More Complications Seen at Lower-Volume A-fib Ablation Centers

SAN FRANCISCO, CA—Patients treated at hospitals that perform 20 or fewer A-fib ablations each year are more likely to have complications, administrative data from the United States shows.

After adjustment, treatment at the lowest-volume centers was associated with greater risks of any complication, vascular complications, cardiac perforation, and stroke, Jim Cheung, MD (Weill Cornell Medicine, New York, NY), reported at the Heart Rhythm Society (HRS) 2019 Scientific Sessions here last week.

Early mortality—defined as death during the index admission or a readmission within the first 30 days—was higher at these hospitals as well.

Cheung was cautious when asked about what the response should be to these types of findings, pointing to a number of issues that introduce uncertainty. Operators may perform ablations at multiple hospitals, muddying interpretation of relationships with center-level procedural volume. Also, patients treated at the lower-volume centers tended to be older and sicker.

“I think the questions that one needs to ask are: do we need to establish centers of excellence or a minimal threshold of volume? Do we need to increase physician education about patient selection?” Cheung said to TCTMD, adding that there are also questions regarding the types of healthcare teams tasked with managing patients undergoing ablation at various centers. “I think these are all things that we need to look at.”

Importantly, he said, when stakeholders gather to examine these issues, it is critical for them to consider how to maintain good quality of care without harming patient access.

A word of caution also came from Dharam Kumbhani, MD (UT Southwestern Medical Center, Dallas, TX), who has studied volume-outcomes relationships in interventional cardiology for several years.

To TCTMD, he said many volume-outcomes analyses miss some key statistical features “and you come out with very erroneous conclusions,” adding that he’d need to see more details on the methodology used in this study to evaluate the statistical rigor.

That vetting is crucial for this type of research, Kumbhani added, because of the potentially far-reaching implications touching on reimbursement, accreditation, and guideline recommendations.

Most Ablations Done at Low-Volume Centers

Relationships between lower procedural volumes and poorer outcomes have been seen for other types of cardiovascular procedures, and the issue has become a particularly hot topic within the TAVR field. But it’s unknown whether such an association exists for A-fib ablation.

To find out, Cheung and colleagues turned to the US Nationwide Readmissions Database, examining 54,598 hospitalizations for A-fib ablation at 1,738 hospitals between 2010 and 2014. Hospitals were divided into tertiles based on annual procedural volume: 1-20, 21-52, and more than 52.

I think the questions that one needs to ask are: do we need to establish centers of excellence or a minimal threshold of volume? Do we need to increase physician education about patient selection? Jim Cheung

More than three-quarters of hospitals (79%) were in the lowest tertile, with 63% performing 10 or fewer ablations each year. Over time, the proportion of centers considered low-volume grew.

Before accounting for potential differences in case mix across hospitals, patients treated at the lowest-volume centers had the highest rates of mortality during the index admission, any complication, vascular complications, cardiac perforation, and stroke (P < 0.05 for all trends). They were also most likely to be readmitted within 30 days for any reason or for CV or non-CV causes.

But patients treated at low-volume centers tended to be older and sicker than those undergoing ablation at higher-volume centers, Cheung said.

After adjustment for those differences, some of the disparities related to procedural volume disappeared. However, patients treated at the lowest-volume centers—compared with the highest-volume hospitals—still had greater risks of the following outcomes:

• Any complication (OR 2.06; 95% CI 1.73-2.45)
• Cardiac perforation (OR 5.11; 95% CI 3.70-7.05)
• Vascular complications (OR 1.49; 95% CI 1.20-1.84)
• Stroke (OR 2.37; 95% CI 1.14-4.93)

Volume was no longer related to 30-day readmissions, although early mortality was more than twice as likely to occur at the lowest-volume centers (OR 2.24; 95% CI 1.09-4.61).

Learning From High-Volume Centers

Like Cheung and Kumbhani, HRS spokesperson Fred Kusumoto, MD (Mayo Clinic, Jacksonville, FL), treaded lightly when considering the clinical implications of these findings, telling TCTMD that it’s hard to know whether a minimum threshold for procedural volume should be implemented for A-fib ablation centers.

“There’s always unintended consequences, particularly if you then have continued volume requirements, where maybe someone might be incentivized to do a number of procedures to keep their numbers up or get their numbers up,” he said. “Having said that, though, clearly experience and monitoring how things go and your own results at your own center—or any center—are critical.”

And that’s true for hospitals of any size, Kusumoto added. “I think regardless of whether you’re a low-volume or a high-volume person looking at how you do your ablations . . . taking an honest appraisal of how you’re doing a procedure is critical.”

Kumbhani said trying to learn what high-volume centers are doing to provide better outcomes is more important than looking just at volume.

“Volume is a surrogate for a lot of other quality issues, so if you can actually phenotype what those issues are, then perhaps you could replicate those at the lower-volume hospitals rather than just saying it’s all driven by volume,” Kumbhani said. He added that when volume-outcomes relationships have been demonstrated in statistically rigorous studies for other procedures, they are typically not very strong.

Thus, he said, “If you can map out the things that the high-volume centers do better, then . . . from a resource utilization standpoint, I think that might go a longer way in being able to improve the care of these patients rather than just saying, ‘Go to a higher-volume center.’”