Evidence - Aortoiliac TEA in bilateral peripheral arterial occlusive disease stage IIb

Critical limb ischaemia

Limb ischaemia can be divided into an acute and a chronic form. The diagnosis of acute ischaemia must be made promptly, and immediate revascularisation is necessary in most cases. Chronic critical limb ischaemia is the most severe form of peripheral arterial occlusive disease (PAOD). It is characterised by rest pain, or necrosis or gangrene.

Acute limb ischaemia (ALI) represents an acutely occurring hypoperfusion of the limb that is no more than 2 weeks old. It is usually caused by embolisation or local thrombosis on the basis of a pre-existing pathology such as PAOD.

Chronic limb ischaemia (CLI) denotes rest pain or ischaemic skin lesions such as ulcers or gangrene (Fontaine stage III and IV, or Rutherford categories 4–6). It has a strong association with cerebrovascular and cardiovascular events. Chronicity is defined as a symptom duration of more than 2 weeks.

TASC II criteria

The TASC II consensus document (Transatlantic Inter-Society Consensus for the Management of Peripheral Arterial Disease) addresses aspects of revascularisation in PAOD [1]. According to the TASC criteria, therapeutic treatment options can be derived depending on the length of the local occlusion/stenosis. The length of the stenosis and its localisation regions determine the therapy: endovascular or open vascular surgery.

TASC criteria for aortoiliac vascular occlusions:

TASC criteria for femoropopliteal vascular occlusions:

There are no recommendations for the morphological characterisation of the infrapopliteal segments.

Guidelines

In the S3 guideline of the German Society of Angiology/Society for Vascular Medicine on the diagnosis, treatment and follow-up of PAOD, the following, among others, is noted regarding CLI [2]:

• The primary goal in CLI is rapid and adequate revascularisation, irrespective of the treatment techniques employed.
• In multilevel lesions, the elimination of inflow obstructions takes priority over the treatment of downstream lesions.
• In CLI, inflow and subsequently outflow lesions should be treated by interventional therapy wherever possible.
• A combination of open surgical procedures and intraoperative endovascular treatment is advisable when high-grade stenoses or occlusions of the common femoral artery and the profunda femoris artery coexist with lesions in the aortoiliac inflow tract and/or the femoropopliteal outflow tract (hybrid procedure).
• Endovascular treatment should be preferred when the angiomorphological findings suggest that, in terms of technical success, a result comparable to that of open surgical therapy can be achieved.
• Endovascular interventions should be preferred when comorbidity results in an increased operative risk for the comparable surgical procedure.
• Endovascular procedures should be performed primarily in the treatment of femoropopliteal lesions. In a TASC D situation without increased operative risk, without appreciably reduced life expectancy, and with an autologous vein available, bypass procedures should be preferred.
• For lesions of the popliteal artery, balloon angioplasty should be performed primarily.
• In patients with critical ischaemia, infrapopliteal vascular lesions should be treated primarily by endovascular means. Vascular surgical procedures may be considered provided the operative risk is acceptable and an autologous vein is available.

The recommendations of the European Society of Cardiology (ESC) in collaboration with the European Society for Vascular Surgery (ESVS) for patients with CI and CLI include, among others [3]:

1. Revascularisation of aortoiliac occlusive lesions

• For short lesions < 5 cm, an endovascular-first strategy is recommended.
• For aortoiliac occlusions, aorto-(bi)-femoral bypass should be considered provided the patients are surgically fit.
• In patients with severe comorbidity, an endovascular strategy should be considered for long-segment and/or bilateral occlusions.
• For aortoiliac lesions, with appropriate expertise, an endovascular intervention may be performed as the first measure provided a subsequent surgical option is not compromised.
• For an aortic occlusion extending up to the renal arteries, open intervention should be considered provided the patient is fit.
• A hybrid procedure – iliac stenting combined with femoral endarterectomy or bypass – may be considered for iliofemoral occlusions.
• In the absence of alternatives for revascularisation, an extra-anatomical bypass may be considered.
• Primary stent implantation should be considered rather than provisional stenting.

2. Revascularisation of femoropopliteal occlusive lesions

• An endovascular-first strategy is recommended for short occlusive lesions (< 25 cm).
• Primary stenting as well as drug-coated balloons may be considered for short-segment lesions (< 25 cm).
• Drug-coated balloons may be considered for the treatment of in-stent restenosis.
• Bypass surgery is indicated for long (≥ 25 cm) lesions of the superficial femoral artery, provided the patients are not at high risk for a surgical procedure, an autologous vein is available, and life expectancy exceeds 2 years. For patients who are not fit enough, endovascular therapy may be considered.
• For the femoropopliteal bypass, the autologous saphenous vein is the bypass material of choice.

