Benefit of clopidogrel according to timing of percutaneous coronary intervention in patients with acute coronary syndromes: further results from the Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) study

The Evolution of Antiplatelet Therapy After Percutaneous Coronary Interventions: A 40-Year Journey

Antiplatelet therapy has a critical role to play in the successful management of patients undergoing percutaneous coronary intervention (PCI). Over the past 40 years, a multitude of participants worldwide have been enrolled in trials evaluating the impact of antiplatelet agents on clinical outcomes. The use of aspirin in unstable angina in the Canadian Aspirin trial was key to establishing the benefit of aspirin in acute coronary syndrome. The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) trial demonstrated that the P2Y12 inhibitor clopidogrel, when added to aspirin, reduced major cardiovascular events. While the use of antiplatelet agents in coronary artery disease antedates the introduction of PCI and remains the cornerstone of secondary prevention of atherosclerotic cardiovascular disease, strategies aiming to optimise their best use are still constantly evolving. In this review, the major randomised trials shaping current clinical practice for the use of aspirin and P2Y12 inhibitors in patients undergoing PCI are summarised, with a focus on aspirin-free strategies and on the role of P2Y12 inhibitor treatment before PCI, two major topics of ongoing investigation that are critical to patient care but that are not addressed in current practice guidelines. Multiple questions remain regarding the use of antiplatelet agents after PCI, including the personalisation of dosing, intensity, pharmacologic formulation, and duration of antiplatelet therapy based on individual patient characteristics and the optimal treatment of patients at high bleeding risk.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet agents may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the benefits and harms of antiplatelet agents in people with any form of CKD, including those with CKD not receiving renal replacement therapy, patients receiving any form of dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 13 July 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet agents versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data were pooled using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 113 studies, enrolling 51,959 participants; 90 studies (40,597 CKD participants) compared an antiplatelet agent with placebo or no treatment, and 29 studies (11,805 CKD participants) directly compared one antiplatelet agent with another. Fifty-six new studies were added to this 2021 update. Seven studies originally excluded from the 2013 review were included, although they had a follow-up lower than two months. Random sequence generation and allocation concealment were at low risk of bias in 16 and 22 studies, respectively. Sixty-four studies reported low-risk methods for blinding of participants and investigators; outcome assessment was blinded in 41 studies. Forty-one studies were at low risk of attrition bias, 50 studies were at low risk of selective reporting bias, and 57 studies were at low risk of other potential sources of bias. Compared to placebo or no treatment, antiplatelet agents probably reduces myocardial infarction (18 studies, 15,289 participants: RR 0.88, 95% CI 0.79 to 0.99, I² = 0%; moderate certainty). Antiplatelet agents has uncertain effects on fatal or nonfatal stroke (12 studies, 10.382 participants: RR 1.01, 95% CI 0.64 to 1.59, I² = 37%; very low certainty) and may have little or no effect on death from any cause (35 studies, 18,241 participants: RR 0.94, 95 % CI 0.84 to 1.06, I² = 14%; low certainty). Antiplatelet therapy probably increases major bleeding in people with CKD and those treated with haemodialysis (HD) (29 studies, 16,194 participants: RR 1.35, 95% CI 1.10 to 1.65, I² = 12%; moderate certainty). In addition, antiplatelet therapy may increase minor bleeding in people with CKD and those treated with HD (21 studies, 13,218 participants: RR 1.55, 95% CI 1.27 to 1.90, I² = 58%; low certainty). Antiplatelet treatment may reduce early dialysis vascular access thrombosis (8 studies, 1525 participants) RR 0.52, 95% CI 0.38 to 0.70; low certainty). Antiplatelet agents may reduce doubling of serum creatinine in CKD (3 studies, 217 participants: RR 0.39, 95% CI 0.17 to 0.86, I² = 8%; low certainty). The treatment effects of antiplatelet agents on stroke, cardiovascular death, kidney failure, kidney transplant graft loss, transplant rejection, creatinine clearance, proteinuria, dialysis access failure, loss of primary unassisted patency, failure to attain suitability for dialysis, need of intervention and cardiovascular hospitalisation were uncertain. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, including prasugrel, ticagrelor, different doses of clopidogrel, abciximab, defibrotide, sarpogrelate and beraprost.

AUTHORS' CONCLUSIONS

Antiplatelet agents probably reduced myocardial infarction and increased major bleeding, but do not appear to reduce all-cause and cardiovascular death among people with CKD and those treated with dialysis. The treatment effects of antiplatelet agents compared with each other are uncertain.

