Effect of catheter ablation on pre-existing abnormalities of left atrial systolic, diastolic, and neurohormonal functions in patients with chronic heart failure and atrial fibrillation

SIRT3 sulfhydration using hydrogen sulfide inhibited angiotensin II-induced atrial fibrosis and vulnerability to atrial fibrillation via suppression of the TGF-β1/smad2/3 signalling pathway

Atrial fibrosis is associated with the occurrence of atrial fibrillation (AF) and regulated by the transforming growth factor-β1 (TGF-β1)/Smad2/3 signalling pathway. Unfortunately, the mechanisms of regulation of TGF-β1/Smad2/3-induced atrial fibrosis and vulnerability to AF remain still unknown. Previous studies have shown that sirtuin3 (SIRT3) sulfhydration has strong anti-fibrotic effects. We hypothesised that SIRT3 sulfhydration inhibits angiotensin II (Ang-II)-induced atrial fibrosis via blocking the TGF-β1/Smad2/3 signalling pathway. In this study, we found that SIRT3 expression was decreased in the left atrium of patients with AF compared to that in those with sinus rhythm (SR). In vitro, SIRT3 knockdown by small interfering RNA significantly expanded Ang-II-induced atrial fibrosis and TGF-β1/Smad2/3 signalling pathway activation, whereas supplementation with Sodium Hydrosulfide (NaHS, exogenous hydrogen sulfide donor and sulfhydration agonist) and SIRT3 overexpression using adenovirus ameliorated Ang-II-induced atrial fibrosis. Moreover, we observed suppression of the TGF-β1/Smad2/3 pathway when Ang-II was combined with NaHS treatment, and the effect of this co-treatment was consistent with that of Ang-II combined with LY3200882 (Smad pathway inhibitor) on reducing atrial fibroblast proliferation and cell migration in vitro. Supplementation with dithiothreitol (DTT, a sulfhydration inhibitor) and adenovirus SIRT3 shRNA blocked the ameliorating effect of NaHS and AngII co-treatment on atrial fibrosis in vitro. Finally, continued treatment with NaHS in rats ameliorated atrial fibrosis and remodelling, and further improved AF vulnerability induced by Ang-II, which was reversed by DTT and adenovirus SIRT3 shRNA, suggesting that SIRT3 sulfhydration might be a potential therapeutic target in atrial fibrosis and AF.

Heart Failure score and outcomes in patients with preserved ejection fraction after catheter ablation for atrial fibrillation

AIMS

Atrial fibrillation (AF) is frequently associated with heart failure with preserved ejection fraction (HFpEF), but the diagnosis and prediction of the outcomes of HFpEF are difficult. Notably, the Heart Failure Association of the European Society of Cardiology proposed the use of the HFA-PEFF score in the diagnosis of HFpEF. This study aimed to assess the prognostic value of the pre- and post-procedural HFA-PEFF scores in patients with preserved ejection fraction (EF) after catheter ablation (CA) for AF. The primary endpoint was a composite of cardiac hospitalization for cardiovascular events and all-cause mortality. The secondary endpoint was AF recurrence.

METHODS AND RESULTS

Overall, 354 patients with AF and preserved EF who underwent CA as well as blood tests and transthoracic echocardiography 2 weeks before and 6 months after CA from January 2018 to December 2019 were retrospectively enrolled in the study. In the 354 participants, univariate analysis showed that the post-procedural HFA-PEFF score was associated with a 3-year risk of the primary endpoint (hazard ratio [HR] = 3.73; 95% confidence interval [CI] = 2.07-6.73; P < 0.001), whereas the pre-procedural HFA-PEFF score was not (HR = 1.24, 95% CI = 0.82-1.86, P = 0.307). Further, the association between the post-procedural HFA-PEFF score and primary endpoint was not modified even after including other relevant variables into the score. Similar to the primary endpoint, the post-procedural HFA-PEFF score was associated with the 3-year risk of AF recurrence (P < 0.001).

CONCLUSIONS

In patients with preserved EF undergoing AF ablation, the HFA-PEFF score at 6 months after CA was associated with the primary endpoint and AF recurrence at the 3-year follow-up.

The Role of Epicardial Adipose Tissue-Derived Proteins in Heart Failure with Preserved Ejection Fraction and Atrial Fibrillation: A Bioinformatics Analysis

Background

The accumulation of epicardial adipose tissue (EAT) is associated with cardiometabolic risks and adverse outcomes in heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF). This study aims to identify genes secreted by EAT that contribute to the shared pathogenesis of HFpEF and AF, potentially serving as biomarkers for diagnosis.

Methods

Data sets from the GEO database for HFpEF-EAT, HFpEF-heart tissue, AF-EAT, AF-PBMC, and AF-heart tissue were analyzed. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) identified key genes in EAT linked to HFpEF and AF. Functional enrichment and connectivity map analyses explored common pathways and therapeutic targets. Machine learning techniques, including LASSO regression, random forest, and support vector machine, identified shared biomarkers. CIBERSORT was used to assess immune cell infiltration, while gene set enrichment analysis identified pathways related to hub genes. Receiver operating characteristic (ROC) curve analysis and experimental validation assessed the bioinformatics findings.

Results

In the HFpEF dataset, 200 key genes were identified by intersecting HFpEF-EAT, HFpEF-heart tissue, WGCNA analyses, and secretory proteins. For AF, 232 related genes were identified through similar methods. Thirteen genes were common between HFpEF and AF, with two central genes, ITPKA and WNT9B, selected as potential biomarkers through machine learning and ROC analysis. Immune cell infiltration and gene set enrichment analysis revealed pathways related to ITPKA/WNT9B. These patterns were confirmed in human samples.

Conclusion

This study identified EAT-derived secretory proteins as potential biomarkers for HFpEF and AF, with ITPKA and WNT9B as central hub genes. These findings offer insights into potential diagnostic and therapeutic strategies for HFpEF and AF.

Outcomes of Atrial Fibrillation Ablation in Heart Failure Subtypes

BACKGROUND

Catheter ablation (CA) improves clinical outcomes in patients with atrial fibrillation (AF) and heart failure (HF) with reduced ejection fraction (HFrEF). We aimed to evaluate the impact of CA on clinical and quality-of-life outcomes across HF subtypes.

METHODS

All patients undergoing AF ablation at a tertiary center were enrolled in a prospective registry and included in this study (2013-2021). The primary end point was AF recurrence. Secondary end points included AF-related hospitalizations and quality-of-life outcomes. Patients were categorized according to their HF status: no HF, HFrEF, HF with mildly reduced ejection fraction (HFmrEF), and HF with preserved ejection fraction (HFpEF).

RESULTS

A total of 7020 patients were included (80% no HF, 8% HFrEF, 7% HFmrEF, and 5% HFpEF). Over 3 years, the cumulative incidence of AF recurrence after ablation was as follows: HFpEF (53%), HFmrEF (41%), HFrEF (41%), and no HF (34%); P<0.01. Multivariable Cox analyses confirmed these findings using no HF group as reference (HFpEF: hazard ratio, 1.47 [95% CI, 1.21-1.78]; HFmrEF: hazard ratio, 1.23 [95% CI, 1.04-1.45]; and HFrEF: hazard ratio, 1.17 [95% CI, 1.01-1.37]; P<0.05 for all). In all groups, CA resulted in a significant reduction of AF-related hospitalization (mean rate per 1 patient-years [before and after CA]; HFpEF [1.8 versus 0.3], HFmrEF [1.1 versus 0.2], HFrEF [1.1 versus 0.2], and no HF [1 versus 0.1]; P<0.01 for each comparison) and significant improvement in quality of life as measured by both the AF symptom severity score and the AF burden score (P<0.01 for the comparison between baseline and follow-up for each score when tested separately).

