Successful treatment of failing biological prosthesis because of "Stent creep" with valve-in-valve transcatheter aortic valve implantation.

INTRODUCTION: Stent creep is an uncommon mode of structural deterioration of bioprosthetic heart valves defined by a permanent inward deflection of the stent posts. This may occur because of valve over-sizing and leads to intrinsic valve stenosis. It has been described in older generation of bioprosthesis and was thought not to occur in modern devices.

METHODS: We describe three patients who were referred for bioprosthetic valve degeneration with presumed aortic stenosis. Investigations demonstrated mid valvular gradient predominantly because of stent creep. We performed valve-in-valve TAVI with Edward SAPIEN prosthesis.

RESULTS: Median age was 84 and logistic EuroSCORE 34.4. All patients had degenerated bioprosthesis with mean implant duration of 5.6 years. Two patients had Carpentier Edwards Perimount prosthesis (19 and 23 mm) and one patient had a Mitroflow (21 mm). Mean gradients were 33, 54, and 22 mm Hg. About 23 mm Edward SAPIEN valve was implanted in all cases with immediate improvement in haemodynamics with mean gradient reduction to 10, 17, and 8 mm Hg, respectively. The mean aortic valve area increased from 0.63 to 1.76cm(2) . There were no serious adverse events. The patients improved from NYHA III/IV to I/II post procedure and remain well at median follow-up of 24-months.

DISCUSSION: Stent creep is an uncommon mode of structural deterioration in bioprosthetic heart valves. It has been described in the previous generation of bioprosthesis. It is important to distinguish leaflet dysfunction and stent creep. By forcing the stent posts outwards a balloon expandable TAVI device can be used to treat this condition.