Preventing atherothrombotic events in peripheral arterial disease: the use of antiplatelet therapy

Peripheral Arterial Diseases and Diabetes Mellitus: Associations With Quality of Health Measures in Patients Undergoing Percutaneous Vascular Interventions

BACKGROUND

Peripheral arterial disease (PAD) is more prevalent and severe in patients with diabetes mellitus (DM) compared with those without DM. Peripheral vascular intervention (PVI) is often used in patients failing conservative management. The association of PVI with health status in diabetic patients has yet to be determined.

METHODS

We analyzed the clinical response to PVI in DM (n = 203, 52 %) compared with non-DM patients (n = 183, 48 %), using the Peripheral Arterial Questionnaire (PAQ) for patients during baseline and a maximum 6 months after PVI. We used the PAQ summary score, which summarized the patients' level of physical and social function, patient symptoms, and overall quality of life. This represented the PAD-related Quality of Health (QOH). Our score range is between 0 (lowest health quality) and 100 (highest health quality).

RESULTS

Compared with non-DM patients, those with DM were more likely to have a history of prior PVI, an increased prevalence of PAD risk factors, and significantly lower QOH scores at baseline (32.7 ± 20 vs 37.5 ± 20.6, p = 0.02). After adjustment for baseline confounding, neither the baseline, the change, nor the final summary scores were significantly different between groups, suggesting similar symptomatic and functional improvement in non-DM and DM patients post-PVI.

CONCLUSIONS

Following PVI, PAD-specific health status showed a similar improvement in patients with and without DM, illustrating that use of this strategy among patients with multiple comorbidities or diffuse PAD as useful.

Diabetic foot ulcers: Classification, risk factors and management

Diabetic foot ulceration is a devastating complication of diabetes that is associated with infection, amputation, and death, and is affecting increasing numbers of patients with diabetes mellitus. The pathogenesis of foot ulcers is complex, and different factors play major roles in different stages. The refractory nature of foot ulcer is reflected in that even after healing there is still a high recurrence rate and amputation rate, which means that management and nursing plans need to be considered carefully. The importance of establishment of measures for prevention and management of DFU has been emphasized. Therefore, a validated and appropriate DFU classification matching the progression is necessary for clinical diagnosis and management. In the first part of this review, we list several commonly used classification systems and describe their application conditions, scope, strengths, and limitations; in the second part, we briefly introduce the common risk factors for DFU, such as neuropathy, peripheral artery disease, foot deformities, diabetes complications, and obesity. Focusing on the relationship between the risk factors and DFU progression may facilitate prevention and timely management; in the last part, we emphasize the importance of preventive education, characterize several of the most frequently used management approaches, including glycemic control, exercise, offloading, and infection control, and call for taking into account and weighing the quality of life during the formulation of treatment plans. Multidisciplinary intervention and management of diabetic foot ulcers (DFUs) based on the effective and systematic combination of these three components will contribute to the prevention and treatment of DFUs, and improve their prognosis.

Antiplatelet agents for intermittent claudication

BACKGROUND

Peripheral arterial disease (PAD) is common and is a marker of systemic atherosclerosis. Patients with symptoms of intermittent claudication (IC) are at increased risk of cardiovascular events (myocardial infarction (MI) and stroke) and of both cardiovascular and all cause mortality.

OBJECTIVES

To determine the effectiveness of antiplatelet agents in reducing mortality (all cause and cardiovascular) and cardiovascular events in patients with intermittent claudication.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases group searched their Specialised Register (last searched April 2011) and CENTRAL (2011, Issue 2) for publications on antiplatelet agents and IC. In addition reference lists of relevant articles were also searched.

SELECTION CRITERIA

Double-blind randomised controlled trials comparing oral antiplatelet agents versus placebo, or versus other antiplatelet agents in patients with stable intermittent claudication were included. Patients with asymptomatic PAD (stage I Fontaine), stage III and IV Fontaine PAD, and those undergoing or awaiting endovascular or surgical intervention were excluded.

DATA COLLECTION AND ANALYSIS

Data on methodological quality, participants, interventions and outcomes including all cause mortality, cardiovascular mortality, cardiovascular events, adverse events, pain free walking distance, need for revascularisation, limb amputation and ankle brachial pressure indices were collected. For each outcome, the pooled risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) was calculated.