CONCLUSIONS

AF recurrence rates after CA were higher in patients with HF compared with those without HF, with patients with HFpEF being at the highest risk of recurrence. Nonetheless, CA was associated with a significant reduction in AF symptoms, AF-related hospitalization, and HF symptoms in most patients irrespective of HF subtypes.

Outcome of tailored therapy in rheumatic heart disease with persistent atrial fibrillation (RHD-AF)

INTRODUCTION

Rheumatic heart disease with persistent atrial fibrillation (RHD-AF) is associated with increased morbidity. However, there is no standardized approach for the maintenance of sinus rhythm (SR) in them. We aimed to determine the utility of a stepwise approach to achieve SR in RHD-AF.

METHODS

Consecutive patients with RHD-AF from July 2021 to August 2023 formed the study cohort. The stepwise approach included pharmacological rhythm control and/or electrical cardioversion (Central illustration). In patients with recurrence, additional options included AF ablation or pace and ablate strategy with conduction system pacing or biventricular pacing. Clinical improvement, NT-proBNP, 6-Minute Walk Test (6MWT), heart failure (HF) hospitalizations, and thromboembolic complications were documented during follow-up.

RESULTS

Eighty-three patients with RHD-AF (mean age 56.13 ± 9.51 years, women 72.28%) were included. Utilizing this approach, 43 (51.81%) achieved and maintained SR during the study period of 11.04 ± 7.14 months. These patients had improved functional class, lower NT-proBNP, better distance covered for 6MWT, and reduced HF hospitalizations. The duration of AF was shorter in patients who achieved SR, compared to those who remained in AF (3.15 ± 1.29 vs 6.93 ± 5.23, p = 0.041). Thirty-five percent (29) maintained SR after a single cardioversion over the study period. Only one underwent AF ablation. Of the 24 who underwent pace and ablate strategy, atrial lead was implanted in 22 (hybrid approach), and 50% of these achieved and maintained SR. Among these 24, none had HF hospitalizations, but patients who maintained SR had further improvement in clinical and functional parameters.

CONCLUSIONS

RHD-AF patients who could achieve SR with a stepwise approach, had better clinical outcomes and lower HF hospitalizations.

Biatrial myopathy in heart failure with preserved ejection fraction

AIM

Left atrial (LA) myopathy is increasingly recognized as an important phenotypic trait in heart failure (HF) with preserved ejection fraction (HFpEF). Right atrial (RA) remodelling and dysfunction also develop in HFpEF, but little data are available regarding the clinical characteristics and pathophysiology among patients with isolated LA, RA, or biatrial myopathy.

METHODS AND RESULTS

Patients with HFpEF underwent invasive haemodynamic exercise testing, comprehensive imaging including speckle tracking strain echocardiography, and clinical follow-up at Mayo Clinic between 2006 and 2018. LA myopathy was defined as LA volume index >34 ml/m2 and/or LA reservoir strain ≤24% and RA myopathy by RA volume index >39 ml/m2 in men and >33 ml/m2 in women and/or RA reservoir strain ≤19.8%. Of 476 consecutively evaluated patients with HFpEF defined by invasive exercise testing with evaluable atrial structure/function, 125 (26%) had no atrial myopathy, 147 (31%) had isolated LA myopathy, 184 (39%) had biatrial myopathy, and 20 (4%) had isolated RA myopathy. Patients with HFpEF and biatrial myopathy had more atrial fibrillation, poorer left ventricular systolic and diastolic function, more severe pulmonary vascular disease, tricuspid regurgitation, ventricular interdependence and right ventricular dysfunction, and poorer cardiac output reserve with exercise. There were 94 patients with events over a median follow-up of 2.9 (interquartile range 1.4-4.6) years. Individuals with biatrial myopathy had an 84% higher risk of HF hospitalization or death as compared to those with isolated LA myopathy (hazard ratio 1.84; 95% confidence interval 1.16-2.92, p = 0.01).

CONCLUSIONS

Biatrial myopathy identifies patients with more advanced HFpEF characterized by more severe pulmonary vascular disease, right HF, poorer cardiac reserve, and a greater risk for adverse outcomes. Further study is required to define optimal strategies to treat and prevent biatrial myopathy in HFpEF.

Ablation for atrial fibrillation improves the outcomes in patients with heart failure with preserved ejection fraction

AIMS

Patients with heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) have worse clinical outcomes than those with sinus rhythm (SR). We aim to investigate whether maintaining SR in patients with HFpEF through a strategy such as AF ablation would improve outcomes.

METHODS AND RESULTS

This is a cohort study that analysed 1034 patients (median age 69 [63-76] years, 46.2% [478/1034] female) with HFpEF and AF. Of these, 392 patients who underwent first-time AF ablation were assigned to the ablation group, and the remaining 642 patients, who received only medical therapy, were assigned to the no ablation group. The primary endpoint was a composite of all-cause death or rehospitalization for worsening heart failure. After a median follow-up of 39 months, the cumulative incidence of the primary endpoint was significantly lower in the ablation group compared to the no ablation group (adjusted hazard ratio [HR], 0.55 [95% CI, 0.37-0.82], P = 0.003) in the propensity score-matched model. Secondary endpoint analysis showed that the benefit of AF ablation was mainly driven by a reduction in rehospitalization for worsening heart failure (adjusted HR, 0.52 [95% CI, 0.34-0.80], P = 0.003). Patients in the ablation group showed a 33% relative decrease in atrial tachycardia/AF recurrence compared to the no ablation group (adjusted HR, 0.67 [95% CI, 0.54-0.84], P < 0.001).

CONCLUSION

Among patients with HFpEF and AF, the strategy of AF ablation to maintain SR was associated with a lower risk of the composite outcome of all-cause death or rehospitalization for worsening heart failure.

Totally Thoracoscopic Ablation in Patients With Recurrent Atrial Fibrillation After Catheter Ablation

BACKGROUND

The objective of this study was to evaluate the efficacy and safety of totally thoracoscopic ablation (TTA) in patients with recurrent atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA).

METHODS

From February 2012 to May 2020, 460 patients who underwent TTA were classified into two groups: CA (presence of RFCA history, n = 74) and nCA groups (absence of RFCA history, n = 386). Inverse probability of treatment weighting (IPTW) analyses were used to adjust for confounders. The primary endpoint was freedom from the composite of AF, typical atrial flutter, atypical atrial flutter and any atrial tachyarrhythmia, lasting more than 30 seconds during the follow-up. All patients were followed up at 3, 6, and 12 months via electrocardiogram and 24-hour Holter monitoring.

RESULTS

Bilateral pulmonary vein isolation (PVI) was conducted in all patients and the conduction block tests were confirmed. In the CA group, difficult PVI occasionally occurred due to structural changes, such as pericardial adhesion and fibrosis of the pulmonary venous structure, caused by a previous catheter ablation. Early complications such as stroke and pacemaker insertion were not different between the two groups. The normal sinus rhythm was maintained in 70.1% (317/460) patients after a median follow-up period of 38.1 months. The IPTW-weighted Kaplan-Meier curves revealed that freedom from AF events at 5 years was 68.4% (95% confidence interval, 62.8-74.5) in the nCA group and 31.2% (95% confidence interval, 16.9-57.5) in the CA group (P < 0.001). In IPTW-weighted Cox regression, preoperative left atrial diameter, persistent or long-standing AF, the presence of congestive heart failure and catheter ablation history were associated with AF events.

CONCLUSION

Patients in the CA group showed a higher recurrence rate of AF than those in the nCA group, while TTA was safely performed in both the groups.

Impact of pulmonary artery pressure on recurrence after catheter ablation in patients with atrial fibrillation

Background

The pulmonary veins play a major role in the pathogenesis of atrial fibrillation (AF) and may be affected by cardiac remodeling due to pulmonary vascular dysfunction. It remains to be determined whether pulmonary artery pressure (PAP) is associated with the recurrence of AF after radiofrequency catheter ablation (RFCA).

