Luciano Pedrini, Maggiore Hospital, Bologna, Italy, takes TASC II to task
The first TASC guidelines produced a good review of published papers, and had an impressive impact on the behaviour of many vascular surgeons and interventional radiologists. But, above all, it introduced the morphological classification of arterial lesions that allowed us to effectively characterise patients.
This was useful to try to improve the evaluation of our results and to stratify patients following homogenous categories. Many papers published in the last few years refer to these categories, especially with regard to endovascular treatment. So, the first TASC was particularly useful for vascular specialists, giving new methodology and denouncing the lack of studies to produce strong recommendations.
The TASC II document, however, is quite different. It is not written like a classical guidance document: many recommendations refer to secondary aspects; the evaluation of literature was not systematic; and the text – sometimes descriptive and sometimes analytic – rarely supports the recommendations.
The classification of critical limb ischaemia, for example, returned to a descriptive definition. After more than 25 years of utilisation of the haemodynamic parameters to support the diagnosis of critical limb ischemia, the TASC II authors could not find a consensus regarding the critical level for ankle brachial pressure index, toe pressure, and TcPO2, as different patterns of proximal, distal, and foot or finger arterial occlusions can be responsible for this clinical event.
Investigation of microcirculation and macrocirculation is recommended to support the diagnosis of critical limb ischaemia. Nevertheless, the determination of TcPO2 seems to keep a role in patients with falsely elevated ankle brachial pressure index; 30mmHg is considered the critical value. Moreover, the measure of TcPO2 combined with clinical determination may be of value to predict healing at various levels of amputation.
Regarding medical treatment with prostanoids, the two “type A” statements of TASC II’s recommendation 28 are somewhat conflicting. Recommendation 27 – about the decision to amputate and the choice of the level – states that the physician “should take into consideration the potential for healing, rehabilitation, and return of quality of life”, without stressing the necessity of evaluating the possibility of revascularization, and avoiding repeated and useless treatment.
In the chapter on acute ischaemia, the authors omitted to mention ultrasonographic diagnosis, feasible in the emergency department or at patient’s bedside, and often useful in selecting appropriate treatment. Moreover, regarding treatment of acute ischemia, the authors seem to have forgotten embolism and the “simple, cheap, and sure” Fogarty catheter, suggesting instead an expensive and occasionally life-threatening endovascular thrombolytic treatment as suitable for patients with acute thrombosis and without limb-threatening ischaemia.
Treatment of patients with claudication very probably could not be recommended either to vascular specialists or to the general practitioner. In one section the document recommends exercise rehabilitation and drugs to reduce risk factors and improve walking distance, while in another section the authors assume that endovascular treatment of infrainguinal disease in patients with intermittent claudication is an established treatment modality. This statement encourage surgeons to treat more and more people at the claudication stage (1), to improve life quality, with a modality that is still complicated by a high operative and early failure rate at femoral and infrageniculate level, and is as yet not supported by evidence.
Regarding the morphological classification, the TASC II authors changed the lesions included in the classification without modifying the classification itself, so comparison between published results will be impossible if papers do not specify which TASC classification system has been used.
Moreover, it seems difficult to assess ‘‘equivalence’’ of both open and endovascular methods for specific patients and morphologies in clinical routine and to compare published data, as patients included in surgical and endovascular trials are not equivalent in terms of indications or extent of the disease (2). The new combination of lesions classified as type D will very probably require a new subdivision, unless we agree on the inefficacy of the classification itself, as it has we have with ankle brachial pressure index and TcPO2 levels.
In the eight years between the two editions, industry has produced many devices for endovascular treatment: heparin bonded grafts; new, small endografts; stents with increased lateral strength and with greater response to compression and torsion. In the same time, many authors have published reports about these new devices/techniques, but have done so without guidance from the scientific societies comprising the TASC committee. The results are obvious: even now we do not have type A recommendations.
Moreover, results of vascular treatment should be compared with population-based data, that, till now, do not show a decrease in amputations and consequently do not support an increase of treatment in patients with intermittent claudication.
As the authors recommend TASC II to physicians in primary healthcare who see patients with peripheral arterial disease, the document should be abridged to be more accessible, and should include recommendations or information about new treatments (including their limitations). This exercise could be useful in reducing late observation of patients with critical limb ischaemia, or to see patients already treated inappropriately. Moreover, recommendations (or the full paper) should be published online and upgraded more frequently on an open website.
1. Menard MT, Belkin M. Infrapopliteal intervention for the treatment of the claudicant. Semin Vasc Surg 2007;20(1):42-53.
2. Schillinger M, Diehm N, Baumgartner I, Minar E. TASC II section F on revascularization: commentary from an interventionist’s point of view. J Endovasc Ther 2007;14(5):734-42.