Pharmacological Approaches to Limit Ischemic and Reperfusion Injuries of the Heart. Analysis of Experimental and Clinical Data on P2Y12 Receptor Antagonists

High mortality among people with acute myocardial infarction is one of the most urgent problems of modern cardiology. And in recent years, much attention has been paid to the search for pharmacological approaches to prevent heart damage. In this review, we tried to analyze data on the effect of P2Y₁₂ receptor antagonists on the ischemia/reperfusion tolerance of the heart.

Ischemic and reperfusion injuries of the heart underlie the pathogenesis of acute myocardial infarction (AMI) and sudden cardiac death. The mortality rate is still high and is 5–7% in patients with ST-segment elevation myocardial infarction. The review is devoted to pharmacological approaches to limitation of ischemic and reperfusion injuries of the heart. The article analyzes experimental evidence and the clinical data on the effects of P2Y₁₂ receptor antagonists on the heart’s tolerance to ischemia/reperfusion in animals with coronary artery occlusion and reperfusion and also in patients with AMI. Chronic administration of ticagrelor prevented adverse remodeling of the heart. There is evidence that sphingosine-1-phosphate is the molecule that mediates the infarct-reducing effect of P2Y₁₂ receptor antagonists. It was discussed a role of adenosine in the cardioprotective effect of ticagrelor.

Morphine and Cardiovascular Outcomes Among Patients With Non-ST-Segment Elevation Acute Coronary Syndromes Undergoing Coronary Angiography

BACKGROUND

Mechanistic studies have shown that morphine blunts the antiplatelet effects of oral adenosine diphosphate receptor blockers. However, the clinical relevance of this interaction is controversial.

OBJECTIVES

This study sought to explore the association between morphine and ischemic events in 5,438 patients treated with concomitant clopidogrel presenting with non-ST-segment elevation acute coronary syndromes (NSTEACS) in the EARLY ACS (Early Glycoprotein IIb/IIIa Inhibition in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome) trial. Patients not treated with clopidogrel (n = 3,462) were used as negative controls.

METHODS

Endpoints were the composite of death, myocardial infarction (MI), recurrent ischemia, or thrombotic bailout at 96 h (4-way endpoint) and the composite of death or MI at 30 days.

RESULTS

In patients treated with clopidogrel, morphine use was associated with higher rates of the 4-way endpoint at 96 h (adjusted odds ratio [OR]: 1.40; 95% confidence interval [CI]: 1.04 to 1.87; p = 0.026). There was a trend for higher rates of death or MI at 30 days (adjusted OR: 1.29; 95% CI: 0.98 to 1.70; p = 0.072), driven by events in the first 48 h (adjusted hazard ratio: 1.54; 95% CI: 1.07 to 2.23; p = 0.021). In patients not treated with clopidogrel, morphine was not associated with either the 4-way endpoint at 96 h (adjusted OR: 1.05; 95% CI: 0.74 to 1.49; p = 0.79; p_interaction = 0.36 ) or death or MI at 30 days (adjusted OR: 1.07; 95% CI: 0.77 to 1.48; p = 0.70; p_interaction = 0.46).

CONCLUSIONS

When used concomitantly with clopidogrel pre-treatment, morphine was associated with higher rates of ischemic events in patients with NSTEACS. (EARLY ACS: Early Glycoprotein IIb/IIIa Inhibition in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome; NCT00089895).

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).

Pretreatment with Antiplatelet Agents in the Setting of Percutaneous Coronary Intervention: When and Which Drugs?

Administering antiplatelet agents before coronary angiography to patients referred to elective or urgent percutaneous coronary intervention (PCI) requires a careful evaluation of advantages and disadvantages associated with platelet inhibition to avoid overtreatment on one side and undertreatment on the other. The delicate balance between ischemic protection and bleeding demands the ability to undertake risk stratification and individualized decisions, which is particularly challenging in the setting of ad hoc PCI and urgent procedures. This review analyzes the current evidence on pretreatment with oral and intravenous P2Y₁₂ inhibitors in patients undergoing coronary angiography with intent to undergo PCI.

Identifying psychosocial predictors of medication non-adherence following acute coronary syndrome: A systematic review and meta-analysis

OBJECTIVE

Medication non-adherence following acute coronary syndrome (ACS) is associated with poor clinical outcomes. A systematic review and meta-analysis were undertaken to identify psychosocial factors associated with medication adherence in patients with ACS.

METHODS

A search of electronic databases (Cochrane Library, Medline, EMBASE, PsycINFO, Web of Science, International Pharmaceutical Abstracts, CINAHL, ASSIA, OpenGrey, EthOS and WorldCat) was undertaken to identify relevant articles published in English between 2000 and 2014. Articles were screened against our inclusion criteria and data on study design, sample characteristics, predictors, outcomes, analyses, key findings and study limitations were abstracted.

