Differences in the electrophysiological findings of repeat ablation between patients who first underwent cryoballoon ablation and radiofrequency catheter ablation for paroxysmal atrial fibrillation

Comparison of advanced generation cryoballoon ablation and ablation index-guided pulmonary vein isolation with non-pulmonary vein trigger induction test and additional ablation in paroxysmal atrial fibrillation

BACKGROUND

An ablation index (AI)-guided pulmonary vein isolation (PVI) or 2nd generation cryoballoon (CB)-PVI has been shown to reduce the atrial fibrillation (AF) burden by 99% despite the absence of ablation of non-pulmonary vein (PV) triggers in patients with paroxysmal AF. The purpose of this study was to investigate the effects of PVI alone strategy using 2nd generation CB compared with AI-guided PVI with an additional induction test and subsequent AF trigger ablation.

METHODS AND RESULTS

We investigated 223 patients with symptomatic paroxysmal AF who underwent an initial PVI between August 2018 and August 2020. The study patients were divided into 2 groups: CB-PVI without an induction test (CB-PVI alone group, n = 82) and AI-guided PVI with an induction test and subsequent additional ablation of non-PV triggers (AI-PVI plus group, n = 141). In the AI-PVI plus group, a total of 62 non-PV triggers were induced in 38 patients, and non-PV triggers in 22 patients were completely ablated. The procedure time and left atrium dwell time were significantly shorter in the CB-PVI alone group than AI-PVI plus group. There were no significant differences in the incidence of procedural complications between the 2 groups (P = 0.650). The AF free survival rate in the CB-PVI alone group and AI-PVI plus group was 80% vs. 80% at 24 months (P = 0.969).

CONCLUSIONS

An PVI alone strategy using advanced generation CB did not differ in the clinical outcomes compared with an AI-guided PVI strategy with an induction test and subsequent ablation of non-PV triggers in the patients with paroxysmal AF.

Chronic Ablation Lesions after Cryoballoon and Hot Balloon Ablation of Atrial Fibrillation

BACKGROUND

Chronological changes in ablation lesions after cryoballoon ablation (CBA) and hot balloon ablation (HBA) of atrial fibrillation (AF) remain unclear.

METHODS

Of 90 patients who underwent initial balloon-based catheter ablation of AF and cardiac magnetic resonance imaging (cMRI) 3 months after ablation, data from 48 propensity score-matched patients (24 per group; 34 males; age 62±10 years) were analyzed. High-density pulmonary vein-left antrum (PV-LA) voltage mapping was performed after PV isolation, and low voltage areas around the PV ostia were defined as the total acute ablation lesion area (cm²). cMRI-derived dense fibrotic tissue localized around PVs was defined as the total chronic ablation lesion area (cm²). The percentage of total ablation lesion areas to total PV-LA surface area (%ablation lesion) was calculated during each phase, and %acute ablation lesion and %chronic ablation lesion areas were compared in patients who had undergone CBA and HBA.

RESULTS

The %acute ablation lesion area was larger for the CBA group than for the HBA group (30.8±5.8% vs. 23.0±5.5%, p < 0.001). There was no difference in %chronic cMRI-derived ablation lesion area (24.8±10.8% vs. 21.1±11.6%, p = 0.26) between groups. The rates of chronic AF recurrence were 12.5% and 8.3%, respectively (p = 0.45; log-rank test). LA volume and LA surface area were strongly associated with AF recurrence, but %chronic ablation lesion area was not (27±8% vs. 23±12%, p = 0.39).

CONCLUSION

Large acute ablation lesions after CBA were smaller during the chronic phase. The size of chronic ablation lesions and the rate of AF recurrence were both similar for CBA and HBA.

Optimal single procedure strategy of pulmonary vein isolation with cryoballoon or radiofrequency and non-pulmonary vein triggers ablation for non-paroxysmal atrial fibrillation

Background

Limited data exist on pulmonary vein isolation (PVI) using cryoballoon (CB) or radiofrequency (RF) ablation and additional non-pulmonary vein trigger ablation for non-paroxysmal atrial fibrillation (non-PAF). We aimed to assess the outcomes of first-stage catheter ablation for non-PAF patients.

