Thrombogenic influence of biomaterials in patients with the Omni series heart valve: Pyrolytic carbon versus titanium

An opportunity to assess the thromboembolic rates caused by the constructio n materials on valve replacements is possible with the Omni series of mecha nical heart valves. The Omnicarbon and Omniscience valves are identical in form but differ in that the Omnicarbon valve is constructed entirely of pyr olytic carbon, whereas the Omniscience valve uses titanium for its housing, the rest of its structure being pyrolytic carbon. The literature was revie wed and a comparison in similar groups of patients was made between these t wo model valves for their thromboembolic rates in the mitral and aortic pos itions. A total of 569 aortic Omnicarbon valves (4,146 patient years [pt yr s.]) had a thromboembolic events (T/E rate) of 0.5% compared with 1.7% for 468 aortic Omniscience (1,552 pt yrs); p < 0.0001. A total of 298 mitral Om nicarbon valves (3,333 pt yrs) had a T/E rate of 1.6% compared with 2.6% fo r 716 mitral Omniscience valves (2,134 pt yrs), p < 0.001. There was no dif ference in the anticoagulation management between the two model valves alth ough the Omniscience valve required higher prothrombin or International Nor malized Rate maintenance levels, which resulted in higher bleeding rates am ong patients with Omniscience valves.