STABLE-SR (Electrophysiological Substrate Ablation in the Left Atrium During Sinus Rhythm) for the Treatment of Nonparoxysmal Atrial Fibrillation

Which ablation strategy is the most effective for treating persistent atrial fibrillation? A systematic review and bayesian network meta-analysis of randomized controlled trials

There is no consensus on the most efficient ablation strategy for patients with persistent atrial fibrillation (PerAF). This study aimed to conduct a systematic review and network meta-analysis (NMA) to evaluate the effectiveness of different ablation strategies for PerAF. The primary efficacy outcome was the recurrence of any atrial arrhythmia after a single ablation procedure during the follow-up period. The primary safety outcome of interest was any reported complication related to the procedure. The secondary outcome was the procedure time. Fifty-two studies with 9048 patients were included in this NMA. The studies were conducted between 2004 and 2024, and 22 different ablation strategies were identified. Pulmonary vein isolation + posterior wall box isolation + extra-pulmonary vein isolation was the most effective ablation therapy for PerAF. Most additional substrate modification ablation strategies do not show significant additional benefits. There were no significant differences in the incidence of procedure-related complications between the different ablation strategies. Pulmonary vein isolation combined with additional ablation sites increases the duration of the procedure.

Representation of Women in Atrial Fibrillation Ablation Randomized Controlled Trials: Systematic Review

BACKGROUND

Sex inequality in randomized controlled trials (RCTs) related to cardiovascular disease has been observed. This study examined the proportion of women enrolled in atrial fibrillation (AF) ablation RCTs and the potential risks of underrepresentation of women.

METHODS AND RESULTS

We systematically searched PubMed and Embase for AF ablation RCTs published from 2015 to 2022. Participant characteristics were compared among trials with higher and lower proportions of women. Of 147 AF ablation RCTs (30,055 participants), only 10 trials had enrolled women ≥50% of the total participants. Additionally, 42 trials (28.57%) excluded pregnant/breastfeeding women; 6 (4.1%) excluded reproductive-age women without reliable birth control. The proportion of women in AF RCTs ranged from 9% to 71% (median 31.5%), whereas the median proportion of men was 67.7%. The rate of women included in the trials was stable from 2015 to 2022 (P=0.49). Study characteristics, including funding source, showed no correlation with the rate of inclusion of women. RCTs with a higher proportion of female participants enrolled older patients with AF, had a higher prevalence of hypertension but less persistent AF, and smaller left atrium size (P<0.05 for all). Biological sex was evaluated as a risk factor or in a subgroup analysis in 28 RCTs; 10.7% of these trials observed the implication of sex on their results.

CONCLUSION

Women were underrepresented in contemporary AF ablation RCTs. Additionally, women enrolled in AF RCTs were likely to have more comorbidities but less advanced AF, limiting the applicability of the results to women with AF.

Concomitant pulmonary vein isolation for induced atrial fibrillation to reduce future risk of atrial fibrillation after ablation for isolated atrial flutter

BACKGROUND

A significant proportion of patients with isolated atrial flutter will have atrial fibrillation (AF) after cavotricuspid isthmus (CTI) ablation.

OBJECTIVE

The aim of this study was to determine whether concomitant pulmonary vein isolation (PVI) could reduce the incidence of new-onset AF (NOAF) in the setting of inducible AF after CTI ablation.

METHODS

A total of 275 consecutive patients with isolated atrial flutter who successfully underwent CTI ablation were included. Patients were stratified into the induced AF group (55 patients) and the noninduced AF group (220 patients) on the basis of the inducibility of AF. Subsequently, the induced AF group was randomly divided into a PVI group (28 patients) and non-PVI (27 patients) group.

RESULTS

During 27.0 ± 6.0 months of follow-up, the PVI group (7.1% vs 51.9% [P < .001]; hazard ratio [HR], 0.103 [95% confidence interval for HR, 0.038-0.278; P < .001]) and noninduced AF group (13.2% vs 51.9% [P < .001]); HR, 0.207 [95% confidence interval for HR, 0.073-0.586; P < .001]) exhibited substantially lower incidence and risk of NOAF compared with the non-PVI group. Kaplan-Meier analysis showed that history of hypertension, cardiovascular disease, and heart failure and larger body mass index, larger left atrial diameter, and lower left ventricular ejection fraction were identified predictors of NOAF.

CONCLUSION

Inducibility of AF during CTI ablation is positively associated with an increased risk of NOAF, whereas concomitant PVI for induced AF can significantly reduce the incidence of NOAF.

Integrated Management of Persistent Atrial Fibrillation

The global incidence of atrial fibrillation is on the rise. Atrial fibrillation, a complex disease, heightens the likelihood of heart failure, stroke, and mortality, necessitating careful attention. Controlling heart rate and rhythm, addressing risk factors, and preventing strokes are fundamental in treating atrial fibrillation. Catheter ablation stands out as the primary approach for atrial fibrillation rhythm control. Nevertheless, the limited success rates pose a significant challenge to catheter ablation, particularly for persistent atrial fibrillation. Various adjunctive ablation techniques are currently under investigation to enhance the effectiveness of catheter ablation. This review provides an overview of the current state of the art and the latest optimized treatments for persistent atrial fibrillation in the areas of rhythm control, heart rate control, and risk factor management.

Ablation Strategies for Repeat Procedures in Atrial Fibrillation Recurrences Despite Durable Pulmonary Vein Isolation: The Prospective Randomized ASTRO AF Multicenter Trial

BACKGROUND

Ablation strategies for patients with symptomatic atrial fibrillation and isolated pulmonary veins vary and their effects on arrhythmia recurrence remain unclear. A prospective randomized German multicenter trial sought to compare 2 ablation strategies in this patient cohort.

METHODS

Patients with atrial fibrillation despite durable pulmonary vein isolation were randomly assigned at 7 centers to undergo low-voltage area ablation using 3-dimensional mapping and irrigated radiofrequency current ablation (group A) or empirical left atrial appendage isolation (LAAI) using the cryoballoon followed by staged interventional left atrial appendage closure (group B). The primary end point was freedom from atrial tachyarrhythmias between 91 and 365 days after index ablation. The study was powered for superiority of LAAI compared with low-voltage area.

RESULTS

Patients (40% women; mean age, 68.8±8 years) with paroxysmal (32%) or persistent atrial fibrillation (68%) were randomized to undergo low-voltage area ablation (n=79) or cryoballoon-guided LAAI (n=82). After a planned interim analysis, enrollment was halted for futility on January 10, 2023. In the LAAI group, 77 of 82 left atrial appendages were successfully isolated with subsequent left atrial appendage closure in 57 patients. Procedure-related complications occurred in 4 (5%) and 11 (13.5%) patients in group A and B, respectively (P=0.10). The median follow-up was 367 days (interquartile range, 359-378). The Kaplan-Meier point estimate for freedom from atrial tachyarrhythmias was 51.7% (CI, 40.9%-65.4%) for group A and 55.5% (CI, 44.4%-69.2%; P=0.8069) for group B.

CONCLUSIONS

The current study did not detect superiority of cryoballoon-guided LAAI over low-voltage area ablation in patients with atrial fibrillation despite durable PVI.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04056390.

Evaluating the Prognostic Significance of Cystatin C Level Variations Pre- and Post-Radiofrequency Catheter Ablation in the Recurrence of Persistent Atrial Fibrillation

OBJECTIVE

To investigate the correlation between persistent atrial fibrillation (AF) recurrence and alterations in cystatin C levels pre- and post-radiofrequency catheter ablation (RFCA).

METHODS

This study encompassed 114 patients diagnosed with persistent AF. Their serum cystatin C levels were assessed both prior to and 3 months after undergoing an RFCA procedure. The variance in cystatin C levels before and after RFCA is represented as ΔCystatin C. Subsequently, we compared these values between two groups: patients who did not experience a recurrence of AF (n = 79) and those who did experience a recurrence (n = 35).

RESULTS

A significant reduction in cystatin C levels post-RFCA in both groups, with a more pronounced decrease observed in the non-recurrence group. Moreover, the recurrence group exhibited larger left atrial diameter and volume before RFCA compared to the non-recurrence group. Cox regression analysis indicated that smaller reductions in serum cystatin C levels and greater left atrial volumes before RFCA were associated with an increased risk of recurrence, after adjusting for covariates. The receiver operating characteristic curve indicated an elevated probability of clinical recurrence of AF post-RFCA in patients with a cystatin C decline < 0.08 mg/L (AUC 0.64). The Kaplan-Meier survival analysis revealed that patients with a cystatin C decline > 0.08 mg/L exhibited significantly higher rates of remaining free from recurrence following RFCA across a 24-month follow-up period (Log-rank test p = 0.003).

CONCLUSIONS

Alterations in ΔCystatin C levels pre and post-RFCA in the initial phase could independently predict the recurrence of AF.

Effect of Pulmonary Vein Isolation with Left Atrial Wall Isolation Plus Selective CFAE Ablation in Patients with Persistent Atrial Fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) is a foundational treatment for persistent atrial fibrillation (PeAF), but the effectiveness of adding posterior wall isolation (PWI) and selective complex fractionated atrial electrogram (CFAE) ablation in the roof and anterior wall remains debated. The potential of these additional ablation techniques to improve long-term outcomes for PeAF patients is still uncertain.

METHODS

This retrospective study included 151 PeAF patients who underwent first-time catheter ablation at our center. The choice of ablation strategy was based on the operator's clinical judgment, taking into account the patient's specific condition and anatomical features. Patients were divided into two groups: the PVI group, which received PVI alone, and the modified PWI (MPWI) group, which received PVI along with additional PWI and selective CFAEs ablation in the roof and anterior wall. The primary endpoint was the absence of atrial arrhythmia lasting more than 30 s, without antiarrhythmic drugs, at 12 months.

RESULTS

At the 12-month follow-up, 77.3% of the patients in the MPWI group and 52.1% of the patients in the PVI group remained in sinus rhythm without an atrial arrhythmia recurrence (p = 0.001). The BIC-based Cox regression analysis identified the ablation strategy and atrial fibrillation (AF) duration as independent predictors of recurrence across the cohort. It was found that MPWI significantly reduced the risk of recurrence, while a longer AF duration increased it. In the MPWI group, AF duration, left ventricular internal diameter in systole (LVIDs), and moderate or greater tricuspid regurgitation were independent predictors of recurrence. In the PVI group, only the left atrial low voltage area (LVA) index was a significant predictor.

