Detecting acute thoracic aortic dissection in the emergency department: time constraints and choice of the optimal diagnostic test

Diagnosis of acute aortic syndromes with ultrasound and d-dimer: the PROFUNDUS study

BACKGROUND

In patients complaining common symptoms such as chest/abdominal/back pain or syncope, acute aortic syndromes (AAS) are rare underlying causes. AAS diagnosis requires urgent advanced aortic imaging (AAI), mostly computed tomography angiography. However, patient selection for AAI poses conflicting risks of misdiagnosis and overtesting.

OBJECTIVES

We assessed the safety and efficiency of a diagnostic protocol integrating clinical data with point-of-care ultrasound (POCUS) and d-dimer (single/age-adjusted cutoff), to select patients for AAI.

METHODS

This prospective study involved 12 Emergency Departments from 5 countries. POCUS findings were integrated with a guideline-compliant clinical score, to define the integrated pre-test probability (iPTP) of AAS. If iPTP was high, urgent AAI was requested. If iPTP was low and d-dimer was negative, AAS was ruled out. Patients were followed for 30 days, to adjudicate outcomes.

RESULTS

Within 1979 enrolled patients, 176 (9 %) had an AAS. POCUS led to net reclassification improvement of 20 % (24 %/-4 % for events/non-events, P < 0.001) over clinical score alone. Median time to AAS diagnosis was 60 min if POCUS was positive vs 118 if negative (P = 0.042). Within 941 patients satisfying rule-out criteria, the 30-day incidence of AAS was 0 % (95 % CI, 0-0.41 %); without POCUS, 2 AAS were potentially missed. Protocol rule-out efficiency was 48 % (95 % CI, 46-50 %) and AAI was averted in 41 % of patients. Using age-adjusted d-dimer, rule-out efficiency was 54 % (difference 6 %, 95 % CI, 4-9 %, vs standard cutoff).

CONCLUSIONS

The integrated algorithm allowed rapid triage of high-probability patients, while providing safe and efficient rule-out of AAS. Age-adjusted d-dimer maximized efficiency.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov, NCT04430400.

National survey of emergency physicians on the risk stratification and acceptable miss rate of acute aortic syndrome

OBJECTIVES

One in four cases of acute aortic syndrome are missed. This national survey examined Canadian Emergency physicians' opinion on risk stratification, the need for a clinical decision aid to risk stratify patients, and the required sensitivity of such a tool.

METHODS

We surveyed 1,556 members of the Canadian Association of Emergency Physicians. We used a modified Dillman technique with a prenotification email and up to three survey attempts using electronic mail. Physicians were asked 21 questions about demographics, importance of certain high-risk features, investigation options, threshold for investigation, and if a clinical decision tool is required.

RESULTS

We had a response rate of 32%. Respondents were 66% male, and 49% practicing >10 years, with 59% in an academic teaching hospital. A total of 93% reported a need for a clinical decision aid to risk stratify for acute aortic syndrome. A total of 99.6% of physicians were pragmatic accepting a non-zero miss-rate, two-thirds accepting <1%, and the remaining accepting a higher miss-rate.

CONCLUSIONS

Our national survey determined that emergency physicians would use a highly sensitive clinical decision aid to determine which patients are at low, medium, or high-risk for acute aortic syndrome. The majority of clinicians have a low threshold (<1%) for investigating for acute aortic syndrome, but accept that a zero miss-rate is not feasible.

Acute type A aortic dissection: Aortic Dissection Detection Risk Score in emergency care – surgical delay because of initial misdiagnosis

Background:

Acute type A aortic dissection requires immediate surgical treatment, but the correct diagnosis is often delayed. This study aimed to analyse how initial misdiagnosis affected the time intervals before surgical treatment, symptoms associated with correct or incorrect initial diagnosis and the potential of the Aortic Dissection Detection Risk Score to improve the sensitivity of initial diagnosis.

Methods:

We conducted a retrospective analysis of 350 patients with acute type A aortic dissection. Patients were divided into two groups: initial misdiagnosis (group 0) and correct initial diagnosis of acute type A aortic dissection (group 1). Symptoms were analysed as predictors for the correct or incorrect initial diagnosis by multivariate analysis. Based on these findings, the Aortic Dissection Detection Risk Score was calculated retrospectively; a result ⩾2 was defined as a positive score.

