Circulating adipose tissue proteins involved in atrial fibrillation: An explorative scoping review

Obesity increases the risk of atrial fibrillation (AF), potentially through proteins secreted by adipose tissue (AT) that affect atrial electrical and structural remodeling. We aim to give a comprehensive overview of circulating AT proteins involved in inflammation and fibrosis, that are associated with prevalent AF (paroxysmal or persistent) and the risk on developing new-onset AF. These include adipokines, defined as proteins enriched in AT as adiponectin, but also proteins less specific to AT. We systematically performed an explorative search for studies reporting associations between proteins secreted from cells residing in the AT and AF, and additionally assessed the effect of obesity on these proteins by a secondary search. The AT proteins involved in inflammation were mostly increased in patients with prevalent and new-onset AF, and with obesity, while the AT enriched adipokines were mostly not associated with AF. This review provides insight into circulating adipose tissue proteins involved in AF substrate formation.

MicroRNAs in extracellular vesicles released from epicardial adipose tissue promote arrhythmogenic conduction slowing

Background

Patients with excess epicardial adipose tissue (EAT) are at increased risk of developing cardiac arrhythmias. EAT promotes arrhythmias by depolarizing the resting membrane of cardiomyocytes, which slows down conduction and facilitates re-entrant arrhythmias. We hypothesized that EAT slows conduction by secreting extracellular vesicles (EVs) and their microRNA (miRNA) cargo.

Objective

We aimed to determine the role of EAT-derived EVs and their miRNA cargo in conduction slowing.

Methods

EAT and subcutaneous adipose tissue (SAT) were collected from patients with atrial fibrillation. Adipose tissue explants were incubated in culture medium and secretome was collected. The numbers of EVs in the EAT and SAT secretome were measured by calibrated flow cytometry. EVs in the EAT secretome were isolated by size exclusion chromatography and miRNAs were sequenced. Pathway analysis was performed to predict candidates involved in cardiac electrophysiology. The candidates were validated in the EAT and SAT by quantitative real-time polymerase chain reaction. Finally, miRNA candidates were overexpressed in neonatal rat ventricular myocytes.

Results

The EV concentration was higher in the EAT secretome than in the SAT and control secretomes. miRNA sequencing of EAT-derived EVs detected a total of 824 miRNAs. Pathway analysis led to the identification of 7 miRNAs potentially involved in regulation of cardiac resting membrane potential. Validation of those miRNA candidates showed that they were all expressed in EAT, and that miR-1-3p and miR-133a-3p were upregulated in EAT in comparison with SAT. Overexpression of miR-1-3p and miR-133a-3p in neonatal rat ventricular myocytes led to conduction slowing and reduced Kcnj2 and Kcnj12 expression.

Conclusion

miR-1-3p and miR-133a-3p are potential mediators of EAT arrhythmogenicity.

Atrial epicardial adipose tissue abundantly secretes myeloperoxidase and activates atrial fibroblasts in patients with atrial fibrillation

BACKGROUND

Epicardial adipose tissue (EAT) secretome induces fibrosis. Fibrosis, primarily extracellular matrix (ECM) produced by fibroblasts, creates a substrate for atrial fibrillation (AF). Whether the EAT secretome from patients with AF activates human atrial fibroblasts and through which components, remains unexplored.

RESEARCH AIMS

(a) To investigate if the EAT secretome from patients with versus without AF increases ECM production in atrial fibroblasts. (b) To identify profibrotic proteins and processes in the EAT secretome and EAT from patients with, who will develop (future onset), and without AF.

METHODS

Atrial EAT was obtainded during thoracoscopic ablation (AF, n = 20), or open-heart surgery (future onset and non-AF, n = 35). ECM gene expression of human atrial fibroblasts exposed to the EAT secretome and the proteomes of EAT secretome and EAT were assessed in patients with and without AF. Myeloperoxidase and neutrophil extracellular traps (NETs) were assessed immunohistochemically in patients with paroxysmal, persistent, future onset, and those who remain free of AF (non-AF).

