Impact of electrical connections between ipsilateral pulmonary veins on the second-generation cryoballoon ablation procedure

Differential gap location after radiofrequency versus cryoballoon pulmonary vein isolation: Insights from a randomized trial with protocol-mandated repeat procedure

INTRODUCTION

Reconnections to pulmonary vein (PV) triggers of atrial fibrillation (AF) are the primary cause of AF recurrence after PV isolation (PVI) with radiofrequency (RF) or cryoballoon catheter ablation (CRYO), but method-specific contributions to PV reconduction pattern and conductive gap location are incompletely understood.

METHODS

The objective of this radiofrequency versus cryoballoon catheter ablation for paroxysmal atrial fibrillation substudy was to determine procedure-specific patterns of PV reconduction in a randomized population with protocol-mandated repeat procedures, irrespective of AF recurrence. Each PV was assessed in turn and PV reconnection sites were identified by high-density electroanatomical mapping and locating the earliest activation site. Gap locations were verified by PV re-isolation.

RESULTS

In 98 patients, 81% versus 76% previously isolated PVs remained isolated after CRYO versus RF (risk ratio [RR]: 1.06; 95% confidence interval [CI]: 0.96-1.18; p = .28). There were no significant differences for any PV: left superior PV: 90% versus 80%; left inferior PV: 80% versus 78%; right superior PV: 81% versus 80%, and right inferior PV: 76% versus 73%. For each reconnected PV, 34% of ipsilateral PVs were also reconnected after CRYO compared with 64% after RF (RR: 0.54; 95% CI: 0.32-0.90; p = .01). After RF, gaps were clustered by the carina and adjacent segments, whereas they were more heterogeneously distributed after CRYO.

CONCLUSION

Although RF and CRYO produce similar proportions of durably isolated PVs, gap locations appear to develop in procedure-specific patterns. After RF, ipsilateral PV reconduction is more frequent and gap sites cluster by the carina, suggesting that this region should be selectively ablated for more durable PVI.

A novel alternating second-generation cryoballoon or contact-force guided radiofrequency catheter ablation strategy for redo-ablation in patients with recurrent atrial fibrillation: a single-center experience

BACKGROUND

Pulmonary vein (PV) reconnection after radiofrequency (RFC) or cryoballoon (CB) pulmonary vein isolation (PVI) is common.

METHOD

We report a single-center experience of 156 patients who underwent a redo procedure-ablation strategy for recurrent atrial fibrillation (AF) in a reverse sequence after a failed index RFC or CB PVI.

RESULTS

A total of 60 patients after index CB PVI underwent RFC-redo ablation (CB-RFC redo), and 96 patients after index RFC PVI underwent CB-redo ablation (RFC-CB redo). During the redo procedure, the proportion of patients with PV reconnection was lower after index CB PVI procedure compared with the proportion of patients after index RFC PVI (88.3% versus 98.9%, p = 0.01). Additionally, a mean number of 1.50 ± 0.8 PVs/patient were reconnected after index CB PVI, compared with 3.36 ± 0.9 PVs/patient after index RFC PVI (p = 0.001). Patients after index RFC PVI frequently presented with ≥ 3 reconnected PVs, compared with index CB PVI (70.8% vs 10%, p < 0.001). At a 2-year follow-up, 43 patients (27.6%) developed recurrence after redo ablation, with a similar AF-free outcome (CB-RFC redo:73.3% vs RFC-CB redo: 71.9%, p = 0.873). In the multivariate analysis, persistent AF (HR = 2.107, 95% CI: 1.085-4.091, p = 0.028) and early AF recurrence after the initial ablation (HR = 2.431, 95% CI: 1.279-4.618, p = 0.007) were independent predictors of AF recurrence.

CONCLUSIONS

The extent and distribution of PV reconnections were different after index RFC and CB PVI procedures. Alternating CB or RFC ablation technique strategy is effective with a similar long-term outcome, and it may be an appropriate option for repeated AF ablation.

The impact of electrical connections between left ipsilateral pulmonary veins on the time-to-isolation values in cryoballoon ablation

BACKGROUND

The time-to-isolation (TTI) may be a physiological predictor of durable isolations, and TTI-guided dosing strategies are widely performed in cryoballoon ablation. We sought to investigate the impact of the order of targeting the pulmonary veins (PVs) on the TTI values of left ipsilateral PVs.

METHODS

This study included 144 atrial fibrillation patients who underwent PV isolations using 28-mm fourth-generation cryoballoons. In 101 patients, the left superior PV (LSPV) was targeted and followed by the left inferior PV (LIPV) (group 1), and the LIPV was targeted and followed by the LSPV in the remaining 43 (group 2).

RESULTS

The total LSPV and LIPV freeze durations were 193 ± 60 and 171 ± 40 s, respectively. Real-time PV isolation monitoring was capable in 137 (95.1%) LSPVs and 119 (82.6%) LIPVs and in 112 (77.8%) patients (78 in group 1 and 34 in group 2) in both LSPVs and LIPVs. Among them, the LSPV TTI was significantly longer in group 1 than that in group 2 (54.8 ± 32.1 vs. 34.1 ± 17.3 s, p < 0.0001), while the LIPV TTI was significantly shorter in group 1 than that in group 2 (23.7 ± 11.8 vs. 39.2 ± 19.4 s, p < 0.0001). The ΔTTI ((TTI in LSPV)-(TTI in LIPV)) was significantly greater in group 1 than that in group 2 (31.1 ± 31.4 vs. - 5.0 ± 25.9 s, p < 0.0001). In 5 patients (3 in group 1 and 2 in group 2), initially targeted left PVs were not isolated despite complete vein occlusions, while they were by subsequent applications at the other ipsilateral PVs.

