Clinical usefulness of digital twin guided virtual amiodarone test in patients with atrial fibrillation ablation

It would be clinically valuable if the efficacy of antiarrhythmic drugs could be simulated in advance. We developed a digital twin to predict amiodarone efficacy in high-risk atrial fibrillation (AF) patients post-ablation. Virtual left atrium models were created from computed tomography and electroanatomical maps to simulate AF and evaluate its response to varying amiodarone concentrations. As the amiodarone concentration increased in the virtual setting, action potential duration lengthened, peak upstroke velocities decreased, and virtual AF termination became more frequent. Patients were classified into effective (those with virtually terminated AF at therapeutic doses) and ineffective groups. The one-year clinical outcomes after AF ablation showed significantly better results in the effective group compared to the ineffective group, with AF recurrence rates of 20.8% vs. 45.1% (log-rank p = 0.031, adjusted hazard ratio, 0.37 [0.14-0.98]; p = 0.046). This study highlights the potential of a digital twin-guided approach in predicting amiodarone's effectiveness and improving personalized AF management. Clinical Trial Registration Name: The Evaluation for Prognostic Factors After Catheter Ablation of Atrial Fibrillation: Cohort Study, Registration number: NCT02138695. The date of registration: 2014-05. URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02138695.

The role of left atrium posterior wall isolation in patients undergoing catheter ablation for atrial fibrillation

The posterior left atrium (LAPW) is an important substrate for initiation and maintenance of atrial fibrillation (AF). While it has been proposed as a potential target for preventing recurrence of atrial tachyarrhythmias, it remains unclear whether electrical silence of LAPW offers additional benefits over pulmonary vein isolation (PVI) alone. We conducted a systematic review of PubMed, Medline, Embase, and Cochrane databases and identified 21 eligible studies, encompassing 1514 patients assigned to PVI + posterior wall isolation (PWI) group and 1629 patients assigned to PVI group. Over a median follow-up of 12 months, adjunctive PWI significantly improved the atrial tachyarrhythmia-free survival by 14 % in comparison to PVI alone [relative risk (RR): 1.14, 95 % confidence interval (CI): 1.04 to 1.25, p = 0.004]. This improvement was mainly attributed to a pronounced benefit for patients with persistent AF. In addition, patients undergoing PVI + PWI had a longer procedure time [weighted mean difference (WMD): 23.85, 95 % CI: 12.68 to 35.01, p < 0.001], ablation time (WMD: 9.27, 95 % CI: 5.19 to 13.54, p < 0.001), and a nearly negligible increase in fluoroscopic exposure (WMD: 2.69, 95 % CI: -0.23 to 5.62, p = 0.071). There was no increased risk of procedure-related complications between these approaches (RR: 1.06, 95 % CI: 0.71 to 1.57, p = 0.787). Compared with PVI alone, PWI adjunctive to PVI exhibited a higher procedure success of sinus rhythm maintenance in persistent AF during an index catheter ablation. Meanwhile, elongated procedure time and ablation time did not compromise the safety of extensive ablation strategy with additional PWI.

Adjunctive left atrial posterior wall isolation for atrial fibrillation: An updated systematic review and meta-analysis

OBJECTIVE

Posterior left atrial wall isolation (PWI) plus traditional pulmonary vein isolation (PVI) has been proposed as a promising intervention to decrease atrial fibrillation (AF) recurrence. We aim to investigate the efficacy and safety of adding PWI to the traditional PVI in patients with AF.

METHODS

A systematic review and meta-analysis was conducted using synthesizing randomized controlled trials (RCTs) retrieved by systematically searching PubMed, Web of Science, SCOPUS, EMBASE, and Cochrane through June 14, 2023. We used Stata version 17 to pool dichotomous data using risk ratio (RR) and continuous data using mean difference (MD), with a 95% confidence interval (CI) (PROSPERO ID: CRD42023446227).

RESULTS

We included 11 RCTs with a total number of 1534 patients. Combined ablation with PWI + PVI was not associated with any significant difference over PVI only regarding the recurrence of clinical AF (RR: 0.86 with 95% CI [0.70-1.06]), all atrial arrhythmia (RR: 0.93 with 95% CI [0.82-1.07]), nonatrial fibrillation arrhythmia (RR: 1.22 with 95% CI [0.97-1.53]), early AF (RR: 0.89 with 95% CI [0.62-1.27]), and antiarrhythmic drugs at discharge (RR: 0.83 with 95% CI [0.67-1.04]). However, it was associated with increased total ablation duration (minutes) (MD: 12.58 with 95% CI [6.80-18.37]) and total procedure duration (minutes) (MD: 16.77 with 95% CI [9.63-23.91]), without any significant difference regarding adverse events (RR: 1.05 with 95% CI [0.63-1.74]).

