Insights from the assessment of anatomic valve orifice area after transcatheter aortic valve implantation using transesophageal echocardiography

Abstract Background Although transthoracic echocardiography (TTE) is the gold standard for evaluating effective valve orifice area (EOA) after transcatheter aortic valve implantation (TAVI), the continuous formula is inherently different from anatomic valve orifice area because it implies a minimum jet width through the aortic valve. It has also been reported that the doppler method with TTE overestimates the mean gradient due to pressure recovery and is even less accurate after TAVI. On the other hand, recent technological developments have improved image resolution, making valve morphology possible using transesophageal echocardiography (TEE). Purpose The purpose of this study was to compare transcatheter aortic valve (TAV) area using TEE and TTE to evaluate whether there is a significant difference in each area and to explore factors that influence the difference in area. Methods Patients who underwent TEE-guided TAVI and SAPIEN3 implantation between February 2019 and March 2023 and had aortic valve evaluation with TTE before discharge were included. We retrospectively evaluated the TAV after TAVI using TTE and TEE. Aortic valve orifice area was calculated by two methods: EOA index (doppler-area: DA) calculated by the continuous doppler formula using TTE and t-AVA index (trace-area: TA) derived by the trace method using TEE. TAV tracing was performed in early systole on the short-axis image of the aortic valve. The TAV tracing was performed by physicians specializing in echocardiography, and multiple physicians were blinded to the same case to eliminate inter-rater error. The percentage change between the two groups was calculated from the difference in area by TTE and TEE, and the 75th percentile of the percentage change was defined as the cutoff value for the group with the large difference in TAV area. Results Patients whose TAV was difficult to observe by TEE were excluded, and 464 patients were finally analyzed. TA was significantly larger than DA (1.56±0.28 cm2/m2 vs 1.18±0.26 cm2, p<0.001) and similar for all TAV sizes. However, even though TA expanded as valve size increased, the largest area of DA was observed in the 26mm TAV, and the 29mm TAV was comparable to the 26mm TAV. Only a weak correlation was shown between DA and TA (correlation coefficient: 0.356). There were 43 cases of moderate prosthetic valve-patient mismatch (PPM: EOA-i<0.85cm) in DA, but only 1 case in TA. In multivariate logistic regression analysis, women (OR 2.25, 95% CI 1.17-4.34, p < 0.015) and LV mass index (OR 1.01, 95% CI 1.00-1.02, p < 0.041) were independent factors for the large difference in TAV area. Conclusion After TAVI, the TAV area with TEE was larger than the EOA-i with TTE, and PPM was rarely seen. Depending on valve size, patient background, and cardiac morphology, there are cases of overestimation of postoperative AS in TTE, which may need to be carefully evaluated in women and patients with larger LV mass index.