RESULTS

Our search identified 3609 records, of which 17 articles met our inclusion criteria (15 independent studies). Eight out of ten studies found an association between depression and non-adherence. A meta-analysis revealed that depressed patients were twice as likely to be non-adherent compared to patients without depression (OR=2.00, 95% CI 1.57-3.33, p=0.015). Type D personality was found to predict non-adherence in both studies in which it was measured. Three out of three studies reported that treatment beliefs based on the Necessity-Concerns Framework predicted medication non-adherence and there was some evidence that social support was associated with better adherence. There was insufficient data to meta-analyse all other psychosocial factors identified.

CONCLUSION

There was some evidence that psychosocial factors, particularly depression, were associated with medication adherence following ACS. Targeting depressive symptoms, screening for Type D personality, challenging maladaptive treatment beliefs, and providing better social support for patients may be useful strategies to improve medication adherence.

Reviewing the controversy surrounding pre-treatment with P2Y12 inhibitors in acute coronary syndrome patients

Pretreatment with oral P2Y12 inhibitors occurs each time clopidogrel, prasugrel, ticagrelor are given to patients with suspected coronary artery disease before definition of the coronary anatomy. In acute coronary syndromes, the practice of administering oral P2Y12 inhibitors upstream has been the object of significant controversy in recent years, following the publication of two trials of pretreatment in non-ST-segment elevation acute coronary syndromes and ST-segment elevation myocardial infarction, respectively. The introduction in the market of cangrelor - the first intravenous P2Y12 inhibitor - represents a new opportunity but also a new challenge for clinicians. This article reviews current recommendations and supporting evidence surrounding pretreatment with oral and intravenous P2Y12 inhibitors in patients with acute coronary syndromes.

Bleeding Outcomes Associated with Coronary Artery Bypass Graft Surgery and Recent Clopidogrel Exposure

<p><b>Background:</b> Guidelines recommend discontinuing clopidogrel for at least 5 days before elective coronary artery bypass graft surgery (CABG) to limit blood transfusions and for at least 24 hours before urgent CABG to reduce major bleeding complications. Studies have produced conflicting results regarding whether recent exposure to clopidogrel increases bleeding, the need for intraoperative and postoperative blood products, postoperative complications, and hospital length of stay. We evaluated the effect of clopidogrel exposure on major bleeding at our institution within 5 days of CABG.</p><p><b>Methods:</b> We conducted a retrospective review of patients who underwent CABG at a tertiary academic medical center. The primary outcome was major bleeding, defined as transfusion of 4 units of packed red blood cells (PRBCs) and/or a need for reexploration. Secondary outcomes included non-life-threatening bleeding, defined as transfusion of 2 units but <4 units of PRBCs; postoperative complications; hospital length of stay; readmission within 30 days of the procedure; and hospital mortality. Major bleeding events were analyzed with a logistic regression model that adjusted for covariates of bleeding risk factors.</p><p><b>Results:</b> Of the 715 patients we reviewed, 169 patients received clopidogrel within 5 days before CABG, and 546 patients did not. A significantly higher incidence of major bleeding was observed in the clopidogrel group compared with the group not exposed to clopidogrel (32% versus 17%, <i>P</i> = .002). After adjusting for covariates, patients exposed to clopidogrel had significantly higher odds of major bleeding (odds ratio, 2.1; 95% confidence interval, 1.3-3.4; <i>P</i> = .003). The groups were similar with respect to postoperative complications, except for infection. The clopidogrel-exposed group had a significantly higher rate of leg site infections (3% versus 0.2%, <i>P</i> = .003).</p><p><b>Conclusions:</b> Clopidogrel exposure within 5 days of CABG is associated with an increased risk of major bleeding.</p>

Role of oral factor Xa inhibitors after acute coronary syndrome

Despite an early invasive strategy and the use of dual antiplatelet therapy, patients with acute coronary syndrome (ACS) continue to be at substantial risk for recurrent ischemic events. It is believed that this risk is, at least in part, due to an intrinsic coagulation pathway that remains activated for a prolonged period after ACS. Earlier studies using warfarin showed a reduction in ischemic events, but the overall benefits were offset by increased bleeding complications. Recently, there has been increased interest in the potential role of new oral anticoagulants, some of which target factor Xa, after ACS. Factor Xa is important for the coagulation pathway and also plays a role in cellular proliferation and inflammation. It may thus be an attractive target for therapeutic intervention in ACS. Recently, various oral factor Xa inhibitors have been studied as potential treatment options for ACS. This review will focus on currently available data to evaluate the possible role of factor Xa inhibitors in the management of patients with ACS.

