Diagnosing acute aortic syndrome: a Canadian clinical practice guideline

Performance and costs of rule-out protocols for acute aortic syndromes: analysis of pooled prospective cohorts

BACKGROUND

Acute aortic syndromes (AAS) are deadly conditions causing unspecific symptoms, such as chest/abdominal/back pain, syncope and neurological deficit. They are diagnosed with computed tomography angiography (CTA), but the patient selection is challenging. To support physicians and standardize management, protocols combining a clinical score with D-dimer (DD) have been developed. However, direct comparison of their diagnostic performance and cost-effectiveness is lacking.

METHODS

We used individual patient data from 3 prospective diagnostic studies of patients with suspected AAS, enrolled in 12 centers from 5 countries. Diagnostic accuracy, failure rate and costs were calculated for 5 protocols, applying 3 scores (aortic dissection detection [ADD], AORTAs and Canadian) and 2 DD thresholds (500 ng/mL [DD500], age-adjusted [DDage]). Costs were estimated using Italian and German reimbursements.

RESULTS

Among 4907 patients, 506 (10.3 %) had an AAS. The sensitivity of the diagnostic protocols ranged from 97.6 % for Canadian/DD500 to 99.4 % for AORTAs/DD500 or DDage (P = 0.022). The specificity was lowest for AORTAs/DD500 (46.8 %; P < 0.001 vs AORTAs/DD500) and highest for ADD/DDage (61.5 %; P < 0.001). The number of potential AAS misses was 4-fold higher with Canadian/DD500 vs AORTAs/DD500 or DDage. The net clinical benefit was highest for ADD/DDage. All protocols reduced CTA exams and costs over a CTA-to-all strategy. Numbers of predicted CTA exams and costs per 100 patients were lowest for ADD/DDage (447 CTAs, 34,366 EUR) and highest (579 CTAs, 43,628 EUR) for AORTAs/DD500.

CONCLUSIONS

Guideline-compliant clinical score/DD based protocols are highly sensitive. Differences in specificity and efficiency are present. Data may guide decision-making based on policies and resources.

Prognostic Value of Biomarkers in Acute Aortic Dissection: Analysis of Clinical Outcomes and Mortality

Introduction: Acute aortic dissection (AAD) is a severe condition requiring immediate diagnosis and treatment to reduce high mortality rates. This study investigates laboratory markers that may support the diagnostic process and predict surgical outcomes and mortality in AAD patients. Materials and Methods: This retrospective study analyzed data from 85 patients diagnosed with AAD in an emergency setting. Patients over 18 years of age with a diagnosis of acute dissection were included. Key laboratory and clinical parameters were examined to determine their association with mortality and the likelihood of surgical intervention. Results: The study found that younger patients were more likely to undergo surgery, while parameters such as white blood cells (WBCs), neutrophil, and lymphocyte counts were elevated in those undergoing surgery. Mortality predictors included elevated mean platelet volume (MPV), low pH, bicarbonate (HCO3), and base deficit levels. Each unit increase in MPV was associated with a threefold increase in mortality risk, and DeBakey Type 1 patients exhibited the highest MPV levels. Discussion: WBC and MPV values were linked with surgical and mortality outcomes, respectively. Blood gas analysis parameters, particularly HCO3 and base deficit levels, were significant mortality predictors, underscoring the importance of metabolic markers in AAD assessment. The findings suggest that incorporating these laboratory parameters into diagnostic and treatment decisions could improve AAD management.

Decision analytical modelling of strategies for investigating suspected acute aortic syndrome

BACKGROUND

Acute aortic syndrome (AAS) requires urgent diagnosis with computed tomographic angiography (CTA). Diagnostic strategies need to weigh the benefits of detecting AAS against the costs of using CTA with a low yield of AAS when the prevalence of AAS is low. We aimed to estimate the cost-effectiveness of diagnostic strategies using clinical probability scoring and D-dimer to select patients with potential symptoms of AAS for CTA.

METHODS

We developed a decision analytical model to simulate the management of patients attending hospital with possible AAS. We modelled diagnostic strategies that used the Aortic Dissection Detection Risk Score (ADD-RS) and D-dimer to select patients for CTA. We used estimates from our meta-analysis, existing literature and clinical experts to model the consequences of diagnostic strategies on survival, health utility, and health and social care costs. We estimated the incremental cost per quality-adjusted life-years gained by each strategy compared with the next most effective alternative on the efficiency frontier.