CONCLUSION

While the pooled data from PWI + PVI using point-by-point radiofrequency did not suggest a benefit in the recurrence of various atrial arrhythmias compared to PVI alone, PWI+PVI using direct posterior wall ablation, especially with cryoballoon, demonstrated a significant reduction in recurrence of AF/atrial arrhythmias. Also, PWI + PVI significantly increased the ablation and total procedure durations.

Impact of Posterior Wall Isolation During AF Ablation on the Incidence of Left Atrial Flutter

BACKGROUND

Linear and complex electrogram ablation (LCEA) beyond pulmonary vein isolation (PVI) is associated with an increase in left atrial macro-re-entrant tachycardias (LAMTs). Posterior wall isolation (PWI) is increasingly performed to improve AF ablation outcomes. However, the impact of PWI on the incidence of LAMT is unknown.

OBJECTIVES

The purpose of this study was to establish the incidence of LAMT following PVI alone vs PVI + PWI vs PVI + PWI + LCEA.

METHODS

Consecutive patients undergoing catheter ablation for AF or LAMT post-AF ablation between 2008 and 2022 from 4 electrophysiology centers were reviewed with a minimum follow-up of 12 months.

RESULTS

In total, 5,619 (4,419 index, 1,100 redo) AF ablation procedures were performed in 4,783 patients (mean age 60.9 ± 10.6 years, 70.7% men). Over a mean follow-up of 6.4 ± 3.8 years, 246 procedures for LAMT were performed in 214 patients at a mean of 2.6 ± 0.6 years post-AF ablation. Perimitral (52.8% of patients), roof-dependent (27.1%), PV gap-related (17.3%), and anterior circuits (8.9%) were most common, with 16.4% demonstrating multiple circuits. The incidence of LAMT was significantly higher following PVI + PWI (6.2%) vs PVI alone (3.0%; P < 0.0001) and following PVI + PWI + LCEA vs PVI + PWI (12.5%; P = 0.019). Conduction gaps in previous ablation lines were responsible for LAMT in 28.4% post-PVI alone, 35.3% post-PVI + PWI (P = 0.386), and 81.8% post-PVI + PWI + LCEA (P < 0.005).

CONCLUSIONS

The incidence of LAMT following PVI + PWI is higher than with PVI alone but significantly lower than with more extensive atrial substrate modification. Given a low frequency of LAMT following PWI, empiric mitral isthmus ablation is not justified and may be proarrhythmic.

Bachmann's Bundle Modification in Addition to Circumferential Pulmonary Vein Isolation for Atrial Fibrillation: A Novel Ablation Strategy

Background

Bachmann's bundle (BB) is the main pathway of interatrial connection that could be involved in the development of atrial fibrillation (AF). Based on this hypothesis, we raised a novel ablation strategy, BB modification in addition to circumferential pulmonary vein isolation (CPVI-BB) in patients with AF.

Methods

A retrospective cohort of patients with AF who underwent CPVI-BB or CPVI alone from March 2018 to July 2021 was enrolled in our study. Propensity score matching was performed in patients with paroxysmal AF and persistent AF, respectively, to reduce the risk of selection bias between the treatment strategies (CPVI-BB or CPVI alone). The primary endpoint was overall freedom from atrial arrhythmia recurrence through 12 months of follow-up.

Results

Our propensity score-matched cohort included 82 patients with paroxysmal AF (CPVI group: n = 41; CPVI-BB group: n = 41) and 168 patients with persistent AF (CPVI group: n = 84; CPVI-BB group: n = 84). Among patients with persistent AF, one-year freedom from atrial arrhythmia recurrence rate was 83.3% in the CPVI-BB group and 70.2% in the CPVI group (log-rank P = 0.047). Among patients with paroxysmal AF, no significant difference was found in the primary endpoint between two groups (85.4% in the CPVI-BB group vs. 80.5% in the CPVI group; log-rank P = 0.581). In addition, procedure-related complications and recurrence of atrial tachycardia or atrial flutter were similar between the two treatment groups, regardless of the type of AF.

Conclusions

BB modification in addition to CPVI is an effective approach in increasing the maintenance of sinus rhythm in patients with persistent AF, while it does not improve the clinical outcomes of radiofrequency catheter ablation in patients with paroxysmal AF.

Radiofrequency catheter ablation of atrial fibrillation: A review of techniques

Ablation of atrial fibrillation is a key area of current research. A multitude of techniques have been tested, some of which are poorly evidenced and not recommended in routine clinical practice whilst others are more promising. Additionally, a plethora of issues exist when researching ablation techniques, from control arm ablation strategy to the relevance of outcome measures. In this review article, we discuss these issues in the context of the current evidence base.

