Prolonged atrial effective refractory periods in atrial fibrillation patients associated with structural heart disease or sinus node dysfunction compared with lone atrial fibrillation.

Backgrounds: Atrial fibrillation (AF) is commonly associated with structural heart disease (SHD) or sinus node dysfunction (SND). We hypothesized that regional atrial effective refractory period (ERP) is different in patients with SHD/SND from lone AF.

Methods: We included 648 patients with AF (age, 56.0 ± 11.0 years; male, 77.3%; paroxysmal AF [PAF], 67.9%; persistent AF [PeAF], 32.1%) who underwent radiofrequency catheter ablation (RFCA), and compared the clinical characteristics in patients with SHD (n = 132) versus without SHD (n = 516) and those with SND (n = 74) versus without SND (n = 574). ERPs were measured at the high and low right atrium, proximal, and distal coronary sinus.

Results: (1) Patients with SHD had older age (P < 0.001), greater left atrial (LA) volume (P < 0.001), LA pressure (P = 0.002), and plasma proatrial natriuretic peptide (P = 0.005) than patients without SHD. (2) Patients with SND were older (P = 0.004), more likely female (P = 0.004), and had lower body weight (P < 0.001) and higher E/E' (P < 0.001) than those without SND. (3) The mean atrial ERP was significantly shorter in patients with PeAF than those with PAF (P < 0.001). The mean ERP was significantly longer in patients with AF with SHD/SND than those with lone AF (P = 0.006). (4) The clinical outcomes of RFCA were not significantly different between SHD/SND and lone AF for 14.8 ± 8.5 months of follow-up period.

Conclusion: The mean atrial ERP was shorter in patients with PeAF than those with PAF due to electrical remodeling. In contrast, AF patients with SHD/SND showed a more prolonged mean atrial ERP than those with lone AF, associated with LA enlargement or left ventricular diastolic dysfunction.