Acute Aortic Syndrome Revisited

Authors, Journal, Affiliations, Type, DOI

• Authors: Isidre Vilacosta and J. Alberto San Román (Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid; CIBERCV), with Roberto di Bartolomeo (Bologna), Kim Eagle (Michigan), Anthony Estrera (UTHealth Houston), Christoph Nienaber (Royal Brompton), Hans-Joachim Schäfers (Homburg/Saar), Jae-Kwan Song (Asan Medical Center) and Luis Maroto (Barcelona)
• Journal: Journal of the American College of Cardiology. 2021;78(21):2106–2125
• Type: State-of-the-art review — an argument for a revised definition and a simplified diagnostic algorithm rather than a systematic review
• DOI: https://doi.org/10.1016/j.jacc.2021.09.022

Overview

This review defines acute aortic syndrome as four conditions, not three: classic dissection, intramural haematoma, penetrating aortic ulcer, and incomplete dissection — an intimal tear without a false lumen that the literature has variously called a limited intimal tear or a subtle/discrete dissection. It is the paper that makes incomplete dissection a first-class member of the family and gives it a histological and imaging identity.

Its central practical proposal is a three-step diagnostic algorithm that replaces the denser guideline flowcharts: (1) pretest probability from risk conditions, pain characteristics and examination findings; (2) ECG, chest radiograph, troponin and D-dimer, where the triad of aortic pain with a normal ECG and normal troponin but a raised D-dimer is the alerting pattern; (3) CT of the entire aorta, with focused bedside echocardiography as an adjunct. It also argues that AAS care should be centralised in high-volume "aorta centres" reached through an "aorta code", on the grounds that the volume–outcome relationship is driven by individual surgeon experience rather than the institution's size alone.

Keywords

Acute aortic syndrome · classic dissection · intramural haematoma · penetrating aortic ulcer · incomplete dissection · intramural blood pool · ulcer-like projection · D-dimer · ADD-RS · aorta code · aorta centre · malperfusion · type A IMH · TEVAR

Key Takeaways

The four constituents

• Classic dissection: intimo-medial tear with a false lumen within the media; dissection plane consistently in the outer media at the level of the vasa vasorum network, with elastic fibre fragmentation and mucoid matrix accumulation.
• Intramural haematoma: historically "dissection without intimal tear", arising from vasa vasorum rupture. The authors argue for a single mechanism — IMH being a classic dissection with an acutely thrombosed false lumen — pointing to tears found at surgery that imaging had missed.
• Penetrating aortic ulcer: ulceration of an atherosclerotic plaque through the internal elastic lamina, usually in the descending aorta, usually with local intramedial haemorrhage; may rupture, pseudoaneurysm, or evolve into dissection.
• Incomplete dissection: laceration of intima and subjacent media without significant intramedial haematoma and no false lumen; eccentric wall bulge and subadventitial haematoma. Represents approximately 5% of all AAS and is mostly ascending.
• The lesions appear synchronously or metachronously — any one can progress to rupture, especially in the first week.

Epidemiology

• Incidence of classic dissection 6–7.2 per 100,000 patient-years (Swedish and British cohorts); 7.7 per 100,000 person-years for all acute aortic lesions (Olmsted County).
• Stanford type A predominates among classic and incomplete dissection; type B among IMH and PAU.
• Men ~2-fold more common; women present later, in worse condition, with more coma and tamponade, and 30–50% of patients with type A dissection die before reaching hospital — so hospital registries underestimate incidence.
• In-hospital mortality for dissection 26% in the largest US database, unchanged between 2012 and 2016 despite rising admissions.

The three-step diagnostic algorithm

• Step 1 — pretest probability. ADD-RS assigns one point each for high-risk conditions, high-risk pain and high-risk examination findings. A score of 0 does not exclude AAS, and the score has poor specificity at ≥1.
• Hypertension is absent from the ADD-RS despite being the most frequent risk factor, present in 86% of those who later develop dissection; the authors argue for adding it.
• Step 2 — ECG, troponin, D-dimer and chest radiograph. D-dimer is highly sensitive, correlates with lesion extent and is higher in classic dissection than IMH; a value >1,600 ng/mL raises the likelihood substantially. A normal chest radiograph is common and does not exclude AAS.
• Step 3 — CT of the entire aorta from cervical branches to iliofemoral arteries, with and without contrast and with ECG gating. Focused TTE helps but a normal TTE does not exclude AAS; TEE when CT is non-diagnostic; MRI has no practical role acutely.
• Acute coronary syndrome is the commonest misdiagnosis. Troponin positivity does not exclude dissection — it may rise from coronary ostial involvement or acute regurgitation — and must not defer imaging where suspicion is high.

Imaging mimics to know

Management

• Medical targets in the hyperacute phase: blood pressure 100–120 mmHg, pulse ≤60/min, and analgesia. IV beta-blockers given simultaneously with other antihypertensives; sedatives always considered.
• Type A: emergency open repair; ascending and hemiarch replacement with valve resuspension in most; composite valve graft (modified Bentall–de Bono) when the root is involved or there is connective tissue disease; hemiarch with open distal anastomosis is the standard, with total arch and frozen elephant trunk reserved for arch tears, arch dilatation or branch dissection.
• Type B: best medical therapy for uncomplicated; TEVAR for complicated. High-risk features prompting consideration of repair in uncomplicated disease include total aortic diameter >44 mm, false lumen >22 mm, a large proximal entry tear, refractory pain and refractory hypertension.
• Type A IMH: Western and Asian guidelines disagree. The authors propose medical therapy with a watch-and-wait strategy only in patients without risk factors — no ulcer-like projection and aortic diameter <50 mm.
• Type B IMH: medical first; TEVAR for expansion, progressive dilation, periaortic haematoma or localised dissection.
• Type B PAU: TEVAR for symptomatic, complicated or large lesions.

Prevention

• Family history is a strong risk factor; imaging and genetic screening of relatives is advisable.
• Many type A dissections occur below 55 mm, so diameter alone is an inadequate trigger — only about 20% of AAS happen above 55 mm.
• Fluoroquinolones are associated with increased risk of dissection and aneurysm and should be avoided where an alternative exists.

Limitations of the document

• The three-step algorithm has not been prospectively validated, and the authors say so.
• The single-mechanism account of IMH is a hypothesis advanced against the prevailing vasa vasorum model; it is supported by surgical and histological series, not by outcome data, and it changes practice only marginally either way.
• Incomplete dissection is not a term used by either major guideline, which continue to describe three constituents. The wiki therefore carries two overlapping vocabularies.
• The management recommendations are narrative and ungraded, with no COR/LOE scheme — they should not be read as equivalent in weight to a guideline recommendation.
• Epidemiology is developed-world and registry-based, with acknowledged under-ascertainment of prehospital deaths.

Key Concepts Mentioned

concepts/Acute-Aortic-Syndrome · concepts/Acute-Aortic-Syndrome · concepts/Thoracic-Aortic-Aneurysm · concepts/Hypertensive-Crisis · entities/Acute-Coronary-Syndrome · concepts/Cardiac-Tamponade · concepts/Cardiogenic-Shock

Key Entities Mentioned

IRAD (International Registry of Acute Aortic Dissection) · ADD-RS · AORTAs score · aorta code · aorta centre

Wiki Pages Updated

• concepts/Acute-Aortic-Syndrome — created and given the diagnostic algorithm
• concepts/Acute-Aortic-Syndrome — updated
• index — hub entry added