Surgery for type I aortic dissection, often performed in an emergency setting, remains a complex procedure associated with substantial mortality, although outcomes are increasingly encouraging in experienced centres.

Traditionally, the primary goal has been to achieve satisfactory results during the acute phase of the procedure, namely reducing intraoperative and perioperative mortality.

Within the surgical community, there is still debate as to whether a more conservative, technically simpler and more reproducible approach, such as hemiarch replacement, should be preferred over a more aggressive and technically demanding operation, such as total arch replacement with or without an elephant trunk. The available evidence comparing hemiarch replacement with total arch replacement has yielded heterogeneous results, leaving uncertainty as to whether more extensive surgery translates into improved long-term survival.

The surgical societies, EACTS and STS, have made a major effort in their latest clinical practice guidelines on aortic disease to simplify decision-making in a complex setting and in a condition that is markedly heterogeneous and highly patient-specific.

As surgical mortality has improved, many patients now survive the acute phase of dissection and subsequently enter the natural history of residual aortic disease. Adverse remodelling of the residual dissected aorta is well known and is associated with unfavourable aortic events, including aneurysmal degeneration, aortic rupture and the need for further aortic reintervention.

With the advent and growing adoption of the frozen elephant trunk (FET) technique, favourable remodelling of the residual false lumen has been observed, suggesting potential mid- and long-term benefits.

This study sought to compare aortic remodelling outcomes across different surgical strategies, with particular emphasis on techniques involving an elephant trunk. In cardiac surgery, as in life, sometimes less is more. On other occasions, the best may become the enemy of the good. And sometimes, the more sugar, the sweeter. Finding the right extent of surgical repair for each patient is a true art, and it is even more challenging in life-threatening scenarios such as type I aortic dissection.

To address this question, the authors analysed a single-centre retrospective study from Seoul, Korea, including patients who underwent surgery for type I aortic dissection between January 2004 and June 2022. A total of 327 patients were included. Patients were divided into 4 groups according to the surgical technique used: no total arch replacement, conventional total arch replacement without an elephant trunk, total arch replacement with a classic elephant trunk (CET) and total arch replacement with a frozen elephant trunk (FET). The primary outcome was positive remodelling of the residual false lumen and secondary aortic events.

False lumen remodelling was assessed by CT, with measurements taken in the descending thoracic aorta at the level of the main pulmonary trunk and at the level of the ninth thoracic vertebra. False lumen thrombosis was defined as absence of contrast enhancement within the false lumen in both the arterial phase and the 3-minute delayed phase. False lumen regression was defined as disappearance of the false lumen on subsequent CT scans or complete false lumen thrombosis with a residual false lumen thickness of less than 5 mm. CT angiography was performed during the first postoperative week, at 6 and 12 months, and annually thereafter. Secondary outcomes included early postoperative results: 30-day mortality, in-hospital mortality, intubation time, length of hospital stay and early complications.

In this cohort of 327 patients with type I dissection, the groups were broadly comparable, except for greater instability, defined by CPR/ECMO, and more proximal entry tears in the non-total arch replacement group. In contrast, the conventional total arch replacement plus CET and FET groups had more frequent malperfusion and more extensive distal involvement, with descending aortic entry tears present in up to 58% of patients in the FET group. Total arch replacement was associated with longer circulatory arrest time, at 65 minutes, approximately 20 minutes longer than in the non-total arch replacement group, with no differences between the CET and FET groups. There were no relevant differences in major complications or early mortality, although vocal cord palsy was more frequent in the conventional total arch replacement and CET groups (p < .001), with no cases of spinal cord ischaemia.

During follow-up, at 46 months, the elephant trunk group (CET/FET) was associated with greater false lumen thrombosis and regression in both the proximal and distal descending aorta. FET achieved earlier thrombosis, with 75% at 8 months versus 14 months with CET, but without differences in the final outcome after statistical adjustment. Proximal aortic events were less frequent with CET and FET than with strategies without an elephant trunk (p = .010), with no differences in distal aortic events or overall survival.

Overall, the key benefit was improved aortic remodelling with ET, with CET and FET showing equivalent mid-term results.

COMMENTARY:

This study provides 2 main findings. First, the elephant trunk (ET) technique, whether performed with CET or FET, is associated with significantly more favourable aortic remodelling than conventional surgery. Second, and particularly relevant, the classic elephant trunk (CET) achieves remodelling outcomes comparable to those of the frozen elephant trunk (FET), even though FET promotes faster and more consistent false lumen thrombosis, favouring earlier aortic stabilization. This effect is probably explained by the fact that both techniques eliminate the main entry tears and reduce distal new entries, thereby facilitating false lumen thrombosis.

However, FET has important drawbacks, including the risk of spinal cord ischaemia, up to 6.5%, particularly in patients with intercostal arteries dependent on the false lumen, as well as complications such as distal stent graft-induced new entry (SINE), reported in approximately 12.7%.

Conversely, although the classic elephant trunk may raise concerns regarding less effective true lumen expansion, this study supports its mid-term efficacy. Overall, any elephant trunk procedure appears to reduce the need for reintervention, although reintervention remains frequent, and open surgery continues to be the most definitive option. In this context, CET emerges as a valid alternative to FET, particularly in patients with high neurological risk, complex anatomy or limited resources.

It therefore seems clear that, in such a complex and polymorphic disease, success depends on tailoring the strategy to the clinical presentation, patient risk, available resources and experience of the surgical team. Whenever possible, in young patients, in those with suspected genetic aortopathy and in patients with clinical signs of malperfusion, undertreating the distal aorta may influence mid- and long-term prognosis.

REFERENCE:

Park YK, Chang HW, Park KH, Jung JC, Lee JH, Kim JS. Impact of the Elephant Trunk on Distal Remodelling After Surgery for Acute Type I Aortic Dissection. Interdiscip Cardiovasc Thorac Surg. 2026 Feb 5;41(2):ivag023. doi: 10.1093/icvts/ivag023.