MAIN RESULTS

A total of 12 studies with a combined total of 12,168 patients were included in this review. Antiplatelet agents reduced all cause (RR 0.76, 95% CI 0.60 to 0.98) and cardiovascular mortality (RR 0.54, 95% CI 0.32 to 0.93) in patients with IC compared with placebo. A reduction in total cardiovascular events was not statistically significant (RR 0.80, 95% CI 0.63 to 1.01). Data from two trials (which tested clopidogrel and picotamide respectively against aspirin) showed a significantly lower risk of all cause mortality (RR 0.73, 95% CI 0.58 to 0.93) and cardiovascular events (RR 0.81, 95% CI 0.67 to 0.98) with antiplatelets other than aspirin compared with aspirin. Antiplatelet therapy was associated with a higher risk of adverse events, including gastrointestinal symptoms (dyspepsia) (RR 2.11, 95% CI 1.23 to 3.61) and adverse events leading to cessation of therapy (RR 2.05, 95% CI 1.53 to 2.75) compared with placebo; data on major bleeding (RR 1.73, 95% CI 0.51, 5.83) and on adverse events in trials of aspirin versus alternative antiplatelet were limited. Risk of limb deterioration leading to revascularisation was significantly reduced by antiplatelet treatment compared with placebo (RR 0.65, 95% CI 0.43 to 0.97).

AUTHORS' CONCLUSIONS

Antiplatelet agents have a beneficial effect in reducing all cause mortality and fatal cardiovascular events in patients with IC. Treatment with antiplatelet agents in this patient group however is associated with an increase in adverse effects, including GI symptoms, and healthcare professionals and patients need to be aware of the potential harm as well as the benefit of therapy; more data are required on the effect of antiplatelets on major bleeding. Evidence on the effectiveness of aspirin versus either placebo or an alternative antiplatelet agent is lacking. Evidence for thienopyridine antiplatelet agents was particularly compelling and there is an urgent need for multicentre trials to compare the effects of aspirin against thienopyridines.

Cardiovascular event rates in patients with cerebrovascular disease and atherothrombosis at other vascular locations: results from 1-year outcomes in the Japanese REACH Registry

The REduction of Atherothrombosis for Continued Health (REACH) Registry is a large, international, prospective cohort of patients with atherothrombosis or multiple (>or=3) risk factors (MRFs) for atherothrombosis. Japanese patients (n=5193) were enrolled into the REACH registry between August and December 2004. One-year event rate in patients with cerebrovascular disease (CVD) was compared with that of patients with symptomatic atherothrombosis at other locations. After one year (n=5021), patients with CVD (n=1962) experienced a higher rate of non-fatal strokes than patients with coronary artery disease (CAD), peripheral artery disease (PAD) or MRFs alone (2.77% vs. 1.28%, 2.07% and 1.56%, respectively), but a lower rate of non-fatal myocardial infarction (0.45% vs. 1.31%, 0.77% and 0.66%, respectively). Patients with CVD plus disease in >or=1 other vascular bed had higher rates of cardiovascular events than patients with CVD alone. Overall, event rates including non-fatal stroke, non-fatal myocardial infarction and cardiovascular death were higher for patients with CVD and PAD than for patients with CVD and CAD. Asymptomatic carotid stenosis >or=70% and ankle-brachial index <0.9 were significant predisposing factors for stroke. Patients with CVD and co-existing atherothrombotic diseases had a high risk of recurrent events, including events arising in other vascular beds than originally diagnosed.

Peripheral and cerebrovascular atherosclerotic disease in diabetes mellitus

Diabetes mellitus is frequently associated with atherosclerotic vascular disease involving the coronary, peripheral and cerebrovascular circulation. Compared with non-diabetic counterparts, peripheral arterial disease (PAD) in diabetic individuals is more diffuse and often involves the popliteal and below-knee arteries. The goal of treatment in diabetic patients with PAD, as in other patients with this condition, is to aggressively treat atherosclerotic risk factors to reduce future cardiovascular events as well as to improve symptoms of claudication and prevent limb amputation. Diabetes is also associated with a heightened risk of stroke which is a common cause of morbidity and mortality in diabetic individuals. Optimal blood pressure control is paramount in reducing the future risk of stroke in these patients. Clinicians need to be aware of the strong association between diabetes and non-coronary atherosclerosis and use appropriate medical and interventional treatments to reduce the associated disability and mortality in these patients.

Aspirin in cardiology--benefits and risks

AIMS

To review the current knowledge of the benefits and risks of long-term aspirin therapy for the prevention of cardiovascular disease.

