Elsevier

Heart Rhythm

Volume 10, Issue 9, September 2013, Pages 1311-1317
Heart Rhythm

Balloon warming time is the strongest predictor of late pulmonary vein electrical reconnection following cryoballoon ablation for atrial fibrillation

https://doi.org/10.1016/j.hrthm.2013.06.014Get rights and content

Background

Pulmonary vein isolation by cryoballoon ablation is an accepted method of treating atrial fibrillation. Little data exist regarding factors affecting late electrical reconnection of pulmonary veins following cryoballoon ablation.

Objective

To investigate factors determining pulmonary vein reconnection in patients undergoing repeat catheter ablation for recurrent atrial fibrillation following cryoballoon ablation.

Methods

Fifty-one consecutive patients undergoing repeat catheter ablation for recurrent atrial fibrillation following initial cryoballoon ablation underwent retrospective assessment of initial cryoablation characteristics, including balloon and vein sizes, venogram occlusion score, balloon freezing time from 0 to −30°C, nadir temperature, and balloon warming time from −30 to +15°C, recorded during the initial cryoballoon procedure.

Results

Of 199 veins assessed, 91 had reconnected (1.8 per patient). Balloon warming time (odds ratio [OR] 3.21; 95% confidence interval [CI] 2.00–5.13; P < .0001), nadir temperature (OR 1.94; 95% CI 1.42–2.66; P < .0001), vein occlusion score (OR 1.74; 95% CI 1.29–2.34; P = .0003), and balloon freezing time (OR 1.58; 95% CI 1.03–2.42; P = .037) predicted pulmonary vein reconnection. On multivariate analysis, balloon warming time (OR 3.71; 95% CI 2.2–6.24; P ≤ .0001), pulmonary vein size (OR 1.63; 95% CI 1.08–2.43; P = .020), and vein occlusion score (OR 1.48; 95% CI 1.06–2.08; P = .021) remained statistically significant independent predictors of pulmonary vein reconnection. The receiver operating characteristic for the multivariate model yielded an area under the curve of 0.82.

Conclusions

Balloon warming time, vein occlusion score, and pulmonary vein size predict pulmonary vein reconnection. Balloon warming time was the most important predictive factor, and the manipulation of balloon warming may be a novel therapeutic strategy for improving outcomes of cryoballoon ablation for atrial fibrillation.

Introduction

Pulmonary vein isolation (PVI) is an important component of atrial fibrillation (AF) ablation. Cryoballoon ablation is a standard method of achieving PVI.1 Acute PVI rates using cryoablation are in the range of 90%–100%,2, 3, 4, 5 and factors determining acute PVI using cryoballoon ablation have been investigated extensively.5, 6, 7, 8, 9, 10 Recurrence of AF following ablation is nearly always associated with pulmonary vein (PV) electrical reconnection.11, 12 However, limited data exist regarding the factors determining PV reconnection following cryoballoon ablation. We aimed to investigate factors determining PV reconnection in patients undergoing repeat catheter ablation for recurrent AF.

Section snippets

Methods

One hundred ninety-six patients underwent cryoballoon ablation for AF between April 2009 and November 2012 (derivation cohort). Characteristics of the initial ablation were systematically recorded. Of these patients, 51 underwent repeat electrophysiology studies after developing recurrent symptomatic AF. These consecutive patients constitute the study cohort. PVs were categorized as either persistently isolated or electrically reconnected. Characteristics of isolated and reconnected veins were

Results

Fifty-one patients underwent reassessment for recurrent symptomatic AF at a mean of 9 ± 5 months following the initial procedure. Of a total of 207 veins, 199 were treated by cryoablation alone and had data eligible for analysis. Of these, 91 had reconnected electrically to the left atrium (mean number of veins reconnected per patient = 1.8). All eligible veins remained isolated in 7 of 51 (14%) patients; a single vein had reconnected in 14 of 51 (27%) patients; 2 veins had reconnected in 16 of

Discussion

The most important novel finding from this study is that balloon warming time was the best predictor of PV reconnection. We found that an increased time taken for the balloon to warm following ablation was associated with an increased durability of PVI. There are at least 2 potential explanations for this finding. First, the balloon warming time is a simple measure of an effective cryoablation. Although the balloon temperature is not an accurate measure of absolute tissue temperature, it

Conclusions

Of the variables studied, we identified balloon warming time, vein occlusion score, and PV size as being independent predictors of late PV reconnection. Warming time appeared to be the most important single factor in predicting PV reconnection. Techniques that improve balloon/tissue contact and lengthening the warming time may result in an increased long-term success of cryoballoon ablation.

References (20)

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    It is important to point out that at TTI, the cells have not necessarily reached a lethal freeze temperature, but the disappearance of PV potentials is indicative of circumferential cold propagation through the tissue, which has been studied as an indicator of lesion durability. A variety of parameters (eg, balloon-to-PV occlusion scores, balloon temperatures at various points during the freeze, freeze duration, and TTI) have been evaluated as intraprocedural predictors of durable PVI.20,21 In an analysis of PV reconnection in patients who underwent a repeat procedure after index cryoballoon PVI, neither the number nor the duration of freezes predicted PV reconnection.

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Dr Ghosh is partly funded by the Friends of the Mater Foundation, North Sydney. Dr Singarayar is on the medical advisory committees for St Jude Medical and Medtronic. Dr McGuire has received honoraria from St Jude Medical and Medtronic for lectures.

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