'Plain Old Pedal Bypass' Still Useful

BY MARK S. LESNEY

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"Plain old pedal bypass" remains an important mainstay in the safe treatment of diabetic ischemia and should not be lost in the confusion of how best to define and treat this type of vascular disease.

The difficulty with foot problems is that there is a wide spectrum of clinical presentation, as well as a tremendous difference in the treatment requirements for patients with tissue loss, compared with those who only have rest pain, according to Dr. Joseph L. Mills Sr., speaking at the 2009 Diabetic Foot Conference in Los Angeles.

Different definitions exist for critical limb ischemia (CLI), and it is important to know which one is being used when evaluating treatment summaries. The United States and the European consensus definitions, for example, differ primarily in the cutoff levels of ankle systolic pressure and in toe pressure in the presence of ulceration or gangrene.

The treatment options proposed in many papers do not adhere to either definition; patients with claudication only or those with just tissue loss who don't meet these criteria often are included, said Dr. Mills, professor of surgery and chief of vascular and endovascular surgery at the University of Arizona, Tucson.

Because of these varying degrees of tissue loss, infection, and inflow and outflow conduits, it is difficult to analyze published results, yet the decision to perform an endovascular procedure or an open bypass should be critically dependent on the appropriate categorization of the level of disease, he added.

Despite the varying degrees of disease states, pedal bypass seems to work well. Although there are not a lot of data, a published meta-analysis showed that there was a primary patency of 80% for popliteal-pedal bypass surgery and foot salvage of more than 80% at 5 years, "which is extraordinarily good," according to Dr. Mills.

In comparison, Dr. Mills summarized a presentation by Dr. John F. Eidt at the Southern Vascular Surgery Meeting, comparing the results of percutaneous transluminal angioplasty (PTA) in only prospective, randomized trials with a variety of other nonsurgical techniques (including stenting) for the treatment of superficial femoral artery (SFA) disease. Dr. Eidt, director of the division of vascular surgery at the University of Arkansas, Little Rock, found that the patency with PTA is about 33% after 1 year for 5-cm lesions--"which is not very good," according to Dr. Mills. And stenting is not the definitive solution because it has a high degree of restenosis, which is an even worse problem in patients with Transatlantic Intersociety Consensus (TASC) C/D lesions, CLI, or diabetes.

Dr. Mills then reviewed the Bypass vs. Angioplasty in Severe Ischemia of the Leg (BASIL) trial, which is one of the few randomized studies that directly compare bypass with angioplasty for severe ischemia of the leg. In this study, 452 patients were randomized to surgery first (228) or angioplasty first (224). The study was flawed in many respects, according to Dr. Mills, who noted that for many of the patients, severe ischemia did not translate to CLI (some patients had pressures of 90 or 100), and a large number of patients were excluded. In addition, only 58% of the BASIL patients were diabetic, but "in our practice, almost all the patients with critical limb ischemia are diabetics," said Dr. Mills.

"The only part [of BASIL] that's been published so far--and the part that everybody quotes--is that there is no early difference [at 6 months] between open versus endo. But what they did note is that, if you happened to be alive 2 years after your index procedure, you did better if you had a bypass first."

In the long-term BASIL results, which have been presented at various meetings, the bypass-first group had significantly better amputation-free survival than did the angioplasty-first group (relative risk 0.85), and the bypass group had significantly lower all-cause mortality than did the angioplasty-first group (RR 0.65). Decreased survival was associated with higher body mass index and serum creatinine level, diabetes, age, and smoking.

"And so the argument that endo first rather than open first causes less mortality is probably not true," Dr. Mills said. He pointed out that, although an angioplasty is less invasive, it generally has to be redone, and the redo occurs in a patient in a deteriorating condition, adding to the risk.

Furthermore, there were no significant differences seen in health care costs at 5 years. The higher initial costs of surgery were counterbalanced by higher subsequent use of hospital services by the angioplasty-first group, according to Dr. Mills.

In fact, "the Achilles' heel of durability still remains for endovascular therapy in the first decade of the 20th century," he concluded.

"Does durability matter? We've heard that it doesn't," said Dr. Mills. Using data from his own CLI patients who had a leg bypass, however, he demonstrated that treatment and healing can take a very long time, and a procedure that has to be redone within 6 months can be a problem.

Dr. Mills stated that the choice of treatment is a complex decision-making process, based on the size and location of the lesion, the extent of comorbidities and infection in the patient, the estimated life span, and many other factors.

Despite what he believes are some imperfections, the most thoughtful algorithm published for this decision-making process is the Lower Extremity Grading System (LEGS) score, which takes into account demographic findings, presentation, functional status, comorbidities, and technical factors (J. Vasc. Surg. 2004;39:1268-76).

Dr. Mills then criticized what he considered to be "irrelevant end points" in vascular studies. These included the target artery revascularization rate, which could be excellent but is clinically irrelevant to the patient; creating "in-line flow," because an angiographically patent channel with an inadequate hemodynamic result still is a failure; and "secondary patency," which can "almost always be achieved if the interventionalist is persistent enough; despite the fact that multiple serial revascularization procedures potentially harm patients," he said.

"It is unquestionably true that even conservatives like some of us are treating at least half our patients with endovascular therapy, and for many of those patients, it is less morbid. But I don't think endovascular therapy should be used for everyone. There is no question that if you have a TASC A and TASC B lesion in the SFA, that gets endo first. TASC C, I think, depends not on what your technique is, but on what the patient is. How many comorbidities do they have? How good are their veins? What's their expected longevity? ... If they have long-segment disease, which in my experience most diabetics have, they do better with a vein graft to the foot," he said.

"Pedal bypass is still a safe haven for patients. I don't think every patient needs a pedal bypass, but I don't think that they should be forced to go through two or three endovascular failures first before they get one," he concluded.

Dr. Mills disclosed no conflicts of interest related to his presentation.

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