Results:

The early suspicion of aortic dissection significantly shortened the median time from pain to surgical correction from 8.6 h in patients with an initial misdiagnosis to 5.5 h in patients with the correct initial diagnosis (p&lt;0.001). Of all acute type A aortic dissection patients, 49% had a positive Aortic Dissection Detection Risk Score. Of all initial misdiagnosed patients, 41% had a positive score (⩾2). The presence of lumbar pain (p&lt;0.001), any paresis (p=0.037) and sweating (p=0.042) was more likely to lead to the correct initial diagnosis.

Conclusion:

An early consideration of acute aortic dissection may reduce the delay of surgical care. The suggested Aortic Dissection Detection Risk Score may be a useful tool to improve the preclinical assessment.

Discriminatory Value of the Ascending Aorta Diameter in Suspected Acute Type A Aortic Dissection

OBJECTIVE

The objective was to determine if ascending aorta (AscAo) diameters measured by noncontrast computed tomography (CT) allow for meaningful discrimination between patients with and without type A aortic dissection (TAAD), ideally with 100% sensitivity.

METHODS

This study was a retrospective analysis of cases of TAAD, as well as controls, undergoing evaluation for TAAD with CT aortography, presenting to 21 emergency departments within an integrated health system between 2007 and 2015. AscAo diameters were determined using axial noncontrast CT images at the level of the right main pulmonary artery by two readers. AscAo diameters were additionally normalized for age, sex, and body surface area (assessed by a Z-score, which is the number of standard deviations between the observed and expected AscAo diameters). Overall model discrimination was assessed using the area under the receiver operating characteristic curve (AUC). Comparative discrimination was assessed using both the change in AUC (∆AUC) and the continuous net reclassification index (NRI).

RESULTS

A total of 230 cases of TAAD and 325 controls were included in the study. The median ages for cases and controls were 65 and 62 years, and the median AscAo diameters were 50 and 35 mm, respectively. The raw and normalized AscAo diameters demonstrated similarly excellent discrimination (AUCs of 0.96 vs. 0.97, respectively; ∆AUC = 0.01, p = 0.09) and an NRI of 0.30 (95% confidence interval [CI] = 0.13-0.47), both indicating small incremental improvements in classification with the use of the normalized AscAo measures. A raw AscAo diameter of 34 mm and a normalized Z-score of 1.84 both yielded 100% sensitivity for TAAD, with respective specificities of 35% (95% CI = 29.6%-40.2%) and 67% (95% CI = 61.7%-72.2%).

CONCLUSIONS

Nearly all patients with TAAD appear to have enlarged AscAo diameters as measured by noncontrast CT, whereas most patients with suspected but absent TAAD have relatively normal AscAo diameters. Both raw and normalized AscAo measures provided relatively comparable discriminatory value. If validated, these data may be useful in adjudicating risk among patients with suspected TAAD in whom a criterion standard test is unavailable, nondiagnostic, or contraindicated.

Delay from Diagnosis to Surgery in Transferred Type A Aortic Dissection

OBJECTIVES

The purpose of this research is to analyze factors associated with delays to surgical management of Type A acute aortic dissection patients.

METHODS

Time from diagnosis to surgery and associated factors were evaluated in 1880 surgically managed Type A dissection patients enrolled in the International Registry of Acute Aortic Dissection.

RESULTS

The majority of patients were transferred (75.7% vs 24.3%). Patients who were transferred had a median delay from diagnosis to surgery of 4.0 hours (interquartile range 2.5-7.2 hours), compared with 2.3 hours (interquartile range 1.1-4.2 hours; P < .001) in nontransferred patients. Among patients who were transferred, those with worst-ever, posterior, or tearing chest pain those with severe complications, and those receiving transthoracic echocardiogram prior to a transesophageal echocardiogram or as the only echocardiogram were treated more quickly. Those undergoing magnetic resonance imaging, or who had prior cardiac surgery, had longer delays to surgery. Among nontransferred patients, those with coma were treated more quickly. In both groups, patients presenting with emergent conditions such as cardiac tamponade, hypotension, or shock had more rapid treatment. Among transferred patients, surviving patients had longer delays (4.1 [2.6-7.8] hours vs 3.3 [2.0-6.0] hours, P = .001). Overall mortality did not differ between patients who were transferred vs not (19.3% vs 21.1%, P = .416).

