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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.

Aims Pulmonary vein isolation (PVI) often is not sufficient in patients (pts) with persistent atrial fibrillation (AF). Substrate modification (SM) by catheter ablation (CA) of low-voltage zones (LVZ) has yielded favourable results, but those studies were performed before the introduction of contact force (CF) sensing technology. Surgical ablation (SA) studies support the hypothesis that empiric bi-atrial linear ablation (Cox Maze IV procedure) is able to improve success, but there is less data on outcome of patients undergoing left atrial (LA) linear lesions alone. In current guidelines, both CA and SA have Class IIa indication in pts with persistent AF. In this single-centre retrospective study, we analysed the long-term outcomes of CA and SA in pts with persistent AF. Methods and results In the CA group (Figure 1), pts underwent PVI and additional SM in the presence of LVZ (roof line and supero-septal line) using TactiCath™ or SmartTouch™ ablation catheters aiming at contact values ≥10 g 400 g/s. Ablation was performed in a temperature-controlled fashion with energy of 30 W except at the posterior wall (20–25 W). In the SA group (Figure 2), pts underwent ablation procedure (creation of a pure LA endocardial lesion set consistent with the Cox Maze IV) performed by a right mini-thoracotomy approach using the Atricure™ cryoablation probe, a left atrial appendage (LAA) epicardial exclusion using the Atriclip™ system, and mitral valve repair in the presence of severe mitral valve regurgitation. No right atrial lesions were created. 196 pts were included. 120 pts underwent CA [median age: 65 (58–72) years, median LA volume index (LAVI): 66 (56–75) ml/m2], in pts with LVZs PVI + SM was performed [bidirectional block of lines in 100%]. 76 pts underwent SA [median age: 64 (58–74) years, median LAVI 90 (78–103) ml/m2], in 42 pts a mitral valve repair was performed. At 24 months (figure), 89% and 68% of pts were free of AF in the SA and CA group, respectively, mainly without antiarrhythmic drugs (92% SA group and 89% CA group). Conclusions In patients with persistent AF, SA performed by a right mini-thoracotomy approach with linear lesions limited to LA leads to excellent 2-year freedom from AF despite significantly larger LAVI compared with the CA group. LAA epicardial exclusion likely contributed to surgical efficacy by eliminating the LAA as trigger/driver.