An implantable prosthetic heart valve configured to be radially collapsible to a collapsed or crimped state for introduction into the body on a balloon delivery catheter and radially expandable using a balloon of the balloon delivery catheter to an expanded state for implanting the prosthetic heart valve at a native aortic valve, the prosthetic heart valve comprising: a radially collapsible and expandable annular frame, the frame having a plurality of angularly spaced, axial struts (18, 30) that are interconnected by a plurality of rows of circumferential struts (20, 22, 24); wherein at least one row of circumferential struts (20, 22, 24) include pairs of circumferential struts extending between two axial struts (18, 30), wherein each strut of the pair of circumferential struts has one end connected to a respective axial strut (18 30) and another end interconnected to an adjacent end of the other strut of the same pair of circumferential struts by a crown portion such that a gap exists between the adjacent ends of the circumferential struts; an annular skirt member positioned inside of and secured to the frame; the skirt member having an outflow edge having an undulated shape, following the shape of one row of the plurality of rows of circumferential struts (20, 22; 24), the skirt member being secured inside the frame along the outflow edge to the one row of the plurality of rows of circumferential struts (20; 22; 24) with sutures; and a leaflet structure comprising a plurality of leaflets, the leaflet structure having a scalloped inflow edge portion secured to an inner surface of the skirt member, each leaflet having an outflow edge, a curved inflow edge and two side flaps extending between respective ends of the outflow edge and the inflow edge, wherein each side flap is secured to an adjacent side flap of another leaflet to form commissures of the leaflet structure, each commissure being attached to one of the axial struts (18, 30), and wherein the scalloped inflow edge portion of the leaflet structure is sutured to an inner surface of the skirt member along a scalloped suture line. a radially collapsible and expandable annular frame, the frame having a plurality of angularly spaced, axial struts (18, 30) that are interconnected by a plurality of rows of circumferential struts (20, 22, 24); wherein at least one row of circumferential struts (20, 22, 24) include pairs of circumferential struts extending between two axial struts (18, 30), wherein each strut of the pair of circumferential struts has one end connected to a respective axial strut (18 30) and another end interconnected to an adjacent end of the other strut of the same pair of circumferential struts by a crown portion such that a gap exists between the adjacent ends of the circumferential struts; an annular skirt member positioned inside of and secured to the frame; the skirt member having an outflow edge having an undulated shape, following the shape of one row of the plurality of rows of circumferential struts (20, 22; 24), the skirt member being secured inside the frame along the outflow edge to the one row of the plurality of rows of circumferential struts (20; 22; 24) with sutures; and a leaflet structure comprising a plurality of leaflets, the leaflet structure having a scalloped inflow edge portion secured to an inner surface of the skirt member, each leaflet having an outflow edge, a curved inflow edge and two side flaps extending between respective ends of the outflow edge and the inflow edge, wherein each side flap is secured to an adjacent side flap of another leaflet to form commissures of the leaflet structure, each commissure being attached to one of the axial struts (18, 30), and wherein the scalloped inflow edge portion of the leaflet structure is sutured to an inner surface of the skirt member along a scalloped suture line.