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- Dec 5, 2020
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That is what my surgeon told me as well. In my pre-surgical consult, I was deciding between On-x and St Jude mechanical. He said he preferred the St Jude due to its long history and because it was less bulky- showed me a sample of each valve. He said the choice was mine and he's be happy to go with either valve. But, he said that if we go with the On-x, he will not have me on the low INR range, as that was just marketing. He said that he and his colleagues have major issues with the PROACT Trial, the small trial which was used to get approval for the lower INR range for On-x, and that it was dangerous to have INR that low. I ultimately went with St Jude.
I believe On-x is also a very good valve, but we have seen several members have clots at the lower INR range. If one reads the Proact Trial, this would be expected. Many more clots in the lower INR range, but because it was such a small sample size, it did not reach statistical significance. This allows them to say "no differences in the rates of TE and thrombosis events", which is not an accurate statement. There was a big difference, just not reaching a P value to achieve statistical significance. As @pellicle noted above TE and thrombosis was 2.96%/pt-yr in the test group versus 1.85%/pt-yr in the standard group, p = 0.178. This represents 60% more TE and thrombosis in the study group, verses the standard INR control group. This should have been a big red flag.
This low P value was almost certainly due to the small number of individuals in the study. Some might call this statistical slight of hand. Even though it did not have enough participants to reach statistical significance, the much higher rate of TE and thrombosis in the study suggests that there may be a major problem there which should have warranted further study, with more participants, before this low INR range was approved. Somehow Cryolife prevailed in getting the FDA to approve the low range without further study. Very questionable.
Other issues with the Proact Trial:
-The participants self tested. This has shown to reduce events drastically, by about 50%. Yet the low INR protocal was approved without requiring self testing. How was this overlooked?
-The low INR range was 1.5 to 2.0, but it would appear that they targeted closer to 2.0 for the study. The average INR for the low INR study group was 1.89. If the desire is to stay in a range consistent with the study, it probably should be more like 1.7 to 2.2 for patients to target. But, keep in mind, even at the 1.89 average INR range, they still had 60% more TE and Thrombosis events. So, I think that my surgeon had it right when he cautioned about the low INR range.
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