Methods

Initial PVI was performed on 734 non-PAF patients (age: 64 ± 10 years; male: 584 (80%)) between September 2014 and June 2018 [315 (43%), CB ablation; 419 (57%), RF catheter]. A logistic regression model was used to match 257 pairs (514 patients) according to the propensity scores (CB or RF group). After PVI, additional non-PV trigger ablation was performed if induced by isoproterenol. We analysed the clinical outcomes of both groups.

Results

The mean procedural time was significantly shorter in the CB group (125 [range, 89–165] min) than in the RF group (190 [160–224] min; P < 0.001). The 1-year Kaplan-Meier event rate revealed similar atrial fibrillation-free survival rates between the two groups (CB: 77.9%, RF: 82.3%; log-rank P = 0.111). The additional ablation percentage for non-PV foci (CB: 39%, RF: 41%; P = 0.653) and complication incidence (CB: 5%, RF: 4%; P = 0.670) were also similar.

Conclusions

In non-PAF patients, the combination strategy of PVI using CB or RF ablation and non-PV trigger ablation achieved comparable outcomes.

Evaluation of cryoballoon pulmonary vein isolation lesions during the acute and chronic phases using a high-resolution mapping system

BACKGROUND

An acute cryothermal ablation lesion contains both reversible and irreversible elements. However, differences in lesions created with cryoballoon pulmonary vein isolation (PVI) between the acute and chronic phases have not been fully elucidated.

METHODS

We retrospectively analyzed 23 consecutive patients with atrial fibrillation who underwent cryoballoon PVI during the initial procedure followed by a second ablation procedure. In all patients, cryoballoon PVI lesions were evaluated with high-resolution voltage mapping just after PVI (acute phase) and during the second session (chronic phase). We compared the area and width of the non-isolated left atrial posterior wall (NI-LAPW) with voltage ≥ 0.5 mV during both sessions.

RESULTS

PVI was successfully achieved in all patients. Cryoballoon PVI lesions were re-evaluated at 11 [2-17] months post-procedure. During the chronic phase, NI-LAPW width became significantly larger at the level of the roof (change, 5.8 ± 5.5 mm; p < 0.001) and at the level of the carina (change, 3.3 ± 7.0 mm; p < 0.05), and NI-LAPW area became significantly larger (change, 1.5 ± 1.9 cm²; p < 0.001) compared with the acute phase. Eight patients without any PV reconnections also had larger NI-LAPW areas (change, 1.3 ± 1.2 cm²; p < 0.05) during the chronic phase. Conduction resumption confined to the right carina was observed in 1 (4.3%) patient who presented with circumferential PVI that included the carina during the first session.

CONCLUSION

Acute cryoballoon PVI lesions significantly regressed during the chronic phase. PV reconnections and the isolation area should be carefully re-evaluated during the second procedure.

The immediate trends in atrial electrical remodeling for paroxysmal atrial fibrillation across different modes of catheter ablation

Background

Catheter ablation has emerged as a major strategy for paroxysmal atrial fibrillation (PAF). Atrial electrical remodeling (AER) plays a critical role in the recurrence of PAF after ablation.

Hypothesis

To characterize the immediate trends of AER during ablations in patients with PAF, and assess the relationship between immediate trends and recurrence.

Methods

We performed this prospective observational study of 135 patients to investigate AER following three ablation modes: radiofrequency ablation (RFA), cryoablation (CA) and 3D mapping‐guided cryoablation (3D‐CA). The atrial effective refractory period (AERP) and atrial conduction time (ACT) were measured via electrophysiology before and immediately after ablation, and P‐wave indices were measured via electrocardiography before and within 24 h after ablation. Follow‐up visits were conducted for at least 1 year or until relapse.

Results

Different approaches of ablation caused a fairly significant increase in the shortest P‐wave duration and AERP in both the proximal coronary sinus (PCS) and distal coronary sinus (DCS) but caused a shortened P‐wave dispersion. No different effect was found at the AERP among the three modes. Compared to patients who received CA, among patients who received RFA, a significant reduction in total ACT and right ACT was seen. Statistically, there was a weakly positive association between changes in total ACT and early recurrence.

Conclusions

Injury during ablation for PAF was associated with an increase in the AERP but not in the ACT. Total ACT and right ACT were shorter after RFA than after CA. The increase in total ACT were slightly predictive of early recurrence.

