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Hospitals maintaining their aortic valve surgical expertise had the best track record for patient survival after transcatheter aortic valve replacement (TAVR), according to an observational study.

Centers performing the most surgical aortic valve replacements (SAVRs), averaging 97 cases or more per year, were quicker to adopt TAVR after FDA approval in 2011 and grew their TAVR volumes faster than did hospitals with low SAVR volume, found Art Sedrakyan, MD, PhD, of Weill Cornell Medical College in New York City, and colleagues.

High SAVR volume alone did not independently predict better TAVR patient outcomes at a given hospital. However, lower 30-day mortality after TAVR was seen with high TAVR volume, which was defined as above the median (35 in the first year, 52 in the second, 84 in the third, and 137 in the fourth).

Centers with high volume of both procedures had the lowest death rates after the transcatheter procedure (OR 0.77, 95% CI 0.66-0.89), Sedrakyan's group reported online in .

The study's findings have important policy implications, they said, given the Medicare National Coverage Determination for TAVR in the works.

"Our study demonstrated that assessing hospital SAVR volume alone is not adequate and potentially misleading given the tendency for these hospitals to accumulate TAVR volume more quickly. It was within hospitals with high SAVR volume that the association of accumulated TAVR volume with better outcomes became very strong."

Better 30-day outcomes associated with high SAVR volume on the institutional level did not translate into better 1- or 2-year TAVR survival.

Experience certainly still counts, wrote Colin Barker, MD, and Michael Reardon, MD, both of Houston Methodist Hospital, in an accompanying editorial. "How much is needed may remain in question, but it appears from these data that surgeon volume is not associated with TAVR outcomes."

"Procedural survival may be associated with experience, but longer-term survival is associated with how well the procedure corrects the problem and the intrinsic risk of the patient treated. If similar procedural success is achieved, then the difference is more likely associated with high-volume centers selecting better-risk patients," they said.

The study relied on Medicare claims data and included 438 hospitals performing TAVR procedures (n=60,538) from 2011 through 2015. The number of TAVR centers rose from 113 in 2011 to 415 in 2015. The sites reported a median of 83 procedures annually.

Hospitals with low or high SAVR volumes after initiating TAVR programs had these case volumes stay stable over the years, according to Sedrakyan and colleagues.

This finding contrasted with another recent study showing that institutions with the highest TAVR volumes performed fewer surgical procedures year over year from 2011 to 2014. Overall, the SAVR volume did not fall in the U.S., however, due to other hospitals continuing to pick up surgical cases.

Sedrakyan's group noted that hospitals with high TAVR and SAVR volumes tended to take patients with the greatest burden of comorbidity.

Residual confounding was a possible limitation of the study, they cautioned, especially since the Medicare claims data they used did not include detailed clinical information. Moreover, their dataset provided an incomplete picture of all TAVRs in the U.S. and failed to include anything after 2015.

"Surgical aortic valve replacement may not have changed much since 2015, but TAVR is almost a new animal and still changing rapidly. Let's hope the authors repeat this crucial analysis with newer data soon," Barker and Reardon wrote.

As to the best way to increase access to TAVR while maintaining or improving outcomes, the editorialists said they doubted that volume requirements will always be around, "because nothing else we do is restricted by volume at a federal level, because this is generally a hospital credentialing issue."

Instead, they said it's time for the TAVR field to go from outcome transparency with the Transcatheter Valve Therapy registry to "the next step of data transparency for programs and operators."

"If this can be done in an educational, quality-improvement spirit rather than being used as a punitive club, we believe that TAVR may well be one of the most successful procedures ever introduced to medicine," according to Barker and Reardon.