Acute Type A Aortic Dissection (ATAAD) represents a medical emergency with high mortality if not surgically addressed within the initial hours. During the hyperacute phase, the aortic tissues enter an inflammatory state, rendering them particularly fragile, which may lead to long-term complications necessitating subsequent interventions. These interventions may be required for various reasons, such as the development or progression of aortic insufficiency, a gradual increase in residual native aortic diameters, false lumen expansion, graft infection, and the formation of aortic pseudoaneurysms (PA).

The incidence of PA following ATAAD repair is estimated at 10-24%, making it a feared and poorly understood complication. Clinical guidelines vary on when and how to address them. For example, the Canadian Cardiovascular Society recommends surgery when PA reaches a maximum diameter of 2 cm, regardless of cause. In contrast, the European Society of Cardiology suggests open surgery without consideration of size or cause, albeit without a specific level of evidence recommendation. Despite this, scant attention has been paid to the natural history of PA, its prognosis, and treatment in uncomplicated or asymptomatic patients following aortic replacement for any reason.

The objective of this article was to examine the safety and efficacy of a conservative approach to PA and compare this approach with standard surgical treatment. They retrospectively examined 39 patients who presented an aortic pseudoaneurysm after ATAAD surgery to evaluate outcomes (baseline characteristics, presentation, and freedom from aortic events and mortality). Initially, 31 patients were identified for conservative treatment (CT). After close follow-up, 5 of them underwent surgery, bringing the total number of surgically treated patients (ST) to 13 for long-term analysis, while 26 remained in the conservative group. The mean follow-up for the entire cohort was 7.9 years. Freedom from aortic-related mortality at 1, 5, and 10 years was 100%, 83.3%, and 72.9% for the ST group and 95.8%, 77.3%, and 77.3% for the CT group (p = 0.35).

In light of these results, the authors conclude that a conservative approach for aortic pseudoaneurysms may be justified in asymptomatic patients with high surgical risk. Close follow-up by specialized clinicians is essential to refer patients for surgery when necessary.

COMMENTARY:

Chaud et al. present in this article the evolution of a series of 39 patients with aortic pseudoaneurysm as a complication following repair of acute Type A aortic dissection. Traditionally, the general belief has been that aortic pseudoaneurysms require surgical intervention. However, the authors challenge this premise by offering a thorough comparison of long-term outcomes between conservative management and surgery in these cases. The most remarkable finding in this study is the objective lack of significant differences in aortic and all-cause mortality at 10 years. This represents a milestone by justifying, for the first time, the feasibility of a conservative approach for a specific population of asymptomatic patients with pseudoaneurysms. Furthermore, this finding highlights the importance of close and rigorous follow-up for these patients.

This article rests on three fundamental pillars that underscore its importance. Firstly, it presents a patient series with PA that exceeds any previous study in size. Secondly, by excluding patients with infections, the study achieves a notable degree of cohort homogeneity regarding pseudoaneurysm etiology. Finally, the study’s groundbreaking contribution lies in its innovative approach to conservatively addressing pseudoaneurysms, marking a milestone in the understanding and treatment of this complication.

Nonetheless, to avoid premature conclusions, it is essential to highlight several aspects related to the size of the pseudoaneurysms in each of the analyzed groups. Patients managed conservatively, comprising two-thirds of the cohort, presented a mean pseudoaneurysm size of 10 mm, whereas the surgical group showed an average size of 18 mm. Notably, those initially opting for conservative management who later required surgical intervention displayed a pseudoaneurysm size of 20 mm at the time of the intervention. It is crucial to consider that the existing literature on pseudoaneurysms after aortic dissection is sparse and often limited to isolated case reports. Consequently, recommendations tend to be ambiguous and contradictory. Certain guidelines and scientific societies, such as the Canadian Cardiovascular Society consensus, suggest intervention for pseudoaneurysms larger than 20 mm, despite limited solid scientific evidence to support this threshold. Chaud et al.’s study, within this context, may bolster the size threshold proposed in the consensus document.

