Impact of ablation duration on rhythm outcome after concomitant maze procedure using cryoablation in patients with persistent atrial fibrillation

BACKGROUND: The aim of this study was to evaluate the impact of ablation duration during a maze procedure using a nitrous oxide-based cryosurgical system. METHODS: From May 2001 to December 2006, 256 consecutive patients who underwent a concomitant maze procedure using nitrous oxide-based cryoablation for chronic atrial fibrillation (AF) during cardiac surgery were enrolled. The ablation duration for each lesion was between 120 s at −60 °C in 140 patients (control group) and 160 s in 116 patients (long duration group). RESULTS: One in-hospital death occurred, and a permanent pacemaker was implanted in one patient (0.4%). At discharge, absence of AF was noted in 84.5% of the long duration group and in 87.1% of the control group. During follow up, patients in the long duration group achieved and maintained the absence of AF at a higher rate than the control patients (96% vs. 84% at 24 months, respectively: P = 0.008). Multivariable analysis identified long AF duration as the only independent predictor of AF recurrence. At late follow up, left atrial mechanical activity was less frequent in the control group than in the long duration group. The mean left atrial volume index was lower in the long duration group than in the control group. CONCLUSION: The modified cryomaze procedure is safe and effective. Ablation time plays an important role in achieving and maintaining the absence of AF. Long cryoablation duration is recommended for optimal cryomaze results.