Pulmonary Vein Isolation With and Without Posterior Wall Isolation in Paroxysmal Atrial Fibrillation: IMPPROVE-PAF Trial

BACKGROUND

Prior studies have demonstrated clinical benefits associated with cryoballoon pulmonary vein isolation (PVI) and concomitant posterior wall isolation (PWI) in patients with persistent atrial fibrillation (AF). However, the role for this approach in patients with paroxysmal atrial fibrillation (PAF) remains unclear.

OBJECTIVES

This study investigated the acute and long-term outcomes of PVI vs PVI+PWI using cryoballoon in patients with symptomatic PAF.

METHODS

This retrospective study (NCT05296824) examined the outcomes of cryoballoon PVI (n = 1,342) vs cryoballoon PVI+PWI (n = 442) in patients with symptomatic PAF during long-term follow-up. Using the nearest-neighbor method, a 1:1 matched sample of patients receiving PVI alone and PVI+PWI was created.

RESULTS

The matched cohort consisted of 320 patients (PVI: n = 160; PVI+PWI: n = 160). PVI+PWI was associated with longer cryoablation (23 ± 10 minutes vs 42 ± 11 minutes; P < 0.001) and procedure times (103 ± 24 minutes vs 127 ± 14 minutes; P < 0.001). In 39 (24.4%) of 160 patients, adjunct radiofrequency ablation was required for PVI+PWI. Adverse event rates were similar (PVI 3.8% vs PVI+PWI 1.9%; P = 0.31). Though there were no differences at 12 months, freedom from all atrial arrhythmias (67.5% vs 45.0%; P < 0.001) and AF (75.6% vs 55.0%; P < 0.001) were significantly greater with PVI+PWI vs PVI alone at 39 ± 9 months of follow-up. PVI+PWI was also associated with reduced long-term need for cardioversion (16.9% vs 27.5%; P = 0.02) and repeat catheter ablation (11.9% vs 26.3%; P = 0.001), and emerged as the only significant predictor of freedom from recurrent AF (HR: 2.79; 95% CI: 1.64-4.74; P < 0.001).

CONCLUSIONS

Compared with cryoballoon PVI, cryoballoon PVI+PWI appears to be associated with greater freedom from recurrent atrial arrhythmias and AF in patients with PAF during long-term follow-up >3 years.

Risk and benefit of extrapulmonary vein ablation in atrial fibrillation

PURPOSE OF REVIEW

This review aims to summarize the recent development, benefit, and safety of extrapulmonary vein ablation for atrial fibrillation.

RECENT FINDING

Studies have shown that extrapulmonary vein ablation can help maintain normal sinus rhythm for patients with persistent atrial fibrillation. As prior strategies targeting anatomical lines and triggers are well utilized, novel techniques for substrate mapping have been rapidly developing. These strategies are well tolerated and could be chosen based on patients' conditions and physicians' experience.

SUMMARY

Extrapulmonary vein ablation could be safely and effectively performed for patients with atrial fibrillation. It provides further consolidation of normal sinus rhythm.

Posterior wall substrate modification using optimized and contiguous lesions in patients with atrial fibrillation

BACKGROUND

Radiofrequency (RF) linear ablation at the left atrial (LA) roof and bottom to isolate the LA posterior wall using contiguous and optimized RF lesions was evaluated. Achieving isolation of the LA posterior wall is challenging as two continuous linear lesion sets are necessary.

METHODS

Forty consecutive patients with symptomatic atrial fibrillation (AF) and arrhythmia substrates affecting the LA posterior wall underwent posterior wall isolation by linear lesions across the roof and bottom. The cohort was divided into two groups: group 1 (20 patients) linear ablation guided by contact force (CF) only; group 2 (20 patients) guided by ablation index (AI) and interlesion distance.

RESULTS

Bidirectional block across the LA roof and bottom was achieved in 40/40 patients. Additional endocardial RF applications in 5 patients from group 1 vs. 3 patients from group 2 resulted in posterior wall isolation in all patients. Procedure duration was almost equal in both groups. CF and AI were significantly higher in group 2 for the roof line, whereas no statistical difference was found for the bottom line. AI-guided LA posterior wall isolation led to a significantly lower maximum temperature increase. The mean AI value as well as the mean value for catheter-to-tissue CF for the roof line were significantly higher when AI-guided ablation was performed. Standard deviation in group 2 showed a remarkably lower dispersion.

