Effects of Three Months of Low Molecular Weight Heparin (dalteparin) Treatment After Bypass Surgery for Lower Limb Ischemia—A Randomised Placebo-controlled Double Blind Multicentre Trial

Antithrombotic treatment following revascularization for chronic limb-threatening ischaemia: a scientific statement of the European Society of Cardiology Working Group on Aorta and Peripheral Vascular Diseases and the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

Chronic limb-threatening ischaemia (CLTI) is defined as ischaemic rest pain, or non-healing ulceration, requiring endovascular or surgical lower limb revascularization (LLR). Lower limb revascularization in CLTI entails a high risk of major adverse limb events (MALE) and major adverse cardiovascular events (MACE). This scientific statement addresses this risk based on a systematic review. A structured literature search was performed, and articles were independently evaluated by two investigators. In total, 1678 articles were identified, of which 34 were included in the final analysis. Only three randomized controlled trials (RCTs) addressed antithrombotic therapy in CLTI following LLR. None of these demonstrated superiority of any antithrombotic regimen over the other. Eight RCTs investigated antithrombotic therapy following LLR in populations with peripheral arterial disease including CLTI subgroups and suggest a benefit of dual antiplatelet therapy on limb events. One large RCT demonstrated that dual pathway inhibition with aspirin and vascular-dose rivaroxaban reduced the risk of MALE, MACE, and unplanned target limb revascularization. Data from 22 observational studies suggest a benefit of dual antiplatelet therapy on overall survival and amputation-free survival after LLR as compared with single antiplatelet therapy. Intensified antithrombotic treatment should be proposed in patients with CLTI following LLR to reduce the risk of MALE and MACE. Randomized controlled trials on antithrombotic therapy in patients with CLTI following LLR are scarce. Dual pathway inhibition is the only regimen for which an RCT demonstrated a reduction of MALE and MACE following LLR. Dual antiplatelet therapy appears to be associated with a reduced risk of MALE in CLTI following LLR.

Medication adherence of patients with peripheral arterial disease to antithrombotic therapy: a systematic review

OBJECTIVES

Antithrombotic therapy (ATT) prevents atherothrombotic events (AE) in patients with peripheral arterial disease (PAD). However, the benefit may be compromised by poor medication adherence (MA). Therefore, our primary objective was the proportion of patients with PAD with poor MA in literature following patient-reported, pharmacy-reported or laboratory-reported outcome measurements. Poor MA is a combined outcome of primary non-adherence (inability to initiate a prescription), secondary non-adherence (incorrect daily intake) and non-persistence (discontinuation of daily intake).

DESIGN

Systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

DATA SOURCES

PubMed, EMBASE and Cochrane Library were searched from 2000 to June 2023.

ELIGIBILITY CRITERIA

Publications with a (sub)cohort of patients with PAD that reported on patients' MA to ATT were included.

DATA EXTRACTION AND SYNTHESIS

All articles were reviewed on eligibility and methodological quality by two independent researchers. The data were retrieved and collected in Review Manager Web and the percentages were calculated per subgroup. The risk of bias was assessed by using the Cochrane risk-of-bias tool for randomised controlled trials (RCT) and the methodological index for non-randomised studies score for non-RCTs.

RESULTS

We identified 274 potential records of which 10 studies (32 628 patients) were included. Six studies were RCTs and two prospective and two retrospective studies. Most studies scored a moderate risk of bias and had heterogeneous study designs. Poor MA rates ranged between 2% and 45%. Higher rates of poor MA were found in studies with longer follow-ups, pharmacy-reported outcome measurements and registry-based cohorts.

CONCLUSION

Heterogeneous study designs create a wide dispersion in the proportions. However, poor MA to ATT was found in approximately one-third of the patients with PAD and seemed to increase with longer therapy duration, which highlights the magnitude of this societal challenge. Enhancing patients' MA to ATT might be a key element in reducing the risk of AE, and therefore, more attention to MA in clinical and research settings is warranted.

PROSPERO REGISTRATION NUMBER

CRD42023431803.

Therapeutic anticoagulation after index peripheral endovascular intervention in patients with claudication

OBJECTIVE

Antiplatelet agents are commonly used after peripheral endovascular intervention (PVI). However, the effect of full-dose anticoagulation on outcomes after PVI is not well-established. We sought to investigate whether full-dose anticoagulation after PVI is associated with adverse events.

