The second-generation CorPath GRX robotic system to assist percutaneous coronary intervention (PCI) proved to be safe and effective in the final results of the PRECISION GRX Registry, reported Thursday in a late-breaking session at the Society for Cardiovascular Angiography and Interventions (SCAI) 2021 Virtual Scientific Sessions.
Clinical success was achieved for 97.8% of subjects (955/ 976) and for 98.1% (1,204/1,227) of the robotically-treated lesions.
The device could help protect operators from unnecessary radiation exposure, Ehtisham Mahmud, MD, of the University of California, San Diego, and PRECISION GRX principal investigator, said during a press conference.
PCI has “been around for over 40 years, and stenting has been around for over 30 years,” he added. Despite improvements in interventional devices and pharmacotherapies, “actual techniques of PCI have remained unchanged.”
The robotic PCI technology in question – a second-generation iteration that for the first time allows control of the guide catheter – is already approved by the U.S. Food and Drug Administration (FDA). Its use has been “slowly increasing” over the last 5 years, he said, with a growing number of interventional labs across the U.S., Japan, the Middle East and other regions getting “comfortable” with these procedures.
PRECISION GRX is the first significant study to have “shown broadly by users of various experience” that the procedure can be safely utilized, Mahmud added.
The prospective international single-arm registry – sponsored by manufacturer of the device, Corindus Vascular Robotics – enrolled 980 subjects across 20 centers, mostly in the U.S. but also in Singapore and Brazil.
Subjects were the “usual mix” of patients treated for PCI, Mahmud said, with a median age of 65.4 ±11.6 years, majority male (73.5%) and a combined total of 1,233 lesions. Patients had obstructive coronary artery disease (>70% stenosis) with clinical indications for PCI treated with robotic PCI.
Acute coronary syndrome was present in 31.6%, while 68.8% had American College of Cardiology (ACC)/ American Heart Association (AHA) type B2/ C lesions, according to the study abstract. The lesion grades are “important to take into context” said Mahmud, noting that initial studies were mostly limited to type A and B1 lesions, rather than the broader PRECISION GRX cohort.
The clinical success co-primary endpoint was based on final Thrombolysis in Myocardial Infarction 3 flow, and less than 30% residual stenosis without an in-hospital major adverse cardiovascular event (MACE). The overall clinical success was seen across the board, with statistically no difference from ACC/AHA type A to C lesions.
A technical success co-primary endpoint, based on robotic clinical success without the need for unplanned manual assistance/conversion, was achieved in 86.5% (848/980) of the subjects and 89.2% (1,100/ 1,223) of robotically treated lesions.
Technical success – defined as clinical success plus the absence of manual assistance or conversion – was higher for type A/B1 lesions versus type B2/C lesions (94.5% vs. 85%; p < 0.001), the researchers added.
In terms of safety, Mahmud reported no in-hospital MACE, and 1.9% rate of residual stenosis of greater than 30%.
For those who did have to undergo manual assistance or conversion, there were, respectively, 44 and 45 cases (4.5% and 4.6%) of being unable to advance or cross the guidewire, balloon or stent catheter; five cases (0.5%) of inability to retrieve the guidewire, balloon or stent; 15 cases of robot malfunction (1.5%); and 32 (3.3%) marked as “others.”
“Individual subjects could have more than one of these reasons,” Mahmud clarified.
“Notably, a very small portion of cases was due to a malfunction or dysfunction of the robotic platform, and none of it resulted in an adverse event for a patient,” he added.
“The only lesions that were manually done were the chronic total occlusions; everything else was done robotically. The idea is that, if you think of a chronic total occlusion, once you have crossed it manually, there is still a lot of work that is often required.
“For individual operators, they can then be seated table-side, not getting radiated, and a large portion of the team does not need to be radiated as various device exchanged and the rest of the procedure are completed.”
In his presentation at SCAI, Mahmud stressed the importance of the technology as a way to protect interventionalists from radiation.
He showed occupational hazard figures for interventional cardiology, including cancer and orthopedic illness, stressing the risks are “significant” for operators working for 15 years or greater.
“Importantly, this changes how we do the procedure,” he said.
The operator can control the guide catheter – which was missing in the first iteration of the technology – as well as the guide wire and the stent or balloon delivery systems.
During the procedure, the interventionalist is seated behind a shielded cockpit without exposure to radiation and without the need to wear lead protection, “minimizing the orthopedic risk”, Mahmud said.
“These facts have been very important, and in previous studies, we have known that with robotic PCI, radiation … is reduced by 95% to the operator,” he added.
Asked about common concerns about delays in door-to-balloon time for ST-elevation myocardial infarction (STEMI) cases because of setting up the robotics, Mahmud replied: “Once you know a STEMI is coming … the whole system is set up ready to go in about 5 minutes.”
For centers already using robotic PCI, there “does not seem to be any price to pay at the patient level, meaning loss in door-to-balloon time,” he added.
Future development of the robotic PCI platform requires telecommunication for remote robotic PCI, as well as a focus on an over-the-wire platform for chronic total occlusions “that can be done completely robotically,” Mahmud said.
He added that the use of atherectomy and a second robotic drive for complex bifurcation lesions should also be developed in future.