Strategies for Aortic Root Measurement in Patients Undergoing Surveillance for Thoracic Aortic Disease

Objectives: Several measurement techniques have been proposed to address the non-circular geometry of the aortic root. The Laplace diameter metric incorporates the cloverleaf anatomy of the aortic root and is derived via measurement of sinus-to-commissure lengths with subsequent doubling of the largest radius from the center. This study compares the conventional sinus-to-sinus with the novel Laplace method for sizing the aortic root and quantifying its implication on surgical decision-making. Methods: Patients undergoing surveillance at a high-volume aortic center were categorized by aortic root morphology as nondilated, non-syndromic dilated, bicuspid aortic valve and Marfan syndrome. Aortic root diameters by sinus-to-sinus and Laplace diameter methods were measured on computed tomography, compared using paired t-tests, and correlated using Spearman rank coefficients. Results: Of the 1297 patients assessed, 530 were included in the final analysis (nondilated n = 113, non-syndromic dilated n = 347, bicuspid aortic valve n = 50, Marfan syndrome n = 17). Aortic root diameters were significantly larger by Laplace than sinus-to-sinus diameter across all groups (sinus-to-sinus: 1.9 ± 5.5 mm; Laplace: 44.9 ± 7.0 mm; 95% confidence interval 2.72-3.34; p < 0.0001). Although Laplace and sinus-to-sinus diameter were correlated (Spearman r = 0.6789, 95% CI 0.6-0.7; p < 0.0001), the relationship was non-linear (R² = 0.492). Laplace diameter increased the proportion of patients meeting surgical thresholds (2022 AHA/ACC guidelines) versus sinus-to-sinus: nondilated 0% vs. 1.77%, non-syndromic dilated 4.9% vs. 25.1%, bicuspid aortic valve 10.0% vs. 26.0%, and Marfan syndrome 23.5% vs. 52.9%. Conclusions: On average, Laplace diameter exceeded sinus-to-sinus diameter by 3 mm and would extend surgical eligibility to an additional 21% of patients under current guidelines.