Cryoballoon ablation (CBA) is an established approach for rhythm management of atrial fibrillation (AF). We sought to assess balloon temperature (BT) parameters as predictors of pulmonary vein (PV) reconnection within the index procedure and AF recurrence following CBA.

BT was monitored in 119 AF patients undergoing CBA. PVs were assessed for reconnection during the procedure and patients were followed for arrhythmia recurrence.

PV reconnection was identified in 39 (8.3%) of 471 PVs. BT was significantly colder in the absence of PV reconnection (30 s: − 33.5 °C [− 36; − 30] vs − 29.5 °C [− 35; − 25.5], p = 0.001; 60 s: − 41 °C [− 44; − 37] vs − 36.5 °C [− 42; − 33.5], p < 0.001; nadir: − 47 °C [− 52; − 43] vs − 41.5 °C [− 47; − 38], p < 0.001). PV reconnection was associated with significantly longer time to reach − 15 °C and – 40 °C (14.5 s [11.5–18.5] vs 12 s [10–15.5], p = 0.023; and 75 s [40–95.5] vs 46 s [37–66.75], p = 0.005) and shorter rewarming time (5.75 s [4.75–8.5] vs 7 s [6–9], p = 0.012). ROC analysis of these procedural parameters had an AUC = 0.71 in predicting PV reconnection. AF recurrence occurred in 51 (42.8%) patients. Kaplan–Meier analysis showed better arrhythmia-free survival for patients in whom BT decreased below – 40 °C in all PVs and patients who had no early PV reconnections, compared to patients in whom BT below – 40 °C was not achieved in at least one PV (log rank = 6.3, p = 0.012) and patients who had PV reconnections (log rank = 4.1, p = 0.043).

Slower BT decline, warmer BT nadir, and faster rewarming time predict early PV reconnection. Absence of early PV reconnections and BT dropping below – 40 °C in all PVs during CBA are associated with lower rates of AF recurrence.