Influence of underlying substrate on atrial tachyarrhythmias after pulmonary vein isolation

Left atrial remodeling and voltage-guided ablation outcome in obese patients with persistent atrial fibrillation

Background

Obesity is a risk factor for atrial fibrillation (AF). Data regarding left atrial (LA) remodeling in obese patients are scarce. Whether obesity favors AF recurrence after catheter ablation (CA) is still controversial. We assessed the distribution of epicardial atrial fat on computed tomography (CT), LA bipolar voltage, low-voltage zone (LVZ) extent, and the outcome of voltage-guided ablation of persistent AF in obese and non-obese patients.

Methods

A total of 139 patients with persistent AF undergoing a first voltage-guided ablation were enrolled and divided into two groups: 74 were non-obese and 65 were obese. Epicardial adipose tissue (EAT) was assessed on a CT scanner. LA endocardial voltage maps were obtained using a 3D mapping system in sinus rhythm. LVZ was defined as a bipolar peak-to-peak voltage amplitude <0.5 mV.

Results

LA volume, voltage, and EAT amount were similar in the two groups. LVZ was less frequent in obese patients [12 (18.8%) vs. 26 (35.1%), p = 0.05], particularly on the anterior wall. The posterior and lateral EATs were correlated with posterior and lateral LVZ extent, respectively, in obese patients. After 36 months of follow-up, the AF-free survival rate was similar. Lateral EAT [odds ratio (OR) 1.21, 95% confidence interval (CI) 1-1.4, p = 0.04] and P-wave duration (OR 1.03, 95% CI 1-1.05, p = 0.03), but not body mass index (BMI), were predictors of AF recurrence after CA.

Conclusion

In obese patients, LVZ was less marked than in non-obese patients with similar LA volumes, voltage, and EAT amounts. In obese patients, posterior and lateral EATs were correlated with posterior and lateral LVZ extents. Obese patients had a similar and favorable 36-month outcome after AF ablation. BMI was not predictive of AF recurrence.

The omnipolar mapping technology-a new mapping tool to overcome "bipolar blindness" resulting in true high-density maps

BACKGROUND

Omnipolar mapping (OT) is a novel tool to acquire omnipolar signals for electro-anatomical mapping, displaying true voltage and real-time wavefront direction and speed independent of catheter orientation. The aim was to analyze previously performed left atrial (LA) and left ventricular (LV) maps for differences using automated OT vs. standard bipolar settings (SD) and HD wave (HDW) algorithm.

METHODS

Previously obtained SD and HDW maps of the LA and LV using a 16-electrode, grid-shaped catheter were retrospectively analyzed by applying automated OT, comparing voltage, point density, pulmonary vein (PV) gaps, and LV scar area.

RESULTS

In this analysis, 135 maps of 45 consecutive patients (30 treated for LA, 15 for LV arrhythmia) were included. Atrial maps revealed significantly higher point densities using OT (21471) vs. SD (6682) or HDW (12189, p < 0.001). Mean voltage was significantly higher using OT (0.75 mV) vs. SD (0.61 mV) or HDW (0.64 mV, p < 0.001). OT maps detected significantly more PV gaps per patient vs. SD (4 vs. 2), p = 0.001. In LV maps, OT revealed significantly higher point densities (25951) vs. SD (8582) and HDW (17071), p < 0.001. Mean voltage was significantly higher for OT (1.49 mV) vs. SD (1.19 mV) and HDW (1.2 mV), p < 0.001. Detected scar area was significantly smaller using OT (25.3%) vs. SD (33.9%, p < 0.001).

CONCLUSION

OT mapping leads to significantly different substrate display, map density, voltage, detection of PV gaps, and scar size, compared to SD and HDW in LA and LV procedures. Successful CA might be facilitated due to true HD maps.

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.

Conduction time around the mitral valve annulus has the potential to rule out postablation perimitral atrial tachycardia

INTRODUCTION

It would be helpful in determining ablation strategy if the occurrence of perimitral atrial tachycardia (PMAT) could be predicted in advance. We investigated whether estimated perimitral conduction time (E-PMCT), namely, twice the time between coronary sinus (CS) pacing and the ensuing wave-front collision at the opposite side of the mitral annulus, correlated with the cycle length of PMAT and could predict future PMAT.

METHODS AND RESULTS

We retrospectively (retrospective cohort) and prospectively (validation cohort) investigated atrial fibrillation patients who had received pulmonary vein isolation (PVI) and in whom left atrial maps had been created during CS pacing. We calculated their E-PMCT. PMAT was observed either by provocation or during follow-up in 25, AT other than PMAT was observed in 24 (non-PMAT AT group), and 53 patients never displayed any AT (no-AT group) in the retrospective cohort. In the PMAT group of the retrospective cohort, a strong positive correlation was observed between the PMAT CL and E-PMCT (r = .85, p < 0.001). PMAT was never induced nor observed in patients with E-PMCT less than 176 ms, and the best cut-off value for PMAT was 180 ms by receiver-operating characteristic curve analysis. In the validation cohort of 76 patients, the cut-off value of the E-PMAT less than 180 ms predicted noninducibility of PMAT, with a sensitivity of 78.6%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 25.0%.

CONCLUSION

Short E-PMCT may predict noninducibility of PMAT and guide a less invasive ablation strategy.

Long-Term Impact of Additional Ablation After Pulmonary Vein Isolation: Results From EARNEST-PVI Trial

Background An optimal strategy for left atrial ablation in addition to pulmonary vein isolation (PVI) in patients with persistent atrial fibrillation (AF) has not been determined. Methods and Results We conducted an extended follow-up of the multicenter randomized controlled EARNEST-PVI (Efficacy of Pulmonary Vein Isolation Alone in Patients With Persistent Atrial Fibrillation) trial, which compared 12-month rhythm outcomes in patients with persistent AF between patients randomized to a PVI-alone strategy (n=248) or PVI-plus strategy (n=248; PVI followed by left atrial additional ablation, including linear ablation or ablation targeting areas with complex fractionated electrograms). The present study extended the follow-up period to 3 years after enrollment. Outcomes were compared not only between randomly allocated groups but also between on-treatment groups categorized by actually created ablation lesions. Recurrence rate of AF or atrial tachycardia (AT) was lower in the randomly allocated to PVI-plus group than the PVI-alone group (29.0% versus 37.5%, P=0.036). On-treatment analysis revealed that patients with PVI+linear ablation (n=205) demonstrated a lower AF/AT recurrence rate than those with PVI only (26.3% versus 37.8%, P=0.007). In contrast, patients with PVI+complex fractionated electrograms ablation (n=37) had an AF/AT recurrence rate comparable to that of patients with PVI only (40.5% versus 37.8%, P=0.76). At second ablation in 126 patients with AF/AT recurrence, ATs excluding common atrial flutter were more frequent in patients with PVI+linear ablation than in those with PVI only (32.6% versus 5.7%, P<0.0001). Conclusions Left atrial ablation in addition to PVI was efficacious during 3-year follow-up. Linear ablation was superior to other ablation strategies but may increase iatrogenic ATs. Registration URL: http://www.umin.ac.jp/ctr/index-j.htm; Unique identifier: UMIN000019449.

Personalized pulmonary vein antrum isolation guided by left atrial wall thickness for persistent atrial fibrillation

AIMS

Pulmonary vein (PV) antrum isolation proved to be effective for treating persistent atrial fibrillation (PeAF). We sought to investigate the results of a personalized approach aimed at adapting the ablation index (AI) to the local left atrial wall thickness (LAWT) in a cohort of consecutive patients with PeAF.

METHODS AND RESULTS

Consecutive patients referred for PeAF first ablation were prospectively enrolled. The LAWT three-dimensional maps were obtained from pre-procedure multidetector computed tomography and integrated into the navigation system. Ablation index was titrated according to the local LAWT, and the ablation line was personalized to avoid the thickest regions while encircling the PV antrum. A total of 121 patients (69.4% male, age 64.5 ± 9.5 years) were included. Procedure time was 57 min (IQR 50-67), fluoroscopy time was 43 s (IQR 20-71), and radiofrequency (RF) time was 16.5 min (IQR 14.3-18.4). The median AI tailored to the local LAWT was 387 (IQR 360-410) for the anterior wall and 335 (IQR 300-375) for the posterior wall. First-pass PV antrum isolation was obtained in 103 (85%) of the right PVs and 103 (85%) of the left PVs. Median LAWT values were higher for PVs without first-pass isolation as compared to the whole cohort (P = 0.02 for left PVs and P = 0.03 for right PVs). Recurrence-free survival was 79% at 12 month follow-up.

