Antiplatelet and anticoagulant drugs for prevention of restenosis/reocclusion following peripheral endovascular treatment

Antithrombotic regimens in females with symptomatic lower extremity peripheral arterial disease: protocol for a systematic review and meta-analysis

INTRODUCTION

Patients with peripheral arterial disease (PAD) are at increased risk for systemic arterial thromboembolic events. Females represent a unique subset of patients with PAD, who differ from males in important ways: they have smaller diameter vessels, undergo lower extremity bypass less frequently and experience higher rates of graft occlusion, amputation and mortality than males. Females also trend towards higher rates of major coronary events and cardiovascular mortality. Current guidelines recommend monoantiplatelet therapy (MAPT) for secondary prevention in patients with symptomatic PAD. However, indications for more intensive antithrombotic therapy in this cohort-especially among females who are frequently under-represented in randomised controlled trials (RCTs)-remain unclear. As newer antithrombotic therapies emerge, some RCTs have demonstrated differential effects in females versus males. A systematic review is needed to quantify the rates of arterial thromboembolic and bleeding events with different antithrombotic regimens in females with symptomatic PAD.

METHODS AND ANALYSIS

We will search MEDLINE, Embase and the Cochrane Central Register of Controlled trials for published RCTs that include females with symptomatic PAD and compare full dose anticoagulation±antiplatelet therapy, dual pathway inhibition or dual antiplatelet therapy with MAPT. Title, abstract and full-text screening will be conducted in duplicate by three reviewers. Authors will be contacted to obtain sex-stratified outcomes as needed. Risk of bias will be assessed using the Cochrane Risk of Bias tool. Data will be extracted by independent reviewers and confirmed by a second reviewer. Quantitative synthesis will be conducted using Review Manager (RevMan) V.5 for applicable outcomes data. Planned subgroup analysis by PAD severity, vascular intervention and indication for antithrombotics will be conducted where data permits.

ETHICS AND DISSEMINATION

Ethics approval is waived as the study does not involve primary data collection. This review will be submitted for publication in a peer-reviewed journal and for presentation at national and international scientific meetings.

TRIAL REGISTRATION NUMBER

This protocol was registered with the PROSPERO International Prospective Register of Systematic Reviews (ID# CRD42020196933).

Clopidogrel plus aspirin versus aspirin alone for preventing cardiovascular events

BACKGROUND

Aspirin is the prophylactic antiplatelet drug of choice for people with cardiovascular disease. Adding a second antiplatelet drug to aspirin may produce additional benefit for people at high risk and people with established cardiovascular disease. This is an update to a previously published review from 2011.

OBJECTIVES

To review the benefit and harm of adding clopidogrel to aspirin therapy for preventing cardiovascular events in people who have coronary disease, ischaemic cerebrovascular disease, peripheral arterial disease, or were at high risk of atherothrombotic disease, but did not have a coronary stent.

SEARCH METHODS

We updated the searches of CENTRAL (2017, Issue 6), MEDLINE (Ovid, 1946 to 4 July 2017) and Embase (Ovid, 1947 to 3 July 2017) on 4 July 2017. We also searched ClinicalTrials.gov and the WHO ICTRP portal, and handsearched reference lists. We applied no language restrictions.

SELECTION CRITERIA

We included all randomised controlled trials comparing over 30 days use of aspirin plus clopidogrel with aspirin plus placebo or aspirin alone in people with coronary disease, ischaemic cerebrovascular disease, peripheral arterial disease, or at high risk of atherothrombotic disease. We excluded studies including only people with coronary drug-eluting stent (DES) or non-DES, or both.

DATA COLLECTION AND ANALYSIS

We collected data on mortality from cardiovascular causes, all-cause mortality, fatal and non-fatal myocardial infarction, fatal and non-fatal ischaemic stroke, major and minor bleeding. The overall treatment effect was estimated by the pooled risk ratio (RR) with 95% confidence interval (CI), using a fixed-effect model (Mantel-Haenszel); we used a random-effects model in cases of moderate or severe heterogeneity (I2 ≥ 30%). We assessed the quality of the evidence using the GRADE approach. We used GRADE profiler (GRADE Pro) to import data from Review Manager to create a 'Summary of findings' table.

MAIN RESULTS

The search identified 13 studies in addition to the two studies in the previous version of our systematic review. Overall, we included data from 15 trials with 33,970 people. We completed a 'Risk of bias' assessment for all studies. The risk of bias was low in four trials because they were at low risk of bias for all key domains (random sequence generation, allocation concealment, blinding, selective outcome reporting and incomplete outcome data), even if some of them were funded by the pharmaceutical industry.Analysis showed no difference in the effectiveness of aspirin plus clopidogrel in preventing cardiovascular mortality (RR 0.98, 95% CI 0.88 to 1.10; participants = 31,903; studies = 7; moderate quality evidence), and no evidence of a difference in all-cause mortality (RR 1.05, 95% CI 0.87 to 1.25; participants = 32,908; studies = 9; low quality evidence).There was a lower risk of fatal and non-fatal myocardial infarction with clopidogrel plus aspirin compared with aspirin plus placebo or aspirin alone (RR 0.78, 95% CI 0.69 to 0.90; participants = 16,175; studies = 6; moderate quality evidence). There was a reduction in the risk of fatal and non-fatal ischaemic stroke (RR 0.73, 95% CI 0.59 to 0.91; participants = 4006; studies = 5; moderate quality evidence).However, there was a higher risk of major bleeding with clopidogrel plus aspirin compared with aspirin plus placebo or aspirin alone (RR 1.44, 95% CI 1.25 to 1.64; participants = 33,300; studies = 10; moderate quality evidence) and of minor bleeding (RR 2.03, 95% CI 1.75 to 2.36; participants = 14,731; studies = 8; moderate quality evidence).Overall, we would expect 13 myocardial infarctions and 23 ischaemic strokes be prevented for every 1000 patients treated with the combination in a median follow-up period of 12 months, but 9 major bleeds and 33 minor bleeds would be caused during a median follow-up period of 10.5 and 6 months, respectively.

