Location of epicardial adipose tissue affects the efficacy of a combined dominant frequency and complex fractionated atrial electrogram ablation of atrial fibrillation

Epicardial Adipose Tissue and Atrial Fibrillation Recurrence following Catheter Ablation: A Systematic Review and Meta-Analysis

(1)Introduction: Catheter ablation has become a cornerstone for the management of patients with atrial fibrillation (AF). Nevertheless, recurrence rates remain high. Epicardial adipose tissue (EAT) has been associated with AF pathogenesis and maintenance. However, the literature has provided equivocal results regarding the relationship between EAT and post-ablation recurrence.(2) Purpose: to investigate the relationship between total and peri-left atrium (peri-LA) EAT with post-ablation AF recurrence. (3) Methods: major electronic databases were searched for articles assessing the relationship between EAT, quantified using computed tomography, and the recurrence of AF following catheter ablation procedures. (4) Results: Twelve studies (2179 patients) assessed total EAT and another twelve (2879 patients) peri-LA EAT. Almost 60% of the included patients had paroxysmal AF and recurrence was documented in 34%. Those who maintained sinus rhythm had a significantly lower volume of peri-LA EAT (SMD: -0.37, 95%; CI: -0.58-0.16, I2: 68%). On the contrary, no significant difference was documented for total EAT (SMD: -0.32, 95%; CI: -0.65-0.01; I2: 92%). No differences were revealed between radiofrequency and cryoenergy pulmonary venous isolation. No publication bias was identified. (5) Conclusions: Only peri-LA EAT seems to be predictive of post-ablation AF recurrence. These findings may reflect different pathophysiological roles of EAT depending on its location. Whether peri-LA EAT can be used as a predictor and target to prevent recurrence is a matter of further research.

The Predictive Value of Epicardial Fat Tissue Volume in the Occurrence and Development of Atrial Fibrillation: A Systematic Review and Meta-Analysis

Background

Atrial fibrillation (AF) is one of the most common arrhythmias in clinical practice. Although fat is currently considered to be a risk factor for AF and a pathogenic link between epicardial fat tissue (EFT) and AF has been speculated, there are currently few clinical studies and literature data domestically or abroad.

Objective

This study conducted a meta-analysis of observational case series studies to verify the relationship between atrial fibrillation and EFT and to strengthen the predictive value of EFT in the occurrence, development, and postablative recurrence of AF.

Methods

We conducted a systematic search of the literature in electronic databases until December 2021 and supplemented this through manual searches of individual studies, reviewed articles, and reference lists in conference proceedings. This study conducted a meta-analysis to compare the differences between different populations, such as healthy participants and AF patients, healthy subjects and AF subtype cases, and paroxysmal and persistent AF with AF recurrence and without AF recurrence after ablation.

Results

Following the retrieval of 828 articles, only 22 articles were selected as research results. Accordingly, the meta-analysis results show that the volume of EFT in AF is greater than that in healthy subjects (MD = 39.34 ml, 95% CI = 27.11, 51.58); persistent AF is greater than paroxysmal AF (MD = 14.37 ml, 95% CI = 7.46, 21.27); and recurrence after ablation is greater than without recurrence (MD = 14.37 ml, 95% CI = 7.46, 21.27).

Conclusion

The results of this study further confirm the connection between EFT and AF and that EFT has a certain predictive value for the occurrence and development of AF.

Atrial Cardiomyopathy: Pathophysiology and Clinical Consequences

Around the world there are 33.5 million patients suffering from atrial fibrillation (AF) with an annual increase of 5 million cases. Most AF patients have an established form of an atrial cardiomyopathy. The concept of atrial cardiomyopathy was introduced in 2016. Thus, therapy of underlying diseases and atrial tissue changes appear as a cornerstone of AF therapy. Furthermore, therapy or prevention of atrial endocardial changes has the potential to reduce atrial thrombogenesis and thereby cerebral stroke. The present manuscript will summarize the underlying pathophysiology and remodeling processes observed in the development of an atrial cardiomyopathy, thrombogenesis, and atrial fibrillation. In particular, the impact of oxidative stress, inflammation, diabetes, and obesity will be addressed.

