MCRI On-X has contended that as a result of their non-silicon alloyed pyrolytic carbon and because of the shape and length of the orifice, there are inherent thromboembolic advantages to the On-X mechanical valve.  The mid to long term studies of the On-X valve as presented in the journals summarized here do not support this.  Collectively they show an acceptable, but unremarkable rate of complications at normal to historically higher INR levels. It really begs the question: Shouldn’t a valve touted as being likely suitable for low or no levels of anticoagulation have amazing results at regular INR levels?

The Truth About Non-silicone Carbon

Actual SEM study photo of non-alloyed exposed to human blood.

Platelets still adhere and aggregate, no magic!

Comparative Replacement Results of the ATS Open Pivot® Aortic and Mitral at Lower INR’s vs. On-X Aortic and Mitral at Regular INRs

•  Single-Center Experience with the On-X Prosthetic Heart Valve between 1996 and 2005 - Tossios, et al.  [Summary]
The Journal of Heart Valve Disease.  2007; 16(5):551-557. Link to PubMed-PMID 17944128

• North American Multicenter Experience with the On-X Prosthetic Heart Valve -. McNicholas, et al. [Summary]
The Journal of Heart Valve Disease.  2006; 15:73-79. Link to PubMed-PMID 16480015

• The On-X Prosthetic Heart Valve at Five Years - Moidl, et al. [Summary]
The Annals of Thoracic Surgery. 2002; 74:S1312-7. Link to PubMed-PMID 12400807

References

1. Emery RW, Krogh CC, et al.  Five-Year Follow Up of the ATS Mechanical Heart Valve.  J of Heart Valve Disease 2004; 13:231-238
2. Aoyagi S, Hori H, et al.  Mid-term Results of Valve Replacement with the ATS Valve: A Seven-Year Follow Up.  J of Heart Valve Disease 2007; 16:267-274
3. Hata M, Shiono M, Orime Y et al.  Mid-term results of ATS open pivot bileaflet mechanical prosthetic heart valve.  Ann of Thorac Cardiovasc Surg 2000; 6:34-38
4. Emery RW, Van Nooten GI, Tesar PJ.  The initial experience with the ATS medical mechanical cardiac valve prosthesis.  Ann Thorac Surg 2003; 75:444-52
5. Koertke H, Koefer R.  International normalized ratio self management after mechanical heart valve replacement:  Is an early start advantageous?  Ann Thorac Surg 2001; 72:44-48
6. Baykut D,Grize L, et al.  Eleven-Year Single-Center Experience with the ATS Open Pivot Bileaflet Heart Valve.  Ann Thoracic Surg 2006; 82:847-52
7. Stefanidis C, Nana A, et al.  10-Year Experience With the ATS Mechanical Valve in the Mitral Position.  Ann Thoracic Surg 2005; 79:1934-8
8. Van Nooten GJ, Van Belleghem Y, et al.  Lower-Intensity Anticoagulation for Mechanical Heart Valves: A new Concept with the ATS Bileaflet Aortic Valve.  J of Heart Valve Disease.  2003; 12:495-502
9. Baykut D, Grize L, et al.  Eleven-Year Single-Center Experience with the ATS Medical Mechanical Cardiac Valve Prosthesis.  Ann Thoracic Surg 2006; 82:847-52
10. Sefanidis C, Nana AM, et al.  10-Year experience with the ATS mechanical valve in the mitral position.  Ann Thoracic Surg 2005; 79:1934-1938