CONCLUSIONS

Ablation index guided posterior wall isolation for substrate modification is safe and effective. AI guided application of the posterior box lesion allows improved lesion formation.

The efficacy of posterior wall isolation in atrial fibrillation ablation: A systematic review and meta-analysis of randomized controlled trials

Background

Posterior wall isolation (PWI) is an emerging approach in atrial fibrillation (AF) ablation, yet its efficacy remains controversial. This is the first meta-analysis of randomized controlled trials (RCT) to evaluate the efficacy of PWI in AF ablation.

Objective

To assess the efficacy of PWI in reducing atrial arrhythmia recurrence following initial AF ablation at long-term follow-ups when compared to conventional methods.

Methods

We conducted a literature search from inception through September 2021 in EMBASE and MEDLINE databases. We included RCTs that compared outcomes in PWI and conventional approaches of AF ablation. Data from each study were combined using the random-effects, generic inverse variance method of DerSimonian and Laird to calculate odds ratio (OR), and 95% confidence interval (CI).

Results

Eight RCT from 2009 to 2020, including 1024 AF patients, were included. PWI did not decrease overall atrial arrhythmias recurrence (RR 0.96, 95% CI:0.88-1.05, I 2 = 31.6%, p-value 0.393). However, the pooled analysis showed a significant decrease in AF recurrence in PWI compared to controlled approaches (RR 0.88, 95% CI:0.81-0.96, I 2 = 48.2%, p-value .004). In the subgroup analysis, PWI significantly decreased AF recurrence in the studies that included only persistent AF (RR = 0.89, 95% CI:0.80-0.98, I 2 = 65.2%, p-value .014). PWI significantly decreased AF recurrence when compared to PVI with roof line (RR 0.84, 95% CI 0.74-0.95, I 2 0.00%, p-value .008).

Conclusion

Our study suggests that adding PWI significantly decreased AF recurrence in patients with persistent AF compared to controlled approaches. It highlights the importance of considering PWI during the initial procedure in this patient population.

Comparing efficacy and safety in catheter ablation strategies for atrial fibrillation: a network meta-analysis

BACKGROUND

There is no consensus on the most efficient catheter ablation (CA) strategy for patients with atrial fibrillation (AF). The objective of this study was to compare the efficacy and safety of different CA strategies for AF ablation through network meta-analysis (NMA).

METHODS

A systematic search of PubMed, Web of Science, and CENTRAL was performed up to October 5th, 2020. Randomized controlled trials (RCT) comparing different CA approaches were included. Efficacy was defined as arrhythmia recurrence after CA and safety as any reported complication related to the procedure during a minimum follow-up time of 6 months.

RESULTS

In total, 67 RCTs (n = 9871) comparing 19 different CA strategies were included. The risk of recurrence was significantly decreased compared to pulmonary vein isolation (PVI) alone for PVI with renal denervation (RR: 0.60, CI: 0.38-0.94), PVI with ganglia-plexi ablation (RR: 0.62, CI: 0.41-0.94), PVI with additional ablation lines (RR: 0.8, CI: 0.68-0.95) and PVI in combination with bi-atrial modification (RR: 0.32, CI: 0.11-0.88). Strategies including PVI appeared superior to non-PVI strategies such as electrogram-based approaches. No significant differences in safety were observed.

CONCLUSIONS

This NMA showed that PVI in combination with additional CA strategies, such as autonomic modulation and additional lines, seem to increase the efficacy of PVI alone. These strategies can be considered in treating patients with AF, since, additionally, no differences in safety were observed. This study provides decision-makers with comprehensive and comparative evidence about the efficacy and safety of different CA strategies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registry number: CRD42020169494 .

Adjunctive Left Atrial Posterior Wall Isolation in Treating Atrial Fibrillation: Insight From a Large Secondary Analysis

OBJECTIVES

This study evaluated the role of adjunctive left atrium posterior wall isolation (PWI) in preventing atrial fibrillation (AF) recurrence.

BACKGROUND

The left atrium posterior wall is an arrhythmogenic substrate that contributes to the development of AF.

METHODS

This was an updated pooled analysis that included clinical data regarding PWI plus pulmonary vein isolation (PVI) in treating AF. The primary outcome was recurrence of atrial tachyarrhythmias.

