Late clinical outcomes after mechanical aortic valve replacement for aortic stenosis: old versus new prostheses

Heemoon Lee, Kiick Sung, Wook Sung Kim, Dong Seop Jeong, Joong Hyun Ahn, Keumhee Chough Carriere, Pyo Won Park


Background: The study aimed to evaluate the late clinical outcomes of new-generation mechanical valves for severe aortic stenosis (AS) compared with old mechanical valves.
Methods: We retrospectively reviewed data from 254 patients with severe AS, who underwent primary mechanical aortic valve replacement from 1995 to 2013. Patients were classified into two groups: old-valve group (n=65: 33 ATS standard, 32 Medtronic-Hall) and new-valve group (n=189: 113 St. Jude Regent, 46 On-X, 30 Sorin Overline). Median patient age was 58 years (Q1–Q3: 52–61). With propensity score matching based on demographic information, 56 patients in the old-valve group were matched with 177 patients in the new-valve group. The median follow-up duration was 91 months (Q1–Q3: 48–138).
Results: Cardiac-related mortality and hemorrhagic events were significantly lower in the new-valve group (P=0.047 and P=0.032, respectively). The median international normalized ratio (INR) at follow-up was significantly higher in the old-valve group [2.23, Q1–Q3: 2.14–2.35 (old-valve group); 2.08, Q1–Q3: 1.92–2.23 (new-valve group), P<0.001]. The incidence of prosthesis-patient mismatch (PPM) was significantly higher in the old-valve group (P<0.001). Multivariate analysis of the total population revealed that PPM was a significant risk factor for cardiac-related events [hazard ratio (HR) =5.279, 95% CI, 1.886–14.561, P=0.002] and showed higher trend of increasing mortality (HR =3.082, P=0.076).
Conclusions: New mechanical prostheses showed a better hemodynamic performance and lower incidence of PPM. Anticoagulation strategy to lower the target INR in patients with new mechanical valves may improve late outcomes by reducing hemorrhagic events.