Background:

The optimal freeze duration in cryoballoon pulmonary vein isolation is unknown. In order to enable individualized freeze duration, TTI-based titration of cryoenergy has emerged as a favorable ablation strategy in pulmonary vein cryoablation and has shown equal efficacy in clinical studies.

Methods:

We compared rate of pulmonary vein (PV) reconnection in patients undergoing second AF ablation procedure after treatment with a TTI guided titration of freeze duration to a rate of PV reconnection in patients after treatment with a fixed ablation protocol.

We compared rate of PV reconnection in patients undergoing a second atrial fibrillation ablation after having initial pulmonary vein cryoablation with either a fixed freeze cycle length or a TTI-guided freeze cycle length.

In the fixed group, freeze cycle length was 240s followed by another 240s after acute pulmonary vein isolation. In the TTI group, freeze cycle duration was 120s if TTI was shorter than 30s and 180s if TTI was 30s to 60s. If the TTI was longer than 60s, an additional 180s bonus freeze was applied.

Second AF ablation was performed by three-dimensional mapping system and radiofrequency ablation technique.

Results:

167 consecutive patients (mean age 66,2±10,8 years, 53% female) treated with TTI-guided protocol (127 patients, 499 PVs) and fixed protocol (40 patients, 159 PVs) showed comparable reconnection rates (40,6% vs. 34,6%, p= 0.17). Reconnection rate of LSPV, RSPV and RIPV was statistically not different between both study groups. Reconnection rate was lower in LIPV treated with fixed protocol (13% vs. 31%, p= 0.029). In the TTI group 17/127 patients (15%) had durable isolation of all PV, whereas in 8/40 patients (20%) in the fixed group all PV were still isolated (p=0.31).

Mean PVI duration was significantly shorter in the TTI group (91,3±31,6 min vs. 131,2±28,7 min, p< 0.001), as well as mean cumulative freeze duration (1074s vs. 2071s, p<0.001).

Conclusion:

Overall reconnection rate was not different using a TTI-guided ablation protocol, whereas LIPV reconnection rate was lower in the fixed protocol group.