The effect of long-term clopidogrel use on neointimal formation after percutaneous coronary intervention

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).

Effects of P2Y12 receptor antagonists beyond platelet inhibition--comparison of ticagrelor with thienopyridines

The effect and clinical benefit of P2Y12 receptor antagonists may not be limited to platelet inhibition and the prevention of arterial thrombus formation. Potential additional effects include reduction of the pro-inflammatory role of activated platelets and effects related to P2Y12 receptor inhibition on other cells apart from platelets. P2Y12 receptor antagonists, thienopyridines and ticagrelor, differ in their mode of action being prodrugs instead of direct acting and irreversibly instead of reversibly binding to P2Y12 . These key differences may provide different potential when it comes to additional effects. In addition to P2Y12 receptor blockade, ticagrelor is unique in having the only well-documented additional target of inhibition, the equilibrative nucleoside transporter 1. The current review will address the effects of P2Y12 receptor antagonists beyond platelets and the protection against arterial thrombosis. The discussion will include the potential for thienopyridines and ticagrelor to mediate anti-inflammatory effects, to conserve vascular function, to affect atherosclerosis, to provide cardioprotection and to induce dyspnea.

Predictors of in-stent stenosis and occlusion after endovascular treatment of intracranial vascular disease with the Willis covered stent

Covered stent placement has emerged as a promising therapeutic option for intracranial vascular lesions. However, in-stent stenosis and occlusion continue to be important concerns with the use of a covered stent, which is more thrombogenic than other types of stents. The purpose of this study was to determine predictors of in-stent stenosis and occlusion for covered stents used in the treatment of intracranial vascular diseases. Clinical, procedural and angiographic data of 46 patients with 49 intracranial vascular lesions treated with the Willis covered stent (Micro-Port, Shanghai, China) between April 2005 and October 2010 were collected and analyzed retrospectively. Univariate analysis and multivariate logistic regression analysis were performed to determine the factors predictive of in-stent stenosis and/or occlusion of the stents. In-stent stenosis and/or occlusion were documented at angiography in six patients with six lesions, and no stenoses or occlusions were seen at angiography in the remaining 40 patients with 43 lesions. Univariate analysis revealed that hypertension, post-procedure irregular antiplatelet therapy and cerebrovascular arteriosclerosis were associated with in-stent stenosis and/or occlusion. By multivariate logistic regression analysis, post-procedure irregular antiplatelet therapy (odds ratio [OR]=15; 95% confidence interval [CI], 1.172-192.004; p=0.037) and cerebrovascular arteriosclerosis (OR=19; 95% CI, 1.374-262.659; p=0.028) were independent predictors of in-stent stenosis and/or occlusion. Thus, post-procedure irregular antiplatelet therapy and coexistent cerebrovascular arteriosclerosis appear to increase the risk of in-stent stenosis and/or occlusion of covered stents in the treatment of intracranial vascular disease.

Renal artery stenosis: prevalence of, risk factors for, and management of in-stent stenosis

Atherosclerotic renal artery stenosis is common and is associated with hypertension and chronic kidney disease. More frequent use of percutaneous renal artery stent placement for the treatment of renal artery stenosis during the past 2 decades has increased the number of patients with implanted stents. In-stent stenosis is a serious problem, occurring more frequently than earlier reports suggest and potentially resulting in late complications. Currently, there are no guidelines covering the approach to restenosis after renal artery stent placement. This article reviews data on the prevalence of and risk factors for the development of in-stent stenosis and the clinical manifestations, evaluation, and treatment of in-stent stenosis and suggests a strategy for the management of patients after percutaneous renal artery stent placement.

Primary and secondary prevention of cardiovascular disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This guideline focuses on long-term administration of antithrombotic drugs designed for primary and secondary prevention of cardiovascular disease, including two new antiplatelet therapies.

METHODS

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

RESULTS

We present 23 recommendations for pertinent clinical questions. For primary prevention of cardiovascular disease, we suggest low-dose aspirin (75-100 mg/d) in patients aged > 50 years over no aspirin therapy (Grade 2B). For patients with established coronary artery disease, defined as patients 1-year post-acute coronary syndrome, with prior revascularization, coronary stenoses > 50% by coronary angiogram, and/or evidence for cardiac ischemia on diagnostic testing, we recommend long-term low-dose aspirin or clopidogrel (75 mg/d) (Grade 1A). For patients with acute coronary syndromes who undergo percutaneous coronary intervention (PCI) with stent placement, we recommend for the first year dual antiplatelet therapy with low-dose aspirin in combination with ticagrelor 90 mg bid, clopidogrel 75 mg/d, or prasugrel 10 mg/d over single antiplatelet therapy (Grade 1B). For patients undergoing elective PCI with stent placement, we recommend aspirin (75-325 mg/d) and clopidogrel for a minimum duration of 1 month (bare-metal stents) or 3 to 6 months (drug-eluting stents) (Grade 1A). We suggest continuing low-dose aspirin plus clopidogrel for 12 months for all stents (Grade 2C). Thereafter, we recommend single antiplatelet therapy over continuation of dual antiplatelet therapy (Grade 1B).

CONCLUSIONS

Recommendations continue to favor single antiplatelet therapy for patients with established coronary artery disease. For patients with acute coronary syndromes or undergoing elective PCI with stent placement, dual antiplatelet therapy for up to 1 year is warranted.

