New individualized strategy instructs cryoballoon energy ablation

New individualized strategy instructs cryoballoon energy ablation

Wei-Dong Lin, Xian-Hong Fang, Yu-Mei Xue, Hong-Tao Liao

Department of Cardiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China

Correspondence to: Hong-Tao Liao, MD. Department of Cardiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China. Email:

Provenance: This is an invited Editorial commissioned by the Section Editor Fang-Zhou Liu (Guangdong Cardiovascular Institute, Guangdong, China).

Comment on: Chun KR, Stich M, Fürnkranz A, et al. Individualized cryoballoon energy pulmonary vein isolation guided by real-time pulmonary vein recordings, the randomized ICE-T trial. Heart Rhythm 2017;14:495-500.

Submitted Mar 16, 2017. Accepted for publication Dec 11, 2017.

doi: 10.21037/jtd.2017.12.99

Atrial fibrillation (AF), as one of the most common cardiac arrhythmias, is associated with significant morbidity and mortality (1). Pulmonary vein isolation (PVI) remains the cornerstone treatment for paroxysmal atrial fibrillation (PAF) (2). The second generation of cryoballoon (CB2, Arctic Front Advance, Medtronic, Inc., MN, USA) has proven high success rate in PVI for patients with PAF (3,4). The “Fire and Ice trial” confirms cryoballoon ablation is equivalent to radiofrequency ablation with respect to efficacy for the treatment of patients with PAF (5).

Currently 2 bonus freeze cycles were performed at each target PV to enhance the lesion depth during cryoballoon procedure (6). However, previous study presented that 2 bonus freeze cycles were associated with a higher complication rate but similar success rate when compared to 1 freeze–thaw cycle following CB PVI (7). Another study demonstrated that a single 3-minute freeze was equally effective at 1-year follow-up (8). Further studies were necessary to determine the ideal number of bonus application. In order to record left atrium–pulmonary vein disconnection during cryoballoon procedure, an 8-pole circular mapping catheter (Achieve™, Medtronic Inc., MN, USA) is advanced through the lumen of the CB catheter. Faster time to pulmonary vein isolation (TTI) recorded by AchieveTM was an independent predictor for durable PVI (9). It seems that TTI could instruct the CB2 ablation time and optimize the CB2 dosing strategy. On this purpose, K.R. Julian Chun launched the “ICE–T” Trial (Individualized Cryoballoon Energy pulmonary vein isolation guided by real Time pulmonary vein recordings) (10).

The “ICE–T” Trial was the first randomized study to investigate the safety and efficacy of individualized PVI guided by real-time PV recordings. A total number of 100 patients were randomized into 2 groups: ICE-T group (if TTI <75 s then no bonus freeze) and Control group (acute PVI followed by one bonus freeze). PVI was successfully performed in all patients and 79% of PVs TTI were visualized. The Primary endpoint was not different between 2 groups, but procedure and fluoroscopy time were significantly shorter in the ICE-T group. What’s more, the control group has higher complication rate. A mean TTI >43 s was an independent predictor of recurrent atrial tachyarrhythmia (ATa) when using multivariate analysis.

The “ICE–T” Trial demonstrated the importance of real-time recordings during CB2 ablation and the ICE-T CB2 ablation strategy allowed a faster PAF ablation with no influence of PVI rate. No significant difference was observed on complications between ICE-T group and control group. However, the ICE-T group seemed to have less complication. It is encouraged that the present study firstly confirmed the feasibility of individualized dosing strategy based on TTI.

Pulmonary vein potential (PVP) visualization was prerequisite to develop strategies based on TTI. However, the rate of PVP visualization might be varied among centers. Several studies had suggested that real-time PVI assessment during cryoablation was only observed in <50% of patients (11) because the AchieveTM catheter was remote from PV antrum to offer catheter stability during CB ablation. What’s more, shaft extended 1 cm beyond the balloon tip creating a distance between the AchieveTM catheter and ablation site. Medtronic developed the third-generation Cryoballoon Advance Short-tip (Cryoballoon Advance Short Tip; Medtronic, Minnesota, USA) (CB-ST) to increase the detection rate of TTI. Giacomo Mugnai’s study showed that the rate of visualization of real-time recordings was significantly higher during third-generation CB-ST ablation if compared to the CB2 device. Real-time recordings could be visualized in about 85.7% of PVs with CB-ST (12).

