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Intermittent claudication caused by infrainguinal arterial disease can mostly be treated conservatively. Yet, when functional capacity is threatened, claudication may need to be treated by revascularisation. This should not be done too hastily as any kind of revascularisation may be an onset of a vicious cycle of repeated interventions, which may accelerate the otherwise benign course of PAD.
SBU rapport (The Swedish council on technology assessment in health care): benartärsjukdom – diagnostik och behandling. Elanders Infologistics Väst AB,
Mölnlycke2007
Patients with critical limb ischemia (CLI) represent less than 5% of symptomatic peripheral arterial disease. In younger age groups, CLI is encountered typically in diabetics and there are a number of ischemic and neuro-ischemic lesions in this group of patients which do not meet the strict definition of CLI. The risk for amputation at a metatarsal or higher level is 8-fold higher in diabetics compared to nondiabetics.
Incidence of lower-limb amputation in the diabetic and nondiabetic general population: a 10-year population-based cohort study of initial unilateral and contralateral amputations and reamputations.
In this patient group the 5-year survival of patients <65 years old was 60% while it was 48% in older patients in Helsinki.
This is why a durable revascularisation should be used to allow wound healing in this young group of patients. In-line arterial flow to the pedal level offers the best results in patients with CLI as shown by the 10-year data from Pomposelli et al. with results from 1032 limb salvage bypasses to dorsalis pedis artery in 865 patients.
Patency is a direct measure of revascularisation success when reopening or bypassing occlusions. Patency is the key criterion for judging the primary effectiveness of a revascularization but less often described than leg salvage and amputation-free survival, or even wound healing, quality of life and sustained ambulation. Patient-related outcomes are, of course, important but strongly affected by other measures than treatment modality itself.
Leg Survival or Leg Salvage
Leg salvage or foot preservation, a favoured and easy to retrieve endpoint of CLI studies, is problematic as a number of factors other than revascularisation affect the outcome. Leg salvage is an indirect measure of the success of revascularisation. The key question is what the leg outcome would be if untreated or treated conservatively. Indeed, in studies reporting outcome of patients with CLI unsuitable for revascularisation, one year leg survival rates of 54% (CLI verified by ankle pressure <50 mmHg or toe pressure <30 mmHg),
The results of any revascularisation should be compared with these data. Four large recent series of bypass surgery for CLI reported leg salvage rates of 88–92% at one year.
summed up the limited experience available in using distal venous arterialisation as the last resort procedure to avoid major amputation and even that method was associated with 71% leg salvage at one year (Fig. 1).
Figure 1One-year leg survival after different modes of treatment for CLI (data from references [8–10] for conservative treatment, [9] for spinal cord stimulation, [16] for venous arterialization, [14–15] for PTA and [11–13] for bypass).
We should be careful when considering the so-called patency/leg-salvage gap which seems wider in endovascular than in surgical series, i.e. occlusion of the revascularized segment leads to amputation less often after endovascular procedure than surgical bypass as summarized by Romiti et al.
This gap can be explained in different ways. One hypothesis is that leg salvage exceeding the patency of the revascularisation procedure is attributable to the early patency which provides adequate perfusion until ischemic lesions are healed. Thereafter the leg stays viable if infection is cleared and proper foot care sustained, especially with diabetic lesions. This concept may, of course, be partly true, but a more obvious explanation is that legs treated by endovascular methods have milder lesions as illustrated for instance by the impressive results of Faglia et al.
Peripheral angioplasty as the first-choice revascularization procedure in diabetic patients with critical limb ischemia: prospective study of 993 consecutive patients hospitalized and followed between 1999 and 2003.
Leg salvage is actually the improvement achieved by therapeutic measures above natural leg survival (Fig. 2).
Figure 2One-year leg salvage after different modes of treatment for CLI (leg salvage attributable to patent revascularization shown as shaded area of the column). Data from references [9] for spinal cord stimulation, [16] for venous arterialization, [14–15] for PTA and [11–13] for bypass).