The guidelines of the American College of Cardiology (ACC) and the American Heart Association (AHA) give, among others, the following recommendations for CLI [4]:

• In CLI patients, revascularisation should be performed wherever possible in order to minimise tissue loss.
• Prior to amputation, an interdisciplinary team should assess the options for revascularisation.

1. Endovascular revascularisation

• Endovascular interventions are recommended to restore perfusion to the foot in patients with non-healing wounds or gangrene. In ischaemic rest pain, a staged approach to endovascular procedures is recommended.
• An angiosome-directed endovascular treatment may be considered in patients with CLI and non-healing wounds or gangrene.

2. Surgical revascularisation

• If a bypass to the popliteal or infrapopliteal arteries is planned, it should be performed with an autologous vein.
• Surgical procedures are recommended to restore blood flow to the foot in patients with non-healing wounds or gangrene.
• If endovascular treatment fails and no suitable autologous vein is available, a prosthetic graft may be used as a substitute.
• In patients with ischaemic rest pain, a staged approach to surgical interventions is recommended.

Results

1. Percutaneous intervention vs. bypass surgery in CLI

The largest meta-analysis on this topic to date comprises over 45 studies with a total of just under 21,000 patients and dates from 2018 [5]. The comparison of percutaneous vascular intervention (endovascular revascularisation, ER) with open bypass surgery (open revascularisation, OR) showed:

• ER reduced the risk of 30-day mortality, major adverse cardiac and cerebrovascular events, and wound infections, but increased the risk of long-term mortality and failure of primary patency.
• Compared with autologous bypasses, ER also performed worse in terms of secondary patency and led to amputations more frequently over the long-term course.

The authors of the meta-analysis concluded that OR represents the better choice for patients in good general condition and with relatively long life expectancy, particularly when autologous bypass material is available.

A 2017 Cochrane review examined the efficacy of bypass surgery in chronic ischaemia compared with other interventions (PTA, endarterectomy, thromboendarterectomy, thrombolysis, exercise training, and spinal cord stimulation) [6]:

• In the comparison of bypass vs PTA, bypasses more frequently showed early, non-thrombotic complications but were associated with a higher technical success rate.
• One year after the intervention, primary patency was higher in the bypass group than after PTA; four years later, no difference remained.
• With regard to mortality, clinical improvement, amputation rates, and reintervention rates, no differences could be identified between the bypass and PTA groups.

The authors concluded that there is only limited high-quality evidence regarding the effectiveness of bypass surgery compared with other treatment methods.

2. Sex-specific differences in outcomes following lower extremity revascularisation

A systematic review with meta-analysis examined the influence of sex on the outcomes of lower extremity revascularisation [7]. Forty studies were considered; 15 studies reported outcomes after OR, 19 after ER, and the remainder involved mixed procedures:

• Compared with men, women had a significantly higher 30-day mortality, amputation rate, early graft thrombosis, embolisation rate, complications at the access site, as well as more general complications (cardiopulmonary, cerebral).
• No differences were found with regard to reinterventions and renal complications.
• When analysing the outcomes for OR and ER, the increased risk of postoperative mortality and complications in women persisted. In the long-term outcome, however, no significant differences were found between men and women.

As reasons for the less favourable outcomes in women, the authors cite, among other things, patient age (women were older than men at the time of intervention) and an undertreatment of women, compared with men, with platelet aggregation inhibitors, statins, and cardiovascular medication.

3. Angiosome-targeted revascularisation in CLI

Angiosomes are areas of skin and tissue supplied by so-called source arteries. In the human foot there are 6 such arteries (A. plantaris medialis, A. plantaris lateralis, calcaneal branch of the A. tibialis posterior, lateral and medial branch of the A. fibularis, A. dorsalis pedis). The wound healing rate is said to be improved by direct revascularisation, i.e. by placing a bypass onto a segment directly supplying the angiosome.

A 2017 systematic review with meta-analysis on the subject of angiosome-targeted revascularisation in CLI exists, comprising nearly 4000 patients [8]. Compared with indirect revascularisation (IR), direct revascularisation (DR) significantly improved wound healing, the major amputation rate, and amputation-free survival. In a sensitivity analysis, however, the significance for the major amputation rate in bypass surgery was lost, and no differences were found between IR and DR with regard to overall survival either.

The authors concluded that the angiosome theory is supported by their analysis, at least for endovascular treatment. The outcomes between ER and IR are similar as soon as collateral vessels are present, so that patients without collaterals are most likely to benefit from DR, which is why the angiosome concept appears less useful for bypass surgery.