RESULTS

The expression of COL1A1 and FN1 in fibroblasts exposed to secretome from patients with AF was 3.7 and 4.7 times higher than in patients without AF (p < 0.05). Myeloperoxidase was the most increased protein in the EAT secretome and EAT from patients with versus without AF (FC 18.07 and 21.57, p < 0.005), as was the gene-set neutrophil degranulation. Immunohistochemically, myeloperoxidase was highest in persistent (FC 13.3, p < 0.0001) and increased in future onset AF (FC 2.4, p = 0.02) versus non-AF. Myeloperoxidase aggregated subepicardially and around fibrofatty infiltrates. NETs were increased in patients with persistent versus non-AF (p = 0.03).

CONCLUSION

In AF, the EAT secretome induces ECM gene expression in atrial fibroblasts and contains abundant myeloperoxidase. EAT myeloperoxidase was increased prior to AF onset, and both myeloperoxidase and NETs were highest in persistent AF, highlighting the role of EAT neutrophils in the pathophysiology of AF.

A failed catheter ablation of atrial fibrillation is associated with more advanced remodeling and reduced efficacy of further thoracoscopic ablation

INTRODUCTION AND OBJECTIVES

Recent observations suggest that patients with a previous failed catheter ablation have an increased risk of atrial fibrillation (AF) recurrence after subsequent thoracoscopic AF ablation. We assessed the risk of AF recurrence in patients with a previous failed catheter ablation undergoing thoracoscopic ablation.

METHODS

We included patients from 3 medical centers. To correct for potential heterogeneity, we performed propensity matching to compare AF freedom (freedom from any atrial tachyarrhythmia> 30 s during 1-year follow-up). Left atrial appendage tissue was analyzed for collagen distribution.

RESULTS

A total of 705 patients were included, and 183 had a previous failed catheter ablation. These patients had fewer risk factors for AF recurrence than ablation naïve controls: smaller indexed left atrial volume (40.9± 12.5 vs 43.0±12.5 mL/m², P=.048), less congestive heart failure (1.5% vs 8.9%, P=.001), and less persistent AF (52.2% vs 60.3%, P=.067). However, AF history duration was longer in patients with a previous failed catheter ablation (6.5 [4-10.5] vs 4 [2-8] years; P<.001). In propensity matched analysis, patients with a failed catheter ablation were at a 68% higher AF recurrence risk (OR, 1.68; 95%CI, 1.20-2.15; P=.034). AF freedom was 61.1% in patients with a previous failed catheter ablation vs 72.5% in ablation naïve matched controls. On histology of the left atrial appendage (n=198), patients with a failed catheter ablation had a higher density of collagen fibers.

CONCLUSIONS

Patients with a prior failed catheter ablation had fewer risk factors for AF recurrence but more frequently had AF recurrence after thoracoscopic AF ablation than ablation naïve patients. This may in part be explained by more progressed, subclinical, atrial fibrosis formation.

Atrial inflammation and microvascular thrombogenicity are increased in deceased COVID-19 patients

BACKGROUND

Histopathological studies have shown inflammation, cardiomyocyte injury, and microvascular thrombosis in the ventricular myocardium of patients with coronavirus disease 2019 (COVID-19). However, although atrial dysfunction is common in COVID-19, little is known about histopathological changes in the atria of the heart. We therefore analyzed inflammation, cardiomyocyte injury, and microvascular thrombogenicity in the atria of deceased patients with COVID-19.

METHODS

Atrial tissue was obtained from autopsied COVID-19 (n=16) patients and control patients (n=10) and analyzed using immunohistochemistry. The infiltration of CD45+ leukocytes, CD3+ T lymphocytes, CD68+ macrophages, MPO+ neutrophils, and Tryptase+ mast cells were quantified as well as cardiomyocyte damage and microvascular thrombosis. In addition, Tissue Factor (TF) and Factor XII (FXII) were quantified as markers of microvascular thrombogenicity.

RESULTS

The numbers of lymphocytes, macrophages, and neutrophils were significantly increased in the atrial myocardium and epicardial atrial adipose tissue of COVID-19 patients compared with the control group. This was accompanied by dispersed cardiomyocyte injury, the occasional presence of microvascular thrombosis, and an increased presence of TF and FXII in the microvascular endothelium.

CONCLUSIONS

Severe COVID-19 induces inflammation, cardiomyocyte injury, and microvascular thrombosis in the atria of the heart.

