Have Endovascular Advances Reinvented Limb Salvage Expectations?

In the early 1980s, LoGerfo opened the window of limb salvage in critical stages of diabetic atherosclerosis by fighting the misconception of microangiopathy that had previously prevented attempts to bypass arterial lesions in diabetic foot.1 He produced evidence that revascularization of distal diabetic arterial occlusions can be successful. This evidence in turn gave a fundamental push to expand and improve techniques of distal bypass.2,3
   Physicians then applied the same techniques for the treatment of non-diabetic atherosclerosis to diabetic atherosclerosis. At this time, the concept of critical limb ischemia (CLI) emerged and limb salvage was the expected goal. Soon we saw that long-term results of distal revascularization in patients with diabetes were not inferior when physicians measured them in terms of limb salvage. This boosted the practice of distal bypass for diabetic arterial lesions.
   Subsequently, researchers observed that following distal bypass in patients with diabetes, physicians could salvage limbs despite the vessels’ reocclusion. Consequently, bypass patency rates have been consistently lower than limb salvage rates over
the years as reported in the literature.

How Endovascular Approaches Have Evolved Over The Years

In the last 10 years, improvements in techniques and materials helped us to extend the endovascular approach to distal vessels successfully. In addition to the efficacy of the endovascular approach, it is a simpler technique for various specialists to master and patients widely prefer an endovascular approach to bypass surgery. These factors, among others, have helped in the consequential widespread applications and indications for endovascular techniques.
   Today, most centers routinely perform femoral, popliteal and tibial endovascular interventions. Accumulated data supports this practice and shows evidence of the immediate efficacy of these interventions.4 The effect of this phenomena and the current trend of its practice have pushed the endovascular approach further distally, so much so that sometimes surgeons perform single tibial interventions in patients with diabetes and CLI.5-7
   Most studies on revascularization procedures today insist on either limb salvage or major amputation-free survival as the primary efficacy endpoint. Ulcer healing is seldom considered to be a criterion for success.8
To this endpoint, results may appear exceptional (generally over
a 95 percent limb salvage rate) despite very poor outcomes in terms of patency of the recanalized vessels (generally below 50 percent). In addition, while the literature always claims a near 100 percent limb salvage rate, there is a consistently high number of “minor amputations” (reportedly up to 48.6 percent) cited alongside of this figure.9
   We experience the same outcome in our center, where the endovascular approach to the ischemic diabetic foot leads to a 96 percent one-year limb salvage rate despite a 76 percent to 86 percent targeted vessel patency rate according to the technology (PTA/stent versus endoluminal laser assisted atherectomy) vascular surgeons have applied.

Should We Reevaluate Our Criteria For Limb Salvage Success?

Despite the effort invested in diabetic foot revascularization, how much of the foot do surgeons save? Clinical studies have limb salvage as a primary goal while foot amputations are only a collateral observation.
   In revascularization studies on diabetic arterial disease, should we really be talking about CLI? We all have seen that a patient with diabetes may lose only a toe in the presence of repeated sequential arterial lesions or lose a whole limb with good pedal pulses. In light of this, should we propose a different clinical classification for diabetic peripheral vascular disease with respect to the current classification, which includes all patient populations?
   In the diabetic population, should the efficacy criteria of revascularization therapy be limb salvage? Given the current technology, which currently allows us to perform lower risk interventions to distal vessels in patients whose arterial disease is less than critical, why not aim for foot salvage?
   Does foot salvage mean salvage of the functional foot? If everyone agrees that foot ulcer prevention is a must in patients with diabetes and if vascular specialists can successfully treat single tibial vessel occlusion in the presence of signs of trophic lesions in the diabetic foot, we propose a more preemptive action. Functional foot salvage should be the primary endpoint by which one should measure the effectiveness of any proposed therapy in these clinical studies.
   To this end, we need the multidisciplinary foot salvage team to work together with podiatrists in the lead to define the edge of the functional foot. This would be the threshold where the loss of tissue begins to compromise foot action. With this new concept in mind, we should propose a new classification for diabetic peripheral vascular disease and consequently use a new paradigm for clinical observation. The brief table, “A New Classification For Saving The Diabetic Foot” (see above), can start an open discussion of these issues.

In Conclusion

Once we take the aforementioned actions, we can truly begin to measure the effectiveness of newer revascularization strategies and techniques (such as single tibial treatment, specially dedicated tibial devices, high tech angioplasty balloons, smart stents, lasers and gene therapy) that are being proposed in preemptive stages of the arterial disease.
   In this way, we do not persist to measure limb salvage in clinical settings where limbs were never threatened. We also will not keep referring to minor foot amputations as successes when tissue loss of the foot is what we are trying to avoid.
We need to build up evidence-based data to support the exciting new technology that is opening up to us to save the foot.

Dr. Serino is the Chief of the Endovascular Surgery Program, Diabetic Foot Team at the Istituto Dermopatico Dell’Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico (IDI IRCCS) in Rome, Italy.

Dr. Cao also practices at the aforementioned institution in Rome, Italy.

Dr. Steinberg is an Assistant Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. Dr. Steinberg is a Fellow of the American College of Foot and Ankle Surgeons.

References:

1. LoGerfo FW, Coffman JD. Current concepts. Vascular and microvascular disease of the foot in diabetes. Implications for foot care. N Engl J Med. 1984 Dec 20;311(25):1615-9. 2. LoGerfo FW, Corson JD, Mannick JA. Improved results with femoropopliteal vein grafts for limb salvage. Arch Surg. 1977 May;112(5):567-70. 3. LoGerfo FW, Haudenschild CC, Quist WC. A clinical technique for prevention of spasm and preservation of endothelium in saphenous vein grafts. Arch Surg. 1984 Oct;119(10):1212-4. 4. Faglia E, Clerici G, Clerissi J, et al. When is a technically successful peripheral angioplasty effective in preventing above-the-ankle amputation in diabetic patients with critical limb ischaemia? Diabet Med. 2007 Aug;24(8):823-9. 5. Sigala F, Menenakos CH, Sigalas P, et al. Transluminal angioplasty of isolated crural arterial lesions in diabetics with critical limb ischemia. Vasa. 2005 Aug;34(3):186-91. 6. Feiring AJ, Wesolowski AA, Lade S. Primary stent-supported angioplasty for treatment of below-knee critical limb ischemia and severe claudication: early and one-year outcomes. J Am Coll Cardiol. 2004 Dec 21;44(12):2307-14. 7. Faglia E, Mantero M, Caminiti M, et al. Extensive use of peripheral angioplasty, particularly infrapopliteal, in the treatment of ischaemic diabetic foot ulcers: clinical results of a multicentric study of 221 consecutive diabetic subjects. J Intern Med. 2002 Sep;252(3):225-32. 8. Hoffman U, Hulte KL, Heidrich H, et al. Complete Ulcer healing as Primary Endpoint in Studies in Critical Limb Ischemia? A critical reappraisal. Eur J Vasc Endovasc. Surg 33,311-316; 2007. 9. Faglia E, Dalla Paola L, Clerici G, et al. Peripheral angioplasty as the first-choice revascularization procedure in diabetic patients with critical limb ischemia: prospective study of 993 consecutive patients hospitalized and followed between 1999 and 2003. Eur J Vasc Endovasc Surg. 2005 Jun;29(6):620-7.