A new Mayo Clinic study suggests that it may take as many as 30 procedures for a physician to become proficient at transcatheter aortic valve implantation, rekindling the debate over what credentials docs ought to have to perform the procedure.

Surgeons reported significant improvement in technique between their 1st and 44th TAVI procedures, with most rapid improvement occurring up to the 30th procedure, according to a study published in the December issue of the Journal of the American College of Cardiology: Cardiovascular Interventions.

The study again raised the specter of a credential system for physicians and hospitals performing TAVI procedures, with journal editor Dr. Peter Block advising interested parties to keep their eyes open for legislation over the next year.

Data from the Partner trials showed that physicians, on average, reduced procedure times from 12 minutes to 7 minutes by the third trimester of the trial; patients were exposed to lower volumes of contrast and radiation as their cardiologists got more experience with the procedure. The reductions ultimately made procedures safer, but didn’t effect overall outcomes for complication rates, hospital stays or mortality, TheHeart.org reported.

Data from the Partner trial’s B arm, made up of patients considered "inoperable" or unfit for open-heart surgery, helped support FDA clearance for Edwards Lifesciences Corp.’s (NYSE:EW) Sapien valve. That implant is the first and only catheter-based aortic valve on the U.S. market, two years ahead of its nearest competitor, Medtronic’s (NYSE:MDT) CoreValve.

With a device now available, many cardiology centers are going to want a piece of the action, Block wrote in an editorial accompanying the study.

"How all this will play out over the next year should concern every center and operator contemplating the addition of TAVI to their list of available therapies," he wrote. "[I]t may take more than a full year for an operator to become procedure ‘proficient,’ [and] the question of maintenance of proficiency is totally unanswered at present."

There will be about 100 U.S. sites performing about 100 TAVI operations annually in the coming years, according to Block, meaning some sites will perform fewer than 1 procedure per week, assuming rumored estimates of 25,000 to 30,000 procedures per year pan out.

The FDA and the American College of Cardiology have voiced support for licensing procedures as well as for a limit on how many U.S. sites have certification to perform TAVIs, Block noted, adding that he expects the watchdog agency to add additional restrictions to the availability of the procedure by narrowly defining "inoperable."

"TAVI may well be a center-stage diva, but it is also a jealous, high-maintenance mistress," Block concluded. "It should be an interesting rollout."