3.4 Arrhythmia recurrences and details of the redo procedures
After the index procedure which included MI ablation, a redo procedure was required in 9 patients. The AF/AT free survival rate, in a mean follow-up period of 22.2±8.1 months, was 66.7% (48/72 patients) and 77.8% (56/72 patients) after the index MI ablation procedure and the supplementary redo procedure, respectively. Particularly, in patients with AT, the event-free survival rate was 71.9% (23/32 patients) and 87.5% (28/32 patients) after the index and the redo procedure, respectively, while patients with AF had 62.5% (25/40 patients) and 70% (28/40 patients) event-free survival rate after the index and the redo procedure, respectively. Patients with AT appeared to have a significantly better prognosis in maintaining SR after MI ablation than patients with AF (log-rank, P=0.0466) (Figure 7 ). However, 87.5% of patients with AT had previously undergone LA ablation compared to 22.5% of patients with AF. Of the 4 patients who had unsuccessful MI ablation at the initial procedure, one who relapsed with PMF has undergone re-ablation with successful completion of MI and since then he is in SR, while of the other three, two had AF recurrence and underwent rate control therapy and one remained in SR. Among patients with PMF and MI pseudo-block, only one recurred with a brief episode of paroxysmal AF 18 months after the index MI ablation procedure.
After the successful MI ablation, 9 patients underwent a redo procedure due to AT/AF recurrence. In 8 / 9 (88.9%) the pacing proof of MI block was maintained. In one of the 9 patients the MI conduction had overtly recurred, and in 2 patients MI pseudo-block was confirmed, as the pacing criteria of MI block were fulfilled in parallel with the occurrence of PMF. The PMF was successfully treated by ablating the gap in MI.
Thirty-seven patients who underwent MI ablation had previous AF ablation (33 one procedure, and 4 two procedures, 1.1 procedures / patient). During the MI ablation procedure, PV reconnection was found in 27/37 (73%) patients with at least 1 PV reconnected and in 66/148 (44.6%) of the re-evaluated PVs.