Posterior left atrial epicardial adipose tissue: scope of the problem and impact of new technology

PURPOSE OF REVIEW

Patients with persistent forms of atrial fibrillation are seeking treatments based on the promise of better restoration of sinus rhythm with newer therapies. Successful catheter ablation and maintenance of atrial fibrillation in this subgroup is negatively impacted by the presence of epicardial adipose tissue (EAT) associated with the posterior left atrium.

RECENT FINDINGS

EAT is now understood to be hormonally active and promotes adverse atrial remodelling, including fibrosis and myopathy. Despite being dominantly adipose tissue, it is known to be electrically active, comprising ganglia, neural tissue and ectopic atrial myocardium that may contribute to endo-epicardial dissociation and persistent electrical activity and atrial fibrillation despite good endocardial electrical silencing. Hybrid procedures that include direct epicardial ablation of the posterior wall, including the EAT, are associated with superior outcomes in nonparoxysmal atrial fibrillation.

SUMMARY

Therapies for persistent atrial fibrillation that also ablate the EAT as part of a well tolerated transmural posterior wall ablation may improve outcomes in this challenging subset of patients.

Inotropic and lusitropic, but not arrhythmogenic, effects of adipocytokine resistin on human atrial myocardium

The adipocytokine resistin is released from epicardial adipose tissue (EAT). Plasma resistin and EAT deposition are independently associated with atrial fibrillation. The EAT secretome enhances arrhythmia susceptibility and inotropy of human myocardium. Therefore, we aimed to determine the effect of resistin on the function of human myocardium and how resistin contributes to the proarrhythmic effect of EAT. EAT biopsies were obtained from 25 cardiac surgery patients. Resistin levels were measured by ELISA in 24-h EAT culture media (n = 8). The secretome resistin concentrations increased over the culture period to a maximal level of 5.9 ± 1.2 ng/mL. Coculture with β-adrenergic agonists isoproterenol (n = 4) and BRL37344 (n = 13) had no effect on EAT resistin release. Addition of resistin (7, 12, 20 ng/mL) did not significantly increase the spontaneous contraction propensity of human atrial trabeculae (n = 10) when given alone or in combination with isoproterenol. Resistin dose-dependently increased trabecula-developed force (maximal 2.9-fold increase, P < 0.0001), as well as the maximal rates of contraction (2.6-fold increase, P = 0.002) and relaxation (1.8-fold increase, P = 0.007). Additionally, the postrest potentiation capacity of human trabeculae was reduced at all resistin doses, suggesting that the inotropic effect induced by resistin might be due to altered sarcoplasmic reticulum Ca²⁺ handling. EAT resistin release is not modulated by common arrhythmia triggers. Furthermore, exogenous resistin does not promote arrhythmic behavior in human atrial trabeculae. Resistin does, however, induce an acute dose-dependent positive inotropic and lusitropic effect.

Epicardial adipose tissue affects the efficacy of left atrial posterior wall isolation for persistent atrial fibrillation

BACKGROUND

Epicardial adipose tissue (EAT) contributes to atrial fibrillation (AF). However, its impact on the efficacy of left atrial posterior wall isolation (LAPWI) is unclear.

METHODS

Forty-four nonparoxysmal AF patients underwent LAPWI after pulmonary vein isolation. EAT overlap on LAPWI was assessed by fusing computed tomography images with electro-anatomical mapping.

RESULTS

During the 21 ± 7 months of follow-up, AF recurred in 10 patients (23%). The total and left atrial EAT volumes were 113 ± 36 and 33 ± 12 cm3, respectively. No differences were found between the AF-free and AF-recurrent groups regarding EAT volume. The EAT overlaps on LAPWI lines and LAPWI area were 1.2 ± 1.0 and 0.5 ± 0.9 cm2 respectively. Although no difference was found between groups regarding the EAT overlap on LAPWI area, the AF-free group had a significantly larger EAT overlap on LAPWI lines (1.4 ± 1.0 vs 0.6 ± 0.6 cm2, P = .014). Multivariate analysis identified EAT overlap on LAPWI lines as an independent predictor of AF recurrence (hazard ratio: 0.399, 95% confidence interval: 0.178-0.891, P = .025). Kaplan-Meier analysis revealed that, during follow-up, 92% of the large EAT overlap group (≥1.0 cm2) and 58% of the small EAT overlap group (<1.0 cm2) remained AF-free (P = .008).

