7. Project Summary Current treatments for persistent atrial fibrillation (AF) are associated with high recurrence rates due to our limited understanding of how AF develops and sustains. In patients with AF, structural remodeling in the form of fibrosis is often present, indicating that structural remodeling may have a role in AF development. This project aims to identify the role of fibrosis in AF by using a transgenic goat model. In aim 1, we strive to show the importance of structural remodeling compared to electrical remodeling in AF developing. In aim 2, the architecture of structural remodeling will be investigated to identify if differences in the underlying fibrotic architecture lead to increased AF susceptibility. In aim 3, the fibrotic architecture will be compared to in-vivo electrical mapping data to determine how varying degrees of fibrosis affect conduction patterns. The results of this project will investigate if there is a causal relationship between structural remodeling and impaired conduction. Success in this project will lead to improved ablation targets for patients with persistent AF, leading to lower recurrence rates. Completing this project provides valuable scientific and technical training to develop into an independent researcher.