The biatrial substrate properties in different types of paroxysmal atrial fibrillation

Background: The biatrial substrate properties in patients with paroxysmal atrial fibrillation (AF) originating from the pulmonary veins (PVs) and superior vena cava (SVC) are not available. Objective: The purpose of this study is to characterize the differences of biatrial substrate properties in patients with different types of AF. Methods: A total of 36 patients with paroxysmal AF originating from the PV (PV-AF) and 9 patients with paroxysmal AF initiating from the SVC (SVC-AF) were included. Regional electrogram voltage, conduction velocity (CV), and spectral analysis to identify the AF nest were performed to characterize the biatrial, PVs, and SVC substrate. Results: In the left atrial (LA) body, the bipolar voltage, total activation time, CV, and dominant frequency (DF) were similar between the PV-AF and SVC-AF. However, in the PV regions, the electrogram voltage, CV, and DF were decreased in the PV-AF. The proportions of AF nest in the LA body (72.2% vs. 22.2%, P = .008) and PV regions (100% vs. 22.2%, P <.001) were higher in PV-AF compared with SVC-AF, respectively. On the other hand, lower bipolar voltage, longer total activation time, and slower CV of RA body were recognized in the SVC-AF as compared with the PV-AF. In the SVC, lower bipolar voltage, slower CV, higher DF, and higher proportions of AF nest in SVC (16.7% vs. 66.7%, P = .002) were identified in SVC-AF. Conclusion: These most-remodeled substrates in different types of paroxysmal AF indicated the importance of the atrial substrate in the vicinity of the arrhythmogenic thoracic veins. Crown