Conduction Heterogeneity Impact of Underlying Heart Disease and Atrial Fibrillation

OBJECTIVES The goal of this study is to investigate the impact of various underlying heart diseases (UHDs) and prior atrial fibrillation (AF) episodes on conduction heterogeneity. BACKGROUND It is unknown whether intra-atrial conduction during sinus rhythm differs between various UHD or is influenced by AF episodes. METHODS Epicardial sinus rhythm mapping of the right atrium, Bachmann's bundle (BB), left atrium and pulmonary vein area was performed in 447 participants (median age: 67 [interquartite range (IQR): 59 to 73] years) with or without AF undergoing cardiac surgery for ischemic heart disease, (ischemic and) valvular heart disease, or congenital heart disease. Conduction times (CTs) were defined as Delta local activation time between 2 adjacent electrodes and used to assess frequency (CTs >= 4 ms) and magnitude of conduction disorders (in increments of 10 ms). RESULTS When comparing the 3 types of UHD, there were no differences in frequencies and magnitude of CTs at all locations (p >= 0.017 and p >= 0.005, respectively). Prior AF episodes were associated with conduction stowing throughout both atria (14.9% [1QR: 11.8 to 17.0] vs. 12.8% [IQR: 10.9 to 14.6]; p < 0.001). At BB, CTs with magnitudes >= 30 ms were more common in patients with AF (n = 56.2% vs. n = 36.0%; p < 0.004). CONCLUSIONS UHD has no impact on the frequency and severity of conduction disorders. AF episodes are associated with more conduction disorders throughout both atria and with more severe conduction disorders at BB. The next step will be to determine the relevance of these conduction disorders for AF development and maintenance. (C) 2020 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.