METHODS

Relevant articles published in English between 1996 and 2006 were obtained from the Current Contents Science Edition, EMBASE and MEDLINE databases.

RESULTS

Secondary aspirin prophylaxis is effective in reducing the risk of ischaemic events in patients with cardiovascular disease. However, its utility in reducing primary ischaemic events is more controversial; it appears to reduce the incidence of ischaemic stroke, but increase the incidence of haemorrhagic stroke. Aspirin therapy can also lead to an increased risk of gastrointestinal ulcers, upper gastrointestinal bleeding and other haemorrhagic complications. Lower doses of aspirin are associated with a reduced risk of gastrointestinal side effects and are equally effective in reducing cardiovascular risk. Co-therapy with non-steroidal anti-inflammatory drugs, clopidogrel or warfarin increases the risk of gastrointestinal side effects, while co-therapy with proton pump inhibitors reduces it.

CONCLUSIONS

Both the benefits and risks need to be considered carefully when prescribing aspirin, particularly in primary prevention. Patients should be prescribed lower doses rather than higher doses of aspirin in line with prescribing guidelines. Co-prescription of a proton pump inhibitors may be necessary in patients at high risk for upper gastrointestinal complications.

Diagnosis and Treatment of Peripheral Arterial Disease Compared with Other Atherosclerotic Vascular Diseases in a University Primary Care Clinic

BACKGROUND

Despite the fact that peripheral arterial disease (PAD) significantly increases the risk of cardiovascular mortality, it is significantly underdiagnosed and undertreated. The purpose of this study was to evaluate the practice at a northeast Tennessee university primary care clinic regarding the diagnosis and treatment of PAD.

METHODS

A retrospective medical record survey was conducted to evaluate practice patterns in diagnosing and treating PAD in a university primary care clinic. A clinic population of 711 patients was selected using International Classification of Diseases-9 codes for coronary artery disease (CAD), cerebovascular disease (CVD), and/or PAD. A sample of 180 patients (25.3%) was randomly selected using a systematic statistical method. Of these, 125 patients met the diagnostic criteria for CAD, CVD, and/or PAD. The study covered a 3-year period, from July 2001 until June 2004. Demographic and other data, including the use of antiplatelet therapy, were collected.

RESULTS

One hundred ten patients met all of the inclusion and exclusion criteria. Thirty-nine percent were males, and 61% were females. Overall, 79% had CAD, 53% had CVD, and 25% had PAD. Almost half of the patients had some combination of these. Only about 2% had PAD only compared with 36% with CAD only and 17% with CVD only. Although the prevalence of CAD and CVD (among other atherosclerotic vascular diseases) in our clinic was comparable to national figures, the prevalence of PAD was significantly lower (p = .004). The overall use of any antiplatelet agent was 84.2% for patients with only CAD and 80% for only CVD. There was not an adequate number of patients with only PAD to evaluate the use of antiplatelet therapy in this group.

CONCLUSION

The low prevalence of PAD only (most PAD patients had coexisting CAD and CVD) indicates that PAD is underdiagnosed at our clinic. There was suboptimal use of aspirin and other antiplatelet drugs among patients with atherosclerotic vascular disease.

Peripheral arterial disease in patients with diabetes

Peripheral arterial disease (PAD) is a chronic, lifestyle-limiting disease and is an independent predictor of cardiovascular and cerebrovascular ischemic events. Despite the recognition that PAD is associated with a marked increase in the risk of ischemic events, this particular manifestation of systemic atherosclerosis is largely underdiagnosed and undertreated. The risk of PAD is markedly increased among individuals with diabetes, and ischemic event rates are higher in diabetic individuals with PAD than in comparable non-diabetic populations. Consequently, early diagnosis and treatment of PAD in patients with diabetes is critically important in order to reduce the risk of cardiovascular events, minimize the risk of long-term disability, and improve quality of life. A diagnosis of PAD in patients with diabetes mandates a multi-faceted treatment approach, involving aggressive risk-factor modification, antiplatelet therapy, and revascularization procedures. The American Diabetes Association recently issued a consensus statement on the epidemiology, pathophysiology, diagnosis, and management of PAD in patients with diabetes. This article will review the clinical implications of the consensus statement and highlight the treatment options available in order to help prevent future ischemic events in diabetic individuals with PAD.

