Domo Arigato: High Success Rates, Low Radiation With Both Radial and Femoral Robotic PCI

NEW ORLEANS, LA—High rates of technical and clinical success can be achieved with robotic PCI performed via transfemoral or transradial access, according to final results from the multicenter PRECISION registry. Procedure times and patient radiation exposures were similar regardless of access type.

Operators are the ones most likely to benefit from performing PCI in this manner, said the study’s lead author Ehtisham Mahmud, MD (University of California, San Diego School of Medicine). “You essentially eliminate radiation exposure to the primary operator,” he noted in a press conference prior to his presentation at the Society for Cardiovascular Angiography and Interventions (SCAI) 2017 Scientific Sessions here.

Speaking futuristically, he added that it is possible that large healthcare systems could have an experienced operator on site robotically assisting less experienced operators at other sites. “I think we’re still in the early stages, but adoption and utilization is increasing,” Mahmud said.

Possible Advantage for Radial Over Femoral

Sixteen centers in the United States participated in the PRECISION registry, which collected clinical and procedural data on the CorPath 200 System (Corindus), a US Food and Drug Administration-approved robotic technology that enables remote control of coronary guidewires and stents from an operator cockpit.

For the all-comers inclusion registry, 754 robotic PCI procedures involving 949 lesions were treated between September 2013 and March 2017. Of these, 452 procedures were performed via radial and 298 via femoral access, with access chosen at the discretion of the operator.

For the purposes of the study, the PRECISION researchers defined clinical success as final residual stenosis < 30%, TIMI 3 flow, and no MACE. Technical success, which was not prespecified, was defined as clinical success with no unplanned manual assistance.

Although overall results from the analysis showed better technical success rates for radial versus femoral robotic procedures (88.6% vs 82.4%; P = 0.017), with the same being seen for clinical success (98.9% vs 94.9; P = 0.0012), Mahmud urged caution in the interpretation of these findings because of mismatch in the baseline characteristics between the two groups, including older age, more complicated lesions, and more calcification in the femoral group. However, type B2 and C lesions accounted for roughly two-thirds of all cases in each group; this is important, Mahmud noted, since previous studies of robotic PCI have largely excluded such patients.

PCI time was longer by 8 minutes in the femoral group, but patient radiation exposure as expressed by dose area product for contrast volume used was similar in the femoral and radial groups (169.4 mL vs 179.2 mL; P = 0.98).

In propensity matching, procedural characteristics and all clinical outcomes were comparable between the radial and femoral approaches with the exception of a slight advantage of clinical success remaining in the radial group, driven primarily by the higher MACE rate in the femoral group (2.9% vs 0; P = 0.03). Of six MACE that occurred, all were in the femoral group.

Mahmud said at the moment about 40 centers in the US are using this robotic system, adding that he believes those numbers will increase.

Selection Bias and Learning Curves

Session moderator Robert Applegate, MD (Wake Forest University School of Medicine, Winston-Salem, NC), expressed some surprise that the radial group appeared to have a higher rate of technical success.

“I don’t know why [but] in my mind I probably thought you would have had to readjust the guide more often . . . which has been my experience,” he observed.

Mahmud agreed that it was an unusual finding, but said he believes that operators probably were choosing less complicated cases for their radial robotic procedures.

“It’s hard to correct for that selection bias,” he noted. “Secondly . . . as most of us have gotten more and more comfortable with the robotic PCI we have learned with the first-generation system that you have to kind of use slightly more aggressive guide catheters than you would otherwise, so that is another possibility—that people knew they were going with the robotic system and might have chosen a different guiding catheter.”

As to the learning curve, Mahmud said some studies have shown that 25 cases is the threshold for procedure time to start decreasing, plateauing around 50. He added that more research is needed to see if those numbers hold up across multiple sites and operators.