Atrial fibrillation (AF) is a debilitating cardiac arrythmia that is associated with increased morbidity and mortality. More specifically, it is associated with a fivefold risk for stroke and is even estimated to cause 15 % of all strokes. In addition, it is associated with a twofold risk for all-cause mortality, independent of co-morbid conditions . While a multitude of etiologies could be responsible for the generation of AF, recent work has shown that new-onset supraventricular tachyarrhythmias including AF affect 15 % to 40 % of patients following cardiothoracic surgery. Furthermore, new-onset AF in cardiothoracic surgery is associated with a prolonged hospital course and increases a patient's risk of morbidity and mortality. For example, it has been documented in the past that patients who undergo abdominal aortic aneurysm (AAA) repair and develop AF had higher rates of mortality both post-operatively and post-discharge . Moreover, in patients undergoing thoracic aortic aneurysm repairs, it is thought that closer proximity to the atria and supplying vessels has a larger likelihood of disrupting electrical networks and, thus, producing AF. In these patient populations, new-onset AF following surgery is associated with a greater risk of myocardial infarction (MI) and, therefore, a more complicated post-operative course . Additional research has been done to explore new-onset AF following aortic aneurysm repair surgeries; however, there has been a lack of work that looks to assess outcomes in patients undergoing aortic aneurysm repair with pre-existing AF as opposed to new-onset AF.