The authors of a new study suggested CMS revise its standards for left ventricular assist device (LVAD) implantation based on patients from the lowest-volume centers demonstrating worse 90-day survival outcomes.

When compared to medium-volume centers, those performing 10 or fewer procedures per year were associated with a 35 percent risk-adjusted increase in mortality. Meanwhile, high-volume centers (more than 50 implants annually) showed a 17 percent increased risk of mortality versus medium-volume centers (31 to 50 implants per year) in the study of 7,416 patients.

CMS requires a minimum of 10 LVADs or total artificial hearts over a three-year period.

“It begs the question whether stricter center volume minimums are necessary for ensuring good patient outcomes after LVAD,” wrote lead researcher Jennifer A. Cowger, MD, from the Henry Ford Medical Center in Detroit, and colleagues in JACC: Heart Failure.

The researchers said referral bias may have played a role in the lower survival rates for high-volume centers. Patients at these centers were often sicker and may have already been declined for surgery at lower-volume centers. High patient volume may have also negatively impacted outpatient care, Cowger et al. noted.

While the authors attempted to adjust for patient risk, they acknowledged it’s an inexact science. Another limitation of the study was it failed to account for individual surgeon experience. Many LVAD centers could have multiple surgeons, especially high-volume ones, the authors pointed out.

In an accompanying editorial, a pair of Cleveland Clinic doctors said centers performing 31 to 50 procedures per year could be in a “sweet spot” for best outcomes.

“Most centers this size offer both heart transplantation and LVAD therapy and have multiple heart failure cardiac surgeons and cardiologists,” wrote Randall C. Starling, MD, and Andrew Xanthopoulos, MD. “Patients likely will receive the best therapy option versus the only option the center has to offer. … The medium-volume center is likely to be well staffed but not over stressed due to an overwhelming patient volume.”

However, the editorial authors disputed the study researchers’ suggestion that standards be revised based on LVAD volume.

“Access to care is important, and limiting centers purely based on a volume threshold would be unjust,” Starling and Xanthopoulos wrote. “A low-volume center with experienced personnel and careful judgment might achieve excellent results. We believe a volume threshold should serve as a guide, but that demonstrated excellent outcomes should trump a volume threshold.”