What is the evidence that tibial angioplasty works?

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Peter Schneider told delegates at the Society for Vascular Surgery (SVS) Annual Meeting, in Boston, that tibial artery angioplasty has benefits when compared with the standard of care, bypass surgery, and therefore should be considered the first approach in appropriate patients.

Led by advances in technology and techniques, an endovascular-first approach in appropriate patients has gradually gained acceptance, Schneider told the audience at the SVS congress. “Specific trends are fostering this development. One such trend is that a skilled workforce of specialists with a strong interest in limb salvage and facility with the most sophisticated endovascular techniques has reached a critical mass in the USA and many places around the world.  Salvage can be achieved with these techniques at rates that are similar to bypass, if the right patients are selected. In addition to these trends, we now have a better understanding of the limited life expectancy and challenges facing the critical limb ischaemia population, and we also have much better tools at our disposal that have been adapted for the endovascular treatment of tibial occlusive disease,” he said.

 

“There are some unique factors about the tibial vasculature. Tibial lesion length does not seem to be as important in determining results, like it is in the iliac artery or superficial femoral artery. The tibial bed is the only arterial segment where long-term patency seems to be less important, and limb salvage can be achieved in many cases, even when patency is limited. We can also treat multiple inflow arteries at once,” Schneider explained. He said that tibial bypass is terrific for improving perfusion but not ideal as an overall treatment, due to peri-operative morbidity and mortality, limited conduit, poor functional outcome and also because not everyone is a bypass candidate. “Wound problems cause prolonged hospital stay and out-patient treatment,” he said. “Although we perform many bypasses in our practice, we tend to use it for patients with major foot damage and/or poor anatomy for endovascular intervention, such as an isolated pedal target.”

 

 The BASIL (Bypass versus angioplasty in severe ischaemia of the leg) trial, Schneider told delegates, showed that patients presenting with severe limb ischaemia, lower limb bypass and balloon angioplasty were associated with broadly similar outcomes in terms of amputation-free survival. However, he added, “BASIL was not a modern endovascular trial. It randomised patients from 1999 to 2004, 20% of cases presented immediate angioplasty failure, one-third of patients screened were not considered possible to revascularise and only about a quarter of the endovascular cases included tibial angioplasty. There has been dramatic advance in the tools and approaches to tibial disease since 2000. Nevertheless, in patients with acceptable anatomy for endovascular approaches, the two therapies were competitive, even at that time.”

 

 A study of 993 critical limb ischaemia patients conducted by Faglia and colleagues from Milan concluded that angioplasty should be the first choice revascularisation procedure for limb salvage, Schneider told the audience. “The major amputations rate was 1.7%. At five years, primary patency was 88%. During follow-up patients died at a rate of 7% per year,” he said. Schneider also mentioned studies conducted in the USA and the UK that showed that infrapopliteal angioplasty is safe and effective for critical limb ischaemia patients.

 

Schneider showed results of a meta-analysis published in the Journal of Vascular Surgery in 2008 by Romiti et al from Brazil which included 30 studies. “At three years, the primary patency was much better for bypass (72%) than for angioplasty (49%). However, the limb salvage rate of 82% was identical with both therapies,” Schneider added.

 

In conclusion, Schneider said, “Tibial intervention heals ulcers and gangrene, and results will likely continue to improve.” He added that foot damage seems to determine outcome to a greater degree than which therapy is used to improve perfusion. “My sense is that the earlier we find patients that need revascularisation, before the wound has blossomed into major tissue loss or deep infection, the more likely it will be that those patients are good candidates for endovascular intervention… and many patients can go home on the same day. The issue is not whether intervention works but which patients to consider,” he concluded.

Experts discuss the role of endovascular approach

Vascular News asked participants in the session ‘Interventions for the tibial arteries’ to comment on the data on tibial angioplasty. Donald Jacobs (St Louis University Medical Center, St Louis, USA), Vikram Kashyap and Sean P Lyden (Cleveland Clinic , Cleveland, USA), Sean Roddy (Albany Medical College, Albany, USA), and Murray Shames (University of South Florida Vascular, Tampa, USA) share their thoughts.

 

How do you analyse the results presented so far placing tibial angioplasty as first treatment for limb salvage?

