Antiplatelet therapy and other interventions after revascularisation procedures in patients with peripheral arterial disease: a meta-analysis

2D perfusion angiography as quantitative method to evaluate iloprost effect on foot circulation

Background: Two-dimensional (2D) perfusion angiography is useful for the evaluation of foot perfusion in patients with critical limb-threatening ischemia (CLTI). Iloprost is a synthetic prostacyclin analogue presenting vasodilating properties. Aim of this study was to demonstrate the utility of 2D perfusion angiography as quantitative method to evaluate iloprost effect on foot circulation. Patients and methods: Between January 2020 and June 2020 25 patients with CLTI underwent below-the-knee (BTK) endovascular revascularization, intra-arterial administration of iloprost, and assessment of foot perfusion by 2D perfusion angiography. Iloprost was administered as an intra-arterial bolus of 3 μg over 1-3 minutes immediately after BTK revascularization. The 2D perfusion angiography was performed in a standardized manner with a 5-F catheter placed into the popliteal artery. A wide region of interest (ROI) was identified to assess the foot perfusion. Time-density curves were calculated by the perfusion software. Changes of the overall time-density curves before and after the administration of iloprost were evaluated. Results: Endovascular revascularization was successful in all cases. The mean reduction of systolic pressure value after iloprost administration was 23.1 mmHg. Eight patients (32%) experienced a minor complication (6 cutaneous rush, 2 symptomatic hypotension >40 mmHg). In 20 patients the time-density curves under ROI increased after the intra-arterial administration of iloprost (+31.6%, range from +4.9% to +78.7%). Five patients had no modification or a slight decrease of foot perfusion after iloprost administration (non-responders patients). Conclusions: Patients undergoing intra-arterial administration of iloprost accounted for a not negligible rate of minor complications. 2D perfusion angiography was valuable as quantitative method to evaluate the iloprost effect on foot circulation. This technique could be useful to classify the patients in responders or non-responders to iloprost therapy.

Umbrella review and meta-analysis of antiplatelet therapy for peripheral artery disease

Background

The literature on antiplatelet therapy for peripheral artery disease has historically been summarized inconsistently, leading to conflict between international guidelines. An umbrella review and meta-analysis was performed to summarize the literature, allow assessment of competing safety risks and clinical benefits, and identify weak areas for future research.

Methods

MEDLINE, Embase, DARE, PROSPERO and Cochrane databases were searched from inception until January 2019. All meta-analyses of antiplatelet therapy in peripheral artery disease were included. Quality was assessed using AMSTAR scores, and GRADE analysis was used to quantify the strength of evidence. Data were pooled using random-effects models.

Results

Twenty-eight meta-analyses were included. Thirty-three clinical outcomes and 41 antiplatelet comparisons in 72 181 patients were analysed. High-quality evidence showed that antiplatelet monotherapy reduced non-fatal strokes (3 (95 per cent c.i. 0 to 6) fewer per 1000 patients), In symptomatic patients, it reduced cardiovascular deaths (8 (0 to 16) fewer per 1000 patients), but increased the risk of major bleeding (7 (3 to 14) more events per 1000). In asymptomatic patients, monotherapy reduced non-fatal strokes (5 (0 to 8) fewer per 1000), but had no other clinical benefit. Dual antiplatelet therapy caused more major bleeding after intervention than monotherapy (37 (8 to 102) more events per 1000), with very low-quality evidence of improved endovascular patency (risk ratio 4·00, 95 per cent c.i. 0·91 to 17·68).

Conclusion

Antiplatelet monotherapy has minimal clinical benefit for asymptomatic peripheral artery disease, and limited benefit for symptomatic disease, with a clear risk of major bleeding. There is a lack of evidence to guide antiplatelet prescribing after peripheral endovascular intervention.

Antiplatelet therapy for tibial balloon angioplasty: A clinical perspective

Percutaneous transluminal tibial balloon angioplasty has an important role in the therapeutic approach of critical limb ischaemia. Despite a growing number of patients with critical limb ischaemia, there are no trials to guide the pharmacologic approach post intervention. Guidelines pertaining to the antiplatelet therapy post percutaneous transluminal tibial balloon angioplasty have not been developed. In addition, critical limb ischaemia patients have multiple comorbidities and a higher risk of bleeding. To examine the shortest duration of antiplatelet therapy post percutaneous transluminal tibial balloon angioplasty, we reviewed the preclinical data used to develop the standards for the current angioplasty technique.