Methods

Consecutive patients with paroxysmal and persistent AF who underwent RFCA, including wide circumferential pulmonary vein isolation, were analyzed. Systolic PAP was measured using transthoracic echocardiography, and clinical outcomes were compared between patients with PAP <35 mmHg and those with PAP ≥35 mmHg.

Results

Among 2,379 patients (mean age 56.7 ± 10.6 years, 77% men), 1,893 (79.6%) had PAP <35 mmHg and 486 (20.4%) had PAP ≥35 mmHg. During the median follow-up of 25.4 months, in patients with paroxysmal AF (n = 1,294), the recurrence rate was significantly greater in the PAP ≥35 mmHg group than in the PAP <35 mmHg group (35.1% vs. 23.8%, log-rank p = 0.008). However, in patients with persistent AF (n = 1,085), the recurrence rate was not significantly different between the two groups (52.2% vs. 49.7%, log-rank p = 0.409). Multivariate analysis using Cox regression showed that PAP ≥35 mmHg was significantly associated with clinical recurrence (hazard ratio 1.19, 95% confidence interval 1.02-1.40, p = 0.027).

Conclusion

This study showed that a higher PAP was associated with an increased risk of recurrence after RFCA in patients with paroxysmal AF, suggesting a mechanism by which a pulmonary vascular pathology may cause impairment of the pulmonary veins and remodeling of the left atrium.

Subclinical Dysfunction of Left Atrial Compliance after Cryoballoon versus Radiofrequency Ablation for Paroxysmal Atrial Fibrillation

It has been suggested that cryoballoon (CB) ablation for paroxysmal atrial fibrillation (PAF) may lead to more extensive left atrial (LA) injury than radiofrequency (RF) ablation; however, results are conflicting. We sought to address this issue using modern echocardiographic techniques estimating the LA function after successful CB and RF ablation for PAF. A total of 90 patients (66% males, mean age 57 ± 10 years) successfully treated (no AF recurrences confirmed in serial 4-7 day ECG Holter monitoring) with RF (51%) or CB (49%) ablation for PAF were retrospectively studied. Echocardiography with speckle tracking (STE) was performed before and 12 months after the procedure. The peak longitudinal LA strain (LAS) and strain rate (LASR) during the reservoir (r), conduit (cd), and contraction (ct) phases were measured in sinus rhythm. Analysis of covariance was applied to compare changes in the echocardiographic parameters over time with the baseline measurements as covariance and the type of ablation as the factor. The parallelism of the slopes of the covariance was tested. The LA diameter decreased (38.3 ± 4.1 mm vs. 36.8 ± 3.6 mm, p < 0.001) in the whole study group at 12 months after ablation. The LASRr and LASRcd increased (1.1 ± 0.3 s-¹ vs. 1.3 ± 0.3 s-¹, p < 0.001 and 1.1 ± 0.3 s-¹ vs. 1.2 ± 0.3 s-¹, p < 0.001, respectively) whereas other LA strain parameters remained unchanged in the whole study group at 12 months after ablation. In the analysis of LA function at 12 months after the procedure regarding the mode of ablation, the worsening of parameters reflecting LA compliance was observed in patients with better pre-served baseline values in the CB ablation subgroup. For baseline LAScd >28%, the difference ΔCB - ΔRF was -7.6 (11.7; -3.4), p < 0.001, and for baseline LAScd >16%, ΔCB - ΔRF was -1.8 (-3.2; -0.4), p = 0.014. The traditional Doppler-derived parameter e' showed the same trend-for baseline e' ≥12 cm/s, ΔCB - ΔRF was -1.7 (-2.8; -0.6), p = 0.003. We conclude that worsening of parameters reflecting LA compliance was observed 12 months after CB ablation compared to RF ablation for PAF in patients who underwent a successful procedure and had better-preserved baseline LA function. This might suggest subclinical dysfunction of LA after the CB ablation procedure. The clinical significance of these findings warrants further investigations.

Impact of Percutaneous Mitral Valve Repair on Left Atrial Strain and Atrial Fibrillation Progression

Transcatheter edge-to-edge repair (TEER) currently represents a valuable therapeutic option for patients with severe mitral regurgitation (MR) considered at high surgical risk. Besides symptoms and left ventricular (LV) echocardiographic improvements upon TEER, it has been postulated that left atrial (LA) function plays a prognostic role. The aims of our study were to evaluate LA changes after TEER, measured by two-dimensional speckle-tracking echocardiography analysis (2D-STE), their association with atrial fibrillation (AF) occurrence, and relative arrhythmic burden. We considered in a single-center study 109 patients affected by symptomatic severe MR undergoing TEER from February 2015 to April 2022. By 2D-STE, LA reservoir (R_s), conduct (D_s), and contractile (C_s) strains were assessed along with four-chamber emptying fraction (LAEF-4CH) before, 1, 6, and 12 months following TEER. Statistical analysis for comparison among baseline, and follow-ups after TEER was carried out by ANOVA, MANOVA, and linear regression. Successful TEER significantly improved LV dimensions and LA performances, as indicated by all strain components, and LAEF-4CH after 1 year. Strikingly, a significant reduction in arrhythmic burden was observed, since only one case of subclinical AF detected by a previously implanted cardiac electronic device was found in the cohort of sinus rhythm patients (n = 48) undergone TEER; in addition, ventricular rate was reduced in the AF cohort (n = 61) compared to baseline, together with few episodes of nonsustained ventricular tachycardias (5/61, 8.2%) after MR improvement. Overall, TEER was associated with improved cardiac performance, LA function amelioration, and reduced arrhythmic burden.

Atrial Dysfunction in Significant Atrial Functional Mitral Regurgitation: Phenotypes and Prognostic Implications

BACKGROUND

Atrial functional mitral regurgitation (AFMR) is associated with increased morbidity and mortality. Left atrial (LA) size and function in AFMR are poorly characterized. We aimed to assess LA function by reservoir strain (LASr) and estimated reservoir work (LAWr) and their impact on outcome in AFMR.

METHODS

Consecutive patients at our institution between 2001 and 2019 and with significant (moderate or greater) AFMR were examined. LAWr was estimated as LASr×LA reservoir volume, and patients were grouped by median LASr and LAWr. Outcomes were all-cause death or heart failure hospitalizations.

RESULTS

Five hundred fifteen AFMR patients were followed up for 5 (1-17) years. Patients had previously documented atrial fibrillation (AF; 37%), heart failure with preserved ejection fraction (HFpEF) without AF (24%), or both (HFpEF+AF, 39%). LA volume was largest in AF, while LA function parameters were most impaired in the combined HFpEF+AF group. During follow-up, patients with low LASr or LAWr had higher risk of death (P<0.001) and heart failure hospitalization (P<0.05). In Cox regression analyses, low LASr and LAWr, but not LA volume or left ventricular function, were associated with a higher risk of death (LASr: hazard ratio, 2.3 [95% CI, 1.6-3.5]; LAWr: hazard ratio, 3.4 [95% CI, 2.4-4.9]; both P<0.001) after adjustment for clinical and echocardiographic confounders. Low LASr and LAWr were strongest associated with death in HFpEF and HFpEF+AF.

CONCLUSIONS

LA reservoir function but not LA size is a robust predictor of outcome in significant AFMR. This provides mechanistic insights into the interplay of functional versus geometric LA changes in AFMR.

Pulsed field ablation in patients with complex consecutive atrial tachycardia in conjunction with ultra-high density mapping: Proof of concept

INTRODUCTION

Catheter-ablation (CA) of consecutive left atrial tachycardias (LAT) can be challenging. Pulsed field ablation (PFA) yields a novel nonthermal CA technology for treatment of atrial fibrillation (AF). There is no data regarding PFA of LAT. This study sought to investigate PFA of consecutive LAT following prior CA of AF.

METHODS

Consecutive patients with LAT underwent ultrahigh-density (UHDx) mapping. Subsequent to identification of the AT mechanism, PFA was performed at the assumed critical sites for LAT maintenance. Continuous ablation lines were performed if required and evaluated with pre- and post-PFA HDx-mapping.

