Differences in pre-existing atrial substrate in bicuspid and tricuspid aortic valve patients and the development of early post-operative atrial fibrillation

Abstract Background Postoperative atrial fibrillation (PoAF) is one of the most common complications after cardiac surgery. Patients with a congenital bicuspid aortic valve (BAV) often require aortic valve surgery at a younger age than those with a tricuspid aortic valve (TAV). Previous research showed that the pre-existing atrial substrate plays a critical role in development of PoAF. However, the exact differences in pre-existing substrates between BAV and TAV in the pathophysiology of PoAF are still unknown. Purpose To investigate differences in pre-existing substrates in BAV and TAV patients and development of early, (≤5 days after surgery) de novo PoAF. Methods Adult patients without a history of atrial fibrillation with either a BAV (N=49) or TAV (N=53) who underwent valve and/ or aortic surgery were included in this study. Intraoperative high-density epicardial mapping of the atria was performed during sinus rhythm to investigate unipolar potential voltages, conduction velocity (CV) and conduction block (CB). Results BAV patients were significantly younger than TAV patients (58 years vs. 68 years p=<0.001). Early de novo PoAF occurred in 20 (41%) BAV patients and 20 (38%) TAV patients. Among patients who developed PoAF, baseline characteristics showed no significant differences. Analysis of the whole atrium showed no significant differences in the median potential voltage (4.7 mV versus 4.4 mV, p=0.923), low voltage areas (7.1% versus 8.2%, p=0.865), CV (93.0 cm/s versus 93.8 cm/s, p=0.730) and CB prevalences (1.8 % versus 2.3 %, p=0.705) between the BAV PoAF and TAV PoAF group. (Figure 1) Furthermore, no significant regional differences were found in the electrophysiological parameters of the right atrium, Bachman’s bundle, left atrium and pulmonary veins between BAV and TAV patients who developed early de novo PoAF. Conclusions There were no differences in pre-existing atrial substrate in both BAV and TAV patients who developed early de novo PoAF. This could indicate that the risk of PoAF in these patients might be dependent on other peri- or postoperative factors.