CONCLUSION

Simply being transferred added significantly to the delay to surgery for Type A acute aortic dissection patients, but a number of factors affected its extent. Overall, signs and symptoms leading to a definitive diagnosis or indicating immediate life threat reduced time to surgery, while factors suggesting other diagnoses correlated with delays.

Diagnostic performance of emergency transthoracic focus cardiac ultrasound in suspected acute type A aortic dissection

Type A aortic dissection (AD) is a deadly disease. Rapid identification of patients requiring immediate advanced aortic imaging or transfer to specialized centers is needed to improve outcomes. We evaluated the diagnostic performance of transthoracic focus cardiac ultrasound (FOCUS) performed by emergency physicians, alone and in combination with the aortic dissection detection (ADD) risk score in suspected type A AD. This was a prospective study performed on patients with suspected type A AD. FOCUS evaluated the presence of intimal flap/intramural hematoma (direct signs of AD), ascending aorta dilatation, aortic valve insufficiency or pericardial effusion/tamponade (indirect signs of AD). The ADD risk score of each patient was calculated according to guidelines. The final diagnosis was established after review of complete clinical data. 50 (18%) patients of 281 had a final diagnosis of type A AD. Detection of any FOCUS sign (direct or indirect) of AD had a sensitivity of 88% (95% CI 76-95%) for the diagnosis of type A AD. Presence of ADD risk score > 0 or detection of any FOCUS sign increased diagnostic sensitivity to 96% (95% CI 86-99%). Detection of direct FOCUS signs had a specificity of 94% (95% CI 90-97%), while combination of ADD risk score > 1 with detection of direct FOCUS signs had a specificity of 98% (95% CI 96-99%). FOCUS demonstrated acceptable accuracy as a triage tool to rapidly identify patients with suspected type A AD needing advanced aortic imaging or transfer, but it cannot be used as a stand-alone test even if combined with ADD risk score classification.

Combined use of aortic dissection detection risk score and D-dimer in the diagnostic workup of suspected acute aortic dissection

BACKGROUND

Acute aortic dissection (AD) represents a diagnostic conundrum. Validated algorithms are particularly needed to identify patients where AD could be ruled out without aortic imaging. We evaluated the diagnostic accuracy of a strategy combining the aortic dissection detection (ADD) risk score with D-dimer, a sensitive biomarker of AD.

METHODS

Patients from two clinical centers with suspected AD were prospectively enrolled in a registry, from January 2008 to March 2013. The ADD risk score was calculated by retrospective blinded chart review. For D-dimer, a cutoff of 500 ng/ml was applied.

RESULTS

AD was diagnosed in 233 of 1035 (22.5%) patients. The ADD risk score was 0 in 322 (31.1%), 1 in 508 (49.1%) and >1 in 205 (19.8%) patients. The sensitivity and the failure rate of D-dimer were 100% and 0% in patients with ADD score 0, versus 97.5% (95% CI 91.4-99.6%) and 4.2% (95% CI 0.7-12.5%) in patients with ADD risk score >1. In patients with ADD risk score ≤ 1, the sensitivity and the failure rate of D-dimer were 98.7% (95% CI 95.3-99.8%) and 0.8% (95% CI 0.1-2.6%). The diagnostic efficiency of D-dimer in patients with ADD risk score 0 and ≤ 1 was 8.9% (95% CI 7.2-10.7%) and 23.6% (95% CI 21.1-26.2%) respectively.

CONCLUSIONS

In a large cohort of patients with suspected AD, the presence of ADD risk score 0 or ≤ 1 combined with a negative D-dimer accurately and efficiently ruled out AD.

A fatal outcome of thoracic aortic aneurysm in a male patient with bicuspid aortic valve

Thoracic aortic aneurysm is often an asymptomatic but potentially lethal disease if its most catastrophic complication – aortic dissection – occurs. Thoracic aortic dissection is associated with a high mortality rate despite ongoing improvement in its management. We report a fatal outcome of thoracic aortic aneurysm in a male patient with bicuspid aortic valve. The patient was qualified for elective surgery of the ascending aorta and aortic valve at the age of 39 but he did not agree to undergo the proposed procedure. Three years later, he experienced acute aortic dissection and died despite a prompt diagnosis and complex management.

