Extracardiac vascular disease and effectiveness of sustained clopidogrel treatment

Antithrombotic Therapy for Symptomatic Peripheral Arterial Disease: A Systematic Review and Network Meta-Analysis

BACKGROUND

High-quality evidence from trials directly comparing single antiplatelet therapies in symptomatic peripheral arterial disease (PAD) to dual antiplatelet therapies or acetylsalicylic acid (ASA) plus low-dose rivaroxaban is lacking. Therefore, we conducted a network meta-analysis on the effectiveness of all antithrombotic regimens studied in PAD.

METHODS

A systematic search was conducted to identify randomized controlled trials. The primary endpoints were major adverse cardiovascular events (MACE) and major bleedings. Secondary endpoints were major adverse limb events (MALE) and acute limb ischaemia (ALI). For each outcome, a frequentist network meta-analysis was used to compare relative risks (RRs) between medication and ASA. ASA was the universal comparator since a majority of studies used ASA as in the reference group.

RESULTS

Twenty-four randomized controlled trials were identified including 48,759 patients. With regard to reducing MACE, clopidogrel [RR 0.78, 95% confidence interval (CI) 0.66-0.93], ticagrelor (RR 0.79, 95% CI 0.65-0.97), ASA plus ticagrelor (RR 0.79, 95% CI 0.64-0.97), and ASA plus low-dose rivaroxaban (RR 0.84, 95% CI 0.76-0.93) were more effective than ASA, and equally effective to one another. As compared to ASA, major bleedings occurred more frequently with vitamin K antagonists, rivaroxaban, ASA plus vitamin K antagonists, and ASA plus low-dose rivaroxaban. All regimens were similar to ASA concerning MALE, while ASA plus low-dose rivaroxaban was more effective in preventing ALI (RR 0.67, 95% CI 0.55-0.80). Subgroup analysis in patients undergoing peripheral revascularization revealed that ≥ 3 months after intervention, evidence of benefit regarding clopidogrel, ticagrelor, and ASA plus ticagrelor was lacking, while ASA plus low-dose rivaroxaban was more effective in preventing MACE (RR 0.87, 95% CI 0.78-0.97) and MALE (RR 0.89, 95% CI 0.81-0.97) compared to ASA. ASA plus clopidogrel was not superior to ASA in preventing MACE ≥ 3 months after revascularization. Evidence regarding antithrombotic treatment strategies within 3 months after a peripheral intervention was lacking.

CONCLUSION

Clopidogrel, ticagrelor, ASA plus ticagrelor, and ASA plus low-dose rivaroxaban are superior to ASA monotherapy and equally effective to one another in preventing MACE in PAD. Of these four therapies, only ASA plus low-dose rivaroxaban provides a higher risk of major bleedings. More than 3 months after peripheral vascular intervention, ASA plus low-dose rivaroxaban is superior in preventing MACE and MALE compared to ASA but again at the cost of a higher risk of bleeding, while other treatment regimens show non-superiority. Based on the current evidence, clopidogrel may be considered the antithrombotic therapy of choice for most PAD patients, while in patients who underwent a peripheral vascular intervention, ASA plus low-dose rivaroxaban could be considered for the long-term (> 3 months) prevention of MACE and MALE.

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).

Prescribing patterns of antiplatelet agents are highly variable after lower extremity endovascular procedures

BACKGROUND

The use of antiplatelet and antithrombotic agents after peripheral vascular interventions is a common clinical practice despite a lack of clear convincing evidence or accepted practice guidelines. The goal of this study was to assess surgeons' prescribing practices after endovascular procedures for lower extremity arterial occlusive disease.

