How to exclude aortic dissection in a patient with chest pain?

From the Guidelines

To exclude aortic dissection in a patient with chest pain, a CT angiogram of the chest and abdomen with contrast is the most definitive diagnostic test, given its high sensitivity and specificity, as evidenced by a large retrospective study 1. This approach is crucial because aortic dissection is life-threatening with high mortality if missed, and early diagnosis significantly improves outcomes.

Initial Assessment

When evaluating a patient with chest pain for possible aortic dissection, it's essential to start with a thorough history and physical examination, focusing on risk factors like hypertension, Marfan syndrome, bicuspid aortic valve, and family history of aortic disease. Vital signs should be checked in both arms to identify blood pressure differentials (>20 mmHg suggests possible dissection).

Diagnostic Tests

• CT Angiogram: The most definitive diagnostic test for detecting aortic dissection, with a sensitivity of 99% and specificity of 100% 1.
• Transesophageal Echocardiography (TEE): Useful for proximal dissections or when CT is contraindicated, but has a lower sensitivity of 88% compared to CT 1.
• MRI: Provides excellent visualization but may be impractical in emergency situations and has limited availability.
• Laboratory Tests: D-dimer can help, with a negative result having a high negative predictive value, though it's not specific 1.
• Troponin and ECG: Should be performed to rule out myocardial infarction, which can present similarly.

Management

While awaiting definitive diagnosis, blood pressure control is crucial if dissection is suspected, typically using IV beta-blockers like metoprolol (5-15 mg IV) or labetalol (10-20 mg IV) to target a systolic BP of 100-120 mmHg, followed by vasodilators if needed 1. The selection of a specific imaging modality should be based on patient variables and institutional capabilities, including immediate availability 1. If a high clinical suspicion exists for acute aortic dissection but initial aortic imaging is negative, a second imaging study should be obtained 1.

Key Considerations

• The presence of ST-segment elevation suggestive of myocardial infarction should be treated as a primary cardiac event without delay for definitive aortic imaging unless the patient is at high risk for aortic dissection 1.
• Chest x-ray may be useful in establishing an alternate diagnosis or demonstrating findings suggestive of thoracic aortic disease, especially in intermediate and low-risk patients 1.

From the Research

Excluding Aortic Dissection in Patients with Chest Pain

To exclude aortic dissection in a patient with chest pain, several diagnostic tools and approaches can be considered:

• Point-of-Care Ultrasound (POCUS): Emergency POCUS can be a useful diagnostic tool to help differentiate aortic dissection from a primary myocardial infarction, as it is fast and accessible with high specificity for the diagnosis of aortic dissection in the emergency department 2.
• Computed Tomography Angiography (CTA): CTA is the imaging modality most frequently used to diagnose type A aortic dissection with a high degree of sensitivity and specificity 3.
• Transesophageal Echocardiography: This can establish the diagnosis responsible for the symptoms in patients with clinically suspected acute aortic dissection and can identify alternate cardiovascular pathology responsible for the symptoms in a significant number of patients without acute dissection 4.
• Clinical Presentation: Aortic dissection can present with a broad spectrum of signs and symptoms, including chest and back pain, syncope, and congestive heart failure. Maintaining a high level of suspicion for this diagnosis is key, especially in patients with an ascending aortic aneurysm, even in the absence of initial classic features of dissection on computed tomography angiography 5, 6, 3.

Diagnostic Challenges

• Misdiagnosis: Aortic dissection may be misdiagnosed as myocardial infarction or other conditions, highlighting the need for a thorough diagnostic approach 6.
• False Negatives: Despite the high sensitivity and specificity of CTA, false negatives can occur, and clinical judgment is crucial in deciding the need for further investigation or surgical intervention 3.

Importance of Early Diagnosis

• Mortality: Untreated patients with aortic dissection have a high mortality rate, emphasizing the importance of early diagnosis and treatment 5.
• Treatment Outcomes: Appropriate medical treatment and corrective surgery can significantly improve outcomes, with success rates exceeding 90% in some cases 5.