Looking for a definition of aortic dilatation in overweight and obese individuals: body surface area-indexed values versus height-indexed diameters.

Introduction: Patient's body size is a significant determinant of aortic dimensions. Overweight and obesity underestimate aortic dilatation when indexing diameters by body surface area (BSA). We compared the indexation of aortic dimensions by height and BSA in subjects with and without overweight to determine the upper normal limit (UNL).

Methods: The MATEAR study was a prospective, observational, and multicenter study (53 echocardiography laboratories in Argentina). We included 879 healthy adult individuals (mean age: 39.7 ± 11.4 years, 399 men) without hypertension, bicuspid aortic valve, aortic aneurysm, or genetic aortopathies. Echocardiograms were acquired and proximal aorta measured at the sinus of Valsalva (SV), sinotubular junction (STJ), and ascending aorta (AA) levels (EACVI/ASE guidelines). We compared absolute and indexed aortic diameters by height and BSA between groups (men with body mass index [BMI] < 25 and BMI ≥ 25, women with BMI < 25 and BMI ≥ 25).

Results: Indexing of aortic diameters by BSA showed significantly lower values in overweight and obese subjects compared to normal weight in their respective gender (for women: SV 1.75 cm/m² in BMI < 25 vs. 1.52 cm/m² in BMI between 25 and 29.9 vs. 1.41 cm/m² in BMI ≥ 30; at the STJ: 1.53 cm/m² vs^. 1.37 cm/m² vs. 1.25 cm/m²; and at the AA: 1.63 cm/m² vs. 1.50 cm/m² vs. 1.37 cm/m²; all p < 0.0001 and for men, all p < 0.0001). These differences disappeared when indexing by height in both gender groups (all p = NS).

Conclusion: While indexing aortic diameters by BSA in obese and overweight subjects underestimate aortic dilation, the use of aortic height index (AHI) yields a similar UNL for individuals with normal weight, overweight, and obesity. Therefore, AHI could be used regardless of their weight.