Introduction. Aortic dissection is a cardiovascular emergency; the most frequent symptom is chest pain, but clinical presentation can be varied and atypical. Case Presentation. We report the case of a 66-year-old Caucasian male who presented a syncope immediately followed by a left-arm weakness while driving his car. Clinical examination was normal, but bilateral jugular vein distension was noted. Electrocardiogram and chest radiography were unremarkable. Among blood tests performed, troponin I test result was negative, and D-dimer test concentration was >4000 ng/mL. Since D-dimer test result was positive, chest computer tomography angiogram was performed and found a thoracic aortic dissection. Conclusion. Our case report shows that acute aortic dissection diagnosis is difficult and must be associated with the interpretation of various clinical signs and D-dimer measurement. It could be helpful for the emergency physician to have a pretest probability D-dimer like in pulmonary embolism diagnosis.