3.2 Incidence of PFM with MI pseudo-block
Despite the confirmation of MI block with the aforementioned pacing maneuvers, 5 patients presented with PMF. In 3 of these patients, PMF was detected during the MI ablation procedure, while 2 patients had recurrence at 3 and 6 months after the MI ablation procedure, and the diagnosis of PMF was made during the redo procedure, while pacing maneuvers were false-positive for MI block before any ablation attempt (Figure 2 ). In all 5 patients the detailed mapping showed a MI isthmus breakthrough with slow conduction along a narrow channel (Figure 3 , Videos 1-4 ). The endocardial ablation at this area restored the completeness of the MI line in all these patients. The complete and bidirectional block of the MI was re-evaluated by pacing maneuvers and careful endocardial and epicardial mapping in the boundaries of the ablation line. In addition, after programmed atrial stimulation, PMF was no longer inducible.