CONCLUSIONS

EAT overlap on LAPWI lines is related to a high AF freedom rate. Direct radiofrequency application to EAT overlap may be necessary to suppress AF.

Ripple map guided catheter ablation targeting abnormal atrial potentials during sinus rhythm for non-paroxysmal atrial fibrillation

BACKGROUND

Abnormal atrial potential (AAP) during sinus rhythm may be a critical ablation target for atrial fibrillation. However, the assessment of local electrograms throughout the left atrium is difficult. Thus, we sought to investigate the effectiveness of Ripple map guided AAP ablation.

METHODS AND RESULTS

AAP areas were determined by Ripple mapping on the CARTO system in 35 patients (Ripple group) by marking the area where small deflections persisted after the first deflection wavefront had passed. Following pulmonary vein isolation, AAP areas were ablated. If AAP areas were located on the left atrial posterior wall, the posterior wall was isolated. The outcome of this approach was compared with that of 66 patients who underwent an empirical linear ablation approach (control group). There were no differences in patient characteristics between the groups. The total radiofrequency application time and procedure time were shorter in the Ripple group than in the control group (radiofrequency application time, 48 ± 14 minutes vs 61 ± 13 minutes, P < .001; procedure time, 205 ± 30 minutes vs 221 ± 27 minutes, P = .013). Gastroparesis occurred in one patient in each group (P = .645), but in both cases this was relieved with conservative therapy. Kaplan-Meier analysis revealed that rate of freedom from atrial arrhythmia was higher in the Ripple group than in the control group (91% vs 74% during the 12 months' follow up; P = .040).

CONCLUSION

Ripple map guided AAP ablation effectively suppressed atrial arrhythmia in patients with non-paroxysmal AF.

Correlation between coronary atherosclerosis calcification and epicardial adipose tissue volume in patients with nephropathy

Correlation between coronary atherosclerosis calcification and epicardial adipose tissue (EAT) volume in patients with nephropathy was investigated. A total of 529 patients with high risk of coronary atherosclerotic nephropathy were selected from August 2013 to September 2016 in Xianyang Central Hospital to serve as research subjects, and their clinical data were retrospectively analyzed. All patients underwent coronary artery and EAT examination using dual-source CT. Correlation between EAT and severity of coronary atherosclerosis, calcification, lesions, and BMI were analyzed. Volume of EAT in patients with atherosclerosis was significantly higher than that in patients without atherosclerosis (p<0.05). EAT volume was positively correlated with BMI (r=0.61, p<0.05), calcification scores (r=0.72, p<0.05) and the number of coronary artery lesions (r=0.64, p<0.05) in patients with nephropathy. Coronary atherosclerosis calcification score, number of lesions and BMI are positively correlated with the EAT volume in patients with nephropathy. Detection of EAT volume may serve as a predictor of the occurrence and develop-ment of coronary atherosclerosis in the future.

Underrecognized entity of the transient rise in the atrial capture threshold early after dual-chamber pacemaker implantation

BACKGROUND

Steroid-eluting pacemaker leads suppress acute rises in pacing threshold by preventing inflammatory processes. However, we occasionally encounter not persistent but transient rise in the atrial capture threshold (TRACT) early after pacemaker implantation. We believe that this phenomenon is underrecognized in clinical practice and may potentially lead to unnecessary reintervention. We aimed to clarify the prevalence, predictors, and possible mechanisms of TRACT.