AUTHORS' CONCLUSIONS

The available evidence demonstrates that the use of clopidogrel plus aspirin in people at high risk of cardiovascular disease and people with established cardiovascular disease without a coronary stent is associated with a reduction in the risk of myocardial infarction and ischaemic stroke, and an increased risk of major and minor bleeding compared with aspirin alone. According to GRADE criteria, the quality of evidence was moderate for all outcomes except all-cause mortality (low quality evidence) and adverse events (very low quality evidence).

Peripheral interventions and antiplatelet therapy: Role in current practice

Peripheral arterial disease (PAD) is a common disorder associated with a high risk of cardiovascular mortality and continues to be under-recognized. The major risk factors for PAD are similar to those for coronary and cerebrovascular disease. Management includes exercise program, pharmacologic therapy and revascularization including endovascular and surgical approach. The optimal revascularization strategy, endovascular or surgical intervention, is often debated due to the paucity of head to head randomized controlled studies. Despite significant advances in endovascular interventions resulting in increased utilization over surgical bypass, significant challenges still remain. Platelet activation and aggregation after percutaneous transluminal angioplasty of atherosclerotic arteries are important risk factors for re-occlusion/restenosis and life-threatening thrombosis following endovascular procedures. Antiplatelet agents are commonly prescribed to reduce the risk of myocardial infarction, stroke and death from cardiovascular causes in patients with PAD. Despite an abundance of data demonstrating efficacy of antiplatelet therapy in coronary artery disease and cerebrovascular disease, there is a paucity of clinical information, clinical guidelines and randomized controlled studies in the PAD population. Hence, data on antiplatelet therapy in coronary interventions is frequently extrapolated to peripheral interventions. The aim of this review article is to elucidate the current data on revascularization and the role and duration of antiplatelet and anticoagulant therapy in re-vascularized lower limb PAD patients.

Tong-xin-luo capsule for patients with coronary heart disease after percutaneous coronary intervention

BACKGROUND

Percutaneous coronary intervention (PCI) is a standard treatment for coronary heart disease (CHD). Restenosis, defined as a 50% reduction in luminal diameter at six months after PCI, indicates a need for revascularisation. Restenosis has proven to be a major drawback to PCI. Tong-xin-luo is one of the prophylactic strategies for cardiovascular events in patients after PCI that is widely used in China, but its efficacy and safety have not been systematically evaluated.

OBJECTIVES

To systematically assess the efficacy and safety of Tong-xin-luo capsules in preventing cardiovascular events after PCI in patients with CHD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials in The Cochrane Library, MEDLINE (OVID), EMBASE (OVID), WanFang, Chinese Biomedical Database, Chinese Medical Current Contents, and China National Knowledge Infrastructure from their inception to June 2014. We also searched other resources, including ongoing trials and research registries. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials of participants with CHD after PCI were included. Participants in the intervention group received Tong-xin-luo capsules for at least three months.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. Any disagreements were resolved by discussion with a third review author. The primary outcomes included occurrence of angiographic restenosis and adverse events; the secondary outcomes included myocardial infarction, heart failure, angina, all cause mortality, mortality due to any cardiovascular event, use of revascularisation, patient acceptability, quality of life and cost-effectiveness. Dichotomous data were measured with risk ratios (RRs) with 95% confidence intervals (CIs).

MAIN RESULTS

Sixteen studies involving 1063 participants were identified. The risk of bias for fifteen studies was high and along with imprecision and possible publication bias, this lowered our confidence in the results. There was low quality evidence that Tong-xi-luo reduced the rates of angiographic restenosis (RR 0.16, 95% CI 0.07 to 0.34), myocardial infarction (RR 0.32, 95% CI 0.16 to 0.66), heart failure (RR 0.26, 95% CI 0.11 to 0.62), and use of revascularisation (RR 0.26, 95% CI 0.15 to 0.45). There was very low quality evidence for the effect of Tong-xin-luo on all-cause mortality (RR 0.38, 95% CI 0.06 to 2.56), angina (RR 0.24, 95% CI 0.17 to 0.34) and death due to any cardiovascular event (RR 0.31, 95% CI 0.08 to 1.12). Adverse events were seldom reported, and included gastrointestinal reactions and nausea.

AUTHORS' CONCLUSIONS

The addition of Tong-xin-luo to conventional Western medicine may possibly prevent restenosis and recurrence of cardiovascular events in patients with CHD after PCI. However, the data are limited by publication bias and high risk of bias for included studies. Further high-quality trials are required to evaluate the potential effects of this intervention.

