False lumen communications predict aortic remodelling in acute type I dissection repair: measure twice, cut once

Acute DeBakey type I aortic dissection is a dreadful disease necessitating prompt and often times challenging open aortic repair. Despite immediate diagnosis and referral to specialized aortic centres, the postoperative mortality rate may approach 26%, or even rise up to 40% in cases involving end-organ malperfusion [1].

Surgery for DeBakey type I aortic dissection generally comprises resection of the entry tear, replacing the dissected proximal aortic segments, usually by performing an open distal anastomosis with adequate cerebral protection measures. The frozen elephant trunk procedure, which also addresses distal aortic re-entries and facilitates positive aortic remodelling, has been suggested for total arch replacement [2, 3]. However, such a demanding procedure requires a dedicated aortic team and experienced surgeons to ensure optimal outcomes [4]. Alternatively, the hemiarch procedure has been suggested for DeBakey type I aortic dissection if complex arch reconstruction, e.g. a frozen elephant trunk procedure, seems contraindicated or not possible. However, limited proximal repair potentially leaves the downstream aorta (arch and descending aorta) with an increased risk of continued false lumen (FL) perfusion due to distal anastomotic new entry with negative aortic remodelling, leading to the progress of aortic disease and the need for surgery over time [5].

The Ascyrus Medical Dissection Stent (AMDS) has recently emerged as an alternative for hemiarch repair in patients suffering from acute DeBakey type I aortic dissection, obviating the need for total arch repair. This new approach offers shorter cardiopulmonary bypass times and potentially lowers in-hospital mortality, prevents distal anastomotic new entry and facilitates positive aortic remodelling—as evidenced by the dissected aorta repair through stent (DARTS) trial and other studies [2, 6].

In this issue of EJCTS, El-Andari et al. [7] performed a sub-analysis of the DARTS trial to investigate the impact of FL communications on postoperative outcomes after AMDS deployment. They retrospectively analysed the available CT scans of all DARTS participants, which were categorized with regard to the number of FL communications within aortic branches at the supra-aortic or visceral levels. Among the 75 patients in the original DARTS trial, long-term follow-up imaging was available for 28 patients. Their findings indicated that FL communications significantly contributed to aortic diameter growth in the respective Ishimaru zones 3, 6 and 9. However, supra-aortic FL communications only influenced negative aortic remodelling in zone 3 [7].

This DARTS subgroup analysis clearly shows the importance of precise preoperative planning, guided by preoperative high-quality, ECG-gated CT imaging, to identify the right patients, and thereby, achieve optimal long-term outcomes after AMDS therapy.

Since the clinical introduction of the AMDS device, surgeons were strongly advised not to use the uncovered stent in cases with re-entries in the downsteam aorta. As we have recently shown in our own clinical series of 57 patients, there are several unfavourable anatomic features, such as gothic arches and severe descending kinking, which may contribute to a suboptimal result after AMDS deployment [8]. As shown by El-Andari et al. [7], FL communications within the major aortic branches, albeit difficult to diagnose on preoperative, non-ECG-gated CT imaging, may also lead to suboptimal results after AMDS therapy, e.g. negative aortic remodelling.

Regarding those new findings by the DARTS investigators, we believe that supra-aortic FL communications should be recognized as potential contraindications for AMDS therapy. In those cases, total arch replacement by frozen elephant trunk should be favoured, while patients undergoing hemiarch repair instead may be reoperated on the arch at lower risk during follow-up. In the presence of visceral FL communications, AMDS therapy still allows for proximal aortic remodelling and ceasing of impending end-organ, especially cerebral, malperfusion. However, close surveillance—as recommended by the current EACTS/STS guidelines [4]—is mandatory to allow for timely planning of (thoracic) endovascular aortic repair of the downstream aorta during follow-up.

In summary, the AMDS has been shown to be a valuable treatment option for acute DeBakey type I aortic dissection, potentially shortening operation times with acceptable mortality rates in the DARTS trial as well as in real-world scenarios [5, 6, 8]. Despite these beneficial effects, the AMDS device should not be used liberally in patients with an unfavourable anatomy, such as gothic arch, severe aortic kinking, or aortic re-entries (FL communications) in the arch and its branches as well as in the descending aorta. Therefore, repetitive preoperative screening of available CT imaging by treating clinicians and surgeons is strongly recommended—especially to detect supra-aortic FL communications—to achieve an optimal result after AMDS therapy.

Conflict of interest: none declared.

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