CONCLUSION

The addition of PWI and selective CFAE ablation to PVI significantly improves 12-month arrhythmia-free survival compared to PVI alone, demonstrating the superiority of this combined approach in improving long-term outcomes for patients with persistent AF.

Representation of obesity in contemporary atrial fibrillation ablation randomized controlled trials

BACKGROUND

The prevalence and impact of obesity on outcomes of atrial fibrillation (AF) ablation randomized controlled trials (RCTs) have not been well studied.

OBJECTIVE

To examine the proportion of participants with obesity enrolled in RCTs of AF ablation and outcomes of ablation when subgroup analysis of participants with obesity were available.

METHODS

We systematically searched PubMed and EMBASE for AF ablation RCTs published between January 1, 2015 to May 31, 2022. When body mass index (BMI) data were available, normal distribution was assumed and a z score was used to estimate the proportion of obesity. Results categorized by BMI or body weight status were reviewed. Authors were contacted for additional information.

RESULTS

Of 148 eligible RCTs with 30174 participants, 144 (97.30%) RCTs did not report the proportion of participants with obesity, while published information regarding BMI was available in 63.51%. Three trials excluded patients based on BMI. Using reported BMI, we estimated the proportion of participants with obesity varied greatly across these trials, ranging from 5.82%-71.9% (median 38.02%, interquartile 29.64%, 49.10%). Patients with obesity were represented in a greater proportion among trials conducted in North America (50.23%) and Asia (44.72%), compared to others (32.16%), p < .001. Subgroup analysis or analysis adjusting for BMI was reported in only 13 (8.78%) RCTs; four (30.77%) of these suggested that BMI or body weight might negatively affect primary outcomes.

CONCLUSION

Obesity is a common comorbidity among AF patients. However, most AF ablation RCTs underreported the proportion of participants with obesity and its impact on the primary outcomes.

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.

The feasibility of atrial Fibrillatory wave amplitude in predicting ablation outcomes in persistent atrial fibrillation

BACKGROUND

Atrial fibrosis has a significant impact on the success rate of catheter ablation (CA) treatment of atrial fibrillation (AF). The fibrotic tissues could be reflected by the amplitude of the fibrillatory wave (F-wave).

METHODS AND RESULTS

704 patients with persistent AF and at least 1-year follow-up after CA were included as the internal group. 101 patients from another hospital were used as the external validation cohort. A 12‑lead ECG was performed before CA and the maximum FWA in three ECG leads (aVL, aVF, V1) were measured. The FWA score (0 to 6 points according to the amplitude range of the three leads) of each patients was calculated. Five models including clinical features, FWA score, CHA2DS2-VASc score, APPLE score and the fusion of clinical features and FWA score were built. The FWA score was superior to the model constructed by clinical variables, CHA2DS2-VASc score and APPLE score. It not only had good predictive performance for AF recurrence, with an AUC value of 0.812 (95% CI 0.724-0.900), but also showed a significant predictive value for the recurrence rate according to F-wave amplitude. In the external validation cohort, the FWA score showed similar results (AUC 0.768, 95% CI 0.672-0.865).

CONCLUSIONS

The present study reveals the significant predictive value of the FWA score for persistent AF ablation recurrence.

A Simple Score to Predict New-Onset Atrial Fibrillation After Ablation of Typical Atrial Flutter

BACKGROUND

New-onset atrial fibrillation (NeAF) is common after cavotricuspid isthmus-dependent counterclockwise atrial flutter (CCW-AFL) ablation. This study aimed to investigate a simple predictive model of NeAF after CCW-AFL ablation.

METHODS

From January 2013, to December 2017, consecutive patients receiving CCW-AFL ablation were enrolled from 3 centres. Clinical, echocardiographic, and electrocardiographic data were collected and followed. Patients from 2 centres and another centre were assigned into the derivation and validation cohorts, respectively. In the derivation cohort, logistic regression was performed to evaluate the ability of parameters to discriminate those with and without NeAF. A score system was developed and then validated.

RESULTS

Two hundred seventy-one patients (mean 59.7 ± 13.6 age; 205 male) were analyzed. During follow-up (73.0 ± 6.5 months), 107 patients (39.5%) had NeAF; 190 and 81 patients were detected in the derivation and validation cohorts, respectively. Hypertension, age ≥ 70 years, left atrial diameter ≥ 42 mm, P-wave duration ≥ 120 ms and the negative component of flutter wave in lead II ≥ 120 ms were selected as the final parameters. A weighted score was used to develop the HAD-AF score ranging from 0 to 9. In the derivation cohort, area under the receiver operating characteristic curve (AUC) was 0.938 (95% confidence interval [CI], 0.902-0.974), superior to those of currently used CHA2DS2-VASC (0.679, 95% CI, 0.600-0.757) and HATCH scores (0.651, 95% CI, 0.571-0.730) (P < 0.001). Performance maintained in the validation cohort.

CONCLUSIONS

Six years after CCW-AFL ablation, 39.5% of patients developed NeAF. HAD-AF score can reliably identify patients likely to develop NeAF after CCW-AFL ablation.

Deep learning-based multimodal fusion of the surface ECG and clinical features in prediction of atrial fibrillation recurrence following catheter ablation

BACKGROUND

Despite improvement in treatment strategies for atrial fibrillation (AF), a significant proportion of patients still experience recurrence after ablation. This study aims to propose a novel algorithm based on Transformer using surface electrocardiogram (ECG) signals and clinical features can predict AF recurrence.

METHODS

Between October 2018 to December 2021, patients who underwent index radiofrequency ablation for AF with at least one standard 10-second surface ECG during sinus rhythm were enrolled. An end-to-end deep learning framework based on Transformer and a fusion module was used to predict AF recurrence using ECG and clinical features. Model performance was evaluated using areas under the receiver operating characteristic curve (AUROC), sensitivity, specificity, accuracy and F1-score.

RESULTS

A total of 920 patients (median age 61 [IQR 14] years, 66.3% male) were included. After a median follow-up of 24 months, 253 patients (27.5%) experienced AF recurrence. A single deep learning enabled ECG signals identified AF recurrence with an AUROC of 0.769, sensitivity of 75.5%, specificity of 61.1%, F1 score of 55.6% and overall accuracy of 65.2%. Combining ECG signals and clinical features increased the AUROC to 0.899, sensitivity to 81.1%, specificity to 81.7%, F1 score to 71.7%, and overall accuracy to 81.5%.

CONCLUSIONS

The Transformer algorithm demonstrated excellent performance in predicting AF recurrence. Integrating ECG and clinical features enhanced the models' performance and may help identify patients at low risk for AF recurrence after index ablation.

Low-Voltage Area Ablation in Addition to Pulmonary Vein Isolation in Patients with Atrial Fibrillation: A Systematic Review and Meta-Analysis

Background: Low-voltage area (LVA) ablation, in addition to pulmonary vein isolation (PVI), has been proposed as a new strategy in patients with atrial fibrillation (AF), but clinical trials have shown conflicting results. We performed a systematic review and meta-analysis to assess the impact of LVA ablation in patient undergoing AF ablation (PROSPERO-registered CRD42024537696). Methods: Randomized clinical trials investigating the role of LVA ablation in addition to PVI in patients with AF were searched on PubMed, Embase, and the Cochrane Library from inception to 22 April 2024. Primary outcome was atrial arrhythmia recurrence after the first AF ablation procedure. Secondary endpoints included procedure time, fluoroscopy time, and procedure-related complication rate. Sensitivity analysis including only patients with LVA demonstration at mapping and multiple subgroups analyses were also performed. Results: 1547 patients from 7 studies were included. LVA ablation in addition to PVI reduced atrial arrhythmia recurrence (odds ratio [OR] 0.65, 95% confidence interval [CI] 0.52-0.81, p < 0.001) with a number needed to treat to prevent recurrence of 10. No difference in procedure time (mean difference [MD] -5.32 min, 95% CI -19.01-8.46 min, p = 0.45), fluoroscopy time (MD -1.10 min, 95% CI -2.48-0.28 min, p = 0.12) and complication rate (OR 0.81, 95% CI 0.40-1.61, p = 0.54) was observed. Consistent results were demonstrated when considering only patients with LVA during mapping and in prespecified subgroups for AF type (paroxysmal vs. persistent), multicentric vs. monocentric trial, and ablation strategy in control group. Conclusions: In patients with AF, ablation of LVAs in addition to PVI reduces atrial arrhythmia recurrence without a significant increase in procedure time, fluoroscopy time, or complication rate.

Association between P-wave terminal force in lead V1 and extent of left atrial low-voltage substrate in older patients with paroxysmal atrial fibrillation

BACKGROUND

The P-wave terminal force in lead V1 (PTFV1) is a marker of cardiomyopathy and risk of atrial fibrillation (AF). Low-voltage area (LVA) in the left atrium (LA), which indicates underlying atrial fibrosis, could predict AF recurrence. This study aimed to investigate the correlation between PTFV1 and LVA in older patients with paroxysmal AF.

METHODS

From May 1, 2020, to October 31, 2021, a total of 162 patients aged 65-80 years with paroxysmal AF who underwent index ablation procedures were enrolled. PTFV1 was measured in sinus rhythm (SR) using 12-lead electrocardiograms prior to the ablation. Abnormal PTFV1 was defined as a ≥ 4 mVms depression. Additional LVA ablation beyond circumferential pulmonary vein isolation (CPVI) was performed if LVAs were found.

RESULTS

Among the 162 patients, 88 had a normal PTFV1 and 74 had an abnormal PTFV1 prior to ablation. There was a significant difference in LVA in patients with and without an abnormal PTFV1 (LVA, 11.0 vs. 5.1 cm2, P < 0.001; LVA burden, 8.9% vs. 4.5%, P < 0.001). PTFV1 and PTAV1 were highest in the upper tertile with extensive LVAs (P < 0.001). Multivariate analysis revealed that abnormal PTFV1 was an independent predictor of LVAs (β = 4.961; 95% CI, 2.135-7.788; P < 0.001). After a median follow-up of 23 months, the AF-free survival rate was similar between the normal PTFV1 group and the abnormal PTFV1 group (13/88 vs. 12/74, hazard ratio [HR], 0.933 [95% CI, 0.425-2.047]; P = 0.861).

CONCLUSIONS

Abnormal PTFV1 at baseline was independently associated with the extent of LVA in older patients with paroxysmal AF.