RESULTS

A total of 26 studies with 3,287 patients with AF (age 61.7 ± 10.8 years) were included. Mean follow-up was 15.2 ± 8.4 months. Procedural success to achieve PWI was 92.8%. In paroxysmal AF, adjunctive PWI did not reduce the recurrence of all atrial arrhythmias (P = 0.21) or AF (P = 0.37); however, in persistent AF, adjunctive PWI was associated with substantially lower recurrence of all atrial arrhythmias (risk ratio: 0.74; P < 0.001) and AF (risk ratio: 0.67; P = 0.01), particularly when randomized data were included. Subgroup analyses based on meta-regression demonstrated that patients with older age, a larger left atrial diameter, and persistent AF benefited more significantly from the adjunctive PWI. Adjunctive PWI using either radiofrequency or a cryoballoon reduced AF recurrence, whereas using radiofrequency seemed to be associated with higher recurrence rate of atrial tachycardias and/or atrial flutter. Non-BOX adjunctive PWI rather than BOX PWI was associated with significantly lower recurrence of AF. The incidence of procedural adverse events between the PVI+PWI (3.2%) and PVI (2.8%) groups was low and similar. PVI+PWI needed longer ablation and/or procedural time but had similar fluoroscopy time.

CONCLUSIONS

Adjunctive PWI can be achieved in most patients without compromising safety. Patients with persistent AF appear to benefit from this approach. The ablation technology and/or approach may affect the clinical outcome of PWI.

Comparing Efficacy and Safety in Catheter Ablation Strategies for Paroxysmal Atrial Fibrillation: A Network Meta-Analysis of Randomized Controlled Trials

Although catheter ablation (CA) is an established treatment for paroxysmal atrial fibrillation (PAF), there is no consensus regarding the most efficient CA strategy. The objective of this network meta-analysis (NMA) was to compare the efficacy and safety of different CA strategies for PAF. A systematic search was performed in PubMed, Web of Science, and CENTRAL until the final search date, 5 October 2020. Randomised controlled trials (RCT) comparing different CA strategies and methods for pulmonary vein isolation (PVI) were included. Efficacy was defined as lack of arrhythmia recurrence after CA and safety as any reported complication related to the procedure during a minimum follow-up time of six months. In total, 43 RCTs comparing 11 different CA strategies involving 6701 patients were included. The risk of recurrence was significantly decreased in comparison with PVI with radiofrequency only for the following treatments: PVI with adjuvant ablation (RR: 0.79, CI: 0.65–0.97) and PVI with sympathetic modulation (RR: 0.64, CI: 0.46–0.88). However, PVI with radiofrequency was superior to non-PVI strategies (RR: 1.65, CI: 1.2–2.26). No statistically significant difference was found in safety between different CA strategies. Concerning different PVI strategies, no difference was observed either in efficacy or in safety between tested strategies. This NMA suggests that different PVI strategies are generally similar in terms of efficacy, while PVI with additional ablation or sympathetic modulation may be more effective than PVI alone. This study provides decision-makers with insights into the efficacy and safety of different CA strategies.

Contact-Force Guided Posterior Wall Isolation as an Adjunctive Ablation Strategy for Persistent Atrial Fibrillation

Background

The efficacy of posterior wall isolation (PWI) on top of pulmonary vein isolation (PVI) in patients affected by persistent atrial fibrillation (AF) is still controversial and little is known about the impact of contact-force (CF) technology.

Objective

In this retrospective study, we present our experience with PWI using CF sensing catheters and its efficacy and safety as an adjunctive ablation strategy on top of PVI for management of patients with persistent and longstanding persistent AF.

Methods

A total of 73 consecutive patients (20.5% female) affected by persistent atrial fibrillation (10.9% long-standing) underwent PWI as an adjunctive therapy to PVI using CF sensing catheters. Outcomes were reported as incidence of atrial arrhythmic recurrences (ARs) lasting >30 seconds at follow up and in addition, in patients provided with insertable cardiac monitors (ICM), as burden of AF or atrial tachycardias (AT) at relevant time points.

Results

PWI was successfully achieved in 65 (89.0%) patients. Two (2.7%) minor vascular procedural complications were observed. At 1 and 2-year follow-up, ARs free survival was observed in 80.5% and 64.1% of patients, respectively with 75.3% of patients off antiarrhythmic drugs at the last follow-up. Ten patients underwent repeat ablations during the follow-up. At multivariate analysis, early ARs within 3 months after procedure, were associated with a two-fold increased risk of late ARs at follow-up. Among patients provided with ICM, PWI on top of PVI was able to reduce the mean AT/AF burden of more than 50% compared with pre-ablation time, reporting very low levels (≤ 5%) over 2 years.

Conclusions

In persistent atrial fibrillation, PWI on top of PVI using CF sensing catheters is safe and effective, providing great reduction of burden of ARs. Early ARs are associated with a greater risk of late recurrences.

