Transcatherter Aortic Valve Replacement (TAVI or TAVR) - A Developing Technology

by Dr. S. Russell Vester, MD 13. July 2014 12:41

dr. s. russell vester

There is a lot of buzz right now in the cardiac surgery and cardiology literature about replacing the aortic valve without opening the chest. Certainly an attractive concept if you’re the recipient, but at what risk? Conventional surgical practice, whether done through the middle of the chest or small incision just off the middle of the chest, involves the use of the heart-lung machine and is without question a more involved recovery. This is the down side on which everyone focuses and cardiologists, more intent on marketing than the ethical advancement of a still investigational treatment tool, trumpet.

Transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR) can be done either though a catheter run up through the big artery in your groin that feeds your leg, or, if that blood vessel is too small or diseased, through a small incision in the chest and then through the tip of the main pumping chamber of the heart. It does avoid the use of the heart lung machine and it is, in general, less from which to recover. So why isn’t everyone jumping on this bandwagon in a big way? What's holding up the show?

What's holding up the show is, in a word, safety. It is not a procedure for everyone. Conventional aortic valve replacement with surgery has a proven track record and a predictable rate of complications. TAVI/TAVR as yet does not. Data is emerging about this and some definable trends are developing.

One of the most recent articles in the surgical literature, from St. George's Hospital in London, supports the findings of some earlier cardiology trials, the PARTNER trials. In this British study patients thought to be at high risk for aortic valve replacement were all reviewed by a group of cardiologists and cardiac surgeons working together. They collectively determined who in their high risk group should receive surgery or undergo transcatheter replacement. The age of the patients ranged from 75 to 87 years old. Some of the patients considered were too sick for either procedure and were treated with medicine only.

Of those that had a procedure, either with conventional surgery or TVAI, no one died with the procedure or within the first 30 days afterwards. The TAVI patients tended to have a worse cardiac status before the procedure whereas the surgical patients tended to have more problems with other aspects of their health status.

The biggest and most statistically significant outcome differences were two. First, the TAVI patients had strokes 6.3% of the time compared to the surgical patients of whom 1.4% had a procedure related strokes. Second, fully 25% of the TAVI patients needed a pacemaker because of their procedure but none of the surgical patients did.

So what, if anything, can we conclude from this? To be clear, no definitive conclusions can be drawn because the clinical experience with TAVI continues to evolve and the technology used continues to evolve as well. What is becoming clear is that the risk of stroke with TAVI has consistently been demonstrated to be at least several times higher than with surgery. The need for a permanently implanted pacemaker is, to my way of thinking, astronomically higher.  You do appear to be trading an operative incision for a notably higher risk of serious complications. Only if the risk/benefit ratio of the procedure is appropriate is this rate of complication acceptable.

Having said this, there are folks who simply aren’t candidates for conventional aortic valve surgery. The approach the London based investigators used, where cardiac surgeons and cardiologists collaborate to reach a consensus for the best path of care for their high risk patients, is to be commended. TAVI as it stands is not for all patients. It simply is not safe enough. It is, however, for some. Defining who these individuals are is the hard part.

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