RESULTS

A strategy based on the Canadian guideline (CTA if ADD-RS>1 or ADD-RS=1 with D-dimer >500 ng/mL) is cost-effective but would result in high rates of CTA if applied to an unselected population (AAS prevalence 0.26%). The strategy is also cost-effective and would result in lower rates of CTA if applied to a more selected population, such as those with a non-zero clinical suspicion of AAS (prevalence 0.61%). For patients currently receiving CTA, using ADD-RS>1 or D-dimer >500 ng/mL to select patients for CTA is cost-effective.

CONCLUSIONS

A strategy using ADD-RS>1 or ADD-RS=1 with D-dimer >500 ng/mL to select patients for CTA appears cost-effective but primary research is required to evaluate this strategy in practice and determine how suspicion of AAS is identified.

Twenty-five years of observations from the International Registry of Acute Aortic Dissection (IRAD) and its impact on the cardiovascular scientific community

OBJECTIVE

The International Registry of Acute Aortic Dissection (IRAD) celebrated its 25th anniversary in January 2021. This study evaluated IRAD's role in promoting the understanding and management of acute aortic dissection (AD) over these years.

METHODS

IRAD studies were identified, analyzed, and ranked according to their citations per year (c/y) to determine the most-cited IRAD studies and topics. A systematic search of the literature identified cardiovascular guidelines on the diagnosis and management of acute AD. Consequently, IRAD's presence and impact were quantified using these documents.

RESULTS

Ninety-seven IRAD studies were identified, of which 82 obtained more than 10 cumulative citations. The median c/y index was 7.33 (25th-75th percentile, 4.01-16.65). Forty-two studies had a greater than median c/y index and were considered most impactful. Of these studies, most investigated both type A and type B AD (n = 17, 40.5%) and short-term outcomes (n = 26, 61.9%). Nineteen guideline documents were identified from 26 cardiovascular societies located in Northern America, Europe, and Japan. Sixty-nine IRAD studies were cited by these guidelines, including 38 of the 42 most-impactful IRAD studies. Among them, partial thrombosis of the false lumen as a predictor of postdischarge mortality and aortic diameters as a predictor of type A occurrence were determined as most-impactful specific IRAD topics by their c/y index.

CONCLUSIONS

IRAD has had and continues to have an important role in providing observations, credible knowledge, and research questions to improve the outcomes of patients with acute AD.

Diagnosis and management of acute aortic dissection in the emergency department

Acute aortic dissection is often misdiagnosed as a result of its atypical presentations. It affects 4000 patients a year in the UK of all ages, not just older patients, with increasing numbers of cases expected in the future because of the ageing population. Dissection of the aortic wall leads to sudden, severe pain, and commonly end-organ symptoms which must be recognised. Acute aortic dissection can be challenging to diagnose in the emergency department because of the multitude of possible presentations and the need for selective testing with Computed Tomography Angiography (CTA). Clinicians often miss acute aortic dissection because it is not considered in the differential diagnosis, and the challenge lies in identifying acute aortic dissection in a sea of complaints of chest, back and abdominal pain. There are several ways to improve diagnosis, including awareness campaigns, better education about patients in which to consider acute aortic dissection, and improved detection strategies including which patients should receive CTA. Clinical decision tools and biomarkers could help, but further research is required and is a research focus in emergency medicine. Once diagnosed, blood pressure control, analgesia and urgent surgery or transfer to enable this to occur with minimal delay is required.

Mortality and risk factors associated with misdiagnosis of acute aortic syndrome in Ontario, Canada: a population-based study

INTRODUCTION

Acute aortic syndrome (AAS) is a life-threatening aortic emergency. It describes three diagnoses: acute aortic dissection, acute intramural haematoma and penetrating atherosclerotic ulcer. Unfortunately, there are no accurate estimates of the miss rate for AAS, risk factors for missed diagnosis or its effect on outcomes.

METHODS

A population-based retrospective cohort study of anonymously linked data for residents of Ontario, Canada, was carried out. Incident cases of AAS were identified between 2003 and 2018 using a validated algorithm based on ICD codes and death. Before multivariate modelling, all categorical variables were analysed for an association with missed AAS diagnosis using χ2 tests. These preliminary analyses were unadjusted for clustering or any covariates. Finally, we performed multilevel logistic regression analysis using a generalised linear mixed model approach to model the probability of a missed case occurring.