PTA was still recommended for stenosis and bypass for long occlusions, but there was no consensus on therapy for short and moderate occlusions (Table 1). Endovascular therapy for infrapopliteal arterial disease is gaining acceptance as a first-line method to improve ulcer healing and limb salvage, despite lack of evidence. In a recent meta-analysis on infrapopliteal surgery and infrapopliteal endovascular interventions
with 29 and 30 studies included respectively, 88% of patients were diabetics and 88% had tissue loss among the bypass group (n = 2320), whereas 61% were diabetics and 76% had tissue loss among the endovascular group (n = 2653). No distal pressure measurement was available in this study. Primary and secondary mid-term patency rates were better after bypass, but there was no difference in limb salvage. The results of this meta-analysis are biased by the heterogeneity of indications, risk factors, number of treated arterial segments, lesion type (occlusion vs. stenosis), lesion length, lesion characteristics, and outflow. In this setting, TASC II classification of femoropopliteal lesions is not very helpful.
It is most likely that bypass groups include patients with more severe disease and only a rather small share of infrainguinal lesions are equally well treatable with either method (Table 1).
Table 1Summary of recommendations of the TransAtlantic Inter-Society Consensus II Working Group.
When both endovascular and surgical revascularisation are technically feasible, no significant difference was observed in symptomatic relief in the few RCT which included both supra- and infrainguinal revascularisations for mixed indications.
SBU rapport (The Swedish council on technology assessment in health care): benartärsjukdom – diagnostik och behandling. Elanders Infologistics Väst AB,
Mölnlycke2007
There are two RCTs including mostly claudicants with superficial femoral artery (SFA) occlusions, which suggest that surgical bypass gives better results than the endovascular approach.
BASIL trial participants. Bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial: an intention-to-treat analysis of amputation-free and overall survival in patients randomized to a bypass surgery-first or a balloon angioplasty-first revascularization strategy.
Randomized comparison of percutaneous Viabahn stent grafts vs prosthetic femoral-popliteal bypass in the treatment of superficial femoral arterial occlusive disease.
Randomized comparison of ePTFE/nitinol self-expanding stent graft vs prosthetic femoral-popliteal bypass in the treatment of superficial femoral artery occlusive disease.
Only patients with CLI or at least severe ischemia and potential candidates for either infrainguinal angioplasty or bypass were included. In this trial, 42% of patients were diabetics. Both approaches yielded similar results in terms of amputation-free survival up to two years. Surgery was associated with higher postoperative morbidity, more hospital days and higher costs and angioplasty was associated with higher need for further revascularisation procedures.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
and this was the case in 75% of the patients in BASIL Trial.
The generalizability of the BASIL Trial was audited from a sample of 456 patients with infrainguinal lesions, 236 of whom underwent a revascularization procedure but only 29% of them were suitable for randomization, i.e. treatment by either method. This finding illustrates the narrow overlap of the indications for endovascular and surgical revascularization.
The same holds particularly true with the Scandinavian Thrupass vs. Bypass Study, in which SFA occlusions were randomised between PTFE endografting and PTFE bypass grafting.
Only 4% of the SFA occlusions met the tight inclusion criteria chosen to exclude short occlusions and all lesions with unfavourable landing zones for an endograft. This illustrates the difficult balance between internal and external validity. But when comparable patients are analysed, bypass seems to give a better result.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
reported a high incidence of complications related to bypass surgery according to an American private sector database with 2.7% mortality and 18.7% major complications including 7.4% of graft thrombosis. In this extended series, complications were associated with age >80 years and poor preoperative functional status.
Thus it is difficult to use these data directly to assess the risk of bypass for patients <65 years. The complications of PTA are said to be rare and minor and not to preclude a bypass at a later date. Yet, crural interventions may have severe non-correctable outcomes.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
surgery was associated with higher number of days in hospital and the need for advanced postoperative care. The mean cost of inpatient treatment was by a third higher for bypass first than for PTA first strategy but this was true only during the first year. After two years the cost of repeated new interventions abolished this difference.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
In addition, it is unclear what the costs of unnecessary interventions are.
