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.