Rotors and breakthroughs as three-dimensional perpetuators of atrial fibrillation

Abstract

This editorial refers to ‘Heterogeneous atrial wall thickness and stretch promote scroll waves anchoring during atrial fibrillation’ by M. Yamazaki et al. , pp. 48–57, this issue. In previous years, disruption of electrical coupling between cardiac myocytes and muscle bundles, resulting in narrower—and thus more—fibrillation waves, was identified as the main mechanism underlying enhanced stability of atrial fibrillation (AF) in structurally remodelled atria.1 In addition, the rate of epicardial breakthrough was found to be enhanced in patients with persistent AF, which was hypothesized to be caused by more electrical dissociation between the epicardial layer and the endocardial bundle network.2 While endo-epicardial dissociation of electrical activity and breakthrough during AF were already described many years ago,3–5 this phenomenon was only recently demonstrated to be enhanced after several weeks to months of AF or rapid atrial pacing.6,7 Endo-epicardial dissociation of electrical activity is regarded the conditio sine qua non for the occurrence of transmural conduction and epicardial breakthrough. Such a ‘three-dimensional substrate’ for AF is believed to significantly contribute to the stabilization of AF over time. The study of Yamazaki et al. 8 adds several new aspects to the emerging concept of the three-dimensional substrate for AF. By the use of simultaneous endo-epicardial optical mapping, the authors were able to match two-dimensional high-resolution mapping data with each other and the underlying anatomical structures. This sophisticated …