Distinctive electrophysiological properties of pulmonary veins in patients with atrial fibrillation

Background-Atrial fibrillation (AF) is frequently initiated from pulmonary veins (PVs), but little is known of the electrophysiological properties of PVs. Methods and Results-Two groups were studied: 28 patients (49+/-13 years old) with paroxysmal AF and 20 control patients (49+/-14 years old) without AF. Effective and functional refractory period and conduction time from PV to left atrium (LA) were compared in the 2 groups by use of programmed stimulation with a single extrastimulus in the PVs and LA. In the AF group, the venous effective refractory periods (ERPs) were shorter than that of the LA: 185+/-71 versus 253+/-21 ms, P<0.001, whereas in the control group, they were longer (282+/-45 versus 253+/-41 ms, P=0.009). The venous ERPs and functional refractory periods in patients with AF were also shorter than that observed in control subjects (185+/-71 versus 282+/-45 ms and 210+/-77 versus 315+/-43 ms, respectively, P<0.001), whereas LA ERPs were not significantly different. Decremental conduction in PVs was more frequent (93% versus 56%, P=0.01) and had a greater increment (102+/-65 versus 42+/-40 ms, P<0.001) in patients with AF. Finally, AF was more frequently induced when pacing was performed in PVs (22 of 90) versus LA (1 of 81) in patients with AF (P<0.001). Conclusions-The PVs of patients with AF exhibited distinctive electrophysiological properties, which were strikingly different from those of patients devoid of AF, potentially explaining their arrhythmogenicity.