Increased Overweight among Patients with Acute Aortic Type A Dissection: The Different Aspects of a Single Risk Factor. Evidence from an Aortic Dissection Registry

Aortic size index (ASI) i.e. aortic diameter/body surface area (BSA) was tested to define dilated ascending aorta and the prophylactic replacement timing. Overweight has a remarkable impact on BSA calculation and paradoxically lowers ASI score and the risk of dissection. Moreover, most of acute aortic type A dissections (AADA) are observed in dilated aortas below surgical indication.

Characteristic of patients presenting with AADA were analyzed, Body Mass Index (BMI), BSA and ASI were calculated. A second normalized ASI (ASI-2) was also computed using a normal BMI identified as the mean BMI (23 kg/m2) of our patients with normal body weight. CT scan measurements of aortic diameters were performed including false lumen or hematoma.

Between 01/2002 and 12/2017 132 patients were operated for AADA at our institution, 109/132 were considered for this study. All but 3 patients had a dilated ascending aorta, the mean diameter was 51±7.4 mm, 75% of dissections occurred at diameters 55 mm in 8 cases. Using the normalized ASI-2 (i.e. removing the bias due to overweight), 18/56 (32%) of overweight/obese low risk patients shifted to the moderate risk class (i.e. from no indication to indication for prophylactic surgery).

In our study the proportion of overweight/obese patients with AADA was significantly higher than the proportion of overweight/obese patients matched for age in the general population of our region (Pearson c², p<0.001). Beside genetic or congenital conditions, an improved surveillance taking into account overweight is mandatory for prophylactic aortic surgery. The recently published aortic diameter/height index (AHI) must be considered.