Catheter ablation for atrial fibrillation in patients with congestive heart failure

BACKGROUND

We evaluated the 1-year success rate of maintaining sinus rhythm after catheter ablation (CA) for atrial fibrillation (AF) in patients with or without congestive heart failure (CHF).

METHODS

In this single-centre retrospective matched-pair cohort study of 3,018 AF patients who underwent initial CA between January 2012 and June 2018, 227 pairs with (CHF group) or without CHF (control group) were matched using propensity scores. In the CHF group, 108 patients were assigned to the arrhythmia-induced cardiomyopathy (AIC) group whose left ventricular systolic dysfunction was explained only by lasting AF or atrial tachycardia; the remaining 119 had organic heart diseases (non-AIC group). We evaluated the 1-year AF-free survival and changes in clinical findings before and after CA.

RESULTS

The CHF and control groups showed similar AF-free survival; however, AIC patients had significantly better survival than non-AIC patients. AF recurrence was significantly related to CHF re-hospitalisation, which was significantly more frequent in the non-AIC group than in the AIC group. The clinical outcomes of left atrial dilation, brain natriuretic peptide level, and left ventricular ejection function improved significantly before and after CA in both groups. The degree of improvement was significantly better in the AIC group than in the non-AIC group.

CONCLUSIONS

The 1-year success rate was not significantly different between the CHF and control groups. The 1-year success rate in the AIC group was similar to that in the AIC-control group and was better than that in the non-AIC group. CHF clinical outcomes were improved significantly.

Presence of non-pulmonary vein foci in patients with atrial fibrillation undergoing standard ablation of pulmonary vein isolation: Clinical characteristics and long-term ablation outcome

Background

The clinical characteristics of atrial fibrillation (AF) resulting from non-pulmonary vein (PV) triggers remain unknown. This study aimed to evaluate the clinical characteristics of patients with AF caused by non-PV triggers, localization of non-PV foci, clinical differences, and clinical outcomes after catheter ablation in each AF focus.

Methods

A total of 2967 patients who underwent initial catheter ablation for paroxysmal or persistent AF were examined. After PV isolation, all patients underwent high-dose isoproterenol infusion to assess the existence of non-PV foci.

Results

Non-PV foci were identified in 564 patients (19.2%). The localization of successfully ablated non-PV foci in 514 patients were the superior vena cava (SVC: 213 cases), interatrial septum (IAS: 125 cases), coronary sinus (CS: 98 cases), right atrium (RA: 125 cases), left atrium (LA: 114 cases), and unmappable (50 cases). Multivariate analysis revealed that female gender, low body mass index (BMI), non-paroxysmal AF (PAF), and sick sinus syndrome were independent and significant indicators of non-PV foci. In the multivariate analysis of each AF focus, female gender, low BMI, and non-PAF were significant predictors of IAS and CS foci, RA and IAS foci, and CS foci, respectively. In addition, dilatation of the LA was significantly associated with LA foci, whereas RA, LA, IAS, and CS foci were associated with AF recurrence.

Conclusion

These findings could help to identify patients at a higher risk of AF caused by non-PV triggers and clarify the clinical difference according to the localization of non-PV foci.

The impact of left atrium size on selection of the pulmonary vein isolation method for atrial fibrillation: Cryoballoon or radiofrequency catheter ablation

BACKGROUND

Pulmonary vein isolation (PVI) is the cornerstone of ablation strategies for atrial fibrillation (AF), and noninferiority of cryoballoon (CB) over radiofrequency (RF) ablation has been previously reported. One of the risk factors of recurrence is left atrium (LA) enlargement. This study aimed to analyze the impact of LA enlargement on the selection of CB or RF ablation for AF patients.

METHODS

A total of 2,224 AF patients (64.4 ± 10.7 years, 65.5% male) who underwent PVI were analyzed retrospectively. Left atrial diameter (LAD) and volume (LAV) were measured using echocardiography before the procedures. LA enlargement was defined as LAD ≥40 mm and LAV index (LAVI) ≥35 mL/m². Patients undergoing CB and RF ablation were propensity score matched, and 376 matched pairs were evaluated.

