INTRODUCTION
Atrial fibrillation (AF) is associated with all-cause death (especially cardiovascular death), stroke, hospitalizations, low quality of life, left ventricular dysfunction and heart failure, and cognitive decline/vascular dementia 1; hence, the management of AF is important, and catheter ablation is an effective treatment. In 1998, Haissaguerre found that 94% of the ectopic beats that led to AF were in the pulmonary vein (PV) 2, and pulmonary vein isolation (PVI) has become an established treatment for AF. However, several recent studies have revealed approximately 10–20% of AF originate from non-PV foci 3-6, and the frequency of a superior vena cava (SVC) origin is the highest 4. This is a major cause of reoperation. Furthermore, catheter ablation is an invasive procedure; therefore, the elimination of AF in a single procedure is desirable. However, SVC isolation is associated with 2.1% risk of phrenic nerve injury 7 and 4.5% risk of sinus node injury 8 hence, performing SVC isolation routinely in patients with AF is not recommended.
A previous seminal study reported that the effective refractory period (ERP) in patients with AF was shorter than that in patients without AF (185±71 vs. 282±45 ms, P <0.001) 9. This study also suggested that shorter ERPs played a major role in the development of AF. Another seminal study reported that a large dispersion of the ERP within the PVs and at the PV-left atrium (LA) junction may form a reentrant substrate and play an important role in the maintenance of AF 10.
Although the frequency of an SVC origin was the highest among non-PV foci for AF, the characteristics of the ERP in the SVC (SVC-ERP) were unclear. The purpose of this study was to elucidate the relationship between the SVC-ERP and the inducibility of AF after PVI.