Balloon-expandable prostheses for transcatheter aortic valve replacement.

The implantation of a transcatheter heart valve (THV) through a balloon-expandable system played a major role in the early stages of transcatheter aortic valve replacement (TAVR). The technology consists of sewing a foldable biological cardiac valve inside a metallic stent frame, and then crimping the device into a balloon in order to implant the valve at the level of the aortic annulus through balloon inflation. The use of balloon-expandable valves underwent a rapid expansion in the years following the pioneering experience of 2002, and recent large multicenter trials and registries have confirmed the safety and efficacy of TAVR using balloon-expandable valves. The randomized Placement of Aortic Transcatheter Valves (PARTNER) trial showed both the superiority and non-inferiority of TAVR with the balloon-expandable Edwards-Sapien system compared to medical treatment (non-operable patients) and surgical aortic valve replacement (high risk patients), respectively. Balloon-expandable valves have been associated with excellent hemodynamic results (residual mean gradient <15 mm Hg in most cases), though residual paravalvular aortic regurgitation is frequent (trivial or mild in the majority of patients, moderate or severe in <10%). Valve durability studies with up to 5-year follow-up have shown maintained valve hemodynamics over time with only a minimal decrease in valve area and no increase in aortic regurgitation. Future improvements in the balloon-expandable THV technology such as implementing anti-paravalvular leak features (ex. Sapien 3 valve), and showing its efficacy for the treatment of non-high risk patients (ongoing PARTNER II trial) will probably lead to broader use in a lower risk population in the near future.