Clinical practice on opposite sides of the Atlantic has long revealed striking disagreements in the management of the same disease entities. Structural and conceptual differences in healthcare systems, along with divergent interpretations of available evidence and regulatory requirements for biomedical devices and therapies, often lead to contrasting clinical perspectives.

This divergence is evident in the latest guidelines. Both the 2022 AHA–ACC and STS documents assign a class IIb recommendation to thoracic endovascular aortic repair (TEVAR) for uncomplicated forms, restricted to highly selected cases and without well-defined selection criteria. Conversely, the 2024 European EACTS–STS guidelines support a class IIa recommendation for TEVAR in uncomplicated cases, whether or not risk factors are present.

Before delving into this central controversy, the review provides an opportunity to analyze the distinctive conceptual stance adopted by the authors and the broader North American school regarding the classification and management of acute type B aortic dissection.

The classification proposed in the review stands out for not adopting the TEM system, which is widely accepted due to its descriptive capacity and applicability to diverse clinical scenarios. Instead, the authors favor the SVS–STS classification scheme, which merges the DeBakey system with the Ishimaru endograft zoning approach. Although Ishimaru’s classification was created as a standardized map to guide endovascular access and device deployment, in this context it is repurposed to define dissection extent.

Thus, dissections involving zones 0 or 1 are designated type A, whereas those confined to zone 2 and beyond without zone 0 or 1 involvement are considered type B. In both systems, the proximal location of the primary entry tear determines the classification. Although this correlates with the most frequent clinical presentations, such a framework does not account for variants such as non-A non-B dissections or retrograde propagation. Crucial clinical elements such as radiologic or symptomatic malperfusion are also not included in the classification scheme.

Initial medical therapy consisting of analgesia followed by beta-blockers and antihypertensive agents receives a class I recommendation in all major guidelines. In this regard, the document presents a treatment algorithm that again reflects a distinctly conservative posture. TEVAR is recommended exclusively for acute complicated forms, whereas subacute and chronic phases are reserved for surgical or endovascular repair when meeting traditional criteria such as aortic diameter >55 mm, growth >5 mm over 6 months, or acute complications such as rupture or malperfusion.

The rationale for earlier intervention during the subacute phase represents a major area of discussion through the rest of the review. Subacute treatment may offer the optimal balance: the aorta has begun the remodeling process, reducing the risk of procedural rupture, yet degeneration has not progressed to the point of precluding access or sealing due to aneurysmal morphology. By contrast, delaying treatment to the chronic phase risks losing the endovascular window and shifts the strategy toward open repair, along with the cumulative burden of adverse aortic events when remodeling proceeds uninterrupted.

A further timing question relates to whether to apply a systematic interventional strategy to all patients in the acute or subacute phase or restrict treatment to those exhibiting predictors of unfavorable evolution. Much of the available evidence comes from two randomized studies, ADSORB and INSTEAD, together with the extended INSTEAD-XL follow-up. These enrolled relatively small cohorts, 31 and 140 patients respectively, undergoing entry-tear coverage with endografts during the subacute phase of uncomplicated type B dissections. Endovascular repair consistently demonstrated superior aortic remodeling, although a survival benefit emerged only in INSTEAD-XL after extending follow-up to 5 years.

Although numerous predictors of adverse evolution in subacute uncomplicated type B dissection have been proposed (maximum aortic diameter ≥40 mm, false lumen >22 mm, entry tear >1 cm, tear located on the lesser curvature, or interval growth >5 mm since diagnosis), most originate from observational series rather than from randomized evidence such as ADSORB or INSTEAD. In day-to-day clinical practice, however, one or more of these criteria are frequently present, which could support a more systematic interventional strategy. Even so, this remains a personal interpretation. The reviewer favors using these features to justify early TEVAR while acknowledging that certain specific cases may still be appropriately managed with medical therapy alone if they appear to harbor a favorable prognosis.

Regarding the technical approach, the proposed treatment paradigm centers on sealing the primary entry tear with an endograft positioned in zone 3. When extension into zone 2 is required, TEVAR combined with carotid–subclavian bypass remains a widely applied option. An emerging alternative involves a lateral-branch thoracic stent graft such as the Gore TAG system, designed to maintain perfusion of the left subclavian artery while achieving a precise seal at the level of the left carotid artery.

The authors discourage older strategies such as PETTICOAT, which extended the covered stent distally using a bare-metal stent to promote remodeling and mitigate dynamic malperfusion (present in approximately 80% of cases). In theory, this approach could have optimized remodeling while minimizing spinal cord ischemia risk since the bare stent avoids extensive coverage of segmental arteries. It also offered a simplified alternative to fenestrated or branched endovascular repair in the setting of malperfusion. However, STABLE I and II, together with STABILISE, reported inconsistent remodeling outcomes and device-related complications, ultimately curtailing enthusiasm for these techniques.

COMMENTARY:

Overall, this review reflects a viewpoint on type B aortic dissection management that feels reminiscent of an earlier era of training and therapeutic conservatism. Despite the more restrictive regulatory environment imposed by CE marking compared with FDA approval, the broader availability of a full device portfolio in Europe has fostered a more proactive mindset toward the underlying pathophysiology of aortic remodeling. This has led to earlier acceptance of still-developing evidence supporting subacute-phase intervention (48 hours to 14 days) for type B dissection. On the European side of the Atlantic, there is greater willingness to invest in modifying the disease course before irreversible aneurysmal changes occur. By contrast, American management remains more firmly tied to chronic-phase thresholds driven by maximal diameter criteria, with the clinical and prognostic consequences that such delay entails.

REFERENCE:

Mussa FF, Kougias P. Management of Acute Type B Aortic Dissection. N Engl J Med. 2025;393:895-905.