RESULTS

Fifteen patients (age 70 ± 10, male 73%) who underwent 3.6 ± 2 prior AF-CA procedures were included. The total mean procedure and fluoroscopy times were 141 ± 43 and 18 ± 10 min, respectively. All 19 of 19 (100%) LAT were successfully ablated with PFA. Two AT located at the right atria required RF-ablation. LAT were identified as localized reentry (n = 1) and macro-reentry LAT (n = 18) and targeted with PFA. All LAT terminated with PFA either to sinus rhythm (9/15) or a secondary AT (6/15 and subsequently to SR); 63% (12/19) terminated with the first PFA-application. All lines (13 roof, 11 anterior, 1 mitral) were blocked. LA-posterior-wall isolation (LAPWI) was successfully achieved when performed (10/10). AF/AT free survival was 80% (12/15) after 153 [88-207] days of follow-up. No procedure-related complications occurred.

CONCLUSION

PFA of consecutive LAT is feasible and safe. Successful creation of ablation lines and LAPWI can be achieved in a short time. PFA may offer the opportunity for effective ablation of atrial arrhythmias beyond AF.

The emerging role of leptin in obesity-associated cardiac fibrosis: evidence and mechanism

Cardiac fibrosis is a hallmark of various cardiovascular diseases, which is quite commonly found in obesity, and may contribute to the increased incidence of heart failure arrhythmias, and sudden cardiac death in obese populations. As an endogenous regulator of adiposity metabolism, body mass, and energy balance, obesity, characterized by increased circulating levels of the adipocyte-derived hormone leptin, is a critical contributor to the pathogenesis of cardiac fibrosis. Although there are some gaps in our knowledge linking leptin and cardiac fibrosis, this review will focus on the interplay between leptin and major effectors involved in the pathogenesis underlying cardiac fibrosis at both cellular and molecular levels based on the current reports. The profibrotic effect of leptin is predominantly mediated by activated cardiac fibroblasts but may also involve cardiomyocytes, endothelial cells, and immune cells. Moreover, a series of molecular signals with a known profibrotic property is closely involved in leptin-induced fibrotic events. A more comprehensive understanding of the underlying mechanisms through which leptin contributes to the pathogenesis of cardiac fibrosis may open up a new avenue for the rapid emergence of a novel therapy for preventing or even reversing obesity-associated cardiac fibrosis.

Safety, Efficacy and Prognostic Benefit of Atrial Fibrillation Ablation in Heart Failure with Preserved Ejection Fraction

Up to 65% of patients with heart failure with preserved ejection fraction (HFpEF) develop AF during the course of the disease. This occurrence is associated with adverse outcomes, including pump failure death. Because AF and HFpEF are mutually reinforcing risk factors, sinus rhythm restoration may represent a disease-modifying intervention. While catheter ablation exhibits acceptable safety and efficacy profiles, no randomised trials have compared AF ablation with medical management in HFpEF. However, catheter ablation has been reported to result in lower natriuretic peptides, lower filling pressures, greater peak cardiac output and improved functional capacity in HFpEF. There is growing evidence that catheter ablation may reduce HFpEF severity, hospitalisation and mortality compared to medical management. Based on indirect evidence, early catheter ablation and minimally extensive atrial injury should be favoured. Hence, individualised ablation strategies stratified by stepwise substrate inducibility provide a logical basis for catheter-based rhythm control in this heterogenous population. Randomised trials are needed for definitive evidence-based guidelines.

Effect of radiofrequency catheter ablation on left atrial structure and function in patients with different types of atrial fibrillation

Radiofrequency catheter ablation (RFCA) is widely used to treat atrial fibrillation (AF), but its effect on left atrial (LA) remodeling in patients with AF is not completely clarified. Few studies have reported the changes in structure and function of the left atrium in patients with different types of AF after RFCA. To analyze the effect of RFCA on the LA structure and function in patients with nonvalvular paroxysmal AF, persistent AF and long-standing persistent AF (LSPAF). RFCA was performed in 180 patients with paroxysmal AF, persistent AF and LSPAF. The changes of LA structure and function in echocardiogram and speckle-tracking echocardiography findings were compared before the procedure, and at 1, 2, 3, 4 weeks, and 2, 3, 6, and 9–12 months after the procedure. There were 60 patients in the paroxysmal AF group, 60 in the persistent AF group and 60 patients in LSPAF group. The pre-procedure LA diameter and volume were smaller in the paroxysmal AF group than persistent AF and LSPAF group. There was no significant change of in the LA structure and function in the paroxysmal AF group within 1 year. In the persistent AF and LSPAF groups, LA structure (anteroposterior diameter, LA volume) significantly decreased, but remained larger than that in paroxysmal AF group. In persistent and LSPAF, function (LA ejection fraction, strain, strain rate) increased significantly within 1 week, then gradually increased. RFCA improved the LA structure and function and resulted in heart reverse remodeling, especially for persistent AF and LSPAF.

The Association Between Subclinical Thyroid Dysfunction and Recurrence of Atrial Fibrillation After Catheter Ablation

Objective

The aim of this study was to evaluate the association between subclinical thyroid dysfunction and the recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA).

Methods

We examined the association between subclinical thyroid dysfunction and the recurrence of AF at a large university-affiliated cardiac arrhythmia center in China. Data were collected from consecutive patients who underwent RFCA for AF, excluding those with a history of hypothyroidism, hyperthyroidism, or ongoing medical treatment for hypothyroidism or hyperthyroidism, biochemically defined overt thyroid disease, and long-term use of amiodarone before admission. The primary end point was the recurrence of AF in a time-to-event analysis. We compared outcomes in patients who had subclinical hyperthyroidism or hypothyroidism with those who had euthyroid state, using a multivariable Cox model with inverse probability weighting and propensity score matching.

Results

In all, 93 patients were excluded from 435 consecutive patients who underwent RFCA for AF. Of the remaining 342 patients for the analysis, the prevalence of subclinical hyperthyroidism and subclinical hypothyroidism were 26 (7.6%) and 41 (12.0%), respectively; during a median follow-up of 489 days, 91 patients (26.6%) developed a primary end point event. In the main analysis of the multivariable Cox model, only subclinical hyperthyroidism [hazard ratio: 3.07, 95% confidence interval (CI): 1.54–6.14] was associated with an increased risk of end point event after adjusting for potential confounders. However, the association between subclinical hypothyroidism and the end point event was not significant (hazard ratio: 0.66, 95% CI: 0.31–1.43). Results were consistent either in multiple sensitivity analyses or across all subgroups of analysis. Compared with individuals with free triiodothyronine (fT3) in the lowest quintile, those with fT3 in the highest quintile had an HR of 2.23 (95% CI: 1.16–4.28) for recurrence of AF. With the increase of thyroid-stimulating hormone (TSH), a reduction in the risk of recurrence of AF was detected in the adjusted model, and the hazard ratio (HR) per standard deviation (SD) increase was 0.82 (95% CI: 0.68–0.98).

Conclusion

In this retrospective cohort study involving patients who underwent RFCA for AF, patients with subclinical hyperthyroidism were associated with a markedly higher prevalence of recurrence of AF, whereas patients with subclinical hypothyroidism had a similar recurrence rate of AF compared to those with the euthyroid state.

Diabetes Mellitus Is an Independent Risk Factor for a Stiff Left Atrial Physiology After Catheter Ablation for Atrial Fibrillation

Background

Scar tissue formation after catheter ablation for atrial fibrillation (AF) may adversely affect the diastolic properties of the left atrium (LA), which can result in a stiff LA physiology in a small proportion of patients. In this study, we aimed to explore the relationship between diabetes mellitus and a stiff LA physiology after AF catheter ablation (AFCA).