Pictorial review: computed tomography features of cardiovascular emergencies and associated imminent decompensation

Multi-detector computed tomography (MDCT) scanner is available in most hospitals and is increasingly being used as the first line imaging in trauma and suspected cardiovascular emergencies, such as acute coronary syndrome, pulmonary artery thrombo-embolism, abdominal aortic aneurysm and acute haemorrhage (Ryan et al. Clin Radiol 60:599-607, 2005). A significant number of these patients are haemodynamically unstable and can rapidly progress into shock and death. Recognition of computed tomography (CT) signs of imminent cardiovascular decompensation will alert the clinical radiologist to the presence of shock. In this review, the imaging findings of cardiovascular emergencies in both acute traumatic and non-traumatic settings with associated signs of imminent decompensation will be described and illustrated.

Acute aortic dissection: be aware of misdiagnosis

Background

Acute aortic dissection (AAD) is a life-threatening condition requiring immediate assessment and therapy. A patient suffering from AAD often presents with an insignificant or irrelevant medical history, giving rise to possible misdiagnosis. The aim of this retrospective study is to address the problem of misdiagnosing AD and the different imaging studies used.

Methods

From January 2000 to December 2004, 49 patients (41 men and 8 women, aged from 18–75 years old) presented to the Emergency Department of our hospital for different reasons and finally diagnosed with AAD. Fifteen of those patients suffered from arterial hypertension, one from giant cell arteritis and another patient from Marfan's syndrome. The diagnosis of AAD was made by chest X-ray, contrast enhanced computed tomography (CT), transthoracic echocardiography (TTE) and coronary angiography.

Results

Initial misdiagnosis occurred in fifteen patients (31%) later found to be suffering from AAD. The misdiagnosis was myocardial infarction in 12 patients and cerebral infarction in another three patients.

Conclusion

Aortic dissection may present with a variety of clinical manifestations, like syncope, chest pain, anuria, pulse deficits, abdominal pain, back pain, or acute congestive heart failure. Nearly a third of the patients found to be suffering from AD, were initially otherwise diagnosed. Key in the management of acute aortic dissection is to maintain a high level of suspicion for this diagnosis.

Pathophysiology, diagnosis, and management of aortic dissection

Aortic dissection is an uncommon but potentially fatal disease with catastrophic complications. A high level of suspicion is required for successful diagnosis as presenting symptoms are so variable that dissection may be overlooked in up to 39% of cases. It most commonly presents in the elderly population with a history of chronic hypertension. Rapid intervention is necessary as delay leads to higher mortality. Despite advances in diagnostic and therapeutic techniques, morbidity and mortality remains high. Advances in diagnostic imaging have raised the awareness of variants of aortic dissection, including intramural hemorrhage and penetrating aortic ulcer. This distinction is important as the clinical course of these variants differs from that of classical aortic dissection, and thus treatment may also differ. Understanding of these variants has also led to the recognition of markers that may help predict progression to classical aortic dissection and thus warrant closer vigilance in selected patient populations. The recognition that rapid diagnosis is required for management of aortic dissection has led to the investigation of serum tests as diagnostic aids. Serum smooth muscle myosin heavy chain, d-dimer, and serum soluble elastin fragments are promising tests that may help raise suspicion for the diagnosis of acute aortic dissection. The high mortality associated with surgical therapy has led to investigation of alternative approaches. Endovascular therapy has emerged as a viable option in patients with type B dissection who are too unstable for surgery. However, long-term follow up is required to validate this procedure.

Descending Thoracic Aortic Dissection: Evaluation and Management in the Era of Endovascular Technology

Acute aortic dissection is a relatively uncommon but highly lethal condition. Without proper treatment, devastating consequences can occur due to aortic rupture, cardiac tamponade, or irreversible ischemia involving the spinal cord or the visceral organs. The treatment strategy of this condition is in part influenced by the location and the severity of aortic dissection as immediate surgical intervention is necessary in acute ascending aortic dissection, whereas medical therapy is the initial treatment approach in uncomplicated descending aortic dissection. Recent advances of endovascular technology have broadened the potential application of this catheter-based therapy in aortic pathologies, including descending thoracic aortic dissection. In this article, the etiology, pathogenesis, and classification of this condition are discussed. The diagnostic benefits of various imaging modalities for descending aortic dissection are also discussed. Current treatment strategies, including medical, surgical, and catheter-based interventions, are reviewed. Lastly, clinical experiences of endovascular treatment for descending aortic dissection and various endovascular devices potentially applicable for this condition are discussed.

