Undersizing but overfilling eliminates the gray zones of sizing for transcatheter aortic valve replacement with the balloon-expandable bioprosthesis

•Transcatheter heart valve size selection is still challenging.•The overlap between two different prosthesis sizes for borderline annuli remains.•Undersizing but overfilling improves sizing in borderline annulus cases.•Undersizing but overfilling decreases the postprocedural THV-pressure gradient.•Prospective studies are needed considering the TAVR expansion to younger patients.