METHODS

We utilized the Vascular Quality Initiative to study patients undergoing index PVI for claudication (2010-2019), stratified by the presence or absence of an anticoagulant on discharge. The primary outcomes were 2-year patency, major adverse limb events (MALE), and mortality. We built a propensity score adjusting for comorbidities and employed inverse probability weighting to estimate the association of anticoagulation with outcomes.

RESULTS

We identified 26,240 patients; 9.1% were discharged on an anticoagulant. Patients receiving any anticoagulation had a significantly higher risk of mortality (adjusted hazard ratio [aHR], 1.61; 95% confidence interval [CI], 1.35-1.92), but not MALE, or patency loss. Patients receiving a vitamin K antagonist had a significantly higher risk of patency loss (aHR, 1.32; 95% CI, 1.09-1.60), MALE (aHR, 1.33; 95% CI, 1.13-1.57), and mortality (aHR, 1.46; 95% CI, 1.27-1.69). Patients on an oral Factor Xa inhibitors had a significantly lower risk of patency loss (aHR, 0.61; 95% CI, 0.41-0.93) but increased mortality (aHR, 1.51; 95% CI, 1.19-1.92).

CONCLUSIONS

Therapeutic anticoagulation after PVI is associated with higher risk of all-cause mortality. Although oral Factor Xa inhibitors are associated with decreased risk of patency loss, vitamin K antagonists are associated with higher risk of patency loss, MALE, and death. Further prospective studies are necessary to study the safety and efficacy of full-dose anticoagulation after PVI.

A Review of Antithrombotic Therapies for Patients with Chronic Peripheral Arterial Disease and after Revascularization

Peripheral arterial disease (PAD) represents a major health issue that significantly impacts patient's survival and quality of life. In addition to limb-related events, patients with PAD have an increased risk of myocardial infarction, stroke, and death. However, compared with coronary and cerebrovascular disease, studies addressing optimal risk reduction modalities including antithrombotic therapies in patients with PAD have been underrepresented in the literature. This publication serves as a narrative review of existing evidence on the effectiveness of antithrombotic therapy in patients with PAD. In patients with chronic stable PAD or post-revascularization, antithrombotic therapies including single or dual antiplatelet agents, anticoagulation, or a combination of these treatments have been shown to reduce cardiovascular and limb events. This narrative review provides a summary of the available literature on the management of patients with PAD, categorized into treatment strategies for chronic, post-endovascular treatment, and post-open surgical revascularization and to discuss the antithrombotic protocol utilized at our institution while providing a rational for our treatment algorithm.

Meta-Analysis of Anticoagulation Therapy for the Prevention of Cardiovascular Events in Patients With Peripheral Arterial Disease

Peripheral artery disease (PAD) remains a major cause of morbidity and future cardiovascular events despite advancement in the surgical interventions and optimal medical therapy. The aim of our study is to evaluate the efficacy and safety of anticoagulation (AC) therapy for reducing cardiovascular and limb events in patients with PAD. PUBMED, Medline, and Cochrane Library were searched through 2020 for randomized clinical trials comparing major adverse cardiovascular events (MACE) and risk of major bleeding (MB), between AC and standard of care (SOC) therapy, among patients with PAD. Meta-analysis was performed using weighted pooled absolute risk difference (RD) with 95% confidence interval (CI) and fixed effects model for overall and sub-groups of full dose (FD) and low dose (LD) AC therapies. Amongst 17,684 patients from 7 different studies, the addition of AC to SOC therapy was associated with MACE reduction (RD -0.022, 95% CI -0.033 to -0.012, p <0.001) and increased MB (RD 0.02, 95% CI 0.014 to 0.025, p <0.001). For FD, MACE reduction was (RD -0.021, 95% CI -0.042 to 0.001, p = 0.061) and MB (RD 0.036, 95% CI 0.025 to 0.047, p <0.001). For LD, MACE reduction was (RD -0.023, 95% CI -0.035 to -0.011, p <0.001) and MB (RD 0.011, 95% CI 0.005 to 0.017, p <0.001). In conclusion, addition of AC to the current SOC therapy can mitigate future MACE events in patients with PAD albeit at risk of increased bleeding. LD AC is associated with an efficacy/safety net benefit compared to FD AC therapy.

