Prevalence and factors associated with false positive suspicion of acute aortic syndrome: experience in a patient population transferred to a specialized aortic treatment center

Acute aortic syndrome (AAS) is a medical emergency that requires prompt diagnosis and treatment at specialized centers. We sought to determine the frequency and etiology of false positive activation of a regional AAS network in a patient population emergently transferred for suspected AAS. We evaluated 150 consecutive patients transferred from community emergency departments directly to our Cardiac Intensive Care Unit (CICU) with a diagnosis of suspected AAS between March, 2010 and August, 2011. A final diagnosis of confirmed acute Type A, acute Type B dissection, and false positive suspicion of dissection was made in 63 (42%), 70 (46.7%) and 17 (11.3%) patients respectively. Of the 17 false positive transfers, ten (58.8%) were suspected Type A dissection and seven (41.2%) were suspected Type B dissection. The initial hospital diagnosis in 15 (88.2%) patients was made by a computed tomography (CT) scan and 10 (66.6%) of these patients required repeat imaging with an ECG-synchronized CT to definitively rule out AAS. Five (29.4%) patients had prior history of open or endovascular aortic repair. Overall in-hospital mortality was 9.3%. The diagnosis of AAS is confirmed in most patients emergently transferred for suspected AAS. False positive activation in this setting is driven primarily by uncertainty secondary to motion-artifact of the ascending aorta and the presence of complex anatomy following prior aortic intervention. Network-wide standardization of imaging strategies, and improved sharing of imaging may further improve triage of this complex patient population.