Failure of intravenous nifekalant cardioversion as an independent predictor for persistent atrial fibrillation recurrence after catheter ablation

AIMS

Nifekalant is a class III antiarrhythmic drug that exerts antiarrhythmic effects by inhibiting rapid rectifying potassium channels and extending the effective refractory period of cardiomyocytes. It has a high success rate in converting atrial fibrillation (AF) to sinus rhythm. Whether the failure of intravenous nifekalant cardioversion is an independent predictor for persistent AF recurrence after catheter ablation has not been reported.

METHODS

A total of 92 patients with drug-refractory persistent AF were retrospectively enrolled. After all ablations, intravenous nifekalant was administrated. Patients were assigned to the success group (group 1) and failure group (group 2) based on nifekalant cardioversion results and followed for 12 months to note any episode of atrial arrhythmia recurrence.

RESULTS

Each group included 46 patients. After 12 months of follow-up, nine (19.6%) patients from group 1 and 23 (50.0%) patients from group 2 had a recurrence of atrial tachyarrhythmia (P = 0.002). AF duration and type 2 diabetes were strongly associated with failure of intravenous nifekalant cardioversion. Univariable Cox proportional hazard regression showed that failure of intravenous nifekalant cardioversion, AF duration, and type 2 diabetes were potential risk factors. Multivariable Cox proportional hazard regression showed that failure of nifekalant cardioversion was statistically associated with AF recurrence (adjusted RR = 2.257, 95% CI: 1.006-5.066, P = 0.048). Failure of intravenous nifekalant cardioversion could bring a positive effect on the prognostic differentiation when added into the multivariable model (0.767 ± 0.042 vs. 0.774 ± 0.045, P = 0.025).

CONCLUSION

Failure of nifekalant cardioversion is an independent predictor for persistent AF recurrence after catheter ablation.

Association between left atrial low-voltage area and induction and recurrence of macroreentrant atrial tachycardia in pulmonary vein isolation for atrial fibrillation

BACKGROUND

The relationship between induction and recurrence due to atrial tachycardia (AT) and left atrial (LA) matrix progression after atrial fibrillation (AF) ablation remains unclear.

METHODS

One hundred fifty-two consecutive patients with paroxysmal and persistent AF who underwent pulmonary vein isolation (PVI) and cavo-tricuspid isthmus (CTI) ablation and achieved sinus rhythm before the procedure were classified into three groups according to the AT pattern induced after the procedure: group N (non-induced), F (focal pattern), and M (macroreentrant pattern) in 3D mapping.

RESULTS

The total rate of AT induction was 19.7% (30/152) in groups F (n = 13) and M (n = 17). Patients in group M were older than those in groups N and F, with higher CHADS2/CHA2DS2-VASc values, left atrial enlargement, and low-voltage area (LVA) size of LA. The receiver operating characteristic curve determined that the cut-off LVA for macroreentrant AT induction was 8.8 cm2 (area under the curve [AUC]: 0.86, 95% confidence interval [CI]: 0.75-0.97). The recurrence of AT at 36 months in group N was 4.1% (5/122), and at the second ablation, all patients had macroreentrant AT. Patients with AT recurrence in group N had a wide LVA at the first ablation, and the cut-off LVA for AT recurrence was 6.5 cm2 (AUC 0.94, 95%CI 0.88-0.99). Adjusted multivariate analysis showed that only LVA size was associated with the recurrence of macroreentrant AT (odds ratio 1.21, 95%CI 1.04-1.51).

CONCLUSIONS

It is important to develop a therapeutic strategy based on the LVA size to suppress the recurrence of AT in these patients.

Mapping-Guided Ablation for Persistent Atrial Fibrillation (MAP-AF): A Multicenter, Single-Blind, Randomized Controlled Trial

BACKGROUND

The clinical outcome of pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF) is suboptimal. Mapping studies have demonstrated atrial sites outside of the pulmonary veins displaying focal activation patterns during AF. We sought to determine whether adding catheter ablation of focal activation sites to PVI improves clinical outcomes of catheter ablation for persistent AF.

METHODS

In this multicenter, randomized, single-blinded trial, we assigned patients with persistent AF to either PVI alone or to mapping-guided ablation of focal activation sites in addition to PVI in a 1:1 ratio. In the mapping-guided group, both atria were mapped after PVI using a Pentaray catheter (Biosense-Webster) and focal activation sites identified by CARTOFINDER (Biosense-Webster) were ablated. The primary end point was freedom from AF or atrial tachycardia without antiarrhythmic drugs beyond a 90-day blanking period.

RESULTS

A total of 98 patients were assigned to the mapping-guided group and 102 to the PVI alone group. In the mapping-guided group, focal activation sites were identified at 2.6±0.3 and 2.5±0.2 sites per patient in the left and right atrium, respectively. Patients were followed up for 768.5 (interquartile range, 723.75-915.75) and 755.5 days (interquartile range, 728.5-913.75) in the mapping-guided ablation and the PVI alone groups, respectively. Freedom from AF/atrial tachycardia without antiarrhythmic drugs at 2-year follow-up was 66.8% and 75.2% in the mapping-guided ablation and the PVI alone groups, respectively (hazard ratio, 1.26 [95% CI, 0.76-2.10]; P=0.37). Adverse events occurred in 3 patients (3.0%) and none (0%) in the mapping-guided ablation and the PVI alone groups, respectively (P=0.12).

CONCLUSIONS

In patients with persistent AF, the addition of mapping-guided ablation of focal activation sites to PVI did not improve clinical outcomes compared with PVI alone.

REGISTRATION

URL: https://center6.umin.ac.jp/cgi-open-bin/ctr/index.cgi?function=02; Unique identifier: UMIN000037569.

Adjunctive low-voltage area ablation for patients with atrial fibrillation: An updated meta-analysis of randomized controlled trials

BACKGROUND

The efficacy and safety of adjunctive low-voltage area (LVA) ablation on outcomes of catheter ablation (CA) for atrial fibrillation (AF) remains uncertain.

METHODS

PubMed, Embase, Cochrane Library, and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) comparing CA with versus without LVA ablation for patients with AF. Risk ratios (RR) with 95% confidence intervals (CI) were pooled with a random-effects model. Our primary endpoint was recurrence of atrial tachyarrhythmia (ATA), including AF, atrial flutter, or atrial tachycardia. We used R version 4.3.1 for all statistical analyses.

RESULTS

Our meta-analysis included 10 RCTs encompassing 1780 patients, of whom 890 (50%) were randomized to LVA ablation. Adjunctive LVA ablation significantly reduced recurrence of ATA (RR 0.76; 95% CI 0.67-0.88; p < .01) and reduced the number of redo ablation procedures (RR 0.54; 95% CI 0.35-0.85; p < .01), as compared with conventional ablation. Among 691 (43%) patients with documented LVAs on baseline substrate mapping, adjunctive LVA ablation substantially reduced ATA recurrences (RR 0.57; 95% CI 0.38-0.86; p < .01). There was no significant difference between groups in terms of periprocedural adverse events (RR 0.78; 95% CI 0.39-1.56; p = .49).

CONCLUSIONS

Adjunctive LVA ablation is an effective and safe strategy for reducing recurrences of ATA among patients who undergo CA for AF.

2023 Cardiac Society of Australia and New Zealand Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has increased exponentially in many developed countries, including Australia and New Zealand. This Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation from the Cardiac Society of Australia and New Zealand (CSANZ) recognises healthcare factors, expertise and expenditure relevant to the Australian and New Zealand healthcare environments including considerations of potential implications for First Nations Peoples. The statement is cognisant of international advice but tailored to local conditions and populations, and is intended to be used by electrophysiologists, cardiologists and general physicians across all disciplines caring for patients with AF. They are also intended to provide guidance to healthcare facilities seeking to establish or maintain catheter ablation for AF.

Evaluation of the effectiveness and safety of a novel substrate-based radiofrequency ablation for persistent atrial fibrillation: a prospective, randomised, parallel-controlled, single-blinded study protocol

INTRODUCTION

Pulmonary vein isolation (PVI) is the cornerstone of radiofrequency (RF) ablation for atrial fibrillation (AF). However, a single ablation strategy does not always achieve the desired therapeutic effect in all patients with persistent AF, and individualised strategies are required for different clinical characteristics.

METHODS AND ANALYSIS

This study aimed to determine the optimal catheter ablation strategy for persistent AF by comparing the efficacy of PVI and BCXL (BC: big circles encircling pulmonary vein isolation; XL: unfixed number of lines based on the left atrial substrate). The BCXL-AF study (clinical trial no. ChiCTR2200067081) was designed as a prospective, randomised, parallel-controlled, single-blinded clinical trial. Overall, 400 patients with persistent AF were randomised in a 1:1 ratio into PVI-only and BCXL-individualised ablation groups. Patients randomised to the individualised ablation group will be further categorised into risk strata according to their clinical condition using the actual ablation method determined by the strata. Seven postoperative visits were conducted from discharge to 24 months of age. The primary observation endpoint will be the incidence of atrial tachyarrhythmia (including AF, atrial flutter and atrial tachycardia with a duration of ≥30 s) without using antiarrhythmic drugs after a blank period of 3 months following a single ablation procedure. The BCXL-AF study will assess an optimal approach for persistent AF RF ablation and evaluate the effectiveness of individualised RF ablation strategies in reducing the recurrence rate of AF.

ETHICS AND DISSEMINATION

The study protocol was reviewed, and ethical approval was obtained from the Army Medical University Human Ethics Committee (approval number: 2022-484-01). All the participants provided written informed consent. This study was conducted according to the principles of the Declaration of Helsinki and its amendments. The results of this study will be disseminated through manuscript publication and conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR2200067081.

Anticoagulation Intensity during Appendage Occlusion: Lessons from Silent Cerebral Embolism

INTRODUCTION

Endovascular left atrial appendage occlusion (LAAO) is associated with a high incidence of peri-procedure silent cerebral embolism (SCE), while the recommended activated clotting time (ACT) level by the expert consensus is lower than that in atrial fibrillation (AF) ablation. The aim of our study was to investigate whether raising the targeted ACT level during LAAO to the same level as AF ablation could decrease the incidence of SCE.

METHODS

It was a prospective observational cohort study. Consecutive AF patients receiving LAAO between January 2021 and December 2022 were included and categorized into two groups based on the time of enrollment. Patients enrolled in 2021 (group 250) maintained a target ACT level of ≥250 s during LAAO procedure, while patients enrolled in 2022 (group 300) maintained the peri-procedure ACT ≥300 s. All patients underwent cerebral magnetic resonance imaging before and after the procedure.