CONCLUSION

In this prospective study, LAWT-guided PV antrum isolation for PeAF was effective and efficient, requiring low procedure, fluoroscopy, and RF time. A randomized trial comparing the LAWT-guided ablation with the standard of practice is in progress (ClinicalTrials.gov, NCT05396534).

Electrogram Morphology Recurrence for Mapping Persistent Atrial Fibrillation: Initial vs Redo Catheter Ablation

BACKGROUND

Electrogram (EGM) morphology recurrence (EMR) mapping of persistent atrial fibrillation (AF) quantifies consistency of activation and is expected to be high and rapid near AF drivers.

OBJECTIVES

The purpose of this study was to compare EMR in left atria (LA) and right atria (RA) in patients undergoing first vs redo ablation for persistent AF.

METHODS

Multisite LA/RA mapping (LA: 281 ± 176 sites/patient; RA: 239 ± 166 sites/patient) before persistent AF ablation was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (Group 1, n = 32) or redo ablation (Group 2, n = 10). After cross-correlation of each automatically detected EGM with every other EGM per recording, the most recurrent electrogram morphology was identified and its frequency (Rec%) and recurrence cycle length (CLR) were computed.

RESULTS

In Groups 1 and 2, minimum CLR was 172.8 ± 26.0 milliseconds (LA: 178.2 ± 37.6 milliseconds, RA: 204.4 ± 34.0 milliseconds, P = 0.0005) and 186.5 ± 28.3 milliseconds (LA: 196.1 ± 38.1 milliseconds vs RA: 199.0 ± 30.2 milliseconds, P = 0.75), with Rec% 94.7% ± 10% and 93.8% ± 9.2%. Group 2 minimum CLR was not different from Group 1 (P = 0.20). Shortest CLR was in the LA in 84% of Group 1 and 50% of Group 2 patients (P = 0.04). Only 1 of 10 patients in Group 2 had the shortest CLR in the pulmonary veins (PVs) compared with 19 of 32 in Group 1 (P = 0.01). Most sites (77.6%) had Rec% <50%.

CONCLUSIONS

EMR identified the shortest CLR sites in the PVs in 59% of patients undergoing initial persistent AF ablation, consistent with reported success rates of ∼50% for PV isolation. The majority of sites have low recurrence and may reflect bystander sites not critical for maintaining AF. EMR provides a robust new method for quantifying consistency and rapidity of activation direction at multiple atrial sites.

Abnormal Conduction Zone Detected by Isochronal Late Activation Mapping Accurately Identifies the Potential Atrial Substrate and Predicts the Atrial Fibrillation Ablation Outcome After Pulmonary Vein Isolation

BACKGROUND

The presence of abnormal substrate of left atrium is a predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation. We aimed to investigate the isochronal late activation mapping to access the abnormal conduction velocity for predicting AF ablation outcome.

METHODS

Forty-five paroxysmal AF patients (30 males, 57.8±8.7 years old) who underwent pulmonary vein isolation were enrolled. Isochronal late activation mapping was retrospectively constructed with 2 different windows of interest: from onset of P wave to onset of QRS wave on surface electrocardiography (W1) and 74 ms tracking back from the end of P wave (W2). Deceleration zone was defined as regions with 3 isochrones (DZa) or ≥4 isochrones (DZb) within a 1 cm radius on the isochronal late activation mapping, and the estimated conduction velocity (ECV) are 0.27 m/s and <0.20 m/s for DZa and DZb, respectively in W2. The distribution of deceleration zone was compared with the location of low-voltage zone (bipolar voltage ≤0.5 mV). Any recurrence of atrial arrhythmias was defined as the primary end point during follow ups after a 3-month blanking period.

RESULTS

Pulmonary vein isolation was performed in all patients, and there were 2 patients (4.4%) received additional extrapulmonary vein ablation. After a mean follow-up of 12.7±4.5 months, recurrence of AF occurred in 14 patients (31.1%). Patients with the presence of DZb in W2 had higher AF recurrence (Kaplan-Meier event rate estimates: HR, 9.41 [95% CI, 2.61-33.90]; log-rank P<0.0001). There were 52.6% of the DZb locations in W2 comparable to the distributions of low-voltage zone and 47.4% DZb were distributed in the area without low-voltage zone.

CONCLUSIONS

Deceleration zone detected by isochronal late activation mapping represents a critical AF substrate, it accurately predicts the AF recurrence following ablation in patients with paroxysmal 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 &lt; 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.

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].

Electrical Remodeling of Left Atrium Is a Better Predictor for Recurrence Than Structural Remodeling in Atrial Fibrillation Patients Undergoing Radiofrequency Catheter Ablation

We demonstrated that the electrical remodeling represented by low voltage zone is a better marker for the prediction of recurrence after radiofrequency catheter ablation as compared with structural remodeling measured by left atrium (LA) diameter. The study provides important clue that further deep dive into LA substrate research will be important to improve success rate of non-paroxysmal atrial fibrillation ablation.

Background and Objectives

Recurrence rates after radiofrequency catheter ablation (RFCA) in atrial fibrillation (AF) patients are not low especially in non-paroxysmal AF. The diameter of left atrium (LA) has been widely used to predict the recurrence after RFCA for decades. However, LA diameter represents structural remodeling of LA and does not reflect electrical remodeling. We aimed to determine the predictive value of electrical remodeling of LA which is represented by the amount of low voltage zone (LVZ).

Methods

We performed a retrospective cohort analysis of AF patients who underwent de novo RFCA in a single-center.

Results

A total of 3,120 AF patients with de novo RFCA were analyzed. Among these patients, 537 patients underwent an electroanatomic mapping with bipolar voltage measurement of LA. The diameter of LA and flow velocity of LA appendage (LAA) differed significantly according to quartile group of LVZ area and percentage: patients with high LVZ had large LA diameter and low LAA flow velocity (p<0.001). Freedom from late recurrence (LR) was significantly lower in patients with high LVZ area and percentage (p<0.001). The diameter and surface area of LA had area under curve (AUC) of 0.592 and 0.593, respectively (p=0.002 for both). The predictive value of LVZ area (AUC, 0.676) and percentage (AUC, 0.671) were both superior compared with LA diameter (p=0.011 and 0.027 for each comparison).

Conclusions

In conclusion, LVZ can predict freedom from LR after RFCA in AF patients. Predictive value was higher in parameters reflecting electrical rather than structural remodeling of LA.

Extensive Left Atrial Low-Voltage Area During Initial Ablation is Associated with A Poor Clinical Outcome Even Following Multiple Procedures

Background

Some patients fail to respond to persistent atrial fibrillation (PeAF) catheter ablation in spite of multiple procedures and ablation strategies, including low voltage area (LVA)-guided, linear, and complex fractionated atrial electrogram (CFAE)-guided ablation procedures. We hypothesized that LVA extent could predict non-responseto Pe AF catheter ablation in spite of multiple procedures.

Methods

This study included 510 patients undergoing initial ablation procedures for PeAF. LVAs were defined as regions with bipolar peak-to-peak voltages of <0.50 mV after PVI during sinus rhythm. Patients were categorized by LVA size into groups A(0-5 cm²), B (5-20 cm²), and C (over 20 cm²). The primary endpoint was AF-free survival after the last procedure.

Results

During a median follow-up of 25 (17, 36) months, AF recurrence was observed in 101 (20%) patients after 1.4±0.6 ablation procedures (maximum 4). Comparison of clinical outcomes after multiple procedures in the three groups showed that the results depended on the extent of LVA. Multivariate analysis of AF-free survival after the last procedure showed that LVAs > 20 cm2 was an independent factor associated with AF recurrence after the final procedure(Hazard ratio, 7.94; 95% confidence interval, 2.91 to 21.67, P <0.001).

