SAN DIEGO - Interventional radiologists enjoy a high rate of technical success in placing endografts under image guidance to repair abdominal aortic aneurysms. But problems such as restenosis and endoleaks continue to occur, raising questions about the long-term efficacy of the procedure.
In a series of presentations at this week's Society for Cardiovascular and Interventional Radiology conference in San Diego, investigators discussed their successes and failures with the range of endografts currently on the market.
One of the newest stent-graft products is the AneuRx device from Medtronic AVE of Santa Rosa, CA. AneuRx was specifically designed for AAA and was cleared by the Food and Drug Administration in mid-1999. A group of researchers at Harbor/UCLA Medical Center in Torrance, CA, treated 171 patients with the AneuRx endograft between June 1996 and September 1999, according to Dr. Irving Walot, who presented the study.
In general, the Harbor researchers enjoyed good success with AneuRx. They successfully deployed the device in 168 patients (98%), and 99% of patients were successfully treated. The Harbor researchers found that AneuRx's modular design enabled interventionalists to treat patients with low morbidity and mortality, but endoleaks did occur in some patients. "Endoleaks are a problem," Walot said.
Another group of researchers, led by Dr. Barry Katzen of the Miami Cardiac & Vascular Institute at Baptist Hospital in Miami, has been involved in a multicenter trial of a new version of the Vanguard endograft manufactured by Boston Scientific of Natick, MA. The goal of the study is to test the safety of the device as compared to conventional open surgery.
Since starting the trials in August 1997, the group has performed 243 endograft implants, and 98 conventional surgical procedures. The mortality rate 30 days after implantation was 1.6% (4 of 243 patients) for the endograft group and 3.1% (3 of 98) for the surgical group. Overall, there was a major reduction in adverse events with the endograft group, Katzen said.
The group has encountered several issues related to endograft placement, however. One issue is stent ties, which occasionally ruptured. Another problem was encountered with the fabric covering of the stent-graft, which was found to degrade over time. It's possible that calcium rubbing against the fabric could be the cause of the degradation, although more research is needed to prove this theory, Katzen said. Boston Scientific is using the institute's experience to further refine Vanguard.
A U.K. research group had a less positive experience with Vanguard, although they were working with an older version of the design. Researchers from Freeman Hospital in Newcastle upon Tyne deployed 55 Vanguard devices between December 1995 and January 1999. Like other groups, they experienced a high success rate, with all devices deployed properly and no conversions to surgery. They reported six endoleaks, according to Dr. John Rose, who presented the study.
But over the long term, the Freeman Hospital researchers found that follow-up procedures were necessary to correct subsequent events. After two years, the group found that only two-thirds of patients are free of intervention. Rose admitted that the problems could be due to the fact that the group was using a first-generation version of Vanguard, which the group stopped deploying in mid-1998.
Experiences with other types of endografts were also covered at the SCVIR meeting. A group of researchers from UCLA Medical Center in Los Angeles presented results on the Ancure endograft from Guidant of Menlo Park, CA.
The group used the device in AAA repair of 102 patients, with success rates of 87% for bifurcated grafts, 92% for tube grafts, and 94% for aortoiliac grafts. Persistent perigraft leaks occurred in 15 patients (15%). The group found the endograft to be an effective method for treating AAA, although patients do need to be followed closely after device placement, according to Dr. Antoinette Gomes, who presented the study.
Finally, a group at the Medical University of South Carolina in Charleston reported its experiences in implanting Medtronic's Talent stent-graft in patients at high risk for conventional surgical aneurysm repair. The group deployed a bifurcated version of the graft in 45 patients between March and December 1998.
Device placement was successful in 93% of patients, with endoleaks occurring in 10% and a successful outcome in 83%. The group had a mortality rate of 2.1% at less than 30 days after placement, and 2.1% afterward, for an overall mortality rate of 4.2%. The mortality rate is consistent with that encountered in patients with multiple clinical problems. The group concluded that, on the whole, the Talent stent-graft is a reliable device for treating high-risk patients.
By Brian Casey
AuntMinnie.com staff writer
March 31, 2000
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