Bypass surgery for chronic lower limb ischaemia

Background

The most common symptom of chronic lower limb ischaemia (inadequate blood flow to the legs) is claudication, a cramping pain caused by a poor supply of blood to the affected muscle. It often affects the calf muscle, and is typically triggered by exercise and relieved by rest. More severe restriction of the blood supply may produce pain at rest, leg ulcers, or gangrene. These conditions, and severe claudication, may require bypass surgery or other treatments to improve blood flow to the leg.

Key results

This review of eleven trials with a total of 1486 participants (current until October 2016) identified six trials comparing bypass surgery with angioplasty (balloon stretching and/or stent of the narrowed or occluded artery), and one each with remote endarterectomy (a combination of plaque removal and stent), thromboendarterectomy (removal of the plaque and clot), thrombolysis (clot dissolving), exercise, and spinal cord stimulation. In this review, no evidence was found to favour bypass surgery over angioplasty in terms of the effect on death, improvement of symptoms, amputation rate, need for further procedure, or long-term mortality. Procedural complications occurred more frequently in patients with severe leg ischaemia (rest pain, ulcers, or gangrene) undergoing bypass surgery than those undergoing angioplasty. There was evidence that bypass surgery was more often technically successful, was associated with longer hospital stay, and that the bypass graft remained open (patent) at a higher rate one year after the procedure compared with angioplasty; this difference in patency in favour of surgery disappeared after four years. There was also no clear evidence to favour bypass surgery compared with other treatments, as indicated by procedural complications and deaths, clinical improvement, vessel patency, and long-term mortality. Comparisons of bypass surgery with thrombolysis showed fewer amputations in patients subjected to bypass surgery, whereas for the rest of the comparisons the amputation rate was similar.

Quality of the evidence

In general, the quality of the evidence was high for all but two of the clinically most important outcomes. Quality of the evidence for clinical improvement was judged to be low as this was a subjective outcome at risk of bias since the outcome assessors were not blinded to the study treatments and because there were differences in results between the studies. Quality of the evidence for patency of the bypass graft was moderate because of differences in results between the studies. Further research including large numbers of participants is needed to investigate the effectiveness of bypass surgery for chronic lower limb ischaemia.

Authors' conclusions: 

There is limited high quality evidence for the effectiveness of bypass surgery compared with other treatments; no studies compared bypass to optimal medical treatment. Our analysis has shown that PTA is associated with decreased peri-interventional complications in participants treated for CLI and shorter hospital stay compared with bypass surgery. Surgical treatment seems to confer improved patency rates up to one year. Endovascular treatment may be advisable in patients with significant comorbidity, rendering them high risk surgical candidates. No solid conclusions can be drawn regarding comparisons of bypass surgery with other treatments because of the paucity of available evidence. Further large trials evaluating the impact of anatomical location and extent of disease and clinical severity are required.

Read the full abstract...
Background: 

Bypass surgery is one of the mainstay treatments for patients with critical lower limb ischaemia (CLI). This is the second update of the review first published in 2000.

Objectives: 

To assess the effects of bypass surgery in patients with chronic lower limb ischaemia.

Search strategy: 

For this update, the Cochrane Vascular Group searched its trials register (last searched October 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (last searched Issue 9, 2016).

Selection criteria: 

We selected randomised controlled trials of bypass surgery versus control or any other treatment. The primary outcome parameters were defined as early postoperative non-thrombotic complications, procedural mortality, clinical improvement, amputation, primary patency, and mortality within follow-up.

Data collection and analysis: 

For the update, two review authors extracted data and assessed trial quality. We analysed data using odds ratio (OR) and 95% confidence intervals (CIs). We applied fixed-effect or random-effects models.

Main results: 

We selected 11 trials reporting a total of 1486 participants. Six trials compared bypass surgery with percutaneous transluminal angioplasty (PTA), and one each with remote endarterectomy, thromboendarterectomy, thrombolysis, exercise, and spinal cord stimulation. The quality of the evidence for the most important outcomes of bypass surgery versus PTA was high except for clinical improvement and primary patency. We judged the quality of evidence for clinical improvement to be low, due to heterogeneity between the studies and the fact that this was a subjective outcome assessment and, therefore, at risk of detection bias. We judged the quality of evidence for primary patency to be moderate due heterogeneity between the studies. For the remaining comparisons, the evidence was limited. For several outcomes, the CIs were wide.