VA Vascular Injury Study (VAVIS): VA-DoD extremity injury outcomes collaboration

BACKGROUND

Limb injuries comprise 50-60% of U.S. Service member's casualties of wars in Afghanistan and Iraq. Combat-related vascular injuries are present in 12% of this cohort, a rate 5 times higher than in prior wars. Improvements in medical and surgical trauma care, including initial in-theatre limb salvage approaches (IILS) have resulted in improved survival and fewer amputations, however, the long-term outcomes such as morbidity, functional decline, and risk for late amputation of salvaged limbs using current process of care have not been studied. The long-term care of these injured warfighters poses a significant challenge to the Department of Defense (DoD) and Department of Veterans Affairs (VA).

METHODS/DESIGN

The VA Vascular Injury Study (VAVIS): VA-DoD Extremity Injury Outcomes Collaborative, funded by the VA, Health Services Research and Development Service, is a longitudinal cohort study of Veterans with vascular extremity injuries. Enrollment will begin April, 2015 and continue for 3 years. Individuals with a validated extremity vascular injury in the Department of Defense Trauma Registry will be contacted and will complete a set of validated demographic, social, behavioral, and functional status measures during interview and online/ mailed survey. Primary outcome measures will: 1) Compare injury, demographic and geospatial characteristics of patients with IILS and identify late vascular surgery related limb complications and health care utilization in Veterans receiving VA vs. non-VA care, 2) Characterize the preventive services received by individuals with vascular repair and related outcomes, and 3) Describe patient-reported functional outcomes in Veterans with traumatic vascular limb injuries.

DISCUSSION

This study will provide key information about the current process of care for Active Duty Service members and Veterans with polytrauma/vascular injuries at risk for persistent morbidity and late amputation. The results of this study will be the first step for clinicians in VA and military settings to generate evidence-based treatment and care approaches to these injuries. It will identify areas where rehabilitation medicine and vascular specialty care or telehealth options are needed to allow for better planning, resource utilization, and improved DoD-to-VA care transitions.

Systematic reviews and meta-analyses for more profitable strategies in peripheral artery disease

In the peripheral arteries, a thrombus superimposed on atherosclerosis contributes to the progression of peripheral artery disease (PAD), producing intermittent claudication (IC), ischemic necrosis, and, potentially, loss of the limb. PAD with IC is often undiagnosed and, in turn, undertreated. The low percentage of diagnosis (∼30%) in this setting of PAD is of particular concern because of the potential worsening of PAD (amputation) and the high risk of adverse vascular outcomes (vascular death, coronary artery disease, stroke). A Medline literature search of the highest-quality systematic reviews and meta-analyses of randomized controlled trials documents that, due to risk of bias, imprecision, and indirectness, the overall quality of the evidence concerning diagnostic tools and antithrombotic interventions in PAD is generally low. Areas of research emerge from the information collected. Appropriate treatments for PAD patients will only derive from ad-hoc studies. Innovative imaging techniques are needed to identify PAD subjects at the highest vascular risk. Whether IC unresponsive to physical exercise and smoking cessation identifies those with a heritable predisposition to more severe vascular events deserves to be addressed. Devising ways to improve prevention of vascular events in patients with PAD implies a co-ordinated approach in vascular medicine.

Twelve-month results of a randomized trial comparing mono with dual antiplatelet therapy in endovascularly treated patients with peripheral artery disease

PURPOSE

To present the 12-month results of a trial investigating the effects of dual antiplatelet therapy on target lesion revascularization (TLR) after balloon angioplasty ± stenting in the femoropopliteal segment.

METHODS

A prospective, randomized, single-center, double-blinded and placebo-controlled clinical trial randomly assigned 40 patients to receive pre- and postinterventional therapy with aspirin and clopidogrel. Another 40 patients received the same doses of aspirin and placebo instead of clopidogrel. Clopidogrel and placebo were stopped after 6 months, and patients remained on aspirin only. At 12 months after the intervention, 36 clopidogrel patients and 37 placebo patients were reevaluated.

RESULTS

At 6 months, clopidogrel patients had significantly lower rates of TLR compared to placebo patients [2 (5%) vs. 8 (20%), p=0.04]. After stopping clopidogrel/placebo after 6 months, there was no significant difference in TLR at 12 months after treatment [9 (25%) clopidogrel vs. 12 (32.4%) placebo, p=0.35]. Mortality was 0 vs. 1 in the placebo group at 6 months (p=0.32) and 0 vs. 3 at 12 months (p=0.08).

CONCLUSION

In contrast to the first report of a reduction in the TLR at 6 months, this advantage of dual antiplatelet therapy does not persist after stopping clopidogrel. Prolonged dual therapy (>6 months) should be considered in patients who are at high risk for restenosis.

Cilostazol is associated with improved outcomes after peripheral endovascular interventions

OBJECTIVE

Although cilostazol is commonly used as an adjunct after peripheral vascular interventions, its efficacy remains uncertain. We assessed the effect of cilostazol on outcomes after peripheral vascular interventions using meta-analytic techniques.

METHODS

We searched MEDLINE (1946-2012), Cochrane CENTRAL (1996-2012), and trial registries for studies comparing cilostazol in combination with antiplatelet therapy to antiplatelet therapy alone after peripheral vascular interventions. Treatment effects were reported as pooled risk/hazard ratio (HR) with random-effects models.