The utility of multiple imaging modalities to diagnose acute aortic dissection

A 21-year-old man with Marfan syndrome and known aortic root aneurysm presented to our emergency department with symptoms suggestive of acute aortic dissection. The patient was hemodynamically stable and bilateral upper extremity blood pressures were similar. There was no mediastinal widening on portable chest radiograph. Both contrast CT and retrograde angiography of the aorta failed to identify dissection. Subsequent transesophageal echocardiography demonstrated a Stanford classification type A dissection. This case demonstrates the utility of multiple imaging modalities for identifying aortic dissection in high-risk patients.

Suspected aortic dissection and other aortic disorders: multi-detector row CT in 373 cases in the emergency setting

PURPOSE

To retrospectively review the authors' experience with multi-detector row computed tomography (CT) for detection of aortic dissection in the emergency setting.

MATERIALS AND METHODS

The investigation was institutional review board approved, did not require informed patient consent, and was HIPAA compliant. In 373 clinical evaluations in the emergency setting, 365 patients suspected of having aortic dissection and/or other aortic disorders underwent multidetector CT. Criteria for acute aortic disorder were confirmed by using surgical and pathologic diagnoses or findings at clinical follow-up and any subsequent imaging as the reference standard. Positive cases were characterized according to type of disorder interpreted. Resulting sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated by using two-way contingency tables. All cases found to be negative for acute aortic disorders were grouped according to alternative CT findings.

RESULTS

Sixty-seven (18.0%) of the 373 cases were interpreted as positive for acute aortic disorder. One hundred twelve acute aortic disorders were identified in these 67 cases: 23 acute aortic dissections, 14 acute aortic intramural hematomas, 20 acute penetrating aortic ulcers, 44 new or enlarging aortic aneurysms, and 11 acute aortic ruptures. Three hundred five (81.8%) cases were interpreted as negative for acute aortic disorder. In 48 negative cases, multidetector CT depicted alternative findings that accounted for the clinical presentation. Of these, three included both acute aortic disorders and alternative findings, and 45 included only alternative findings. One (0.3%) case was indeterminate for acute aortic disorder. Overall, 112 findings were interpreted as positive for acute aortic disorder, an alternative finding, or both at CT. No interpretations were false-positive, one was false-negative, 67 were true-positive, and 304 were true-negative. Sensitivity, specificity, PPV, NPV, and accuracy were 99% (67 of 68), 100% (304 of 304), 100% (67 of 67), 99.7% (304 of 305), and 99.5% (371 of 373), respectively.

CONCLUSION

The positivity rate for acute aortic dissection or other acute aortic disorder in 373 cases examined at multi-detector row CT was 18.0%.

Aortic dissection in a young man with immune thrombocytopenic purpura

A 36-year-old man who presented with epigastric and back pain was subsequently diagnosed with aortic dissection. Our patient lacked classic risk factors that would have predisposed him to develop this condition at a young age. He did, however, suffer from untreated, chronic immune thrombocytopenic purpura (ITP) and had a platelet count less than 20,000/mm(3) on admission. We postulate that the thrombocytopenia led to spontaneous hemorrhage within the vasa vasorum of the aorta and the subsequent development of aortic dissection. Chronic ITP has been associated with an increased risk of intracranial hemorrhage but, to our knowledge, has not been reported to be associated with aortic dissection. We encourage clinicians to be aware of this potential risk factor for aortic dissection.

D-dimers in the emergency department evaluation of aortic dissection

Aortic dissection (AD) is the most common acute aortic condition requiring urgent surgery. AD, if not diagnosed in the emergency department (ED), is frequently fatal. AD is a difficult antemortem diagnosis.

OBJECTIVES

To determine if acute AD is associated with an elevation of fibrin degradation products, D-dimers.

