Accuracy of TTE in Aortic Annulus Sizing: Comparison with Intraoperative Measurements

Abstract

Objectives: This study aims to evaluate the accuracy of transthoracic echocardiography (TTE) in measuring the aortic annulus size compared to actual intraoperative measurements at the National Institute of Cardiovascular Diseases (NICVD), Karachi. Methodology: This retrospective cross-sectional study was conducted from January 2021 to December 2022 in the adult cardiac surgery department of NICVD, Karachi, Pakistan. Preoperative aortic annulus measurements obtained via echocardiography were compared with intraoperative valve sizing. Frequencies and percentages were calculated for each degree of size difference. Agreement between the measurements was assessed using a Bland–Altman plot, with a 95% limits of agreement interval. Results: A total of 104 patients were included, with 71 (68.3%) males and a mean age of 47 ± 15 years. The mean aortic annulus diameter measured by preoperative echocardiography was 23.2 ± 2.5 mm, while the mean intraoperative valve size was 22.5 ± 1.8 mm. Preoperative echocardiography matched the intraoperative valve size in 21.2% (22) of patients, underestimated by at least one size in 52.9% (55), and overestimated by at least one size in 26% (27). The Bland–Altman analysis revealed poor agreement between the two methods, with limits of agreement ranging from -4.41 to 2.99 mm. No statistically significant association was found between the measurement differences and patient-related factors such as gender, age, or presence of aortic regurgitation (AR) or aortic stenosis (AS). Conclusion: Accurate preoperative measurement of the aortic annulus is critical to avoid last-minute conversion to more complex surgical procedures during aortic valve replacement (AVR). Although imaging technologies have advanced considerably, integrating multiple modalities provides the most comprehensive assessment of aortic root anatomy. Because TTE offers only a two-dimensional sagittal view, it frequently overestimates the annulus diameter. Therefore, three-dimensional TEE and multidetector computed tomography (MDCT) should be considered gold standards, as they provide isotropic three-dimensional images that allow more objective and reproducible quantitative assessments.