Application of "Fabulous" stent system to improve aortic remodeling after TEVAR for type B aortic dissection

It is known that the Proximal Extension To Induce Complete Attachment (PETTICOAT) technique improves the distal aortic remodeling compared with standard thoracic endovascular aortic repair (TEVAR). ^[1,2] However, the only available Zenith Dissection Endovascular System (Cook Medical Inc., Bloomington, Ind, USA) has several limitations, including only two sizes (36 mm and 46 mm) and an one-taper design, which may not be suitable for the complex morphology of dissection at distal aorta, particular for the east Asian population. Thus, our center designed the new "Fabulous" stent system and acheieved better early curative effect.

Our center designed "Fabulous" stent system based on the conception of PETTICOAT technique. It included the proximal covered stent graft and the distal bare stent component, which were designed to include 13 models to adapt various anatomical characteristics (the diameter of stent graft and bare stent ranged between 20–44 mm and 16–40 mm, respectively). The deployment of proximal stent graft was similar to the standard TEVAR; the distal bare stent was placed above the level of the celiac artery orifice with 3–4 cm overlapping with the proximal stent graft. To further assess whether the "Fabulous" stent system was associated with better aortic remodeling versus standard TEVAR alone, we conducted a comparative study between the group with "Fabulous" stent system and with standard stent grafts at 1-year follow-up.

The study was approved by the relevant ethics committee (unique protocol ID: WQ1601). All patients enrolled provided written informed consent. The "Fabulous" stent system group was a prospective single-arm study conducted at multicenter between December 2017 and October 2019 comprised of 134 type B aortic dissection (TBAD) patients, ^[3] and 159 TBAD patients receiving standard TEVAR from multicenter during the same period were included in control group. Two groups have the consistent inclusion and exclusion criteria, and Inverse Probability Treatment Weighting (IPTW) was used to balance baseline characteristics and analyze the outcomes [Supplementary Table 1, https://links.lww.com/CM9/B504].

There was no significant difference in the rate of endoleak between the two groups, but all patients in "Fabulous" group have no reintervention and stent graft-induced new entry (SINE). The possible reason might be that the high and low wave with semi-suturing and flexibility design ensured that the bare stent component had good plasticity and adapted well to the aorta, reducing the risk of SINE. To assess aortic remolding, the distal aorta was divided into two segments: (segment 1) the thoracic aorta from distal end of the stent graft to the celiac trunk which contained the bare stent; (segment 2) from the celiac trunk to the lower renal artery. Patients in "Fabulous" group had better outcomes of true lumen (TL) expansion and false lumen (FL) diminution than those in the standard TEVAR group in the segment 1 (22.95 ± 5.55 mm vs. 18.99 ± 6.12 mm, P = 0.001, minimum diameter of TL; 9.06 ± 12.27 mm vs. 25.20 ± 12.65 mm, P <0.001, maximum diameter of FL). As for the outcomes of the segment 2, "Fabulous" group further demonstrated better outcomes of TL expansion and FL diminution than standard TEVAR therapy (16.97 ± 5.01 mm vs. 15.23 ± 4.76 mm, P = 0.025, TL diameter; 11.53 ± 8.87 mm vs. 18.14 ± 10.10 mm, P <0.001, FL diameter).

To better showed the changes of distal aortic remodeling of pre-operation and 1-year follow-up between the two groups, line graphs were made to compare the differences. In the segment 1, "Fabulous" group had better trend of TL expansion and FL regression than the standard TEVAR group (8.98 ± 0.91 mm ["Fabulous" group] vs. 5.84 ± 0.79 mm [standard TEVAR group], P <0.001, change of minimum diameter of TL; –20.9 ± 1.67 mm ["Fabulous" group] vs. –4.96 ± 1.46 mm [standard TEVAR group], P <0.001, change of maximum diameter of FL), and "Fabulous" group decreased the total aortic lumen area (7.36 ± 3.17 mm ² [1-year follow-up] vs. 8.58 ± 2.62 mm ² [pre-operation], P <0.001, total aortic lumen area). As for the outcomes in the segment 2, "Fabulous" group still showed better trend of TL diameter expansion than standard TEVAR group (2.71 ± 0.42 mm ["Fabulous" group] vs. 2.54 ± 0.4 mm [standard TEVAR group], P <0.001) and no obvious trend of total aortic lumen area expansion (6.32 ± 2.47 mm ² [1-year follow-up] vs. 6.21 ± 1.66 mm ² [pre-operation], P = 0.510, total aortic lumen area) [Figure 1A, B]. In the aspect of FL thrombosis, patients in "Fabulous" group had better trend of FL thrombosis than those in standard TEVAR group at segment 1 [Figure 1C].

Figure 1: The comparison of aortic remodeling between "Fabulous" and standard TEVAR. Line graph of aortic diameter changes at the segment 1(A) and segment 2(B) between the standard TEVAR and "Fabulous" groups. (C) The change rate of FL thrombosis at segment 1. FL: False lumen; TEVAR: Thoracic endovascular aortic repair; TL: Ture lumen.

Compared with Zenith Dissection Endovascular System, although patients in Study for the Treatment of complicated Type B Aortic Dissection using Endoluminal repair (STABLE) trials benefitted from the PETTICOAT technique in terms of promoting distal FL thrombosis and TL expansion at 1-year follow-up, the diameter of abdominal aorta exhibited significant overall increase both in the SI and II trials. ^[4,5] On the contrary, no obvious distal aortic enlargement was observed in our "Fabulous" group (6.32 ± 2.47 mm ² [1-year follow-up] vs. 6.21 ± 1.66 mm ² [pre-operation], P = 0.510, total aortic lumen area in segment 2). The potential reasons might be listed as follows: Firstly, the supporting section of bare stent was knitted with monofilament nitinol wire to ensure bearing certain radial compression; secondly, the connecting section of bare stent was knitted with multiple nitinol wire to ensure that the stent had good flexibility and conformability; thirdly, the multi-taper design feature with a 15–30% rate of oversizing, which was less than that of the Zenith Dissection Endovascular system, could adapt to the different situations better. The features of bare stent design in "Fabulous" stent system gained better TL remodeling without obvious distal aortic expansion.

In summary, the application of "Fabulous" stent system had better outcomes of distal aortic remodeling than standard TEVAR, while did not increase the incidence of complications. It could adapt to the Asian populations' vascular anatomy better and still needed large and long-term follow-up to test its efficiency.

Funding

This study was supported by grants from the National Science Foundation of China (No.81970412); Shanghai Municipal Science and Technology Commission Innovation Fund (No.22S31904800); Fujian Province Health Science and Technology Fund (No. 2021GGB030); Shanghai Municipal Science and Technology Commission Innovation Fund (No.18441902400); National Clinical Research Center for Interventional Medicine Fund (No.2021-004); Shanghai Municipal Health Commission (No. 20214Y0474); Xiamen Municipal Health Science And Technology Program Fund (No. 3502Z20194034); and Fudan Zhangjiang Clinical Medicine Innovation Fund (No. KP7202115)Foundation:.

Conflicts of interest

None.