No Clear Choice: Angioplasty vs. Bypass For Limb Ischemia

BY JEFF EVANS

LONDON -- The decision by experts to go with either an endovascular approach or bypass surgery to treat a severe femoropopliteal occlusion may depend heavily on what outcomes are deemed to be the most important.

There is a clear lack of evidence for the superiority of either type of procedure, which has left experts in different fields to interpret the studies through different lenses, according to arguments presented by speakers on each side of the debate at the Charing Cross 28th International Symposium.

Treating 'Stable' vs. 'Critical' Ischemia

The manner in which patients present themselves with critical limb ischemia is very important in determining how to treat them, said Dr. Jim A. Reekers.

Patients with femoropopliteal lesions defined as type D by the TransAtlantic Inter-Society Consensus (TASC) will present with nonhealing ulcers, gangrene, and sometimes with pain.

Such patients are "stable" when they have severe claudication but can still move around and have friends, neighbors, or caregivers helping them.

Their ischemia becomes "critical" when a small skin defect or an infection creates a demand for blood that cannot be matched.

For these patients, "it's very important to treat symptoms and not anatomy," said Dr. Reekers, who is professor of interventional radiology at the University of Amsterdam.

Interpreting the BASIL Trial

The results from the bypass versus angioplasty in severe ischemia of the leg (BASIL) trial showed that balloon angioplasty was not significantly different from bypass surgery in preventing amputation, but that angioplasty was superior to bypass surgery on secondary end points such as the length of hospital stay (Lancet 2005;366:1905-6).

THE BASIL TRIAL SHOWED THAT BALLOON ANGIOPLASTY WAS NOT SIGNIFICANTLY DIFFERENT FROM BYPASS SURGERY IN PREVENTING AMPUTATION.

Since these patients are most interested in enjoying their last years of life and want to avoid long hospital stays, surgery, amputation, and loss of independence, Dr. Reekers argued that the BASIL trial results should be interpreted to mean that an endovascular approach is the best choice for them.

But Dr. Henrik Sillesen of the University of Copenhagen noted that in the BASIL trial's composite end point of death and amputation, 75% of the end points reached were deaths and not amputations.

The BASIL trial "actually shows you how to design a trial to be negative" because the inclusion of the end point of death provided "75% of the power," even though the treatments are not meant to prevent death. This makes it "almost impossible to get a positive trial," he said.

Bypass surgery may actually confer a benefit, because in a post hoc analysis of patients in the trial who lived longer than 6 months, those who received bypass surgery had significantly longer amputation-free survival than those who received balloon angioplasty.

The results of the BASIL trial appear to confirm what was already known, according to Dr. Sillesen: Angioplasty provides limited patency, mortality is high in patients with critical limb ischemia, and surgery is superior to endovascular techniques in patients who expect to live longer than 6 months. "How many of your patients do you actually treat where you think they will live less than 6 months?" he asked.

Success With Subintimal Angioplasty

Subintimal angioplasty has several advantages over conventional angioplasty in that one can reconstitute bi- and trifurcations and perform procedures on tandem lesions in the same leg during the same session, said Dr. Amman Bolia of the department of radiology at Leicester Royal Infirmary (England) where subintimal angioplasty was first practiced.

On the one hand, conventional angioplasty itself has many advantages: It is repeatable, minimally invasive, performed under local anesthesia, can be performed at a late stage of disease, and does not compromise future surgery.

On the other hand, compared with conventional angioplasty, bypass surgery has disadvantages: It is performed under general anesthesia, may require a longer length of stay in the hospital, and can result in technical difficulties such as an infected, ulcerated, or edematous leg.

In addition, patients also may have unsuitable veins for bypass, Dr. Bolia said.

In patients with critical limb ischemia or claudication, subintimal angioplasty has reportedly had 74%-92% primary success and patency ranging from 33% to 92% at 1 year and 59% to 65% at 2 years.

A patency rate of 64% at 5 years has been reported in one series, which may be attributed to good surveillance (Eur. J. Vasc. Endovasc. Surg. 2004;28:645-50).

"All subintimal angioplasties should undergo surveillance if possible to deal with any stenotic lesions," Dr. Bolia advised.

The limb salvage rate of subintimal angioplasty for patients with TASC D lesions is about 90% at 1 year, and has been reported to be 88% at 3 years. In most cases, these lesions had a mean length of occlusion of 10 cm or longer, according to Dr. Bolia.

Investigators who used subintimal angioplasty in a study of 50 limbs with critical limb ischemia or claudication in 46 patients were able to improve their results during the course of the study.

In the first 25 limbs, the investigators reported 64% success but then had 92% success in the second set of 25 (Eur. J. Vasc. Endovasc. Surg. 2002;24:524-7).

"Clearly, this indicates that there is a learning curve and with the curve you can actually improve your results substantially," Dr. Bolia said.

In one retrospective study, investigators at a single center found that their 10-year cumulative limb salvage rate of 72% with bypass surgery increased to 86% when they switched to performing subintimal angioplasty during the last 5 years (Eur. J. Vasc. Endovasc. Surg. 2005;30:291-9).

"To me, that's the most convincing paper that's come out" that shows subintimal angioplasty is the "way forward," he said.

Poor Patency Rates With Angioplasty

The short and long-term primary patency rates of percutaneous transluminal and subintimal angioplasty are too low and variable among institutions to make them reliable procedures, countered Dr. Marc Bosiers, head of the department of vascular surgery at St. Blasius Hospital, Dendermonde, Belgium.

Dr. Bosiers cited 1-year primary patency rates as low as 22% for superficial femoral artery occlusions 15 cm or greater in length (J. Vasc. Interv. Radiol. 2003;14:997-1010). Primary patency rates at 5 years have ranged from 50% to 80% for bypass surgery but only 12% to 25% for angioplasty.

The results of one randomized trial, despite having recruited only 56 patients instead of the intended 200, showed that the primary patency of bypass surgery for femoropopliteal TASC D lesions at 1 year was significantly higher than percutaneous transluminal angioplasty (82% vs. 43%), according to Dr. Sillesen.

Those results translated into an absolute risk reduction of 31% (Eur. J. Vasc. Endovasc. Surg. 2004;28:132-7).