RESULTS

A total of 81 patients were included (38 in the group 250 and 43 in the group 300). After inverse probability of treatment weighting (IPTW), patients in the group 250 showed a significantly lower incidence of SCE than group 300 (IPTW p = 0.038). Only a stable high ACT pattern could decrease the risk of SCE. No significant differences were found between other ACT change patterns on the SCE incidence.

CONCLUSION

Raising the peri-procedure ACT level to a stable 300 s could decrease the risk of the SCE without increasing the major bleeding events.

General anesthesia enhances lesion quality and ablation efficiency of circumferential pulmonary vein isolation

Background

Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. General anesthesia (GA) resolves the problem of pain intolerability and provides regular respiratory mode which might improve the catheter maneuverability of AF ablation. This study aims to compare the procedural performance of PVI under GA versus conscious sedation (CS) from multiple perspectives.

Methods

A total of 36 consecutive patients undergoing first AF ablation under GA were enrolled in GA group. Another 109 patients receiving AF ablation under CS in the same period were selected as the control group. After propensity score matching, 29 matched pairs with similar baseline characteristics were available for further analysis. The AIFV (using AI to analyze the raw data from CARTO3 system) system was used to evaluate six procedural parameters in each PVI procedure.

Results

Compared with CS, PVI under GA had a significantly shorter total PVI time (51.4 min vs. 67.8 min; p = .003) and higher radiofrequency ratio (62.6% vs. 55.8%; p = .032). The number of gaps (1.0 vs. 3.0; p < .001) and the rate of break point were significantly lower in the GA group. GA was also associated with a higher effective ablation-index ratio (87.5% vs. 74.1%; p < .001) and effective force-over-time ratio (85.3% vs. 69.2%; p = .001). After a medium follow-up time of 24 months, 12/29 (41.4%) patients in the CS group and 6/29 (20.7%) patients in the GA group suffered from AF recurrence (p = .156).

Conclusions

GA improves the lesion quality and procedural efficiency of PVI from multiple perspectives evaluated by the AIFV system.

Comparison of clinical outcomes of Ibutilide-guided cardioversion and direct current synchronized cardioversion after radiofrequency ablation of persistent atrial fibrillation

Backgroup

Ibutilide has already been used for cardioversion of persistent atrial fibrillation (PsAF) after radiofrequency catheter ablation (RFCA). The purpose of this study was to determine the effect of Ibutilide-guided cardioversion on clinical outcomes after individualized ablation of PsAF.

Methods

From October 2020 to September 2021, consecutive patients with PsAF accepted for RFCA were prospectively enrolled. After individualized ablation including pulmonary vein isolation plus left atrial roof line ablation and personalized linear ablation based on left atrial low-voltage zones, patients were divided into the spontaneous conversion (SCV) group, direct current synchronized cardioversion (DCC) group and Ibutilide group according to different cardioversion types during ablation. The rates of freedom from atrial tachyarrhythmia (ATT) among the three groups were evaluated after follow-up.

Results

In this study, 110 patients were enrolled, including 12 patients with SCV, 50 patients receiving DCC and 48 patients receiving Ibutilide cardioversion after individualized ablation. Among the three groups, the SCV group had shorter AF duration {12 months [interquartile range (IQR) 12-16], P = 0.042} and smaller left atrial diameter (LAD) [35 mm (IQR: 33-42), P = 0.023]. A 12-month freedom from ATT rate was 83.3% in SCV group, 69.4% in DCC group, and 79.2% in Ibutilide group, respectively (Log-rank, P = 0.745). During the follow-up [17 months (IQR: 15-19)], the rate of freedom from ATT of SCV group (83.3%), and Ibutilide group (72.9%) were both higher than that of DCC group (53.1%, P = 0.042). Moreover, Kaplan-Meier analysis showed a significantly higher sinus rhythm (SR) maintenance in Ibutilide group than in DCC group (Log-rank, P = 0.041). After adjusting for risk factors of AF recurrence, the hazard ratio for AF recurrence of the DCC group with reference to the Ibutilide group was 4.10 [95% confidence interval (CI) (1.87-8.98), P < 0.001]. Furthermore, subgroup analysis showed that freedom from ATT rate in effective Ibutilide subgroup was significantly higher than noneffective Ibutilide subgroup (Log-rank, P < 0.001).

Conclusion

For the treatment of the patients with PsAF, Ibutilide-guided cardioversion after individualized RFCA may be benefit for maintenance of SR compared to conventional DCC, especially for the patients who are effective for administration of Ibutilide.

Functional mapping to reveal slow conduction and substrate progression in atrial fibrillation

AIMS

The aim of our study was to analyse the response to short-coupled atrial extrastimuli to identify areas of hidden slow conduction (HSC) and their relationship with the atrial fibrillation (AF) phenotype.

METHODS AND RESULTS

Twenty consecutive patients with paroxysmal AF and persistent AF (10:10) underwent the first pulmonary vein isolation procedure. Triple short-coupled extrastimuli were delivered in sinus rhythm (SR), and the evoked response was analysed: sites exhibiting double or highly fragmented electrograms (EGM) were defined as positive for HSC (HSC+). The delta of the duration of the bipolar EGM was analysed, and bipolar EGM duration maps were built. High-density maps were acquired using a multipolar catheter during AF, SR, and paced rhythm. Spatial co-localization of HSC+ and complex fractionated atrial EGMs (CFAE) during AF was evaluated. Persistent AF showed a higher number and percentage of HSC+ than paroxysmal AF (13.9% vs. 3.3%, P < 0.001). The delta of EGM duration was 53 ± 22 ms for HSC+ compared with 13 ± 11 (10) ms in sites with negative HSC (HSC-) (P < 0.001). The number and density of HSC+ were lower than CFAE during AF (19 vs. 56 per map, P < 0.001). The reproducibility and distribution of HSC+ in repeated maps were superior to CFAE (P = 0.19 vs. P < 0.001). Sites with negative and positive responses showed a similar bipolar voltage in the preceding sinus beat (1.65 ± 1.34 and 1.48 ± 1.47 mV, P = 0.12).

CONCLUSION

Functional mapping identifies more discrete and reproducible abnormal substrates than mapping during AF. The HSC+ sites in response to triple extrastimuli are more frequent in persistent AF than in paroxysmal AF.

Left atrial total emptying fraction measured by cardiovascular magnetic resonance imaging predicts low-voltage areas detected during electroanatomical mapping

AIMS

Low-voltage areas (LVAs) found during left atrial (LA) electroanatomical mapping are increasingly targeted by radiofrequency catheter ablation (RFCA) on top of pulmonary vein isolation to improve arrhythmia-free survival in patients with atrial fibrillation (AF). However, pre-procedural prediction of LVAs remains challenging. The purpose of the present study was to describe the association between parameters of LA function and dimensions, respectively, derived from pre-procedural cardiovascular magnetic resonance (CMR) imaging, and the presence of LVAs on LA voltage mapping.

METHODS AND RESULTS

Patients who underwent first-time RFCA for paroxysmal or persistent AF and who were in stable sinus rhythm during pre-procedural CMR imaging were included in this study. Cardiovascular magnetic resonance-derived parameters of LA function and dimensions were calculated. Low-voltage areas were defined as areas with bipolar voltage amplitudes of ≤0.5 mV on electroanatomical mapping. In total, 259 consecutive patients were included in this analysis. Low-voltage areas were found in 25 of 259 patients (9.7%). Compared with those without LVAs, patients with LVAs were significantly older, were more likely to be female, had a higher CHA2DS2-VASc score, had larger LA volumes, and had a lower LA total emptying fraction (TEF). In multivariate analysis, only LA TEF [odds ratio (OR) 0.885, 95% confidence interval (CI) 0.846-0.926, P < 0.001] and the CHA2DS2-VASc score (OR 1.507, 95% CI 1.115-2.038, P = 0.008) remained independently associated with the presence of LVAs.

CONCLUSION

Left atrial TEF and the CHA2DS2-VASc score were independently associated with the presence of LVAs found during LA electroanatomical mapping. These findings may help to improve pre-procedural prediction of pro-arrhythmogenic LVAs and to improve peri-procedural patient management.

Dynamic changes of left atrial substrate over time following pulmonary vein isolation: the Progress-AF study

AIMS

Little is known about dynamic changes of the left atrial (LA) substrate over time in patients with atrial fibrillation (AF). This study aims to evaluate substrate changes following pulmonary vein isolation (PVI).

METHODS AND RESULTS

In our prospective observational study, consecutive patients undergoing first PVI-only and redo ablation were included. High-density maps of the two procedures were compared. Progression or regression was diagnosed if a significant concordant decrease or increase in bipolar voltages in ≥2 segments was observed, respectively. In 28 patients (61.2 ± 9.5 years, 39% female, 53.5% persistent AF), 111.013 voltage points from 56 high-density LA maps (1.982 points/patient) were analysed. Comparing the high-density maps of the first and second procedures, in the progression group (17 patients, 61%), there was a decrease in global (-35%, P < 0.001) and all regional voltages. In the regression group (11 patients, 39%), there was an increase in global (+43%, P < 0.001) and regional voltages. Comparing the progression with the regression group, the area of low-voltage zone (LVZ) increased (+3.5 vs. -4.5 cm2, P < 0.001) and LA activation time prolonged (+8.0 vs. -9.1 ms, P = 0.005). Baseline clinical parameters did not predict progression or regression. In patients with substrate progression, pulmonary veins (PVs) were more frequently isolated (P = 0.02) and the AF pattern at recurrence was more frequently persistent (P = 0.005).

CONCLUSION

Our study describes bidirectional dynamic properties of the LA substrate with concordant either progressive or regressive changes. Regression occurs with reduced AF burden after the first procedure, while progression is associated with persistent AF recurrence despite durable PV isolation. The dynamic nature of LA substrate poses questions about LVZ-based ablation strategies.

Persistent left superior vena cava isolation in patients with atrial fibrillation: Selective or empirical?

BACKGROUND

Persistent left superior vena cava (PLSVC) is the most prevalent form of thoracic venous abnormality and can serve as a significant arrhythmogenic source in atrial fibrillation (AF).

METHODS AND RESULTS

Among the 3950 patients who underwent radiofrequency ablation for AF between September 2014 to April 2020, 17 patients (mean age 59.4 ± 8.0 years, 64.7% male) with PLSVC were identified. Among them, nine patients (52.9%) had a prior history of pulmonary vein isolation (PVI) alone. Eight out of nine patients who experienced AF recurrence underwent PLSVC isolation with or without pulmonary vein (PV) reconnection. For the remaining eight patients (47.1%), PVI plus PLSVC isolation were performed during the index procedure. Ectopy originating from PLSVC was documented in 11 patients (64.7%) and successful PLSVC isolation was achieved in 16 patients (94.1%). After a median follow-up of 28.3 months, freedom from AF/ atrial tachycardia (AT) was observed in 13 patients (76.5%).