METHODS AND RESULTS

We reviewed clinical records from 239 consecutive patients who underwent dual-chamber pacemaker implantation for sick sinus syndrome (SSS) (N = 102) or atrioventricular block (AVB) (N = 137). Atrial capture threshold was measured at implantation and 7 days, 2 months, and 8 months postimplantation. TRACT was defined as a rise in the threshold at day 7 to ≥twice that at implantation, with an absolute value ≥1.0 V/0.4 ms, and full recovery by 8 months into follow-up. TRACT was observed in 15 patients (6%), of whom13 (87%) suffered from SSS but not AVB. Patients with TRACT had greater body mass index (BMI) (25 ± 5 kg/m² vs 23 ± 4 kg/m² , P = 0.01), larger left atrium (42 ± 5 mm vs 38 ± 7 mm, P = 0.03), and were more likely to suffer from paroxysmal atrial fibrillation (60% vs 31%, P = 0.02) than those without TRACT. In multivariable logistic regression analysis, BMI and SSS were the independent predictors of TRACT (odds ratio [OR], 1.172; 95% confidence interval [CI], 1.019-1.349; P = 0.03 and OR, 11.53; 95% CI, 2.010-66.21; P = 0.006, respectively).

CONCLUSIONS

The distinct phenomenon of TRACT was not rare in clinical practice early after dual-chamber pacemaker implantation, and its occurrence was strongly associated with SSS.

Vagal response in cryoballoon ablation of atrial fibrillation and autonomic nervous system: Utility of epicardial adipose tissue location

Background

Mechanism and effects of vagal response (VR) during cryoballoon ablation procedure on the cardiac autonomic nervous system (ANS) are unclear. The present study aimed to evaluate the relationship between VR during cryoballoon catheter ablation for atrial fibrillation and ANS modulation by evaluating epicardial adipose tissue (EAT) locations and heart rate variability (HRV) analysis.

Methods

Forty-one patients with paroxysmal atrial fibrillation (11 with VR during the procedure and 30 without VR) who underwent second-generation cryoballoon ablation were included. EAT locations and changes in HRV parameters were compared between the VR and non-VR groups, using Holter monitoring before ablation, immediately after ablation and one month after ablation.

Results

The total EAT volume surrounding the left atrium (LA) in the VR and non-VR groups was 29.0±18.4 cm³ vs 27.7±19.7 cm³, respectively (p=0.847). The VR group exhibited greater EAT volume overlaying the LA-left superior pulmonary vein (PV) junction (6.1±3.6 cm³ vs 3.6±3.3 cm³, p=0.039) than the non-VR group. HRV parameters similarly changed following ablation in both the groups. EAT volume overlaying LA-right superior PV junction was significantly correlated with the relative changes in root-mean-square successive differences (r=−0.317, p=0.043) and high frequency (r=−0.331, p=0.034), immediately after the ablation.

Conclusions

Changes in HRV parameters following ablation were similarly observed in both the groups. EAT volume on the LA-PV junction is helpful for interpretation of VR occurrence and ANS modulation.

Evaluation of the characteristics of rotational activation at high-dominant frequency and complex fractionated atrial electrogram sites during atrial fibrillation

Background

High-dominant frequency (DF) and continuous complex fractionated atrial electrogram (CFAE) sites as surrogates for localized sources maintaining atrial fibrillation (AF) are potential AF ablation targets. This study aimed to evaluate the characteristics of a rotational activation at high-DF and continuous CFAE sites in AF patients.

Methods

Thirty-two consecutive AF patients (5 paroxysmal and 27 non-paroxysmal) underwent ablation using the NavX system. When AF continued after circumferential pulmonary vein isolation (PVI), high-DF sites of ≥8 Hz and continuous CFAE sites (fractionated intervals ≤50 ms) in the left (LA) and right (RA) atria were recorded using a high-density 20-pole circular mapping catheter for 5 s and ablated.

Results

The atrial electrogram characteristics during AF were assessed. A total of 2383 AF beats from 89 high-DF and 19 continuous CFAE sites were investigated. A rotational activation of high-DF and continuous CFAE sites was also observed at 4% and 3% of LA, and 4% and 4% of RA sites, respectively. However, rotational activation was identified in 29 (91%) of 32 patients (mean 3.0±2.6 beats per patient, 80% in the LA). Procedural endpoints were achieved in 26 (81%) of 32 patients: AF termination (n=2) and AF cycle length slowing of >10% (n=26).