RESULTS

Two randomized trials and four retrospective cohorts involving 1522 patients met inclusion criteria. Across studies, mean age ranged from 65 to 76 years, and the majority of patients were male (64%-83%); mean follow-up ranged from 18 to 37 months. Most interventions were in the femoropopliteal segment, and overall, 68% of patients had stents placed. Pooled estimates demonstrated that the addition of cilostazol was associated with decreased restenosis (relative risk [RR], 0.71; 95% confidence interval [CI], 0.60-0.84; P < .001), improved amputation-free survival (HR, 0.63; 95% CI, 0.47-0.85; P = .002), improved limb salvage (HR, 0.42; 95% CI, 0.27-0.66; P < .001), and improved freedom from target lesion revascularization (RR, 1.36; 95% CI, 1.14-1.61; P < .001). There was no significant reduction in mortality among those receiving cilostazol (RR, 0.73; 95% CI, 0.45-1.19; P = .21).

CONCLUSIONS

The addition of cilostazol to antiplatelet therapy after peripheral vascular interventions is associated with a reduced risk of restenosis, amputation, and target lesion revascularization in our meta-analysis of six studies. Consideration of cilostazol as a medical adjunct after peripheral vascular interventions is warranted, presuming these findings are broadly generalizable.

A review of the role of anticoagulation in the treatment of peripheral arterial disease

Peripheral arterial disease (PAD) is a major medical/surgical problem associated with high risk for coronary heart disease (CHD). Anticoagulation plays a significant role in the management of the PAD patient. However, evidence-based medicine supports only select anticoagulants, mainly antiplatelet agents. The available anticoagulant classes, their individual medications, and the mechanisms of action are described. Dextran 40, platelet glycoprotein (GP) IIb/IIIa receptor antagonists, direct thrombin (factor IIa, FIIa) inhibitors, and factor Xa (FXa) inhibitors do not, at this juncture, appear to have a significant role to play in the PAD patient. Aspirin has been used in PAD patients for a few decades, as has warfarin, but the role of warfarin is very limited. An attempt has been made to place each medication and its function in context all the way to the present with oral direct thrombin (FIIa) and FXa inhibitors described. These inhibitors may ultimately play an, as yet, undefined role in PAD. Specific use of anticoagulants in PAD patients is described and aspirin still stands out as a fundamental therapy. The thienopyridines, especially clopidogrel, have their established place and there is some evidence for benefit from the use of clopidogrel in dual therapy with aspirin. Dipyridamole, especially with aspirin as dual therapy, and cilostazol also have their evidence-based niches. The main role played by warfarin is for the patient with a vein graft in the arterial circulation. Heparin retains significant procedural importance. For now, Class I, Level of Evidence A center around aspirin for the PAD patient with clopidogrel, an alternative agent.

Critical limb ischemia: advanced medical therapy

Systemic atherosclerosis and its risk factors are present in the majority of patients with critical limb ischemia. Aggressive medical therapy is an immediate and necessary part of the work-up and management of these patients and will involve a multidisciplinary approach. Risk stratification based on a patient's current clinical cardiovascular condition is important in determining the most appropriate and safe intervention and will allow both the patient and physician to make an informed decision regarding risk- and cost-benefits of treatment.

Antiplatelet and anticoagulant drugs for prevention of restenosis/reocclusion following peripheral endovascular treatment

BACKGROUND

Peripheral arterial disease (PAD) is frequently treated by balloon angioplasty. Restenosis/reocclusion of the dilated segments occurs often, depending on length of occlusion, lower leg outflow, stage of disease and presence of cardiovascular risk factors. To prevent reocclusion, patients are treated with antithrombotic agents. This is an update of a review first published in 2005.

OBJECTIVES

To determine whether any antithrombotic drug is more effective in preventing restenosis or reocclusion after peripheral endovascular treatment, compared to another antithrombotic drug, no treatment, placebo or other vasoactive drugs.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched 14 February 2012) and CENTRAL (2012, Issue 1).

SELECTION CRITERIA

We selected randomised controlled trials (RCTs). Participants were patients with symptomatic PAD treated by endovascular revascularisation of the pelvic or femoropopliteal arteries. Interventions were anticoagulant, antiplatelet or other vasoactive drug therapy compared with no treatment, placebo or any other vasoactive drug. Clinical endpoints were reocclusion, restenosis, amputation, death, myocardial infarction, stroke, major bleeding and other side effects, such as minor bleeding, puncture site bleeding, gastrointestinal side effects and haematoma.

DATA COLLECTION AND ANALYSIS

We independently extracted and assessed details of the number of randomised patients, treatment, study design, patient characteristics and risk of bias. Analysis was based on intention-to-treat data. To examine the effects of outcomes such as reocclusion, restenosis, amputation and major bleeding, we computed odds ratios (OR) with 95% confidence intervals (CI) using a fixed-effect model.