Women Have More Recurrences of Atrial Fibrillation than Men after Thoracoscopic Ablation and Suffer More from Established Risk Factors

Introduction. Atrial fibrillation (AF) is more prevalent in men than in women. However, women with AF are more symptomatic, have a worse quality of life, a higher stroke risk and may therefore benefit most from ablation. In this study we aim to identify the risk of recurrent AF after thoracoscopic ablation, and assess the differential impact of the risk factors for recurrence between women and men. Method. This is a single center cohort study, including patients undergoing thoracoscopic ablation for advanced AF between 2008 and 2019. All patients were clinically followed up for two years with quarterly 24 h Holter monitoring and ECGs for the detection of recurrent AF. Left atrial appendage (LAA) tissue was collected for collagen analysis. Results. We included 571 patients, of whom 143 (25%) were women. Women were older than men (63 ± 8.3 y vs. 59 ± 8.5, p < 0.001), but had fewer cardiovascular risk factors, myocardial infarctions (1.4% vs. 6.5%, p = 0.03) and, in particular, vascular disease (7.0% vs. 16.1%, p = 0.01). Women suffered more from AF recurrence, driven by more atrial tachycardias, and sex was an independent risk factor for recurrence (HR1.41 [1.04–1.91], p = 0.028]). The presence of vascular disease was associated with an increased risk for AF recurrence in women, but not in men. In LAA histology, women had more collagen than men, as had patients with persistent compared to paroxysmal AF. Conclusion. Women had 15% more recurrences, driven by more atrial tachycardias, which may be explained by a more fibrotic atrial substrate. What’s new? Women undergoing thoracoscopic AF ablation have a higher risk of recurrent AF, driven by more atrial tachycardias. Among patients with left atrial enlargement or persistent AF, women have worse outcomes than men. Vascular disease was a risk factor for recurrence in women, but not in men. In a histopathologic analysis of the left atrial appendage, women had more collagen than men, as had patients with persistent compared to paroxysmal AF.

Secretome of atrial epicardial adipose tissue facilitates reentrant arrhythmias by myocardial remodeling

BACKGROUND

Epicardial adipose tissue (EAT) accumulation is associated with cardiac arrhythmias. The effect of EAT secretome (EATs) on cardiac electrophysiology remains largely unknown.

OBJECTIVE

The purpose of this study was to investigate the arrhythmogenicity of EATs and its underlying molecular and electrophysiological mechanisms.

METHODS

We collected atrial EAT and subcutaneous adipose tissue (SAT) from 30 patients with atrial fibrillation (AF), and EAT from 3 donors without AF. The secretome was collected after a 24-hour incubation of the adipose tissue explants. We cultured neonatal rat ventricular myocytes (NRVMs) with EATs, subcutaneous adipose tissue secretome (SATs), and cardiomyocytes conditioned medium (CCM) for 72 hours. We implemented the electrophysiological changes observed after EATs incubation into a model of human left atrium and tested arrhythmia inducibility.

RESULTS

Incubation of NRVMs with EATs decreased expression of the potassium channel subunit Kcnj2 by 26% and correspondingly reduced the inward rectifier K+ current IK1 by 35% compared to incubation with CCM, resulting in a depolarized resting membrane of cardiomyocytes. EATs decreased expression of connexin43 (29% mRNA, 46% protein) in comparison to CCM. Cells incubated with SATs showed no significant differences in Kcnj2 or Gja1 expression in comparison to CCM, and their resting potential was not depolarized. Cardiomyocytes incubated with EATs showed reduced conduction velocity and increased conduction heterogeneity compared to SATs and CCM. Computer modeling of human left atrium revealed that the electrophysiological changes induced by EATs promote sustained reentrant arrhythmias if EAT partially covers the myocardium.

CONCLUSION

EAT slows conduction, depolarizes the resting potential, alters electrical cell-cell coupling, and facilitates reentrant arrhythmias.