Methods

A total of 1,326 patients who underwent de novo AFCA, and baseline and 1-year follow-up echocardiographies were enrolled. After 1:3 propensity score (PS) matching for age, sex, and AF type, we compared 211 patients with DM with 633 patients without DM. A stiff LA physiology was defined as estimated pulmonary arterial pressure increase of >10 mmHg and a right ventricular systolic pressure of >35 mmHg at 1-year follow-up echocardiography. Pulmonary vascular resistance (PVR) was estimated using echocardiographic parameters.

Results

Among the 844 PS-matched patients, a stiff LA physiology was observed in 32 patients (4.1%). The patients with DM showed a higher peak LA pressure (p < 0.001) and greater LA wall stress (p = 0.001) than did those without. A stiff LA physiology was independently associated with DM [Odds ratio (OR) = 2.39, 95% confidence interval (CI) 1.02-5.59, p = 0.045], empirical extra-pulmonary vein LA ablation (OR = 3.14, 95% CI 1.07–9.3, p = 0.038) and the ΔPVR (OR = 1.78, 95% CI 1.37–2.31, p < 0.001). The ΔPVR was independently associated with DM (β = 0.37, 95% CI 0.06-0.67, p = 0.020) and a stiff LA physiology (β = 1.40, 95% CI 0.70–2.10, p < 0.001). During the 38.8 ± 29.3months follow-up, the incidence of the clinical recurrence of AF was significantly higher in the patients with a stiff LA physiology than in those without (log rank p = 0.032).

Conclusion

A stiff LA physiology was independently associated with DM because of the relatively small decrease in the PVR after AFCA in this population. The patients with a stiff LA physiology had worse rhythm outcomes after AFCA than those without.

Echocardiographic Assessment of Atrial Function: From Basic Mechanics to Specific Cardiac Diseases

The left and right atria serve as buffer chambers to control the flow of venous blood for ventricular filling. If an atrium is absent, blood does not flow effectively into the ventricle, leading to venous blood retention and low cardiac output. The importance of atrial function has become increasingly recognized, because left atrial (LA) function contributes to cardiac performance, and loss of LA function is associated with heart failure. LA volume change has been used for LA function assessment in experimental and clinical studies. In conjunction with LA pressure, the LA pressure–volume relationship provides a better understanding of LA mechanics. LA strain measurement by speckle tracking echocardiography was introduced to evaluate three components of LA function as a (booster) pump, reservoir and conduit. Furthermore, increasing evidence supports the theory that LA reservoir strain has prognostic utility in various cardiac diseases. In this review, we summarize LA contribution to maintain cardiac performance by evaluating LA function with echocardiography according to our experiences and previous reports. Furthermore, we discuss LA dysfunction in challenging cardiac diseases of cardiac amyloidosis and adult congenital heart disease.

Endocrine and Mechanical Cardiacfunction Four Months after Radiofrequency Ablation of Atrialfibrillation

Background

Radiofrequency ablation (RFA)is an important treatment option for patients with atrial fibrillation (AF). During RFA, a significant amount of energy is delivered into the left atrium (LA), resulting in considerable LA-injury. The impact of this damage on mechanical and endocrine LA-function, however, is often disregarded.We therefore aimed to evaluate the endocrine- and mechanical function of the heart 4-months after RFA of AF.

Methods

In total 189 patients eligible for RFA of AF were studied. The levels of the N-terminal pro-B-natriuretic peptide (NT-proBNP) and the mid-regional fragment of the N-terminal pro-atrial natriuretic peptide (MR-proANP)were measured. The maximum LAvolume (LAVmax),the LAejection fraction (LAEF) and the LA peak longitudinal strain (PALS), were measured usingtransthoracic echocardiography. The measurements were performed before and 4-months after the intervention.

Results

87 patients had a recurrence during a mean follow-up of 143±36 days.NT-proBNPand MR-proANPdecreased significantly at follow-up. This reduction was greater in patients who did not suffer any recurrence after RFA.The LAVmax decreased significantly, whereasthe PALS only improved in patients who did not suffer from any recurrence. On the other hand, LAEF did not change significantly after RFA of AF.

Conclusions

Despite extensiveablation during RFA of AF, the endocrine function of the heart improved 4-months after the index procedure. Patients with no arrhythmia recurrence showed a more pronounced improvement in their endocrinal function. Mechanically, the LAVmax was reduced, and the LA strain improved significantly.

Clinical Outcomes of low-voltage area-guided left atrial linear ablation for non-paroxysmal atrial fibrillation patients

Background

The therapeutic effect of low-voltage area (LVA)-guided left atrial (LA) linear ablation for non-paroxysmal atrial fibrillation (non-PAF) is uncertain. We aimed to investigate the efficacy of LA linear ablation based on the preexisting LVA and its effects on LA reverse remodeling in non-PAF patients.

Methods

We retrospectively evaluated 145 consecutive patients who underwent radiofrequency catheter ablation for drug-refractory non-PAF. CARTO-guided bipolar voltage mapping was performed in atrial fibrillation (AF). LVA was defined as sites with voltage ≤ 0.5 mV. If circumferential pulmonary vein isolation couldn’t convert AF into sinus rhythm, additional LA linear ablation was performed preferentially at sites within LVA.

Results

After a mean follow-up duration of 48 ± 33 months, 29 of 145 patients had drugs-refractory AF/LA tachycardia recurrence. Low LA emptying fraction, large LA size and high extent of LVA were associated with AF recurrence. There were 136 patients undergoing LA linear ablation. The rate of linear block at the mitral isthmus was significantly higher via LVA-guided than non-LVA-guided linear ablation. Patients undergoing LVA-guided linear ablation had larger LA size and higher extent of LVA, but the long-term AF/LA tachycardia-free survival rate was higher than the non-LVA-guided group. The LA reverse remodeling effects by resuming sinus rhythm were noted even in patients with a diseased left atrium undergoing extensive LA linear ablation.

Conclusions

LVA-guided linear ablation through targeting the arrhythmogenic LVA and reducing LA mass provides a better clinical outcome than non-LVA guided linear ablation, and outweighs the harmful effects of iatrogenic scaring in non-PAF patients.

Levothyroxine Treatment and the Risk of Cardiac Arrhythmias - Focus on the Patient Submitted to Thyroid Surgery

Levothyroxine (LT4) is used to treat frequently encountered endocrinopathies such as thyroid diseases. It is regularly used in clinical (overt) hypothyroidism cases and subclinical (latent) hypothyroidism cases in the last decade. Suppressive LT4 therapy is also part of the medical regimen used to manage thyroid malignancies after a thyroidectomy. LT4 treatment possesses dual effects: substituting new-onset thyroid hormone deficiency and suppressing the local and distant malignancy spreading in cancer. It is the practice to administer LT4 in less-than-high suppressive doses for growth control of thyroid nodules and goiter, even in patients with preserved thyroid function. Despite its approved safety for clinical use, LT4 can sometimes induce side-effects, more often recorded with patients under treatment with LT4 suppressive doses than in unintentionally LT4-overdosed patients. Cardiac arrhythmias and the deterioration of osteoporosis are the most frequently documented side-effects of LT4 therapy. It also lowers the threshold for the onset or aggravation of cardiac arrhythmias for patients with pre-existing heart diseases. To improve the quality of life in LT4-substituted patients, clinicians often prescribe higher doses of LT4 to reach low normal TSH levels to achieve cellular euthyroidism. In such circumstances, the risk of cardiac arrhythmias, particularly atrial fibrillation, increases, and the combined use of LT4 and triiodothyronine further complicates such risk. This review summarizes the relevant available data related to LT4 suppressive treatment and the associated risk of cardiac arrhythmia.