Rationale and design for the Vascular Outcomes study of ASA along with rivaroxaban in endovascular or surgical limb revascularization for peripheral artery disease (VOYAGER PAD)

BACKGROUND

Patients with peripheral artery disease (PAD) undergoing a lower-extremity revascularization are at heightened risk for ischemic cardiac and limb events. Although intensification of antithrombotic therapy after revascularization has demonstrated benefit in coronary disease populations, this approach has not been well studied or shown consistent benefit in PAD. Recent trial evidence demonstrated that a treatment strategy of rivaroxaban added to background antiplatelet therapy reduced ischemic risk in patients following recent acute coronary syndromes, as well as in patients with stable atherosclerotic vascular disease. Whether these benefits extend to the population of patients with symptomatic lower-extremity PAD undergoing revascularization is the objective of the VOYAGER PAD trial.

STUDY DESIGN

VOYAGER PAD is an international randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of rivaroxaban in symptomatic PAD patients undergoing a peripheral surgical and/or endovascular revascularization. Patients are randomized in a 1:1 ratio to either rivaroxaban 2.5 mg twice daily or placebo, on a background of low-dose aspirin (100 mg daily). In addition, the use of a limited course of P2Y₁₂ inhibition is allowed at the discretion of the site investigator. The primary efficacy end point is a novel composite of myocardial infarction, ischemic stroke, cardiovascular death, acute limb ischemia, and major amputation of vascular etiology. The primary safety end point is major bleeding according to the Thrombolysis in Myocardial Infarction definition. Enrolment began in August 2015 and will complete randomization of at least 6,500 patients by January 2018. This event-driven trial is expected to observe outcomes over a mean patient follow-up of 30 months.

CONCLUSIONS

VOYAGER PAD is evaluating the efficacy of rivaroxaban added to background antiplatelet therapy to reduce major cardiovascular and limb ischemic vascular outcomes in the high-risk population of PAD patients undergoing peripheral revascularization.

Clopidogrel and 1-Year Freedom From Amputation After Endovascular Lower Extremity Revascularization in the Medicare Population

Objective:

To evaluate freedom from amputation in patients identified utilizing clopidogrel following their lower extremity endovascular revascularization (LER).

Methods:

Patients, 65 years of age and older, undergoing LER were identified from Medicare Provider Analysis and Review and Carrier files utilizing International Classification of Diseases diagnosis and Current Procedural Terminology codes. Postprocedural use of clopidogrel was identified using the National Drug Code directory. Outcomes were evaluated.

Results:

A total of 14 353 patients were identified: 5697 (39.7%) with claudication, 1467 (10.2%) with rest pain, and 7189 (50.1%) with ulceration/tissue loss. In all, 5416 (37.7%) patients were identified using clopidogrel after LER. Overall, patients initiated on clopidogrel had lower amputation rates at 30 days (10.34% vs 14.09%; P < .0001), 90 days (14.05% vs 18.71%; P < .0001), and 1 year (19.68% vs 24.06%; P < .0001).

Conclusion:

Utilization of clopidogrel after LER was associated with lower rates of amputation, yet only 38% of the Medicare population was identified as using clopidogrel. Patients with ulceration and tissue loss benefited the most with significantly greater freedom from amputation and overall survival.

Role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia: therapeutic potential for prevention of vein graft failure?

The saphenous vein remains the most widely used conduit for peripheral and coronary revascularization despite a high rate of vein graft failure. The most common cause of vein graft failure is intimal hyperplasia. No agents have been proven to be successful for the prevention of intimal hyperplasia in human subjects. The renin-angiotensin system is essential in the regulation of vascular tone and blood pressure in physiologic conditions. However, this system mediates cardiovascular remodeling in pathophysiologic states. Angiotensin II is becoming increasingly recognized as a potential mediator of intimal hyperplasia. Drugs modulating the renin-angiotensin system include angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. These drugs are powerful inhibitors of atherosclerosis and cardiovascular remodeling, and they are first-line agents for management of several medical conditions based on class I evidence that they delay progression of cardiovascular disease and improve survival. Several experimental models have demonstrated that these agents are capable of inhibiting intimal hyperplasia. However, there are no data supporting their role in prevention of intimal hyperplasia in patients with vein grafts. This review summarizes the physiology of the renin-angiotensin system, the role of angiotensin II in the pathogenesis of cardiovascular remodeling, the medical indications for these agents, and the experimental data supporting an important role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia.

