Lessons from dissociated pulmonary vein potentials: entry block implies exit block

Prior reports using pacing manoeuvres, demonstrated an up to 42 prevalence of residual pulmonary vein to left atrium (PVLA) exit conduction after apparent LAPV entry block. We aimed to determine in a two-centre study the prevalence of residual PVLA exit conduction in the presence of unambiguously proven entry block and without pacing manoeuvres. Of 378 patients, 132 (35%) exhibited spontaneous pulmonary vein (PV) potentials following circumferential PV isolation guided by three-dimensional mapping and a circular mapping catheter. Pulmonary vein automaticity was regarded as unambiguous proof of LAPV entry block. We determined the prevalence of spontaneous exit conduction of the spontaneous PV potentials toward the LA. Pulmonary vein automaticity was observed in 171 PVs: 61 right superior PV, 33 right inferior PV, 47 left superior PV, and 30 left inferior PV. Cycle length of the PV automaticity was 1000 ms in all cases. Spontaneous PVLA exit conduction was observed in one of 171 PVs (0.6). In a subset of 69 PVs, pacing from within the PV invariably confirmed PVLA exit block. Unidirectional block at the LAPV junction is unusual (0.6). This observation is supportive of LAPV entry block as a sufficient electrophysiological endpoint for PV isolation.