[Amputation as an anticipated consequence of peripheral artery disease and ways to improve the prognosis of limb salvage]

Peripheral artery disease is a common and acute social burden worldwide. The main method of treatment of PAD consists in open surgical or endovascular revascularization. However, despite steady growth of the number and quality of interventions, the incidence of lower-limb amputation still remains at a high level. Lower-limb amputation is a severe psychological blow for the patient and leads to significant deterioration of his or her quality of life, as well as has an extremely negative prognosis concerning the frequency of subsequent complications and survival. Consequences of amputations include not only severe disability but also an unfavourable prognosis of life, thus determining the necessity of adequate prevention of such events. Reconstructive and endovascular operations, as well as amputations are associated with a significant increase of the probability of the development of major adverse cardiovascular events, the frequency of repeat hospitalizations and, finally, the cost of treatment. Prescribing pathogenetically substantiated antithrombotic therapy is considered to be one of the methods to improve the results of surgical treatment and prognosis for the patient. Presented in the article is a literature review making it possible to assess the risks and consequences of amputations in patients with PAD, as well as to determine therapy capable of improving the prognosis.

Antithrombotic therapy for postinterventional management of peripheral arterial disease

PURPOSE

Evidence on the use of antithrombotic pharmacotherapy in patients undergoing revascularization of lower extremities for symptomatic peripheral arterial disease (PAD) is reviewed.

SUMMARY

Individuals with PAD can experience leg pain, intermittent claudication, critical limb ischemia, and acute limb ischemia. In such patients, revascularization may be indicated to improve the quality of life and to prevent amputations. Antithrombotic therapy is often intensified in the postrevascularization period to prevent restenosis of the index artery and to counteract the prothrombotic state induced by the intervention. Therapeutic modalities include dual antiplatelet therapy (DAPT), anticoagulation, a combination of antiplatelet and anticoagulation therapy, and addition of cilostazol to single antiplatelet therapy. Subgroup analyses of data from randomized clinical trials provided low-quality evidence for the use of DAPT in patients with a below-knee prosthetic bypass graft and anticoagulation for those with a venous bypass graft. Cilostazol, when added to aspirin therapy, has been shown to prevent index vessel reocclusion after an endovascular intervention in patients at low risk for thrombosis in several small randomized trials.

CONCLUSION

There is a considerable paucity of high-quality evidence on the optimal antithrombotic regimen for patients undergoing lower extremity revascularization, with no particular therapy shown to consistently improve patient outcomes. The decision to initiate intensified antithrombotic therapy should include a close examination of its risk-benefit profile. The demonstrated benefit of such treatment is restricted to the prevention of index artery reocclusion, while an increased risk of bleeding may lead to significant morbidity and mortality.

[Current concepts of anticoagulant and antiplatelet therapy in patients with vascular pathology]

The routine practice of a vascular surgeon is invariably associated with decreasing the risk of adverse cardiovascular events in patients presenting with either arterial or venous pathology. Antithrombotic therapy is one of the key approaches used to achieve this purpose. However, a wide variety of modern drugs inhibiting platelet aggregation and agents blocking the coagulation cascade, as well as their combinations makes the selection of the most appropriate treatment for a particular patient quite a difficult task. The choice should carefully be made taking into consideration the nosology, aetiology, accompanying diseases and therapy thereof, as well as the balance of the risk of ischaemic and haemorrhagic complications. Therefore, availability of modern antithrombotic drugs favourably contributing to a more personified approach to treatment is of utmost importance. Thus, for example, rivaroxaban, an anticoagulant belonging to the class of direct-acting oral factor Xa inhibitors, provides a possibility to select an optimal dosage and regimen for a particular patient with arterial or vascular pathology in practice of a cardiovascular surgeon.

Low molecular weight heparin for prevention of microvascular occlusion in digital replantation

BACKGROUND

The success of digital replantation is highly dependent on the patency of the repaired vessels after microvascular anastomosis. Antithrombotic agents are frequently used for preventing vascular occlusion. Low molecular weight heparin (LMWH) has been reported to be as effective as unfractionated heparin (UFH) in peripheral vascular surgery, but with fewer adverse effects. Its benefit in microvascular surgery such as digital replantation is unclear. This is an update of the review first published in 2013.