Gene therapy in the treatment of peripheral arterial disease

BACKGROUND

Peripheral arterial disease remains a significant global health burden despite revolutionary improvements in endovascular techniques over the past decade. The durability of intervention for critical limb ischaemia is poor, and the condition is associated with high morbidity and mortality rates. To address this deficiency, alternative therapeutic options are being explored. Advances in the fields of gene therapy and therapeutic angiogenesis have led to these being advocated as potential future treatments.

METHODS

Relevant medical literature from PubMed, Embase, the Cochrane Library and Google Scholar from the inception of these databases to June 2011 was reviewed.

RESULTS

Encouraging outcomes in preclinical trials using a variety of proangiogenic growth factors have led to numerous efficacy and safety studies. However, no clinical study has shown significant benefit for gene therapy over placebo.

CONCLUSION

Identifying the optimal site for gene delivery, choice of vector and duration of treatment is needed if gene therapy is to become a credible therapeutic option for peripheral arterial disease.

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.

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.

What is the optimum perioperative drug therapy following lower-extremity vein bypass surgery?

While endoluminal procedures are now commonly done for symptomatic peripheral arterial disease, vein bypass remains the gold standard for revascularization. Lower extremity vein bypass procedure success is dependent on patient factors, surgical judgment and technique, including use of medications. Cardioprotective medications have proven efficacy to decrease morbidity and mortality, but their use to improve graft patency is less well known. We review the up to date use of medications with known vascular effects that may promote graft success, as well as decrease cardiovascular events in this high risk patient group.

Meta-analysis of randomized, controlled clinical trials in angiogenesis: gene and cell therapy in peripheral arterial disease

We aim to determine the efficacy and safety of gene and cell angiogenic therapies in the treatment of peripheral arterial disease (PAD) and evaluate them for the first time by a meta-analysis. We include in the formal meta-analysis only the randomized placebo-controlled phase 2 studies with any angiogenic gene or cell therapy modality to treat patients with PAD (intermittent claudication, ulcer or critical ischemia) identified by electronic search in MEDLINE and EMBASE databases (1980 to date). Altogether, 543 patients are analyzed from six randomized, controlled trials that are comparable with regard to patient selection, study design, and endpoints. We perform the meta-analysis regarding clinical improvement (improvement of peak walk time, relief in rest pain, ulcer healing or limb salvage) and rate of adverse events. At the end of treatment, therapeutic angiogenesis shows a significantly clinical improvement as compared to placebo in patients with PAD (odds ratio [OR] = 1.437; 95% confidence interval [CI] = 1.03-2.00; P = 0.033). The response rate (improvement of peak walk time) of the pooled groups according to clinical severity does not significantly differ for gene therapy as compared with placebo in the treatment of claudicating patients (OR = 1.304; 95% CI = 0.90-1.89; P = 0.16). Otherwise, we find significant efficacy of the treatment in critical ischemia (OR = 2.20; 95% CI = 1.01-4.79; P = 0.046). The adverse events rates show a slightly significantly higher risk of potential nonserious adverse events (edema, hypotension, proteinuria) in the treated group (OR = 1.81; 95% CI = 1.01-3.38; P = 0.045). We find no differences in mortality from any cause, malignancy, or retinopathy. The patients with PAD, and particularly those with critical ischemia, improve their symptoms when treated with angiogenic gene and cell therapy with acceptable tolerability.

Secondary Prevention of Arteriosclerosis in Lower Limb Vascular Amputees: A Missed Opportunity

OBJECTIVES

To determine the numbers of patients with peripheral vascular disease prescribed secondary prevention agents following a lower limb amputation.

DESIGN

A retrospective cross sectional study.

METHODS

The clinical documentation of 107 vascular amputees (mean age 69.5, 2:1 male:female ratio) referred for prosthesis provision in 2004 and 2005 were analysed to determine levels of prescribing of anti-platelet agents, anti-coagulants and cholesterol lowering drugs.

RESULTS

Analysis of vascular amputees referred in 2004 and 2005 reveals that 41% were prescribed a statin and 39% were prescribed a statin and 60% an anti-platelet agent. While 39% of these patients were on both drugs, 32% had been prescribed neither.

CONCLUSIONS

The medical management of patients with severe peripheral vascular disease, even where their disease has led to an amputation, is sub-optimal.

Antithrombotic treatment for peripheral arterial disease

CONTEXT

Patients with peripheral arterial disease (PAD) bear a substantial risk for vascular events in the coronary, cerebral and peripheral circulations. In addition, this disorder is associated with a systemic milieu characterised by ongoing platelet activation and heightened thrombogenesis.

OBJECTIVE

To determine the optimal antithrombotic prophylaxis for patients with PAD.