CONCLUSIONS

In CB ablation, the order of targeting PVs highly influenced the TTI of the left PVs owing to the presence of electrical connections between left ipsilateral PVs.

Predictors of the "Crosstalk" Phenomenon During Cryoballoon Ablation in Patients with Atrial Fibrillation

Second-generation cryoballoon (CB) ablation is effective in achieving pulmonary vein (PV) isolation (PVI) in atrial fibrillation (AF) patients. The "crosstalk" (CST) phenomenon has been reported to reduce unnecessary applications during CB ablation. Nevertheless, it is unclear under what conditions the CST phenomenon occurs.To seek the predictors of the CST phenomenon during CB-guided PVI, CST phenomenon in achieving ipsilateral superior PVI during inferior PV ablation was analyzed in AF patients who underwent de novo ablation using CB. CB occlusion status and nadir balloon temperature (NT) were compared in these patients, and all ablated superior PVs were categorized into three groups according to the necessity of the touch up ablation and effectiveness of the phenomenon.Of 1082 superior PVs, 16, 40, and 1026 were classified into the CST success, CST failure, and control groups (unnecessary CST), respectively. The proportion of superior PVs ablated with complete occlusion using the CB was significantly higher in the CST success group than in the other two groups. The proportion of superior PVs ablated with NT ≤ -46°C was higher in the CST success group than in the CST failure group. The CST phenomenon was always observed if CB ablation of the superior PVs was performed with both complete occlusion and NT ≤ -46°C and was almost always ineffective if it did not meet these two criteria (sensitivity, 100%; specificity, 93%).Successful CST ablation was highly predicted if complete PV occlusion and NT ≤ -46°C during CB ablation of the superior PVs were achieved.

Improved real-time recordings using the fourth-generation cryoballoon technology-detection of dual fascicle electrograms

BACKGROUND

We aimed to analyze the rate of visualization of real-time (RT) recordings and dual fascicle electrograms in our first series of patients treated with the fourth-generation cryoballoon (CB) device.

METHODS

All consecutive patients who underwent CB ablation using the fourth-generation technology were included in the analysis. In all procedures, we used a 28-mm CB placed via a single transseptal puncture guided by intracardiac ultrasound. A 20-mm octapolar intraluminal circular catheter was used for intracardiac recordings. A single 180-s freeze strategy was employed.

RESULTS

A total of 129 patients (72.9% male, mean age 60.1 ± 10.9 years) were enrolled in the study. RT recordings were detected in 445 (86.2%) pulmonary veins (PVs). Specifically, RT recordings were visualized in 115 left superior PVs (89.2%), 107 left inferior PVs (82.9%), 118 right superior PVs (91.4%), and 105 right inferior PVs (81.3%). Dual fascicle electrograms could be observed only in patients in sinus rhythm, in 23 of 396 PVs (5.8%). They were most commonly observed in the left superior PV (8.1%), somewhat less in both inferior veins (6.1%), while this phenomenon was least frequent in the right superior PV (3.0%).

CONCLUSIONS

By using the fourth-generation CB, we report a specific pattern of isolation represented by a sequential isolation of two apparently distinct PV fascicles during a single CB freeze delivery. This phenomenon occurred in 5.8% of PV ablations. Of note, the rate of visualization of RT isolation with this novel CB was very high and could be documented in 86.2% of PVs.

Predictors of durable pulmonary vein isolation after second-generation cryoballoon ablation with a single short freeze strategy - Different criteria for the best freeze of the 4 individual PVs

BACKGROUND

Parameters predicting the second-generation cryoballoon pulmonary vein isolation (CB-PVI) durability of each individual PV have not been investigated.

OBJECTIVE

We explored the PVI durability predictors after left superior (LS), left inferior (LI), right superior (RS), and right inferior (RI) PV CB-PVI.

METHODS

Data from 101 consecutive patients who underwent repeat procedures 7.0 [4.5-10.0] months after index cryoballoon procedures with single short freeze strategies were analyzed.

RESULTS

Among 369 PVs successfully isolated by cryoballoons with mean freezing times of 207 s, 82/94 (87.2%) LSPVs, 78/93 (83.9%) LIPVs, 80/98 (81.6%) RSPVs, and 63/84 (75.0%) RIPVs were durable. In the remaining 25 PVs requiring touch-up ablation, 20 (83.3%) PVs had reconnections. In analyzing all PVs together, lower nadir balloon temperature, faster freezing speed (FS), slower thawing speed (TS), and shorter time-to-isolation were significantly associated with higher PVI durability, however, all parameters significantly differed among the 4 individual PVs (p < 0.0001). In individual analyses, for the LSPV, faster FS to -40 °C predicted higher PVI durability, but younger patients more likely had reconnections. For the LIPV, faster FS to -30 °C predicted higher PVI durability. For the RSPV, a lower nadir temperature, faster FS (to -30 and -40 °C), slower TS (to 0 and 15 °C), shorter time-to-isolation, and smaller PV diameter predicted higher PVI durability. For the RIPV, a slower TS (to 0 and 15 °C) predicted higher PVI durability.

CONCLUSIONS

The durability of the CB-PVI was high even with a single short freeze strategy. The parameters predicting the PVI durability differed among the 4 PVs, suggesting that best freeze criterion should be considered separately for each of the 4 PVs.