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.

Association between the efficacy of dual antiplatelet therapy and the development of in-stent neointimal hyperplasia in porcine coronary arteries

OBJECTIVE

We set out to compare the effectiveness of platelet aggregation therapy in association with the development of in-stent neointimal hyperplasia in porcine coronary arteries.

METHODS

Thirty-two pigs underwent coronary stenting with bare-metal stents under general anaesthesia. One hundred milligrams of aspirin and loading doses of either 300 mg clopidogrel (group C, n=13) or 2 x 500 mg ticlopidine (group T, n=19) were administered before intervention. During the follow-up, the animals received a daily dose of 100 mg aspirin and 75 mg clopidogrel or 2 x 250 mg ticlopidine, respectively. After 4 weeks, the histopathological and histomorphometric parameters of the explanted stented coronaries were assessed. Levels of circulating cytokines and platelet activation factors were measured. ADP-induced and collagen-induced aggregation was measured immediately before stenting and then every 3rd day. The aggregation profiles were calculated and correlated with the histological parameters.

RESULTS

The fibrin deposition scores and inflammation scores were higher in group T than in group C, with similar injury scores. Endothelialization was complete in both groups. A significantly lower neointimal area (1.08+/-0.36 vs. 1.58+/-0.5, group C vs. T, P=0.026) and percentage of area stenosis (29.8+/-12.1 vs. 44.3+/-16.3, group C vs. T, P=0.032) were observed in group C. The loading dose of clopidogrel significantly reduced the platelet activation parameters before the first angiography as compared with ticlopidone. Clopidogrel treatment resulted in a significantly better aggregation profile relative to ticlopidine (mean ADP-induced aggregation: 28.4+/-9.1 vs. 52.5+/-12.0%, P<0.001). Significant (P<0.05) positive linear correlations were observed between the ADP-induced aggregation profile and the neointimal area (r=0.584), percentage of area stenosis (r=0.666), inflammation (r=0.476) and fibrin deposition (r=0.496).

CONCLUSION

The effectiveness of dual antiplatelet therapy plays an important role in the inhibition of in-stent neointimal hyperplasia.

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.

Brief review: Coronary drug-eluting stents and anesthesia

PURPOSE

Anesthesiologists managing patients with drug-eluting stents (DES) face the challenge of balancing the risks of bleeding vs perioperative stent thrombosis (ST). This article reviews DES and the influence of antiplatelet medications related to their use. A perioperative management algorithm is suggested. Novel P2Y12 antagonists currently under investigation, including cangrelor and prasugrel are considered, as well as their potential role in modification of perioperative cardiovascular risks and management of patients with DES.

SOURCE

A PubMed search of the relevant literature over the period 1985-2005 was undertaken using the terms "drug-eluting stent", "coronary artery stent", "bare metal stent", "antiplatelet medication", "aspirin", "clopidogrel."

PRINCIPAL FINDINGS

Delayed re-endothelialization may render both sirolimus-eluting and paclitaxel-eluting stents susceptible to thrombosis for a longer duration than bare metal stents. Stent thrombosis may be associated with resistance to antiplatelet medication. In patients with a DES, a preoperative cardiology consultation is essential. Elective surgery should be postponed if the duration between DES placement and noncardiac surgery is less than six months. For semi-emergent procedures, both aspirin and clopidogrel should be continued during surgery unless clearly contraindicated by the nature of the surgery. If the risk of bleeding is high, then modification of antiplatelet medications should be considered on a case-by-case basis.

CONCLUSION

A profound increase in the number of patients with DES requires anesthesiologists to be familiar with their associated antiplatelet medications, and strategies for risk modification of ST and possible hemorrhagic complications in the perioperative setting.

Renal artery stent revascularization with embolic protection in patients with ischemic nephropathy

A prospective analysis of renal artery stent revascularization with distal embolic protection in a high-risk patient population with ischemic nephropathy is presented. A total of 63 patients (median age 70.2 years, range 54-86 years) had significant atherosclerotic stenosis of 83 renal arteries documented on pre-procedural imaging. All patients had baseline chronic renal insufficiency with a documented deterioration in renal function in the 6 months before revascularization. The endovascular technique used in all patients involved primary passage of an embolic filter into the distal main renal artery followed by primary stent deployment with a balloon expandable stainless steel stent. The filter baskets were recaptured and contents submitted for pathological analysis. At 6 months post-intervention, 97% of patients demonstrated stabilization or improvement in renal function. Only 3% of patients had an inexorable decline in renal function, unchanged by the intervention. After a mean follow up of 16.0 months (6-27), 94% of patients demonstrated stabilization or improvement in renal function. One patient suffered an acute post-procedural deterioration in renal function. In total, 60% of the filter baskets contained embolic material. This study confirms the technical feasibility of renal artery stent deployment with adjuvant embolic protection. The excellent results for renal preservation at 6 months post-intervention also suggest that a distal embolic protection device may improve the impact of percutaneous renal revascularization on progressive deterioration in renal function. The postulated mechanism is through the prevention of atheromatous embolization and the embolic yield from the distal filters supports this hypothesis. Patients most likely to receive the greatest benefit are those with mild baseline chronic renal insufficiency and a recent decline in renal function.