CONCLUSION

Empirical PLSVC isolation beyond PVI appears to be a feasible and safe strategy to prevent AF recurrence in patients with concomitant PLSVC.

No Effect of Continued Antiarrhythmic Drug Treatment on Top of Optimized Pulmonary Vein Isolation in Patients With Persistent Atrial Fibrillation: Results From the POWDER-AF2 Trial

BACKGROUND

In patients with persistent atrial fibrillation (PersAF), catheter ablation aiming for pulmonary vein isolation (PVI) is associated with moderate clinical effectiveness. We investigated the benefit of continuing previously ineffective class 1C or 3 antiarrhythmic drug therapy (ADT) in the setting of a standardized PVI-only ablation strategy.

METHODS

In this multicenter, randomized controlled study, patients with PersAF (≥7 days and <12 months) despite ADT were prospectively randomized 1:1 to PVI with ADT continued versus discontinued beyond the blanking period (ADT ON versus ADT OFF). Standardized catheter ablation was performed aiming for durable isolation with stable, contiguous, and optimized radio frequency applications encircling the pulmonary veins (CLOSE protocol). Clinical visits and 1-to-7-day Holter were performed at 3, 6, and 12 months. The primary end point was any documented atrial tachyarrhythmia lasting >30 seconds beyond 3 months. Prospectively defined secondary end points included repeat ablations, unscheduled arrhythmia-related visits, and quality of life among groups.

RESULTS

Of 200 PersAF patients, 98 were assigned to ADT OFF and 102 to ADT ON. The longest atrial fibrillation episode qualifying for PersAF was 28 (10-90) versus 30 (11-90) days. Clinical characteristics and procedural characteristics were similar. Recurrence of atrial tachyarrhythmia was comparable in both groups (20% OFF versus 21.2% ON). No differences were observed in repeat ablations and unscheduled arrhythmia-related visits. Marked improvement in quality of life was observed in both groups.

CONCLUSIONS

In patients with PersAF, there is no benefit in continuing previously ineffective ADT beyond the blanking period after catheter ablation. The high success rate of PVI-only might be explained by the high rate of durable isolation after optimized PVI and the early stage of PersAF (POWDER-AF2).

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03437356.

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.

Right atrial tachycardia after atrial fibrillation ablation: prevalence, clinical characteristics, electrophysiological mechanisms, and long-term outcomes

BACKGROUND

This study aims to evaluate the prevalence, clinical characteristics, electrophysiological mechanisms, and long-term outcomes of right atrial tachycardia (AT) in patients who underwent ablation for atrial fibrillation (AF).

METHODS

From March 2010 to December 2020, 220 consecutive patients undergoing index AF ablation were referred for post-ablation AT recurrence. Thirty-five patients (35/220, 15.9%) with right AT recurrence (25 men; mean age 59.3 ± 10.2 years) were enrolled. These patients were divided into groups with right ATs exclusively (group 1) and right combined with left ATs (group 2).

RESULTS

Fifty-three ATs were mapped in all patients, with thirty-nine ATs originating from the right atrium. The detailed distribution of all right ATs was 22 in the cavo-tricuspid isthmus (CTI), 6 in the ostium of superior vein cava (SVC), 4 in the right free wall, 4 in the right anterior atrial septum, 2 in coronary sinus ostium, and 1 in crista terminalis. Group 2 had a significantly higher incidence of typical atrial flutter (AFL) than group 1 (11/12, 90.9% vs. 12/24, 50.0%, P = 0.03). During the mean follow-up of 43.6 ± 25.2 months after the index AT ablation, the recurrence rate of AT/AF was 22.9% (8/35), and it was lower in group 1 than in group 2 (8.3% vs. 54.5%, P = 0.01).

CONCLUSION

Right AT is relatively less common post-AF ablation. The CTI-dependent AFL and the ostium of SVC-derived focal AT constituted the major components of right ATs, suggesting the importance of ablation- and anatomy-related arrhythmogenic effects in the right atrium.

Gender Differences in Atrial Fibrosis and Cardiomyopathy Assessed by Left Atrial Low-Voltage Areas During Catheter Ablation of Atrial Fibrillation

Atrial myocardial degeneration predisposes to atrial fibrillation (AF), ischemic stroke, and heart failure. Studies suggest the presence of gender differences in atrial myocardial degeneration. This study aimed to delineate gender differences in the prevalence, predictors, and prognostic impact of left atrial low-voltage areas (LVAs). This observational study included 1,488 consecutive patients who underwent initial ablation for AF. Voltage mapping was performed after pulmonary vein isolation during sinus rhythm. LVAs were defined as regions where bipolar peak-to-peak voltage was <0.50 mV. LVA prevalence was higher in women (38.7%) than in men (16.0%). High age, persistent form of AF, diabetes mellitus, and a large left atrium were shown to be common predictors in both gender categories. Heart failure and history of stroke/thromboembolic events were men-specific predictors of LVA existence. Women experienced more AF recurrence than men (31.1% vs 25.7%, p = 0.027). LVA existence was significantly associated with increased AF recurrence in each gender category, with a respective hazard ratio, 95% confidence interval, and p value of 2.45, 1.87 to 3.22, and <0.0001 in men and 1.82, 1.33 to 2.49, and <0.0001 in women. In conclusion, LVA was more frequent in women than men, and predicted frequent AF recurrence irrespective of gender category.

What determines the optimal pharmacological treatment of atrial fibrillation? Insights from in silico trials in 800 virtual atria

The best pharmacological treatment for each atrial fibrillation (AF) patient is unclear. We aim to exploit AF simulations in 800 virtual atria to identify key patient characteristics that guide the optimal selection of anti-arrhythmic drugs. The virtual cohort considered variability in electrophysiology and low voltage areas (LVA) and was developed and validated against experimental and clinical data from ionic currents to ECG. AF sustained in 494 (62%) atria, with large inward rectifier K+ current (IK1 ) and Na+ /K+ pump (INaK ) densities (IK1 0.11 ± 0.03 vs. 0.07 ± 0.03 S mF-1 ; INaK 0.68 ± 0.15 vs. 0.38 ± 26 S mF-1 ; sustained vs. un-sustained AF). In severely remodelled left atrium, with LVA extensions of more than 40% in the posterior wall, higher IK1 (median density 0.12 ± 0.02 S mF-1 ) was required for AF maintenance, and rotors localized in healthy right atrium. For lower LVA extensions, rotors could also anchor to LVA, in atria presenting short refractoriness (median L-type Ca2+ current, ICaL , density 0.08 ± 0.03 S mF-1 ). This atrial refractoriness, modulated by ICaL and fast Na+ current (INa ), determined pharmacological treatment success for both small and large LVA. Vernakalant was effective in atria presenting long refractoriness (median ICaL density 0.13 ± 0.05 S mF-1 ). For short refractoriness, atria with high INa (median density 8.92 ± 2.59 S mF-1 ) responded more favourably to amiodarone than flecainide, and the opposite was found in atria with low INa (median density 5.33 ± 1.41 S mF-1 ). In silico drug trials in 800 human atria identify inward currents as critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics. KEY POINTS: Atrial fibrillation (AF) maintenance is facilitated by small L-type Ca2+ current (ICaL ) and large inward rectifier K+ current (IK1 ) and Na+ /K+ pump. In severely remodelled left atrium, with low voltage areas (LVA) covering more than 40% of the posterior wall, sustained AF requires higher IK1 and rotors localize in healthy right atrium. For lower LVA extensions, rotors can also anchor to LVA, if the atria present short refractoriness (low ICaL ) Vernakalant is effective in atria presenting long refractoriness (high ICaL ). For short refractoriness, atria with fast Na+ current (INa ) up-regulation respond more favourably to amiodarone than flecainide, and the opposite is found in atria with low INa . The inward currents (ICaL and INa ) are critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics.

Differences in atrial substrate localization using late gadolinium enhancement-magnetic resonance imaging, electrogram voltage, and conduction velocity: a cohort study using a consistent anatomical reference frame in patients with persistent atrial fibrillation

AIMS

Electro-anatomical voltage, conduction velocity (CV) mapping, and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) have been correlated with atrial cardiomyopathy (ACM). However, the comparability between these modalities remains unclear. This study aims to (i) compare pathological substrate extent and location between current modalities, (ii) establish spatial histograms in a cohort, (iii) develop a new estimated optimized image intensity threshold (EOIIT) for LGE-MRI identifying patients with ACM, (iv) predict rhythm outcome after pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF).

METHODS AND RESULTS

Thirty-six ablation-naive persistent AF patients underwent LGE-MRI and high-definition electro-anatomical mapping in sinus rhythm. Late gadolinium enhancement areas were classified using the UTAH, image intensity ratio (IIR >1.20), and new EOIIT method for comparison to low-voltage substrate (LVS) and slow conduction areas <0.2 m/s. Receiver operating characteristic analysis was used to determine LGE thresholds optimally matching LVS. Atrial cardiomyopathy was defined as LVS extent ≥5% of the left atrium (LA) surface at <0.5 mV. The degree and distribution of detected pathological substrate (percentage of individual LA surface are) varied significantly (P < 0.001) across the mapping modalities: 10% (interquartile range 0-14%) of the LA displayed LVS <0.5 mV vs. 7% (0-12%) slow conduction areas <0.2 m/s vs. 15% (8-23%) LGE with the UTAH method vs. 13% (2-23%) using IIR >1.20, with most discrepancies on the posterior LA. Optimized image intensity thresholds and each patient's mean blood pool intensity correlated linearly (R2 = 0.89, P < 0.001). Concordance between LGE-MRI-based and LVS-based ACM diagnosis improved with the novel EOIIT applied at the anterior LA [83% sensitivity, 79% specificity, area under the curve (AUC): 0.89] in comparison to the UTAH method (67% sensitivity, 75% specificity, AUC: 0.81) and IIR >1.20 (75% sensitivity, 62% specificity, AUC: 0.67).

CONCLUSION

Discordances in detected pathological substrate exist between LVS, CV, and LGE-MRI in the LA, irrespective of the LGE detection method. The new EOIIT method improves concordance of LGE-MRI-based ACM diagnosis with LVS in ablation-naive AF patients but discrepancy remains particularly on the posterior wall. All methods may enable the prediction of rhythm outcomes after PVI in patients with persistent AF.

