Aortic dissection: effect of prospective chest radiographic diagnosis on delay to definitive diagnosis

Integrated Use of Conventional Chest Radiography Cannot Rule Out Acute Aortic Syndromes in Emergency Department Patients at Low Clinical Probability

OBJECTIVES

Guidelines recommend chest radiography (CR) in the workup of suspected acute aortic syndromes (AASs) if the pretest clinical probability is low. However, the diagnostic impact of CR integration for the rule-in and rule-out of AASs is unknown.

METHODS

We performed a secondary analysis of the ADvISED multicenter study. Emergency department outpatients were eligible if an AAS was clinically suspected. Clinical probability was defined with the aortic dissection detection risk score (ADD-RS). CR was evaluated blindly by a radiologist, who judged on mediastinum enlargement (ME) and other signs.

RESULTS

In 2014 through 2016, a total of 1,129 patients were enrolled and 1,030 were analyzed, including 48 (4.7%) with AASs. ADD-RS/ME and ADD-RS/any CR sign (aCRs) integration were more accurate than ADD-RS alone (area under the curve = 0.8 and 0.78 vs. 0.66, p < 0.001). The sensitivity and specificity of the integrated strategies were 66.7% (95% confidence interval [CI] = 51.5% to 79.9%) and 82.5% (95% CI = 79.9% to 84.8%) for ADD-RS/ME and 68.8% (95% CI = 53.6% to 80.9%) and 76.5% (95% CI = 73.7% to 79.1%) for ADD-RS/aCRs, respectively. The sensitivity and specificity of CR per se were 54.2% (95% CI = 39.2% to 68.6%) and 92.4% (95% CI = 90.5% to 93.9%) for ME and 60.4% (95% CI = 45.3% to 74.2%) and 85.2% (95% CI = 82.9% to 87.4%) for aCRs. The agreement (κ) between attending physicians and radiologists for ME was 0.44 (95% CI = 0.35 to 0.54). ADD-RS/ME rule-in (ADD-RS ≤ 1 and ME-present, or ADD-RS > 1) applied to 204 versus 130 patients with ADD-RS > 1, including 14 with AAS and 60 false-positives (FP). ADD-RS/aCRs rule-in (ADD-RS ≤ 1 and aCRs-present, or ADD-RS > 1) applied to 264 patients, including 15 with AAS and 119 FP. ADD-RS/ME rule-out (ADD-RS ≤ 1 and ME-absent) applied to 826 (80.2%) patients, including 16 with AAS (33.3% of cases). ADD-RS/aCRs rule-out (ADD-RS ≤ 1 and aCRs-absent) applied to 766 patients (74.4%), including 15 with AAS (31.3% of cases).

CONCLUSIONS

CR integration with clinical probability assessment showed modest rule-in efficiency and insufficient sensitivity for conclusive rule-out.

The diagnostic accuracy of the mediastinal width on supine anteroposterior chest radiographs with nontraumatic Stanford type A acute aortic dissection

Background

Nontraumatic Stanford type A acute aortic dissection is a life‐threatening condition; thus, the ability to make a precise diagnosis of nontraumatic Stanford type A acute aortic dissection is essential for the emergency physician. Several reports have shown that the mediastinal widening on a chest radiograph is useful for the diagnosis of nontraumatic Stanford type A acute aortic dissection; however, the exact cutoff value of the mediastinal width on plain radiographs is rarely defined.

Methods

A single‐center retrospective case‐control study was conducted between October 1, 2013, and March 31, 2015. We evaluated the maximal mediastinal width of the anteroposterior chest X‐ray at the level of the aortic knob in the supine position between patient groups with and without nontraumatic Stanford type A acute aortic dissection.

Results

We enrolled 72 patients (36 patients with nontraumatic Stanford type A acute aortic dissection and 36 patients without nontraumatic Stanford type A acute aortic dissection). The median mediastinal width of patients with nontraumatic Stanford type A acute aortic dissection was significantly larger than that of patients without nontraumatic Stanford type A acute aortic dissection (100.7 mm vs 77.7 mm, P < .01). The optimal cutoff level was 87 mm (sensitivity, 81%; specificity, 89%). Using multivariable logistic regression, the odds ratio of a mediastinal width of >87 mm for a diagnosis nontraumatic Stanford type A acute aortic dissection was 57.1 (95% confidence interval, 11.2‐290.2).

Conclusion

A mediastinal width of >87 mm showed high sensitivity in the diagnosis of probable nontraumatic Stanford type A acute aortic dissection.

Acute aortic syndromes

Acute aortic syndrome is a term that describes one of a number of different pathologic entities. Each of these conditions requires urgent or emergent evaluation and may possibly require surgical intervention. However, both entities may be unfamiliar to the nonsurgical (and in some cases, surgical) practitioner and they may mimic more common diseases or be missed entirely. An understanding of the processes, nomenclature, and management options is critical in optimizing patient care.

The inadvertent administration of anticoagulants to ED patients ultimately diagnosed with thoracic aortic dissection

OBJECTIVES

Aortic dissection (AD) may present similarly to acute coronary syndrome or pulmonary embolus; however, anticoagulation may be detrimental to patients with AD.

METHODS

Clinical data were abstracted from medical records of emergency department (ED) patients with nontraumatic AD. Patients administered with anticoagulants were compared with non-anticoagulated patients with regard to presenting symptoms, chest radiograph and electrocardiogram (ECG) findings, and outcome.

RESULTS

A total of 44 ED patients with nontraumatic AD was identified over a 4-year period; anticoagulants were administered to 9 (21%). Anticoagulated patients had a higher incidence of chest pain without back pain (78% vs 23%; P = .002) and ST elevations or depressions on ECG (89% vs 6%; P < .001) and were less likely to have a widened mediastinum on chest radiograph (0% vs 67%; P < .001). Two ED anticoagulated patients died, one required a second surgery for bleeding complications, and another suffered a stroke after reversal of anticoagulation.

CONCLUSIONS

There is a clinically significant incidence of anticoagulation administration to ED patients ultimately diagnosed with AD, especially in the presence of ambiguous ECG and radiographic findings.

Chest radiography for the diagnosis of acute aortic syndrome

PURPOSE

We sought to assess the diagnostic accuracy of routine chest radiography for the acute aortic syndrome (dissection, intramural hematoma, penetrating ulcer, or nondissecting aneurysm).

METHODS

During a 6-year period, 216 patients (143 men, 73 women; mean [+/- SD] age, 58 +/- 17 years) underwent chest radiography for suspected acute aortic syndrome. Chest films were re-evaluated blindly for aortic disease, based on an overall impression using standard criteria such as widening of the aortic contour and mediastinal shadow. Findings were matched to tomographic images, anatomical inspection, or both, as the criterion standard; aortic disease was confirmed in 109 (50%) of the patients.

RESULTS

Chest radiography had a sensitivity of 64% (70/109) and a specificity of 86% (92/107) for aortic disease. Sensitivity was 67% (38/57) for overt aortic dissection, 61% (22/36) for nondissecting aneurysm, and 63% (10/16) for intramural hemorrhage or penetrating ulcer. However, sensitivity was lower for pathology confined to the proximal aorta (47% [21/45]) than for disease involving distal aortic segments (77% [49/64]). A receiver operating characteristic curve analysis of aortic diameters failed to identify a threshold for the diagnosis of aortic disease.

CONCLUSION

Chest radiography is of limited value for diagnosing the acute aortic syndrome, particularly for conditions confined to the ascending aorta. Since a definitive diagnosis is required in any patient with clinically suspected acute aortic syndrome, routine chest radiography should be replaced by tomographic aortic imaging.