MAIN RESULTS

Twenty-two trials with a total of 3529 patients are included (14 in the original review and a further eight in this update). For the majority of comparisons, only one trial was available so results were rarely combined in meta-analyses. Individual trials were generally small and risk of bias was often unclear due to limitations in reporting. Three trials reported on drug versus placebo/control; results were consistently available for a maximum follow-up of only six months. At six months post intervention, a statistically significant reduction in reocclusion was found for high-dose acetylsalicylic acid (ASA) combined with dipyridamole (DIP) (OR 0.40, 95% CI 0.19 to 0.84), but not for low-dose ASA combined with DIP (OR 0.69, 95% CI 0.44 to 1.10; P = 0.12) nor in major amputations for lipo-ecraprost (OR 0.89, 95% CI 0.44 to 1.80). The remaining trials compared different drugs; results were more consistently available for a longer period of 12 months. At 12 months post intervention, no statistically significant difference in reocclusion/restenosis was detected for any of the following comparisons: high-dose ASA versus low-dose ASA (OR 0.98, 95% CI 0.64 to 1.48; P = 0.91), ASA/DIP versus vitamin K antagonists (VKA) (OR 0.65, 95% CI 0.40 to 1.06; P = 0.08), clopidogrel and aspirin versus low molecular weight heparin (LMWH) plus warfarin (OR 0.31, 95% CI 0.06 to 1.68; P = 0.18), suloctidil versus VKA: reocclusion (OR 0.59, 95% CI 0.20 to 1.76; P = 0.34), restenosis (OR 1.87, 95% CI 0.66 to 5.31; P = 0.24) and ticlopidine versus VKA (OR 0.71, 95% CI 0.37 to 1.36; P = 0.30). Treatment with cilostazol resulted in statistically significantly fewer reocclusions than ticlopidine (OR 0.32, 95% CI 0.13 to 0.76; P = 0.01). Compared with aspirin alone, LMWH plus aspirin significantly decreased occlusion/restenosis (by up to 85%) in patients with critical limb ischaemia (OR 0.15, 95% CI 0.06 to 0.42; P = 0.0003) but not in patients with intermittent claudication (OR 1.73, 95% CI 0.97 to 3.08; P = 0.06) and batroxobin plus aspirin reduced restenosis in diabetic patients (OR 0.28, 95% CI 0.13 to 0.60). Data on bleeding and other potential gastrointestinal side effects were not consistently reported, although there was some evidence that high-dose ASA increased gastrointestinal side effects compared with low-dose ASA, that clopidogrel and aspirin resulted in fewer major bleeding episodes compared with LMWH plus warfarin, and that abciximab resulted in more severe bleeding episodes.

AUTHORS' CONCLUSIONS

There is limited evidence suggesting that restenosis/reocclusion at six months following peripheral endovascular treatment is reduced by use of antiplatelet drugs compared with placebo/control, but associated information on bleeding and gastrointestinal side effects is lacking. There is also some evidence of variation in effect according to different drugs with cilostazol reducing reocclusion/restenosis at 12 months compared with ticlopidine and both LMWH and batroxobin combined with aspirin appearing beneficial compared with aspirin alone. However, available trials are generally small and of variable quality and side effects of drugs are not consistently addressed. Further good quality, large-scale RCTs, stratified by severity of disease, are required.

Management of peripheral arterial interventions with mono or dual antiplatelet therapy--the MIRROR study: a randomised and double-blinded clinical trial

OBJECTIVES

To investigate the influence of dual antiplatelet therapy vs. aspirin alone on local platelet activation and clinical endpoints in patients with PAD treated with endovascular therapy.

METHODS

Patients received either 500 mg aspirin and 300 mg clopidogrel before intervention followed by a daily dose of 100 mg aspirin and 75 mg clopidogrel for 6 months, or the same doses of aspirin plus placebo instead of clopidogrel. Primary endpoints were local concentrations of platelet activation markers β-thromboglobulin and CD40L, and the rate of patient's resistant to clopidogrel. Secondary endpoints included the clinical development 6 months after the intervention.

RESULTS

Eighty patients, 40 in each group, were enrolled. The median peri-interventional concentration of β-TG was 224.5 vs. 365.5 (P = 0.03) in the clopidogrel and placebo group. The concentration of CD40L was 127 and 206.5 (P = 0.05). Thirty per cent of patients who had received clopidogrel were resistant. Two clopidogrel and eight placebo patients required TLR (P = 0.04). The clopidogrel patients who needed revascularisation were both resistant to clopidogrel. Minor bleeding complications occurred in one clopidogrel and two placebo patients.

CONCLUSION

Dual antiplatetet therapy reduces peri-interventional platelet activation and improves functional outcome without higher bleeding complications. An individual tailored dual antiplatelet therapy seems desirable for endovascularly treated patients with PAD.

Clopidogrel use before renal artery angioplasty with/without stent placement resulted in tertiary procedure risk reduction

OBJECTIVE

Contrary to coronary artery literature, the effect of preprocedural clopidogrel on renal artery restenosis (RAR) has not been characterized. This study was designed to evaluate the effect of preprocedural clopidogrel on target vessel revascularization (TVR), reintervention, and restenosis for patients who underwent recurrent renal artery angioplasty.

METHODS

A retrospective analysis of patients treated for RAR in a single tertiary center from January 1999 to December 2009 was conducted. Patients were divided into preadmission use of (1) clopidogrel or (2) aspirin only (acetylsalicylic acid [ASA]) for the initial procedure. TVR was defined as occurrence of a tertiary procedure for symptomatic RAR. Rate of freedom from event (ie, tertiary restenosis and TVR) was analyzed using Kaplan-Meier method.