Circumferential Pulmonary Vein Isolation With vs Without Additional Low-Voltage-Area Ablation in Older Patients With Paroxysmal Atrial Fibrillation: A Randomized Clinical Trial

Importance

The overall success rate of circumferential pulmonary vein isolation (CPVI) treatment in patients with paroxysmal atrial fibrillation (AF) remains suboptimal, especially in older patients.

Objective

To explore the incremental benefit of low-voltage-area ablation after CPVI in older patients with paroxysmal AF.

Design, Setting, and Participants

This randomized clinical trial was an investigator-initiated trial to compare the efficacy of additional low-voltage-area ablation beyond CPVI vs CPVI alone in older patients with paroxysmal AF. Participants were patients aged 65 to 80 years with paroxysmal AF who were referred for catheter ablation. They were enrolled in 14 tertiary hospitals in China from April 1, 2018, to August 3, 2020, and follow-up occurred through August 15, 2021.

Interventions

Patients were randomized (1:1) to undergo CPVI plus low-voltage-area ablation or CPVI alone. Low-voltage areas were defined as areas with amplitude less than 0.5 mV in more than 3 adjacent points. If low-voltage areas existed, additional substrate ablation was performed in the CPVI plus group but not the CPVI alone group.

Main Outcomes and Measures

The primary end point of the study was freedom from atrial tachyarrhythmia as documented by electrocardiogram during a clinical visit or lasting longer than 30 seconds during Holter recordings occurring after a single ablation procedure.

Results

Among 438 patients who were randomized (mean [SD] age, 70.5 [4.4] years; 219 men [50%]), 24 (5.5%) did not complete the blanking period and were not included for efficacy analysis. After a median follow-up of 23 months, the recurrence rate of atrial tachyarrhythmia was significantly lower in the CPVI plus group (31/209 patients, 15%) compared with the CPVI alone group (49/205, 24%; hazard ratio [HR], 0.61; 95% CI, 0.38-0.95; P = .03). In subgroup analyses, among all patients with low-voltage area, CPVI plus substrate modification was associated with a 51% decreased risk of ATA recurrence compared with CPVI alone (HR, 0.49; 95% CI, 0.25-0.94; P = .03).

Conclusions and Relevance

This study found that additional low-voltage-area ablation beyond CPVI decreased the ATA recurrence in older patients with paroxysmal AF compared with CPVI alone. Our findings merit further replication by larger trials with longer follow-up.

Trial Registration

ClinicalTrials.gov Identifier: NCT03462628.

Plasma 8-Hydroxy-2'-Deoxyguanosine, a Potential Valuable Biomarker for Atrial Fibrosis Is Influenced by Polymorphism of DNA Methylation Gene

BACKGROUND

Previous studies revealed a relationship between 8-hydroxy-2'-deoxyguanosine (8-OHdG) and the occurrence/recurrence of atrial fibrillation (AF). This 2-part study aimed to validate whether DNA damage related to 8-OHdG is associated with left atrial (LA) fibrosis in AF patients quantified by voltage mapping (Part I), and to identify the underlying genetic components regulating the 8-OHdG level (Part II).

METHODS AND RESULTS

Plasma 8-OHdG determination, DNA extraction, and genotyping were conducted before catheter ablation. LA voltage mapping was performed under sinus rhythm. According to the percentage of low voltage area (LVA), patients were categorized as stage I (<5%), stage II (5-10%), stage III (10-20%), and stage IV (>20%). Part I included 209 AF patients. The 8-OHdG level showed an upward trend together with advanced LVA stage (stage I 8.1 [6.1, 10.5] ng/mL, stage II 8.5 [5.7, 14.1] ng/mL, stage III 14.3 [12.1, 16.5] ng/mL, stage IV 13.9 [10.5, 16.0] ng/mL, P<0.000). Part II included 175 of the 209 patients from Part I. Gene-set analysis based on genome-wide association study summary data identified that the gene set named 'DNA methylation on cytosine' was the only genetic component significantly associated with 8-OHdG concentration.

CONCLUSIONS

Higher 8-OHdG levels may predict more advanced LVA of the LA in AF patients. DNA methylation is the putative genetic component underlying oxidative DNA damage in AF patients.

Left atrial appendage occlusion combined with cryoballoon or radiofrequency ablation: One-year follow-up comparison

Background

A one-stop procedure involving catheter ablation and left atrial appendage occlusion (LAAO) is an option for high-risk atrial fibrillation patients. Few studies have reported the efficacy and safety of cryoballoon ablation (CBA) combined with LAAO, and no studies have compared the combination of LAAO with CBA or radiofrequency ablation (RFA).

Methods

A total of 112 patients were enrolled in the present study; 45 patients received CBA combined with LAAO (group 1), and 67 patients received RFA combined with LAAO (group 2). Patient follow-up was performed for 1 year to detect peri-device leaks (PDLs) and safety outcomes (defined as a composite of peri-procedural and follow-up adverse events).

Results

The number of PDLs at the median 59 days follow-up was comparable between the two groups (33.3% in group 1 vs. 37.3% in group 2, p = 0.693). Safety outcomes were also comparable between the two groups (6.7% in group 1 vs. 7.5% in group 2, p = 1.000). Multivariable regression showed that PDLs risk and safety outcomes were all similar between the two groups. Subgroup analysis of PDLs indicated no significant differences. Follow-up safety outcomes were related to anticoagulant medication, and patients without PDLs were more likely to discontinue antithrombotic therapy. The total procedure and ablation times were all significantly shorter for group 1.

Conclusion

When compared with left atrial appendage occlusion combined with radiofrequency, left atrial appendage occlusion combined with cryoballoon ablation has the same risk of peri-device leaks and safety outcomes, but the procedure time was significantly reduced.

Differences in postablation cardiac MRI scar between radiofrequency and cryoballoon ablation: A DECAAF II subanalysis

INTRODUCTION

Pulmonary vein isolation (PVI) using radiofrequency (RF) and cryoballoon (Cryo) ablation are standard approaches for rhythm control in patients with symptomatic atrial fibrillation. Both strategies create scars in the left atrium (LA). There have been few studies investigating the difference in scar formation between patients undergoing RF and Cryo using cardiac magnetic resonance (CMR) imaging.

METHODS

The current study is a subanalysis of the control arm of the Delayed-Enhancement MRI Determinant of Successful Catheter Ablation of Atrial Fibrillation study (DECAAF II). The study was a multicenter, randomized, controlled, single-blinded trial that evaluated atrial arrhythmia recurrence (AAR) between PVI alone and PVI plus CMR atrial fibrosis-guided ablation. Preablation CMR and 3- to 6-month postablation CMR were obtained to assess baseline LA fibrosis and scar formation, respectively.

RESULTS

Of the 843 patients randomized in the DECAAF II trial, we analyzed the 408 patients in the primary analysis control arm that received standard PVI. Five patients received combined RF and Cryo ablations, so they were excluded from this subanalysis. Of the 403 patients analyzed, 345 underwent RF and 58 Cryo. The average procedure duration was 146 min for RF and 103 min for Cryo (p = .001). The rate of AAR at ~15 months occurred in 151 (43.8%) patients in the RF group and 28 (48.3%) patients in the Cryo group (p = .62). On 3-month post-CMR, the RF arm had significantly more scar (8.8% vs. 6.4%, p = .001) compared to Cryo. Patients with ≥6.5% LA scar (p < .001) and ≥2.3% LA scar around the PV antra (p = .01) on 3-month post-CMR had less AAR independent of the ablation technique. Cryo caused a greater percentage of right and left pulmonary vein (PV) antral scar (p = .04, p = .02) and less non-PV antral scar (p = .009) compared to RF. On Cox regression, Cryo patients free of AAR had a greater percentage of left PV antral scar (p = .01) and less non-PV antral scar (p = .004) compared to RF free of AAR.

CONCLUSION

In this subanalysis of the control arm of the DECAAF II trial, we observed that Cryo formed a more significant percentage of PV antral scar and less non-PV antral scar compared to RF. Post ablation LA scar ≥6.5% predicted freedom from AAR, independent of ablation technique. These findings may have prognostic implications in ablation technique selection and freedom from AAR.

Characterization and identification of atrial fibrillation drivers in patients with nonparoxysmal atrial fibrillation using simultaneous amplitude frequency electrogram transform

INSTRUCTION

We hypothesized that real-time simultaneous amplitude frequency electrogram transform (SAFE-T) during sinus rhythm (SR) is able to identify and characterize the drivers of atrial fibrillation (AF) in nonparoxysmal (NP) AF.

METHODS

Twenty-one NPAF patients (85.71% males, mean age 52 years old) underwent substrate mapping during SR (SAFE-T and voltage) and during AF (complex fractionated atrial electrograms [CFAE] and similarity index [SI]). After pulmonary veins isolation, extensive substrate ablation was performed with the endpoint of procedural termination or elimination of all SI sites (>63% similarities). Sites with procedural termination and non-termination sites were tagged for postablation SR analysis using SAFE-T.

RESULTS

In 74 CFAE sites identified (average of 3 ± 2 sites per person), 28 (37.84%) were identified as termination sites demonstrating a high SI compared with the non-termination sites (80.11 ± 9.57% vs. 45.96 ± 13.38%, p < .001) during AF. During SR, these termination sites have high SAFE-T values and harbor a highly resonant, localized, repetitive high frequency components superimposed in the low frequency components compared with non-termination sites (5.70 ± 3.04 vs. 1.49 ± 1.66 Hz·mV, p < .001). In the multivariate analysis, the termination sites have higher SAFE-T and SI value (p < .001).

CONCLUSION

AF procedural termination sites harbored signal characteristics of repetitive, high frequency component of individualized electrogram during SR, which can be masked by the low frequency fractionated electrogram and are difficult to see from the bipolar electrogram. Thus, SAFE-T mapping is feasible in identifying and characterizing sites of AF drivers.

The utility of combining continuous wavelet transform analysis and high-density voltage map in predicting the long-term outcomes after ablation of persistent atrial fibrillation

BACKGROUND

Continuous wavelet transform (CWT) analysis is a frequency analysis to detect areas of stable high-frequent activity (stable pseudo frequency [sPF]) during atrial fibrillation (AF). As previously reported, patients with the highest sPF area in pulmonary veins (PV) showed better short-term outcomes after PV isolation (PVI). This study sought to evaluate the efficacy of CWT analysis in predicting the long-term (2 years) outcomes after PVI. We also combined the left atrial (LA) voltage map with CWT analysis to further predict the outcome.

