Type A aortic dissection in aneurysms having modelled pre-dissection maximum diameter below 45 mm: should we implement current guidelines to improve the survival benefit of prophylactic surgery?

Abstract

Objectives: Current guidelines recommend prophylactic replacement of the ascending aorta at an aneurysmal diameter of >55 mm to prevent acute Type A aortic dissection (TAAD) in non-Marfan patients. Several publications have challenged this threshold, suggesting that surgery should be performed in smaller aneurysms to prevent this devastating disease. We reviewed our experience with measuring aortic size at the time of TAAD to validate the existing recommendation for prophylactic ascending aorta replacement.

Methods: All patients who had been admitted for TAAD to our emergency department from 2014 to 2019 and underwent ascending aorta replacement were included. Marfan patients were excluded. The maximum diameter of the dissected aorta was measured preoperatively using CT scan. We estimated the aortic diameter at the time of dissection to be 7 mm smaller than the measured maximum diameter of the dissected aorta (modelled pre-dissection diameter).

Results: Overall, 102 patients were included. Of these, 67 were male (65.6%) and 35 were female (34.4%), and the cohort's mean age was 65 ± 12.1 years. In addition, 66% were treated for arterial hypertension. The mean maximum modelled pre-dissection diameter was 39.6 ± 4.8 mm: 39.1 ± 5.1 mm in men and 40.7 ± 2.8 mm in women (P = 0.1). The cumulative 30-day mortality rate was 19.6% (20/102).

Conclusions: TAAD occurred at a modelled aortic diameter below 45 mm in 87.7% of our patients. Therefore, the current aortic diameter threshold of 55 mm excludes ∼99% of patients with TAAD from prophylactic replacement of the ascending aorta. The maximum diameter of the ascending aorta warrants reappraisal and this parameter should be a distinct part of a personalized decision-making process that also takes into account age, gender and body surface area to establish the surgical indication for preventive aorta replacement aimed to improve the survival benefit of this procedure.

Keywords: Acute aortic syndrome; Aortic aneurysm; Aortic dissection; Aortic surgery.

Figure 1:

Centre line reconstructions of preoperative CT scan with contrast medium. (A) Patient 4: the maximum diameter of the dissected aorta was measured including true and false lumens, outer to outer aortic wall diameter, on axial transverse images perpendicular to the central line. (B) Patient 37: measure of the length of the ascending aorta. The ascending aorta begins at the plane corresponding to the sinotubular junction (white line 1) and extends to the plane immediately proximal to the origin of the brachiocephalic artery (red line 2): 88.5 mm corresponds to the length of the dissected ascending aorta.

Figure 2:

Distribution of pre-dissected maximum ascending aorta diameters, according to size and gender. The pre-dissected (modelled) diameter was obtained by measuring the maximum aortic diameter of the dissected ascending aorta of −7 mm, according to Mansour et al. results [9]. Grey columns correspond to female gender. TAAD: Type A aortic dissection.

Figure 3:

Scatter plot of dissected ascending aorta length. Aortic length was measured on centre line reconstructions starting from the plane corresponding to the sinotubular junction to the plane immediately proximal to the origin of the brachiocephalic artery. One hundred twenty millimetres is the cut-off value for calculating the Tübingen Aortic Pathoanatomy score [11].