Heart failure with preserved ejection fraction based on aging and comorbidities

Heart failure (HF) with preserved ejection fraction (HFpEF) is a leading cause of hospitalizations and mortality when diagnosed at the age of ≥ 65 years. HFpEF represents multifactorial and multisystemic syndrome and has different pathophysiology and phenotypes. Its diagnosis is difficult to be established based on left ventricular ejection fraction and may benefit from individually tailored approaches, underlying age-related changes and frequent comorbidities. Compared with the rapid development in the treatment of heart failure with reduced ejection fraction, HFpEF presents a great challenge and needs to be addressed considering the failure of HF drugs to improve its outcomes. Further extensive studies on the relationships between HFpEF, aging, and comorbidities in carefully phenotyped HFpEF subgroups may help understand the biology, diagnosis, and treatment of HFpEF. The current review summarized the diagnostic and therapeutic development of HFpEF based on the complex relationships between aging, comorbidities, and HFpEF.

Benefit of ultra-high-density mapping-guided radiofrequency reablation in pulmonary vein isolation non-responders after initial cryoballoon procedure

AIMS

Symptomatic atrial arrhythmias despite complete pulmonary vein isolation (PVI) are common. The purpose was to evaluate ultra-high-density multi-electrode electroanatomical mapping-guided radiofrequency ablation (RFA) in PVI non-responders.

METHODS AND RESULTS

Ultra-high-density multi-electrode electroanatomical mapping-guided RFA in consecutive symptomatic atrial fibrillation (AF) patients after initial cryoballoon PVI was performed. Patients were included if all pulmonary veins (PVs) were still isolated. Radiofrequency targets were atrial tachycardia (AT), extra-PV trigger, and/or substrate. Procedural results and outcome were evaluated. Of 95 patients, 67 (70.5%) with complete PVI were included (70 years, CHA2DS2Vasc 2.9, left atrium 45 mm, persistent AF 45%, AT 45%). The median time to reablation was 26 months. One hundred and seven maps (1.6/patient) and 11.890 ± 9.018 electrograms were acquired in 33 ± 12 min. Twenty-eight percent of the left atrial (LA) wall showed pathological voltage signals, predominantly at the anterior (37%) and septal wall (26%). Atrial tachycardia (49 left, 4 right) were ablated in 35 patients (52%), extra-PV trigger in two patients (3%). One atrioventricular nodal re-entry tachycardia and seven right atrial isthmus ablation (10%) were performed. In 32 patients (48%), no AT was present and substrate-based ablation was performed. Mean LA area ablated was 7 ± 6 cm2 (7%). No major complication occurred. The mean follow-up time was 772 ± 317 days. Freedom from atrial arrhythmia recurrence off antiarrhythmic drugs was 49% at 12 months.

CONCLUSION

Pulmonary vein isolation non-responders are older, mainly suffering from complex atrial arrhythmias. Left atrial substrate is predominantly located at the anterior and septal wall. Ultra-high-density multi-electrode electroanatomical mapping-guided RFA is safe and effective. At 1 year, 5 out of 10 patients were in stable sinus rhythm off antiarrhythmic drugs.

Clinical Phenogroups in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) accounts for more than one-half of patients with heart failure. Effective treatment of HFpEF has not been established, largely because of the complexities and heterogeneity in the phenotypes of HFpEF. Categorizing patients based on clinical and pathophysiologic phenotype may provide more targeted and efficacious therapies. Despite this clinical need, there is no consensus on how to categorize patients with HFpEF into phenogroups. Possible metrics include the presence or absence of specific comorbidities that influence pathophysiology, imaging, hemodynamics, or other biomarkers. This article describes currently recognized phenotypes of HFpEF and potential treatment strategies.

Post Procedural Peak Left Atrial Contraction Strain Predicts Recurrence of Arrhythmia after Catheter Ablation of Atrial Fibrillation

Background

Left atrial (LA) function can be impaired by the atrial fibrillation (AF) ablation and might be associated with the risk of recurrence. We sought to determine whether the post-procedural changes in LA function impact the risk of recurrence following AF ablation.

Methods

We retrospectively reviewed patients who underwent AF ablation between 2009 and 2011 and underwent transthoracic echocardiography before ablation, 1-day and 3-month after ablation. Peak left atrial contraction strain (PACS) and left atrial emptying fraction (LAEF) were evaluated during sinus rhythm and compared across the three time points. The primary endpoint was atrial tachyarrhythmia recurrence after ablation.

Results

A total of 144 patients were enrolled (mean age 61 ± 11 years, 77% male, 46% persistent AF). PACS and LAEF initially decreased 1-day following ablation but partially recovered within 3 months in PAF patients, with a similar trend in the PerAF patients. After median 24 months follow-up, 68 (47%) patients had recurrence. Patients with recurrence had higher PACS_1-day than that in non-recurrence subjects (-10.9 ± 5.0% vs. -13.4 ± 4.7%, p = 0.003). PACS_1-day -12% distinguished recurrence cases with a sensitivity of 67.7% and specificity of 60.5%. The Kaplan–Meier curves showed significant difference in 5-year cumulative probability of recurrence between those with PACS ≥ -12% and PACS < -12% (log rank p < 0.0001). Multivariate regression showed that PACS_1-day was an independent risk factor of arrhythmia recurrence.

Conclusions

Left atrial function deteriorates immediately following AF ablation and partially recovers in 3 months but remains abnormal in the majority of patients. PACS_1-day post procedure predicts arrhythmia recurrence at long-term follow-up.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12947-021-00250-5.

Left Atrial Myopathy in Atrial Fibrillation and Heart Failure: Clinical Implications, Mechanisms, and Therapeutic Targets

PURPOSE OF REVIEW

This review discusses the mechanisms, clinical implications, and treatments of left atrial (LA) myopathy in comorbid atrial fibrillation (AF) and heart failure (HF) across the spectrum of ejection fraction.

RECENT FINDINGS

AF and HF are highly comorbid conditions. Left atrial (LA) myopathy, characterized by impairments in LA structure, function, or electrical conduction, plays a fundamental role in the development of both AF and HF with preserved ejection fraction (AF-HFpEF) along with AF and HF with reduced ejection fraction (AF-HFrEF). While the nature of LA myopathy in AF-HFpEF is unique from that of AF-HFrEF, LA myopathy also leads to progression of both of these conditions. There may be a vulnerable cohort of AF-HF patients who have a disproportionate degree of LA myopathy compared with left ventricular (LV) dysfunction. Further investigations are required to identify therapies to improve LA function in this cohort.

Combination of ablation and left atrial appendage closure as "One-stop" procedure in the treatment of atrial fibrillation: Current status and future perspective

Atrial fibrillation (AF), the most common arrhythmia, is a major cause of stroke and systemic embolism. Left atrial appendage closure (LAAC) has been proved to be noninferior to traditional Vitamin K antagonists (VKAs) as well as novel oral anticoagulants (NOACs), which is becoming an important alternative to prevent stroke in non‐valvular AF. Catheter‐based AF ablation (CA) is recommended to be a standard of care in patients with AF refractory to drug therapy due to a better rhythm control and improvement of life quality than antiarrhythmic drugs. Theoretically, the one‐stop combination with LAAC and CA tends to bring more benefits in patients with AF, as it not only relieves symptoms, but also reduces the risk of stroke significantly. However, several important questions still need to be considered in the combination procedure although quite a few attempts have already been made in clinical practice. This review provides a comprehensive update on the concept, technique, perioperative management, benefits and other critical issues of the “one‐stop” procedure.

Ablation Versus Drug Therapy for Atrial Fibrillation in Heart Failure: Results From the CABANA Trial

BACKGROUND

In patients with heart failure and atrial fibrillation (AF), several clinical trials have reported improved outcomes, including freedom from AF recurrence, quality of life, and survival, with catheter ablation. This article describes the treatment-related outcomes of the AF patients with heart failure enrolled in the CABANA trial (Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation).

METHODS

The CABANA trial randomized 2204 patients with AF who were ≥65 years old or <65 years old with ≥1 risk factor for stroke at 126 sites to ablation with pulmonary vein isolation or drug therapy including rate or rhythm control drugs. Of these, 778 (35%) had New York Heart Association class >II at baseline and form the subject of this article. The CABANA trial's primary end point was a composite of death, disabling stroke, serious bleeding, or cardiac arrest.