METHODS

Persistent AF patients (n = 109, age 65 ± 10) underwent a CWT analysis at PVs and 8 LA sites during AF for pre-PVI analysis. After PVI during AF, CWT analysis was performed again in the LA as post-PVI analysis and was compared with pre-PVI analysis. A sinus voltage map of LA was created after cardioversion.

RESULTS

Seventy patients had the highest sPF within PVs (PV-dominant group), while 39 patients had the highest sPF outside PVs (LA-dominant group). The global frequency in the LA showed a significant decrease after PVI only in PV-dominant group (6.55 ± 0.27 to 6.43 ± 0.37, P < 0.01). AF-free survival was better in PV-dominant group than LA-dominant group at 2-year follow-up (87.1% vs. 64.3%, P < 0.002). This trend was recognized throughout all degrees of low voltage area in the LA (LA-LVA), and AF-free survival was well predicted by combining CWT analysis and LA-LVA.

CONCLUSIONS

By combining CWT analysis and sinus LA-LVA, the long-term AF-free survival after PVI was well stratified and predicted.

Randomized evaluation of redo ablation procedures of atrial fibrillation with focal impulse and rotor modulation-guided procedures: the REDO-FIRM study

AIMS

REDO-FIRM evaluated safety and effectiveness of conventional vs. focal impulse and rotor modulation (FIRM)-guided ablation of recurrent persistent or paroxysmal atrial fibrillation (AF) after an initial AF ablation procedure.

METHODS AND RESULTS

This prospective, multicentre, randomized study included patients with a single prior AF ablation, but with recurrent AF and reconnected pulmonary veins (PVs). Conventional ablation generally included PV re-isolation; however, additional ablation was permitted per physician discretion. In the FIRM arm, beyond PV re-isolation, basket catheter-based FIRM mapping created dynamic animations of putative rotors, which were targeted for ablation. Between May 2016 and July 2019, 269 subjects were randomized, with 243 subjects completing 12-month follow-up. Ablation beyond re-pulmonary vein isolation, the FIRM vs. Conventional arms did not differ significantly: cavo-tricuspid isthmus -9.0% vs. 15.3%, caval vein isolation -1.5% vs. 0.8%, non-PV trigger -2.2% vs. 3.8%, other -11.9% vs. 13.0%. Single procedure 12-month freedom from AF/atrial tachycardia/atrial flutter-recurrence was 63.3% (76/120) vs. 59.0% (72/122) in the FIRM and Conventional arms (P = 0.3503). Efficacy was similar in the paroxysmal and persistent AF subgroups (P = 0.22 and P = 0.48). The 10-day and 12-month safety endpoints were achieved in 93.3% vs. 93.8% (P = 0.89) and 88.4% vs. 93.4% (P = 0.22) in the FIRM and Conventional arms, respectively.

CONCLUSIONS

In REDO-FIRM, as compared to standard ablation, FIRM-guided ablation did not provide additional efficacy in redo ablation procedures, but FIRM-guided ablation was equally safe. Additional studies are necessary to identify any potential population able to benefit from FIRM-guided ablation.

Use of a two-handed model to improve comprehension of ventricular outflow tract anatomy

BACKGROUND

Mastering cardiac anatomy is a formidable obstacle in the learning process for cardiac electrophysiology trainees. The complex three-dimensional characteristics and contiguous relationship of the ventricular outflow tract are particularly difficult to visualize with the limited study methods available. The hands can recreate a morphology similar to the ventricular outflow tract; this study explored whether a two-handed model of the heart helps electrophysiology trainees improve their understanding of ventricular outflow tract anatomy.

METHODS

After an initial assessment, trainees were randomly placed into variable and control groups. Subsequently, all trainees learned the outflow tract anatomy using routine methods, with the variable group receiving additional instruction using the two-handed model. One day and one week after the course conclusion, knowledge of the ventricular outflow tract anatomy was assessed for the participants in both groups.

RESULTS

Thirty-eight trainees participated (19 in each group). The median scores obtained for the first, second, and third tests were 38 (24,55), 80 (70,86), and 75 (70,81) points, respectively. In the second test, trainees in the variable group had a mean score 6.8 points higher than those in the control group (p = 0.103); in the last test, the mean score was 9.7 points higher in the variable group than in the control group (p = 0.003).

CONCLUSIONS

It is convenient to use hands to create a model representing the ventricular outflow tract. Trainees using this model had a better understanding and retention of the ventricular outflow tract anatomy compared to those of the control group.

Low voltage area guided substrate modification in nonparoxysmal atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Low voltage areas (LVAs) on left atrial (LA) bipolar voltage mapping correlate with areas of fibrosis. LVAs guided substrate modification was hypothesized to improve the success rate of atrial fibrillation (AF) ablation particularly in nonparoxysmal AF population. However, randomized controlled trials (RCTs) and observational studies yielded mixed results.

METHODS

The databases of Pubmed, EMBASE and Cochrane Central databases were searched from inception to August 2022. Relevant studies comparing LVA guided substrate modification (LVA ablation) versus conventional AF ablation (non LVA ablation) in patients with nonparoxysmal AF were identified and a meta-analysis was performed (Graphical Abstract image). The efficacy endpoints of interest were recurrence of AF and the need for repeat ablation at 1-year. The safety endpoint of interest was adverse events for both groups. Procedure related endpoints included total procedure time and fluoroscopy time.

RESULTS

A total of 11 studies with 1597 patients were included. A significant reduction in AF recurrence at 1-year was observed in LVA ablation versus non LVA ablation group (risk ratio [RR] 0.63 (27% vs. 36%),95% confidence interval [CI] 0.48-0.62, p < .001]. Also, redo ablation was significantly lower in LVA ablation group (RR 0.52[18% vs. 26.7%], 95% CI 0.38-0.69, p < .00133). No difference was found in the overall adverse event (RR 0.7 [4.3% vs. 5.4%], 95% CI 0.36-1.35, p = .29).

CONCLUSION

LVA guided substrate modification provides significant reduction in recurrence of all atrial arrhythmias at 1-year compared with non LVA approaches in persistent and longstanding persistent AF population without increase in adverse events.

Atrial electrogram amplitude variability during atrial fibrillation ablation

INTRODUCTION

Variability of the bipolar atrial electrogram amplitude may affect voltage maps created during ablation procedures, and thus also the extent of ablations. Therefore, the aim of the study was to assess the beat-to-beat electrogram amplitude variability in the left atrium in patients undergoing atrial fibrillation ablation.

METHODS

In 11 patients undergoing ablation for atrial fibrillation, 362 mapping points were collected in two series. At each point, three consecutive beats were recorded and verified including the bipolar electrogram amplitude, contact force (CF), and orientation of the catheter tip. The repeatability and reproducibility of obtained measurements between consecutive beats and series were assessed by the Pearson correlation coefficient (r), the Bland-Altman test, repeatability coefficient (RC), relative standard deviation (RSD), and concordance correlation coefficient (CCC).

RESULTS

A total of 1086 beats were analyzed. The correlation coefficient for bipolar atrial electrogram amplitude for the first two beats, and for the first and the third beats were 0.94 and 0.86, respectively. The average of differences between the first two beats and between the first and the third beats were 0.06 and 0.13 mV with 95% limits of agreement (LoA) within ±0.98 and ±1.74 mV, respectively. For CF values ≤5 and ≥20 g, the 95% LoA were narrower compared to other CF ranges and were ±0.49 and ±0.71 mV from the average value, respectively. When the analyzes were performed within the predefined ranges of bipolar electrogram amplitude: 0.05-1; 1-2; 2-3 mV, the 95% LoA were within ±0.33, ±0.98, and ±0.84 mV from the average value, respectively. RC and RSD were 1.41 mV and 20.8%, respectively. For repeated measurement between series, CCC ranged from 0.67 to 0.71 and the 95% LoA were within ±2.7 to 2.9 mV from the average value.

CONCLUSION

Bipolar atrial electrogram amplitude recorded at a given site during ablation procedures is variable to an extent that may be clinically relevant. The magnitude of the observed variability is greater during remapping.

Empirical superior vena cava isolation improves outcomes of radiofrequency re-ablation in pulmonary vein isolation non-responders: A 2-center retrospective study in China

Background

Pulmonary vein isolation (PVI) is the standard ablation strategy for treating atrial fibrillation (AF). However, the optimal strategy of a repeat procedure for PVI non-responders remains unclear.

Objective

This study aims to investigate the incidence of PVI non-responders in patients undergoing a repeat procedure, as well as the predictors for the recurrence of repeat ablation.

Methods

A total of 276 consecutive patients who underwent repeat ablation from August 2016 to July 2019 in two centers were screened. A total of 64 (22%) patients with durable PVI were enrolled. Techniques such as low voltage zone modification, linear ablation, non-PV trigger ablation, and empirical superior vena cava (SVC) isolation were conducted.

Results

After the 20.0 ± 9.9 month follow-up, 42 (65.6%) patients were free from atrial arrhythmias. A significant difference was reported between the recurrent and non-recurrent groups in non-paroxysmal AF (50 vs. 23.8%, p = 0.038), diabetes mellitus (27.3 vs. 4.8%, p = 0.02), and empirical superior vena cava (SVC) isolation (28.6 vs. 60.5%, p = 0.019). Multivariate regression analysis demonstrated that empirical SVC isolation was an independent predictor of freedom from recurrence (95% CI: 1.64-32.8, p = 0.009). Kaplan-Meier curve demonstrates significant difference in recurrence between empirical and non-empirical SVC isolation groups (HR: 0.338; 95% CI: 0.131-0.873; p = 0.025).

Conclusion

About 22% of patients in repeat procedures were PVI non-responders. Non-paroxysmal AF and diabetes mellitus were associated with recurrence post-re-ablation. Empirical SVC isolation could potentially improve the outcome of repeat procedures in PVI non-responders.

Omnipolar Versus Bipolar Electrode Mapping in Patients With Atrial Fibrillation Undergoing Catheter Ablation

BACKGROUND

Peak-to-peak bipolar voltage varies with electrode orientation, fractionation, and collision events. Novel, omnipolar mapping is less dependent on electrode orientation but has limited data in humans.

OBJECTIVES

This study sought to compare bipolar peak-to-peak voltage with omnipolar maximum voltage (Vmax) during sinus rhythm in the left atrium of patients with persistent (PerAF) or paroxysmal atrial fibrillation (PAF).