Conclusions

Extensive LVA after initial PVI was associated with poor clinical benefit despite multiple catheter based ablations.

Low voltage zones detected by omnipolar Vmax map accurately identifies the potential atrial substrate and predicts the AF ablation outcome after PV isolation

INTRODUCTION

The presence of bipolar low-voltage zone (LVZ) is a predictor of AF recurrence after PV isolation (PVI). However, changes of wavefront and bipole directions may cause different electrogram characteristics. We aimed to investigate whether using omnipolar maximum voltage (Vmax) map derived from high density (HD) Grid mapping catheter could assess LVZ and AF ablation outcome accurately.

METHODS

Fifty paroxysmal AF patients (27 males, 57.8 ± 9.5 years old) who underwent 3D mapping guided PVI were enrolled. Left atrial voltage mapping during sinus rhythm before ablation was performed. The significant LVZ (<0.5 mV with area > 5 cm²) were defined as sites by omnipolar Vmax, bipolar HD wave map, conventional bipolar electrograms acquired from electrode pairs along to and across to the catheter shaft. The primary end point was the first documented recurrence of any AF during follow-ups.

RESULTS

PVI was performed in all patients, and there were 2 patients (4%) who also received additional non-PV triggers ablation. After a follow-up of 11.4 ± 5.4 months, recurrence of AF occurred in 12 patients (24%). The presence of a significant LVZ was less detected by omnipolar Vmax map, compared to HD wave map (24.0% vs. 58.0%, p = 0.001). LVZ detected by omnipolar Vmax map independently predicted the AF recurrence (odds ratio 16.91; 95% CI, 3.17-90.10; p = 0.001).

CONCLUSION

LVZ detected by omnipolar Vmax map accurately predicts the AF recurrence following ablation in paroxysmal AF, compared to conventional bipolar and HD wave maps, suggesting the omnipolar Vmax map can precisely define the atrial substrate property.

Deep Learning-Based Recurrence Prediction of Atrial Fibrillation After Catheter Ablation

BACKGROUND

Radiofrequency catheter ablation (RFCA) is an effective therapy for atrial fibrillation (AF). However, it the problem of AF recurrence remains. This study investigates whether a deep convolutional neural network (CNN) can accurately predict AF recurrence in patients with AF who underwent RFCA, and compares CNN with conventional statistical analysis.Methods and Results:Three-hundred and ten patients with AF after RFCA treatment, including 94 patients with AF recurrence, were enrolled. Nine variables are identified as candidate predictors by univariate Cox proportional hazards regression (CPH). A CNNSurv model for AF recurrence prediction was proposed. The model's discrimination ability is validated by a 10-fold cross validation method and measured by C-index. After back elimination, 4 predictors are used for model development, they are N-terminal pro-BNP (NT-proBNP), paroxysmal AF (PAF), left atrial appendage volume (LAAV) and left atrial volume (LAV). The average testing C-index is 0.76 (0.72-0.79). The corresponding calibration plot appears to fit well to a diagonal, and the P value of the Hosmer-Lemeshow test also indicates the proposed model has good calibration ability. The proposed model has superior performance compared with the DeepSurv and multivariate CPH. The result of risk stratification indicates that patients with non-PAF, higher NT-proBNP, larger LAAV and LAV would have higher risks of AF recurrence.

CONCLUSIONS

The proposed CNNSurv model has better performance than conventional statistical analysis, which may provide valuable guidance for clinical practice.

Low-Voltage Zones as the Atrial Fibrillation Substrates: Relationship With Initiation, Perpetuation, and Termination

Background: Low-voltage zones (LVZs) were usually targeted for ablation in atrial fibrillation (AF). However, its relationship with AF initiation, perpetuation, and termination remains to be studied. This study aimed to explore such relationships.

Methods: A total of 126 consecutive AF patients were enrolled, including 71 patients for AF induction protocol and 55 patients for AF termination protocol. Inducible and sustainable AF were defined as induced AF lasting over 30 and 300 s, respectively. Terminable AF was defined as those that could be terminated into sinus rhythm within 1 h after ibutilide administration. Voltage mapping was performed in sinus rhythm for all patients. LVZ was quantified as the percentage of the LVZ area (LVZ%) to the left atrium surface area.

Results: The rates of inducible, sustainable, and terminable AF were 29.6, 18.3, and 38.2%, respectively. Inducible AF patients had no significant difference in overall LVZ% compared with uninducible AF patients (10.2 ± 11.8 vs. 8.5 ± 12.6, p = 0.606), while sustainable and interminable AF patients had larger overall LVZ% than unsustainable (16.2 ± 11.5 vs. 0.5 ± 0.7, p < 0.001) and terminable AF patients (44.6 ± 26.4 vs. 26.3 ± 22.3, p < 0.05), respectively. The segmental LVZ distribution pattern was diverse in the different stages of AF. Segmental LVZ% difference was initially observed in the anterior wall for patients with inducible AF, and the septum was further affected in those with sustainable AF, and the roof, posterior wall, and floor were finally affected in those with interminable AF.

Conclusions: The associations between LVZ with AF initiation, perpetuation, and termination were different depending on its size and distribution.

Low-Voltage-Area Ablation in Paroxysmal Atrial Fibrillation - Extended Follow-up Results of the VOLCANO Trial

BACKGROUND

The randomized controlled VOLCANO trial demonstrated comparable 1-year rhythm outcomes between patients with and without ablation targeting low-voltage areas (LVAs) in addition to pulmonary vein isolation among paroxysmal atrial fibrillation (PAF) patients with LVAsMethods and Results:An extended-follow-up study of 402 patients enrolled in the VOLCANO trial with PAF, divided into 4 groups based on the results of voltage mapping: group A, no LVA (n=336); group B, LVA ablation (n=30); group C, LVA without ablation (n=32); and group D, incomplete voltage map (n=4). At 25 (23, 31) months after the initial ablation, AF/atrial tachycardia (AT) recurrence rates were 19% in group A, 57% in group B, 59% in group C, and 100% in group D. Recurrence rates were higher in patients with LVAs than in those without (group A vs. B+C, P<0.0001), and were comparable between those with and without LVA ablation (group B vs. C, P=0.83). Among patients who underwent repeat ablation, ATs were more frequently observed in patients with LVAs (Group B+C, 50% vs. A, 14%, P<0.0001). In addition, LVA ablation increased the incidence of AT development (group B, 71% vs. C, 32%, P<0.0001).

CONCLUSIONS

Patients with LVAs demonstrated poor long-term rhythm outcomes irrespective of LVA ablation. ATs were frequently observed in patients with LVAs, and LVA ablation might exacerbate the occurrence of iatrogenic ATs.

The efficacy and safety of left atrial low-voltage area guided ablation for recurrence prevention compared to pulmonary vein isolation alone in patients with persistent atrial fibrillation trial: Design and rationale

Recurrence rates of atrial fibrillation (AF) after pulmonary vein isolation (PVI) are higher in patients with a left atrial low‐voltage area (LVA) than those without. However, the efficacy of LVA guided ablation is still unknown. The purpose of this study—the Efficacy and Safety of Left Atrial Low‐voltage Area Guided Ablation for Recurrence Prevention Compared to Pulmonary Vein Isolation Alone in Patients with Persistent Atrial Fibrillation trial (SUPPRESS‐AF trial)—is to elucidate whether LVA guided ablation in addition to PVI is superior to PVI alone in patients with persistent AF. The Osaka Cardiovascular Conference will conduct a multicenter, randomized, open‐label trial aiming to examine whether LVA guided ablation in addition to PVI is superior to PVI alone in patients with persistent AF and LVAs. The primary outcome is the recurrence of AF documented by scheduled or symptom‐driven electrocardiography (ECG) during the 1 year follow‐up period after the index ablation. The key secondary endpoints include all‐cause death, symptomatic stroke, bleeding events, and other complications related to the procedure. A total of 340 patients with an LVA will be enrolled and followed up to 1 year. The SUPPRESS‐AF trial is a randomized controlled trial designed to assess whether LVA guided ablation in addition to PVI is superior to PVI alone for patients with persistent AF and LVAs detected while undergoing their first catheter ablation.

