Replacement heart valve having improved collapsible seal

A prosthetic cardiac valve for transcatheter delivery comprising:

• a frame with an axial inflow end and an axial outflow end,
• a plurality of leaflets arranged on the frame, and
• a sealing skirt for reduction or prevention of paravalvular leakage, the sealing skirt comprising one or more sealing formations that are arranged on a radially outer surface of the sealing skirt and project radially outward from the radially outer surface,
• wherein the prosthetic cardiac valve is compressible to a compressed state for delivery and expandable to an expanded state for implantation;
• wherein, at least in the expanded state, at least one of the one or more sealing formations is shaped and arranged such that, at each axial position along the sealing skirt covered by the one or more sealing formations, the percentage of the radially outer surface occupied by the one or more sealing formations, in cross-section, is less than 100%.