Donald Jacobs: The data are quite good for limb salvage but patency is not as well supported by data. What is reported is single centre data with limited follow-up. Also confounding the data is the fact that many patients in the studies have had significant inflow procedures in the femoral-popliteal and even iliac locations. This makes it difficult to know the impact and long-term status of the tibial intervention, particularly when the endpoint is limb salvage.

 

The ability to treat complex tibial lesions has come a long way with new balloon technology and there is the potential for further improvement in acute and long-term results with further advances such as the force focus angioplasty balloons. From a cost-effective standing, primary percutaneous transluminal angioplasty for tibial disease is an excellent first line therapy.

Vikram Kashyap: Tibial and pedal bypass have been shown to be effective in preventing limb loss, but can be associated with perioperative risks including myocardial infarction and death. I agree that an “endovascular first” strategy makes sense in many of our elderly patients with severe comorbidities and tibial occlusive disease. Even though an endovascular first strategy may apply to many patients, this should not be equated with an “endovascular only” strategy. Patients need ongoing scrutiny of the treated arteries and the limbs that they are supplying. Clinical failure often with ongoing tissue loss mandates re-intervention and/or surgical revascularisation for limb salvage.

Sean Lyden: The data continues to mount documenting the efficacy of tibial angioplasty. Use of endovascular approaches as the first line therapy is well accepted by practicing physicians today. There are now multiple therapeutic options for treating critical limb ischaemia with endovascular approaches. Unfortunately there is no data comparing outcomes between available devices. Choices of cutting balloons, plain old balloon angioplasty, cryoplasty, atherectomy, and stenting all exist. No one currently knows which device is best and best used under what types of anatomy.

Sean Roddy: Individuals with extensive foot ischaemia may have the best results with open reconstruction. Regardless of approach, close follow-up is necessary to achieve the most optimal outcome.

Murray Shames: Tibial angioplasty durability is still a concern; however limb salvage rates are comparable with surgical revascularisation. The evidence suggests that many recurrent lesions can be treated with secondary endovascular procedures, and that angioplasty can be used repeatedly even in tibial vessels. Interventionalists need to take into account lesions characteristics, TASC criteria, calcifications, number of vessels to be treated when assessing a patient for tibial angioplasty. Another critical factor is the reporting standards used in the literature. Patency should ideally be reported based on vessel imaging and not using terminology like target lesion revascularisation, target vessel revascularisation, or clinical data (pulse exam, change in ankle brachial).

 

What is the next step in the comparison between tibial bypass and endovascular treatment?

Jacobs: The ability to conduct a prospective, randomised trial to answer this is unlikely. The confounding impact of concomitant inflow procedures required in many or most patients would be difficult to separate out. The difficulty in getting patients to enrol in a trial of procedures of such different invasiveness would be challenging.

 

Comparison of endovascular techniques to historical data on bypass seems very reasonable. The challenge is to conduct a trial of angioplasty that can take into consideration the multilevel disease with detailed lesion characterisation and good follow-up that includes data on patency and need for further intervention, as well as limb salvage.

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Kashyap: The BASIL trial provides rationale for applying angioplasty in patients with limb ischaemia. Further trials will help synthesise lesion anatomy, morphology, and clinical variables to determine the best treatment for patients with specifically tibial occlusive disease. In the interval, careful application of endovascular therapies is appropriate.

Lyden: The physicians agreed that further industry sponsored data comparing differing technologies is unlikely to ever happen. An NIH or government sponsored study may be the only way ever to get to the true data. For rest pain, minor or moderate tissue loss interventional therapy is now the standard approach. The physicians also felt that in the setting of severe tissue loss and gangrene that open surgical therapy still represented the best option for revascularisation.

Roddy: The lower peri-procedural morbidity after endovascular therapy makes percutaneous intervention greatly desirable. However, bypass is associated with higher potential for limb salvage. Comparison of outcome based on extent of tissue loss, availability of autogenous conduit, and patient comorbidity may help each practitioner decide which treatment option is best.

Shames: An ideal comparison would be a randomised trial comparing bypass to angioplasty. This would be a difficult task given the diversity of training of interventionists currently performing tibial angioplasty. Perhaps a registry database with strict entry criteria and standardised surveillance protocols would provide adequate data.

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