Acute aortic dissection — structured viva

Branch A — Definitions and classification

Examiner: What is an acute aortic syndrome, and how do you classify a dissection?

Strong answer:

• European Society of Cardiology (ESC) 2024 defines acute aortic syndromes (AAS) as life-threatening emergencies including classic acute aortic dissection, intramural haematoma (IMH), penetrating atherosclerotic ulcer (PAU), aortic pseudo-aneurysm and traumatic aortic injury.^[1]
• Stanford type A involves the ascending aorta irrespective of the site of the intimal tear; type B does not, including dissections that involve the arch but spare the ascending aorta (American College of Cardiology/American Heart Association (ACC/AHA) 2022).^[2]
• DeBakey type I starts in the ascending aorta and propagates to the arch and typically the descending aorta; type II is confined to the ascending aorta; type IIIa is confined to the descending thoracic aorta and IIIb extends below the diaphragm (ACC/AHA 2022).^[2]
• By time from symptom onset, ESC 2024 divides AAS into hyperacute (under 24 h), acute (1–14 days), subacute (15–90 days) and chronic (over 90 days).^[1]

Follow-up: What does the Type Entry Malperfusion (TEM) classification add?^[1]

• ESC 2024 describes TEM (Type Entry Malperfusion) as a recently proposed European update of the Stanford classification that combines the type of dissection, its entry site and the presence of malperfusion, giving greater prognostic insight; it is recommended by the European Association for Cardio-Thoracic Surgery.^[1]
• The TEM malperfusion grades (ESC 2024 Figure 29) are M0, no malperfusion; M1, coronary; M2, supra-aortic; M3, spinal, visceral, iliac.^[1]

Branch B — Diagnosis

Examiner: A patient has sudden chest and back pain. How do you decide whether to scan for dissection?

Strong answer:

• ESC 2024 recommends a multiparametric algorithm for ruling AAS in or out using the aortic dissection detection-risk score (ADD-RS) in patients with clinical features compatible with possible AAS (Class I, Level B).^[1]
• The ADD-RS scores 1 point each for a high-risk condition (e.g. Marfan syndrome, family history of aortic disease, known aortic valve disease, recent aortic manipulation, known aortic aneurysm), a high-risk pain feature and a high-risk examination feature.^[1]
• ADD-RS 2 or more is high risk and goes to cardiovascular computed tomography (CCT) from neck to pelvis without delay and/or focused transthoracic echocardiography (TTE) plus electrocardiogram (ECG); below 2, the ESC pathway is ECG to exclude ST-elevation myocardial infarction (STEMI), then chest X-ray, laboratory tests and point-of-care ultrasound if available.^[1]
• Footnote a of ESC 2024 Figure 30, attached to the first step, to the ADD-RS box and to the focused TTE of the high-risk branch, reads: in haemodynamically unstable patients, consider TTE and/or transoesophageal echocardiography (TOE) as first-line imaging technique, depending on local expertise and availability.^[1]
• In suspected AAS, ECG-gated CCT from neck to pelvis is recommended as the first-line imaging technique (ESC 2024 Class I, Level C); ACC/AHA 2022 recommends computed tomography (CT) for initial diagnostic imaging in suspected AAS (class of recommendation [COR] 1, level of evidence [LOE] C-LD).^[1][2]

Follow-up: What is the place of D-dimer?^[1][2]

• ESC 2024: when D-dimer is below 500 ng/mL, dissection is unlikely, but awaiting laboratory results should not delay imaging if the probability of dissection is high.^[1]
• ACC/AHA 2022: a non-elevated D-dimer (below 500 ng/mL) makes the diagnosis unlikely in patients with a low previous probability of AAS.^[2]

Branch C — The first hour

Examiner: CT shows a dissection. What do you do while the team assembles?

Strong answer:

• ESC 2024 recommends immediate anti-impulse treatment targeting systolic blood pressure (SBP) below 120 mmHg and heart rate 60 beats per minute (b.p.m.) or less, with higher mean arterial pressure maintained in spinal ischaemia or concomitant brain injury (Class I, Level B).^[1]
• Intravenous beta-blockers (e.g. labetalol or esmolol) are recommended as first-line agents, and intravenous vasodilators (e.g. dihydropyridine calcium blockers or nitrates) could be added if necessary (Class I, Level B); a non-dihydropyridine calcium blocker should be considered if beta-blockers are contraindicated (Class IIa, Level B).^[1]
• Invasive monitoring with an arterial line, continuous three-lead ECG recording and admission to an intensive care unit (Class I, Level B), and adequate pain control to achieve the targets (Class I, Level C), are recommended.^[1]
• ACC/AHA 2022 says patients with AAS should be treated to an SBP below 120 mm Hg or the lowest blood pressure (BP) that maintains adequate end-organ perfusion, and to a target heart rate of 60 to 80 bpm (b.p.m.) (COR 1, LOE C-LD).^[2]

Follow-up: Why not start with a vasodilator?^[2]

• ACC/AHA 2022 says vasodilators should be avoided as initial treatment, before beta-blockers or calcium channel blockers, because of the potential for compensatory tachycardia; ESC 2024 gives rate-controlling agents first to avoid reflex tachycardia.^[2][1]

Branch D — Type A

Examiner: It is type A. What now, and what do the guidelines say about patients who might not be offered surgery?

