Introduction: Although slow automatic pulmonary vein (PV) activity dissociated from the atrium after achievement of PV isolation in patients with atrial fibrillation (AF) has been reported, little is known about dissociated PV tachycardia. The aim of this study was to investigate the inducibility and the mechanism of sustained PV tachycardia (SPVT).
Methods and results: One hundred thirty-two patients with drug-refractory paroxysmal AF underwent PV isolation by radiofrequency catheter ablation. Programmed stimulation was performed in 269 PVs of 110 of these patients after achievement of PV isolation. In 7 PVs (2.6%; left superior PV: n = 2, right superior PV: n = 4, right inferior PV: n = 1) of 7 (6.4%) of 110 patients, 18 SPVTs were induced. Fifteen regular SPVTs (mean cycle length 152 +/- 34 msec) were induced in 6 of 7 PVs, and 3 irregular SPVTs (cycle length range: 94-276 msec) were induced in 3 of 7 PVs. In 2 PVs, both regular and irregular SPVTs were induced. SPVT was terminated by burst pacing in 4 PVs, and entrainment was observed during regular SPVT in 5 PVs. Slow PV automatic activity dissociated from the atrium and decremental conduction properties were shown in all 7 PVs. The shortest pacing cycle length with 1:1 capture was < or =150 msec in 6 of 7 PVs.
Conclusion: Reentrant tachycardia can occur in some isolated PVs with both decremental conduction properties and short refractory periods, which suggests that reentry may be one of the mechanisms of PV arrhythmogenicity.