Left atrial strain and recurrence of atrial fibrillation after thoracoscopic surgical ablation: a subanalysis of the AFACT study

To assess transthoracic echocardiographic (TTE) left atrial (LA) strain parameters and their association with atrial fibrillation (AF) recurrence after thoracoscopic surgical ablation (SA) in patients in sinus rhythm (SR) or in AF at baseline. Patients participating in the Atrial Fibrillation Ablation and Autonomic Modulation via Thoracoscopic Surgery trial were included. All patients underwent thoracoscopic pulmonary vein isolation with LA appendage exclusion and were randomized to ganglion plexus (GP) or no GP ablation. In TTEs performed before surgery, LA strain and mechanical dispersion (MD) of the LA reservoir and conduit phase in all patients, and of the contraction phase in patients in SR were obtained. Recurrence of AF was defined as any documented atrial tachyarrhythmia lasting > 30 s during one year of follow-up. Two hundred and four patients (58.6 ± 7.8 years, 73% male, 57% persistent AF) were included. At baseline TTE 121 (59%) were in SR and 83 (41%) had AF. Patients with AF recurrence had lower LA strain of the reservoir phase (13.0% vs. 16.6%; p =  < 0.001) and a less decrease in strain of the conduit phase (−9.0% vs. −11.8%; p = 0.006), regardless of rhythm. MD of the conduit phase was larger in patients with AF recurrence (79.4 vs. 43.5 ms; p = 0.012). Multivariate cox regression analysis demonstrated solely an association between LA strain of the reservoir phase and AF recurrence in patients in SR (HR 0.95, p = 0.046) or with AF (HR 0.90, p = 0.038). A reduction in LA strain of the reservoir phase prior to SA predicts recurrence of AF in both patients with SR or AF. Left atrial strain assessment may therefore add to a better patient selection for SA.

Change in health related quality of life is different in obese versus non-obese patients with atrial fibrillation after thoracoscopic ablation

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): Received research grants (through institution) from Atricure Inc, Bayer, Boston Scientific, Daiichi Sankyo, Johnson&Johnson, Medtronic

Received honoraria/speaker/consultancy fees from Abbott, AtriaN Medical, Atricure Inc, Bayer, Biotronik, CVOI, Daiichi Sankyo, IPP Med, Itreas, Medtronic, Novartis, Servier

Background

Obesity is an important risk factor for atrial fibrillation (AF), and negatively affects health-related quality of life (QoL) and treatment efficacy. The impact of obesity on the improvement of QoL and on AF recurrence in patients undergoing thoracoscopic AF ablation is unknown.

Purpose

To assess the change in QoL and the risk of AF recurrence in obese and non-obese patients with atrial fibrillation undergoing thoracoscopic ablation

Methods

Patients undergoing thoracoscopic AF ablation were prospectively included. Holters were performed before and at 3, 6, 9 and 12 months after the procedure. AF recurrence was defined as any atrial tachyarrhythmia episode &gt;30 seconds during one year of follow-up. QoL and AF recurrence rate were assessed for normal weight (BMI ≤ 24,9 kg/m2), overweight (25,0 – 29,9 kg/m2) and obese (≥ 30,0 kg/m2) patients. QoL was measured by the Short Form 36 questionnaire at baseline and at one year follow-up.

Results

Four hundred and eight patients were included for analysis. Six out of eight QoL domains scored lower in obese versus non-obese patients before the procedure. In all patients, six out of eight domains increased after the procedure (p&lt;0.01 for most domains). Obese patients showed a larger improvement of emotional related QoL (p=0.01) and a trend towards a larger improvement of mental QoL (p=0.07), while physical QoL increased similarly to non-obese patients (figure). In obese patients, QoL increased similarly for those with and without AF recurrence (p=0.78), whereas in non-obese patients, AF recurrence was associated with less improvement in mental QoL. AF recurrence at 1-year was similar in all groups (normal weight 72.4%, overweight 68%, obese 70.4%, p=0.692).

Conclusion

After thoracoscopic ablation, obese patients have a similar AF freedom rate as non-obese patients, but a greater improvement in mental quality of life, irrespective of AF recurrence status, after thoracoscopic ablation.

Does left atrial epicardial conduction time reflect atrial fibrosis and the risk of atrial fibrillation recurrence after thoracoscopic ablation? Post hoc analysis of the AFACT trial

OBJECTIVES

To determine the association between left atrial epicardial conduction time (LAECT), fibrosis and atrial fibrillation (AF) recurrence after thoracoscopic surgical ablation of persistent AF.

SETTING

Single tertiary care centre in the Netherlands.

