The Neuro-AFib Study will be conducted in two phases to collect current data on both ischemic and hemorrhagic stroke patients with NVAF. The data collected for this study will enhance our understanding of atrial fibrillation related stroke and the benefits and limitations of current management strategies. Phase I will consist of retrospective data collection and Phase II will consist of prospective enrollment. We will be collecting data on over 6,000 stroke patients for Phase I and about 3,000 prospectively enrolled patients in Phase II. Phase I is currently composed of 23 participating sites are located across the United States. This is an Investigator Initiated Research study sponsored and run by Massachusetts General Hospital. Boston Scientific Corporation (BSC) is providing Massachusetts General Hospital with funding to conduct the study. BSC does not have any control over the study design, data acquisition, analysis or interpretation and BSC will not collect any data from this study. This study is also supported by the Heitman Young Investigator Award.