Does the use of stentless aortic valves in a subcoronary position prevent patient-prosthesis mismatch for small aortic annulus?

Objective: Freestyle stentless bioprostheses have shown excellent hemodynamic performance. However, small size subcoronary implants have yet to prove their clinical usefulness. The aim of this study was to determine the incidence of patient-prosthesis mismatch [PPM = Indexed Effective Orifice Area (iEOA) <= 0.85 cm(2)/m(2)] after aortic valve replacement (AVR) with 19-mm and 21-mm stentless bioprostheses and to evaluate clinical and hemodynamic outcomes. Methods: From January 1993 to December 2000, 419 patients who had undergone Freestyle bioprostheses implantation were prospectively followed. Sixty-eight patients (16%) received a 19-21-mm prosthesis. The EOA was calculated and indexed to the patient's body surface area to obtain the iEOA. Clinical as well as echographic measures were recorded at discharge and at one and five years. Results: PPM was present in 91% and 80% of patients with 19-mm and 21-mm prostheses, respectively. Severe mismatch (iEOA <= 0.65 cm(2)/m(2)) was present in 58% and 17%. Mean gradients at discharge were 22 +/- 11 mmHg for the 19-mm prostheses and 14 +/- 7 mmHg for the 21-mm prostheses. Perioperative mortality was 33% (4/12 pts) for 19-mm prosthesis and 7% (4/56 pts) for 21-mm prostheses. Five-year actuarial survival was 58% for patients with 19-mm prosthesis and 82% for patients with 21-mm prosthesis (p = 0.04). Conclusion: AVR with small size Freestyle subcoronary implants is associated with a high incidence of PPM and high mortality.