DATA SOURCES

Using terms related to PAD and antithrombotic agents, we searched the following databases for relevant articles: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, the National Institutes of Health Clinical Trials Database, Web of Science, and the International Pharmaceutical Abstracts Database (search dates: 1 January 1990 to 1 January 2007). Additional articles were identified from cardiovascular and vascular surgery conference proceedings, bibliographies of review articles, and personal files.

STUDY SELECTION

We focused on randomised trials, systematic reviews and consensus guidelines of antithrombotic therapies for PAD.

DATA EXTRACTION

Detailed study information was abstracted by each author working independently.

RESULTS

Multiple studies show that patients with PAD manifest platelet hyperaggregability, increased levels of soluble platelet activation markers, enhanced thrombin generation and altered fibrinolytic potential. Many of these markers predict subsequent cardiovascular events. Available randomised trials and meta-analyses show that most available antithrombotic agents prevent major cardiovascular events and death in patients with PAD, including aspirin, aspirin/dipyridamole, clopidogrel, ticlopidine, picotamide and oral anticoagulants.

CONCLUSIONS

Although the most favourable risk-benefit profile, cost-effectiveness and overall evidence base supports aspirin in this setting, we provide scenarios in which alternatives to aspirin should be considered.

Antiplatelet therapy in peripheral occlusive arterial disease

BACKGROUND

Antiplatelet therapy (APT) in patients with peripheral occlusive arterial disease (POAD) may reduce cardiovascular (CV) morbidity and mortality by inhibiting atherothrombosis. This article reviews the current evidence for APT in patients with stable POAD and in patients undergoing revascularization procedures for POAD.

METHODS

A Medline and Pubmed literature search (January 1966 to February 2003) was conducted to identify articles relating APT and POAD. Manual cross referencing was also used.

RESULTS AND CONCLUSIONS

Meta-analyses suggest that APT (most commonly aspirin) in patients with stable POAD significantly reduces the incidence of nonfatal stroke, myocardial infarction and CV death. However, this conclusion is based on subset analysis of data predominantly involving patients with coronary and cerebrovascular atherosclerosis. There is a little direct evidence for the use of aspirin in patients with isolated POAD, but in practice, aspirin remains the most commonly used antiplatelet agent as high rates of coronary and cerebrovascular diseases are observed in this patient population. For patients with POAD without additional indicators of vascular risk, the protective effect of aspirin is unclear and dependent on the balance of risks and benefits in the individual patient. For patients undergoing peripheral revascularization, ticlopidine and aspirin in combination with dipyridamole are effective in maintaining patency after bypass procedures and following angioplasty/femoral endarterectomy. The efficacy of thienopyridines in peripheral angioplasty is uncertain, and the optimum timing and duration of APT relative to intervention are not known.

The action of dipyridamole to prevent thrombosis: practical implications for the treatment and prevention of stroke

Aggrenox (Boehringer Ingelheim, Ingelheim, Germany), a novel combination of low-dose aspirin with dipyridamole, represents a safe and promising combination alternative for mild but sustained platelet inhibition, and reduction of both arterial and venous thrombi occurrences. In a large, well-controlled randomized trial (ESPS-2 ) evaluating antiplatelet agents for stroke prevention, Aggrenox was twice as effective as monotherapy with either aspirin or dipyridamole. There is an increasing body of evidence that a delicate strategy with Aggrenox provides modest inhibition of platelet activity, especially in a chronic, long-term setting. Mild platelet inhibition beyond conventional aggregation may represent a substantial advantage over aggressive antiplatelet regimens for the treatment, and especially for secondary prevention, of cerebrovascular ischemic events. Although there is no doubt that the concept of inhibiting platelets is vital for the treatment of vascular ischemic disease in general and ischemic stroke and transient ischemic attack (TIA) in particular, the optimal degree of such inhibition still remains an unsolved mystery. It seems that the concepts of "the more, the better" and "one size fits all" may no longer be valid for ideal antiplatelet protection in such high-risk populations. Without routine individual laboratory assessment of platelet function, mild regimens have the advantage of being more suitable for the majority of patients and will contribute substantially to the success of dipyridamole. Conversely, if we can determine baseline platelet status and intelligently apply therapy based on platelet activity in each particular patient, clinical outcomes may be better. Avoiding excessive bleeding risks after aggressive strategies in patients with normal or already decreased platelet function, but targeting those who exhibit activated platelets, may improve risk stratification and save lives. Therefore, Aggrenox should be considered a drug of choice to prevent the second stroke. Eliminating, or at least minimizing, the most frequent side effect, namely transitory headaches at the beginning of therapy with Aggrenox, will benefit patients and increase the use of this agent. Should the PRoFESS (Prevention Regimen For Effectively avoiding Second Strokes) trial show an advantage in event reduction with Aggrenox over clopidogrel, the increase will be especially dramatic. In short, based on current evidence most guidelines include Aggrenox as a first-line option for secondary prevention of ischemic stroke or TIA, and some recent versions suggest it may be preferable in other clinical scenarios.