PARTICIPANTS

Patients with persistent AF from the randomised Atrial Fibrillation Ablation and Autonomic Modulation via Thoracoscopic Surgery (AFACT)-trial were included. Patients eligible for thoracoscopic AF ablation were included, full inclusion and exclusion criteria were previously published. All patients underwent thoracoscopic ablation, encompassing pulmonary vein isolation with an additional roof and trigone lesion. In patients with conduction block across the roof and trigone lesion, LAECT was measured. LAECT was defined as the time to local activation at one side of the roofline on pacing from the opposite side. Collagen fibre density was quantified from left atrial appendage histology.

OUTCOME MEASURES

Primary outcome: AF recurrence during 2 years of follow-up.

RESULTS

121 patients were included, of whom 35(29%) were women, age was 60.4±7.8 and 51% (62) had at least one AF recurrence during 2 years of follow-up. LAECT was longer in patients with versus without AF recurrence (182±43 ms vs 147±29 ms, p<0.001). LAECT was longer in older patients, in patients with a higher body mass index (BMI) and in patients using class IC antiarrhythmic drugs. LAECT was shorter in patients with higher collagen fibre density. A previously failed catheter ablation, LAECT and BMI were independently associated with AF recurrence.

CONCLUSION

LAECT is correlated with collagen fibre density and BMI and is independently associated with AF recurrence in patients with persistent AF. In these patients, LAECT appears to reflect substrate characteristics beyond clinical AF type and left atrial volume.

TRIAL REGISTRATION NUMBER

NCT01091389.

Extracellular matrix remodeling precedes atrial fibrillation: Results of the PREDICT-AF trial

BACKGROUND

To which extent atrial remodeling occurs before atrial fibrillation (AF) is unknown.

OBJECTIVE

The PREventive left atrial appenDage resection for the predICtion of fuTure Atrial Fibrillation (PREDICT-AF) study investigated such subclinical remodeling, which may be used for risk stratification and AF prevention.

METHODS

Patients (N = 150) without a history of AF with a CHA₂DS₂-VASc score of ≥2 at an increased risk of developing AF were included. The left atrial appendage was excised and blood samples were collected during elective cardiothoracic surgery for biomarker discovery. Participants were followed for 2 years with Holter monitoring to determine any atrial tachyarrhythmia after a 50-day blanking period.

RESULTS

Eighteen patients (12%) developed incident AF, which was associated with increased tissue gene expression of collagen I (COL1A1), collagen III (COL3A1), and collagen VIII (COL8A2), tenascin-C (TNC), thrombospondin-2 (THBS2), and biglycan (BGN). Furthermore, the fibroblast activating endothelin-1 (EDN1) and sodium voltage-gated channel β subunit 2 (SCN2B) were associated with incident AF whereas the Kir2.1 channel (KCNJ2) tended to downregulate. The plasma levels of COL8A2 and TNC correlated with tissue expression and predicted incident AF. A gene panel including tissue KCNJ2, COL1A1, COL8A2, and EDN1 outperformed clinical prediction models in discriminating incident AF.

CONCLUSION

The PREDICT-AF study demonstrates that atrial remodeling occurs long before incident AF and implies future potential for early patient identification and therapies to prevent AF (ClinicalTrials.gov identifier NCT03130985).

P3500The primary cilium, a sensory apparatus of cells regulates the profibrotic capacity of fibroblasts in atrial fibrillation

Background

Atrial fibrosis is a hallmark of atrial fibrillation (AF) and serves as an important arrhythmogenic substrate. It is formed by fibroblasts in response to tissue dyshomeostasis induced by multiple factors such as ageing, hypertension and inflammation. How fibroblasts phenotypically transform into an active form with enhanced profibrotic capacity in AF pathophysiology remains elusive. The primary cilium is an antenna-like small organelle, that function as a sensor to transduce external stimuli to intracellular signaling thereby potentially mediating the fibroblast's profibrotic capacity. Their involvement in AF pathophysiology is not known.

Objective

To explore the role of fibroblasts' primary cilium in the formation of the atrial fibrosis in AF.

Methods

Left atrial appendages (LAA) were obtained from persistent AF patients (AF: n=10) and patients without AF undergoing cardiac surgery (control: n=10). Primary cilia were immunostained with anti-acetylated a-tubulin in cryosections of the LAA. The loss of cilia in fibroblasts isolated from fresh LAA (AF: n=3, control: n=3) was induced by RNAi targeting IFT88, an essential factor for cilia formation. Gene expression and protein levels in LAA were quantified by qPCR and western blot, respectively (AF: n=20, control: n=20).