OBJECTIVES

To assess if treatment with subcutaneous LMWH improves the salvage rate of the digits in patients with digital replantation after traumatic amputation.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, AMED and CINAHL databases, and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers, to 17 March 2020. The authors searched PubMed, China National Knowledge Infrastructure (CNKI) and Chinese Electronic Periodical Services (CEPS) on 17 March 2020 and sought additional trials from reference lists of relevant publications.

SELECTION CRITERIA

We included randomised or quasi-randomised controlled trials comparing treatment with LMWH versus any other treatment in participants who received digital replantation following traumatic digital amputation.

DATA COLLECTION AND ANALYSIS

Two review authors (PL, CC) independently extracted data and assessed the risk of bias of the included trials using Cochrane's 'Risk of bias' tool. Disagreements were resolved by discussion. We assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included two new randomised trials in this update, bringing the total number of included trials to four. They included a total of 258 participants, with at least 273 digits, from hospitals in China. Three studies compared LMWH versus UFH, and one compared LMWH versus no LMWH. The mean age of participants ranged from 24.5 to 37.6 years. In the studies reporting the sex of participants, there were a total of 145 men and 59 women. The certainty of the evidence was downgraded to low or very low because all studies were at high risk of performance or reporting bias (or both) and there was imprecision in the results due to the small numbers of participants. The three studies comparing LMWH versus UFH reported the success rate of replantation using different units of analysis (participant or digit), so we were unable to combine data from all three studies (one study reported results for both participants and digits). No evidence of a benefit in success of replantation was seen in the LMWH group when compared with UFH, regardless of whether the outcomes were reported by number of participants (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.87 to 1.10; 130 participants, 2 studies; very low-certainty evidence); or by number of digits (RR 0.97, 95% CI 0.90 to 1.04; 200 digits, 2 studies; low-certainty evidence). No studies reported the incidence of compromised microcirculation requiring surgical or non-surgical therapy, or any systemic/other causes of microvascular insufficiency. There was no evidence of a clear difference between the LMWH and UFH groups in occurrence of arterial occlusion (RR 1.08, 95% CI 0.16 to 7.10; 54 participants, 1 study; very low-certainty evidence) or venous occlusion (RR 0.81, 95% CI 0.20 to 3.27; 54 participants, 1 study; very low-certainty evidence). Two studies reported adverse effects. The LMWH and UFH groups showed no evidence of a difference in wound bleeding (RR 0.53, 95% CI 0.23 to 1.23; 130 participants, 2 studies; low-certainty evidence), haematuria (RR 0.43, 95% CI 0.09 to 2.11; 130 participants, 2 studies; very low-certainty evidence), ecchymoses (RR 0.82, 95% CI 0.21 to 3.19; 130 participants, 2 studies; very low-certainty evidence), epistaxis (RR 0.27, 95% CI 0.03 to 2.32; 130 participants, 2 studies; very low-certainty evidence), gingival bleeding (RR 0.18, 95% CI 0.02 to 1.43; 130 participants, 2 studies; very low-certainty evidence), and faecal occult blood (RR 0.27, 95% CI 0.03 to 2.31; 130 participants, 2 studies; very low-certainty evidence). We could not pool data on coagulation abnormalities as varying definitions and tests were used in the three studies. One study compared LMWH versus no LMWH. The success rate of replantation, when analysed by digits, was reported as 91.2% success in the LMWH group and 82.1% in the control group (RR 1.11, 95% CI 0.93 to 1.33; 73 digits, 1 study; very low-certainty evidence). Compromised microcirculation requiring surgical re-exploration, analysed by digits, was 11.8% in the LMWH group and 17.9% in the control group (RR 0.86, 95% CI 0.21 to 3.58; 73 digits, 1 study; very low-certainty evidence). Compromised microcirculation requiring incision occurred in five out of 34 digits (14.7%) in the LMWH group and eight out of 39 digits (20.5%) in the control group (RR 0.72, 95% CI 0.26 to 1.98; 73 digits; very low-certainty evidence). Microvascular insufficiency due to arterial occlusion, analysed by digits, was 11.8% in the LMWH group and 17.9% in the control group (RR 0.66, 95% CI 0.21 to 2.05; 73 digits, 1 study; very low-certainty evidence), and venous occlusion was 14.7% in the LMWH group and 20.5% in the control (RR 0.72, 95% CI 0.26 to 1.98; 73 digits, 1 study; very low-certainty evidence). The study did not report complications or adverse effects.

