Osaka University

To establish the safety and effectiveness of surgical aortic valve replacement (SAVR) in patients with isolated severe, calcific aortic stenosis who are at low surgical risk.

Background In 2018, transcatheter aortic valve in surgical aortic valve (TAV-in-SAV) in high risk patients was approved for the treatment of bioprosthetic valve dysfunction due to aging, for which valve replacement had been selected. It has been reported that early and mid-term results of TAV-in-SAV differ depending on the sizes of the original surgical bioprosthetic valves. Especially, the prognoses of TAV-in-SAV in patients with surgical bioprosthetic valves of ≤21 mm in size are reported to be poor in the United States and Europe. Bioprosthetic valves of ≥21 mm in size are thus tended to be used also in Japan after the annular was enlarged in the initial surgery as needed. The patient group in the above-mentioned report, however, consisted of larger patients (with the mean body surface area of 1.85 m2). It has therefore been unknown whether the above report applies to smaller patients in Japan. Furthermore, in terms of the surgical results for valvular disease, not only short-term results, but also repeat surgery avoidance rate, as well as medium- and long-term results, including the occurrence rate of complications related to artificial valves, are important factors, but the characteristic of this disease, the number of cases at each facility is not that large, so there have been no comprehensive reports of TAV-in-SAV in Japan. Accordingly, the investigators will investigate TAV-in-SAV performed at Osaka University as well as multiple centers in Japan to: understand the facts; assess the appropriateness of the evaluation of the above-mentioned paper; and examine early and mid-term treatment results of TAV-in-SAV in patients with narrow bioprosthetic valves, which are specific to Japanese patients. The investigators also plan to study early and mid-term treatment results of TAV-in-SAV using a self-expanding valve because self-expanding valves generally produce favorable hemodynamics in narrow bioprosthetic valves.
Study Objectives i. To study early and mid-term results of transcatheter aortic valve implantation in patients with aortic bioprosthetic valve dysfunction (hereinafter referred to as TAV-in-SAV).
ii. To compare clinical results, including hemodynamics, of TAV-in-SAV between small aortic bioprosthetic valves (19 or 21 mm in size) and aortic bioprosthetic valves of other sizes.
iii. To compare clinical results, including hemodynamics, of TAV-in-SAV between a self-expanding valve and a balloon-expandable valve.
Study Methods i. Study design A multicenter, retrospective, observational study using existing data. ii. Endpoints
Study endpoints are as follows:
Primary endpoint: Death during the observation period The mortality among all patients registered in this study will be estimated with the Kaplan-Meier method.
Secondary endpoints: Analyses of major cardiac and cerebral events (MACCE) and factors associated with death. The rate of freedom from MACCE among all patients registered in this study will be estimated with the Kaplan-Meier method. Factors associated with death will be explored using a Cox proportional hazards model.
Hemodynamics and events including death and MACCE will also be compared between aortic bioprosthetic valves of 19 or 21 mm in size and those of other sizes.
In addition, hemodynamics and events including death and MACCE will be compared between a self-expanding valve (Evolut) and a balloon-expandable valve (SAPIEN) using propensity-matching analyses.