Safety and efficacy of cangrelor, an intravenous, short-acting platelet inhibitor in patients requiring coronary artery bypass surgery

OBJECTIVE

Oral P2Y₁₂ platelet receptor inhibitors are a cornerstone of reducing complications in patients with acute coronary syndromes or coronary stents. Guidelines advocate discontinuing treatment with P2Y₁₂ platelet receptor inhibitors before surgery. Cangrelor, a short-acting, reversible, intravenously administered P2Y₁₂ platelet inhibitor is effective in achieving appropriate platelet inhibition in patients who are awaiting coronary artery bypass grafting (CABG) and require P2Y₁₂ inhibition. The objective of this study was to assess the effects of preoperative cangrelor on the incidence of perioperative complications, which are currently unknown.

METHODS

Patients (n = 210) requiring preoperative clinical administration of thienopyridine therapy were randomized in a multicenter, double-blinded study to receive cangrelor or placebo while awaiting CABG after discontinuation of the thienopyridine. Optimal platelet reactivity, which was defined as <240 P2Y₁₂ platelet reaction units, was measured with serial point-of-care testing (VerifyNow). Pre- and postoperative outcomes, bleeding values, and transfusion rates were compared. To quantify potential risk factors for bleeding, we developed a multivariate logistic model.

RESULTS

The differences between the groups in bleeding and perioperative transfusion rates were not significantly different. The rate of CABG-related bleeding was 11.8% (12/102) in cangrelor-treated patients and 10.4% (10/96) in the placebo group (P = .763). Transfusion rates for the groups were similar. Serious postoperative adverse events for the cangrelor and placebo groups were 7.8% (8/102) and 5.2% (5/96), respectively (P = .454).

CONCLUSIONS

Compared with placebo, bridging patients with cangrelor prior to CABG effectively maintains platelet inhibition without increasing post-CABG complications, including bleeding and the need for transfusions. These data suggest cangrelor treatment is a potential strategy for bridging patients requiring P2Y₁₂ receptor inhibition while they await surgery.

Combined cardioprotectant and antithrombotic actions of platelet P2Y12 receptor antagonists in acute coronary syndrome: just what the doctor ordered

Since the P2Y12 receptor antagonists were first introduced, they have been extensively tested in patients with acute coronary syndrome and are now standard of care. These antiplatelet drugs are very effective in reducing subsequent cardiovascular events, stent thromboses, and mortality in patients with acute myocardial infarction undergoing reperfusion therapy. Although the prevailing view is that their benefit derives from their antithrombotic properties, other unrelated pleiotropic effects appear to be equally beneficial. Accumulating clinical and animal evidence indicates that, if present at the time of reperfusion, these drugs have a direct anti-infarct effect similar to that of ischemic postconditioning. Four oral antagonists have been developed in rapid succession: ticlopidine, clopidogrel, prasugrel, and ticagrelor. Each agent had a more consistent and rapid onset of action than the previous one, and this has correlated with improved clinical outcomes when given early in treatment. Unfortunately, gut absorption causes an appreciable delay in the onset of effect, especially when morphine is used, and the constant push to minimize the door-to-balloon time has made it difficult to achieve adequate platelet inhibition at the time of percutaneous coronary intervention with an oral agent. An intravenous P2Y12 antagonist such as cangrelor may optimize treatment because it produces nearly maximal inhibition of platelet aggregation within minutes. If antiplatelet agents do protect through postconditioning's mechanism, then they would render any other intervention that protects through that mechanism redundant. Indeed, animals treated with cangrelor cannot be further protected by pre- or postconditioning. However, interventions that use a different mechanism such as mild hypothermia or cariporide, a Na(+)-H(+) exchange blocker, do add to cangrelor's protection. Future research should be directed toward identifying interventions that can augment the protection from antiplatelet therapy and finding a way to optimize P2Y12 inhibition at reperfusion in all patients.

Apixaban with antiplatelet therapy after acute coronary syndrome

BACKGROUND

Apixaban, an oral, direct factor Xa inhibitor, may reduce the risk of recurrent ischemic events when added to antiplatelet therapy after an acute coronary syndrome.

METHODS

We conducted a randomized, double-blind, placebo-controlled clinical trial comparing apixaban, at a dose of 5 mg twice daily, with placebo, in addition to standard antiplatelet therapy, in patients with a recent acute coronary syndrome and at least two additional risk factors for recurrent ischemic events.