RESULTS

There were 1299 cases of AAS (age mean (SD) 68.03±14.70, woman 500 (38.5%), rural areas (n=111, 8.55%)) over the study period. Missed cases accounted for 163 (12.5%) of the cohort. Mortality (non-missed AAS 59.7% vs missed AAS 54.6%) and surgical intervention (non-missed AAS 31% vs missed AAS 30.7%) were similar in missed and non-missed cases. However, lower acuity (Canadian triage acuity scale >2 (OR 2.45 95% CI 1.71 to 3.52) (the scale is from 1 to 5, with 1 indicating high acuity) had a higher odds of being a missed case and non-ambulatory presentation (OR 0.47 95% CI 0.33 to 0.67) and presenting to a teaching (OR 0.60 95% CI 0.40 to 0.90)) or cardiac centre (OR 0.41 95% CI 0.27 to 0.62) were associated with a lower odds of being a missed case.

CONCLUSIONS

The high rate of misdiagnosis has remained stable for over a decade. Non-teaching and non-cardiac hospitals had a higher incidence of missed cases. Mortality and rates of surgery were not associated with a missed diagnosis of AAS. Educational interventions should be prioritised in non-teaching hospitals and non-cardiac centres.

Diagnosis of Acute Aortic Syndrome in the Emergency Department (DAShED) study: an observational cohort study of people attending the emergency department with symptoms consistent with acute aortic syndrome

BACKGROUND

The diagnosis of acute aortic syndrome (AAS) is commonly delayed or missed in the ED. We describe characteristics of ED attendances with symptoms potentially associated with AAS, diagnostic performance of clinical decision tools (CDTs) and physicians and yield of CT aorta angiogram (CTA).

METHODS

This was a multicentre observational cohort study of adults attending 27 UK EDs between 26 September 2022 and 30 November 2022, with potential AAS symptoms: chest, back or abdominal pain, syncope or symptoms related to malperfusion. Patients were preferably identified prospectively, but retrospective recruitment was also permitted. Anonymised, routinely collected patient data including components of CDTs, was abstracted. Clinicians treating prospectively identified patients were asked to record their perceived likelihood of AAS, prior to any confirmatory testing. Reference standard was radiological or operative confirmation of AAS. 30-day electronic patient record follow-up evaluated whether a subsequent diagnosis of AAS had been made and mortality.

RESULTS

5548 patients presented, with a median age of 55 years (IQR 37-72; n=5539). 14 (0.3%; n=5353) had confirmed AAS. 10/1046 (1.0%) patients in whom the ED clinician thought AAS was possible had AAS. 5/147 (3.4%) patients in whom AAS was considered the most likely diagnosis had AAS. 2/3319 (0.06%) patients in whom AAS was considered not possible did have AAS. 540 (10%; n=5446) patients underwent CT, of which 407 were CTA (7%). 30-day follow-up did not reveal any missed AAS diagnoses. AUROC (area under the receiver operating characteristic) curve for ED clinician AAS likelihood rating was 0.958 (95% CI 0.933 to 0.983, n=4006) and for individual CDTs were: Aortic Dissection Detection Risk Score (ADD-RS) 0.674 (95% CI 0.508 to 0.839, n=4989), AORTAs 0.689 (95% CI 0.527 to 0.852, n=5132), Canadian 0.818 (95% CI 0.686 to 0.951, n=5180) and Sheffield 0.628 (95% CI 0.467 to 0.788, n=5092).

CONCLUSION

Only 0.3% of patients presenting with potential AAS symptoms had AAS but 7% underwent CTA. CDTs incorporating clinician gestalt appear to be most promising, but further prospective work is needed, including evaluation of the role of D-dimer.

TRIAL REGISTRATION NUMBER

NCT05582967; NCT05582967.

Can you accurately rule out acute aortic syndrome by restricting imaging of the aorta to the area of the patient's pain?

BACKGROUND

Acute aortic syndrome (AAS) is a life-threatening condition necessitating timely and accurate diagnosis for appropriate treatment. Currently, the only way to rule out the diagnosis is advanced imaging. The most accessible is computed tomography of the entire aorta. Most scans are negative, exposing patients to radiation, increased time in the emergency department (ED), and non-significant incidental findings. This study investigated whether restricting imaging to the area of aortic-related pain accurately rules out AAS.

METHODS

A health records review was conducted on consecutive cases from three academic EDs between 2015 and 2020. Data were extracted and verified from multiple sources. Participants included adults diagnosed with AAS based on radiological evidence. The diagnostic performance of the restricted imaging strategy was assessed; sensitivity and likelihood ratios with 95% confidence intervals were calculated.