METHODS

Baseline voltage maps were generated with bipolar and omnipolar mapping in 20 patients undergoing de novo catheter ablation for PerAF or PAF and 9 patients with known scar from prior cardiac surgery, to validate voltage-based scar approximations. Low voltage was defined as <0.5 mV and scar <0.1 mV. Mean voltage was compared with unpaired t testing. Percent low voltage and scar were compared with chi-square testing. A point-to-point comparison was performed with Bland-Altman analysis.

RESULTS

The mean age was 62.2 ± 9.9 years, 34% were women, and 41% had heart failure. Omnipolar mapping identified significantly higher mean voltage than bipolar mapping and classified less points as low voltage (PerAF: 32.90% vs 43.40%; PAF: 19.20% vs 25.60%) and scar (PerAF: 7.72% vs 12.10%; PAF: 4.03% vs 6.07%) (all P < 0.0001). Omnipolar Vmax displayed significant disagreement with bipolar by Bland-Altman analysis. Scar and low-voltage approximations were validated in atria with known scar, in which bipolar mapping overestimated the extent of low voltage (P < 0.0001) and scar (P < 0.0001).

CONCLUSIONS

Omnipolar mapping identifies higher voltage and has greater specificity for the detection of low voltage and scar than conventional bipolar mapping in patients with PerAF or PAF.

Characterization of arrhythmia substrate to ablate persistent atrial fibrillation (COAST-AF): Randomized controlled trial design and rationale

BACKGROUND

Atrial low voltage area (LVA) catheter ablation has emerged as a promising strategy for ablation of persistent atrial fibrillation (AF). It is unclear if catheter ablation of atrial LVA increases treatment success rates in patients with persistent AF.

OBJECTIVE

The primary aim of this trial is to assess the potential benefit of adjunctive catheter ablation of atrial LVA in addition to pulmonary vein isolation (PVI) in patients with persistent AF, when compared to PVI alone. The secondary aims are to evaluate safety outcomes, the quality of life and the healthcare resource utilization.

METHODS/DESIGN

A multicenter, prospective, parallel-group, 2-arm, single-blinded randomized controlled trial is under way (NCT03347227). Patients who are candidates for catheter ablation for persistent AF will be randomly assigned (1:1) to either PVI alone or PVI + atrial LVA ablation. The primary outcome is 18-month documented event rate of atrial arrhythmia (AF, atrial tachycardia or atrial flutter) post catheter ablation. Secondary outcomes include procedure-related complications, freedom from atrial arrhythmia at 12 months, AF burden, need for emergency department visits/hospitalization, need for repeat ablation for atrial arrhythmia, quality of life at 12 and 18 months, ablation time, and procedure duration.

DISCUSSION

Characterization of Arrhythmia Mechanism to Ablate Atrial Fibrillation (COAST-AF) is a multicenter randomized trial evaluating ablation strategies for catheter ablation. We hypothesize that catheter ablation of atrial LVA in addition to PVI will result in higher procedural success rates when compared to PVI alone in patients with persistent AF.

Efficacy of left atrial low-voltage area-guided catheter ablation of atrial fibrillation: An updated systematic review and meta-analysis

AIMS

This study aimed to evaluate the efficacy of low-voltage area (LVA)-guided substrate modification catheter ablation in patients with atrial fibrillation (AF).

METHODS

Systematic searches of the PubMed, EMBASE, and Cochrane databases were performed from inception to July 2022 for all available studies. The effect estimates were combined with the Mantel-Haenszel random-effects model. Subgroup analyses, sensitivity analysis, and meta-regression were conducted to explore the sources of statistical heterogeneity.

RESULTS

A total of 16 studies involving 1942 subjects (mean age: 61 ± 10 years, 69% male) were identified. All studies included patients with paroxysmal AF, non-paroxysmal AF, or both. At a mean follow-up of 18.9 months, patients who underwent LVA-guided substrate modification ablation had significantly higher freedom from all-atrial tachycardia recurrence than patients who underwent control ablation [67.7% vs. 48.9%, risk ratios (RR) 0.64, 95% confidence interval (CI) 0.55-0.76, P < 0.001], with 36% relative risk and 18.7% absolute risk reductions in all-atrial tachycardia recurrence. Subgroup analysis based on AF types demonstrated that the decreased risk of all-atrial tachycardia recurrence was present predominantly in non-paroxysmal AF compared with paroxysmal AF (RR 0.60, 95% CI 0.52-0.69 vs. RR 0.96, 95% CI 0.81-1.13).

CONCLUSION

Low-voltage area-guided substrate modification ablation combined with PVI appears to have a significant beneficial effect of improving freedom from all-atrial tachycardia recurrence, especially in patients with non-paroxysmal AF.

Catheter ablation and thoracoscopic ablation in long persistent atrial fibrillation with large left atrium

Background

Pulmonary vein antrum isolation (PVAI) is the cornerstone of atrial fibrillation (AF) ablation, but the clinical outcomes of PVAI are unsatisfactory in patients with persistent AF and a large left atrium (LA).

Objectives

We investigated the clinical outcomes following radiofrequency ablation (RFCA), cryoballoon ablation (CBA), and thoracoscopic maze in patients with persistent AF and a large LA.

Methods

We included patients with consecutive persistent AF who had a large LA (LA diameter >50 mm) and underwent RFCA, CBA, or thoracoscopic maze surgery. In the RFCA group, additional linear ablation was performed at the physician’s discretion. The endpoint was 12 months without recurrence of an atrial arrhythmia, including AF, atrial flutter, and atrial tachycardia, following a 90-day blanking period.

Results

We recruited 89 persistent AF patients with a large LA who underwent RFCA (n = 32), CBA (n = 38), or the thoracoscopic maze procedure (n = 19). During the 12-month follow-up, 48 (53.9%) cases of AF recurrence were observed. There was no prognostic difference between groups (50.0% in RFCA vs. 52.6% in CBA vs. 63.2% in thoracoscopic maze, all P > 0.05). Early recurrence during the blanking period was a significant predictor of late recurrence for RFCA and CBA, but not for the thoracoscopic maze.

Conclusion

In persistent AF patients with a large LA, we did not find a prognostic difference RFCA, CBA, or a thoracoscopic maze procedure in recurrence of atrial arrhythmia. Early recurrence predicted late recurrence in catheter ablation, but not in thoracoscopic maze.

A systematic review and meta-analysis of the safety and efficacy of left atrial substrate modification in atrial fibrillation patients with low voltage areas

Background

The left atrial low-voltage areas (LVAs) are associated with atrial fibrosis; however, it is not clear how the left atrial LVAs affect the recurrence of arrhythmias after catheter ablation, and the efficacy and safety of the left atrial substrate modification based on LVAs as a strategy for catheter ablation of atrial fibrillation (AF) are not evident for AF patients with LVAs.

Methods

We performed a systematic search to compare the arrhythmia recurrence in AF patients with and without LVAs after conventional ablation and arrhythmia recurrence in LVAs patients after conventional ablation with and without substrate modification based on LVAs.

Result

A total of 6 studies were included, involving 1,175 patients. The arrhythmia recurrence was higher in LVA patients after conventional ablation (OR: 5.14, 95% CI: [3.11, 8.49]; P < 0.00001). Additional LVAs substrate modification could improve the freedom of arrhythmia in LVAs patients after the first procedure (OR: 0.30, 95% CI: [0.15, 0.62]; P = 0.0009). However, there was no significant difference after multiple procedures (P = 0.19). The procedure time (MD: 26.61, 95% CI [15.79, 37.42]; P < 0.00001) and fluoroscopy time (MD: 6.90, 95% CI [4.34, 9.47]; P < 0.00001) in LVAs patients with additional LVAs substrate modification were significantly increased compared to LVAs patients' without substrate modification. Nevertheless, there were no higher LVAs substrate modification-related complications (P = 0.93) between LVAs patients with and without additional LVAs substrate modification. In the subgroup analysis, the additional LVAs substrate modification reduced the risk of arrhythmia recurrence in LVAs patients during the follow-up time, which was 12 months (OR: 0.32, 95% CI (0.17, 0.58); P = 0.002), and box isolation (OR: 0.37, 95% CI (0.20, 0.69); P = 0.002) subgroups, but the type of AF, follow up >12 months and homogenization subgroups were not statistically significant. Trial sequential analysis shows conclusive evidence for the LVAs ablation.

Conclusion

This study has shown that LVAs could improve the risk of arrhythmia recurrence in AF patients after conventional ablation. And additional LVAs substrate modification after conventional ablation could increase the freedom of arrhythmia recurrence in LVAs patients. Interestingly, the box isolation approach appeared more promising.

Systematic review registration

[http://www.crd.york.ac.uk/prospero], identifier [CRD42021239277].

Comparative efficacy and safety of different catheter ablation strategies for persistent atrial fibrillation: a network meta-analysis of randomized clinical trials

AIMS

Whereas pulmonary vein isolation (PVI) is the universally agreed target in catheter ablation of paroxysmal atrial fibrillation (AF), an ideal ablation set in persistent AF remains questioned. Aim of this study is to conduct a network meta-analysis (NMA) of randomized clinical trials (RCTs) comparing different ablation strategies in persistent AF patients.

METHODS AND RESULTS

Network meta-analysis was performed in a frequentist framework with the different ablation strategies constituting the competitive arms of interest. Primary efficacy endpoint was recurrences of atrial tachyarrhythmia (AF, atrial flutter, and/or organized atrial tachycardia). Secondary endpoints included major peri-procedural complications, procedure, and fluoroscopy duration. PubMED/MEDLINE and EMBASE databases were searched through June 2020. 2548 records were screened and 57 full-text articles assessed. Eventually 24 RCTs were included, encompassing 3245 patients (median follow-up 15 months, IQR 12-18). Compared to PVI alone, PVI plus linear lesions in the left atrium and elimination of extra-PV sources was the only strategy associated with a reduced risk of arrhythmia recurrence (RR 0.49, 95%CI 0.27-0.88). Most treatment arms were associated with longer procedural time compared with PVI; however, major peri-procedural complications and fluoroscopy time did not differ.

CONCLUSION

A comprehensive strategy including PVI, linear lesions in the left atrium, and elimination of extra-PV sources (constrained by a heterogeneous definition across studies) was associated with reduced risk of recurrent atrial tachyarrhythmias compared to PVI alone. All investigated treatment arms yielded similar safety profiles. Further research should rely on enhanced substrate-based approach definitions to solve one of the most evident knowledge gaps in interventional electrophysiology.