The new guidelines are set to recommend an endovascular first strategy, even for TASC D lesions. However, TASC IIb remains unpublished as vascular surgical societies have so far failed to endorse these recommendations. A criticism levelled at TASC has been the “fundamentally flawed” decision to change the lesion categorisation repeatedly, which was described as “shifting the goalposts”
Johannes Lammer, Vienna, Austria, told CX 33 delegates that an “endovascular first” strategy for all TranAtlantic Society’s Consensus (TASC) lesions was recommended in the proposed update to the TASC II guidelines. He also said that surgical revascularisation should be reserved for specific challenging scenarios or following unsatisfactory endovascular results.
Speaking at the Lower Limb Consensus Update session, Lammer said that the update, referred to as TASC IIb, focused exclusively on the TASC lesion classification and that it has been generated to maintain the value of the TASC guidelines to practicing clinicians.
He noted that per TASC IIb, in the aorto-iliac segment, TASC A, B, C and D lesions should be initially treated with endovascular therapy (Grade B). “Surgical revascularisation should be reserved for endovascular failures (Grade C) and disadvantageous anatomy,” he said.
Lammer shared the European perspective of TASC management in 2011, and further recommended that in the femoropopliteal segment revascularisation strategies should begin with endovascular approaches in TASC A, B, C and D lesions. “Surgical revascularisation should be reserved for endovascular failures (Grade C), occlusion of the profunda femoris artery (Grade C), severe disease of the common femoral and profunda femoris artery (Grade C) and occlusion of the popliteal artery with concomitant infrapopliteal disease (Grade C),” he noted.
“It is important to note that TASC IIb is based on the level of available evidence, advances in technology and practice patterns and does not relate to the clinical relevance,” he said.
Infrapopliteal artery disease
Lammer told delegates that “Given the expanding role of endovascular therapy for infrapopliteal disease, the classification of infrapopliteal disease as a separate anatomic region has been identified as a new addition to the TASC guidelines.”
He told delegates that in patients with critical limb ischaemia, the following recommendations apply:
- Endovascular therapy is the preferred revascularisation strategy for TASC A, B, and C lesions (Grade C)
- TASC D lesions may be initially managed by an endovascular strategy, weighing overall risks and benefits versus an initial option of surgical revascularisation (Grade C)
- Surgical revascularisation should be considered in endovascular failures with persistent critical limb ischaemia (Grade C); TASC D lesions with flush occlusion of the origin of tibial vessel to be treated (Grade C) and occlusion of the distal popliteal artery extending into the origin of the target tibial artery (Grade C)
He particularly emphasised that the TASC writing committee continues to highlight the limitations of the current literature which compares endovascular and comparative surgical techniques. “There is a strong limitation of meaningful Grade A data comparing surgical to endovascular strategies and conclusions in the current literature were highly influenced by ‘expert opinions’ and practice patterns without any scientific evidence,” he said.
Previously in the session, Iris Baumgartner, Bern, Switzerland, spoke on the aortoiliac and femoropopliteal TASC consensus update 2011. “The TASC lesion classification was developed to define the typical anatomic disease pattern that would support recommendations for various revascularisation strategies,” she said.
With TASC A lesions showing excellent results from endovascular treatment and TASC D not yielding good enough results with endovascular methods to justify them as primary treatment, the classification was looked at as a representation of the revascularisation strategy. This was the same in TASC I, II and IIb, she noted.
She pointed out that due to the continued evolution of technology available for the endovascular treatment of peripheral artery disease and the expanding skill level of many endovascular specialists across multiple disciplines, an ongoing shift in clinical practice favouring an “endovascular-first” approach for more complex anatomies was taking place.
Baumgartner explained that a revision in the classification resulted in the reclassification of more complex anatomies into lower categories (for e.g. TASC C lesions re-classified as TASC B lesions) in order to justify endovascular therapy because TASC B lesions were recommended for an endovascular revascularisation. “So depending on certain patient circumstances, the anatomy can be suited to the revascularisation strategy,” she said.
She told delegates that based on the ongoing advances in technology and practice patterns, the TASC steering committee convened in Örebro, Sweden in May 2009, aiming to get a revised contemporary consensus, referred as TASC IIb. “The first manuscript was sent to all vascular societies for endorsement in July 2010. But vascular surgical societies have been unable to endorse the document. Their main argument has been that in real life, selection between endovascular and open surgery do not follow the recommendations. This has resulted in a revised manuscript being finalised in January 2011 in order to include concerns that the document should not just represent what can be done with any method in the most skilled hands, but provide advice for both highly skilled centres and everyday practice. The revision, which has not yet been endorsed by all societies will include the influence of disease severity (intermittent claudication vs. critical limb ischaemia) on decision-making. It is important to note that an “endovascular first” strategy for a majority of patients, is recommended reserving surgical revascularisation for complex anatomy or following unsatisfactory endovascular result,” Baumgartner noted.
Changing of goal posts
Roger Greenhalgh, CX programme chairman got a round of applause when he said there was a fundamental flaw in the design of the classifications because there had been a changing of goal posts over time. “The re-design favours every sort of lesion anatomy to suit an endovascular approach, and this to me suggests that there is a shifting of the goal posts as previously the TASC classification was based strictly on the anatomy of the pathology, and was not geared towards any particular approach,” he said.
Greenhalgh wrote in the CX Consensus Update: “In the past we have considered TASC for the various lesions A, B, C and D. This year, it was reported that there was indecision between the societies, with the consequence that findings emerged with great reluctance from the speakers who were under orders not to make the results known publicly. In addition, it emerged that since 2000, with update in 2008, the anatomy of TASC lesions has changed.
Apparently, the change of the anatomical lesion definition is towards an expected outcome of therapy, such that a particular TASC lesion is managed entirely by endovascular methods or not. It is a moot point whether the lesion should change or whether the proportion of endovascular treated patients is seen to increase using the same anatomical definition which we have grown to understand. This is a fundamental issue and many of the audience favoured that the lesion should stay the same so that they could see the change proportioned over time.”
The session was chaired by Frans Moll, Utrecht, The Netherlands. He stated that the dilemma the TASC group faced was 1) coming up with a classification system which covered all categories and risked becoming too complicated for common use, or 2) outlining one that was simple to use but which would draw criticism.
Patrick Peeters, Bonheiden, Belgium questioned whether new flexible and long stent designs demanded an update of the TASC femoropopliteal recommendations. He said results from new investigational stents might further expand endovascular possibilities. This evolution is made possible by new stent design and a one-stent approach using longer stents, he noted. “Improvements in stent designs have yielded improved results. For instance, longer stents have less overlap zones, less fractures and show better results. First generation stents are relatively short and stent overlap is often required to cover total lesion length. This results in increased stiffness and fracture risk at the region of stent overlap. However, the latest generation stents are up to 20cm and this results in a decreased fracture risk,” he said.