My take on this...
Please bear with me, as the beginning parts of this include information geared more to aortic valve work than mitral. But I will clarify it at the end.
The Freestyle (Medtronic preserved porcine) does seem to be a standout niche product, with a big niche in aortic replacements. It's based on the earlier, successful Hancock models, which are still available. It has all the technical extras (anticalcification treatments, nondamaging preservation technique) you'd look for in any up-to-date tissue valve, but also does that aortic root replacement when you need it, whereas other treated tissue valves need to be sewn to a dacron velour or similar sleeve to do any aorta replacement.
(Note: Some mechanical valves, like the St. Jude models, can come already integrated with a fabric tube for root replacements along with the valve. On-X currently doesn't, and has to be mated to a sleeve while you're on the table.)
For a while, it was popular to use the Freestyle in place of a stented model, such as the Perimount Magna (Carpentier-Edwards manufactured bovine pericardium) or the Mosaic (Medtronic preserved porcine), even when the root didn't require replacement. They needed to be individually cut at operation time for the individual and replaced more tissue than the simple valves (the tissue they're in holds their shape, like a wagon wheel, rather than a stent keeping them round). I've not read as much about the technique recently, but I'm sure it's still being used. A number of our members had this done.
The Toronto, marketed by St. Jude in the US, was a stentless porcine valve conceptually somewhat similar in approach to the Freestyle, but has not been sold in the US with any modern anticalcification treatments, and seems to achieve only about a 10-12-year lifespan without them, despite belief that it would go longer.
The CEPM (Magna) has a stent, but it can be placed supraannularly (above the shelf the valve is usually tied to), which allows one size larger valve (and thus one size larger opening - minus the stent width). The Mosaic has a half-thickness stent which maximizes the annulus size within the normal placement area. Their performance is very close.
Those three are the current, main candidates in the US for aortic repalcements. Within a year, St. Jude will likely have an anticalcification-treated porcine valve model available in the US as well. It has had prolonged testing in Europe.
For mitral work, the CEPM and the Mosaic are the current top tissue dogs. Neither will last as long in the mitral position as they will in the aortic. They are anticipated to be nearly equivalvent in life cycle, but there is longer-term data available for the CEPM at this time, so it is the one with the actual track record. Data from the Mosaic will be forthcoming soon, if it's not here already for the mitral position*. However, you wouldn't go wrong with either one.
*Just realized Scooby06 has data for the Mosaic. The 10-year data is already better than anything I've read before.
Best wishes,