Comparing bypass surgery with PTA revealed a possible increase in early postinterventional non-thrombotic complications (OR 1.29, 95% CI 0.96 to 1.73; six studies; 1015 participants) with bypass surgery, but bypass surgery was associated with higher technical success rates (OR 2.26, 95% CI 1.49 to 3.44; five studies; 913 participants). Analyses by different clinical severity of disease (intermittent claudication (IC) or CLI) revealed that peri-interventional complications occurred more frequently in participants with CLI undergoing bypass surgery than PTA (OR 1.57, 95% CI 1.09 to 2.24). No differences in periprocedural mortality were identified (OR 1.67, 95% CI 0.66 to 4.19; five studies; 913 participants). The primary patency rate at one year was higher after bypass surgery than after PTA (OR 1.94, 95% CI 1.20 to 3.14; four studies; 300 participants), but this difference was not shown at four years (OR 1.15, 95% CI 0.74 to 1.78; two studies; 363 participants). No differences in clinical improvement (OR 0.65, 95% CI 0.03 to 14.52; two studies; 154 participants), amputation rates (OR 1.24, 95% CI 0.82 to 1.87; five studies; 752 participants), reintervention rates (OR 0.76, 95% CI 0.42 to 1.37; three studies; 256 participants), or mortality within the follow-up period (OR 0.94, 95% CI 0.71 to 1.25; five studies; 961 participants) between surgical and endovascular treatment were identified. No differences in subjective outcome parameters, indicated by quality of life and physical and psychosocial well-being, were reported. The hospital stay for the index procedure was reported to be longer in participants undergoing bypass surgery than in those treated with PTA.

In the single study (116 participants) comparing bypass surgery with remote endarterectomy of the superficial femoral artery, the frequency of early postinterventional non-thrombotic complications was similar in the treatment groups (OR 1.11, 95% CI 0.53 to 2.34). No mortality within 30 days of the index treatment or during stay in hospital in either group was recorded. No differences were identified in patency (OR 1.66, 95% CI 0.79 to 3.46), amputation (OR 1.70, 95% CI 0.27 to 10.58), and mortality rates within the follow-up period (OR 1.66, 95% CI 0.61 to 4.48). Information regarding clinical improvement was unavailable.

No differences in major complications (OR 0.66, 95% CI 0.34 to 1.31) or mortality (OR 2.09, 95% CI 0.67 to 6.44) within 30 days of treatment between surgery and thrombolysis (one study, 237 participants) for chronic lower limb ischaemia were identified. The amputation rate was lower after bypass surgery (OR 0.10, 95% CI 0.01 to 0.80). No differences in late mortality were found (OR 1.56, 95% CI 0.71 to 3.44). No data regarding patency rates and clinical improvement were reported.

Technical success resulting in blood flow restoration was higher after bypass surgery than thromboendarterectomy for aorto-iliac occlusive disease (one study, 43 participants) (OR 0.01, 95% CI 0 to 0.17). The periprocedural mortality (OR 0.33, 95% CI 0.01 to 8.65), follow-up mortality (OR 3.29, 95% CI 0.13 to 85.44), and amputation rates (OR 0.47, 95% CI 0.08 to 2.91) did not differ between treatments. Clinical improvement and patency rates were not reported.

Comparing surgery and exercise (one study, 75 participants) did not identify differences in early postinterventional complications (OR 7.45, 95% CI 0.40 to 137.76) and mortality (OR 1.55, 95% CI 0.06 to 39.31). The remaining primary outcomes were not reported. There was no difference in maximal walking time between exercise and surgery (1.66 min, 95% CI -1.23 to 4.55).

Regarding comparisons of bypass surgery with spinal cord stimulation for CLI, there was no difference in amputation rates after 12 months of follow-up (OR 4.00, 95% CI 0.25 to 63.95; one study, 12 participants). The remaining primary outcome parameters were not reported.

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