RESULTS

Data from 149 cases of AAS were collected, with the majority presenting with chest pain (46%) or abdominal pain (24%). The restricted imaging strategy demonstrated a sensitivity of 96% (95% CI 91.4-98.5%) in ruling out AAS. In a subset of patients with systolic blood pressure > 90 mmHg and without aortic aneurysm/repair (n = 86), the sensitivity was 100% (95% CI 96-100%).

CONCLUSION

Restricting imaging to the area of pain in hemodynamically stable patients without known aortic aneurysm provides a highly sensitive approach to ruling out AAS.

Improvement in the management of suspected acute aortic syndrome in the emergency room through a clinical algorithm and study of predictive factors

BACKGROUND AND OBJECTIVE

Acute aortic syndrome (AAS) is uncommon and difficult to diagnose, with great variability in clinical presentation. To develop a computerized algorithm, or clinical decision support system (CDSS), for managing and requesting imaging in the emergency department, specifically computerized tomography of the aorta (CTA), when there is suspicion of AAS, and to determine the effect of implementing this system. To determine the factors associated with a positive radiological diagnosis that improve the predictive capacity of CTA findings.

MATERIALS AND METHODS

After developing and implementing an evidence-based algorithm, we studied suspected cases of AAS. Chi-squared test was used to analyze the association between the variables included in the algorithm and radiological diagnosis, with 3 categories: no relevant findings, positive for AAS, and alternative diagnoses.

RESULTS

130 requests were identified; 19 (14.6%) had AAS and 34 (26.2%) had a different acute pathology. Of the 19 with AAS, 15 had been stratified as high risk and 4 as intermediate risk. The probability of AAS was 3.4 times higher in patients with known aortic aneurysm (P = .021, 95% CI 1.2-9.6) and 5.1 times higher in patients with a new aortic regurgitation murmur (P = .019, 95% CI 1.3-20.1). The probability of having an alternative severe acute pathology was 3.2 times higher in patients with hypotension or shock (P = .02, 95% CI 1.2-8.5).

CONCLUSION

The use of a CDSS in the emergency department can help optimize AAS diagnosis. The presence of a known aortic aneurysm and new-onset aortic regurgitation were shown to significantly increase the probability of AAS. Further studies are needed to establish a clinical prediction rule.

An Evidenced-Based Review of Emergency Target Blood Pressure Management for Acute Aortic Dissection

Objective

To summarize the best evidence of emergency target blood pressure management for acute aortic dissection and provide guidance for evidence-based practice of emergency target blood pressure management.

Methods

According to the "6S" evidence pyramid model, the evidence of emergency target blood pressure management of acute aortic dissection in various foreign databases and websites of professional associations from January 1, 2010, to August 1, 2022, was retrieved, including clinical decision-making, guidelines, expert consensus, systematic reviews, randomized controlled trials, cohort studies, and case series. Two researchers used the corresponding document quality evaluation tools to evaluate the documents and extracted and summarized the evidence of documents above grade B.

Results

A total of 17 articles were included, including 6 clinical decision-making articles, 5 guidelines, 2 expert consensus articles, 1 systematic review article, 1 randomized controlled trial article, 1 cohort study article, and 1 case series article, forming 36 best evidences, including 9 topics, which are target value setting, management strategy, disease observation, medical history collection, monitoring methods, vasoactive drugs, nonvasoactive drugs, related examinations, and patient education.

Conclusion

The best evidence summarized provides a reference for doctors and nurses in the emergency department to manage the emergency target blood pressure of patients with acute aortic dissection. It is recommended that doctors and nurses in the emergency department follow the best evidence summarized to develop individualized target blood pressure management plan for patients.

Evaluation of the Canadian Clinical Practice Guidelines Risk Prediction Tool for Acute Aortic Syndrome: The RIPP Score

Introduction

Acute aortic syndrome (AAS) is a rare clinical syndrome with a high mortality rate. The Canadian clinical practice guideline for the diagnosis of AAS was developed in order to reduce the frequency of misdiagnoses. As part of the guideline, a clinical decision aid was developed to facilitate clinician decision-making (RIPP score). The aim of this study is to validate the diagnostic accuracy of this tool and assess its performance in comparison to other risk prediction tools that have been developed.

