Radial Rivals Femoral Access for Invasive ACS Treatment

April 04, 2011

April 5, 2011 (New Orleans, Louisiana) — A head-to-head comparison of radial vs femoral access for the treatment of patients with acute coronary syndromes (ACS) has shown that treatment via the radial artery did not reduce the rate of death, MI, stroke, or non–coronary artery bypass graft (CABG)-related major bleeding at 30 days [1]. Transradial access, however, did result in a 63% reduction in the risk of large vascular-access complications.

Presenting the results of the Radial vs Femoral Access for Coronary Intervention (RIVAL) trial during the late-breaking clinical-trials session here at the American College of Cardiology 2011 Scientific Sessions, the investigators did observe a benefit of the radial approach in patients with ST-segment-elevation MI (STEMI), as well as in centers that perform a high volume of procedures via the radial artery.

Lead investigator Dr Sanjit Jolly (McMaster University, Hamilton, ON) said the RIVAL trial tested a paradigm-shifting hypothesis--that radial access would lower the rate of death, MI, stroke, or non–coronary artery bypass graft (CABG)-related major bleeding at 30 days--and that even though the results failed to show a benefit, the procedural success rates were equivalent between the two approaches, and the vast majority of patients said they would prefer the radial approach if they needed to undergo a repeat procedure.

"Interventional cardiologists should feel reassured that both radial and femoral procedures are safe and effective in the current era," Jolly told heartwire . "The second take-home point is that experience and expertise does matter, and the more procedures you do the better you get. Clinicians and patients may decide, with similar PCI efficacy, to use radial access because of the lower rates of vascular complications."

In an editorial accompanying the April 4, 2011 online publication of RIVAL in the Lancet [2], Drs Carlo Di Mario and Nicola Viceconte (Royal Brompton Hospital, London, UK) call radial access a worthy rival for transfemoral PCI but say that it is not a clear winner. That said, "there is little justification to ignore one of the main developments in interventional cardiology and stubbornly refuse to embrace a technique likely to reduce minor adverse events (but in patients with STEMI, possibly also major adverse events and mortality) and improve patients' comfort," they write. They add the operators with a high workload of acute procedures should consider retraining in transradial PCI, and all new interventionalists should be taught the transradial approach.

"Conversely, it is important not to demonize the femoral approach, which is more suitable when large guiding catheters are required and prolonged procedural time is expected for complex lesions, such as chronic total occlusions, some large bifurcations, and diffuse or very calcified lesions," write Di Mario and Viceconte.

The RIVAL Trial

The RIVAL trial included 7021 patients from 158 hospitals in 32 countries, making it the largest comparison of the transradial and transfemoral approaches. Just under half of patients were enrolled from the CURRENT-OASIS 7 trial into RIVAL, with an additional 3190 patients enrolled after that trial was completed. Patients included in the trial had ACS with and without ST-segment elevation, and an invasive treatment option was planned by an interventional cardiologist who had performed a minimum of 50 radial procedures for coronary angiography or interventions in the last year.

At 30 days, the primary outcome--a composite of death, MI, stroke, or non-CABG-related major bleeding--occurred in 3.7% of patients randomized to radial access and in 4.0% of patients assigned to the femoral approach, a nonsignificant difference. In terms of secondary end points, including death, MI, or stroke, there was also no significant difference between the two approaches. In addition, there was no significant difference in non–CABG major bleeding at 30 days, although a post hoc exploratory analysis that used a definition of bleeding from the ACUITY trial revealed a higher rate of major bleeding among patients treated via the femoral artery.

During the press conference announcing the results, Jolly said that the components of the ACUITY definition include large access-site hematomas, which is a vascular-site complication. As a result, the ACUITY definition was likely more sensitive to the radial intervention. As noted, there was a significant difference in the rate of major vascular complications, with a reported event rate of 1.4% among those treated with radial access and 3.7% among those treated with the femoral approach.

Commenting on the bleeding end point, Dr Gregg Stone (Columbia University, New York), the lead investigator of the ACUITY trial, said that large bleeding, such as gastrointestinal, genitourinary, and intracranial, has a significant impact on subsequent mortality, but small, localized bleeding, including access-site hematomas, is not associated with a subsequent increased risk of death. In RIVAL, two-thirds of bleeds were not at the access site.

Speaking with the media, Dr Edward McNulty (University of California, San Francisco), who was not involved in the RIVAL trial, noted that while access-site hematomas do not affect mortality, they do affect patient satisfaction. "I think one of the take-home messages from the RIVAL trial is that while there might some resistance on the doctor side to adopting this approach, the patients certainly like it, and I think that will drive adoption."

Investigators also observed a statistically significant 40% relative reduction in the risk of death, MI, stroke, or non-CABG-related major bleeding and a significant 61% relative reduction in the risk of death among STEMI patients treated via the radial artery. They also reported a significant reduction in the risk of the primary outcome, a 51% reduction, among PCI centers that performed the highest volume of radial procedures.

Asked why there was a benefit among the STEMI cohort, Jolly said that more experienced operators tackled these patients using the radial artery, mainly because these were the interventionalists most comfortable using the radial approach. Also, STEMI patients tended to be treated more aggressively with potent antithrombotic therapies, and this might have led to a downstream benefit.

In terms of operator experience, Jolly said that the learning curve associated with radial-access interventions is still unknown, but operators who performed more than 140 cases annually via the radial artery were considered the most experienced in RIVAL (>140 cases per year placed them in the highest tertile of operator experience). This translates into roughly three radial cases per week, he noted.

Adoption of the Radial Approach

In current US practice, based on 2010 data from the National Cardiovascular Device Registry (NCDR), just 4.2% of stent procedures are performed via the radial artery, although this number is expected to increase. McNulty said he performs approximately 10% of his procedures transradially, and Jolly does about 80% of his procedures via the radial artery. Stone, on the other hand, performs 99% of all of his cases through the femoral artery, pointing out that he also uses bivalirudin (Angiomax, the Medicines Company) in all his cases, and this reduces bleeding approximately 40% to 50%. In addition, his group uses vascular closure of devices in the vast majority of patients, which allows them to get walking quicker. Still, at Columbia Medical Center, now more than 20% of cases are performed via the radial route.

"I think the RIVAL trial is consistent with most people's practices and experiences, and I don't think the data in and of itself will change practice," said Stone. "What might change practice is patient preference, comfort, those sorts of issues, which I think, in the way we do it, is sort of minimized."

Also commenting on the RIVAL trial, Dr Martin Leon (Columbia University) said that radial-access interventions are limited somewhat by sheath sizes--in RIVAL, 77% of patients were treated using 6-F sheath sizes--but in complex cases, such as those with bifurcation lesions, larger sheath sizes are needed, and this precludes the global adoption of the radial approach.

"I think you have to be selective, and I think there will be some operator preference, but I do agree, there is going to be an increase in radial cases in the United States," said Leon. "There will be patient preference, and a lot of the young operators wanting to get more experience, and these data certainly show that it's no worse, and there might be some advantages in some patient subsets."

Sanofi-Aventis, the Population Health Research Institute, and the Canadian Institutes of Health Research sponsored the RIVAL trial.

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