Suboptimal intensity of risk factor modification in PAD

This study extends earlier trials indicating that atherosclerosis risk factors are underdetected and undertreated in peripheral arterial disease (PAD) patients. Recognition and treatment of hyperlipidemia and hypertension in PAD patients is suboptimal. Diabetes appears to be detected more frequently although glycemic control is still suboptimal. The use of antiplatelet therapy is particularly underutilized. Additionally, despite the demonstrated efficacy of regular exercise in PAD patients, almost half of the study sample was sedentary. Approximately one third of the current study sample was overweight and nearly one third was obese by ATP-III guidelines. Only 31% of subjects were taking dietary measures to improve their cardiovascular health, and even fewer were physically active. To rectify suboptimal management of risk factors, there is a need for increased public awareness of PAD, reimbursement and implementation of screening programs and more aggressive treatment. Future studies are needed to examine innovative interventions for identification and management of cardiovascular risk factors in patients with PAD.

Lipid-lowering therapy in patients with peripheral arterial disease

Peripheral arterial disease (PAD) is a prevalent, chronic, and progressive atherosclerotic disease process involving the conduit vessels of the extremities. Most patients who present with objective signs of PAD are asymptomatic. These patients are at an increased risk of dying from cardiovascular events. Lipid management is the mainstay of risk-factor modification for patients with cardiovascular disease. Some evidence suggests that hypocholesterolemic drugs may halt the progression of atherosclerotic peripheral vascular disease. More recently, treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) inhibitors have demonstrated improved function in patients with symptomatic peripheral vascular disease. This paper reviews the role of lipid therapy in patients with peripheral arterial disease with focus on functional improvement and symptomatic relief based on the available data.

Lower extremity arterial occlusive disease: Role of percutaneous revascularization

Percutaneous endovascular interventions for peripheral arterial disease are indicated in carefully selected patients with favorable anatomy and associated clinical symptoms. Although endovascular therapy appears to be hemodynamically equivalent to other modalities in isolated iliac disease, this does not appear to be the case for infrainguinal disease, particularly when the disease is diffuse and extensive. Such disease in these beds can often be treated surgically, although there is an increasing role for percutaneous therapies, particularly in patients at higher surgical risk. Catheter-based therapy should be considered an integral part of comprehensive medical therapy in patients with lower extremity peripheral arterial disease. Embarking on an endovascular approach to therapy should involve a frank physician-patient discussion of the risks, benefits, and durability of the proposed procedure tailored to anatomic locale and patient-specific factors.

The effect of clopidogrel, aspirin and both antiplatelet drugs on platelet function in patients with peripheral arterial disease

Peripheral arterial disease (PAD) is associated with platelet hyperactivity. Aspirin and clopidogrel, two platelet inhibitors, act by different mechanisms. Aspirin inhibits thromboxane A2 synthesis and clopidogrel acts on the P2Y12 platelet ADP receptor. We evaluated the effect of clopidogrel (75 mg/day), aspirin (75 mg/day) and then both drugs on several platelet function indices in patients with PAD (n = 20). There was a significant (P = 0.0001) decrease in ADP-induced aggregation, after clopidogrel but not after taking aspirin. Clopidogrel plus aspirin significantly decreased spontaneous platelet aggregation (SPA) (P = 0.01 to P = 0.002) but SPA was not significantly altered by either aspirin or clopidogrel monotherapy. Similarly, monotherapy did not inhibit serotonin (5HT)-induced aggregation but there was a sigificant inhibition (P = 0.03 to P < 0.02) after combination therapy. ADP (0.8 microM)-induced platelet shape change (PSC) was significantly inhibited by clopidogrel (P = 0.004) or aspirin (P = 0.01). This was also true for 5HT-induced PSC (clopidogrel, P = 0.01; aspirin, P = 0.03). Soluble P-selectin decreased significantly (from 32 +/- 24 to 25 +/- 17 ng/ml, P = 0.04) with combination therapy. Plasma platelet-derived growth factor and intraplatelet 5HT levels were not altered by combination therapy. In PAD, clopidogrel is a more potent inhibitor of ADP-induced platelet activation than aspirin; combination therapy is more effective than clopidogrel or aspirin monotherapy. These potentially clinically relevant findings should be evaluated in appropriately designed trials.

Peripheral Arterial Disease: Pathophysiology, Risk Factors, and Role of Antithrombotic Therapy

OBJECTIVE

To provide an overview of the impact of peripheral arterial disease (PAD) and the steps that can be taken to reduce its burden through greater awareness of the disease, improved diagnosis, and better treatment, with emphasis on the use of antiplatelet agents.

