Front. physiol. Front. physiol. Characterization of Atrial Propagation Patterns and Fibrotic Substrate With a Modified Omnipolar Electrogram Strategy in Multi-Electrode Arrays Riccio J Universidad de Zaragoza Alcaine A Rocher S Martinez-Mateu L Laranjo S Saiz J Laguna P Universidad de Zaragoza Martinez JP Universidad de Zaragoza 2021 research-article