Peripheral vascular disease endovascular management in patients scheduled for cardiac surgery: a clinical-angiographic approach

BACKGROUND

Endovascular management of peripheral vascular disease before cardiac surgery is still debated. We sought to present our preliminary experience of endovascular stent placement in patients scheduled for urgent cardiac surgery.

METHODS

Between November 2003 and August 2005, 20 patients scheduled for urgent coronary surgery (13 males, mean age 72.5+/-5.3 years) underwent endovascular repair of PVD on the basis of clinical and angiographic indications. Aspirin (100 mg/day) plus low molecular weight heparin (nadroparin calcium) 100 IU/kg/12 h for urgent coronary surgical revascularization was administered after the procedure.

RESULTS

Endovascular stenting has been performed in four clinical settings: renal artery stenting prior to coronary surgery (nine patients) to decrease the impact of extracorporeal circulation on an impaired renal function, iliac artery artery angioplasty and stenting (eight patients) in order to facilitate aortic balloon pump insertion after surgery, subclavian artery angioplasty and stenting propedeutical to arterial conduits bypass surgery (one patient), carotid artery stenting before coronary surgery (two patients). All patients underwent successful endovascular repair followed by cardiac surgery. At a mean follow-up of 12+/-4.6 months all patients are alive and without evident thrombosis or restenosis of the implanted vascular stents.

CONCLUSIONS

Endovascular treatment of PVD in patients scheduled for urgent coronary surgery may be effective, relatively safe and lasting in spite of low dose antiplatelet regimen.

Intermittent claudication: an overview

Intermittent claudication (IC) is defined by leg muscle pain, cramping and fatigue brought on by ambulation/exercise; relieved on rest; and caused by inadequate blood supply and is the primary symptom of peripheral arterial disease (PAD). PAD has a detrimental effect on the quality of life. PAD is a debilitating atherosclerotic disease of the lower limbs and is associated with an increased risk of cardiovascular morbidity and mortality. IC is an extremely important marker of atheroma. Up to 60% patients with IC have significant underlying coronary and/or carotid disease and 40% of all patients suffering from IC die or suffer a stroke within 5 years of presentation. The therapeutic intervention of IC essentially aims at providing symptomatic relief and reducing the systemic cardiovascular complications. Although exercise therapy is one of the most efficacious conservative treatments for claudication, the pharmacotherapeutic goals can be best achieved through an increase in the walking capacity to improve quality of life and a decrease in rates of amputation. In the development of treatment for IC, an aggressive non-pharmacological intervention and pharmacological treatment of the risk factors associated with IC are considered. In the next 2 years, the results of major trials of drugs that stabilize and regress atherosclerosis such as statins and angiotensin converting enzyme inhibitors, and anti-platelet agents, recombinant growth factors and immune modulators will be available for IC. Levocarnitine (l-carnitine) and a derivative, propionyl levocarnitine, are emerging agents that increase the pain-free walking and improve the quality of life in IC patients by working at the metabolism and exercise performance of ischemic muscles. This article provides a comprehensive review of the pathophysiology involved, diagnosis of IC and existing and emerging pharmacotherapies with rationale for their use in its treatment.

Management of risk in peripheral artery disease: recent therapeutic advances

Peripheral artery disease (PAD) is a problem frequently encountered by physicians who care for patients with coronary heart disease, diabetes mellitus, renal insufficiency, congestive heart failure, or stroke. Patients with PAD are at heightened risk of myocardial infarction and stroke and are 6 times more likely to die of cardiovascular causes than persons without the disease. There is an urgent need for therapies that reduce the incidence of vascular complications among patients with PAD. In recent years, a number of risk-lowering therapies have been validated by randomized controlled trials enrolling large numbers of patients with PAD. The available evidence supports aggressive lifestyle modification as well as the provision of an antiplatelet agent, an HMGCoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitor, and an angiotensin-converting enzyme inhibitor for cardiovascular protection in patients with PAD. As a result of their high baseline risk and the proven effectiveness of these interventions, most patients with PAD will benefit substantially from aggressive medical therapy.

