Atrial fibrillation (AF) is the most common arrhythmia and a common cause of stroke, heart failure, and death. AF is induced by structural remodeling of the atria, also called atrial myopathy. Current therapy is limited to antiarrhythmic drugs and ablations, but these do not cure the disease. Since atrial myopathy is incompletely understood, we aim to define the molecular, cellular, and structural changes in atrial myopathy. To this end, we will use single-cell RNA sequencing and high-resolution microscopy on a pig model and on human atrial tissues. To integrate these diverse data sets and test their relationships in atrial myopathy that predisposes the tissue to AF, mathematical modelling approaches will be employed. Collectively, these versatile models will create a highly anticipated foundation for various applications, stretching from disease modeling to testing novel strategies for development of curative therapies for an ever-growing group of patients with AF.