OBJECTIVES: Small-sized bioprosthetic valves are sometimes associated with suboptimal hemodynamic performance, leading to a patient-prosthesis mismatch. Trifecta pericardial valves are designed to improve hemodynamic performance. The purpose of this study was to investigate the hemodynamic properties of small-sized Trifecta valves and their efficacy in preventing a patient-prosthesis mismatch. METHODS: This was a retrospective analysis of 108 patients undergoing surgical aortic valve replacement with a Trifecta valve of 23 mm or less in a single Japanese institution. The hemodynamic performance was evaluated with an echocardiography examination in all patients after surgery, and the development of a patient-prosthesis mismatch was judged with the measured in vivo indexed effective orifice area. RESULTS: There was one early and seven late mortalities. There were no valve explants due to structural valve deterioration. Postoperative mean pressure gradients of 19-, 21-, and 23-mm valves were 15.1, 11.4, and 9.0 mmHg, respectively. The effective orifice area of 19-, 21-, and 23-mm valves was 1.41, 1.69, and 1.78 cm2, respectively. Patient-prosthesis mismatch occurred in 14 patients (1 severe and 13 moderate) and the incidence was 13.0% (15.4% in 19 mm, 18.0% in 21 mm, and 3.3% in 23 mm). CONCLUSIONS: The small-sized Trifecta valves showed excellent hemodynamic performance and were associated with a low incidence rate of patient-prosthesis mismatch.