Defibrillation threshold of internal cardioversion prior to ablation predicts atrial fibrillation recurrence

BACKGROUND

Many studies have reported the predictors of atrial fibrillation (AF) recurrence after persistent AF (peAF) ablation. However, the correlation between the atrial defibrillation threshold (DFT) for internal cardioversion (IC) and AF recurrence rate is unknown. Here we investigated the relationship between the DFT prior to catheter ablation for peAF and AF recurrence.

HYPOTHESIS

DFT prior to ablation was the predictive factor for AF recurrence after peAF ablation.

METHODS

From June 2016 to May 2019, we enrolled 82 consecutive patients (mean age, 65.0 ± 12.4 years), including 45 with peAF and 37 with long-standing peAF, at Hamamatsu Medical Center. To assess the DFT, we performed IC with gradually increasing energy prior to radiofrequency application.

RESULTS

Forty-nine and 33 patients showed DFT values less than or equal to 10 J (group A) and greater than 10 J or unsuccessful defibrillation (group B). During the mean follow-up duration of 20.5 ± 13.1 months, patients in group B showed significantly higher AF recurrence rates than those in group A after the ablation procedure (p = .017). Multivariate analysis revealed that DFT was the only predictive factor for AF recurrence (odds ratio, 1.07; 95% CI, 1.00-1.13, p = .047).

CONCLUSIONS

The DFT for IC was among the strongest prognostic factors in the peAF ablation procedure.

Electrical Posterior Box Isolation in Persistent Atrial Fibrillation Changed to Paroxysmal Atrial Fibrillation: A Multicenter, Prospective, Randomized Study

BACKGROUND

Persistent atrial fibrillation (AF) can change to paroxysmal AF after antiarrhythmic drug medication and cardioversion. We investigated whether electrical posterior box isolation (POBI) may improve rhythm outcome of catheter ablation in those patient groups.

METHODS

We prospectively randomized 114 patients with persistent AF to paroxysmal AF (men, 75%; 59.8±9.9 years old) to circumferential pulmonary vein isolation (CPVI) alone group (n=57) and additional POBI group (n=57). Primary end point was AF recurrence after a single procedure, and secondary end points were recurrence pattern, cardioversion rate, and response to antiarrhythmic drugs.

RESULTS

After a mean follow-up of 23.8±10.2 months, the clinical recurrence rate did not significantly differ between the CPVI alone and additional POBI group (31.6% versus 28.1%; P=0.682; log-rank P=0.729). The recurrences as atrial tachycardias (5.3% versus 12.3%; P=0.134) and cardioversion rates (5.3% versus 10.5%; P=0.250) were not significantly different between the CPVI and POBI groups. At the final follow-up, sinus rhythm was maintained without antiarrhythmic drug in 52.6% of CPVI group and 59.6% of POBI group (P=0.450). No significant difference was found in major complication rates between the two groups (5.3% versus 1.8%; P=0.618), but the total ablation time was significantly longer in the POBI group (4187±952 versus 5337±1517 s; P<0.001).

CONCLUSIONS

In patients with persistent AF converted to paroxysmal AF by antiarrhythmic drug, the addition of POBI to CPVI did not improve the rhythm outcome of catheter ablation or influence overall safety, while leading to longer ablation time. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02176616.

Feasibility, Safety, and Efficacy of Posterior Wall Isolation During Atrial Fibrillation Ablation

Background:

The posterior left atrium is an arrhythmogenic substrate that contributes to the initiation and maintenance of atrial fibrillation (AF); however, the feasibility, safety, and efficacy of posterior wall isolation (PWI) as an AF ablation strategy has not been widely reported.

Methods:

We undertook a systematic review and meta-analysis of studies performing PWI to assess (1) acute procedural success including the ability to achieve PWI and the number of procedure-related complications, (2) Long-term, clinical success including rates of arrhythmia recurrence and posterior wall reconnection, and (3) The efficacy of PWI compared with pulmonary vein isolation on preventing arrhythmia recurrence. MEDLINE, EMBASE, and Web of Science databases were searched in May 2018 to retrieve relevant studies. Results were pooled using a random effects model.

Results:

Seventeen studies (13 box isolation, 3 single ring isolation, and 1 debulking ablation) comprising 1643 patients (31.3% paroxysmal AF, left atrial diameter 41±3.1 mm) were included in the final analysis. In studies focusing specifically on PWI, the acute procedural success rate for achieving PWI was 94.1% (95% CI, 87.2%–99.3%). Single-procedure 12-month freedom from atrial arrhythmia was 65.3% (95% CI, 57.7%–73.9%) overall and 61.9% (54.2%–70.8%) for persistent AF. Randomized control trials comparing PWI to pulmonary vein isolation (3 studies, 444 patients) yielded conflicting results and could not confirm an incremental benefit to PWI. Fifteen major complications (0.1%), including 2 atrio-esophageal fistulas, were reported.

