Does anybody know whether the Plavix focus on the On-X is a reflection of the On-X's state-of-the-art lowest propensity to form clots, as opposed to a state-of-the-art eagerness on its manufacturer's part to push the envelope and study the acceptability of lower ACT approaches?
Put another way, is there independent evidence that the On-X is better than the competition in the factors that require ACT?
It seems like spiffy technology, and I've been "connecting the dots" to conclude that it was the best mechanical valve, but it's recently occurred to me that I'd never actually seen a study that established that -- just design-and-materials "reasons to believe" (from the manufacturer), and the PRESENCE of these tests. . .
I THINK it may be a little of both. It is a very good valve, and is built on learning from the experience of earlier valves, but the oldest ones are just reaching 15 years in people so it will be interesting to read long term studies when they can do them. They also seem to be very good at marketing.
From what I know alot of the reason they were able to do the trials with lower anticoagulation was because of the results from a 2006 study in South Africa that showed good results in poorly anticoagulated population.
http://www.ncbi.nlm.nih.gov/pubmed/16480016
BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the clinical performance of the On-X heart valve in a socioeconomically disadvantaged population. Most patients were from an indigenous, poorly educated and geographically dispersed segment of the population where anticoagulation therapy was generally erratic.
METHODS: Between 1999 and 2004, a total of 530 valves (242 mitral valves, 104 aortic valves, 92 double valves) was implanted in 438 patients (average age 33 years; range: 3-78 years). The most common reason for surgery was rheumatic valve disease (57%), followed by degenerative valve disease (11%) and infective endocarditis (9%). Follow up was 95% complete for a total of 746 patient-years (pt-yr). Among the patient population, 40% were either not anticoagulated or were unsatisfactorily anticoagulated.
RESULTS: Hospital mortality was 2.3%, and none of the hospital deaths was valve-related. Mean (+/- SE) actuarial survival (including hospital deaths) at four years was: AVR 73.8 +/- 8.1%, MVR 83.4 +/- 5.7% and DVR 60.9 +/- 10.3%. Linearized rates (for AVR, MVR and DVR, respectively) for late complications (%/ pt-yr) were: bleeding events 0.6, 1.0, and 2.3; thrombosis 0.0, 0.2, and 0.0; endocarditis 0.6, 1.0, and 2.3; paravalvular leak 0.6, 0.2, and 0.0; systemic embolism 1.1, 1.5, and 3.5. Most systemic emboli were related to infective endocarditis. Among patients there were seven uncomplicated, full-term pregnancies"
The abstract says Among the patient population, 40% were either not anticoagulated or were unsatisfactorily anticoagulated.
I don't know if that means all the time or when they checked their INR ect.
BUT 2 years earlier there was a study by 2 of the same Authors in the same Hospital, that compared the performance of 3 different mechanical valves (Carbomedics, Medtronic Hall and On-X) in the poorly anticoagulated population that didn't show much difference in the Aortic valves.
http://www.ncbi.nlm.nih.gov/pubmed/15383051
"METHODS: In the Carbomedics group 140 valves were implanted in 126 patients (aortic 30, mitral 82, and aortic and mitral 14), 39% were adequately anticoagulated. Follow-up was 89% complete for a total of 216 patient-years. In the Medtronic Hall series 224 valves were implanted in 198 patients (aortic 50, mitral 122, and aortic and mitral 26), 39% were adequately anticoagulated. Follow-up was 93% complete for a total of 459 patient-years. In the On-X series 252 valves were implanted in 200 patients (aortic 44, mitral 104, and aortic and mitral 52), 58% were adequately anticoagulated. Follow-up was 94% complete for a total of 2217 patient-years.
RESULTS: Hospital mortality was 2.4% (3 patients) in the Carbomedics group, 3.9% (9 patients) in the Medtronic Hall group, and 2.0% in the On-X group. None of the hospital deaths were valve-related. The linearized rates for late complications in the mitral position (percent per patient-year) were, respectively, for the Carbomedics (CM), the Medtronic Hall (MH), and On-X valves-thromboembolism: 1.4 (CM), 1.1 (M.H.); 0.0 (On-X); bleeding: 0.0 (CM), 0.4 (MH); 0.0 (On-X); thrombosis: 6.5 (CM), 2.0 (MH); 0.0 (On-X). In the aortic position, the linearized rates of late complications were, respectively-thromboembolism: 0.0 (CM), 1.6 (MH); 2.2 (On-X); bleeding: 1.3 (CM), 1.0 (MH); 0.0 (On-X); thrombosis: 1.3 (CM), 0.0 (MH); 0.0 (On-X).
CONCLUSIONS: There were no significant differences in the performance of the three valves in the aortic position. In the mitral position the linearized rate of valve thrombosis was significantly higher in the Carbomedics group (p = 0.002)."
These are both the Abstracts, so you can't see the details and graphs, I noticed the On-x patients were adequately anticoagulated 58% compared to both the Medtronic and Carbomedic that were only adequately anticoagulated 39% of the time and I don't know if/how they took that into consideration.
Also It would be interesting to know how the St.Jude valves, especially the Regent would do.
I did read a midterm 5 year study on On-X the other day
http://www.ncbi.nlm.nih.gov/pubmed/20546795
RESULTS: Early mortality was 2.5% (n = 10) for aortic valve replacement and 3.2% (n = 9) for mitral valve replacement. Late mortality for aortic valve replacement was 4.8% per patient-year and 6.0% per patient-year for mitral valve replacement. Five-year freedom from major thromboembolism was 96.5% ± 1.2% for aortic valve replacement and 97.7% ± 0.9% for mitral valve replacement. Five-year freedom from hemorrhage was 93.6% ± 1.8% for aortic valve replacement and 95.7% ± 1.5% for mitral valve replacement. Concomitant coronary artery bypass grafting was predictive of major thromboembolism after aortic valve replacement (hazard ratio, 5.3; P = .02) and antithrombotic hemorrhage after mitral valve replacement (hazard ratio, 4.7; P = .03). No other independent predictors of major thromboembolism or hemorrhage were identified. One thrombosed mitral prosthesis was observed after deliberate discontinuation of anticoagulation. The major thromboembolic events occurred with variation of international normalized ratio levels inclusive of subtherapeutic levels. The majority of hemorrhagic events occurred with high international normalized ratio levels.
CONCLUSIONS: The On-X mechanical prosthesis provides favorable intermediate-term results with regard to major thromboembolism and hemorrhage"
I don't know how they compare to other valves at 5 years.