RESULTS

Eighty-eight interventions were performed on 77 patients with RAR; 66% were females with average (mean ± SEM) age and body mass index of 68.8 ± 1.1 and 28.6 ± 0.8, respectively. Comorbidities included 96% chronic hypertension, 33% diabetes, 76% hyperlipidemia, 20% renal insufficiency, 39% tobacco use, 58% coronary artery disease, and 51% peripheral vascular disease. Clopidogrel use increased significantly during the index procedure from admission 35.2% to discharge 97.7% (P < .001, McNemar test). There was a trend toward risk reduction of a tertiary intervention (23%) for patients admitted on clopidogrel compared with ASA (P = .052). Likewise, there was a trend (P = .051) toward increased freedom from a tertiary intervention, with cumulative freedom at 8 years 93.5% for clopidogrel vs 61% for ASA. No differences were found for restenosis.

CONCLUSIONS

The use of preprocedural clopidogrel was associated with a possible risk reduction of TVR reintervention, but this finding needs to be validated in randomized clinical trial.

Antithrombotic therapy in peripheral artery disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This guideline focuses on antithrombotic drug therapies for primary and secondary prevention of cardiovascular disease as well as for the relief of lower-extremity symptoms and critical ischemia in persons with peripheral arterial disease (PAD).

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

The most important of our 20 recommendations are as follows. In patients aged ≥ 50 years with asymptomatic PAD or asymptomatic carotid stenosis, we suggest aspirin (75-100 mg/d) over no therapy (Grade 2B) for the primary prevention of cardiovascular events. For secondary prevention of cardiovascular disease in patients with symptomatic PAD (including patients before and after peripheral arterial bypass surgery or percutaneous transluminal angioplasty), we recommend long-term aspirin (75-100 mg/d) or clopidogrel (75 mg/d) (Grade 1A). We recommend against the use of warfarin plus aspirin in patients with symptomatic PAD (Grade 1B). For patients undergoing peripheral artery percutaneous transluminal angioplasty with stenting, we suggest single rather than dual antiplatelet therapy (Grade 2C). For patients with refractory claudication despite exercise therapy and smoking cessation, we suggest addition of cilostazol (100 mg bid) to aspirin (75-100 mg/d) or clopidogrel (75 mg/d) (Grade 2C). In patients with critical limb ischemia and rest pain unable to undergo revascularization, we suggest the use of prostanoids (Grade 2C). In patients with acute limb ischemia due to acute thrombosis or embolism, we recommend surgery over peripheral arterial thrombolysis (Grade 1B).

CONCLUSIONS

Recommendations continue to favor single antiplatelet therapy for primary and secondary prevention of cardiovascular events in most patients with asymptomatic PAD, symptomatic PAD, and asymptomatic carotid stenosis. Additional therapies for relief of limb symptoms should be considered only after exercise therapy, smoking cessation, and evaluation for peripheral artery revascularization.

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.

Current approach to the diagnosis and treatment of femoral-popliteal arterial disease. A systematic review

Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis affecting 5 million adults in the United States, with an age-adjusted prevalence of 4% to 15% and increasing up to 30% with age and the presence of cardiovascular risk factors. In this article we focus on lower extremity PAD and specifically on the superficial femoral and proximal popliteal artery (SFPA), which are the most common anatomic locations of lower extremity atherosclerosis. We summarize current evidence and perform a systematic review on the diagnostic evaluation as well as the medical, endovascular and surgical management of SFPA disease.

Clopidogrel plus aspirin versus aspirin alone for preventing cardiovascular disease

BACKGROUND

Aspirin is the prophylactic antiplatelet drug of choice for people with cardiovascular disease. Adding a second antiplatelet drug to aspirin may produce additional benefit for those at high risk and those with established cardiovascular disease.

OBJECTIVES

To quantify the benefit and harm of adding clopidogrel to standard long-term aspirin therapy for preventing cardiovascular events in people at high risk of cardiovascular disease and those with established cardiovascular disease.

SEARCH STRATEGY

The searches have been updated: CENTRAL (Issue 3 2009), MEDLINE (2002 to September 2009) and EMBASE (2002 to September 2009).

SELECTION CRITERIA

All randomized controlled trials comparing long term use of aspirin plus clopidogrel with aspirin plus placebo or aspirin alone in patients with coronary disease, ischemic cerebrovascular disease, peripheral arterial disease, or at high risk of atherothrombotic disease were included.

DATA COLLECTION AND ANALYSIS

Data on mortality, non-fatal myocardial infarction, non-fatal stroke, unstable angina, heart failure, revascularizations, major and minor bleeding, and all adverse events were collected. The overall treatment effect was estimated by the pooled odds ratio (OR) with 95% confidence interval (CI) using a fixed-effect model (Mantel-Haenszel).

MAIN RESULTS

No new studies were identified from the updated searches. A total of two RCTs were found: the CHARISMA and the CURE study. The CURE study enrolled only patients with a recent non-ST segment elevation acute coronary syndrome. The use of clopidogrel plus aspirin, compared with placebo plus aspirin, was associated with a lower risk of cardiovascular events (OR: 0.87, 95% CI 0.81 to 0.94; P<0.01) and a higher risk of major bleeding (OR 1.34, 95% CI 1.14 to 1.57; P<0.01). Overall, we would expect 13 cardiovascular events to be prevented for every 1000 patients treated with the combination, but 6 major bleeds would be caused. In the CURE trial, for every 1000 people treated, 23 events would be avoided and 10 major bleeds would be caused. In the CHARISMA trial, for every 1000 people treated, 5 cardiovascular events would be avoided and 3 major bleeds would be caused.