DATA SOURCES

Recent (1990-2003) published scientific literature, as identified by the author through Medline searches, using the terms peripheral arterial disease, atherothrombosis, pathophysiology, risk factors, treatment, clinical trials, and reviews on treatment.

STUDY SELECTION

Recent systematic English-language review articles and reports of controlled randomized clinical trials were screened for inclusion.

DATA SYNTHESIS

PAD is a distinct atherothrombotic syndrome marked by stenosis and occlusion of peripheral arterial beds, typically those in the lower extremities. Symptoms range from intermittent claudication (IC) during exercise to peripheral limb ischemia requiring limb amputation. IC, the most common symptom, is experienced by 2% to 3% of men and 1% to 2% of women aged 60 years and older. Despite its recognition as a major atherothrombotic risk factor, PAD is not widely appreciated by clinicians, and most cases remain undiagnosed. Asymptomatic PAD, as indicated by a reduced ankle brachial systolic pressure index, should alert the health care provider to the presence of diffuse atherothrombotic disease and need for treatment. Risk factors for development and progression of PAD include smoking, hypertension, diabetes, hyperlipidemia, and physical inactivity. The aim of pharmacotherapy is to improve the symptoms of PAD (especially IC), defer onset of limb-threatening ischemia, and improve long-term survival. Successful treatment strategies include risk factor modification, particularly smoking cessation; initiation of regular exercise; control of hypertension, diabetes, and hyperlipidemia; and use of antiplatelet agents to reduce the risk of atherothrombotic events. Available data suggest that aspirin reduces morbidity and mortality in PAD, while clopidogrel reduces the risk of atherothrombotic events such as myocardial infarction and stroke in these patients.

CONCLUSION

Increased awareness among members of the health care community about the prevalence of PAD and benefits associated with risk-factor reduction and antiplatelet therapy could produce substantial decreases in the burden of this disease.

Platelet ADP receptor antagonists: ticlopidine and clopidogrel

The central role of platelets in the pathophysiology of arterial vascular disease has focused attention on the development of effective platelet inhibitor modalities to mitigate the clinical consequences of atherothrombotic disease. Aspirin has been the gold standard of therapy and is effective in cerebral, coronary and peripheral arterial disease with a 25% reduction in myocardial infarction, stroke and vascular death. The platelet ADP receptor antagonists were developed to further improve the clinical results of therapy. Ticlopidine provides an additional 10% relative risk reduction over aspirin alone in stroke prevention and coronary stent placement. However, ticlopidine is accompanied by occasional life-threatening adverse hematological events. The action of clopidogrel is similar to that of ticlopidine, and it is comparably effective. However, the side-effect profile of clopidogrel is much more favorable.

The effect of a loading dose (300 mg) of clopidogrel on platelet function in patients with peripheral arterial disease

Clopidogrel acts on the P2Y12 adenosine diphosphate (ADP) purinergic receptors on human platelets. The aim of this study was to establish if a loading dose of clopidogrel inhibits platelet activation in patients with peripheral arterial disease (PAD). Two indices of platelet activation were considered: platelet shape change (PSC) and aggregation. Citrated blood was collected from ten PAD patients who were not on aspirin, at baseline (0 hours) and 2 and 4 hours after these patients ingested a loading dose (300 mg) of clopidogrel. ADP (5 micromo/L)-induced platelet aggregation in whole blood was inhibited after 2 hours (free platelet count, 47% +/- 19% vs. 68% +/- 15%; p < or = 0.001) and 4 hours (47% +/- 19% vs. 66% +/- 16%; p < or = 0.001). There was also a significant inhibition of 5- hydroxytryptamine (SHT, 5.0 micromol/L)-induced platelet aggregation at 2 hours. This trend was also observed for 10-micomol/L ADP-induced aggregation. ADP (0.3-0.4 micromol/L)-induced PSC was significantly inhibited at 4 hours (increase in median platelet volume, 6.3%, 1.8-10.7 vs. 1.2%, 0-5.3; p = 0.01). 5HT (0.5 micromol/L)-induced PSC at 4 hours was also significantly inhibited (8.1, 5.3-10.6 vs. 3.0, 0-8.2; p = 0.03). A loading dose of clopidogrel (300 mg) inhibits platelet activation in PAD patients, as early as 2 hours. To the authors' knowledge, no other study considered the effect of a loading dose of clopidogrel in PAD.