Angioplasty for Treatment of Isolated Below-the-Knee Arterial Stenosis in Patients With Critical Limb Ischemia

Abstract

In this issue of the journal Mendiz et al describe a large series of below knee angioplasty procedures in patients with critical limb ischemia (CLI) and reach the conclusion that this approach represents a safe and effective treatment option. Their technical results are good although there was no direct comparison with surgical bypass. In reality, there is very little level 1 evidence comparing endoarterial revascularization with bypass surgery for patients with severe lower limb ischemia. Consequently, there remains a lack of clarity as to how we should select treatment for individual patients. This issue is particularly important in diabetics where arteries proximal to the knee joint are often spared from occlusive disease and the majority of occlusions occur distal to the tibial bifurcation. Besides relieving pain and healing neuroischemic ulcers, the most important outcome in these patients is amputation-free survival. The BASIL trial randomized 452 patients to receive surgery first or angioplasty first to treat severe limb ischemia, and follow up finished when patients reached an endpoint: either the amputation of the trial leg above the ankle or death. The results showed that at 2 years, both strategies were associated with similar amputation-free and overall survival rates as well as no difference in improvements in health-related quality of life. However, for those patients who survived for at least 2 years after randomization, a bypass first strategy was associated with a significant increase in overall survival of about 7 months and a nonsignificant increase in amputation-free survival of about 6 months. This trial also demonstrated that vein bypass grafts performed significantly better than prosthetic bypass in terms of amputation-free survival but not overall survival. The authors concluded that patients who were expected to live less than 2 years should be offered balloon angioplasty first especially if the alternative was a prosthetic bypass. However, those expected to survive beyond this time, which was about 75% of the BASIL cohort, should be offered bypass first especially if a suitable vein was available. Essentially, the decision whether to perform bypass surgery or balloon angioplasty appears to depend upon life expectancy and availability of autologous vein. Of course, it may be argued that the technology associated with endovascular treatments is continually changing and improving. Drug-eluting stents have profoundly impacted coronary disease and the lower rate of in-stent restenosis associated with their use has significantly altered practice patterns. It is tempting to think that this success may be matched in small vessel disease encountered below the knee, improving patency rates and durability; however, this has not been proven as yet. Similarly, there is little level 1 evidence to support other innovative adjuncts to below the knee angioplasty such as cryotherapy and brachytherapy. Advances have undoubtedly been made in imaging and the technology required for treating the infrapopliteal arteries and to cross lesions. However, these technical advances cannot in themselves be taken to demonstrate a likelihood of a superior longer term outcome for the patient. We believe that multidisciplinary discussions are important in assessing these patients and prior to treating such lesions. Units treating patients with CLI should have the ability to offer both surgical and endovascular treatments and make sure that medical therapy is also optimized. Assessment of the availability of adequate autologous vein is paramount in the assessment for intervention and seems to vary widely between series and may depend on willingness to use contralateral veins, arm veins, as well as individual surgical experience. Mendiz and colleagues clearly recognize the limitations of their study. Further work is urgently needed to define more precisely the role of angioplasty over surgery in these difficult patients.