Conduction Disorders during Sinus Rhythm in Relation to Atrial Fibrillation Persistence.

Classification of atrial fibrillation (AF) is currently based on clinical characteristics. However, classifying AF using an objective electrophysiological parameter would be more desirable. The aim of this study was to quantify parameters of atrial conduction during sinus rhythm (SR) using an intra-operative high-resolution epicardial mapping approach and to relate these parameters to clinical classifications of AF. Patients were divided according to the standard clinical classification and spontaneous termination of AF episodes. The HATCH score, a score predictive of AF progression, was calculated, and surface ECGs were evaluated for signs of interatrial block. Conduction disorders mainly differed at Bachmann's bundle (BB). Activation time (AT) at BB was longer in persistent AF patients (AT-BB: 75 (53-92) ms vs. 55 (40-76) ms, p = 0.017), patients without spontaneous termination of AF episodes (AT-BB: 53.5 (39.6-75.8) ms vs. 72.0 (49.6-80.8) ms, p = 0.009) and in patients with a P-wave duration ≥ 120 ms (64.3 (52.3-93.0) ms vs. 50.5 (39.6-56.6) ms, p = 0.014). HATCH scores also correlated positively to AT-BB (rho 0.326, p = 0.029). However, discriminatory values of electrophysiological parameters, as calculated using ROC-curves, were limited. These results may reflect shortcomings of clinical classifications and further research is needed to establish an objective substrate-based classification of AF.