Impact of right atrial structural remodeling on recurrence after ablation for atrial fibrillation

BACKGROUND

Recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) is associated with left atrial (LA) remodeling; however, its association with right atrial (RA) remodeling remains unclear.

OBJECTIVE

This study aimed to identify whether RA structural remodeling could predict recurrence of AF after PVI.

METHODS

This study prospectively analyzed 245 patients with AF who had undergone PVI. RA and LA volumes were determined by contrast-enhanced computed tomography. Atrial structural remodeling was defined as an atrial volume of ≥110 mL according to previous reports and receiver operating characteristic curve analysis.

RESULTS

After excluding 32 patients, 213 patients were analyzed. During a follow-up period of 12 months, 41 patients (19%) demonstrated atrial arrhythmia recurrence after PVI. With the Cox proportional-hazards model, RA structural remodeling was the only predictor of arrhythmia recurrence (hazard ratio, 1.012; 95% confidence interval 1.003-1.021; P = .009). Kaplan-Meier analysis showed that arrhythmia recurrence was more frequent in the RA structural remodeling group compared with the group without RA remodeling (log-rank, P < .001), and the arrhythmia-free survival rates in these groups at 12 months were 68.0% and 91.4%, respectively. Additionally, there was a significant difference in recurrence-free survival after RA structural remodeling in each type of AF (log-rank, P < .001).

CONCLUSIONS

RA structural remodeling is a useful predictor of clinical outcome after PVI regardless of the type of AF. Our results suggest that patients without RA structural remodeling may be good candidates for successful ablation with PVI.

Characterization of cardiac electrogram signals in atrial arrhythmias

Despite significant advancements in 3D cardiac mapping systems utilized in daily electrophysiology practices, the characterization of atrial substrate remains crucial for the comprehension of supraventricular arrhythmias. During mapping, intracardiac electrograms (EGM) provide specific information that the cardiac electrophysiologist is required to rapidly interpret during the course of a procedure in order to perform an effective ablation. In this review, EGM characteristics collected during sinus rhythm (SR) in patients with paroxysmal atrial fibrillation (pAF) are analyzed, focusing on amplitude, duration and fractionation. Additionally, EGMs recorded during atrial fibrillation (AF), including complex fractionated atrial EGMs (CFAE), may also provide precious information. A complete understanding of their significance remains lacking, and as such, we aimed to further explore the role of CFAE in strategies for ablation of persistent AF. Considering focal atrial tachycardias (AT), current cardiac mapping systems provide excellent tools that can guide the operator to the site of earliest activation. However, only careful analysis of the EGM, distinguishing low amplitude high frequency signals, can reliably identify the absolute best site for RF. Evaluating macro-reentrant atrial tachycardia circuits, specific EGM signatures correspond to particular electrophysiological phenomena: the careful recognition of these EGM patterns may in fact reveal the best site of ablation. In the near future, mathematical models, integrating patient-specific data, such as cardiac geometry and electrical conduction properties, may further characterize the substrate and predict future (potential) reentrant circuits.

High Brain Natriuretic Peptide Level Predicts The Prevalence Of Low-Voltage Areas And Poor Rhythm Outcome In Patients Undergoing Atrial Fibrillation Ablation

Backgrounds

The prevalence of residual left atrial low-voltage areas (LVAs) is associated with atrial fibrillation (AF) recurrence after pulmonary vein isolation. Brain natriuretic peptide (BNP) may be increased in AF patients and may raise AF recurrence risk after catheter ablation. We investigated the association between BNP and the prevalence of LVAs.

Methods

One hundred and eighty three consecutive AF cases were retrospectively enrolled that underwent initial ablation for AF (persistent AF, 82 [45%] patients). Serum BNP was measured before ablation and the natural logarithm of BNP (log-BNP) was calculated. Low-voltage points were defined as sites with left atrial electrogram amplitude <0.5 mV. LVAs were defined as regions with ≥5% low-voltage points across the total surface area of the left atrium.

Results

Of the 183 patients, 38 (21%) had LVAs. Patients with LVAs demonstrated higher log-BNP (4.8±0.9 vs. 3.9±1.2, P<0.001). The optimal cut-off value of log-BNP was 4.4, which was equivalent to 81 pg/mL of BNP. LVAs were more frequent in patients with higher log-BNP. In multivariate analysis, log-BNP >4.4 was an independent predictor of LVAs (odds ratio 2.7 [95% confidence interval 1.01-7.1], P=0.048). Freedom from AF recurrence was significantly lower in patients with than without high log-BNP (P=0.007).

Conclusions

BNP correlated with the prevalence of left atrial LVAs and AF recurrence in patients with AF undergoing catheter ablation.

A new clinical risk score for predicting the prevalence of low-voltage areas in patients undergoing atrial fibrillation ablation

INTRODUCTION

Although the presence of left atrial low-voltage areas (LVAs) is strongly associated with the recurrence of atrial fibrillation (AF) after ablation, few methods are available to classify the prevalence of LVAs. The purpose of this study was to establish a risk score for predicting the prevalence of LVAs in patients undergoing ablation for AF.

METHODS

We enrolled 1004 consecutive patients who underwent initial ablation for AF (age, 68 ± 10 years old; female, 346 (34%); persistent AF, 513 (51%)). LVAs were deemed present when the voltage map after pulmonary vein isolation demonstrated low-voltage areas with a peak-to-peak bipolar voltage of <0.5 mV covering ≥5 cm² of the left atrium.

RESULTS

LVAs were present in 206 (21%) patients. The SPEED score was obtained as the total number of independent predictors as identified on multivariate analysis, namely female sex (odds ratio [OR], 3.4 [95% confidence interval {CI} 2.2-5.2], p < .01), persistent AF (OR, 1.8 [95% CI, 1.1-3.0], p = .02), age ≥ 70 years (OR, 2.3 [95% CI, 1.5-3.4], p < .01), elevated brain natriuretic peptide ≥100 pg/ml or N-terminal probrain natriuretic peptide ≥400 pg/ml (OR, 1.7 [95% CI, 1.02-2.8], p = .04), and diabetes mellitus (OR, 1.8 [95% CI, 1.1-2.8], p = .02). LVAs were more frequent in patients with a higher SPEED score, and prevalence increased with each additional SPEED score point (OR, 2.4 [95% CI, 2.0-2.8], p < .01).

CONCLUSION

The SPEED score accurately predicts the prevalence of LVAs in patients undergoing ablation for AF.

Low-Voltage Areas as Alternative Targets for the Ablation of Unmappable Atrial Tachycardia in Patients Undergoing Atrial Fibrillation Ablation

Aims

Unmappable regular atrial tachycarrhythmias (ATs) occasionally develop during atrial fibrillation (AF) ablation, and are difficult to treat by conventional ablation. Recently, low-voltage areas (LVAs) have been reported to represent AT substrate. The purpose of this study was to elucidate the efficacy of LVA ablation for unmappable AT.

Methods

This observational study included 32 consecutive patients who developed unmappable ATs during and after AF ablation. Unmappable AT was defined as AT lasting for >5 s, but that terminated or changed the activation sequence over too short a time to create a sufficient activation map. We used conventional ablation to target undetermined AT circuits estimated from activation timings of electrograms recorded on the placed electrode catheter, the response to entrainment mappings, and/or diastolic potentials during AT. Subsequently, in cases without successful elimination of unmappable ATs by conventional ablation, LVA (≤ 0.5 mV) ablation was performed at the discretion of the operators.

Results

Conventional ablation failed to eliminate at least one unmappable AT in 29 patients. Among them, LVA ablation was performed in 16 patients. LVA ablation eliminated all the unmappable ATs in 8 of 16 patients. The LVA size did not differ between patients with and without the acute elimination of unmappable ATs (17±11 vs. 21±12 cm2, p = 0.39), and AT/AF recurrence rates were comparable between the two groups (38% vs. 63%, p = 0.62) during a mean follow-up period of 14±8 months.

Conclusions

LVA ablation was efficacious to some extent for the elimination of unmappable ATs refractory to conventional ablation.