RESULTS

The trial was terminated prematurely after recruitment of 7392 patients because of an increase in major bleeding events with apixaban in the absence of a counterbalancing reduction in recurrent ischemic events. With a median follow-up of 241 days, the primary outcome of cardiovascular death, myocardial infarction, or ischemic stroke occurred in 279 of the 3705 patients (7.5%) assigned to apixaban (13.2 events per 100 patient-years) and in 293 of the 3687 patients (7.9%) assigned to placebo (14.0 events per 100 patient-years) (hazard ratio with apixaban, 0.95; 95% confidence interval [CI], 0.80 to 1.11; P=0.51). The primary safety outcome of major bleeding according to the Thrombolysis in Myocardial Infarction (TIMI) definition occurred in 46 of the 3673 patients (1.3%) who received at least one dose of apixaban (2.4 events per 100 patient-years) and in 18 of the 3642 patients (0.5%) who received at least one dose of placebo (0.9 events per 100 patient-years) (hazard ratio with apixaban, 2.59; 95% CI, 1.50 to 4.46; P=0.001). A greater number of intracranial and fatal bleeding events occurred with apixaban than with placebo.

CONCLUSIONS

The addition of apixaban, at a dose of 5 mg twice daily, to antiplatelet therapy in high-risk patients after an acute coronary syndrome increased the number of major bleeding events without a significant reduction in recurrent ischemic events. (Funded by Bristol-Myers Squibb and Pfizer; APPRAISE-2 ClinicalTrials.gov number, NCT00831441.).

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.

Treatment and outcomes of first troponin-negative non-ST-segment elevation myocardial infarction

Little is known about non-ST-segment elevation myocardial infarction (MI) in patients with an initial negative troponin finding. The aim of this study was to determine in post hoc analysis of a large regional medical center presenting clinical characteristics, treatment differences, and in-hospital and 6-month outcomes of first troponin-negative MI (FTNMI). In this study, 659 of 1,855 consecutive patients with non-ST-segment elevation MI (35.5%) were classified as having FTNMI. In-hospital cardiac catheterization rates were similar between the 2 groups (70.1% vs 71.5%, p = 0.53) In hospital, patients with FTNMI were less likely to receive statins (48.9% vs 59.9%, p <0.001). On discharge, patients with FTNMI were less likely to be on clopidogrel (53.1% vs 59.0%, p = 0.019) and statins (67.7% vs 75.2%, p <0.001). At 6-month follow-up, patients with FTNMI were less likely to be on clopidogrel (43.5% vs 55.2%, p = 0.01) In-hospital recurrent ischemia was 2 times as common in FTNMI (20.1% vs 11.5%, p <0.001). There were no differences, however, in congestive heart failure, cardiogenic shock, cardiac arrest, stroke, or death in hospital. At 6 months, patients with FTNMI were 2 times as likely to have had recurrent MI (12.0% vs 6.6%, p <0.001). Combined end points of death at 6 months, MI, stroke, and rehospitalization were higher for FTNMI (47.7% vs 40.9%, p = 0.017); however, this was due to higher rates of recurrent MI. In conclusion, patients with FTNMI received less aggressive pharmacotherapy and were 2 times as likely to have recurrent MI at 6 months. FTNMI is common and represents a clinical entity that should be treated more aggressively.

Clinician-patient discord: exploring differences in perspectives for discontinuing clopidogrel

BACKGROUND

Premature stopping of anti-platelet therapy has potentially fatal consequences for myocardial infarction (MI) patients who have received a drug-eluting stent (DES). Exploring multiple perspectives to identify contributing factors to the problem is essential.

AIM

We gained patient and clinician perspectives as to why MI patients prematurely stop anti-platelet therapy (clopidogrel) after DES implantation.

METHODS

This qualitative, descriptive study of DES-treated MI patients (n=22) and of clinicians (physicians and nurse practitioners; n=17) from multiple U.S. cities used content analysis of interview data. Findings across patients and clinicians were then compared to examine congruent and contrasting reasons for premature clopidogrel discontinuance.

FINDINGS

Patients frequently identified communication and education (e.g. unaware they should be taking clopidogrel, unaware of intended duration of therapy) as the primary reasons for having stopped. Patients rarely cited cost, while clinicians most commonly cited cost as a reason for premature stopping.

CONCLUSIONS

The discrepancy in perceptions of patients and clinicians as to the primary reason for early discontinuance suggests an important opportunity for improving persistence. Rather than focusing on the high costs of medications, something outside of their control, physicians should consider communicating more effectively the importance and intended duration of clopidogrel to their patients.