However, if we factor in the variable of time, the study’s results should be interpreted with caution. On the one hand, the time elapsed from the initial aortic dissection repair to the pseudoaneurysm diagnosis in conservatively treated patients is shorter than for those undergoing surgical treatment (1.4 years versus 6.3 years). On the other hand, the follow-up duration after diagnosis in the conservative treatment group was only 5.1 years. This implies that pseudoaneurysms in the conservative group were diagnosed shortly after surgery, and the follow-up period was significantly shorter compared to the mean cohort follow-up duration, which was 8.1 years. In summary, while initial follow-up and observation with conservative treatment may be a suitable strategy, prolonged monitoring is necessary to ensure pseudoaneurysms do not continue to increase in size over time.

Another intriguing aspect is addressing the issue from the perspective of the relationship between PAs and the use of different materials during emergency surgery to treat aortic dissection, particularly the application of Teflon felt or the use of biological surgical adhesives such as BioGlue®. BioGlue®, composed of bovine serum albumin and glutaraldehyde, is used to enhance suture hemostasis and strengthen delicate aortic tissue and was approved by the FDA in 2001 for use in aortic dissection cases. In the study, the authors found no statistically significant differences in the prevalence of Teflon felt use (60% in the conservative group vs. 36.4% in the surgical group) or BioGlue (12% vs. 27% between conservative and surgical management groups, respectively). Teflon felt is widely recognized as a well-established protective agent against pseudoaneurysm formation, while BioGlue®, due to its glutaraldehyde content, has been studied for its potential cytotoxicity and association with pseudoaneurysm formation in prior research. The lack of a statistically significant relationship in this study between BioGlue® use and pseudoaneurysm progression toward a poor prognosis requiring surgery might be attributed to the relatively small cohort size. Although other studies have explored the role of BioGlue®, firm conclusions remain elusive. Should the hypothesis of glutaraldehyde-induced cytotoxicity hold true, BioGlue® could mask leaks under a seemingly successful hemostasis. Ultimately progressing in the absence of an intact aortic wall to contain them as PA. Therefore, it is currently impossible to issue a recommendation on BioGlue® use in ATAAD surgery.

Infections are widely recognized as a significant etiological factor in PA formation. In this study, all patients showing evidence of infection were meticulously excluded to maintain cohort homogeneity, as any infection alone would necessitate surgical intervention.

Endovascular treatment has shown to be an effective option with acceptable outcomes for managing pseudoaneurysms in the descending aorta. However, in the ascending aorta, endovascular options are generally limited to exceptional cases involving small pseudoaneurysms located in zone 0 with suitable landing zones, and they are documented only as rare clinical cases. In the present article, the possibility of endovascular treatment has yet to be considered. It is likely that in the coming years, the development of branched or fenestrated stent grafts will enable the preservation of supra-aortic trunks, thus allowing more widespread endovascular management of this complication. Nevertheless, this perspective remains unexplored within this study.

The study’s findings merit special recognition, firstly because it constitutes the largest series of patients with PA post-aortic dissection surgery; and secondly, due to the outstanding outcomes achieved through both conservative and surgical treatment. One of the most noteworthy takeaways lies in the choice of conservative management, emphasizing the importance of close clinical and radiologic follow-up. This is crucial to detect potential signs of new symptoms, such as angina suggesting left coronary trunk compression, heart failure secondary to fistulas into other cavities, among others. Additionally, rapid PA growth or sizes exceeding 20 mm should be closely monitored, as these indicators could signal the need for surgical intervention. Further study with extended follow-up of these patients will likely clarify lingering questions about this feared complication.

REFERENCE:

Chaud GJ, Mohammadi S, Cervetti MR, Guimaron S, Sebestyen A, et al. E. Aortic Pseudoaneurysm After Type A Aortic Dissection: Results of Conservative Management. Semin Thorac Cardiovasc Surg. 2023 Autumn;35(3):457-464. doi: 10.1053/j.semtcvs.2022.04.004.