thats true, but its all a matter of understanding what those odds are.I sure hope to have my mechanical valve for a lifetime, but it seems everything regarding this issue is a crapshoot, which is unfortunate
Lets look at Roulette, some bets are nearly 50:50 (like black or red) other bets are much less likely (any particular number).
With a mechanical the chances of needing it replaced if you don't have a possibility of an aneurysm (so, say you are also having it fixed at the same time) are very low. No matter what the time scale.
With a tissue prosthesis the chances of it having SVD move towards a certainty as you approach 20 years.
As you already know, outcomes with a mechanical are determined by how well you manage ACT, outcomes with tissue prosthesis are more stochastic and management is only by surgery (which included TAVI).
lastly life itself is a gamble ... play the hand and see where it goes