Antiplatelet therapy in percutaneous coronary intervention: a critical review of the 2007 AHA/ACC/SCAI guidelines and beyond

Antiplatelet therapy is a mainstay in the treatment of patients who have undergone percutaneous coronary intervention (PCI). Although the 2007 PCI treatment guidelines were published by the American College of Cardiology, the American Heart Association, and the Society for Cardiovascular Angiography and Interventions, new clinical evidence has emerged, expanding our understanding of antiplatelet use and potentially affecting the treatment guidelines. For example, clinical trial results prompted a Science Advisory to recommend that dual therapy with aspirin and clopidogrel be used for longer periods-up to 1 year in patients who receive bare metal stents and at least 1 year in patients receiving drug-eluting stents. New trial results have also emerged regarding the use of glycoprotein IIb/IIIa antagonists such as abciximab, eptifibatide, and tirofiban. This article reviews the current recommendations for antiplatelet therapy in PCI patients, recent trial results, newly developed agents, ongoing clinical trials, and the future direction of antiplatelet therapy in patients who undergo PCI.

Design and rationale of CURRENT-OASIS 7: a randomized, 2 x 2 factorial trial evaluating optimal dosing strategies for clopidogrel and aspirin in patients with ST and non-ST-elevation acute coronary syndromes managed with an early invasive strategy

BACKGROUND

Antiplatelet therapy with clopidogrel and acetylsalicylic acid (ASA) reduces major cardiovascular events in patients with ST and non-ST-segment-elevation acute coronary syndromes (ACS). Recent mechanistic and clinical data suggest that higher loading and maintenance doses of clopidogrel may achieve a more rapid and greater degree of platelet inhibition that translates into improved clinical outcomes, but this is yet to be formally evaluated in an adequately powered randomized trial.

OBJECTIVES

To evaluate the efficacy and safety of (1) a higher loading and initial maintenance dose of clopidogrel compared with the standard-dose regimen and (2) high-dose ASA compared with low-dose ASA in patients with ST or non-ST-segment-elevation ACS managed with an early invasive strategy.

DESIGN

Multicenter, international, randomized, 2 x 2 factorial design trial evaluating a clopidogrel high-dose regimen (600 mg loading dose on day 1 followed by 150 mg once daily on days 2 to 7, followed by 75 mg once daily on days 8-30) compared with the standard-dose regimen (300 mg loading dose on day 1, followed by 75 mg once daily on days 2-30) and high-dose ASA (300-325 mg daily) versus low-dose ASA (75-100 mg daily) in patients with ST or non-ST-segment-elevation ACS managed with an early invasive strategy. The clopidogrel dose comparison is double-blind and the ASA dose comparison is open-label. The primary outcome is the composite of death from cardiovascular causes, myocardial (re)infarction or stroke up to day 30. The primary safety outcome is major bleeding. The sample size is 18,000 to 20,000 patients.

CONCLUSIONS

The CURRENT-OASIS 7 trial will help to define optimal dosing regimens for clopidogrel and ASA in patients with ST and non-ST-segment-elevation ACS treated with an early invasive strategy.

Impact of pretreatment with clopidogrel on initial patency and outcome in patients treated with primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: a systematic review

BACKGROUND

The main goal of the initial treatment of ST-segment elevation myocardial infarction is prompt reperfusion of the infarct-related artery. The value of pretreatment with clopidogrel before primary percutaneous coronary intervention is currently unclear.

METHODS AND RESULTS

Studies were retrieved through MEDLINE and Cochrane Controlled Trials Register searches over the past 20 years. Two authors independently performed the study selection and data extraction. Randomized controlled studies were included when the research subjects were unselected patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention. Pilot trials, studies that enrolled patients undergoing rescue percutaneous coronary intervention, and studies with angiographic assessment not performed by a core laboratory or 2 blinded investigators were excluded. Thirty-eight treatment groups, including 8429 patients, were included. Initial patency was higher in treatment groups in which patients received pretreatment with clopidogrel (34.3%; 95% confidence interval, 32.9 to 35.8) compared with those in which patients did not receive clopidogrel before initial coronary angiography (25.8%; 95% confidence interval, 24.5 to 27.1). In multivariate-weighted logistic regression analysis, pretreatment with clopidogrel was an independent predictor of early reperfusion (odds ratio, 1.51; 95% confidence interval, 1.31 to 1.74; P<0.0001) and improved clinical outcome.

CONCLUSIONS

Initial patency and clinical outcome were improved in treatment groups that received pretreatment with clopidogrel. These results in patients undergoing primary percutaneous coronary intervention are in line with the experience of pretreatment with clopidogrel in elective patients, non-ST-elevation coronary syndromes, and thrombolytic studies.