Methods

This was a historical case-control study. Consecutive cases and controls were recruited from three academic emergency departments from 2002-2020. Cases were identified through an admission, discharge, or death certificated diagnosis of acute aortic syndrome. Controls were identified through presenting complaint of chest, abdominal, flank, back pain, and/or perfusion deficit. We compared the clinical decision tools' C statistic and used the DeLong method to test for the significance of these differences and report sensitivity and specificity with 95% confidence intervals.

Results

We collected data on 379 cases of acute aortic syndrome and 1340 potential eligible controls; 379 patients were randomly selected from the final population. The RIPP score had a sensitivity of 99.7% (98.54-99.99). This higher sensitivity resulted in a lower specificity (53%) compared to the other clinical decision aids (63-86%). The DeLong comparison of the C statistics found that the RIPP score had a higher C statistic than the ADDRS (-0.0423 (95% confidence interval -0.07-0.02); P < 0.0009) and the AORTAs score (-0.05 (-0.07 to -0.02); P = 0.0002), no difference compared to the Lovy decision tool (0.02 (95% CI -0.01-0.05 P < 0.25)) and decreased compared to the Von Kodolitsch decision tool (0.04 (95% CI 0.01-0.07 P < 0.008)).

Conclusion

The Canadian clinical practice guideline's AAS clinical decision aid is a highly sensitive tool that uses readily available clinical information. It has the potential to improve diagnosis of AAS in the emergency department.

Why do emergency department clinicians miss acute aortic syndrome? A case series and descriptive analysis

Objectives: To understand why the diagnosis of AAS is missed in the ED, and to characterise the presenting features of cases in which a diagnosis of AAS was missed. Methods: A retrospective case series cohort study was performed, identifying and analysing cases where AAS was misdiagnosed in three UK EDs between 1st January 2011 and 31st December 2020. Results: 43 cases were included, 22 of which were type A aortic dissections. The most common incorrect presumed diagnoses made were acute coronary syndrome (28%), pulmonary embolism (12%) and ‘non-specific chest pain’ (12%). In 31 cases (72%) there was no evidence from the notes that the clinician had considered AAS in the differential diagnosis. In 10 cases (23%), AAS was considered, but the clinician was falsely reassured by atypical or resolved symptoms, clinical examination, or normal chest x-ray. Conclusions: ED clinicians may miss AAS by not considering it as a possibility, being falsely reassured by atypical or resolved symptoms, or mistaking it for other more common conditions.  Further prospective work is necessary to establish the role of diagnostic aids and biomarkers in UK EDs.

Acute Aortic Syndrome in Aotearoa New Zealand: What Does It Mean for Māori?

There is increasing evidence that New Zealand has a relatively high incidence of acute aortic syndrome (AAS), which has been attributed to the disproportionately high incidence of AAS among the indigenous Māori population. There is growing interest in the use of risk-stratification tools to help clinicians determine which patients with suspected AAS should proceed to advanced imaging. The aortic dissection detection risk score has been proposed as a novel tool for excluding AAS when coupled with a serum D-dimer <500 ng/mL. However, its use in Māori has not specifically been evaluated. A review of AAS in Māori is herein undertaken with a call made for further work to clarify the outcomes and incidences in Māori. Given that Māori ethnicity is a high-risk criterion for AAS, it is recommended that, until the rule-out test is validated in Māori, clinicians have a low threshold for excluding AAS with advanced imaging.

Epidemiology, mortality and miss rate of acute aortic syndrome in Ontario, Canada: a population-based study

INTRODUCTION

Acute aortic syndrome (AAS) is a life-threatening emergency. It describes three distinct diagnoses: acute aortic dissection, acute intramural hematoma and penetrating atherosclerotic ulcer. There are currently no accurate estimates for incidence, mortality or misdiagnosis. Our objectives were to determine the incidence, mortality and miss rate of acute aortic syndrome in the emergency department (ED).

METHODS

A population-based retrospective cohort study of anonymously linked data for residents of Ontario, Canada, was carried out. Incident cases of acute aortic syndrome were identified between 2003 and 2018 using a validated algorithm based on ICD-10 codes and death. Incidence (number of cases/population of Ontario), mortality, and miss rate were calculated. Miss rate was defined as when a patient was seen in the ED within 14 days prior to an acute aortic syndrome diagnosis with a presenting complaint consistent with acute aortic syndrome.

RESULTS

There were 1299 cases of acute aortic syndrome over the study period [age mean (SD) 68.03 ± 14.70; female (n = 500, 38.5%); rural areas (n = 111, 8.6%)]. The overall annual incidence for acute aortic syndrome was 0.61 per 100,000. One year mortality decreased from 47.4 to 29.1%. ED mortality was 14.9%. In the 14 days prior to diagnosis 12.5% of patients were seen in the ED with a presentation consistent with acute aortic syndrome.