AUTHORS' CONCLUSIONS

There is currently low to very low-certainty evidence, based on four RCTs, suggesting no evidence of a benefit from LMWH when compared to UFH on the success rates of replantation or affect microvascular insufficiency due to vessel occlusion (analysed by digit or participant). LMWH had similar success rates of replantation; and the incidence rate of venous and arterial microvascular insufficiency showed no evidence of a difference between groups when LMWH was compared to no LMWH (analysed by digit). Similar rates of complications and adverse effects were seen between UFH and LMWH. There was insufficient evidence to draw conclusions on any effect on coagulation when comparing LMWH to UFH or no LMWH. The certainty of the evidence was downgraded due to performance and reporting bias, as well as imprecision in the results. Further adequately powered studies are warranted to provide high-certainty evidence.

Peripheral arterial disease: Scoping review of patient-centred outcomes

Peripheral arterial disease (PAD) impairs patients' quality of life (QOL), walking and ulcer healing, increasing patient pain, costs, and risks of amputation or mortality. A literature appraisal described PAD treatment capacity to improve validated patient-centred outcomes in controlled clinical studies. The PUBMED database was searched from 1 January 1970 to 21 June 2018, for original and derivative controlled clinical trial references addressing MeSH terms for 'ischemia' AND 'leg ulcer'. Non-ischemic ulcer treatment references were excluded. Frequencies of improved (P < .05) outcomes were reported. Eighty-eight studies on 4153 patients were summarized. Walking, pain or QOL improved mainly for interventions administered before PAD became severe. Amputation incidence, pain and ulcer healing were more frequently reported in those with severe PAD. Independent of PAD severity, patients experienced more likely improved walking, QOL, or pain reduction in response to structured walking interventions or those increasing calf muscle activity. Those with more severe PAD were more likely to report amputation reduction, mainly in response to invasive interventions. Those with PAD experienced more consistently improved patient-centred outcomes if they received multidisciplinary PAD management with supervised walking or calf muscle activity, with more likely amputation risk reduced for those with more severe PAD.

Antiplatelet agents for preventing thrombosis after peripheral arterial bypass surgery

BACKGROUND

Peripheral arterial disease (PAD) may cause occlusions (blockages) in the main arteries of lower limbs. One treatment option is bypass surgery using autologous (the patient's own tissue) vein graft or prosthetic (artificial) graft. A number of factors influence occlusion rates in these patients, including the material used. To prevent graft occlusion patients are usually treated with antiplatelet, antithrombotic drugs, or a combination of both.

OBJECTIVES

To determine the effects of antiplatelet agents for the prevention of thrombosis in people with lower limb atherosclerosis who were undergoing femoropopliteal or femorodistal bypass grafting. Outcomes included the overall success of therapy (graft patency and limb salvage rates) and complications of treatment.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched June 2014) and the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 5). We sought additional trials through screening the reference lists of relevant papers.

SELECTION CRITERIA

Two review authors, RB and AL, independently reviewed studies found in the search and evaluated them based on the inclusion and exclusion criteria, resolving disagreements through discussion.

DATA COLLECTION AND ANALYSIS

RB and AL independently extracted details of the selected studies for the update. We compared the treatment and control groups for important prognostic factors and differences described. If any data were unavailable, we sought further information from study authors. We synthesised data by comparing group results. We addressed unit of analysis issues by subgroup analysis.

