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There is cause to be concerned about transcatheter aortic valve replacement (TAVR) moving to younger patients, and clinicians offered several reasons why.

For one, bioprosthetic valves have been associated with a larger risk of reoperation for younger patients after surgical aortic valve replacement when compared with mechanical alternatives, , of Weill Cornell Medicine and New York-Presbyterian Hospital, and colleagues noted in .

"Bioprosthetic valves do not last as long as mechanical valves primarily because the valve leaflet tissue degenerates," they wrote. "Although it might eventually be shown that the valves used in TAVR outlast the bioprosthetic valves implanted at surgery, this is a matter of conjecture and an untested possibility."

Also, young individuals are more likely to have bicuspid aortic stenosis -- and its accompanying risk of incomplete valve expansion and heart block. Subclinical clinical leaflet thrombosis in TAVR valves is yet another important risk, according to Sedrakyan's group.

"Before the use of TAVR further increases in patients with lower surgical risk, long-term evidence is needed from randomized clinical trials using a mechanical valve comparator arm to TAVR with a minimum 5 years of follow-up," the authors urged. "Such studies should also assess the cost-effectiveness of TAVR."

And although a degenerated bioprosthetic valve can be resolved with a valve-in-valve procedure, they pointed out, "a repeat TAVR placement ... is still an additional invasive and costly procedure, with risks of morbidity and mortality."

"Although TAVR is an important new technology that has improved the lives of many patients and spared them from the risks and life disruptions of open-heart surgery, the jury is still out on its role in younger patients, who are the main group of patients with lower surgical risk," Sedrakyan and colleagues concluded.

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