The Timing and Frequency of PulmonaryVeins Unexcitability Relative to Completion of a WideArea Circumferential Ablation Line for Pulmonary Vein Isolation.

Abstract

This study sought to assess loss of pulmonary vein (PV) excitability to pacing relative to the development of entrance block and the anatomic completion of the circumferential radiofrequency ablation (RFA)line. During encircling RFA for PV isolation (PVI), entrance block develops before anatomic completion of encirclement (early) in some patients. We hypothesized that early entrance block may be associated with loss of PV excitability to pacing. In 30 patients undergoing PV isolation (age 61 ± 10 years, 21 men), excitability to pacing was assessed atpredefined PV sites when entrance block developed and after completion of the RFA line. Of 60 PV pairs, 37 developed entrance block early, with a gap≥10 mm in the RFA line. In only 35% of PV pairs in this subgroup, both PV sleeves captured, and all of the capturing PV pairs showed exit block (no conduction from PVtoatrium) despite the presence of an excitable gap. In the remaining 23 PV pairs, entrance block did not occur untilencircling RFA was anatomically complete. In 83% of these PV pairs, both sleeves captured with exit block (p<0.001compared with early block PVs). The majority of PV pairs develops entrance and exit block before complete anatomic encircling by RFAlesions. Early entrance block is frequently associated with loss of PV sleeve excitability, consistent with a spreading waveof injury or edema rather than a permanent conduction barrier. This may help to explain the significant rate of PV conduction recovery associated with the acute endpoints of entrance and exit block.