Circ: Researchers set minimum case volume for transradial PCI
A 5-F introducer sheath was inserted into the radial artery, and a guide wire and a 5-F Simon II catheter were introduced into the ascending aorta. Image source: Korean J Radiol 2006;7(1):7–13.
Transradial PCI has gained more attention recently as an intervention that can decrease vascular complications, promote early ambulation and shorten length of stay compared to the transfemoral approach. However, insufficient operator experience and training have limited the procedure's usage. A study in the August issue of Circulation: Cardiovascular Interventions has shown that procedural success depends on experience, and a case volume of 50 or more is required to achieve opportune outcomes.

“Despite the demonstrated benefits, TR-PCI [transradial PCI] has not gained widespread use by interventional cardiologists,” Warren T. Ball, MD, of the St. Michael’s Hospital and University of Toronto, and colleagues wrote. In fact, data coming from the National Cardiovascular Data Registry has shown that the intervention is being used for only 2 percent of procedures across U.S. hospitals.

Ball and colleagues speculated that one of the reasons for limited adoption of the procedure is inadequate operator training, which could potentially lead to lower procedural success rates. The greater contrast and radiation exposure may also hinder use.

During the current study, Ball and colleagues collected procedural characteristics for transradial PCI procedures that were performed between 1999 and 2008 to analyze the learning curve for these procedures and assess the relationship between procedural volume and benchmarks of success. A total of 1,672 patients underwent transradial PCI by 28 operators.

Of the 1,672 patients, the mean age was 62 years, 81 percent were men and stable angina was the indication for PCI in 55 percent of patients.

Ball and colleagues stratified transradial procedures into case volume tiers: one to 50 (655 patients), 51 to 100 (344 patients), 101 to 150 (213 patients) and 151 to 300 (141 patients). The control group was considered to be 300 cases or more. The researchers compared failure rates, contrast usage and fluoroscopy time.

The researchers found that procedural failure, which was 4 percent in the overall cohort, was highest within the group that performed one to 50 procedural cases compared to those who performed 51 to 100 cases and the control group. Contrast was also used more often in the operator group who performed one to 50 procedures (180 mL) compared to the 151 to 300 group (157 mL) and the control group (168 mL). The fluoroscopy times were also higher in those performing between one and 50 cases compared to those who performed between 101 and 150 procedures, 15 minutes vs. 13 minutes.

Findings on failure of the procedure showed that 38 percent of patients experienced spasm, 16 percent subclavian tortuousity, 16 percent poor guide support, 10 percent failed access and 7 percent a radial loop.

The researchers concluded that the odds of procedural failure were reduced by 32 percent for each 50 increments in case volume. “The main findings are that the TR-PCI learning curve is steep, with no significant difference in failure rate after 50 TR-PCI cases compared to that of experienced operators,” the authors wrote.

The authors said the current findings have important implications for clinical practice including the fact that the identification of a minimum volume could be a guide for transfemoral operators to incorporate transradial PCI into practice. Secondly, the results pinpoint that an interventional cardiology training program could help ensure the minimum number of transradial PCI procedures.

“Contrary to common practice of using TR-PCI when TF-PCI is not feasible, appropriate patient selection during the learning curve can improve outcomes in all patients, including those at high risk of bleeding and vascular complications,” the authors concluded.

“The present findings have implications both for PCI operators looking to expand their skills and for defining standards for training.”