Rapid Fire Abstract session: new insights in TAVI

Background: The size of the transcatheter heart valves (THV) is overestimated up to 20% based on aortic annulus diameter measured using computed tomography (CT). However, the prosthesis may not be fully expanded during implantation. THV underexpansion might have detrimental clinical consequences. Purpose The aim of this study was to define the degree of underexpansion degree of different THVs after implantation, introduced as the shrinking index. Methods: In total we enrolled 114 patients (68 men, 79 ± 8 years old) who underwent transcatheter aortic valve implantation (TAVI) with the self-expanding CoreValve (n=28 patients), mechanically expanded Lotus valve (n= 37) or balloon expandable Edwards SAPIEN XT (n=18) and Edwards SAPIEN 3 (n= 31). The cover index of the THV was calculated as the percentage difference of the nominal prosthesis size and annulus diameter measured using CT. Intraprocedural transesophageal echocardiography (TEE) was performed to determine the size of the THV inflow after implantation. The shrinking index was calculated as the percentage of the difference between the inflow size by TEE and the nominal prosthesis size divided by prosthesis size. Results: Cover index per CT assessment before TAVI was 18 ± 7% for CoreValve, 2 ± 4% for Lotus, 9 ± 5% for Edwards SAPIEN and 4 ± 5% for Edwards SAPIEN 3 (ANOVA p < 0.001, Corevalve was significantly larger than the others). Compared with aortic annulus diameter measured using TEE in long axis view, the overestimation increased to 28 ± 9% for CoreValve, 12 ± 8% for Lotus, 18 ± 12% for Edwards SAPIEN and 12 ± 8% for Edwards SAPIEN 3 (ANOVA p < 0.001, Corevalve was significantly larger than the others). Conversely, the shrinking index after TAVI was -31 ± 6% for CoreValve, -20 ± 5% for Lotus, -22 ± 6% for SAPIEN XT and -19 ± 5% for SAPIEN 3 (ANOVA p < 0.001, Corevalve was significantly larger than the others). The interobserver variability (relative difference) of TEE in measuring the aortic annulus and prosthesis inflow was 6 ± 5% and 7 ± 5% respectively. Conclusion: The shrinking index determines the degree of THV underexpansion after TAVI and can be reliably measured with TEE. The self-expanding CoreValve tended to be under-expanded the most, indicated by the largest shrinking index, while the under-expansion degree was comparable between Lotus valve, SAPIEN XT and SAPIEN 3. The clinical implications of the shrinking index requires further study.