MAIN RESULTS

We include 16 studies with 5683 randomised participants. Nine different treatment groups were evaluated: aspirin (ASA) or aspirin and dipyridamole (ASA/DIP) versus placebo or nothing (six studies); ASA or ASA/DIP versus pentoxifylline (two studies); ASA/DIP versus indobufen (one study); ASA or ASA/DIP versus vitamin K antagonists (two studies); ASA/DIP versus low molecular weight heparin (one study); ticlopidine versus placebo (one study); ASA versus prostaglandin E1 (one study); ASA versus naftidrofuryl (one study); and clopidogrel and ASA versus ASA alone (one study). The treatment comparisons were evaluated separately, and, where possible, we performed subgroup analysis for venous grafts and prosthetic grafts and at different follow-up time points. The quality of evidence was low to moderate as many of the treatment comparisons had very few studies to contribute data, several of the included studies had unit of analysis issues, the treatment dosages varied between studies, and data for many outcomes important to this review were not given in any of the studies, or differed greatly between studies. Overall study quality was moderate, with the largest problem being that the majority of studies did not describe their methods of randomisation, allocation concealment or blinding of outcome assessors, leading to risk ratings of 'unclear'. The other main issue with study quality was studies not blinding participants or personnel.The treatment comparison with the most number of included studies, which allowed for robust conclusions, was that of aspirin (ASA) or ASA and dipyridamole (ASA/DIP) versus placebo or nothing, covered by six studies. For this treatment group, there was improved graft patency in the ASA or ASA/DIP treatment group, odds ratio (OR) 0.42 (95% confidence interval (CI) 0.22 to 0.83; P = 0.01; 952 participants). This effect was not seen for venous grafts alone at any of the time points, but was observed for all time points in prosthetic grafts, including the final time point of 12 months (OR 0.19, 95% CI 0.10 to 0.36; P < 0.00001; 222 participants). Only a single study evaluated secondary patency, for which there was no difference between treatment groups. For the comparison ASA or ASA/DIP versus placebo or nothing there was no difference for any of the side effects, including general, gastrointestinal, bleeding and wound/graft infection. Amputations, cardiovascular events and mortality were also similar between the treatment groups. The comparison of ASA or ASA/DIP versus vitamin K antagonists included two studies, one of which was very large, with over 2000 participants. There were no differences between treatment for primary graft patency at three, six, 12 or 24 months, and there was also no evidence of a difference for limb amputation, cardiovascular events or mortality. One large study (851 participants) evaluated clopidogrel and ASA versus ASA alone, and for all grafts there was no evidence of a difference of primary patency at 24 months. There was evidence of increased total bleeding in the clopidogrel and ASA group (OR 2.65, 95% CI 1.69 to 4.15) from an increase in mild (OR 2.34, 95% CI 1.37 to 4.00), and moderate bleeding (OR 4.13, 95% CI 1.37 to 12.45), but no difference in severe or fatal bleeding. There was no difference between the treatment groups for limb amputation or mortality. For the remaining treatment comparisons there is not currently enough evidence to draw any robust conclusions about the efficacy or safety of the treatment on graft patency after peripheral bypass.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin or with aspirin plus dipyridamole had a beneficial effect on primary patency of peripheral bypass grafts compared to placebo or no treatment. This effect was not evident when evaluating venous grafts alone, but antiplatelet therapy did have a beneficial effect on patency in those who had prosthetic grafts. There was no evidence of differences in side effects (including general, gastrointestinal, bleeding or infection), amputation, cardiovascular events or mortality between the treatment groups. However, the number of participants included in this analysis might be too small to detect a statistically significant effect for side effects, amputation, cardiovascular morbidity or mortality. We found no difference in primary graft patency when aspirin or aspirin with dipyridamole was compared to a vitamin K antagonist or when clopidogrel with aspirin was compared to aspirin alone. However, there was evidence of increase bleeding in the clopidogrel with aspirin group for the latter comparison. The remaining six treatment comparisons did not include enough data to draw any robust conclusions about their efficacy or safety at this time.

Low molecular weight heparin for prevention of microvascular occlusion in digital replantation

BACKGROUND

The success of digital replantation is highly dependent on the patency of the repaired vessels after microvascular anastomosis. Antithrombotic agents are frequently used for preventing vascular occlusion. Low molecular weight heparin (LMWH) has been reported to be as effective as unfractionated heparin (UFH) in peripheral vascular surgery, but with fewer adverse effects. Its benefit in microvascular surgery such as digital replantation is unclear.

OBJECTIVES

To assess whether subcutaneous LMWH treatment improves the salvage rate of the digits in patients with digital replantation after traumatic amputation.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator (TSC) searched the Specialised Register (October 2012), CENTRAL (2012, Issue 10) and trials databases. In addition, the authors searched PubMed, CNKI (China National Knowledge Infrastructure) and CEPS (Chinese Electronic Periodical Services), and sought additional trials from reference lists of relevant publications.

SELECTION CRITERIA

We selected randomised or quasi-randomised controlled trials of LMWH in patients who received digital replantation.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of the included trials. Disagreements were resolved by discussion.