Optimal therapeutic approaches to femoropopliteal artery intervention

Superficial femoral artery disease presents a complex challenge for therapy. The extent of vascular involvement may vary from focal disease with symptoms of intermittent claudication to long total occlusions manifest as critical limb ischemia. Optimal therapy requires understanding the available options including exercise programs, pharmacologic medical therapy, surgery and interventional endovascular therapy. Rapidly advancing endovascular technology for enabling safe intervention in complex, long occlusive segments of the superficial femoral artery continues to emerge. New devices like the SafeCross wire, Excimer laser, Silverhawk Atherectomy catheter, Cryoplasty catheter and new generations of bare metal and drug-eluting nitinol stents are shifting the paradigm for therapy from surgical to more endovascular treatment even for the most complex disease presentation.

Pharmacological prevention of cardiac risk in claudicants with ischaemic heart disease

BACKGROUND

Claudicants rarely progress to critical limb ischaemia but have a threefold increase in mortality, mainly due to cardiac disease. Antithrombotic therapy, beta blockers, ACE inhibitors and statins have been shown to reduce mortality and cardiovascular morbidity in patients with ischaemic heart disease.

AIM

To investigate secondary pharmacological prevention of ischaemic heart disease in claudicants.

MATERIALS AND METHODS

We prospectively recorded comorbidity and drug treatment in 89 patients (67 men and 22 women) with a history of ischaemic heart disease recruited in a supervised exercise and lifestyle modification programme to improve claudication distance and prognosis.

RESULTS

Of the 89 cases, 40 had a history of angina only and 49 of myocardial infarction. Sixteen (18%) had diabetes, 47 (53%) had hypercholesterolaemia and 52 (58%) were hypertensive. Antithrombotic therapy was prescribed to 61 patients (68.5%), 64 (72%) with a history of myocardial infarction and 27 (67.5%) with angina only (p = 1). Beta-blockers were prescribed to 12 (13.5%) patients only, seven (15%) with a history of myocardial infarction and five (12.5%) with angina only (p = 1). Of the 47 patients with hypercholesterolaemia, 29 (62%) were on a statin.

CONCLUSION

Secondary pharmacological prevention of ischaemic heart disease in claudicants remains suboptimal, with only two thirds of patients receiving antithrombotic therapy and a small minority receiving beta blockers. Pharmacological prevention in claudicants should improve to reduce cardiac morbidity and mortality.

Antiplatelet therapy in peripheral arterial disease. Consensus statement

OBJECTIVES

Antiplatelet agents are commonly prescribed to reduce the risk of myocardial infarction, stroke and graft occlusion in patients with peripheral arterial disease (PAD). The objective was to summarise current evidence and provide recommendations on the use of antiplatelet agents in PAD.

METHODS

A consensus group was assembled including 20 specialists from a variety of fields involved in the management of patients with PAD. Data was circulated in a systematic manner prior to a main consensus meeting held in November 2001. The document subsequently produced was circulated within the group to ensure agreement in the interpretation and presentation of its findings.

RESULTS

Consensus recommendations are provided in 7 common or contentious scenarios in PAD. The recommendations are graded to reflect the evidence available and interpretations of the group. Although the document provides recommendations, it is stressed that they must be interpreted in the light of individual patient circumstances.

CONCLUSION

Antiplatelet agents have an important role in the management of patient with PAD. Although this document provides consensus recommendations, the optimum treatment in many scenarios remains unclear due to a lack of focussed clinical trials in PAD.

Antithrombotic agents for preventing thrombosis after infrainguinal arterial bypass surgery

BACKGROUND

Chronic peripheral arterial disease (PAD) is frequently treated by implantation of either an infrainguinal autologous venous or artificial graft. One-year occlusion rates for infrainguinal bypasses vary between 15 and 75%, depending on the site of distal anastomosis, length, quality, and material of the graft, but also on other factors such as proximal inflow and distal outflow conditions. To prevent graft occlusion, patients are usually treated with either an antiplatelet or antithrombotic drug, or a combination of both. Little is known about which drug is optimal to prevent infrainguinal graft occlusion.

OBJECTIVES

To evaluate whether antithrombotic treatment in patients with chronic PAD undergoing infrainguinal bypass surgery improves graft patency, limb salvage and survival by performing a meta-analysis of performed RCTs.