RESULTS

Of the 778 patients with heart failure enrolled in CABANA, 378 were assigned to ablation and 400 to drug therapy. Ejection fraction at baseline was available for 571 patients (73.0%), and 9.3% of these had an ejection fraction <40%, whereas 11.7% had ejection fractions between 40% and 50%. In the intention-to-treat analysis, the ablation arm had a 36% relative reduction in the primary composite end point (hazard ratio, 0.64 [95% CI, 0.41-0.99]) and a 43% relative reduction in all-cause mortality (hazard ratio, 0.57 [95% CI, 0.33-0.96]) compared with drug therapy alone over a median follow-up of 48.5 months. AF recurrence was decreased with ablation (hazard ratio, 0.56 [95% CI, 0.42-0.74]). The adjusted mean difference for the AFEQT (Atrial Fibrillation Effect on Quality of Life) summary score averaged over the entire 60-month follow-up was 5.0 points, favoring the ablation arm (95% CI, 2.5-7.4 points), and the MAFSI (Mayo Atrial Fibrillation-Specific Symptom Inventory) frequency score difference was -2.0 points, favoring ablation (95% CI, -2.9 to -1.2).

CONCLUSIONS

In patients with AF enrolled in the CABANA trial who had clinically diagnosed stable heart failure at trial entry, catheter ablation produced clinically important improvements in survival, freedom from AF recurrence, and quality of life relative to drug therapy. These results, obtained in a cohort most of whom had preserved left ventricular function, require independent trial verification. Registration: URL: https://www.clinicaltrials.gov/ct2/show/NCT00911508; Unique identifier: NCT0091150.

Improvement of Maximal Exercise Performance After Catheter-Ablation of Atrial Fibrillation and Its Prognostic Significance for Long-Term Rhythm Outcome

Background

Rhythm control may improve functional capacity in patients with atrial fibrillation (AF). Long‐term exercise tolerance improvement and its prognostic implications following catheter‐ablation (CA) of paroxysmal and nonparoxysmal AF are underreported.

Methods and Results

Consecutive patients underwent cardiopulmonary exercise testing just before and 12 months after their index CA of AF. Follow‐up 24‐hour Holter recordings were obtained at 6‐month intervals post‐CA, and any atrial arrhythmia >30 seconds detected after 3 months postprocedure was considered AF recurrence. Of 110 patients (mean age 57.5±10.6 years, 77.2% males) with paroxysmal AF (n=66) or nonparoxysmal AF (n=44), the 12‐month exercise tolerance improved significantly in those who maintained sinus rhythm during the first 12 months post‐CA (n=96), but not in patients with AF recurrence (n=14). After CA, the 12‐month respiratory exchange ratio at maximal workload significantly increased in patients with paroxysmal AF, whereas those with nonparoxysmal AF significantly reduced their heart rate during the 12‐month cardiopulmonary exercise testing (all P≤0.001). During the follow‐up of 42.8±7.8 months, a total of 29 patients (26.3%) experienced recurrent AF. On multivariate analysis including patients without recurrent AF at 12 months after CA, the extent of work time improvement at follow‐up cardiopulmonary exercise testing was independently associated with the rhythm outcome beyond 12 months postprocedure (hazard ratio of 0.936 [95% CI, 0.894–0.979] for each 10 seconds increase in the work time following ablation, P=0.004).

Conclusions

CA of AF was associated with recovery of exercise intolerance in patients with paroxysmal AF or nonparoxysmal AF. Inability to improve exercise capacity at 12 months post‐CA was an independent risk factor for later AF recurrence.

Atrial Dysfunction in Patients With Heart Failure With Preserved Ejection Fraction and Atrial Fibrillation

BACKGROUND

Paroxysmal and permanent atrial fibrillation (AF) are common in heart failure with preserved ejection fraction (HFpEF).

OBJECTIVES

This study sought to determine the implications of left atrial (LA) myopathy and dysrhythmia across the spectrum of AF burden in HFpEF.

METHODS

Consecutive patients with HFpEF (n = 285) and control subjects (n = 146) underwent invasive exercise testing and echocardiographic assessment of cardiac structure, function, and pericardial restraint.

RESULTS

Patients with HFpEF were categorized into stages of AF progression: 181 (65%) had no history of AF, 49 (18%) had paroxysmal AF, and 48 (17%) had permanent AF. Patients with permanent AF were more congested with greater pulmonary vascular disease and lower cardiac output. LA volumes increased, while LA compliance, LA reservoir strain, and right ventricular function decreased with increasing AF burden. The presence of permanent AF was characterized by a distinct pathophysiology, with greater total heart volume caused by atrial dilatation, leading to elevated filling pressures through heightened pericardial restraint. Survival decreased with increasing AF burden. Ten-year progression to permanent AF was common, particularly in paroxysmal AF (52%), and the likelihood of AF progression increased with higher AF stage, poorer LA compliance, and lower LA strain.

CONCLUSIONS

LA compliance and mechanics progressively decline with increasing AF burden in HFpEF, increasing risk for new onset AF and progressive AF. These changes promote development of a unique phenotype of HFpEF characterized by heightened ventricular interaction, right heart failure, and worsening pulmonary vascular disease. Further study is required to identify therapeutic interventions targeting LA myopathy to improve outcomes in HFpEF.

Pro-Arrhythmic Signaling of Thyroid Hormones and Its Relevance in Subclinical Hyperthyroidism

A perennial task is to prevent the occurrence and/or recurrence of most frequent or life-threatening cardiac arrhythmias such as atrial fibrillation (AF) and ventricular fibrillation (VF). VF may be lethal in cases without an implantable cardioverter defibrillator or with failure of this device. Incidences of AF, even the asymptomatic ones, jeopardize the patient's life due to its complication, notably the high risk of embolic stroke. Therefore, there has been a growing interest in subclinical AF screening and searching for novel electrophysiological and molecular markers. Considering the worldwide increase in cases of thyroid dysfunction and diseases, including thyroid carcinoma, we aimed to explore the implication of thyroid hormones in pro-arrhythmic signaling in the pathophysiological setting. The present review provides updated information about the impact of altered thyroid status on both the occurrence and recurrence of cardiac arrhythmias, predominantly AF. Moreover, it emphasizes the importance of both thyroid status monitoring and AF screening in the general population, as well as in patients with thyroid dysfunction and malignancies. Real-world data on early AF identification in relation to thyroid function are scarce. Even though symptomatic AF is rare in patients with thyroid malignancies, who are under thyroid suppressive therapy, clinicians should be aware of potential interaction with asymptomatic AF. It may prevent adverse consequences and improve the quality of life. This issue may be challenging for an updated registry of AF in clinical practice. Thyroid hormones should be considered a biomarker for cardiac arrhythmias screening and their tailored management because of their multifaceted cellular actions.

Characterization, Pathogenesis, and Clinical Implications of Inflammation-Related Atrial Myopathy as an Important Cause of Atrial Fibrillation

Historically, atrial fibrillation has been observed in clinical settings of prolonged hemodynamic stress, eg, hypertension and valvular heart disease. However, recently, the most prominent precedents to atrial fibrillation are metabolic diseases that are associated with adipose tissue inflammation (ie, obesity and diabetes mellitus) and systemic inflammatory disorders (ie, rheumatoid arthritis and psoriasis). These patients typically have little evidence of left ventricular hypertrophy or dilatation; instead, imaging reveals abnormalities of the structure or function of the atria, particularly the left atrium, indicative of an atrial myopathy. The left atrium is enlarged, fibrotic and noncompliant, potentially because the predisposing disorder leads to an expansion of epicardial adipose tissue, which transmits proinflammatory mediators to the underlying left atrium. The development of an atrial myopathy not only leads to atrial fibrillation, but also contributes to pulmonary venous hypertension and systemic thromboembolism. These mechanisms explain why disorders of systemic or adipose tissue inflammation are accompanied an increased risk of atrial fibrillation, abnormalities of left atrium geometry and an enhanced risk of stroke. The risk of stroke exceeds that predicted by conventional cardiovascular risk factors or thromboembolism risk scores used to guide the use of anticoagulation, but it is strongly linked to clinical evidence and biomarkers of systemic inflammation.