Substrate Targeted Ablation of Atrial Fibrillation Guided by High Density Voltage Mapping: Long-Term Results

Background

Long-term ablation results for atrial fibrillation (AF) have been disappointing, particularly for non-paroxysmal AF (NPAF). We hypothesize fibrosis in paroxysmal AF (PAF) and NPAF would be reflected in voltage fragmentation and visualized by high density mapping. Targeted ablation of discrete low voltage bridges (LVB) would eliminate endocardial fragmentation and should have a positive effect on long-term sinus rhythm (SR) survival.

Objective

To assess the efficacy of LVB ablation on SR survival in patients with PAF and NPAF, as well as, determine its impact on P wave duration (PWD) and LA volume (LAV).

Methods

56 patients (29PAF/26NPAF) had a voltage gradient map (VGM) created, high and low voltage limits were adjusted to image LVB. Ablation was performed until no LVB were observed. Baseline PWD and LAV were obtained and reassessed 6 months' post ablation. Patients were followed for 5 years with intermittent monitors.

Results

Termination of AF in NPAF was 88%. PWD normalized in PAF and were normal in NPAF post ablation. LAV decreased significantly in NPAF. At 5 years, SR was observed in 89% of PAF and 67% of NPAF.

Conclusions

1. LVB ablation terminates AF in NPAF 88%; 2. Both PWD and LAV were improved; 3. Maintenance of SR was observed in 89% and 67% (PAF vs NPAF); 4. The present study demonstrates efficacy of a simplified, individualized, and unified methodology for AF ablation.

Additional Low-Voltage-Area Ablation in Patients With Paroxysmal Atrial Fibrillation: Results of the Randomized Controlled VOLCANO Trial

Background The efficacy of low-voltage-area (LVA) ablation has not been well determined. This study aimed to investigate the efficacy of LVA ablation in addition to pulmonary vein isolation on rhythm outcomes in patients with paroxysmal atrial fibrillation (AF). Methods and Results VOLCANO (Catheter Ablation Targeting Low-Voltage Areas After Pulmonary Vein Isolation in Paroxysmal Atrial Fibrillation Patients) trial included paroxysmal AF patients undergoing initial AF ablation. Of 398 patients in whom a left atrial voltage map was obtained after pulmonary vein isolation, 336 (85%) had no LVA (group A). The remaining 62 (15%) patients with LVAs were randomly allocated to undergo LVA ablation (group B, n=30) or not (group C, n=32) in a 1:1 fashion. Primary end point was 1-year AF-recurrence-free survival rate. No adverse events related to LVA ablation occurred. Procedural (124±40 versus 95±33 minutes, P=0.003) and fluoroscopic times (29±11 versus 24±8 minutes, P=0.034) were longer in group B than group C. Patients with LVAs demonstrated lower AF-recurrence-free survival rates (88%) than those without LVA (B, 57%, P<0.0001; C, 53%, P<0.0001). However, LVA ablation in addition to pulmonary vein isolation did not impact AF-recurrence-free survival rate (group B versus C, P=0.67). Conclusions The presence of LVA was a strong predictor of AF recurrence after pulmonary vein isolation in patients with paroxysmal AF. However, LVA ablation had no beneficial impact on 1-year rhythm outcomes. Registration URL: https://www.umin.ac.jp/ctr; Unique identifier: UMIN000023403.

Predictive value of noninducibility after catheter ablation for paroxysmal and persistent atrial fibrillation

Background

It is unclear whether pacing maneuver at the end of catheter ablation for atrial fibrillation (AF) predicts recurrence of atrial tachyarrhythmia postintervention.

Objective

To investigate whether the predictive value of incremental pacing maneuver after catheter ablation for AF depends on the pacing cycle length and type of AF.

Methods

This study included 298 consecutive patients who underwent initial catheter ablation for nonvalvular AF (61% paroxysmal AF [PAF], 39% persistent AF [PeAF]). Rapid atrial pacing was performed at the end of the procedure. We analyzed minimum coupling interval (CI) of pacing, arrhythmia‐inducibility, and atrial tachyarrhythmia recurrence in patients with PAF and PeAF.

Results

Patients were divided into the following three groups according to their response to pacing maneuver: AF‐inducible (inducible group; n = 86), noninducible at CI ≥200 ms (non‐CI ≥200 group; n = 100), and noninducible at CI <200 ms (non‐CI <200 group; n = 112). Kaplan‐Meier analysis showed that response to pacing maneuver was significantly associated with recurrence of atrial tachyarrhythmias (P = .028). Cox‐regression analysis showed that non‐CI <200 was an independent predictor when the inducible group was used as a reference (hazard ratio 0.60, 95% confidence interval 0.40‐0.96, P = .031). However, when PAF and PeAF were analyzed separately, non‐CI <200 was an independent predictor only in PeAF.

Conclusion

Noninducibility with shorter CI predicted atrial tachyarrhythmia recurrence only for PeAF. Pacing CI and type of AF could influence the predictive value of atrial tachyarrhythmia recurrence.

Slow whole left atrial conduction velocity after pulmonary vein isolation predicts atrial fibrillation recurrence

BACKGROUND

Atrial conduction velocity may represent atrial fibrillation (AF) substrate after pulmonary vein isolation (PVI). To elucidate the association between whole left atrial conduction velocity (LACV) and AF recurrence after PVI.

METHODS AND RESULTS

This observational study enrolled 279 patients (147 paroxysmal and 132 persistent AF) who underwent PVI alone as an initial AF ablation procedure. After PVI, the left atrium was mapped with a 20-pole multielectrode in conjunction with the CARTO3 system during 100-ppm right atrial pacing. Left atrial conduction distance and conduction time were calculated from the start to the end of the propagation wave front in the left atrium. LACVs on the anterior and posterior routes were calculated as conduction distance divided by conduction time. Anterior and posterior LACVs were slower in patients with AF recurrence than in those without (anterior, 0.79 [0.71, 0.86] vs 0.96 [0.90, 1.06] m/s, P < .001; posterior, 0.99 [0.89, 1.14] vs 1.10 [1.00, 1.29] m/s, P < .001). AF recurrence was best predicted by anterior LACV with a cut-off value of 0.87 m/s (sensitivity 87%, specificity 81%, and predictive accuracy 84%). Multivariate analysis demonstrated that a slow anterior LACV <0.87 m/s was an independent predictor of AF recurrence with an adjusted hazard ratio of 11.8 (6.36-22.0). Patients with anterior low-voltage areas demonstrated slower anterior LACV than those without low-voltage areas (0.89 [0.71, 1.00] vs 0.94 [0.87, 1.05] m/s, P < .001).

CONCLUSION

A slow anterior LACV was an excellent predictor of AF recurrence after PVI.

Role of inducibility and its dynamic change in the outcome of catheter ablation of atrial fibrillation: a single center prospective study

BACKGROUND

The role of atrial arrhythmia inducibility as an endpoint of catheter ablation of atrial fibrillation (AF) has been a controversial subject in many studies. Our goal is to evaluate the significance of inducibility, the impact of multiple sites or protocols of stimulation or the change in inducibility status in a prospective study including patients with AF undergoing first catheter ablation.

METHODS

We studied 170 consecutive patients with AF (62.9% paroxysmal) undergoing catheter ablation. All patients underwent two separate stimulation protocols before and after the ablation from the coronary sinus ostium and the left atrial appendage: burst pacing at 300, 250, 200 milliseconds (or until refractoriness) for 10 seconds and ramp decrementing from 300 to 200 milliseconds in increments of 10 milliseconds every three beats for 10 seconds. Inducibility was defined as any sustained AF or organized atrial tachycardia (AT) lasting >30 seconds.

RESULTS

We had AF/AT inducibility in 55 patients at baseline compared to 36 following ablation. After a mean of 41, 3 months follow-up, 115 patients were free of AF. Inducibility before or after the ablation or change in inducibility status did not influence AF recurrence. There were no significant differences regarding paroxysmal or persistent patients with AF.

CONCLUSIONS

Non-inducibility of atrial arrhythmia or change in inducibility status following pulmonary vein (PV) isolation and substrate modification are not associated with long-term freedom from recurrent arrhythmia. Therefore, the use of induction of an endpoint in AF ablation is limited.