RESULTS

Cox proportional hazard analysis revealed that LAD (95% CI, 1.01-1.05), LAV (95% CI, 1.01-1.02), and LAVI (95% CI, 1.01-1.03) were independent predictors of recurrence. CB showed equivalent clinical outcomes to those of RF with shorter procedure time required for patients without LA enlargement. CB was inferior to RF in patients with LA enlargement (LAD, 74.5% vs 84.6%, P = .028; LAVI, 74.7% vs 83.4%, P = .015), and large LAVI was associated with a higher prevalence of non-PV foci (35% vs 29%, P = .008).

CONCLUSIONS

CB ablation may be recommended for patients without enlarged LA based on the short procedure time and efficacy, whereas RF would be more appropriate in large LAs. LAVI may be a valuable reference to predict PVI outcomes and in selecting the ablation method.

Association between the locations of non-pulmonary vein triggers and ablation outcomes in repeat procedures after cryoballoon ablation of paroxysmal atrial fibrillation

PURPOSE

We examined the characteristics of non-pulmonary vein (PV) triggers in repeat ablation after cryoballoon ablation for paroxysmal atrial fibrillation (PAF).

METHODS

This study evaluated 119 patients undergoing a second ablation procedure for recurrent atrial tachyarrhythmia (ATA) after cryoballoon PV isolation (CB-PVI) for PAF.

RESULTS

Fifty-three of 119 (45%) patients had PV reconnection. All reconnected PVs were isolated. No non-PV triggers were elicited in 42/119 (35%) patients (NNPV group). In 77/119 (65%) patients, 139 isoproterenol-induced non-PV triggers, including 45 triggers that initiated AF, were identified. Non-PV triggers initiating AF were observed at the superior vena cava (SVC), left atrial posterior wall (LAPW) including the PV antra, interatrial septum, right atrium, left atrial appendage/mitral anulus, and coronary sinus in 14 (12%), 10 (8%), 8 (7%), 7 (6%), 4 (3%), and 2 (2%) patients, respectively. Non-PV triggers originated from only the SVC and/or LAPW including the PV antra, and the SVC and/or LAPW was isolated in 18/119 (15%) patients (SVC/LAPW group). Non-PV triggers originating from other sites were focally ablated in 59/119 (50%) patients (OS group). During a median 461 days of follow-up, 39/42 (93%), 17/18 (94%), and 38/59 (64%) patients in the NNPV, SVC/LAPW, and OS groups, respectively, remained ATA recurrence-free. The recurrence rate was higher in the OS group than in the NNPV (P = 0.005) or SVC/LAPW groups (P = 0.042).

CONCLUSIONS

Over half of patients had non-PV triggers at subsequent ablation after CB-PVI. Non-PV triggers from the SVC/LAPW can be eliminated more successfully than triggers from other sites.

Electrophysiological findings in patients with isolated veins after cryoablation for paroxysmal atrial fibrillation

AIMS

The main cause of atrial fibrillation recurrence after catheter ablation is pulmonary vein reconnection. The purpose of this retrospective study was to analyse the electophysiological findings in patients undergoing repeat procedures after an index cryoballoon ablation (CB-A) and presenting with permanency of pulmonary vein isolation (PVI) in all veins. In addition, we sought to compare the latter with a similar group of patients with reconnected veins at the redo procedure.

METHODS

A total of 132 patients (81 men, 60.7 ± 12.4 years) who underwent CB-A for paroxysmal atrial fibrillation (PAF) were enrolled. Indication for the redo procedure was symptomatic PAF in 83 (63%), persistent atrial fibrillation (PerAF) in 32 (24%) or persistent regular atrial tachycardia (RAT) in 17 (13%) patients.

RESULTS

Seventy-five (57%) patients presented a pulmonary vein reconnection (pulmonary vein group) during the redo procedure, whereas 57 (43%) had no pulmonary vein reconnection (non-pulmonary vein group). The non-pulmonary vein group exhibited significantly more non-pulmonary vein foci and atrial flutters than the pulmonary vein group after induction protocol (51 vs. 24%, P = 0.002 and 67 vs. 36%, P = 0.003, respectively). Twenty-two (29.3%) patients of the pulmonary vein group and 20 (35%) patients of the non-pulmonary vein group had atrial fibrillation/RAT recurrence after a mean follow-up of 12.5 ± 8 months. The survival analysis demonstrated no statistical significance in recurrence between both groups (log rank P = 0.358).