MAIN RESULTS

Two randomised trials involving 114 patients with at least 122 replanted digits met the inclusion criteria and were included. Both trials compared the efficacy and safety of LMWH with UFH. We found no trials comparing LMWH with placebo or other anticoagulants. The data from the two included studies were insufficient for meta-analysis. The overall success rate of replantation did not differ between the LMWH and UFH groups, 92.3% versus 89.2% in one trial (risk ratio (RR) 1.03; 95% confidence interval (CI) 0.87 to 1.22) and 94.3% versus 94.15% in the other trial (RR 1.00; 95% CI 0.89 to 1.13). The incidence of both postoperative arterial and venous insufficiency were reported in one trial and did not significantly differ between the LMWH and UFH groups (RR 1.08; 95% CI 0.16 to 7.10 and RR 0.81; 95% CI 0.20 to 3.27, respectively). Direct and indirect causes of microvascular insufficiency were not reported in the trials. Different methods were used to monitor the adverse effects related to anticoagulation in the two trials. Bleeding tendency was monitored for the LMWH and UFH groups in one trial and was reported by the incidence of wound haemorrhage (11.5% versus 17.9%; RR 0.65; 95% CI 0.17 to 2.44), ecchymoses (3.8% versus 10.7%; RR 0.36; 95% CI 0.04 to 3.24), haematuria (3.8% versus 7.1%; RR 0.54; 95% CI 0.05 to 5.59), nasal bleeding (0% versus 7.1%; RR 0.21; 95% CI 0.01 to 4.28), gingival bleeding (0% versus 10.7%; RR 0.15, 95% CI 0.01 to 2.83) and faecal occult blood (0% versus 3.6%; RR 0.36; 95% CI 0.02 to 8.42). The bleeding tendency was increased in the UFH group but this was not statistically significant. This trial also monitored coagulability changes using parameters such as antithrombin activity, factor Xa activity, bleeding time, clotting time and activated partial thromboplastin time (aPTT). No comparison was made between the LMWH and UFH groups but all data consistently showed that coagulability was reduced more in the UFH group than in the LMWH group. The other trial reported a postoperative decrease in platelet count in the UFH group (preoperative 278.4 ± 18.7 x 10(9)/L, postoperative 194.3 ± 26.5 x 10(9)/L; P < 0.05) but not in the LMWH group (preoperative 260.8 ± 32.5 x 10(9)/L, postoperative 252.4 ± 29.1 x 10(9)/L; P > 0.05).

AUTHORS' CONCLUSIONS

Current limited evidence based on two small-scaled low-to-medium quality randomised trials found no differences in the success rate of replantation between LMWH and UFH, but a lower risk of postoperative bleeding and hypocoagulability after the use of LMWH. Further well-designed and adequately powered clinical trials are warranted.

Chapter VI: Follow-up after revascularisation

Structured follow-up after revascularisation for chronic critical limb ischaemia (CLI) aims at sustained treatment success and continued best patient care. Thereby, efforts need to address three fundamental domains: (A) best medical therapy, both to protect the arterial reconstruction locally and to reduce atherosclerotic burden systemically; (B) surveillance of the arterial reconstruction; and (C) timely initiation of repeat interventions. As most CLI patients are elderly and frail, sustained resolution of CLI and preserved ambulatory capacity may decide over independent living and overall prognosis. Despite this importance, previous guidelines have largely ignored follow-up after CLI; arguably because of a striking lack of evidence and because of a widespread assumption that, in the context of CLI, efficacy of initial revascularisation will determine prognosis during the short remaining life expectancy. This chapter of the current CLI guidelines aims to challenge this disposition and to recommend evidentially best clinical practice by critically appraising available evidence in all of the above domains, including antiplatelet and antithrombotic therapy, clinical surveillance, use of duplex ultrasound, and indications for and preferred type of repeat interventions for failing and failed reconstructions. However, as corresponding studies are rarely performed among CLI patients specifically, evidence has to be consulted that derives from expanded patient populations. Therefore, most recommendations are based on extrapolations or subgroup analyses, which leads to an almost systematic degradation of their strength. Endovascular reconstruction and surgical bypass are considered separately, as are specific contexts such as diabetes or renal failure; and critical issues are highlighted throughout to inform future studies.