SEARCH STRATEGY

The search strategy was that adopted by the Cochrane Review Group on Peripheral Vascular Diseases. Additional data bases were reviewed (Reference lists of papers resulting from this search, MEDLINE from 1966-onwards and EMBASE from 1980-onwards using the terms 'anticoagulant' and 'arterial surgery'.

SELECTION CRITERIA

The methodological quality of each trial was assessed independently by at least two reviewers using the checklist provided by the Peripheral Vascular Diseases Collaborative Review Group, with emphasis on concealment of randomisation. Each trial was given an allocation score of A (clearly concealed), B (unclear if concealed), or C (clearly not concealed) and a summary score of A (low risk of bias), B (moderate risk), or C (high risk). Trials scoring A were included and those scoring C were excluded. For a trial scoring B, an attempt was made to obtain more information by contacting the author.

DATA COLLECTION AND ANALYSIS

For each trial, the number of patients originally allocated to each treatment group was extracted from the data and an 'intention to treat' analysis performed. Data collection on each trial included inclusion and exclusion criteria, patient details, type of graft, type and dose of antithrombotic therapy used, outcome, and side effects. The treatment and control groups were compared for important prognostic factors and differences described. If any of the above data was not available, further information was sought from the author. However, the heterogeneity between trials could not be tested due to inaccessible data. Data were synthesized by comparing group results.

MAIN RESULTS

The analysis including four trials which evaluated vitamin K antagonists (VKA) versus no VKA indicate, that oral anticoagulation tendentially favours venous but not artificial graft patency as well as limb salvage and survival. Two other studies comparing VKA with aspirin or aspirin/dipyridamole supported evidence for a positive effect of VKA on the patency of venous but not artificial grafts. Subgroup analysis for artificial grafts as performed in one trial showed a favourable effect of antiplatelet agents on synthetic bypasses. In two trials with a relatively small number of patients low molecular weight heparin treatment was associated with a lower incidence of early postoperative graft thrombosis compared to treatment with unfractionated heparin. In one trial infusion of antithrombin concentrate was reported to have a negative effect on intraoperative graft thrombosis necessitating the study to be stopped before termination. Perioperative administration of ancrod was compared to unfractionated heparin showing no benefit of one drug compared to the other.

REVIEWER'S CONCLUSIONS

Patients operated for an infrainguinal venous graft might benefit from treatment with VKA, whereas patients receiving an artificial graft might profit more from platelet inhibitors (aspirin). However, the evidence is not conclusive. Randomised controlled trials with larger patient numbers comparing antithrombotic therapies with either placebo or antiplatelet therapies are called for in the future.

Modifiable patient factors are associated with reverse vein graft occlusion in the era of duplex scan surveillance

OBJECTIVE

Modifiable patient factors that contribute to graft occlusion may be addressed after surgery. To determine risk factors associated with reverse vein graft (RVG) occlusion, we examined the characteristics and duplex scan surveillance (DS) patterns of patients with RVGs.

METHODS

Patients treated with RVG from January 1996 through December 2000 were identified from a prospective registry. The study population consisted of all patients with RVGs performed during the study period with grafts that subsequently occluded. Patients whose grafts remained patent served as age-matched and gender-matched control subjects. The prescribed DS regimen was every 3 months for the first postoperative year and every 6 months thereafter. Early DS failure was defined as having no DS within the first 3 months. Cox proportional hazards analysis was used to compare the two groups. Hazard ratios were calculated.

RESULTS

During the study period, 674 patients underwent RVG. Fifty-five patients with occluded RVGs were compared with 118 with patent RVGs. The follow-up period for occluded grafts was 13.40 +/- 12.59 months and for patent grafts was 32.40 +/- 15.61 months. Dialysis therapy, a known hypercoagulable state, continued smoking, and DS failure were independent factors associated with RVG occlusion. The hazards ratio for dialysis was 6.45 (95% CI, 3.07 to 13.51; P <.001), for current smoking was 4.72 (95% CI, 2.5 to 8.85; P <.001), for hypercoagulable state was 2.99 (95% CI, 1.47 to 6.10; P =.003), and for early DS failure was 2.43 (95% CI, 1.29 to 4.59; P =.006).

CONCLUSION

Continued smoking and failure to undergo DS within the first three postoperative months are modifiable factors associated with RVG occlusion. Smoking cessation and graft surveillance must be stressed to optimize patency of infrainguinal RVGs.