Results

The ratio of fibroblasts with primary cilium was significantly decreased in LAA of AF cohort (AF: 14.7%±4.6 vs control: 25.9%±3.6, p<0.01). Correspondingly, the protein levels of acetylated a-tubulin, an exclusive component of cilia, were significantly decreased both in whole LAA and fibroblast fraction of AF cohort compared to control (p<0.05). The loss of primary cilia induced by RNAi in fibroblasts resulted in increased differentiation of fibroblasts into myofibroblasts and the expression of extracellular matrix genes in response to TGF -b1.

Primary cilium is disassembled along with degradation of acetylated a-tubulin by HDAC6. Indeed, a negative correlation between the protein levels of acetylated a-tubulin and HDAC6 were observed in the LAA of AF cohort (p<0.05) but not in control. Furthermore, the gene expression of AURKA and HEF1, upstream activators of HDAC6, was increased by 1.5-fold (p=0.09) and 3-fold (p<0.001), respectively, in the LAA of AF cohort compared to control.

Conclusion

The formation of primary cilia in fibroblasts is actively suppressed in AF via HEF1/AURKA/HDAC6 cascade, which in turn enhances the profibrotic response of fibroblasts. This study provides an innovative paradigm for fibrosis formation in AF, and implicates that the primary cilium of fibroblasts potentially become a novel therapeutic target to treat the AF substrate.

P1837HFpEF reverses in more than a quarter of patients after thoracoscopic AF ablation

Purpose

To evaluate the proportion of patients in whom parameters that define the diagnosis of HFpEF and HFmrEF persist versus normalize upon elimination of AF.

Background

Atrial fibrillation (AF) and heart failure with preserved or mid-range ejection fraction (HFpEF or HFmrEF) concur in many patients. Distinction between these two diagnoses remains challenging as one can cause or exacerbate the other. Adequate patient selection for invasive AF treatment is crucial to improve rhythm outcome.

Methods

Patients underwent thoracoscopic ablation, consisting of pulmonary vein isolation (PVI) alone or PVI with additional lines in the case of persistent AF. Patients were prospectively followed-up. HFmrEF or HFpEF was defined as left ventricular ejection fraction (LVEF) ≥40% or ≥50% respectively and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels >125 pg/ml. Patients who remained free from AF, or any atrial tachycardia of more than 30 seconds, at 6 months postoperatively, were included in this study. Patients with AF recurrences during this period were excluded. The primary outcome was the change of NT-proBNP at 6 month follow-up.

Results

From 2008 to 2017, 92 patients undergoing thoracoscopic AF ablation fulfilled the aforementioned criteria and were included. Of these patients, mean age was 61±8 years and 66 (72%) were male. Median NT-proBNP was 366 pg/ml (128–2916) and mean LVEF was 53±7%. Thirty (35%) patients had a LVEF of 40–49%. Six months after elimination of AF, NT-proBNP was <125 pg/ml (Figure 1A: median 87 (50–122) vs 459 (137 – 2916) pg/ml at baseline; p<0.001) in 26 patients (28%), whereas in the remaining patients NT-proBNP was unchanged (Figure 1B: median 298 (126–1568) vs. 318 (128–2387) pg/ml at baseline; p=0.011).

Figure 1. NT-proBNP alterations after thoracoscopic AF ablation from baseline to 6 month follow-up. A. Patients with normalization of NT-proBNP. B. Patients with unchanged high levels of NT-proBNP.

Conclusion

In 28% of patients the diagnostic criteria of HFpEF/HFmrEF are caused by AF and normalize upon elimination of AF with thoracoscopic ablation.

P2454Left atrial strain and recurrence of atrial fibrillation after thoracoscopic atrial fibrillation surgery

Background

Left atrial (LA) strain has a prognostic value for atrial fibrillation (AF) recurrence after AF ablation. The value of LA strain as a predictor of AF recurrence after thoracoscopic AF surgery in patients in sinus rhythm (SR) or AF during echocardiography is unknown.

Purpose

To assess the association between LA strain and AF recurrence after thoracoscopic surgery for AF in both patients in SR and AF during baseline echocardiography.

