Intro

Date: September 23, 2024 Reference: Essat et al. Diagnostic Accuracy of D-Dimer for Acute Aortic Syndromes: Systematic Review and Meta-Analysis. Annals of Emergency Medicine, May 2024 Guest Skeptic: Dr. Casey Parker is a Rural Generalist from Australia who is also an ultrasounder. Case: You are working a busy shift in a rural emergency department (ED) and your excellent Family Medicine trainee presents a case of a 63-year-old woman with chest pain and some intermittent radiation into the inter-scapular region. The patient has no specific risk factors for acute coronary syndrome (ACS) or dissection. The history is not overly concerning for dissection - the adjectives “severe”, and “ripping” or “tearing” are not used. Your trainee has done a great work-up and the possibility of an acute aortic dissection (AAD) is included in her differential diagnosis. Because this is a rural ED and the closest Computed tomography angiography (CTA) is a three-hour drive away, we must decide if this will benefit this patient. You accompany your trainee back to the bedside and clarify the nature of the chest pain, re-examine the patient and review all the available clinical data. There are no abnormalities in the blood work, ECG, or chest x-ray. Her pain seems to have settled. In this woman with no specific features of an aortic dissection, can we use a D-dimer assay to rule out this serious diagnosis and avoid a long and costly transfer? Background: Diagnosing acute aortic syndromes (AAS), which encompass life-threatening conditions like aortic dissection, intramural hematoma, and penetrating ulcers, can be challenging in the emergency department. These conditions typically present with nonspecific symptoms such as chest, back, or abdominal pain, and without early identification, they carry high morbidity and mortality. Aortic dissections are known for their rapid progression and the necessity for swift diagnosis and intervention. CTA is often the go-to imaging modality due to its high sensitivity and specificity for detecting AAS, but its routine use comes with risks—exposure to ionizing radiation and increased healthcare costs. In low-prevalence populations, over-reliance on CTA may be unwarranted. Emergency physicians have increasingly turned to the D-dimer test, a readily available blood test, to help rule out AAS and reduce unnecessary imaging. However, the effectiveness of D-dimer for diagnosing AAS remains debated due to variable test performance in different patient populations. The American College of Emergency Physicians (ACEP) has a policy on thoracic aortic dissections. They asked: “In adult patients with suspected acute nontraumatic thoracic aortic dissection, is a negative serum D-dimer sufficient to identify a group of patients at very low risk for the diagnosis of thoracic aortic dissection?” Answer: “In adult patients with suspected nontraumatic thoracic aortic dissection, do not rely on D-dimer alone to exclude the diagnosis of aortic dissection.” Clinical Question: What is the diagnostic accuracy of D-dimer for diagnosing acute aortic syndrome (AAS)? Reference: Essat et al. Diagnostic Accuracy of D-Dimer for Acute Aortic Syndromes: Systematic Review and Meta-Analysis. Annals of Emergency Medicine, May 2024 Population: Patients presenting to the ED with symptoms consistent with acute aortic syndromes, such as new-onset chest, back, or abdominal pain, syncope, or signs of perfusion deficit. Excluded: Patients with AAS following major trauma or as incidental findings, and studies using a case-control design. Intervention: D-dimer assay with variable cut-offs in trials but the primary analysis of trials using < 500 ng/ml. Comparison: The reference standard tests used for comparison included imaging modalities such as computed tomography angiography (CTA), ECG-gated CTA, echocardiography, magnetic resonance angiography, and confirmation through surgery or autopsy.