tissue growth factor production and less vascular endothelial growth factor (VEGF) production, but had similar migration, myofibroblast differentiation and proliferation activities. VEGF significantly increased the collagen production ability of LA fibroblasts, but not RA fibroblasts. LA fibroblasts had more phosphorylated ERK1/2 and P38 expression. ERK inhibitor (PD98059, 50 μmol L^-1 ) significantly attenuated collagen production and increased VEGF production in RA fibroblasts but not in LA fibroblasts. P38 inhibitor (SB203580, 30 μmol L^-1 ) significantly attenuated collagen production in LA fibroblasts but not in RA fibroblasts. P38 inhibitor also significantly increased VEGF production in RA and LA fibroblasts.

CONCLUSIONS

Differences in profibrotic activity between LA and RA fibroblasts may be caused by different responses to mitogen-activated protein kinase signalling.

Atrial Fibrillation in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disorder with a spectrum of clinical manifestations. Patients with HCM are predisposed to developing atrial fibrillation (AF) due primarily to advanced diastolic dysfunction and left atrial (LA) dilatation and remodelling. Atrial fibrillation causes a progressive symptomatic and functional decline, as well as increased thromboembolic risk and mortality, particularly in the setting of rapid ventricular rates and left ventricular outflow tract (LVOT) obstruction. The mainstay of management of AF in HCM is a combination of non-pharmacological lifestyle and risk factor modification, long-term anticoagulation, and rhythm control with antiarrhythmic medications. There is a growing body of evidence indicating that an early and aggressive rhythm control strategy may result in more favourable outcomes.

Atrial Fibrillation: Epidemiology, Pathophysiology, and Clinical Outcomes

The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a vulnerable atrial substrate and that the formation and composition of this substrate may vary depending on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established that advanced age, male sex, and European ancestry are prominent AF risk factors. Other modifiable risk factors include sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and elevated blood pressure predispose to AF, and each factor has been shown to induce structural and electric remodeling of the atria. Both heart failure and myocardial infarction increase risk of AF and vice versa creating a feed-forward loop that increases mortality. Other cardiovascular outcomes attributed to AF, including stroke and thromboembolism, are well established, and epidemiology studies have championed therapeutics that mitigate these adverse outcomes. However, the role of anticoagulation for preventing dementia attributed to AF is less established. Our review is a comprehensive examination of the epidemiological data associating unmodifiable and modifiable risk factors for AF and of the pathophysiological evidence supporting the mechanistic link between each risk factor and AF genesis. Our review also critically examines the epidemiological data on clinical outcomes attributed to AF and summarizes current evidence linking each outcome with AF.

Atrial Fibrillation and Anticoagulation in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) represents a common inherited cardiac disorder with well-known complications Including stroke and sudden cardiac death. There is a recognised association between HCM and the development of AF. This review describes the epidemiology of AF within the HCM population and analyses the risk factors for the development of AF. It further discusses the outcomes associated with AF in this population, including the evidence in support of higher stroke risk in patients with HCM with AF compared with the general AF population. Finally, the evidence and recommendations for anticoagulation in this patient group are addressed.

The State of the Art: Atrial Fibrillation Epidemiology, Prevention, and Treatment

As the most common sustained arrhythmia in adults, atrial fibrillation (AF) is an established and growing epidemic. To provide optimal patient care, it is important for clinicians to be aware of AF's epidemiological trends, methods of risk reduction, and the various available treatment modalities. Our understanding of AF's pathophysiology has advanced, and with this new understanding has come advancements in prevention strategies as well as pharmacological and nonpharmacological treatment options. Following PubMed and MEDLINE searches for AF risk factors, epidemiology, and therapies, we reviewed relevant articles (and bibliographies of those articles) published from 2000 to 2016. This "state-of-the-art" review provides a comprehensive update on the understanding of AF in the world today, contemporary therapeutic options, and directions of ongoing and future study.