Conclusions:

PWI as an end point of AF ablation can be achieved in a large proportion of cases with good rates of 12-month freedom from atrial arrhythmia. Although the procedure-related complication rate is low, it did not eliminate the risk of atrio-esophageal fistula.

Registration:

URL: http://www.crd.york.ac.uk/prospero . PROSPERO registration number: CRD42018107212.

Atrial Fibrillation Mechanisms and Implications for Catheter Ablation

AF is a heterogeneous rhythm disorder that is related to a wide spectrum of etiologies and has broad clinical presentations. Mechanisms underlying AF are complex and remain incompletely understood despite extensive research. They associate interactions between triggers, substrate and modulators including ionic and anatomic remodeling, genetic predisposition and neuro-humoral contributors. The pulmonary veins play a key role in the pathogenesis of AF and their isolation is associated to high rates of AF freedom in patients with paroxysmal AF. However, ablation of persistent AF remains less effective, mainly limited by the difficulty to identify the sources sustaining AF. Many theories were advanced to explain the perpetuation of this form of AF, ranging from a single localized focal and reentrant source to diffuse bi-atrial multiple wavelets. Translating these mechanisms to the clinical practice remains challenging and limited by the spatio-temporal resolution of the mapping techniques. AF is driven by focal or reentrant activities that are initially clustered in a relatively limited atrial surface then disseminate everywhere in both atria. Evidence for structural remodeling, mainly represented by atrial fibrosis suggests that reentrant activities using anatomical substrate are the key mechanism sustaining AF. These reentries can be endocardial, epicardial, and intramural which makes them less accessible for mapping and for ablation. Subsequently, early interventions before irreversible remodeling are of major importance. Circumferential pulmonary vein isolation remains the cornerstone of the treatment of AF, regardless of the AF form and of the AF duration. No ablation strategy consistently demonstrated superiority to pulmonary vein isolation in preventing long term recurrences of atrial arrhythmias. Further research that allows accurate identification of the mechanisms underlying AF and efficient ablation should improve the results of PsAF ablation.

Benefit of Contact Force Sensing Catheter Technology for Successful Left Atrial Anterior Line Formation: A Prospective Randomized Trial

Introduction

The value of contact force information for ablation of LA anterior line is unknown. In a prospective randomized clinical trial, we investigated if information on contact force during left atrial (LA) anterior line ablation reduces total radiofrequency time and results in higher rates of bidirectional line block in patients undergoing pulmonary vein isolation (PVI) plus substrate modification.

Methods

We included patients with indication for pulmonary vein isolation (PVI) and additional substrate modification. For LA anterior line ablation, patients were randomized to contact force information visible (n=35) or blinded (n=37). Patients received contrast enhanced cardiac magnetic resonance imaging (cMRI) before and 3-6 months after ablation to visualize the LA anterior line. Primary endpoint was radiofrequency time to achieve bidirectional line block. Secondary endpoints were completeness of the LA anterior line on cMRI, distribution of contact force, procedural data, adverse events, and 12 months success rate.

Results

In 72 patients (64±9 years, 68% male), bidirectional LA anterior line block was achieved in 70 (97%) patients. Radiofrequency time to bidirectional block did not differ significantly across groups (contact force information visible 23±18min versus contact force information blinded 21±15min, p=0.50). The LA anterior line was discernable on cMRI in 40 patients (82%) without significant differences across randomization groups (p=0.46). No difference in applied contact force was found depending on cMRI line visibility. Twelve-month success and adverse event rates were comparable across groups.

Conclusion

Information on contact force does not significantly improve the ablation of LA anterior lines.

Clinical Trial Registration

The trial was registered at http://www.clinicaltrials.gov by identifier: NCT02217657.

Electrogram characteristics of the coronary sinus in cases requiring epicardial ablation within the coronary sinus for creating a conduction block at the left lateral mitral isthmus

BACKGROUND

Left lateral mitral isthmus (LLMI) linear ablation is a safe and effective technique for treating left mitral flutter. LLMI linear ablation with pulmonary vein isolation may reduce the recurrence of persistent atrial fibrillation. However, epicardial ablation within the coronary sinus (CS) is often required to create the LLMI block line. If the necessity for epicardial ablation is checked before ablation, complications may be reduced.

METHODS

We recruited 135 patients who underwent their first LLMI ablation and divided them into two groups, one group not requiring epicardial ablation for creating a conduction block at the LLMI (Endo group) and another requiring it (Epi group). These two groups were compared in terms of the electrogram characteristics of the CS.

