The standing-room-only crowd of physicians that packed a meeting room at the recent Transcatheter Cardiovascular Therapeutics conference in San Francisco to hear presentations on transradial percutaneous coronary interventions suggests interest in the technique is growing in the U.S.

However, as Jeffrey Popma, M.D., Harvard Medical School, pointed out in a Sept. 23 talk at TCT, advocates for the technique are having a hard time convincing their colleagues to adopt the transradial approach, despite a growing body of evidence showing it is safer than the more common transfemoral approach.

Only about 1% of percutaneous coronary interventions in the U.S. are done with the transradial approach, compared to as many as 40% in parts of Europe and Japan, according to the ¹ Transradial Access Center Web site sponsored by Japanese medical-device conglomerate Terumo.

Terumo's Interventional Systems division markets guidewires, catheters, introducer sheaths, guiding sheaths and embolization products for interventional procedures. The company, in concert with Frederick, Md.-based advocacy group Patient Medical Association, is currently supporting an education effort to increase adoption of the transradial approach.

Fewer Complications From Access-Site Bleeding

With the transradial approach, the interventionalist pushes a catheter through a small incision in the patient's wrist and threads the catheter to the heart through the artery in the arm. In the transfemoral approach, the incision is near the patient's groin.

"The bleeding complications associated with the femoral approach are underappreciated, or maybe the other way to say it is that the benefits from the radial artery approach aren't recognized," Popma said.

A 2008 retrospective study of 593,094 patients in the National Cardiovascular Data Registry by Sunil Rao, M.D., Duke Clinical Research Center, found that transradial and transfemoral PCI had roughly the same rate of procedural success, but that patients treated with the transradial approach were less than half as likely to have a bleeding complication. The benefits of the transradial approach were more pronounced in patients over 75, Rao, et al., found.

The risk of bleeding complications in the access site is especially difficult to manage in patients with drug-eluting stents who have to take anti-clotting drugs to reduce the risk of stent thrombosis.

Despite the lower risk, transradial procedures remain only a small portion of U.S. interventions because of cultural, financial and logistical barriers, Popma said.

Several studies have shown that patients treated with a transradial percutaneous coronary intervention are more likely than femoral patients to be able leave the hospital on the same day as the procedure. CMS considers these patients to be outpatients, and the outpatient codes for stenting pay about half as much as the comparable inpatient procedures, creating a disincentive for interventionalists to learn the new procedure, Popma pointed out.

Popma also pointed out that studies show a significant learning curve associated with the transradial technique. Interventionalists can generally master the technique in around 100 cases, the studies show, but many physicians are deterred by the learning curve, and few interventionalists learn the technique during their specialty training in coronary interventions.

"There's been a psychological barrier - we can use these catheters in the arm and they work very well ... but the individual interventionalist has to decide that this is something that I'm going to do and not get discouraged in the first 25 cases," Tift Mann, M.D., Wake Heart Associates, Raleigh, N.C., said.

Despite the barriers, all the participants at the TCT sessions on transradial interventions encouraged U.S. physicians to learn and adopt the transradial approach for more of their patients.

- Reed Miller ( ² re.miller@elsevier.com )

Interest In Transradial PCI Grows In U.S. But Barriers Remain

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