Left atrial voltage mapping with a direction-independent grid catheter: Comparison with a conventional circular mapping catheter

INTRODUCTION

A recently introduced grid mapping catheter (GMC) is designed for better electrode-tissue contact and can collect bipolar signals both along and across the splines, which may allow more efficient voltage map generation independent of propagation direction. We compared the GMC with a conventional circular mapping catheter (CMC) for left atrial (LA) voltage mapping.

METHODS

This study included 20 consecutive patients undergoing repeat ablation for recurrent atrial fibrillation who had demonstrated LA low-voltage areas (LVAs, <0.10 mV). Following pulmonary vein isolation, LA voltage mapping was performed twice, once using the GMC and once using the CMC.

RESULTS

Voltage mapping was more efficient using the GMC than the CMC in terms of mapping time (459 [404, 543] vs 602 [496, 814] seconds; P = .014) and the number of mapping points (2446 [2099, 3104] vs 1841 [1494, 2314]; P = .002). The incidence of catheter-induced ectopies was lower (44 [28, 62] vs 114 [74, 188]; P < .0001) using the GMC. The GMC utilizing all bipoles detected LVAs in 85% of patients with LVAs detected by CMC. LVA measurements were significantly smaller on maps generated by the GMC using bipoles along or across the splines than those measured with the CMC (11.1 [4.6, 17.2] or 9.7 [2.5, 16.0] vs 16.4 [6.8, 26.8] cm² ; P = .008 and P = .001, respectively), and were even smaller when using all bipoles (7.9 [1.1, 13.5] cm² , P = .0001).

CONCLUSION

The GMC allowed a more efficient mapping procedure and enabled more selective identification of LVAs with smaller LVA size.

Efficacy and safety of the cryoballoon-based atrial fibrillation ablation in patients aged ≥80 years

INTRODUCTION

The prevalence of atrial fibrillation (AF) increases with age. Although the efficacy of cryoballoon ablation (CB-A) in patients with AF has been demonstrated, data on the efficacy of this CB-A in elderly patients are limited. The aim of this study was to evaluate the 1-year efficacy and safety of CB-A in patients aged ≥80 years compared with those less than 80 years.

METHODS

A total of 49 consecutive patients ≥80 years with paroxysmal AF (PAF) who underwent CB-A were compared with 241 patients aged <80 years. AF-free survival rate at 1 year and procedural data were compared between the groups.

RESULTS

Median (25th, 75th quartile) age was 83 (82, 85) years in the older group and 68 (61, 73) years in the younger group. At 1-year follow-up, the success rate did not significantly differ between the groups. In Cox regression analysis, age ≥80 years was not significantly related to AF recurrence. Low-voltage areas were more frequently observed in the elderly group than the control group (39% vs 17%; P = .01). Fluoroscopy time and procedure time did not differ significantly. There was no significant difference in the occurrence rate of transient phrenic nerve palsy. No severe complications occurred in either group, including procedure-related deaths, atrioesophageal fistula, cardiac tamponade, and cerebrovascular embolic events.

CONCLUSION

The results of our study showed that CB-A for PAF is a feasible and safe procedure even in elderly patients, with similar success and complication rates when compared with a younger population.

Association between prolonged P wave duration and left atrial scarring in patients with paroxysmal atrial fibrillation

BACKGROUND

We evaluated the association of P wave duration (PWD) with left atrial scar (LAS) in patients with paroxysmal atrial fibrillation (PAF).

METHODS

Consecutive patients with PAF undergoing their first catheter ablation were screened and only those in sinus rhythm at baseline were included in the analysis. A standard 12-lead electrocardiogram (ECG) was performed in all and three-dimensional voltage mapping of the left atrium was generated for identification of low-voltage areas (≤0.2 mV) before the procedure.

RESULTS

In total, 411 patients with PAF were included in this study of which 181 had LASs (scar group), while 230 had no scar (nonscar group). In the scar group, patients were older (65.5 ± 8.8 vs 59.7 ± 11.7 years; P < .001), the proportion of female was higher (47.5% vs 37.4%; P = .04) and left atrial (LA) diameter (4.1 ± 0.6 vs 3.9 ± 0.6 cm; P < .001) was larger compared with the nonscar group. There was no significant difference in terms of hypertension, sleep apnea, and diabetes between the two groups. When comparing ECG characteristics between the two groups, PWD was significantly longer in the scar group (122.9 ± 18.5 and 116.9 ± 28.0 ms; P = .01). A multivariate analysis was performed, after adjustment of age, sex, LA diameter, PWD ≥ 120 ms was found to be an independent predictor of LA scarring (OR: 1.69, p-value: 0.02).

CONCLUSION

In the current series, prolonged PWD was found to be independently associated with LA scarring in PAF, even after adjustment for age, sex, and LA diameter.

The impact of the presence of left atrial low voltage areas on outcomes from pulmonary vein isolation

BACKGROUND

AF ablation (AFA) with pulmonary vein isolation (PVI) is highly successful for paroxysmal atrial fibrillation (PAF). However, success rates for persistent AF (PsAF) are significantly lower. In this study we evaluate the impact of left atrial (LA) low voltage areas (LVA) on response to AFA.

METHODS

Consecutive patients undergoing first-time radiofrequency AFA were included (n = 160, 53% PAF). PVI was performed followed by LA voltage mapping during sinus rhythm. Patients were categorized as having LVA based on the presence of LVA (0.2-0.5 mV) in the LA assessed visually by the operator intra-procedurally. Further adjunctive LA ablation was performed at the operators' discretion. The end-point was recurrence of any sustained atrial arrhythmia (atrial fibrillation/tachycardia/flutter) during 12 months follow-up.

RESULTS

All patients had PVI and 23 (14%) had adjunctive LA ablation. LVA were found in 49 (31%) patients and were an independent predictor of arrhythmia recurrence. Patients with LVA compared to those without had significantly lower 12-month arrhythmia-free survival in both PAF (38% vs 76%; P = 0.002) and PsAF (27% vs 61%; P = 0.015). PsAF patients without LVA (93% had PVI alone) had similar arrhythmia-free survival to patients with PAF (61% vs 67%, respectively; P = 0.42). Recurrence in patients with LVA compared to those without was more likely to be an organized atrial arrhythmia rather than AF (16/30 recurrences vs 2/26, P < 0.001).

CONCLUSIONS

The presence of LVA predicts AFA success as well as the type of arrhythmia recurrence. The absence of LVA identifies PsAF patients that respond well to a PVI-based ablation strategy.

Comparison of electrogram waveforms between a multielectrode mapping catheter and a linear ablation catheter

BACKGROUND

Smaller low-voltage areas (LVAs) obtained by multielectrode catheters were reported than those by linear ablation catheters. However, the underlying electrogram difference has not been elucidated. This study aimed to compare the two mapping catheters' measurements of electrogram waveforms and LVAs.

METHODS

This prospective observational study included 17 consecutive patients undergoing ablation for persistent atrial fibrillation. Following pulmonary vein isolation, voltage mapping during sinus rhythm was performed once using the ablation catheter, and once using the multielectrode catheter. Approximately 20 pairs of mapping points at approximately the same position between the two voltage maps were manually selected evenly throughout the left atrium.

RESULTS

Voltage mapping with the multielectrode catheter demonstrated smaller LVAs, defined as <0.50 mV (5.9 [3.3, 11.0] vs 9.7 [6.6, 16.9] cm² ) than those mapped with the ablation catheter. The two mapping catheters' voltage amplitudes of all pairs of mapping points correlated well (r = 0.81, P < 0.0001) overall, but they did not correlate within diseased areas (either voltage <0.50 mV). The voltage amplitude difference between the two catheters ([Vol_Multi  - Vol_Abl ]/Vol_Abl × 100) was greater in the diseased areas (37.4% [-9.8%, 147%]) than in the healthy areas (both voltages ≥0.50 mV, 26.2% [-13.0%, 92.8%], P = 0.014). The electrogram waveform of the multiple electrode catheter displayed a higher voltage amplitude, shorter duration, greater number of peaks, and lower dull peak ratio (number of dull peaks/total peaks) than that of the ablation catheter.

CONCLUSION

The multielectrode catheter produced smaller LVA measurements with sharper and higher voltage electrograms compared to the ablation catheter, specifically in diseased areas.

