Aortic valve replacement with 17-mm mechanical prostheses: is patient-prosthesis mismatch a relevant phenomenon?

We sought to evaluate the long-term performance of a consecutive cohort of patients implanted with a 17-mm bileaflet mechanical prosthesis.

Between January 1995 and December 2005, 78 patients (74 women, mean age=71±12 years) underwent aortic valve replacement with a 17-mm mechanical bileaflet prosthesis (Sorin Bicarbon-Slim and St. Jude Medical-HP). Preoperative mean body surface area and New York Heart Association class were 1.6±0.2 m2 and 2.6±0.8, respectively. Preoperative mean aortic annulus, indexed aortic valve area, and peak and mean gradients were 18±1.6 mm, 0.42 cm2/m2, 89±32 mm Hg, and 56±21 mm Hg, respectively. Patients were divided into two groups, according to the presence (group A, 29 patients) or absence of patient-prosthesis mismatch (group B, 49 patients). Patient-prosthesis mismatch was defined by an indexed effective orifice area less than 0.85 cm2/m2.

Overall hospital mortality was 8.8%. Follow-up time averaged 86±44 months. Actuarial 5-year and 10-year survival rates were 83.7% and 65.3%, respectively. The mean postoperative New York Heart Association class was 1.3±0.6 (p<0.001). Overall indexed left ventricular mass decreased from 163±48 to 120±42 g/m2 (p<0.001), whereas average peak and mean prosthesis gradients were 28±9 mm Hg and 15±6 mm Hg, respectively (p<0.001). Early and long-term mortality were similar between the two groups as well as long-term hemodynamic performance (mean peak gradient was 28 mm Hg and 27 mm Hg in group A and B, respectively, not significant); left ventricular mass regression occurred similarly in both groups (indexed left ventricular mass at follow-up was 136±48 and 113±40 in group A and B, respectively; not significant).

Selected patients with aortic stenosis experience satisfactory clinical improvement after aortic valve replacement with modern small-diameter bileaflet prostheses.