Conclusions

Rotational activation could be identified in high-DF and continuous CFAE sites during AF, but the documentation was limited. Therefore, only limited effects of rotational activation ablation at high-DF and/or continuous CFAE sites following PVI could be concluded.

Associations of Epicardial, Abdominal, and Overall Adiposity With Atrial Fibrillation

Background—

Although adiposity is increasingly recognized as a risk factor for atrial fibrillation (AF), the importance of epicardial fat compared with other adipose tissue depots remains uncertain. We sought to characterize and compare the associations of AF with epicardial fat and measures of abdominal and overall adiposity.

Methods and Results—

We conducted a meta-analysis of 63 observational studies including 352 275 individuals, comparing AF risk for 1-SD increases in epicardial fat, waist circumference, waist/hip ratio, and body mass index. A 1-SD higher epicardial fat volume was associated with a 2.6-fold higher odds of AF (odds ratio, 2.61; 95% confidence interval [CI], 1.89–3.60), 2.1-fold higher odds of paroxysmal AF (odds ratio, 2.14; 95% CI, 1.45–3.16) and, 5.4-fold higher odds of persistent AF (odds ratio, 5.43; 95% CI, 3.24–9.12) compared with sinus rhythm. Likewise, a 1-SD higher epicardial fat volume was associated with 2.2-fold higher odds of persistent compared with paroxysmal AF (odds ratio, 2.19; 95% CI, 1.66–2.88). Similar associations existed for postablation, postoperative, and postcardioversion AF. In contrast, associations of abdominal and overall adiposity with AF were less extreme, with relative risks per 1-SD higher values of 1.32 (95% CI, 1.25–1.41) for waist circumference, 1.11 (95% CI, 1.08–1.14) for waist/hip ratio, and 1.22 (95% CI, 1.17–1.27) for body mass index.

Conclusions—

Strong and graded associations were observed between increasing epicardial fat and AF. Moreover, the strength of associations of AF with epicardial fat is greater than for measures of abdominal or overall adiposity. Further studies are needed to assess the mechanisms and clinical relevance of epicardial fat.

Efficacy of atrial substrate modification based on dominant frequency of paroxysmal atrial fibrillation

Background

The endpoint of ablation procedures is suggested to be non-inducibility of paroxysmal atrial fibrillation (PAF). However, the prognosis of induced AF/atrial tachycardia (AT) after pulmonary vein isolation (PVI) in PAF patients remains unclear.

Methods

A total of 122 PAF patients were divided into the following 3 groups: Group 1, 79 without AF/AT induced after PVI; Group 2, 21 with AF/AT induced or sustained after PVI, and followed by a high-dominant frequency (DF) and continuous complex fractionated atrial electrogram (CFAE) site ablation and, if necessary, linear ablation; and Group 3, 22 with external cardioversion of AF/AT induced or sustained after PVI. High-DF (DF≥8 Hz) and continuous CFAE (fractionated intervals≤50 ms) sites were targeted. The ablation endpoint was non-inducibility of PAF.

Results

In Group 2, AF terminated in 2 patients with a high-DF and continuous CFAE site ablation. In 4 patients, AF induced after cardioversion did not terminate with left atrium linear ablation, and required additional cardioversion. Common atrial flutter in 2 patients terminated with cavotricuspid isthmus ablation. An AT terminated with a roofline ablation. Finally, no AF/AT could be induced in any of the patients in Group 2 after all the procedures. The cumulative freedom from AF/AT recurrence without antiarrhythmic drugs in Groups 1 and 2 was significantly greater than that in Group 3 after 1 procedure during 12 months of follow-up (90% and 91% vs. 64%, Log-rank test P=0.001 and P=0.033, respectively).

Conclusions

Atrial substrate ablation may improve the clinical outcome after ablation in patients after PVI with residual arrhythmia inducibility.