Impact of Renal Dysfunction on Left Atrial Low-Voltage Areas in Patients With Atrial Fibrillation

BACKGROUND

The presence of residual left atrial low-voltage areas (LVA) has been shown to be strongly associated with atrial fibrillation (AF) recurrence after pulmonary vein isolation. A preliminary study showed that concomitant chronic kidney disease (CKD) increased the rate of AF recurrence. The association between CKD and LVA, however, has not been elucidated. In the present study, we investigated the association between CKD severity and LVA prevalence. Methods and Results: In total, 183 consecutive AF patients who underwent initial ablation for AF were enrolled in this retrospective observational study. Serum cystatin C before ablation was measured, and the estimated glomerular filtration rate (eGFR) was calculated. LVA were defined as sites of left atrial electrogram amplitude <0.5 mV. Of 183 patients, 76 (42%) had LVA. Patients with LVA had lower eGFR calculated using cystatin C (74±22 vs. 86±24 mL/min/1.73 m², P=0.001). The optimal cut-off of the calculated eGFR was 71.5 mL/min/1.73 m², corresponding to a 79.4% sensitivity, 50% specificity, and 67.2% predictive accuracy. LVA occurred more frequently in patients with more severe categories of CKD. On multivariate analysis, eGFR <71.5 mL/min/1.73 m²was an independent predictor of LVA (odds ratio, 3.3; 95% CI: 1.4-7.8; P=0.006).

CONCLUSIONS

CKD severity was correlated with left atrial LVA prevalence in patients with AF undergoing catheter ablation.

Bipolar Voltage Mapping for the Evaluation of Atrial Substrate: Can We Overcome the Challenge of Directionality?

The relationship between atrial fibrosis and atrial fibrillation (AF) has been proven. Patient specific substrate ablation targeting fibrotic tissue estimated by bipolar voltage mapping has emerged as an alternative strategy for additional substrate modification beyond pulmonary vein isolation. The primary mechanism of a low-voltage electrogram has been suggested to be atrial fibrosis, however, no direct correlation between histological fibrosis and low-voltage zone has been confirmed. Furthermore, the definition of low-voltage zone is still controversial, and bipolar voltage amplitudes depend on multiple variables including electrodes orientation relative to direction of wavefront, electrode length, interelectrode spacing, and tissue contact. The aim of this article is to review the role and limitation of voltage mapping, and to share our initial experience of a newly released grid-pattern designed mapping catheter to make the voltage mapping more reliable to guide patient specific AF ablation.

Targeted ablation of specific electrogram patterns in low-voltage areas after pulmonary vein antral isolation in persistent atrial fibrillation: Termination to an organized rhythm reduces atrial fibrillation recurrence

BACKGROUND

Ablation strategies have been developed to improve outcomes in patients with persistent atrial fibrillation (PsAF). However, the impact of atrial fibrillation (AF) termination on late AF recurrence is not well known. The aim of our study was to evaluate the impact of AF termination to atrial tachycardia (AT) or sinus rhythm (SR) during catheter ablation on late AF recurrence after the 3-month blanking period.

METHODS AND RESULTS

We prospectively recruited 140 patients (mean age: 58.5 ± 12.3 years old, 74.3% males) with uninterrupted PsAF of a mean duration of 3.7 months. Pulmonary vein antral isolation (PVAI) was the first ablation step, and if AF did not terminate (to SR or AT), we ablated low-voltage areas less than 0.4 mV with specific electrogram characteristics. We successfully converted AF to AT or SR in 56 patients (40%) during PVAI (n = 24) or low-voltage ablation ( n = 32). The remaining 84 patients (60%) were electrically cardioverted to SR at the end of the procedure. One hundred patients (71.4%) maintained SR after a single procedure during a mean follow-up of 21.1 ± 0.8 months. Of the 56 patients with AF termination, 46 (82.1%) had no recurrence, while in the group of 84 patients without AF termination, 54 patients (64.3%) remained in SR ( P < 0.02).

CONCLUSION

Ablation of PVAI and specific electrograms in low-voltage areas less than 0.4 mV can lead to encouraging outcomes with a low recurrence rate as well as a lower need for redo procedures.

Left atrial low-voltage areas predict atrial fibrillation recurrence after catheter ablation in patients with paroxysmal atrial fibrillation

BACKGROUND

Association between the presence of left atrial low-voltage areas and atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) has been shown mainly in persistent AF patients. We sought to compare the AF recurrence rate in paroxysmal AF patients with and without left atrial low-voltage areas.

METHODS

This prospective observational study included 147 consecutive patients undergoing initial ablation for paroxysmal AF. Voltage mapping was performed after PVI during sinus rhythm, and low-voltage areas were defined as regions where bipolar peak-to-peak voltage was <0.50mV.

RESULTS

Left atrial low-voltage areas after PVI were observed in 22 (15%) patients. Patients with low-voltage areas were significantly older (72±6 vs. 66±10, p<0.0001), more likely to be female (68% vs. 32%, p=0.002), and had higher CHA₂DS₂-VASc score (2.5±1.5 vs. 1.8±1.3, p=0.028). During a mean follow-up of 22 (18, 26) months, AF recurrence was observed in 24 (16%) and 16 (11%) patients after the single and multiple ablation procedures, respectively. AF recurrence rate after multiple ablations was higher in patients with low-voltage areas than without (36% vs. 6%, p<0.001). Low-voltage areas were independently associated with AF recurrence even after adjustment for the other related factors (Hazard ratio, 5.89; 95% confidence interval, 2.16 to 16.0, p=0.001).

CONCLUSION

The presence of left atrial low-voltage areas after PVI predicts AF recurrence in patients with paroxysmal AF as well as in patients with persistent AF.

Impact of a prolonged interatrial conduction time for predicting the recurrence of atrial fibrillation after circumferential pulmonary vein isolation of persistent atrial fibrillation

There are some cases that are difficult to cure with only circumferential pulmonary vein isolation (CPVI) of persistent atrial fibrillation (PerAF). Recently, prolonged interatrial conduction times (IACTs), which seem to be associated with progressive remodeled atria, have been reported as a predictor of new-onset AF. This study aimed to investigate the prognostic value of a prolonged IACT for predicting AF recurrences after CPVI of PerAF. One hundred thirteen patients who underwent CPVI without an empirical substrate modification of PerAF were retrospectively analyzed. The IACT was defined as the interval from the earliest P-wave onset on the ECG to the latest activation in the coronary sinus and was measured after achieving the CPVI and conversion to sinus rhythm. During a mean 22.7-month follow-up after the initial procedure, 56 patients (50%) had AF recurrences. Patients with AF recurrence had a longer IACT than those without AF recurrence (p < 0.001). The best discriminative cut-off value for the IACT was 123 ms (sensitivity 53%, specificity 85%). In a Cox multivariate analysis, a prolonged IACT of ≥ 123 ms was the only independent predictor (hazard ratio: 2.38; 95% confidence interval: 1.36-4.16, p = 0.002) of being associated with the incidence of an AF recurrence. Even after multiple CPVI procedures, patients with an IACT ≥ 123 ms had a higher AF recurrence rate than those with an IACT < 123 ms (p = 0.002). In conclusion, a prolonged IACT of ≥ 123 ms may be a useful marker for predicting AF recurrences after both initial and multiple CPVI procedures for PerAF.

Low voltage areas in paroxysmal atrial fibrillation: The prevalence, risk factors and impact on the effectiveness of catheter ablation

BACKGROUND

The prevalence, risk factors of left atrial low voltage areas (LVA) in paroxysmal atrial fibrillation (PAF) and the impact of LVA on the effectiveness of circumferential pulmonary vein isolation (CPVI) were not fully clarified.

METHODS

One hundred fifty patients (mean age 64.7 years, 89 males) with PAF were consecutively enrolled to undergo CPVI. Prior to ablation a contact force sensing ablation catheter was utilized for LVA mapping in sinus rhythm. The patients were graded based on the proportion of LVA (LVA%): non LVA, mild (LVA% ≤ 10%), moderate (LVA% 10%-<20%) and severe (LVA% ≥ 20%), and were followed up for 12 months after initial CPVI.

