Management Approach for Unfolding of the Aorta on Chest X-ray

Initial Assessment and Risk Stratification

• The American College of Cardiology recommends further definitive imaging with CT, MRI, or transesophageal echocardiography to evaluate for thoracic aortic disease when unfolding of the aorta is detected on chest X-ray, as chest X-ray alone is inadequately sensitive to exclude significant aortic pathology 1, 2
• Chest X-ray findings suggestive of thoracic aortic disease should be interpreted based on the patient's pretest risk of disease, with high-risk patients proceeding directly to definitive aortic imaging regardless of chest X-ray findings, intermediate-risk patients using chest X-ray to establish alternative diagnoses, and low-risk patients using chest X-ray to identify findings suggestive of thoracic aortic disease 3
• Chest X-ray has significant limitations as a screening tool for thoracic aortic disease, with a sensitivity of only 64% for widened mediastinum and 71% for abnormal aortic contour, and cannot reliably exclude aortic dissection in all but the lowest-risk patients 1

Definitive Imaging Options

• Computed Tomography (CT) is the most commonly used initial diagnostic modality, with advantages including near-universal availability, ability to image the entire aorta, and short examination time, and provides sensitivities up to 100% and specificities of 98-99% 1, 4
• Transesophageal Echocardiography (TEE) is preferred for hemodynamically unstable patients requiring close monitoring, and provides additional information about cardiac and aortic valve function, as well as internal aortic diameter measurements 1, 6
• Magnetic Resonance Imaging (MRI) may be preferred for patients requiring repeated imaging to follow aortic abnormalities, and has comparable diagnostic accuracy to CT and TEE 5, 6

Management Considerations

• The American Heart Association recommends initial management of acute aortic dissection to focus on controlling heart rate with intravenous beta-blockers, using non-dihydropyridine calcium channel blockers if beta-blockers are contraindicated, reducing systolic blood pressure, and obtaining urgent surgical consultation regardless of anatomical location 7
• If initial imaging is negative but clinical suspicion remains high, a second imaging study should be obtained, with selection of specific imaging modality based on patient variables and institutional capabilities 3, 6

Important Caveats

• A completely normal chest X-ray does not exclude aortic dissection, particularly in patients without a clear alternative explanation for symptoms, and external aortic diameter should be reported for CT or MR measurements to accurately reflect external diameter in cases with intraluminal clot, wall inflammation, or dissection 1, 4
• Standardization of aortic diameter measurements is crucial for planning potential endovascular treatment, and the presence of a widened mediastinum or other radiographic findings suggestive of thoracic aortic disease increases the likelihood of aortic dissection 1