Aortic annulus diameter and valve design each determine the valve size implanted.

BACKGROUND AND AIM OF THE STUDY: The study aim was to compare the sizing characteristics and hemodynamics of the Medtronic Mosaic Ultra porcine and Carpentier-Edwards PERIMOUNT Magna bovine pericardial bioprosthetic stented aortic valves in relation to the patient's true aortic annulus size.

METHODS: In this prospective multicenter randomized study, data acquired perioperatively and at six months postoperatively were collected. Following aortic valve excision and debridement, the annulus was measured by blinded sizers prior to the randomization of 141 patients (Ultra, n=72; Magna, n=69).

RESULTS: The median patient age was 75 years, and 89% of the patients had aortic stenosis. A good left ventricular function was present in 75% of patients, and the EuroSCORE-predicted mortality was 9%. Concomitant procedures (coronary artery bypass grafting, mitral/tricuspid repair, septal myectomy, modified Maze) were performed in 61% of patients. The in-hospital mortality was 3%, and at six months postoperatively 96% of the patients were NYHA class I or II, with no intergroup differences. The mean 'true aortic annulus' size was 23.0 +/- 1.4 mm for the Ultra valve, and 22.6 +/- 1.8 mm for the Magna valve (p = NS). The implanted labeled valve size was > or = 23 mm for 83% of Ultra valves, and for 52% of Magna valves (p < 0.01), and smaller than the measured true aortic diameter (44% Magna versus 33% Ultra). The mean echo gradients were lower with Magna valves (11 +/- 6 mmHg) than with Ultra (17 +/- 6 mmHg; p < 0.01), while the effective orifice area (EOA) was higher with Magna than with Ultra (1.6 +/- 0.4 versus 1.4 +/- 0.4 ; p < 0.01). Both groups showed a similar left ventricular mass regression (Ultra -48 +/- 83 g; Magna -42 +/- 70 g). Trivial to moderate regurgitation was noted in 24% of Ultra valves compared to 48% of Magna valves (p < 0.01).

CONCLUSION: Selection of the Ultra bioprosthetic valve allowed the implantation of larger valve sizes. However, when compared to the 'true aortic annulus', the Magna was associated with lower transprosthetic gradients and larger EOAs. The longer term significance of these observations remains inconclusive in terms of bioprosthesis selection, however.