The differences in left atrial function between ischemic and idiopathic dilated cardiomyopathy patients: A two-dimensional speckle tracking imaging study

PURPOSE

To evaluate left atrial (LA) function in patients with ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy via two-dimensional speckle-tracking imaging.

METHODS

We measured the LA maximum volume, minimum volume, and volume before the atrial systole, and calculated total emptying volume, expansion index, active emptying volume, and fraction. We measured strain and strain rate during systole and late diastole using two-dimensional speckle-tracking imaging, and analyzed correlations between variables.

RESULTS

We found no significant differences in LA size, left ventricle (LV) end-diastole diameter, LV ejection fraction (EF), E/A, E/e', deceleration time of the E wave, and effective mitral regurgitant orifice area between the DCM and the ICM group. However, the LA expansion index, active EF, systolic and late diastolic strain, and strain rate were lower in the ICM group (p < 0.05). The expansion index and active EF were positively correlated with the systolic strain rate and the absolute value of the late diastolic strain rate, respectively.

CONCLUSIONS

LA basic echocardiographic variables did not reflect the differences between ICM and DCM patients, but the systolic and late diastolic strain, as well as the strain rate, were lower in DCM patients. Two-dimensional speckle-tracking imaging is a promising method to differentiate these patients. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:437-445, 2016.

Challenges for 'diastology': contributions from Japanese researchers

Diastology is a study to treat diastole of the heart. Transmitral flow and pulmonary venous flow velocities recorded by pulsed Doppler echocardiography provide more important information about left ventricular (LV) diastolic dysfunction [left atrial (LA)-LV coupling] than cardiac catheterization in clinical practice; however, these waveforms are influenced by loading conditions, particularly preload. The early diastolic mitral annular and LV wall motion indices measured by tissue Doppler echocardiography can evaluate LV relaxation abnormality and filling pressure by being relatively preload independent. In addition, the role of concomitant systolic longitudinal dysfunction is well characterized in asymptomatic patients and in patients with heart failure and preserved ejection fraction. Two-dimensional speckle tracking echocardiography is an angle-independent method, and has the potential to evaluate the contraction and relaxation abnormalities in the longitudinal, circumferential, and radial directions of the LV myocardium as well as LV torsion/untwisting and, moreover, deformation of the LA myocardium and large arterial wall. As a result, this new technique can facilitate the early detection of impaired LA-LV-arterial coupling in patients before occurrence of overt heart failure symptoms.

Inhibition of the Unfolded Protein Response Mechanism Prevents Cardiac Fibrosis

Background

Cardiac fibrosis attributed to excessive deposition of extracellular matrix proteins is a major cause of heart failure and death. Cardiac fibrosis is extremely difficult and challenging to treat in a clinical setting due to lack of understanding of molecular mechanisms leading to cardiac fibrosis and effective anti-fibrotic therapies. The objective in this study was to examine whether unfolded protein response (UPR) pathway mediates cardiac fibrosis and whether a pharmacological intervention to modulate UPR can prevent cardiac fibrosis and preserve heart function.

Methodology/Principal Findings

We demonstrate here that the mechanism leading to development of fibrosis in a mouse with increased expression of calreticulin, a model of heart failure, stems from impairment of endoplasmic reticulum (ER) homeostasis, transient activation of the unfolded protein response (UPR) pathway and stimulation of the TGFβ1/Smad2/3 signaling pathway. Remarkably, sustained pharmacologic inhibition of the UPR pathway by tauroursodeoxycholic acid (TUDCA) is sufficient to prevent cardiac fibrosis, and improved exercise tolerance.

Conclusions

We show that the mechanism leading to development of fibrosis in a mouse model of heart failure stems from transient activation of UPR pathway leading to persistent remodelling of cardiac tissue. Blocking the activation of the transiently activated UPR pathway by TUDCA prevented cardiac fibrosis, and improved prognosis. These findings offer a window for additional interventions that can preserve heart function.