Background: Optimal valve sizing provides improved results in transcatheter aortic valve replacement. Operators hesitate about the valve size when the annulus measurements fall into borderline area. Our purpose was to compare the results of borderline versus non-borderline annulus and to understand the impact of valve type and under or oversizing.

Methods: Data from 338 consecutive transcatheter aortic valve replacement procedures were analyzed. The study population was divided into 2 groups as “borderline annulus” and “non-borderline annulus.” Balloon expandable valves already have a grey zone definition. Similar to balloon expandable valves, annulus sizes that are within 15% above or below the upper or lower limit of a particular self-expandable valve size are defined as the “borderline annulus” for self-expandable valves. The borderline annulus group was also divided into 2 subgroups according to the smaller or larger valve selection as “undersizing” and “oversizing.” Comparisons were made regarding the paravalvular leakage and residual transvalvular gradient.

Results: Of these 338 patients, 102 (30.1%) had a borderline and 226 (69.9%) had a non-borderline annulus. Both the transvalvular gradient (17.81 ± 7.15 vs. 14.44 ± 6.27) and the frequency of paravalvular leakage (for mild, mild to moderate, and moderate, 40.2%, 11.8%, and 2.9% vs., 18.8%, 6.7%, and 0.4%, respectively) were significantly higher in the borderline annulus than the non-borderline annulus group (P <.001). There were no significant differences between the groups balloon expandable versus self-expandable valves and oversizing versus undersizing regarding the transvalvular gradient and paravalvular leakage in patients with borderline annulus (P >.05).

Conclusion: Regardless of the valve type and oversizing or undersizing, borderline annulus is related to significantly higher transvalvular gradient and paravalvular leakage when compared to the non-borderline annulus in transcatheter aortic valve replacement.