Methods

Patients participating in the AFACT trial (n=240) with baseline transthoracic echocardiography (TTE) suitable for LA strain analysis were included in this subanalyses. All patients underwent thoracoscopic pulmonary vein isolation (PVI) with left atrial appendage (LAA) exclusion, and were randomized to ganglion plexus (GP) or no GP ablation. LA strain and mechanical dispersion (MD) of the LA reservoir, conduit and contraction phase were determined retrospectively from TTE images of both patients in AF and SR before thoracoscopic AF surgery. AF recurrence was defined as any recorded atrial tachyarrhythmia lasting >30 sec during a one year FU period.

Results

A total of 204 patients (58.6±7.8 years, 73% male, 57% persistent AF) were included. Of the 204 patients 121 (59%) were in SR and 83 (41%) were in AF during baseline TTE. Patients in SR during TTE had higher LA strain values and lower MD compared to patients in AF. Of all patients, those with AF recurrence had lower LA strain of the reservoir phase (13.0% vs. 16.6%; p=0.003) and contraction phase (7.4% vs. 11.5%; p=0.012). MD of the contraction phase was increased in patients with AF recurrence (65.1msec vs. 19.2 msec; p=0.003). Multivariable cox regression analysis showed an association between LA strain, MD and AF recurrence (figure).

Conclusions

Left atrial strain and mechanical dispersion prior to thoracoscopic AF surgery are associated with recurrence of AF. LA strain showed to be a valuable tool to add in the decision making for thoracoscopic AF surgery regardless rhythm during baseline echocardiography.

P1017Thoracoscopic AF ablation is a successful treatment for patients with a giant left atrium

Background

Severely enlarged left atrial (LA) volume is associated with a considerable ineffective outcome of ablation for atrial fibrillation (AF). Therefore, in patients with AF and a giant atrial volume catheter ablation is not recommended. However, thoracoscopic AF ablation is being performed in patients with AF and giant LA, but with unknown efficacy.

Purpose

To determine efficacy of thoracoscopic AF ablation in patients with AF and a giant LA.

Methods

Patients underwent thoracoscopic AF ablation (paroxysmal AF) plus additional left atrial ablations (persistent AF) and were prospectively followed. Giant LA was defined as left atrial volume index (LAVI)≥50 ml/m2, outcome was also assessed for LAVI≥55 ml/m2. Follow-up was performed with ECGs and 24-hour Holters every three months. After a 3-month blanking period, all AADs were discontinued. Primary outcome was recurrence of any atrial tachycardia ≥30 sec during one year of follow-up.

Results

Between 2008–2017, 357 patients underwent thoracoscopic AF ablation. At baseline, giant LA was diagnosed in 72 (20.2%) patients (mean LAVI: 59.5±9.6 ml/m2), while 285 (79.8%) had a smaller left atrium (mean LAVI: 36.3±7.8 ml/m2), p<0.001. Giant LA patients were older (mean: 61.7±6.9 vs 59.3±9.0 years, p=0.03) and more often diagnosed with persistent AF (n=60, 83.3%) compared to control (n=164, 57.5%), p<0.001. Sex (female: n=19, 26.4% vs n=79, 27.7%, p=0.82) and history of AF (median: 4.0 [IQR: 2.0–6.0] vs 4.0 [IQR: 2.0–8.0] years, p=0.10) were equally distributed. Freedom of any atrial tachycardia did not differ significantly between both groups (n=43, 59.7% vs n=195, 68.4%, log rank p=0.91), figure. This was similar for the cut-off of LAVI≥55 ml/m2: n=24/43 (55.8%) vs n=214/314 (68.2%), p=0.15). AF recurred in 16 (22.2%) patients with giant LA compared to 55 (19.3%) patients, while atrial tachycardia recurred in 21 (29.2%) vs 56 (19.6%) patients, respectively, p=0.06.

Kaplan-Meier analysis of AF recurrence i

Conclusion

Thoracoscopic AF ablation is an effective therapy in patients with a giant LA. Thoracoscopic AF ablation may therefore be a feasible treatment for patients with a giant LA.