METHODS

This was a retrospective chart review of patients diagnosed as having AD in the ED in whom a D-dimer determination was obtained in the ED, prior to any therapeutic intervention. The study was conducted in an urban Level I trauma center between October 1996 and September 2000. Exclusion criteria were referred patients with known diagnosis of AD. The D-dimer assay used was the semiquantitative latex agglutination assay, with a normal range up to 0.5 micro g/mL.

RESULTS

One hundred fifty-six patients were diagnosed as having AD in the ED. Seven patients had a D-dimer assay during their workup. All seven had a positive test.

CONCLUSIONS

All seven patients with an AD who had D-dimer assays performed in the ED had positive results by latex agglutination.

Difficulties in the diagnosis of acute aortic dissection

A69-year-old woman with known hypertension presented to hospital with sudden onset severe central chest pain radiating between her shoulder blades and into her abdomen. This was associated with loss of power and sensation in her left leg lasting for 30 minutes. She complained of residual discomfort between her scapulae. Examination revealed a well-looking woman with unequal blood pressures in both arms: right 140/70 mmHg, left 100/80 mmHg, a pulse rate of 84/min and no audible murmurs. There was no vascular or neurological deficit in either leg. 12-lead electrocardiogram showed left ventricular hypertrophy by voltage criteria and chest radiograph was normal. Urgent spiral computed tomography of the chest and abdomen showed an extensive type A dissection of her aorta from her aortic valve to the abdominal aortic bifurcation (Figure 1). Despite attempts at haemodynamic resuscitation, she died in the ambulance en route to the regional cardiothoracic centre. Post mortem revealed a tense haemopericardium.

How many hospital beds?

For many years, average bed occupancy level has been the primary measure that has guided hospital bed capacity decisions at both policy and managerial levels. Even now, the common wisdom that there is an excess of beds nationally has been based on a federal target of 85% occupancy that was developed about 25 years ago. This paper examines data from New York state and uses queueing analysis to estimate bed unavailability in intensive care units (ICUs) and obstetrics units. Using various patient delay standards, units that appear to have insufficient capacity are identified. The results indicate that as many as 40% of all obstetrics units and 90% of ICUs have insufficient capacity to provide an appropriate bed when needed. This contrasts sharply with what would be deduced using standard average occupancy targets. Furthermore, given the model's assumptions, these estimates are likely to be conservative. These findings illustrate that if service quality is deemed important, hospitals need to plan capacity based on standards that reflect the ability to place patients in appropriate beds in a timely fashion rather than on target occupancy levels. Doing so will require the collection and analysis of operational data-such as demands for and use of beds, and patient delays--which generally are not available.

Aortic dissection

The presentation of aortic dissection in the emergency department may be more subtle than the classic description of a shocked patient with "ripping" chest pain. The epidemiology, variation in presentation, investigation, and management of aortic dissection are reviewed.

Transesophageal echocardiography for ascending aortic dissection: is it enough for surgical intervention?

BACKGROUND

Acute ascending aortic dissection is a surgical emergency that requires expeditious diagnosis and prompt surgical intervention. In many centers, transesophageal echocardiography (TEE) is the test of choice on which surgical decisions are based. Echocardiographic false-positive diagnoses are rare but can occur with potentially severe consequences.

CASE REPORT

Two clinical cases where ascending aortic dissections were falsely diagnosed by TEE are presented.

DISCUSSION

Recent literature comparing the diagnostic accuracy of TEE and other imaging techniques are reviewed. Anatomical limitations of TEE and potential causes of false-positive results are discussed. Multiplane probe reduces, but does not eliminate, the occurrence of false-positive findings. To improve diagnostic specificity without undue delays in the course of clinical decision making, we recommend dividing positive TEE findings into "definite" and "probable" categories. Such subclassification is helpful in identifying cases where additional confirmatory tests are desirable in situations of uncertain diagnosis.

Prevalence and structure of ultrasound curricula in emergency medicine residencies

Emergency medicine (EM) residency program directors were surveyed to determine the presence and structure of curricula for teaching ultrasound to EM residents. For those EM programs without an ultrasound curriculum (USC), information was requested on plans to implement one within the next 12 months. Ninety of 116 (78%) EM programs replied to the survey. One-half of EM residencies surveyed have USCs, and another 30% plan to implement one in the near future.