Search strategy
A systematic search of the literature was performed, up to July 2020, in three databases: Medline (via PubMed), Scopus and Cohrane Library, using the following search strategy based on keywords: ((atrial) OR (atria) OR (atrium)) AND ((reservoir) OR (strain) OR (stiffness)) AND ((atrial fibrillation) OR (af)). Additional hand- search was also performed using the references of the articles that were identified as relevant (snowball strategy). No date restriction was used. Articles not available in english were excluded.