Acute aortic dissection (AD) is a deadly, difficult to diagnose disease presenting with an array of common and unspecific symptoms. Aortic dissection detection (ADD) risk score is a bedside clinical tool to estimate the risk of AD. D-dimer has been evaluated in several studies as a biomarker of AD and has showed a pooled diagnostic sensitivity of 97%. However, considering the severe morbidity and mortality of AD, a negative d-dimer per se is considered insufficient to rule-out AD in unselected patients.

The aim of the present study is to evaluate whether the diagnostic performance of d-dimer differs in patients at different clinical risk of AD, and in particular whether a negative d-dimer test may allow safe rule-out of AD in any patient subgroup without necessity to perform urgent aortic imaging.

Consecutive adult patients with suspected AD presenting to Emergency Department will be enrolled before the establishment of a final diagnosis; a standardized clinical form comprehensive of presence/absence of 12 risk markers allowing ADD risk score fulfilled and d-dimer levels measured at presentation.

The aortic imaging exam used to confirm or refuse of AD will be computed tomography angiography or transesophageal echocardiography and final diagnosis established after reviewing of all available data.

The accuracy, failure rate and efficiency of a diagnostic strategy combining standardized clinical stratification via the ADD risk score with d-dimer testing will therefore be assessed.

Acute AD will include the following etiological entities, also known as acute aortic syndromes: acute aortic dissection, intramural aortic hematoma, penetrating aortic ulcer and spontaneous aortic rupture.

A pre-specified secondary sub-analysis will evaluate the diagnostic accuracy of focus cardiac ultrasound (FoCUS) and chest x ray for suspected AD.

Inclusion Criteria:

• Age >18 years
• Presentation to the ED with any of the following symptoms: chest pain, back pain, abdominal pain, syncope or symptoms of perfusion deficit (central nervous system, mesenteric, myocardial, or limb ischemia)
• Aortic dissection considered among the differential diagnosis by the attending physician. Enrollment in the study will be decided by the attending physician during evaluation in the ED and before the establishment of a final diagnosis.

Exclusion Criteria:

• An alternative diagnosis to AD objectively established by the attending physician after the initial medical evaluation
• Clinical severity or other conditions not allowing complete evaluation/proper enrollment
• Lack of consent to participate to the study

Consecutive adult patients with suspected AD presenting to Emergency Departments will be enrolled at the time of initial medical evaluation and before the establishment of a final diagnosis