Loss of ambulation is also an important cause of increase in costs. Goodney et al reported a 81% sustained ambulation rate at one year in patients treated by bypass for CLI.
The approaches to maximize early detection and optimize therapy for PAD have been emphasized in the literature with the hope to lessen the number of patients with CLI.
This is absolutely true for risk factors and best medical treatment, but there is no data to show that indications for revascularisations should be extended. Regional data from southern Finland have shown that endovascular activity for CLI has been doubled during the past 5 years but without any positive effect on major amputation rates. An interesting, though biased analysis could be made using the present data to assess the effectiveness of the current practice (Figs. 1 and 2). To save one leg for a year, 3-4 legs should be treated by bypass operations and 6-7 legs by endovascular interventions. Indeed, scientific evidence is lacking to assess the true efficacy of endovascular therapy on critical ischemia.
SBU rapport (The Swedish council on technology assessment in health care): benartärsjukdom – diagnostik och behandling. Elanders Infologistics Väst AB,
Mölnlycke2007
The aim is always to revascularize the leg properly, in CLI with resulting well perfused foot to allow ulcer healing. A durable solution can be achieved by bypass using good quality saphenous vein and by ascertaining good outflow. Bypass surgery and endovascular interventions are complementary techniques for revascularization. If endovascular and bypass procedure were possible with equal outcomes, then endovascular treatments would be preferred. However the main issue, especially in younger patients, is the durability of the revascularisation, better to trust a bypass with a good vein to an artery with good outflow. Despite early peripheral arterial disease in patients <65 years old, the longevity is not shortened to an extent to allow the second best treatment of choice to be selected.
Endovascular techniques and equipment are developing rapidly but scientific evidence of these new methods is scarce. Level one evidence concerning subintimal angioplasty, drug eluting balloon, cryoplasty and other latest endovascular innovations do not exist. When available, scientific data includes mainly short case-series, and since new techniques are introduced all the time, the target is moving too rapidly to collect proper scientific data.
References
Lepäntalo M.
Salenius J.P.
Albäck A.
Ylönen K.
Luther M.
Frequency of repeated vascular surgery. A survey of 7616 surgical and endovascular Finnvasc procedures. Finnvasc Study Group.
SBU rapport (The Swedish council on technology assessment in health care): benartärsjukdom – diagnostik och behandling. Elanders Infologistics Väst AB,
Mölnlycke2007 (no 187: p. 1–704)
Incidence of lower-limb amputation in the diabetic and nondiabetic general population: a 10-year population-based cohort study of initial unilateral and contralateral amputations and reamputations.
Peripheral angioplasty as the first-choice revascularization procedure in diabetic patients with critical limb ischemia: prospective study of 993 consecutive patients hospitalized and followed between 1999 and 2003.
Randomized comparison of percutaneous Viabahn stent grafts vs prosthetic femoral-popliteal bypass in the treatment of superficial femoral arterial occlusive disease.
Randomized comparison of ePTFE/nitinol self-expanding stent graft vs prosthetic femoral-popliteal bypass in the treatment of superficial femoral artery occlusive disease.
Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial.
BASIL trial participants. Bypass versus angioplasty in severe ischaemia of the leg (BASIL) trial: an intention-to-treat analysis of amputation-free and overall survival in patients randomized to a bypass surgery-first or a balloon angioplasty-first revascularization strategy.
☆Age is an issue. Younger patients have longer life expectancy and thus need more durable treatment solutions. Out of 1725 consecutive infrainguinal revascularisations for symptomatic peripheral arterial disease (PAD) in Helsinki University Central Hospital, as many as 482 (28%) belonged to this group of patients <65 years of age.
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