Avoiding and Managing Bleeding Complications in Patients with Non-ST-Segment Elevation Acute Coronary Syndromes

Antithrombotic therapy coupled with early use of cardiac catheterization and revascularization have decreased morbidity and mortality rates in patients who have acute ischemic heart disease but who carry a risk for bleeding. Bleeding complications in patients with acute coronary syndromes are associated with worse clinical outcomes, including recurrent ischemic events and death. Determining the appropriate balance between preventing ischemic events and causing bleeding in patients with acute coronary syndromes present a challenging problem for clinicians. Antithrombotics studied in recent clinical trials that have focused on bleeding reduction include bivalirudin and fondaparinux. In this review, the incidence, predictors, and clinical outcomes associated with bleeding are discussed. Furthermore, the association between antithrombotic agents and bleeding and propose strategies to prevent bleeding complications are also discussed.

Efficacy and safety of clopidogrel pretreatment before percutaneous coronary intervention with and without glycoprotein IIb/IIIa inhibitor use

BACKGROUND

Clopidogrel pretreatment before percutaneous coronary intervention (PCI) has been shown to reduce the risk of death and ischemic complications after PCI. However, the need for clopidogrel pretreatment is debated in patients receiving a glycoprotein IIb/IIIa inhibitor (GPI).

METHODS

We performed a collaborative meta-analysis of the results of 3 randomized trials of clopidogrel pretreatment: PCI-CURE, CREDO, and PCI-CLARITY. Patients were stratified based on GPI use at the time of PCI (a postrandomization subgroup analysis). Odds ratios (ORs) and 95% CIs for the effect of clopidogrel pretreatment versus placebo pretreatment on the incidence of cardiovascular death, myocardial infarction (MI), or stroke for up to 30 days after PCI were calculated for each trial within each GPI stratum and were combined using a random effects model.

RESULTS

Six thousand three hundred twenty-five patients were included, 32.4% of whom received a GPI. There was a consistent benefit of clopidogrel pretreatment in reducing the incidence of cardiovascular death, MI, or stroke after PCI both in patients who did not receive a GPI (OR 0.72, 95% CI 0.53-0.98, P = .03) and in those who did (OR 0.69, 95% CI 0.47-1.00, P = .05). There was no evidence of heterogeneity in the benefit of clopidogrel pretreatment between GPI use strata (P = .85 for heterogeneity). Clopidogrel pretreatment was not associated with a significant excess of TIMI major or minor bleeding, either in those who did not receive a GPI (OR 1.20, 95% CI 0.76-1.92) or in those who did (OR 1.22, 95% CI 0.71-2.09) (P = .97 for heterogeneity).

CONCLUSION

Clopidogrel pretreatment before PCI is beneficial and safe regardless of whether a GPI is used at the time of PCI.

Clopidogrel-taking behavior by drug-eluting stent patients: Discontinuers versus continuers

BACKGROUND

Each day, patients make choices whether or not to take their prescribed medications. Previous research has shown that 1 in 7 myocardial infarction (MI) patients discontinued thienopyridines within 1 month of receiving a drug-eluting stent (DES) with serious consequences. This qualitative research study explored in depth the clopidogrel-taking behavior among DES-treated patients who quit taking clopidogrel 1 month after treatment and those who continued therapy.

METHODS

Sequential patients from a prospective MI registry who reported discontinuing clopidogrel within 30 days of DES treatment (N = 11) were matched with continuers (N = 11). Both groups underwent detailed qualitative phone interviews. Coding and thematic representation using directed qualitative content analysis by 3 PhD researchers was done.

RESULTS

Patients were 41-77 years old and the majority was Caucasian and male. Multiple barriers were described by discontinuers that were not reported by continuers. The most frequently cited barrier was misunderstanding the intended duration of treatment. Discontinuers also described system weaknesses that contributed to early discontinuance such as gaps in the transition to primary care.

CONCLUSIONS

While premature discontinuation of a prescribed therapy is viewed by clinicians as a willful disregard for medical advice, early stopping of clopidogrel is influenced greatly by processes of care and system issues.

Bleeding Events with Antithrombotic Therapy in Patients with Unstable Angina or non-ST-segment Elevation Myocardial Infarction; Insights from a Large Clinical Practice Registry (GRACE)

BACKGROUND

Thienopyridine use, in particular clopidogrel in acute coronary syndromes, has been associated with an improvement in outcome. However, little information is available regarding their bleeding risk when used in combination with other antithrombotic agents and revascularisation.

METHODS

In a large, multinational, prospective registry, the Global Registry of Acute Coronary Events, the major bleeding rate (using GRACE criteria) of 27,358 patients with unstable angina or non-ST-elevation myocardial infarction was recorded during index admission. The interaction of thienopyridines on major bleeding with other antithrombotic agents and with revascularisation was analysed.