CONCLUSIONS

Annual incidence of acute aortic syndrome was found to be lower than other population-based studies. Also, the burden of mortality is seen in the ED. Education initiatives should focus on the identification of acute aortic syndrome in the ED to address mortality and miss rate.

A sinister needle in an enormous haystack: A clinician survey regarding Acute Aortic Syndrome diagnostic practice in United Kingdom Emergency Departments

Acute Aortic Syndrome (AAS) is a life-threatening condition associated with high diagnostic uncertainty. This results in an unacceptable number of missed cases, which contributes to its high mortality. We designed and distributed a survey to Emergency Departments (EDs) across the United Kingdom to establish the standard practice for investigation and diagnosis of AAS across the UK. 56 EDs across the UK responded. The majority of these did not have a formal work-up pathway for AAS. The estimated CT scanning rates and missed cases of AAS were highly variable between departments. This suggests variation in practice and diagnostic uncertainty. Given its time sensitive nature, the need for a more standardised diagnostic pathway for AAS in EDs is evident. This may aid clinicians rule out AAS more safely and reduce the number of missed cases, which would in turn reduce the high morbidity and mortality associated with AAS.

Barriers and facilitators affecting implementation of the Canadian clinical practice guidelines for the diagnosis of acute aortic syndrome

BACKGROUND

Acute aortic syndrome (AAS) is an uncommon, life-threatening emergency that is frequently misdiagnosed. The 2020 Canadian clinical practice guidelines for the diagnosis of AAS incorporate all available evidence into four key recommendations. In order to facilitate the implementation of these recommendations, a clinical decision aid was created. The objective of this study was to identify barriers and facilitators among physicians prior to implementation of the guideline recommendations in a multicentre step wedge cluster randomized control trial.

METHODS

We conducted semi-structured interviews with nine emergency room physicians working at five sites distributed between urban academic and rural settings. We used purposive sampling, contacting physicians until data saturation was reached. Interview questions were designed to understand potential barriers and facilitators to guideline recommendation uptake and use. Responses were analysed according to the Theoretical Domains Framework, and overarching themes describing these barriers and facilitators were identified.

RESULTS

Two themes and six subthemes encompassing 13 theoretical domains were identified. These included clinical decision-making support, awareness of the evidence, social factors, expected consequences, ability of physicians to acquire the necessary data and ease of use. A majority of interviewees anticipated that the guideline recommendations would support clinical decision making and more effectively risk-stratify patients. Other facilitators included endorsement of the guidelines by professional organizations and peers. Barriers to implementation include the fact that laboratory testing and knowledge of the rationale for its use in the investigation of AAS were not widespread. The complexity of the clinical decision aid and concerns about test specificity were also identified as potential barriers to use.

CONCLUSION

Physicians were amenable to using the AAS guideline recommendations to support clinical decision-making and to reduce resource use. A structured intervention should be developed to address the identified barriers and leverage the facilitators in order to ensure successful implementation. Our findings may have implications for the implementation of other guidelines used in emergency departments.

Computed Tomography Angiography Assessment of Acute Aortic Syndromes: Classification, Differentiating Imaging Features, and Imaging Interpretation Pitfalls

An acute aortic syndrome (AAS) is an important life-threatening condition that requires early detection and management. Acute intramural hematoma (IMH), aortic dissection (AD) and penetrating atherosclerotic ulcer (PAU) are included in AAS. ADs can be classified using the well-known Stanford or DeBakey classification systems. However, these classification systems omit description of arch dissections, anatomic variants, and morphologic features that impact outcome. The Society for Vascular Surgery and Society of Thoracic Surgeons (SVS-STS) have recently introduced a classification system that classifies ADs according to the location of the entry tear (primary intimomedial tear, PIT) and the proximal and distal extent of involvement, but does not include description of all morphologic features that may have diagnostic and prognostic significance. This review describes these classification systems for ADs and other AAS entities as well as their limitations. Typical computed tomography angiography (CTA) imaging appearance and differentiating features of ADs, limited intimal tears (LITs), IMHs, intramural blood pools (IBPs), ulcer-like projections (ULPs), and PAUs will be discussed. Furthermore, this review highlights common imaging interpretation pitfalls, what should be included in a comprehensive CTA report, and provides a brief overview of current management options.