PROJECT SUMMARY/ABSTRACT Atrial fibrillation ablation is the most common procedure performed in electrophysiology laboratories and continues to grow more rapidly than any other EP procedure. A recent NHLBI report highlighted the research needs and priorities for catheter ablation of AF, emphasizing the importance of real-world evidence and the lack of longitudinal, multi-center, data collection platforms to inform patients and healthcare providers. The current proposal seeks to merge two extant resources to help fulfill those needs: the AF Ablation National Cardiovascular Data Registry (NCDR) and the NIH-supported Eureka mobile health research platform. The AF Ablation NCDR is a well-established quality assessment tool currently already in operation in 200 institutions around the US, utilizing comprehensive and carefully vetted and regularly audited data collection forms to ascertain detailed information regarding patient, procedure, and institution-level information. However, the AF Ablation NCDR does not capture longitudinal information regarding procedural effectiveness, safety, or patient reported outcomes. Eureka, co-developed and run by the proposed PI of the current project, is a digital infrastructure built to facilitate mobile health-based research, providing established workflows to obtain remote consent, actively engage with and collect information directly from research participants via a mobile app, employ technical integrations to passively collect data from smartphones, and utilizes a reliable and secure backend database to curate and transmit the resultant data. We propose to co-enroll AF Ablation NCDR patients into a customized Eureka tenant, enabling longitudinal data collection in a pragmatic fashion. While the overarching goal of this project will be to leverage these efforts to efficiently construct a resource available for multiple secondary analyses, ancillary projects, and future projects for interested investigators, we will demonstrate the utility of the merged infrastructure to pursue three immediately clinically relevant Aims. In Aim 1, we will determine the relative influences of patient-level, procedural-level, and institution-level characteristics as predictors of AF Ablation effectiveness and risk in this multi-center, real-world, prospective cohort, specifically testing the hypotheses that female sex, cryoablation (rather than radiofrequency ablation), and procedures performed in non-teaching hospitals will each be associated with reduced effectiveness and more frequent complication. In Aim 2, we will seek to determine how lifestyle factors may influence AF Ablation outcomes, specifically testing the hypothesis that reduced alcohol consumption after ablation is associated with greater effectiveness. In Aim 3, we will seek to demonstrate how this large multi-center database may be useful in characterizing rare but especially clinically relevant complications, specifically to describe the incidence and predictors o...