This study compares the implantation characteristics and the hemodynamic performance of the new Carpentier-Edwards Perimount Magna (CEPM) xenograft with those of the standard Perimount (CEPS) valve in the aortic position. Eighty consecutive patients surviving an aortic valve replacement with either the CEPS valve (n=40) or the CEPM prosthesis (n=40) in the supra-annular position were retrospectively reviewed. One year follow-up was complete and hemodynamic performance assessed by Doppler echocardiography. The mean valve size implanted was 21.3+/-1.7 mm (CEPS) vs. 22.2+/-1.8 mm (CEPM). The average mean pressure gradient was 13.6+/-5.1 mmHg in the CEPS group and 9.6+/-3.3 mmHg in the CEPM group (P<0.0001). Mean and peak gradients were slightly lower and the effective orifice areas (EOA) were larger for the Magna prosthesis than for the comparable standard valves: 19 mm (1.58+/-0.2 vs. 1.28+/-0.1 cm(2)), 21 mm (1.90+/-0.4 vs. 1.69+/-0.4 cm(2)), 23 mm (2.07+/-0.3 vs. 1.86+/-0.3 cm(2)), 25 mm (2.30+/-0.1 vs. 1.89+/-0.5 cm(2)). The average indexed EOA was statistically different between groups (CEPS 0.98+/-0.21 cm(2)/m(2) vs. CEPM 1.20+/-0.25 cm(2)/m(2)). Patient-prosthesis mismatch (indexed EOA<or=0.85 cm(2)/m(2)) was present in 40.7% (CEPS) vs. 16.6% (CEPM) of the patients with valve sizes <or=21 mm. Our study demonstrates that the Magna prosthesis significantly reduces the incidence of patient-prosthesis mismatch when compared to the standard Perimount valve in the aortic position.