Antithrombotic agents for preventing thrombosis after infrainguinal arterial bypass surgery

BACKGROUND

Peripheral arterial disease (PAD) is frequently treated by either an infrainguinal autologous (using the patient's own veins) or synthetic graft bypass. The rate of occlusion of the graft after one year is between 12% and 60%. To prevent occlusion, patients are treated with an antiplatelet or antithrombotic drug, or a combination of both. Little is known about which drug is optimal to prevent infrainguinal graft occlusion. This is an update of a Cochrane review first published in 2003.

OBJECTIVES

To evaluate whether antithrombotic treatment improves graft patency, limb salvage and survival in patients with chronic PAD undergoing infrainguinal bypass surgery.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched August 2010) and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 3).

SELECTION CRITERIA

Randomised, controlled trials; two review authors independently assessed the methodological quality of each trial using a standardised checklist.

DATA COLLECTION AND ANALYSIS

Data collected included patient details, inclusion and exclusion criteria, type of graft, antithrombotic therapy, outcomes, and side effects.

MAIN RESULTS

A total of 14 trials were included in this review; 4970 patient results were analysed. Four trials evaluating vitamin K antagonists (VKA) versus no VKA suggested that oral anticoagulation may favour autologous venous, but not artificial, graft patency as well as limb salvage and survival. Two other studies comparing VKA with aspirin (ASA) or aspirin and dipyridamole provided evidence to support a positive effect of VKA on the patency of venous but not artificial grafts. Three trials comparing low molecular weight heparin (LMWH) to unfractionated heparin (UFH) failed to demonstrate a significant difference on patency. One trial comparing LMWH with placebo found no significant improvement in graft patency over the first postoperative year in a population receiving aspirin. One trial showed an advantage for LMWH versus aspirin and dipyridamol at one year for patients undergoing limb salvage procedures. Perioperative administration of ancrod showed no greater benefit when compared to unfractionated heparin. Dextran 70 showed similar graft patency rates to LMWH but a significantly higher proportion of patients developed heart failure with dextran.

AUTHORS' CONCLUSIONS

Patients undergoing infrainguinal venous graft are more likely to benefit from treatment with VKA than platelet inhibitors. Patients receiving an artificial graft benefit from platelet inhibitors (aspirin). However, the evidence is not conclusive. Randomised controlled trials with larger patient numbers are needed in the future to compare antithrombotic therapies with either placebo or antiplatelet therapies.

Antiplatelet agents for preventing thrombosis after peripheral arterial bypass surgery

BACKGROUND

Peripheral arterial disease (PAD) may cause occlusions (blockages) in the main arteries of lower limbs. One treatment option is bypass surgery using autologous (the patient's own tissue) vein graft or artificial graft. A number of factors influence occlusion rates, including the material used. To prevent graft occlusion patients are usually treated with antiplatelet, antithrombotic drugs, or a combination of both.

OBJECTIVES

To evaluate whether antiplatelet treatment in patients with symptomatic PAD undergoing infrainguinal bypass surgery improves graft patency, limb salvage and survival.

SEARCH STRATEGY

The authors searched the Cochrane Peripheral Vascular Diseases Group Specialised Register (January 2008) and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 4). Additional trials were sought through reference lists of papers and proceedings from the vascular surgical society meetings.

SELECTION CRITERIA

For this update the methodological quality of each original trial was assessed independently by review authors (JB, HM, AW) with emphasis on concealment of allocation.

DATA COLLECTION AND ANALYSIS

Details of the selected studies were extracted independently by JB and HM for the update. The treatment and control groups were compared for important prognostic factors and differences described. If any data were unavailable, further information was sought from authors. Data were synthesised by comparing group results. Unit of analysis issues were addressed by subgroup analysis.

MAIN RESULTS

The administration of a variety of platelet inhibitors resulted in improved venous and artificial graft patency when compared to no treatment. However, analysing patients for graft-type indicated that those patients receiving a prosthetic graft were more likely to benefit from administration of platelet inhibitors than patients treated with venous grafts.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin had a slight beneficial effect on the patency of peripheral bypass grafts but seemed to have an inferior effect on venous graft patency compared with artificial grafts. The effect of aspirin on cardiovascular outcomes and survival was small and not statistically significant. This might be due to the fact that the majority of patients receiving a peripheral graft have an advanced stage of PAD with critical ischaemia. They are usually seriously ill as a result of cardiovascular disease and have high mortality rates, of 20% per year. Additionally, the number of patients included in this analysis might be too small to reach a statistically significant effect for mortality and cardiovascular morbidity.