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Angioplasty and Stenting from the Wrist Safe and Effective: The RIVAL Trial
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transradial procedure
April 8, 2011 -- The first large-scale trial comparing angioplasty performed via the wrist (transradial) with the procedure done from the leg (femoral) was presented at this week's annual meeting of the American College of Cardiology. Dubbed "RIVAL" (RadIal Vs. FemorAL Access for Coronary Intervention Study) the trial enrolled 7,021 patients from 158 hospitals in 32 countries. These were patients with Acute Coronary Syndrome (ACS) who were experiencing unstable angina or a heart attack (either NSTEMI or STEMI) -- and who were going to be treated with angioplasty and/or stents

The question for the RIVAL study: Is radial access superior to femoral?

Although radial is used more than half the time in many countries around the world, only 5-7% of cases in the United States are done this way, even though cardiologists who perform diagnostic catheterizations, angioplasty and stenting from the radial approach report much lower bleeding complications, much increased patient comfort and quicker recovery.

So the results of RIVAL were much anticipated by the U.S. cardiologists gathered this week in New Orleans. In fact, Dr. Ralph Brindis, president of the American College of Cardiology, stated before the meeting that the adoption of transradial access may be "at a tipping point".

The RIVAL study looked at patient outcomes 30 days after the procedure; the primary endpoint to be measured was a composite of death, heart attack, stroke or non-CABG major bleeding. Although a number of previous studies have shown that the transradial approach virtually eliminates access-site bleeding complications, the results of RIVAL did not prove superiority of either the wrist or leg approach. There was no statistically significant difference in the composite: about 4 out of 100 patients suffered one or more events, whether they were in the radial or femoral group (3.7% in the radial group and 4.0% in the femoral).

Although there was no "winner", in fact both approaches were winners, in that the events were low in frequency. Furthermore the wrist approach has now been shown to be as safe and effective as the much more widely-utilized leg/groin access site, countering any remaining arguments against its widespread use.

Increased Vascular Complications with Femoral Approach
However, there was a big difference in major vascular complications, an "additional secondary endpoint" defined as: pseudoaneurysms needing closure, large hematoma (as judged by investigator), arteriovenous fistula, or an ischemic limb needing surgery. And, while these were not part of the primary endpoint composite, such complications are not small problems; they affect the patient, length of stay and recovery, and they most definitely increase hospitalization costs. In the transradial group, major vascular complications were 1.4%, while in the femoral they were more than 2 1/2 times greater at 3.7%. A major vascular complication needing surgical repair can be a very expensive complication, and a debilitating one for the patient.

Two of the most posted to topics on Angioplasty.Org's Patient Forum have to do with complications from femoral catheter-based procedures and femoral vascular closure devices. Over 1,300 posts delineate the various types of problems encountered in the real world by patients: from minor bruising and soreness to vascular injury requiring surgery or persistent nerve trauma which permanently has limited running, bicycling, even walking -- even a few stories of retroperitoneal hemorrhages, not discovered in-hospital (as they often are not), which resulted in death. To be sure, these femoral complications are still small in percentage, but can be devastating to patients.

Advantage for Transradial Seen in STEMI Patients
Other differences were also seen, for example, in patients who were treated for the most serious type of heart attack: an ST Elevated Myocardial Infarction (STEMI). Here the primary endpoint showed a lower event rate for the radial technique vs. the femoral (3.1% vs 5.2%). One reason may be that STEMI patients are given much higher doses of antithrombotic drugs during the procedure to keep their blood from clotting, thus raising the risk for bleeding complications at the access site. Radial showed a clear advantage for STEMI patients.

Low Event Rates and Selection of Operators May Have Affected Results
As has been the case in several recent interventional cardiology trials, unexpectedly low event rates overall may have muddled the comparisons. Even though the investigators increased the sample size from 4,000 to 7,000 in 2009, when it became clear that event rates were lower than originally planned for, they wrote:

"RIVAL was underpowered to conclusively rule out moderate but important differences in the primary outcome. On the basis of the reported event rate of 4%, a sample of size of 17,000 patients would be needed to have 80% power to detect a 20% relative risk reduction in the primary outcome."

Another concern expressed by some was that the bar for radial operators was too low -- those chosen to take part in RIVAL had to have done at least 50 radial procedures in the previous year, considered by most "radialists" to be a very low volume. Most experienced radial operators feel that just to get past the initial learning curve takes about 100 cases. A cardiologist who practices "Radial First" uses the radial approach as the default for all cases and therefore would normally have a much higher annual volume. As expected, the study showed better outcomes at centers with high radial case volume. Perhaps, if only the most experienced radial operators were measured against the most experienced femoral operators, the outcomes might have favored radial even more.

Even though the final conclusion of the RIVAL study did not show superiority of one approach, the RIVAL investigators, led by Dr. Sanjit Jolly of McMaster University's Population Health Research Institute in Hamilton, Ontario, concluded that:

Dr. Sanjit Jolly
Dr. Sanjit Jolly

"Radial and femoral approaches are both safe and effective for PCI.... In patients with ACS undergoing coronary angiography, radial access did not reduce the primary outcome of death, myocardial infarction, stroke, or non-CABG-related major bleeding compared with femoral access.

"However, radial access significantly reduced vascular access complications compared with femoral access, with similar PCI success rates, and was more commonly preferred by patients for subsequent procedures."

So the question remains whether the RIVAL trial results will push the adoption of transradial access past Dr. Brindis' "tipping point." There has been a groundswell of interest in the transradial approach over the past couple of years and every major interventional meeting now hosts a transradial training component. Other organizations, companies and most recently, the Society for Cardiovascular Angiography and Interventions (SCAI), also have started scheduling one or two day training courses in radial access. SCAI, in fact, issued a statement on the outcomes of the RIVAL Trial earlier this week. Still, moving the entire subspecialty of interventional cardiology from 5% to a "tipping point" will take commitment on the part of cardiologists who want to learn this technique, and will most likely be driven by patient preference.

The RIVAL study was published online in The Lancet, simultaneously with its presentation at the ACC meeting.

About The Radial Access Center on Angioplasty.Org
To assist in educating the professional and patient population in the U.S. about the this technique, Angioplasty.Org created the "Radial Access Center for Transradial Approach" in 2007, a special section devoted to information and news about the transradial technique, for both patients and physicians. The Radial Center features interviews with leading practitioners of the radial technique, such as Drs. Jeffrey Popma, Sunil Rao, Mauricio Cohen, John Coppola, Shigeru Saito and Jennifer Tremmel.

For interventional cardiologists and cath lab staff, Angioplasty.Org also maintains a listing of upcoming training courses in the transradial approach. For patients, there is a unique "Radial Hospital Locator" that lists U.S. centers practicing radial angiography. As Dr. Howard Cohen of Lenox Hill Hospital in New York says of the wrist technique, "Patients really prefer it. 95% of people who've had it both ways would say 'I'm coming back to you, Dr. Cohen because I like this transradial a lot better than the other way!'

Reported by Burt Cohen, April 8, 2011