Doctoring General Cardiology

Possible clot issue on replacement aortic valves slows momentum of TAVR

The next frontier in cardiology is the replacement of cardiac valves via catheters rather than open-chest surgery. This new branch of cardiology is called “structural” cardiology. Trainees do entire “structural” fellowships in which they learn to do things with catheters that surgeons once did with open chest techniques.

You may have heard about TAVR–or transcatheter aortic valve replacement. This procedure was pioneered in Europe, and now more than 200,000 cases have been done worldwide. We have a nascent but successful TAVR program at my hospital.

In the US, TAVR is approved only for patients with high surgical risk. But that may change soon. After a 4-year experience, improved iterations of the valves, and emerging data on TAVR safety and efficacy, momentum is building to expand TAVR to lower-risk patients.

That momentum slowed this week. A small but compelling study (published in the New England Journal of Medicine) found that up to 40% of replacement aortic valves made from pig or cow tissue, did not open properly–possibly related to blood clots on the leaflets.

This was an unexpected and shocking finding. And it was made possible because of a novel imaging technique called 4-D CT scanning. Standard ultrasound (echo) did not have the resolution to see the problem.

The New England Journal of Medicine published two editorials along with the paper. Two experts in the field called the news “extremely important” while FDA representatives said the valves “remained safe and effective and that findings to date concerning reduced leaflet motion have not changed the overall favorable benefit–risk balance for these valves when they are used for their approved indications.”

This could be a big story. Medical dogma has long-held that tissue valves—because they are tissue and not metal—do not require anticoagulant therapy. This is the essence of their advantage over metal valves. Patients faced with valve replacement make the trade-off of less durability with tissue valves because they are told they won’t need warfarin. Add to that, tissue valves can now be placed via a catheter.

I covered these new findings in my column this week over at | Medscape Cardiology. The title and link are here:

Possible Clots on Bioprosthetic Aortic Valves: Potential Roadblock for Structural Cardiology


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