Multivariate analysis illustrated a mean TTI >43 s as an independent predictor of recurrent ATa in “ICE–T” Trial. However, the variety of CB temperatures during ablation were not collected, the relation between CB temperature and recurrent ATa remained unknown in this trail. Giuseppe Cicon’s research indicated that achievement of −40 °C within 60 s could independently predict durable PVI (12). Furthermore, an increased time taken for the balloon to warm following ablation was associated with durability of PVI (13). The result might be more meaningful if the trial adjusted CB temperatures variety.

In general, the “ICE–T” Trial suggested that ICE-T CB ablation strategy made CB2 ablation faster without impacting the clinical outcome. TTI as a predictor of recurrent ATa might be more persuasive if the trial adjusted the CB temperatures variety. Most importantly, TTI was based on PVP visualization during CB2 ablation, how to guarantee the relatively high PVP visualization rate needed further investigations to determine.




Conflicts of Interest: The authors have no conflicts of interest to declare.


  1. January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2014;64:e1-76. [Crossref] [PubMed]
  2. Haïssaguerre M, Jaïs P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659-66. [Crossref] [PubMed]
  3. Metzner A, Reissmann B, Rausch P, et al. One-year clinical outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon. Circ Arrhythm Electrophysiol 2014;7:288-92. [Crossref] [PubMed]
  4. Metzner A, Heeger CH, Wohlmuth P, et al. Two-year outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon: lessons from the bonus freeze protocol. Clin Res Cardiol 2016;105:72-8. [Crossref] [PubMed]
  5. Kuck K, Brugada J, Albenque J. Cryoballoon or Radiofrequency Ablation for Atrial Fibrillation. N Engl J Med 2016;375:1100-1. [PubMed]
  6. Gage AA, Baust JM, Baust JG. Experimental cryosurgery investigations in vivo. Cryobiology 2009;59:229-43. [Crossref] [PubMed]
  7. Chun KR, Fürnkranz A, Köster I, et al. Two versus one repeat freeze-thaw cycle(s) after cryoballoon pulmonary vein isolation: the alster extra pilot study. J Cardiovasc Electrophysiol 2012;23:814-9. [Crossref] [PubMed]
  8. Ciconte G, Sieira-Moret J, Hacioglu E, et al. Single 3-Minute versus Double 4-Minute Freeze Strategy for Second-Generation Cryoballoon Ablation: A Single-Center Experience. J Cardiovasc Electrophysiol 2016;27:796-803. [Crossref] [PubMed]
  9. Ciconte G, Mugnai G, Sieira J, et al. On the Quest for the Best Freeze: Predictors of Late Pulmonary Vein Reconnections After Second-Generation Cryoballoon Ablation. Circ Arrhythm Electrophysiol 2015;8:1359-65. [PubMed]
  10. Chun KR, Stich M, Fürnkranz A, et al. Individualized cryoballoon energy pulmonary vein isolation guided by real-time pulmonary vein recordings, the randomized ICE-T trial. Heart Rhythm 2017;14:495-500. [Crossref] [PubMed]
  11. Boveda S, Providência R, Albenque JP, et al. Real-time assessment of pulmonary vein disconnection during cryoablation of atrial fibrillation: can it be 'achieved' in almost all cases? Europace 2014;16:826-33. [Crossref] [PubMed]
  12. Mugnai G, de Asmundis C, Hünük B, et al. Improved visualisation of real-time recordings during third generation cryoballoon ablation: a comparison between the novel short-tip and the second generation device. J Interv Card Electrophysiol 2016;46:307-14. [Crossref] [PubMed]
  13. Ghosh J, Martin A, Keech AC, et al. Balloon warming time is the strongest predictor of late pulmonary vein electrical reconnection following cryoballoon ablation for atrial fibrillation. Heart Rhythm 2013;10:1311-7. [Crossref] [PubMed]
Cite this article as: Lin WD, Fang XH, Xue YM, Liao HT. New individualized strategy instructs cryoballoon energy ablation. J Thorac Dis 2018;10(1):83-84. doi: 10.21037/jtd.2017.12.99