METHODS

Attendees at a national vascular meeting were asked to complete a voluntary survey indicating their prescribing practices of antiplatelet/antithrombotic agents for the following procedures: iliac bare-metal stent, iliac covered stent, infrainguinal balloon angioplasty, infrainguinal bare-metal stent, infrainguinal covered stent, infrainguinal atherectomy, and lower extremity cryoplasty. The respondents were given choices of aspirin (ASA) alone, clopidogrel alone, ASA/clopidogrel combined, warfarin alone, or ASA/clopidogrel/warfarin combined. They were also asked to indicate their preferred length of treatment for each medication or combination of medications for each procedure: 1, 3, 6, or 12 months.

RESULTS

There were 51 respondents (48 vascular surgeons and 3 vascular fellows) with an average of 11 ± 6.4 years of experience and practicing in a university hospital (48%), community hospital (44%), or combined university/Veterans A hospital (6%) setting. The majority of respondents (98%) prescribe an antiplatelet agent for patients with peripheral arterial disease using 81 mg of ASA preferentially. Most surgeons do not obtain genetic testing (i.e., cytochrome P450, polypeptide 19 [CYP2C19] polymorphism) for antiplatelet effectiveness. The most common antiplatelet/antithrombotic medication of choice after lower extremity endoluminal therapy was a combination of ASA/clopidogrel. However, the duration of medical treatment was variable, with a 1- to 3-month course being the most common. The use of the ASA/clopidogrel combination increased with further distal endovascular treatment and the placement of stents versus angioplasty. In the vast majority of ASA-only responses, ASA was administered for at least 12 months if not recommended for life. Although the majority of surgeons would recommend dual antiplatelet therapy (52-77%), there was no consensus regarding the duration of treatment.

CONCLUSIONS

The antiplatelet/antithrombotic prescribing practices of vascular surgeons after lower extremity endovascular procedures are highly variable. Multicenter randomized controlled trials are needed to define optimal treatment efficacy and define the much-needed practice guidelines.

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.

Polyvascular atherosclerotic disease: recognizing the risks and managing the syndrome

BACKGROUND

Patients with an initial ischemic event secondary to atherosclerosis have an increased risk of suffering a recurrent event not only in the same vascular territory, but in other territories as well. Patients with polyvascular disease, or atherosclerotic disease in more than one vascular territory, have worse clinical outcomes than those with disease in a single vascular territory. This suggests that atherosclerosis should be treated as a systemic disease with appropriately aggressive secondary preventive measures in order to prevent recurrent events throughout the arterial tree.

OBJECTIVE

To discuss relevant findings for the management of patients with polyvascular disease and provide guidance to clinicians who may not be aware of how best to manage these patients.

METHODS

Relevant English-language articles published from 1950 through February 2009 were identified by searching the Cochrane, MEDLINE, and Ovid databases using the terms 'atherosclerosis,' 'atherothrombosis,' 'cerebrovascular disease,' 'coronary artery disease,' 'cross-risk,' 'management guidelines,' 'peripheral arterial disease,' 'polyvascular,' and 'secondary prevention' either singly or in combination.

FINDINGS AND CONCLUSIONS

According to limited data from patient registries, anywhere from 15% to 30% of patients with atherosclerosis present with disease in multiple vascular territories and experience significantly greater rates of adverse cardiovascular events. Despite these findings, a search of the literature reveals a lack of studies comprised of patients with polyvascular disease only and very few reports on the results of patients with polyvascular disease enrolled in existing secondary prevention studies. Although any conclusions are limited by this small number of studies, clinicians typically treat only the initially affected territory without consideration of the other affected territories and may lack awareness of the overall atherothrombotic syndrome. In the future, clinical trials focused specifically on patients with polyvascular disease should be conducted in order to increase our knowledge on how to manage these patients. Evidence-based clinical practice guidelines are also necessary to improve the management of patients with polyvascular disease.