AUTHORS' CONCLUSIONS

The available evidence demonstrates that the use of clopidogrel plus aspirin is associated with a reduction in the risk of cardiovascular events and an increased risk of bleeding compared with aspirin alone. Only in patients with acute non-ST coronary syndrome benefits outweigh harms.

Results of the randomized, placebo-controlled clopidogrel and acetylsalicylic acid in bypass surgery for peripheral arterial disease (CASPAR) trial

OBJECTIVE

Dual antiplatelet therapy with clopidogrel plus acetylsalicylic acid (ASA) is superior to ASA alone in patients with acute coronary syndromes and in those undergoing percutaneous coronary intervention. We sought to determine whether clopidogrel plus ASA conferred benefit on limb outcomes over ASA alone in patients undergoing below-knee bypass grafting.

METHODS

Patients undergoing unilateral, below-knee bypass graft for atherosclerotic peripheral arterial disease (PAD) were enrolled 2 to 4 days after surgery and were randomly assigned to clopidogrel 75 mg/day plus ASA 75 to 100 mg/day or placebo plus ASA 75 to 100 mg/day for 6 to 24 months. The primary efficacy endpoint was a composite of index-graft occlusion or revascularization, above-ankle amputation of the affected limb, or death. The primary safety endpoint was severe bleeding (Global Utilization of Streptokinase and Tissue plasminogen activator for Occluded coronary arteries [GUSTO] classification).

RESULTS

In the overall population, the primary endpoint occurred in 149 of 425 patients in the clopidogrel group vs 151 of 426 patients in the placebo (plus ASA) group (hazard ratio [HR], 0.98; 95% confidence interval [CI], 0.78-1.23). In a prespecified subgroup analysis, the primary endpoint was significantly reduced by clopidogrel in prosthetic graft patients (HR, 0.65; 95% CI, 0.45-0.95; P = .025) but not in venous graft patients (HR, 1.25; 95% CI, 0.94-1.67, not significant [NS]). A significant statistical interaction between treatment effect and graft type was observed (P(interaction) = .008). Although total bleeds were more frequent with clopidogrel, there was no significant difference between the rates of severe bleeding in the clopidogrel and placebo (plus ASA) groups (2.1% vs 1.2%).

CONCLUSION

The combination of clopidogrel plus ASA did not improve limb or systemic outcomes in the overall population of PAD patients requiring below-knee bypass grafting. Subgroup analysis suggests that clopidogrel plus ASA confers benefit in patients receiving prosthetic grafts without significantly increasing major bleeding risk.

[Medicinal therapy for interventional surgery of the peripheral vascular system]

The aim of medicinal treatment, during and after femoral and crural interventions is to prevent early or late onset arterial thrombosis of the treated vascular segments. Therefore, unfractionated heparin is administered during the intervention by an intra-arterial or intravenous approach. To avoid late onset thrombosis, administration of platelet function inhibitors is recommended. However, valid data are only available for acetylsalicylic acid (ASA). Therefore, ASA is recommended for long term medication. In several cardiological studies on stent implantation in coronary vessels the combination of ASA and clopidogrel for dual platelet inhibition has been proven to be effective. These results have been transferred to antithrombotic therapy of the lower extremities despite the lack of dedicated studies. There is no evidence for the use of vitamin K antagonists after peripheral interventions.

Effect of dipyridamole plus aspirin on hemodialysis graft patency

BACKGROUND

Arteriovenous graft stenosis leading to thrombosis is a major cause of complications in patients undergoing hemodialysis. Procedural interventions may restore patency but are costly. Although there is no proven pharmacologic therapy, dipyridamole may be promising because of its known vascular antiproliferative activity.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of extended-release dipyridamole, at a dose of 200 mg, and aspirin, at a dose of 25 mg, given twice daily after the placement of a new arteriovenous graft until the primary outcome, loss of primary unassisted patency (i.e., patency without thrombosis or requirement for intervention), was reached. Secondary outcomes were cumulative graft failure and death. Primary and secondary outcomes were analyzed with the use of a Cox proportional-hazards regression with adjustment for prespecified covariates.

RESULTS

At 13 centers in the United States, 649 patients were randomly assigned to receive dipyridamole plus aspirin (321 patients) or placebo (328 patients) over a period of 4.5 years, with 6 additional months of follow-up. The incidence of primary unassisted patency at 1 year was 23% (95% confidence interval [CI], 18 to 28) in the placebo group and 28% (95% CI, 23 to 34) in the dipyridamole-aspirin group, an absolute difference of 5 percentage points. Treatment with dipyridamole plus aspirin significantly prolonged the duration of primary unassisted patency (hazard ratio, 0.82; 95% CI, 0.68 to 0.98; P=0.03) and inhibited stenosis. The incidences of cumulative graft failure, death, the composite of graft failure or death, and serious adverse events (including bleeding) did not differ significantly between study groups.

