2.1 Patient Population and Study Design
Between March 2010 and June 2018, 181 consecutive patients who underwent MVR with a bioprosthetic valve were identified from the institutional database at Saitama Medical Center, Jichi Medical University. As per the inclusion criteria, we included patients who underwent bioprosthetic MVR with or without concomitant procedures. We excluded 53 patients in whom the dominant valve dysfunction was MS, and those without preoperative or postoperative echocardiographic data were missing. Finally, 128 patients were included. The patient’s medical records were reviewed. Emergency surgery was defined as an operation performed within 24 hours of hospitalization.
Doppler transthoracic echocardiography was performed at discharge. The estimated EOA of the implanted mitral valve was calculated using the formula: 220/pressure half-time (PHT). The effective orifice area index (EOAI) was defined as the bioprosthetic EOA/body surface area (BSA), and PPM was defined as an EOAI was ≤ 1.2 cm2/m2, as described in the previous report.12
Follow-up data were obtained from the clinical records or via telephone interview. The follow-up rate was 98.4%; the patient status was confirmed in 126 patients at least 1 year postoperatively, excluding those who died within a year postoperatively. The mean follow-up period was 4.4 ± 2.2 years. The study protocol was approved by the Institutional Review Board of Jichi Medical University (January 15 2020, S19-123).