Potential emerging therapeutic strategies to prevent restenosis in the peripheral vasculature

Despite the availability of antiplatelet and antithrombotic therapies, recent advances in catheter and stent technology and improved operator skill, restenosis remains the most frequent problem associated with percutaneous and surgical revascularization interventions for both coronary and peripheral arterial disease. Prevention of restenosis in the coronary vasculature has been demonstrated with cilostazol, trapidil, probucol, tranilast, nitric oxide donors, and clopidogrel. Given the similarities in revascularization procedures and in the pathophysiology of restenosis, it is possible that these results may be extrapolated to the setting of restenosis in the peripheral vasculature, making trials with these agents imperative. Several new agents have shown promising preliminary results for the prevention of restenosis in the peripheral vasculature, including cilostazol, low-molecular-weight heparins, and elastase. Several nonpharmacologic treatment modalities are also under study to prevent peripheral and coronary restenosis and have shown favorable initial results. These include endovascular radiation brachytherapy, arterial gene therapy, photoangioplasty, and several novel treatment delivery systems.

Radiological Investigation and Treatment of the Critically Ischemic Limb—A Review

The contribution of radiological investigation and treatment in the management of the critically ischemic lower limb is reviewed. The methods of classifying and assessing the cause, level, and severity of the arterial disease causing the ischemia are discussed with comparison of the relative merits of the various invasive and noninvasive techniques of investigation. The development of the methods of interventional radiological management is described with an indication of the relative success of the different techniques. Newer interventional developments, including intravascular brachytherapy and gene therapy are discussed.

The role of platelets in peripheral arterial disease: therapeutic implications

Peripheral arterial disease (PAD) is associated with platelet hyperaggregability as well as an increase in morbidity and mortality from myocardial infarction and stroke. Enhanced platelet activation in PAD may substantially contribute to these adverse outcomes. A relative resistance to aspirin therapy has been reported in patients with PAD. Therefore, clopidogrel may be superior to aspirin in treatment of PAD. Furthermore, the aspirin + clopidogrel combination could be more effective than monotherapy but its risk-benefit ratio has yet to be evaluated. Clopidogrel is preferable to ticlopidine because of its safer profile and the convenience of once-daily administration. The glycoprotein (Gp) IIb/IIIa inhibitors may also find a place as short-term therapy after peripheral angioplasty. There is a need to consider the use of clopidogrel in patients who cannot tolerate aspirin. Patients who have an event while taking aspirin also present a problem. One possibility here is to substitute aspirin with clopidogrel or to add clopidogrel to the aspirin. Although these options are currently not evidence based in patients with PAD, there is emerging evidence showing that they are realistic choices.

Identification of factors predictive of lower extremity vein graft thrombosis

OBJECTIVE

The objective of this study was to assess the prognostic value of hemodynamic parameters measured with duplex ultrasound scan, together with other important graft and patient characteristics, in predicting lower extremity vein graft thrombosis.

METHODS

A total of 165 lower extremity vein grafts were entered prospectively into a postoperative duplex ultrasound scan surveillance program with examinations performed at 1, 2, 3, 4, 6, 9, 12, 18, and 24 months, and annually thereafter. Duplex scan-derived blood flow velocity measurements were recorded at 1562 patient visits over 7 years. Graft patency was determined after each visit, and an analysis of factors predictive of vein graft thrombosis was performed with Poisson regression.

RESULTS

Thirty-two episodes of first-time graft thrombosis occurred, 23 of which were permanent. One-, 3-, and 5-year secondary graft patency rates were 90%, 86%, and 79%, respectively. In multivariate analyses, duplex scan velocity measurements predictive of lower extremity graft thrombosis included the maximum velocity ratio (Vr) in association with a graft stenosis and the mean graft peak systolic velocity (MGV) within nonstenotic portions of the body of the graft. The incidence of graft thrombosis among grafts without inflow/outflow stenoses, with Vr less than 3.5, and with MGV 50 cm/s or more, was 2.9% per year. Incidence rates were considerably higher among grafts with a of Vr of 3.5 or more (incidence rate ratio = 7.0; 95% CI, 3.4-14.6) or an MGV less than 50 cm/s (incidence rate ratio = 6.5; 95% CI, 3.3-13.1). In grafts without identifiable inflow, outflow, or graft stenoses, there was no association between MGV and the risk of graft thrombosis.

CONCLUSION

Duplex scan velocity measurements are valid predictors of impending graft thrombosis. A Vr of 3.5 or more and an MGV less than 50 cm/s are the best predictive measures. Repair of correctable graft lesions with a Vr of 3.5 or more, or inflow, outflow, or graft lesions associated with an MGV less than 50 cm/s are recommended. Grafts without detectable inflow, outflow, or graft stenoses, regardless of MGV, may be safely followed.