CONCLUSIONS

Treatment with dipyridamole plus aspirin had a significant but modest effect in reducing the risk of stenosis and improving the duration of primary unassisted patency of newly created grafts. (ClinicalTrials.gov number, NCT00067119.)

Clopidogrel plus aspirin versus aspirin alone for preventing cardiovascular disease

BACKGROUND

Aspirin is the prophylactic antiplatelet drug of choice for people with cardiovascular disease. However, protection with antiplatelet therapy in people with a high risk of cardiovascular disease is unsatisfactory in absolute terms. Adding a second antiplatelet drug to aspirin may produce additional benefit for those at high risk and those with established cardiovascular disease.

OBJECTIVES

To quantify the effects (both benefit and harm) of adding clopidogrel to standard long-term aspirin therapy for preventing cardiovascular events in people at high risk of cardiovascular disease and those with established cardiovascular disease.

SEARCH STRATEGY

CENTRAL (Issue 2 2006), MEDLINE (2002 to May 2006) and EMBASE (2002 to May 2006) were searched. Online registers of ongoing trials and reference lists from original articles and reviews were checked.

SELECTION CRITERIA

All randomized controlled trials comparing long term (>30 days) use of aspirin plus clopidogrel with aspirin plus placebo or aspirin alone in patients with coronary disease, ischemic cerebrovascular disease, peripheral arterial disease, or at high risk of atherothrombotic disease (with data for at least one of the outcomes) were included.

DATA COLLECTION AND ANALYSIS

Data were collected on the following outcomes and analysed where appropriate: mortality (from myocardial infarction, stroke, cardiovascular causes, all-causes), non-fatal myocardial infarction, non-fatal stroke, unstable angina, heart failure, revascularizations, major and minor bleeding, and all adverse events. Quantitative analysis of outcome was based on an intention-to-treat principle. The overall treatment effect was estimated by the pooled odds ratio (OR) with 95% confidence interval (CI) using a fixed-effect model (Mantel-Haenszel).

MAIN RESULTS

Two RCTs were found. Patients enrolled in the CHARISMA study were at high risk for cardiovascular events, either with or without an established cardiovascular disease. Patients enrolled in the CURE study had a recent non-ST segment elevation acute coronary syndrome. The use of clopidogrel plus aspirin, compared with placebo plus aspirin, was associated with a lower risk of cardiovascular events (OR: 0.87, 95% CI 0.81 to 0.94; P<0.01) and a higher risk of major bleeding (OR 1.34, 95% CI 1.14 to 1.57; P<0.01). Overall, we would expect 13 cardiovascular events to be prevented for every 1000 patients treated with the combination, but 6 major bleeds would be caused. Treatment effects differed in the two trials: the CURE trial, confined to people with acute non-ST segment coronary syndromes, showed definite evidence of benefit from treatment. For every 1000 people treated for an average of 9 months, 23 events would be avoided and 10 major bleeds would be caused. In the CHARISMA trial that randomized people at high cardiovascular risk defined either in terms of pre-existing cardiovascular diseases or risk factors, the effects of treatment were less marked and were consistent with the play of chance. For every 1000 people treated for an average of 28 months, 5 cardiovascular events would be avoided and 3 major bleeds would be caused.

AUTHORS' CONCLUSIONS

The available evidence demonstrates that the use of clopidogrel plus aspirin is associated with a reduction in the risk of cardiovascular events compared with aspirin alone in patients with acute non-ST coronary syndrome. In patients at high risk of cardiovascular disease but not presenting acutely, there is only weak evidence of benefit and hazards of treatment almost match any benefit obtained.

Critical limb ischemia

Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease (PAD). Without timely recognition, appropriate diagnosis, and revascularization, patients with CLI are at risk for amputation or potentially fatal complications. The past decade has seen substantial growth in endovascular CLI therapies and options now exist for treating long-segment lower-extremity arterial occlusive disease, but surgical bypass may yield more durable results. Patients who are younger, more active, and at low risk for surgery may have better outcomes with an operation. Surgical treatment is also indicated for failures of endovascular therapy, which may include early technical failures or later occlusion after placement of stents or other interventions.

Pharmacotherapy Before and After Revascularization: Anticoagulation, Antiplatelet Agents, and Statins

Proper medical management may enhance perioperative and long-term outcomes for patients with peripheral arterial disease (PAD). For patients with PAD, aspirin and statin drugs remain the mainstay of medical management, based on results from multiple randomized clinical trials that have demonstrated improvements in long-term survival and a decrease in cardiovascular events with these agents. There may additional, unintended positive consequences of treatment with statin drugs, including potential improvements in symptoms of claudication and enhanced graft patency after infrainguinal bypass. For patients undergoing surgical or endovascular revascularization, aspirin remains the standard of care for antithrombotic therapy. Beyond this, use of warfarin should be reserved for patients with high-risk surgical bypass grafts to prolong graft patency, because it carries a significant risk of bleeding complications. The utility of clopidogrel after surgical and endovascular infrainguinal revascularization remains undefined but warrants additional study. At this time the only clear indication for clopidogrel in patients with infrainguinal arterial occlusive disease is for PAD patients who are intolerant of aspirin or have a history of coronary artery stenting within the past 6 months. Proper adjunctive pharmacotherapy for the patient with PAD has the potential to improve symptoms, graft patency, and survival in this challenging subset of patients.