Body mass index and body fat distribution and new-onset atrial fibrillation: Substudy of the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk) study

BACKGROUND AND AIM

Obesity is a recognized risk factor for new-onset atrial fibrillation (AF). The association between body fat distribution, which is measured by body mass index (BMI) and waist-hip ratio (WHR), its changes, and new-onset AF is conflicting.

METHODS AND RESULTS

Participants of the European Prospective Investigation into Cancer and Nutrition in Norfolk cohort study were included, with exclusion criteria of prevalent AF, rheumatic heart disease, and cancer. AF was confirmed by the International Classification of Diseases-10 hospital discharge code I48. Adjusted sex-specific Cox proportional hazards models were used to quantify the AF risk per 1 standard deviation increase and for quintiles of adiposity indices. A total of 10,885 men and 12,857 women were followed up for a median of 19 years, yielding 451,098 person-years. New-onset AF was diagnosed in 1408 (12.9%) men and 1102 (8.6%) women. Multivariable analyses showed that BMI predicted new-onset AF in all, while WHR predicted only in men. New-onset AF risk gradually increased across the range of adiposity indices: for men in the highest BMI quintile, HR: 1.59 (CI 1.32-1.91, p for trend<0.001), whereas for women in the highest BMI quintile, HR: 1.52 (CI 1.23-1.88, p for trend<0.001). Further, for men in the highest WHR quintile, HR: 1.31 (CI 1.09-1.57, p for trend: 0.01), whereas for women in the highest WHR quintile, HR: 1.12 (CI 0.90-1.41, p for trend: 0.17). The change in BMI and WHR was similar in participants with or without new-onset AF.

CONCLUSIONS

An increased body mass, as measured by BMI, is associated with an increased risk of developing new-onset AF. More abdominal fat distribution, as measured by WHR, is associated with an increased risk of developing new-onset AF in men but not in women.

Risk of Cerebral Venous Thrombosis in Obese Women

IMPORTANCE

Obesity is a risk factor for deep vein thrombosis of the leg and pulmonary embolism. To date, however, whether obesity is associated with adult cerebral venous thrombosis (CVT) has not been assessed.

OBJECTIVE

To assess whether obesity is a risk factor for CVT.

DESIGN, SETTING, AND PARTICIPANTS

A case-control study was performed in consecutive adult patients with CVT admitted from July 1, 2006 (Amsterdam), and October 1, 2009 (Berne), through December 31, 2014, to the Academic Medical Center in Amsterdam, the Netherlands, or Inselspital University Hospital in Berne, Switzerland. The control group was composed of individuals from the control population of the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis study, which was a large Dutch case-control study performed from March 1, 1999, to September 31, 2004, and in which risk factors for deep vein thrombosis and pulmonary embolism were assessed. Data analysis was performed from January 2 to July 12, 2015.

MAIN OUTCOMES AND MEASURES

Obesity was determined by body mass index (BMI). A BMI of 30 or greater was considered to indicate obesity, and a BMI of 25 to 29.99 was considered to indicate overweight. A multiple imputation procedure was used for missing data. We adjusted for sex, age, history of cancer, ethnicity, smoking status, and oral contraceptive use. Individuals with normal weight (BMI <25) were the reference category.

RESULTS

The study included 186 cases and 6134 controls. Cases were younger (median age, 40 vs 48 years), more often female (133 [71.5%] vs 3220 [52.5%]), more often used oral contraceptives (97 [72.9%] vs 758 [23.5%] of women), and more frequently had a history of cancer (17 [9.1%] vs 235 [3.8%]) compared with controls. Obesity (BMI ≥30) was associated with an increased risk of CVT (adjusted odds ratio [OR], 2.63; 95% CI, 1.53-4.54). Stratification by sex revealed a strong association between CVT and obesity in women (adjusted OR, 3.50; 95% CI, 2.00-6.14) but not in men (adjusted OR, 1.16; 95% CI, 0.25-5.30). Further stratification revealed that, in women who used oral contraceptives, overweight and obesity were associated with an increased risk of CVT in a dose-dependent manner (BMI 25.0-29.9: adjusted OR, 11.87; 95% CI, 5.94-23.74; BMI ≥30: adjusted OR, 29.26; 95% CI, 13.47-63.60). No association was found in women who did not use oral contraceptives.

CONCLUSIONS AND RELEVANCE

Obesity is a strong risk factor for CVT in women who use oral contraceptives.