What are the diagnostic criteria for aortic dissection (AD)?

From the Guidelines

Diagnosing aortic dissection requires immediate medical attention and a combination of clinical assessment and imaging studies, with CT angiography being the most commonly used first-line test due to its wide availability, speed, and high accuracy. When aortic dissection is suspected, the initial evaluation includes a thorough history focusing on sudden, severe chest or back pain often described as tearing or ripping in nature, as recommended by the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1.

Clinical Assessment

The clinical assessment should include specific questions about medical history, family history, and pain features, as well as a focused examination to identify findings associated with aortic dissection, such as high-risk conditions and historical features, including Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, Turner syndrome, or other connective tissue disease 1.

• High-risk chest, back, or abdominal pain features include pain that is abrupt or instantaneous in onset, severe in intensity, or has a ripping, tearing, stabbing, or sharp quality.
• High-risk examination features include pulse deficit, systolic blood pressure limb differential greater than 20 mm Hg, focal neurologic deficit, and murmur of aortic regurgitation (new).

Imaging Studies

The definitive diagnosis relies on imaging studies, with the following options:

• CT angiography: the most commonly used first-line test due to its wide availability, speed, and high accuracy, as recommended by the 2022 ACC/AHA guideline 1.
• Transesophageal echocardiography (TEE): particularly useful in unstable patients or when CT is contraindicated.
• MRI: for stable patients with contrast allergies or renal insufficiency.
• Transthoracic echocardiography: may show indirect signs but is less sensitive.

Laboratory Tests

Laboratory tests like troponin and D-dimer may be ordered but are not specific for diagnosis. However, a nonelevated D-dimer (<500 ng/mL) makes the diagnosis unlikely, and integrating a low aortic dissection risk score and a low D-dimer may be a useful strategy to exclude the diagnosis of aortic dissection 1.

Classification and Treatment

Once diagnosed, aortic dissections are classified using either the Stanford (Type A involving the ascending aorta, Type B limited to the descending aorta) or DeBakey system to guide treatment decisions. Rapid diagnosis is essential as mortality increases approximately 1-2% per hour in untreated cases.

From the Research

Diagnosing Aortic Dissection

To diagnose aortic dissection, the following steps can be taken:

• A high index of suspicion is required, as aortic dissection may mimic other more common conditions that cause chest pain 2
• The diagnosis should be strongly considered in any patient with chest pain that is severe and unexplained by other findings or testing 3
• Patients who do not present with acute pain are often complicated by neurologic deficits, hypotension, or syncope, and have a higher rate of complications and mortality 3
• An educated understanding of the atypical presentations of aortic dissection helps the clinician to realistically rank it on the differential diagnosis, culminating in judicious use of definitive imaging 3

Clinical Features and Laboratory Tests

The following clinical features and laboratory tests can aid in the diagnosis of aortic dissection:

• Severe chest pain during exercise 4
• Arterial hypertension 4, 5
• Neurologic deficits, hypotension, or syncope 3
• Transthoracal echocardiography and computed tomography can be used to diagnose type I-aortic dissection 4
• Computed tomography angiography can be used to aid in the diagnosis of aortic dissection, but no single feature of the history or physical examination is enough to raise suspicion 3

Treatment and Management

The following treatment and management options are available for aortic dissection:

• Beta-blockers are known to protect a vulnerable aorta from acute dissection, as well as reducing the risk of recurrent dissection 4, 6, 5
• Surgery may be required to replace the ascending aorta 4
• Medical therapy, including beta-blockers, can be used to reduce systolic blood pressure and heart rate in non-surgical patients with type A aortic dissection 6
• However, there is no RCT evidence to support the current guidelines recommending the use of beta-blockers as first-line treatment of chronic type B TAD 5