Original article
Cardiovascular
Multicentered European Study on Safety and Effectiveness of the On-X Prosthetic Heart Valve: Intermediate Follow-Up

https://doi.org/10.1016/j.athoracsur.2006.08.010Get rights and content

Background

This study was performed to determine the safety and effectiveness of the On-X valve, a novel mechanical valve substitute.

Methods

Eleven centers participated in a European, multicentered, longitudinal, nonrandomized study of the On-X valve performance. Isolated aortic or mitral valve replacement with an On-X valve was studied in 301 patients. Aortic valve replacement was performed in 184 patients (average follow-up, 5.0 years), whereas mitral valve replacement was performed in 117 patients (average follow-up, 4.4 years).

Results

In patients with aortic valve replacement, mean transvalvular pressure gradients ranged from 8.3 to 4.7 mm Hg and effective orifice areas from 1.5 to 2.7 cm2, for 19-mm through 25-mm valves, respectively. After mitral valve replacement, mean gradient was 4.2 mm Hg and effective orifice area by pressure half-time was 2.6 cm2 regardless of valve size. Hemolysis was low, with postoperative serum lactate dehydrogenase at 225 ± 41 IU (mean ± standard deviation) or 253 ± 65 IU, after aortic valve replacement or mitral valve replacement, respectively (upper normal value, 250 IU). At 1 year or greater postoperatively, 91.6% of patients after aortic valve replacement and 84.6% after mitral valve replacement were in New York Heart Association functional class I or II. Adverse event rates in percent per patient-year after aortic valve replacement or mitral valve replacement were thromboembolism, 0.88 or 1.76; thrombosis, 0.11 or 0.20; bleeding, 0.77 or 1.96, respectively. Late mortality was 1.97% or 2.55%, respectively.

Conclusions

At the intermediate follow-up, the On-X valve exhibited improved hemodynamics, low hemolysis with in-range lactate dehydrogenase, and low adverse event rates, particularly in the aortic position.

Section snippets

Patients and Methods

A prospective, nonrandomized, multicentered clinical trial was conducted at 11 centers in Europe to determine the safety and effectiveness of the On-X valve (Medical Carbon Research Institute, Austin, TX; Table 1). The study was approved by the ethics committee of each participating center. All patients included in the study had severe aortic or mitral valve disease requiring valve replacement on the basis of clinical, echocardiographic, and cardiac catheterization data. All patients signed an

Results

Early (30-day) and late postoperative events are presented in Table 3, Table 4, respectively.

Comment

The major concern for mechanical valves is the long-term need for warfarin-based anticoagulation as it relates to the thrombogenic potential of these valves and to bleeding from erroneously high anticoagulant dosage. In this study, the patients were maintained on permanent anticoagulation with warfarin at a slightly higher level than now recommended owing to the change of anticoagulation recommendations for bileaflet valves in 1998, while this study was ongoing [7]. We did not lower

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