Individualized or fixed approach to pulmonary vein isolation utilizing the fourth-generation cryoballoon in patients with paroxysmal atrial fibrillation: the randomized INDI-FREEZE trial

Christian Hendrik Heeger*, Sorin Stefan Popescu, Roza Saraei, Bettina Kirstein, Sascha Hatahet, Omar Samara, Anna Traub, Marcel Fehe, Gabriele D'Ambrosio, Ahmad Keelani, Michael Schlüter, Charlotte Eitel, Julia Vogler, Karl Heinz Kuck, Roland Richard Tilz*

*Corresponding author for this work
6 Citations (Scopus)


Aims: Cryoballoon (CB) based pulmonary vein isolation (PVI) is a widely used technique for treatment of atrial fibrillation (AF); however the ideal energy dosing has not yet been standardized. This was a single-centre randomized clinical trial aiming at assessing the safety, acute efficacy, and clinical outcome of an individualized vs. a fixed CB ablation protocol using the fourth-generation CB (CB4) guided by pulmonary vein (PV) potential recordings and CB temperature. Methods and results: Patients were randomized in a 1:1 fashion to two different dosing protocols: INDI-FREEZE group (individualized protocol): freeze-cycle duration of time to effect plus 90 s or interruption of the freeze-cycle and repositioning CB if a CB temperature of -30°C was not within 40 s. Control group (fixed protocol): freeze-cycle duration of 180 s. No-bonus freeze-cycle was applied in either patient group. The primary endpoint was freedom from atrial tachyarrhythmia at 12 months. Secondary end points included procedural parameters and complications. A total of 100 patients with paroxysmal AF were prospectively enrolled. No difference was seen in the primary endpoint [INDI-FREEZE group: 38/47 (81%) vs. control group: 40/47, (85%), P = 0.583]. The total freezing time was significantly shorter in the INDI-FREEZE group (157 ± 56 s vs. 212 ± 83 s, P < 0.001), while procedure duration (57.9 ± 17.9 min vs. 63.2 ± 20.2 min, P = 0.172) was similar. No differences were seen in the minimum CB and oesophageal temperatures as well as in periprocedural complications. Conclusion: Compared to the fixed protocol, the individualized approach provides a similar safety profile and clinical outcome, while reducing the total freezing time.

Original languageEnglish
Issue number6
Pages (from-to)921-927
Number of pages7
Publication statusPublished - 01.06.2022

Research Areas and Centers

  • Centers: Cardiological Center Luebeck (UHZL)

DFG Research Classification Scheme

  • 205-12 Cardiology, Angiology

Cite this