Atrial Cardiomyopathy: An Unexplored Limb of Virchow's Triad for AF Stroke Prophylaxis

The most dreaded complication of atrial fibrillation is stroke, and 70–80% of patients with AF-related stroke die or become disabled. The mechanisms of thromboembolism in AF are multifactorial, with evidence demonstrating that all three criteria of Virchow's triad are satisfied in AF: abnormal stasis of blood, endothelial damage, and hypercoagulability. Mechanistic insights into the latter two limbs have resulted in effective stroke prophylactic therapies (left atrial appendage occlusion and oral anticoagulants); however, despite these advances, there remains an excess of stroke in the AF population that may be due, in part, to a lack of mechanistic understanding of atrial hypocontractility resulting in abnormal stasis of blood within the atrium. These observations support the emerging concept of atrial cardiomyopathy as a cause of stroke. In this Review, we evaluate molecular, translational, and clinical evidence for atrial cardiomyopathy as a cause for stroke from AF, and present a rationale for further investigation of this largely unaddressed limb of Virchow's triad in AF.

Do most patients with obesity or type 2 diabetes, and atrial fibrillation, also have undiagnosed heart failure? A critical conceptual framework for understanding mechanisms and improving diagnosis and treatment

Obesity and diabetes can lead to heart failure with preserved ejection fraction (HFpEF), potentially because they both cause expansion and inflammation of epicardial adipose tissue and thus lead to microvascular dysfunction and fibrosis of the underlying left ventricle. The same process also causes an atrial myopathy, which is clinically evident as atrial fibrillation (AF); thus, AF may be the first manifestation of HFpEF. Many patients with apparently isolated AF have latent HFpEF or subsequently develop HFpEF. Most patients with obesity or diabetes who have AF and exercise intolerance have increased left atrial pressures at rest or during exercise, even in the absence of diagnosed HFpEF. Among patients with AF, those who also have latent HFpEF have increased risk for systemic thromboembolism and death. The identification of HFpEF in patients with obesity or diabetes alters the risk-to-benefit relationship of commonly prescribed treatments. Bariatric surgery and statins can ameliorate AF and reduce the risk for HFpEF. Conversely, antihyperglycaemic drugs that promote adipogenesis or cause sodium retention (insulin and thiazolidinediones) may increase the risk for heart failure in patients with an underlying ventricular myopathy. Patients with obesity and diabetes who undergo catheter ablation for AF are at increased risk for AF recurrence and for post-ablation increases in pulmonary venous pressures and worsening heart failure, especially if HFpEF coexists. Therefore, AF may be the earliest indicator of HFpEF in patients with obesity or type 2 diabetes, and recognition of HFpEF alters the management of these patients.

When Hindsight Is 20/20

Scarring from atrial ablation carries a risk of developing stiff left atrium syndrome, which can mimic mitral valve disease. We present a case of a 73-year-old man whose stiff left atrium syndrome came to light after percutaneous mitral valve repair. (Level of Difficulty: Intermediate.)

Disease-treatment interactions in the management of patients with obesity and diabetes who have atrial fibrillation: the potential mediating influence of epicardial adipose tissue

Both obesity and type 2 diabetes are important risk factors for atrial fibrillation (AF), possibly because they both cause an expansion of epicardial adipose tissue, which is the source of proinflammatory adipocytokines that can lead to microvascular dysfunction and fibrosis of the underlying myocardium. If the derangement of epicardial fat adjoins the left atrium, the result is an atrial myopathy, which is clinically manifest as AF. In patients with AF, there is a close relationship between epicardial fat volume and the severity of electrophysiological abnormalities in the adjacent myocardial tissues, and epicardial fat mass predicts AF in the general population. The expansion of epicardial adipose tissue in obesity and type 2 diabetes may also affect the left ventricle, impairing its distensibility and leading to heart failure with a preserved ejection fraction (HFpEF). Patients with obesity or type 2 diabetes with AF often have HFpEF, but the diagnosis may be missed, if dyspnea is attributed to increased body mass or to the arrhythmia. The expected response to the treatment for obesity, diabetes or AF may be influenced by their effects on epicardial inflammation and the underlying atrial and ventricular myopathy. Bariatric surgery and metformin reduce epicardial fat mass and ameliorate AF, whereas insulin promotes adipogenesis and cardiac fibrosis, and its use is accompanied by an increased risk of AF. Rate control strategies for AF may impair exercise tolerance, because they allow for greater time for ventricular filling in patients who cannot tolerate volume loading because of cardiac fibrosis and HFpEF. At the same time, both obesity and diabetes decrease the expected success rate of rhythm control strategies for AF (e.g., electrical cardioversion or catheter ablation), because increased epicardial adipose tissue volumes and cardiac fibrosis are important determinants of AF recurrence following these procedures.

A Compelling Case for Less Aggressive Arrhythmia Management in Patients With Chronic Heart Failure and Long-Standing Atrial Fibrillation

BACKGROUND AND METHODS

Atrial fibrillation (AF) is common in chronic heart failure, and some have advocated intensive rate and/or rhythm control strategies for these patients. However, the loss of atrial systole and irregularity of the ventricular response has not been shown to contribute to the progression of heart failure, and the presence or rate of long-standing AF in patients with chronic heart failure does not have prognostic significance.

RESULTS

In randomized clinical trials, pharmacological rhythm control has not been shown to be superior to rate-control in influencing long-term outcomes, but the use of membrane-active antiarrhythmic drugs can increase the risk of both pump failure and arrhythmic deaths in patients with heart failure. Additionally, intensive efforts to slow the ventricular rate in AF can potentially cause clinically inapparent bradyarrhythmias, which can trigger rate-dependent lethal rhythm disturbances or hemodynamic abnormalities. In patients with AF, a more stringent approach to rate control (target rate <80/min) is not superior to a more lenient strategy (target rate <110/min) on the risk of major events. Little is known about the effects of catheter ablation of long-standing AF in established heart failure, particularly in patients with a preserved or a meaningfully reduced ejection fraction, but ablation can add to the fibrotic burden of the left atrium and impair its capacitance functions.

CONCLUSIONS

For all of these reasons, the management of heart failure and long-standing AF should be primarily directed to slowing of the progression of their underlying cardiomyopathic process rather than the treatment of the arrhythmia. In addition, patients should receive long-term oral anticoagulation with non-vitamin K-antagonist oral anticoagulants to reduce the risk of thromboembolic events. The utility of intensive rate and rhythm control interventions for long-standing AF in patients with established heart failure requires further study.

Heart Failure Differentially Modulates Natural (Sinoatrial Node) and Ectopic (Pulmonary Veins) Pacemakers: Mechanism and Therapeutic Implication for Atrial Fibrillation

Heart failure (HF) frequently coexists with atrial fibrillation (AF) and dysfunction of the sinoatrial node (SAN), the natural pacemaker. HF is associated with chronic adrenergic stimulation, neurohormonal activation, abnormal intracellular calcium handling, elevated cardiac filling pressure and atrial stretch, and fibrosis. Pulmonary veins (PVs), which are the points of onset of ectopic electrical activity, are the most crucial AF triggers. A crosstalk between the SAN and PVs determines PV arrhythmogenesis. HF has different effects on SAN and PV electrophysiological characteristics, which critically modulate the development of AF and sick sinus syndrome. This review provides updates to improve our current understanding of the effects of HF in the electrical activity of the SAN and PVs as well as therapeutic implications for AF.