What is the most likely diagnosis for a patient with chest pain radiating to the back and a chest x-ray showing a wide mediastinum?

Aortic Dissection is the Most Likely Diagnosis

In a patient presenting with chest pain radiating to the back and a widened mediastinum on chest x-ray, aortic dissection (Option A) is the most likely diagnosis and must be assumed until proven otherwise.

Clinical Reasoning

Classic Presentation of Aortic Dissection

The combination of these two findings creates a high probability for aortic dissection:

• Chest pain radiating to the back is the classic presentation of aortic dissection, particularly when the pain has sudden onset with a "ripping" or "tearing" quality 1, 2, 3
• Widened mediastinum on chest x-ray is present in 62.6% of type A and 56% of type B aortic dissections 4, and when combined with severe pain of abrupt onset and pulse differential, creates >80% probability of dissection 1

Why Not Esophageal Rupture?

While esophageal rupture can present with chest pain and widened mediastinum, several factors make it less likely:

• Esophageal rupture typically requires a precipitating event: forceful vomiting (Boerhaave syndrome), instrumentation, or trauma 1
• Additional findings expected: subcutaneous emphysema (present in most cases), pneumothorax (20% of patients), and unilateral decreased breath sounds 1
• The clinical context matters: without mention of vomiting or instrumentation, esophageal rupture becomes significantly less probable

Immediate Diagnostic Approach

CT angiography of the chest is the definitive diagnostic test and should be obtained immediately 2:

• Sensitivity and specificity exceeding 95% for aortic dissection 2
• Provides rapid visualization of the intimal flap, true and false lumens, and extent of dissection 2
• Can also identify alternative diagnoses if dissection is excluded 2

Critical Management Steps

While arranging imaging 2:

1. Stabilize hemodynamics - control heart rate with IV beta-blockers and reduce systolic blood pressure 5
2. Obtain urgent surgical consultation - Type A dissections require emergency cardiac surgery 2, 6
3. Avoid thrombolytics - if STEMI is also suspected on ECG, do not give anticoagulation until dissection is excluded 7

Important Clinical Caveats

• Normal chest x-ray does not exclude aortic dissection - sensitivity for widened mediastinum is only 64% 5
• Absence of classic triad does not rule out dissection - even with 0 of 3 high-risk features (aortic pain characteristics, mediastinal widening, pulse differentials), 4% of patients still had aortic dissection 1
• Pulse deficits occur in only 30% of patients but when present (especially ≥3 deficits), predict 60% in-hospital mortality 4
• Painless presentations exist - aortic dissection can present atypically with stroke, gait disturbance, or other neurological symptoms 8

The combination of chest pain radiating to the back plus widened mediastinum mandates immediate evaluation for aortic dissection with CT angiography 2, 6.