RESULTS

The 11,478 patients who received thienopyridines during hospitalisation experienced a significant increase in major bleeding (2.8% with thienopyridines, 2.2% without thienopyridines; p=0.002). No significant interaction with glycoprotein IIb/IIIa inhibitors and thienopyridines was seen with regard to bleeding. Thienopyridines with unfractionated heparin did not alter bleeding risk, but thienopyridines with low molecular weight heparin was associated with a significant excess of bleeding (2.1% with thienopyridines, 1.3% without thienopyridines; p=0.004). There was no significant difference in major bleeding with thienopyridines in patients who did or did not undergo revascularisation.

CONCLUSIONS

Major bleeding was increased in patients receiving thienopyridines. No increase in bleeding risk was seen in patients having revascularisation.

Effects of pretreatment with clopidogrel on nonemergent percutaneous coronary intervention after fibrinolytic administration for ST-segment elevation myocardial infarction: a Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis in Myocardial Infarction (CLARITY-TIMI) 28 study

BACKGROUND

The use of routine nonemergent percutaneous coronary intervention (PCI) among patients with ST-segment elevation myocardial infarction (STEMI) after fibrinolytic therapy is unknown. We sought to evaluate the effect of nonemergent PCI on mortality among patients with STEMI treated with fibrinolytic administration and the consequence of clopidogrel pretreatment on this effect.

METHODS

CLARITY-TIMI 28 randomized 3491 patients with STEMI treated with fibrinolytic administration and aspirin to clopidogrel or placebo. All patients were to undergo angiography 48 to 192 hours after randomization. Percutaneous coronary intervention was performed at the discretion of the treating physician. Nonemergent PCI, which was defined as PCI that was not precipitated by recurrent myocardial infarction, was performed in 1781 patients (55.7%).

RESULTS

Nonemergent PCI did not affect 30-day mortality (2.0% vs 2.3% among patients who did not undergo PCI). However, nonemergent PCI was associated with lower mortality among patients randomized to clopidogrel (1.3% vs 2.8%, P = .04) but not among those randomized to placebo (2.6% vs 1.7%, P = .25; interaction P = .025). In multivariate modeling, PCI remained associated with lower mortality among patients randomized to clopidogrel (OR 0.34, 95% CI 0.13-0.92, P = .034) but not placebo (OR 1.41, 95% CI 0.63-3.19, P = .40, interaction P = .028).

CONCLUSION

Among patients with STEMI treated with fibrinolytic administration and aspirin, nonemergent PCI was associated with lower mortality among patients pretreated with clopidogrel. These results suggest that routine nonemergent PCI is beneficial among such patients, although further confirmatory randomized studies are needed.

Optimizing platelet P2Y12 inhibition for patients undergoing PCI

Guidelines recommend that dual antiplatelet therapy using aspirin and clopidogrel should be administered to the majority of patients with acute coronary syndromes, including those undergoing percutaneous coronary intervention (PCI). However, the results of a large randomized, placebo-controlled study suggest that a 300-mg loading dose of clopidogrel must be administered at least 15 h prior to PCI in order to achieve a significant reduction in peri-PCI thrombotic events. Other data suggest that 2 h of pretreatment may be sufficient if a 600-mg loading dose is used. Since it is often difficult to achieve an adequate pretreatment goal with clopidogrel in clinical practice, more rapid achievement of platelet P2Y(12) inhibition may improve patient outcomes. Prasugrel, [6-[2-(3,4-diflurophenyl) cyclopropyl1-1-y1] amino-2-propylthio-9-D-ribofuranosyl-9H-purine (AZD6140), and cangrelor are platelet P2Y(12) receptor antagonists currently in development that offer faster acting inhibition of adenosine diphosphate (ADP)--induced platelet aggregation. These agents act upon the same platelet receptor as clopidogrel, but are distinguished by their routes of administration, reversibility, and pharmacodynamic properties. Prasugrel is an orally administered agent that provides faster, higher, and more consistent inhibition of platelet aggregation than clopidogrel. The results of Phase II testing suggest that the risk of bleeding is similar in prasugrel- and clopidogrel-treated patients. AZD6140 is another orally administered platelet inhibitor with rapid and reversible action. Again, Phase II testing suggests similar bleeding risk for clopidogrel. Preliminary evidence suggests that clinical outcomes may be better in prasugrel- and AZD6140-treated patients than in clopidogrel-treated patients. Cangrelor is an intravenously administered, reversible, short-acting agent with a rapid onset of activity. Bleeding risk and clinical outcomes data are similar in cangrelor- and abciximab-treated patients. The results of ongoing Phase III clinical trials involving more than 40,000 patients will demonstrate whether these agents fulfill their potential to improve outcomes in PCI-treated patients by providing faster, higher, and more consistent inhibition of platelet aggregation.

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.

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.