SAVR volumes alone not predictive of TAVR outcomes—but combined experience is

Hospitals offering transcatheter aortic valve replacement (TAVR) tend to produce the best survival outcomes when both TAVR and surgical AVR (SAVR) caseloads remain high, according to a study published Oct. 31 in JAMA Cardiology.

The analysis included more than 60,000 TAVR procedures performed in Medicare beneficiaries at 438 hospitals from October 2011 through December 2015. It found that centers that performed the most SAVRs, averaging more than 97 per year, were more likely to be early adopters of TAVR and grow their TAVR volumes quicker than hospitals performing fewer SAVRs.

When SAVR volume was analyzed individually, it wasn’t significantly associated with TAVR mortality outcomes at 30 days, one year or two years. TAVR caseload was more important, but outcomes further improved when that experience was supplemented by surgical expertise.

Specifically, when a center had high volumes of both procedures, the odds of 30-day mortality after TAVR were 23 percent lower than in centers with low volumes of both procedures. Centers with high TAVR but low SAVR volumes demonstrated a 15 percent risk reduction compared to those with low volumes of each intervention.

“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,” wrote lead author Jialin Mao, MD, MSc, with Weill Cornell Medical College in New York, and colleagues. “It was within hospitals with high SAVR volume that the association of accumulated TAVR volume with better outcomes became very strong.”

The relationship between TAVR and SAVR volumes and TAVR outcomes is a hot topic right now because CMS is set to release a new National Coverage Determination (NCD) for TAVR next June. The NCD could update how many procedures centers must perform annually to be reimbursed for TAVR in Medicare patients.

A consensus document authored by several cardiology societies proposed a threshold of 50 TAVRs and 30 SAVRs per year for a center to maintain a TAVR program. But a researcher at TCT.18 pointed out 43 percent of TAVR sites in 2016 wouldn’t have reached those minimum requirements, raising questions about whether increasing those targets would restrict access to treatment.

Mao et al. said there are several potential explanations for why centers with the highest combined SAVR/TAVR caseloads produced the best survival outcomes.

“The joint effect of hospital SAVR and TAVR volumes indicated that better outcomes are achieved when frequent use of TAVR is combined with surgical expertise,” they wrote. “In addition, these hospitals with high SAVR and TAVR volume are often hospitals involved in early clinical trials and are more likely to have access to newer technologies, contributing to improved outcomes.

“The lower 1-year and 2-year mortality of patients treated at hospitals with high SAVR and TAVR volume suggests that these hospitals may also have made better candidate selection and offered better continuing care after discharge.”

The authors suggested policymakers consider their findings when establishing minimum volume requirements, and take into account “the combined benefit of hospitals’ surgical and accumulated TAVR experience for patients undergoing TAVR.”

A notable limitation of the study was its lack of data past 2015, especially considering TAVR is a rapidly changing area of research and clinical practice.

“It appears from these data that surgeon volume is not associated with TAVR outcomes,” Colin M. Barker and Michael J. Reardon, MD, with Houston Methodist Hospital, wrote in a related editorial. “Would anyone be surprised if we suggested interventional cardiologist experience with TAVR is not associated with SAVR outcome? We think not.

“We both play in the same orchestra. The fact that one person plays the violin well and another plays the cello well may help them both understand stringed instruments, but it is not a good measure of how well either of them will play the guitar on their early attempts.”

The editorialists predicted volume requirements will eventually go away for TAVR because other interventions aren’t restricted by volume at the federal level and “this is generally a hospital credentialing issue.”

Instead, they touted the opportunity to have transparent outcomes data available to programs and operators, which could help guide practice.

“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,” Barker and Reardon wrote.