RESULTS

There were 56 in non LVA, 54 in mild LVA, 22 in moderate LVA and 18 in severe LVA. The prevalence of LVA was 62.7% in this PAF cohort, with the most frequent localization at anterior free wall (35.3%), PV antrum (22%) and septum (14.7%). Female gender (OR 3.634, 95% CI 1.704-7.751, P = 0.001) and left atrial surface area (LASA) (OR 1.024, 95% CI 1.000-1.048, P = 0.048) were risk factors of LVA. LVA% exceeding10% was associated with poor effectiveness of CPVI. LVA grade (HR 1.633, 95% CI 1.122-2.378, P = 0.011) was an independent predictor for AF recurrence after initial ablation.

CONCLUSIONS

LVA affected >60% of patients with PAF. Female gender and LASA were two risk factors of LVA. LVA grade was an independent predictor for AF recurrence following CPVI.

Low-voltage areas detected by high-density electroanatomical mapping predict recurrence after ablation for paroxysmal atrial fibrillation

INTRODUCTION

We aimed to evaluate the extent of atrial fibrosis in paroxysmal atrial fibrillation (AF) and the correlation with ablation outcomes after pulmonary vein antral isolation (PVΑI) using a mapping system with high-resolution and high-spatial sampling.

METHODS AND RESULTS

We prospectively enrolled 80 consecutive patients (45 males, median age 60.26 years) with symptomatic paroxysmal AF who were scheduled for PVAI. Prior to PVAI, high-density bipolar voltage mapping (median number of 2,485 points) was carried out during sinus rhythm in all patients. Criteria for an adequate left atrium (LA) shell were > 2,000 points. Each acquired point was classified according to the peak-to-peak bipolar voltage electrogram based on two criteria (criterion A: healthy > 0.8 mV, border zone: 0.4-0.8 mV and scarred: < 0.4 mV, criterion Β: healthy: > 0.5 mV, border zone: 0.25-0.5 mV and scarred: < 0.25 mV). The extent of low-voltage area < 0.4 mV significantly predicted atrial tachyarrhythmia recurrence after the blanking period (P = 0.002). In univariate analysis, the presence of LA voltage areas < 0.4 mV more than 10% of the total surface area was the only significant predictor of arrhythmia recurrence. The analysis based on window B cutoff values failed to demonstrate any predictors of arrhythmia recurrence.

CONCLUSION

These data demonstrate that the existence of LA voltage areas < 0.4 mV more than 10% of the total LA surface area predicts arrhythmia recurrence following PVAI for paroxysmal AF.

Association Between Local Bipolar Voltage and Conduction Gap Along the Left Atrial Linear Ablation Lesion in Patients With Atrial Fibrillation

A bipolar voltage reflects a thick musculature where formation of a transmural lesion may be hard to achieve. The purpose of this study was to explore the association between local bipolar voltage and conduction gap in patients with persistent atrial fibrillation (AF) who underwent atrial roof or septal linear ablation. This prospective observational study included 42 and 36 consecutive patients with persistent AF who underwent roof or septal linear ablations, respectively. After pulmonary vein isolation, left atrial linear ablations were performed, and conduction gap sites were identified and ablated after first-touch radiofrequency application. Conduction gap(s) after the first-touch roof and septal linear ablation were observed in 13 (32%) and 19 patients (53%), respectively. Roof and septal area voltages were higher in patients with conduction gap(s) than in those without (roof, 1.23 ± 0.77 vs 0.73 ± 0.42 mV, p = 0.010; septal, 0.96 ± 0.43 vs 0.54 ± 0.18 mV, p = 0.001). Trisected regional analyses revealed that the voltage was higher at the region with a conduction gap than at the region without. Complete conduction block across the roof and septal lines was not achieved in 3 (7%) and 6 patients (17%), respectively. Patients in whom a linear conduction block could not be achieved demonstrated higher ablation area voltage than those with a successful conduction block (roof, 1.91 ± 0.74 vs 0.81 ± 0.51 mV, p = 0.001; septal, 1.15 ± 0.56 vs 0.69 ± 0.31 mV, p = 0.006). In conclusion, a high regional bipolar voltage predicts failure to achieve conduction block after left atrial roof or septal linear ablation. In addition, the conduction gap was located at the preserved voltage area.

Catheter ablation of atrial fibrillation with box isolation of fibrotic areas: Lessons on fibrosis distribution and extent, clinical characteristics, and their impact on long-term outcome

INTRODUCTION

The BIFA concept (box isolation of fibrotic areas) supplementing pulmonary vein isolation (PVI) was implemented in atrial fibrillation (AF) patients with fibrotic atrial cardiomyopathy (FACM) to improve catheter ablation outcomes.

METHODS AND RESULTS

Ninety-two patients with FACM underwent PVI + BIFA. We investigated patient characteristics (58 persistent/34 paroxysmal, 68 ± 8 years, LA 44 ± 7 mm, CHA₂ DS₂ -VASc 2.6 ± 1.3, FACM I: 15.2%, II: 53.3%, III: 26.1%, IV: 5.4%), periprocedural data concerning fibrosis extent/distribution, and their impact on outcome. Based on severe fibrosis areas (SFAs) of 13.5 ± 13.9 cm² detected by voltage mapping, 1.4 ± 0.5 boxes (n = 1-3, 2.2-35.3 cm² ) were applied in the left atrium. With higher grade FACM, SFAs increased and maximum voltage decreased (I/IV: 6.29/3.18 mV). Anterior (ant.) SFAs were found to be more common and larger than posterior (post.) SFAs (58.3% vs. 42.6%, ant. 8.0 ± 8.0 vs. post. 4.7 ± 6.8 cm² ). In 40 of 92 (43%) patients, both atrial walls were affected with rare cases of solely post. fibrosis (6 of 92, 6.6%). Women (39 of 92, 42%) showed FACM III+IV more often than men (P = 0.022) and can still present paroxysmal while persistent males are more likely to have FACM I-II. Single and multiple procedure (1.2/patient) success was 69% and 83% after 16 ± 8 months with an unfavorable impact of large SFA size, both-sided fibrosis and reduced maximum voltage, independently of patient characteristics and AF type.

CONCLUSION

FACM patients are a challenging AF subgroup for catheter ablation. Women seem to show FACM III+IV more often than men. The distribution of left atrial fibrosis is variable but more pronounced anteriorly. Atrial disease is characterized by SFA size but also maximum voltage reduction, both with implications on ablation outcome. Using BIFA, success rates of patients without fibrosis can be approached but are limited in FACM III+IV.

Frequency Gradient Within Coronary Sinus Predicts the Long-Term Outcome of Persistent Atrial Fibrillation Catheter Ablation

Background

The coronary sinus (CS), as a junction of the atria, contributes to atrial fibrillation (AF) by developing unstable reentry, and isolating the atria by ablation at the CS could terminate AF. The present study evaluated whether AF activities at the CS in a subset of patients contributed to AF maintenance and predicted clinical outcome of ablation.

Methods and Results

We studied 122 consecutive patients who had a first‐time radiofrequency ablation for persistent AF. Bipolar electrograms were obtained from multiple regions of the left atrium by a Lasso mapping catheter before ablation. Pulmonary vein isolation terminated AF in 12 patients (9.8%). Sequential stepwise ablation was conducted in pulmonary vein isolation nontermination patients and succeeded in 22 patients (18%). In the stepwise termination group, AF frequency in the proximal CS (CSp) was significantly higher (10.2±2.1 Hz versus 8.3±1.8 Hz, P<0.001), and the ratio of distal CS (CSd) to proximal CS (CSd/CSp ratio, 56.6%±10.11% versus 70.7%±9.8%, P<0.001) was significantly lower than that in the nontermination group. The stepwise logistic regression analysis indicated that the CSd/CSp ratio was an independent predictor with an odds ratio of 1.131 (95%CI 1.053‐1.214; P=0.001). With a cutoff of 67%, the patients with lower CSd/CSp ratios had significantly better index and long‐term outcomes than those with higher ratios during a follow‐up of 46±18 months.

Conclusions

Rapid repetitive activities in the musculature of the proximal CS may contribute to maintenance of AF after pulmonary vein isolation alone in persistent AF. A cutoff at 67%, of the CSd/CSp frequency ratio might be an indicator to stratify the subset of patients who might benefit from CS ablation.