BACKGROUND The ideal energy dosing remains unclear in second-generation cryoballoon (CB) pulmonary vein isolation (PVI). We aimed to investigate the effect of an individualized dosing strategy based on time to PVI (TTI). OBJECTIVE The purpose of this study was to prospectively investigate the safety and efficacy of individualized PVI using the second-generation CB guided by real-time pulmonary vein recordings. METHODS Two groups were prospectively randomized: ICE-T group: if TTI < 75 seconds, then no bonus freeze; and control group: acute PVI followed by 1 empiric bonus freeze. Freeze duration was set to 240 seconds. The primary end point was single procedure sinus rhythm after 12 months (blanking period 3 months). Secondary end points included procedural data, complications, and biomarker release. RESULTS In total, 100 patients with paroxysmal atrial fibrillation were randomized. The primary end point was not different (88% vs 82%). Procedure and fluoroscopy times were significantly shorter in the ICE-T group (70 +/- 20 minutes vs 89 +/- 21 minutes; P43 seconds as the only independent predictor of recurrent atrial tachyarrhythmia. CONCLUSION The individualized CB PVI strategy allows faster atrial fibrillation ablation without affecting the favorable clinical outcome. A short TTI appears to predict freedom from recurrent atrial tachyarrhythmia.