RESULTS

Bidirectional block through the LLMI was achieved in 94.8% of patients. In 42% of these patients, not only the endocardium but also the epicardium was ablated. As for the electrogram, the Endo group had lower atrium voltage and atrioventricular voltage ratios (p = 0.009) than the Epi group before LLMI ablation. By contrast, there were no significant differences in the atrium voltage and the atrioventricular voltage ratio between these two groups after LLMI ablation.

CONCLUSIONS

For creating a conduction block at the LLMI, the atrium voltage and the atrioventricular voltage ratio in the CS before ablation are important. The atrioventricular voltage ratio is a crucial criterion for determining whether epicardial ablation is necessary; furthermore, the atrioventricular voltage ratio in the CS must be reduced with or without epicardial ablation.

Surgical ablation in patients undergoing mitral valve surgery: impact of lesion set and surgical techniques on long-term success

AIMS

To assess the results and impact of lesion set and surgical technique on long-term success of surgical ablation during mitral surgery.

METHODS AND RESULTS

The patient population consisted of 685 subjects with persistent and long-standing persistent atrial fibrillation (AF) undergoing cardiac surgery for mitral valve disease as the primary indication and concomitant ablation between January 2003 and January 2012 at three institutions. One hundred and sixty-six underwent unipolar (24.2%), 371 (54.2%) bipolar, and 148 (21.6%) had combined ablation. Median follow-up was 58.4 months (interquartile range 43.3-67.9). To appropriately account for death, a competing risk model was employed to identify predictors of cumulative incidence of recurrent AF among lesion set and surgical techniques. Eight-year freedom from recurrent arrhythmia without antiarrhythmic drugs was 0.60 ± 0.02. Success rate was higher using bipolar radiofrequency (RF) (P < 0.001), after performing mitral isthmus line (P = 0.003) and following the biatrial technique (P < 0.001). Competing risk regression revealed that use of unipolar RF [sub-hazard ratio (SHR) 2.41 (1.52-3.43), P < 0.001], combined unipolar/bipolar ablation [SHR 1.93 (0.89-2.57), P = 0.003] and the absence of right atrial ablation [SHR 2.79 (1.27-3.48), P < 0.001] were predictors of cumulative incidence of long-term recurrence.

CONCLUSIONS

Our experience suggests that the use of bipolar clamp improves long-term results in surgical treatment of AF and that right-sided ablation should be routinely added. Randomized studies are necessary to confirm our findings.

What have we learned of ablation procedures for atrial fibrillation?

Atrial fibrillation is a widespread disease of growing clinical, economic and social importance. Interventional therapy for atrial fibrillation offers encouraging results, with pulmonary vein isolation (PVI) as the established cornerstone. Yet, the challenge to create durable transmural lesions remains, leading to recurrence of atrial fibrillation in long-term follow-up even after multiple ablation procedures in 20% of patients with paroxysmal atrial fibrillation and approximately 50% with persistent atrial fibrillation. To overcome these limitations, innovative tools such as the cryoballoon and contact force catheters have been introduced and have demonstrated their potential for safe and effective PVI. Furthermore, advanced pharmacological and pacing manoeuvres enhance evaluation of conduction block in PVI.

Electrophysiological Perspectives on Hybrid Ablation of Atrial Fibrillation

To overcome limitations of minimally invasive surgical ablation as a standalone procedure in eliminating atrial fibrillation (AF), hybrid approaches incorporating adjunctive endovascular catheter ablation have been proposed in recent years. The endovascular component targets residual conduction gaps and identifies additional electrophysiological targets with the goal of minimizing recurrent atrial arrhythmia. We performed a systematic review of published studies of hybrid AF ablation, analyzing 432 pooled patients (19% paroxysmal, 29% persistent, 52% long-standing persistent) treated using three different approaches: A. bilateral thoracoscopy with bipolar radiofrequency (RF) clamp-based approach; B. right thoracoscopic suction monopolar RF catheter-based approach; and C. subxiphoid posterior pericardioscopic ("convergent") approach. Freedom from recurrence off antiarrhythmic medications at 12 months was seen in 88.1% [133/151] for A, 73.4% [47/64] for B, and 59.3% [80/135] for C, with no significant difference between paroxysmal (76.9%) and persistent/long-standing persistent AF (73.4%). Death and major surgical complications were reported in 8.5% with A, 0% with B and 8.6% with C. A critical appraisal of hybrid ablation is presented, drawing from experiences and insights published over the years on catheter ablation of AF, with a discussion of the rationale underlying hybrid ablation, its strengths and limitations, where it may have a unique role in clinical management of patients with AF, which questions remain unanswered and areas for further investigation.