Appropriate secondary prevention of acute atherothrombotic events and strategies to improve guideline adherence

The use of guideline-recommended secondary prevention measures is essential for reducing the risk of subsequent events and mortality in patients who have survived an acute atherothrombotic event or have peripheral arterial disease. Although initial hospitalization provides an ideal environment to initiate such therapies, implementation of effective longterm prevention strategies is hindered by the absence of a systematic approach. In general, evidence-based clinical practice guidelines recommend antiplatelet therapy as a cornerstone of post-discharge secondary prevention, in addition to preventive measures targeting risk factors such as hypertension, dyslipidemia, cigarette smoking, and physical inactivity. Observational data indicate that, although there has been improvement over time, current utilization of guideline-recommended post-discharge treatment remains suboptimal. Recognizing the importance of a systematic approach to discharge planning, numerous hospital-based initiatives have been established. In conjunction with effective lines of communication between hospital and primary care teams, initiation of the most effective secondary prevention strategy at the time of hospital discharge will help to ensure optimal long-term management of patients after an atherothrombotic event.

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.

Prognostic value of ankle-brachial index and dobutamine stress echocardiography for cardiovascular morbidity and all-cause mortality in patients with peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) is associated with an excessive risk for cardiovascular events and mortality. To determine measures prognostic of adverse events, ankle-brachial index (ABI) was compared with dobutamine stress echocardiography (DSE) in patients referred to our vascular center for the evaluation of PAD.

METHODS

The medical records of consecutive patients referred for the concurrent evaluation of PAD and coronary artery disease (CAD) between 1992 and 1995 were reviewed for subsequent cardiovascular events and death.

RESULTS

Among 395 patients (mean age, 69.7 +/- 9.6 years; 40% women), 341 had abnormal ABI and 268 had abnormal DSE (95 fixed and 173 stress-induced wall motion abnormalities). During a mean follow-up of 4.7 years, 27.3% of patients experienced a cardiovascular event, and 39.4% died. By multivariate analysis, ABI provided the strongest prediction of all-cause mortality (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.36 to 4.05; P = .002). Conversely, DSE with inducible or fixed wall motion abnormalities showed no association with cardiovascular events or increased mortality in multivariate analysis. The only DSE variable independently predictive of mortality was decreased left ventricular ejection fraction (<50%) at peak stress (HR, 1.70; 95% CI, 1.22 to 2.36; P = .002). Statin and aspirin therapy, but not beta-blockers, were protective. There was no relation between ABI and wall motion index score at rest or after stress.

CONCLUSIONS

In high-risk patients referred to our vascular center for the evaluation of PAD, the assessment of ABI provided a strong independent prediction of all-cause mortality. Therefore, proper interpretation of this simple, affordable, and reproducible measure extends beyond the assessment of PAD severity. Although a poor left ventricular response to dobutamine was also predictive, other echo variables were not.

Clopidogrel

Clopidogrel (Plavix), Iscover) selectively and irreversibly inhibits adenosine diphosphate (ADP)-induced platelet aggregation. Long-term administration of clopidogrel was associated with a modest but statistically significant advantage over aspirin in reducing adverse cardiovascular outcomes in patients with established cardiovascular disease in the CAPRIE trial. In other large well designed multicentre trials, such as CURE, COMMIT and CLARITY-TIMI 28, the addition of clopidogrel to aspirin therapy improved outcomes in patients with acute coronary syndromes. However, some issues regarding the use of clopidogrel remain unresolved, such as the optimal loading dose in patients undergoing percutaneous coronary interventions (PCI) and the optimal treatment duration following drug-eluting intracoronary stent placement. Results of several large randomised trials, therefore, have established clopidogrel as an effective and well tolerated antiplatelet agent for the secondary prevention of ischaemic events in patients with various cardiovascular conditions, including those with ischaemic stroke or acute coronary syndromes. In addition, treatment guidelines from the US and Europe acknowledge the importance of clopidogrel in contemporary cardiovascular medicine.

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 and the vascular tree

While treatment with aspirin plus clopidogrel may be valid as an adjunct to percutaneous coronary intervention, other issues remain to be addressed before routine combination therapy is recommended for any level of atherosclerosis