Electrogram Fractionation-Guided Ablation in the Left Atrium Decreases the Frequency of Activation in the Pulmonary Veins and Leads to Atrial Fibrillation Termination: Pulmonary Vein Modulation Rather Than Isolation

OBJECTIVES

This study sought to evaluate the impact of a complex fractionated atrial electrogram (CFAE)-guided ablation strategy on atrial fibrillation (AF) dynamics in patients with persistent AF.

BACKGROUND

It is still unclear whether complete pulmonary vein isolation (PVI) is required or if the ablation of well-delineated pulmonary vein (PV) subregions could achieve similar outcomes in persistent AF.

METHODS

CFAE-guided ablations were performed in 76 patients (65.2 ± 10 years of age) with persistent AF. In 47 patients, we measured mean PVs and left atrial appendage (LAA) cycle length (CL) values (PV-CL and LAA-CL), before ablation and before AF termination. We defined "active" PVs as PV-CL ≤ LAA-CL, "rapid fires" as PV-CL ≤80% of LAA-CL, and "PV-LAA CL gradient" as a significant CL difference between the 2 regions.

RESULTS

AF termination (sinus rhythm [SR] or atrial tachycardia [AT] conversion) occurred in 92% and SR conversion in 75%. The radiofrequency time for AF termination and total radiofrequency time were 26 ± 25 min and 61.1 ± 21.6 min, respectively. Thirty of 47 patients had active PV (with 19 PV "rapid fires"). Ablation significantly increased median CL, both at PVs and LAA from 188 ms (interquartile range [IQR]: 161 to 210 ms) to 227.5 ms (IQR: 200 to 256 ms) (p < 0.0001) and from 197 ms (IQR: 168 to 220 ms) to 224 ms (IQR: 193 to 250 ms) (p < 0001), respectively. After ablation, PV-LAA CL gradients were withdrawn and all PV "rapid fires" were extinguished (without PVI). After 17.2 ± 10 months of follow-up and 1.61 ± 0.75 procedures, 86.3% and 73% of the patients were free from AF and from any arrhythmia (AF/AT), respectively.

CONCLUSIONS

CFAE-guided ablation leads to a large decrease in PV frequency of activation, preceding AF termination. A PV modulation approach, rather than complete PVI, may be preferable for persistent AF.

Atrial fibrillation and rapid acute pacing regulate adipocyte/adipositas-related gene expression in the atria

PURPOSE

Atrial fibrillation (AF) has been associated with increased volumes of epicardial fat and atrial adipocyte accumulation. Underlying mechanisms are not well understood. This study aims to identify rapid atrial pacing (RAP)/AF-dependent changes in atrial adipocyte/adipositas-related gene expression (AARE).

METHODS

Right atrial (RA) and adjacent epicardial adipose tissue (EAT) samples were obtained from 26 patients; 13 with AF, 13 in sinus rhythm (SR). Left atrial (LA) samples were obtained from 9 pigs (5 RAP, 4 sham-operated controls). AARE was analyzed using microarrays and RT-qPCR. The impact of diabetes/obesity on gene expression was additionally determined in RA samples (RAP ex vivo and controls) from 3 vs. 6 months old ZDF rats.

RESULTS

RAP in vivo of pigs resulted in substantial changes of AARE, with 66 genes being up- and 53 down-regulated on the mRNA level. Differential expression during adipocyte differentiation was confirmed using 3T3-L1 cells. In patients with AF (compared to SR), a comparable change in RA mRNA levels concerned a fraction of genes only (RETN, IGF1, HK2, PYGM, LOX, and NR4A3). RA and EAT were affected by AF to a different extent. In patients, concomitant disease contributes to AARE changes.

CONCLUSIONS

RAP, and to lesser extent AF, provoke significant changes in atrial AARE. In chronic AF, activation of this gene panel is very likely mediated by AF itself, AF risk factors and concomitant diseases. This may facilitate the development of an AF substrate by increasing atrial ectopic fat and fat infiltration of the atrial myocardium.