Strong answer:

• Emergency surgical consultation and evaluation and immediate surgical intervention are recommended in acute type A dissection (ESC 2024 Class I, Level B), and in suspected or confirmed acute type A dissection (ACC/AHA 2022 COR 1, LOE B-NR).^[1][2]
• ESC 2024 says all patients with acute type A dissection should receive surgical treatment; cardiogenic shock from tamponade, malperfusion of the coronary, mesenteric, lower-limb, renal or cerebral circulation, and coma are major predictors of post-operative mortality.^[1]
• Age per se should not be considered an exclusion criterion for surgery (ESC 2024); ACC/AHA 2022 notes that, with significant contraindications such as frailty, clinical judgement may favour medical management.^[1][2]
• Transfer from a low- to a high-volume aortic centre with the presence of a multidisciplinary team should be considered to improve survival if it can be accomplished without significant delay in surgery (ESC 2024 Class IIa, Level B).^[1]

Follow-up: What does ESC 2024 recommend for the root and the arch?^[1]

• With a partially dissected root but no significant aortic valve leaflet pathology, aortic valve resuspension is recommended over valve replacement (ESC 2024 Class I, Level B).^[1]
• With extensive destruction of the root, a root aneurysm or a known genetic aortic disorder, root replacement with a mechanical or biological valved conduit is recommended (ESC 2024 Class I, Level B).^[1]
• An open distal anastomosis is recommended to improve survival and increase false-lumen thrombosis rates, and hemi-arch repair is recommended over more extensive arch replacement when there is no arch intimal tear or significant arch aneurysm (ESC 2024 Class I, Level B).^[1]
• Also creditable: in selected patients, a valve-sparing root repair may be considered when performed by experienced surgeons (ESC 2024 Class IIb, Level B).^[1]
• Also creditable: with a secondary intimal tear in the arch or proximal descending thoracic aorta, an extended aortic repair with stenting of the proximal descending thoracic aorta (e.g. by the frozen elephant trunk technique) may be considered to reduce late distal aortic complications (ESC 2024 Class IIb, Level C).^[1]

Branch E — Type B

Examiner: It is type B. When do you intervene?

Strong answer:

• ESC 2024 recommends medical therapy including pain relief and BP control in all patients with acute type B (Class I, Level B).^[1]
• In complicated acute type B, emergency intervention is recommended, with thoracic endovascular aortic repair (TEVAR) as first-line therapy except in known or suspected heritable thoracic aortic disease (HTAD) (each Class I, Level B).^[1]
• Complicating features in ESC 2024 Figure 33 are contained or free rupture, organ malperfusion, extension of the dissection or progressive aortic enlargement on serial imaging in the acute phase during the hospital stay, refractory hypertension (ongoing hypertension despite more than three classes of antihypertensive drugs) and refractory pain over 12 h.^[1]
• In uncomplicated acute type B, TEVAR in the subacute phase (between 14 and 90 days) should be considered in selected patients with high-risk features to prevent aortic complications (ESC 2024 Class IIa, Level B); ACC/AHA 2022 says endovascular management may be considered with high-risk anatomic features (COR 2b, LOE B-R).^[1][2]

Follow-up: What do the randomised trials of TEVAR in uncomplicated type B dissection show?^[1][3]

• In the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial, one hundred forty patients in stable clinical condition at least 2 weeks after type B dissection were randomised to stent-graft plus optimal medical therapy or optimal medical therapy alone; 2-year survival was 95.6% with medical therapy versus 88.9% with TEVAR (P=0.15), and the trial turned out to be underpowered.^[3]
• In its retrospective 5-year analysis (INSTEAD-XL, Investigation of Stent Grafts in Aortic Dissection with extended length of follow-up), aorta-specific mortality was 6.9% with TEVAR versus 19.3% without (P=0.04) and progression 27.0% versus 46.1% (P=0.04), while all-cause mortality was 11.1% versus 19.3% (P=0.13).^[4][1]
• ADSORB (Acute Dissection Stentgraft OR Best Medical Treatment) randomised 61 patients with uncomplicated acute type B dissection (history less than 14 days) to best medical treatment with or without a stent graft; for the combined 1-year end point of incomplete or no false-lumen thrombosis, aortic dilatation or rupture, the stent-graft arm was significantly different from best medical treatment alone (P below 0.001), and incomplete false-lumen thrombosis occurred in 43% with the stent graft versus 97% with best medical treatment alone (P below 0.001).^[5][1]

Branch F — After discharge

Examiner: How do you follow the patient up, and what about the family?

Strong answer:

• After TEVAR for AAS, ESC 2024 recommends imaging at 1, 6 and 12 months post-operatively, then yearly until the fifth post-operative year if no abnormalities are documented (Class I, Level B), abnormalities including pseudo-aneurysm, graft infection, endoleak (any type), enlargement of the excluded aneurysm, and stent graft migration, separation or fracture; if no complications occur within the first 5 years, CCT every 2 years thereafter should be considered (Class IIa, Level B).^[1]
• After open surgery for AAS, ESC 2024 says follow-up imaging by CCT and TTE within 6 months, then CCT at 12 months and yearly if findings are stable (in extent of residual false lumen and aortic diameters at any level), should be considered (Class IIa, Level B).^[1]
• In medically treated type B AAS or IMH, ESC 2024 recommends imaging at 1, 3, 6 and 12 months after onset, then yearly if stable (Class I, Level C).^[1]
• ACC/AHA 2022 recommends long-term beta-blockers (unless contraindicated) to control heart rate and BP and reduce late aortic adverse events, adding other antihypertensives (particularly angiotensin receptor blockers and angiotensin-converting enzyme inhibitors) as necessary (COR 1, LOE B-NR).^[2]
• After thoracic aortic dissection, ESC 2024 recommends gathering family history information for at least three generations about thoracic aortic disease, unexplained sudden deaths, and peripheral and intracranial aneurysms (Class I, Level B), and genetic counselling at an expert centre with subsequent testing, if indicated, when there are risk factors for HTAD (Class I, Level B).^[1]