CONCLUSION

Atrial fibrillation/RAT recurrence in patients after CB-A with durable PVI is significantly associated with non-pulmonary vein foci and atrial flutters. No statistically different success rate regarding atrial fibrillation/RAT freedom was detected between the pulmonary vein and non-pulmonary vein groups after redoing RF-CA.

Cryoballoon or radiofrequency ablation? Alternating technique for repeat procedures in patients with atrial fibrillation

BACKGROUND

Which technique is better for repeat ablation in patients with atrial fibrillation (AF) remains unclear. The aim of the study was to compare long-term efficacy of repeat ablation using the alternative technique for the first redo ablation procedure: (a) cryoballoon (CB) re-ablation after a failed index pulmonary vein isolation (PVI) with radiofrequency (RF) ablation, RF-then-CB group or (b) RF repeat ablation following a failed CB ablation, CB-then-RF group.

METHODS

Within the 1STOP Italian Project, consecutive patients undergoing repeat ablation with a different technique from the index procedure were included.

RESULTS

We studied 474 patients, 349 in RF-then-CB and 125 in CB-then-RF group. Less women (21% vs 30%; P = .041), more persistent AF (33% vs 22%; P = .015), longer duration of AF (60 vs 31 months; P < .001), and more hypertension (50% vs 36%; P = .007) were observed in the RF-then-CB cohort as compared with the CB-then-RF group. The number of reconnected PVs was 3.7 ± 0.7 and 1.4 + 1.3 in RF-then-CB and CB-then-RF group, respectively (P < .001). During the follow-up, significantly less AF recurrence occurred in the CB-then-RF group (22% vs 8%, HR = 0.46; 95% CI: 0.24-0.92; P = .025). Cohort designation was the only independent predictor of AF recurrence.

CONCLUSION

Alternation of energy source for repeat ablation was safe and effective, regardless the energy used first. However, patients initially treated with CB PVI undergoing repeat ablation with RF current had less AF recurrence at long-term follow-up as compared with those originally treated by RF ablation receiving a CB repeat ablation.

Ablation of persistent atrial fibrillation: Challenges and solutions

Catheter ablation is commonly used for treatment of persistent atrial fibrillation (AF). Pulmonary vein isolation (PVI) is still the cornerstone for the procedure, however, outcomes are consistently lower compared to paroxysmal AF. It is hypothesized that it could be due to lack of durable lesions or the presence of non-PV targets that remain after PVI. Numerous advances in ablation catheter technologies and mapping systems may potentially achieve lower recurrence rates in the future. Ongoing research is required to discover the best technique for persistent AF ablation. The purpose of this review is to describe the new, developing technologies that may improve the outcome of this procedure in the persistent AF population.

Temperature drop in thawing phase reflects sufficient ice formation and better outcome of pulmonary vein isolation using second-generation cryoballoon

BACKGROUND

Few reports exist regarding the details of ice formation on second-generation cryoballoon (CB) surface during pulmonary vein isolation (PVI). We propose a new parameter "temperature drop" in thawing phase for predicting sufficient ice formation and CB-PVI outcome.

METHODS

Consecutive 106 patients who underwent successful CB-PVI for atrial fibrillation (AF) were analyzed. We defined "temperature drop" as a temperature drop of more than 3 °C just after CB catheter bending. We compared the previously known parameters predicting durable PVI between PVs with or without temperature drop. Then, we compared the PVI outcome among three groups: group 1 with temperature drop in all PVs, group 2 with temperature drop in 1-3 PVs, and group 3 without temperature drop in any PV.

RESULTS

Temperature drop was present in 206 out of 424 isolated PVs. In those, PV occlusion score was significantly higher (3.7 ± 0.5 vs. 3.5 ± 0.6, P <0.001), and thawing time was significantly longer (55 ± 20 vs. 46 ± 21 s, P < 0.001) in PVs with temperature drop than those without. With a mean follow up period of 376 ± 217 days, Kaplan-Meier survival analysis revealed that no patients in group 1 experienced AF recurrence, 14 out of 86 patients (16%) experienced AF recurrence in group 2, and 5 out of 10 (50%) patients experienced AF recurrence in group 3 (Log-Rank P = 0.003).

CONCLUSION

The temperature drop in thawing phase might reflect the state of ice formation and can be used to predict clinical outcome after CB-PVI.