Radial PCI learning curve ranges from 30 to 50 cases in U.S.

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The learning curve for transradial PCI in the U.S. is “relatively shallow” and similar to that for operators outside the U.S., according to an analysis of CathPCI Registry data that was published online April 22 in Circulation.

Interventional cardiologists in the U.S. have been slow to embrace transradial PCI compared with many other countries. Although the practice has picked up momentum in the U.S., it still accounts for only 16 percent of PCI procedures.

Unlike other countries, U.S. fellows are less likely to be exposed to transradial PCI during training. Connie N. Hess, MD, MHS, of the Duke Clinical Research Institute in Durham, N.C., and colleagues speculated that technical challenges new operators face in learning the technique may be barriers to its adoption. They reasoned that defining the minimum threshold for obtaining proficiency might help spur its use.

Beyond addressing the learning curve issue, they sought to look at changes in patient selection, volume and procedural outcomes, and volume and in-hospital outcomes using data from the National Cardiovascular Data Registry CathPCI Registry. They focused on new transradial operators and used fluoroscopy time, contrast volume and procedure success as markers of proficiency.   

The final analysis included 54,561 transradial PCIs performed between 2009 and 2012 by 942 operators at 704 sites in the U.S. The median number of transradial PCIs performed was 40, with a median fluoroscopy time of 14.3 minutes, median contrast volume used of 180 mL per procedure and an overall success rate of 96 percent.

Over time, median fluoroscopy times and contrast use decreased with increased transradial volume and the success rate remained high. Operators selected more complex patients as transradial volume increased, including more women, more patients with New York Heart Association class IV heart failure, more patients presenting with STEMI and patients with higher bleeding risk.

They also took on more complex PCIs as they gained experience. Nonetheless, in-hospital mortality, vascular complications, access site bleeding, access site hematoma and observed bleeding events remained low and success rates high.

Based on the relationship between transradial volume and procedural outcomes, they placed the learning curve threshold for inexperienced operators in a range between 30 and 50 cases. The learning curve is on par with most estimates for operators outside the U.S.   

“These findings suggest that the learning curve for TRI [transradial PCI] is relatively shallow with the availability of modern interventional equipment and should inform TRI training guidelines in the U.S.,” Hess et al wrote. “Importantly, procedural metrics will likely continue to improve as an operator’s TRI experience increases.”

They added that the results were generalizable to most U.S. operators.