Rationale and design of ACTIVE: the atrial fibrillation clopidogrel trial with irbesartan for prevention of vascular events.

BACKGROUND: Atrial fibrillation (AF) is the most frequently occurring cardiac arrhythmia with often serious clinical consequences. Many patients have contraindications to anticoagulation, and it is often underused in clinical practice. The addition of clopidogrel to aspirin (ASA) has been shown to reduce vascular events in a number of high-risk populations. Irbesartan is an angiotensin receptor-blocking agent that reduces blood pressure and has other vascular protective effects. METHODS AND RESULTS: ACTIVE W is a noninferiority trial of clopidogrel plus ASA versus oral anticoagulation in patients with AF and at least 1 risk factor for stroke. ACTIVE A is a double-blind, placebo-controlled trial of clopidogrel in patients with AF and with at least 1 risk factor for stroke who receive ASA because they have a contraindication for oral anticoagulation or because they are unwilling to take an oral anticoagulant. ACTIVE I is a partial factorial, double-blind, placebo-controlled trial of irbesartan in patients participating in ACTIVE A or ACTIVE W. The primary outcomes of these studies are composites of vascular events. A total of 14000 patients will be enrolled in these trials. CONCLUSIONS: ACTIVE is the largest trial yet conducted in AF. Its results will lead to a new understanding of the role of combined antiplatelet therapy and the role of blood pressure lowering with an angiotensin II receptor blocker in patients with AF.

Clopidogrel plus aspirin versus oral anticoagulation for atrial fibrillation in the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W): a randomised controlled trial.

BACKGROUND: Oral anticoagulation therapy reduces risk of vascular events in patients with atrial fibrillation. However, long-term monitoring is necessary and many patients cannot achieve optimum anticoagulation. We assessed whether clopidogrel plus aspirin was non-inferior to oral anticoagulation therapy for prevention of vascular events. METHODS: Patients were enrolled if they had atrial fibrillation plus one or more risk factor for stroke, and were randomly allocated to receive oral anticoagulation therapy (target international normalised ratio of 2.0-3.0; n=3371) or clopidogrel (75 mg per day) plus aspirin (75-100 mg per day recommended; n=3335). Outcome events were adjudicated by a blinded committee. Primary outcome was first occurrence of stroke, non-CNS systemic embolus, myocardial infarction, or vascular death. Analyses were by intention-to-treat. This study is registered with ClinicalTrials.gov, number NCT00243178. RESULTS: The study was stopped early because of clear evidence of superiority of oral anticoagulation therapy. There were 165 primary events in patients on oral anticoagulation therapy (annual risk 3.93%) and 234 in those on clopidogrel plus aspirin (annual risk 5.60%; relative risk 1.44 (1.18-1.76; p=0.0003). Patients on oral anticoagulation therapy who were already receiving this treatment at study entry had a trend towards a greater reduction in vascular events (relative risk 1.50, 95% CI 1.19-1.89) and a significantly (p=0.03 for interaction) lower risk of major bleeding with oral anticoagulation therapy (1.30; 0.94-1.79) than patients not on this treatment at study entry (1.27, 0.85-1.89 and 0.59, 0.32-1.08, respectively). CONCLUSION: Oral anticoagulation therapy is superior to clopidogrel plus aspirin for prevention of vascular events in patients with atrial fibrillation at high risk of stroke, especially in those already taking oral anticoagulation therapy.

Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation.

BACKGROUND: Despite current treatments, patients who have acute coronary syndromes without ST-segment elevation have high rates of major vascular events. We evaluated the efficacy and safety of the antiplatelet agent clopidogrel when given with aspirin in such patients. METHODS: We randomly assigned 12,562 patients who had presented within 24 hours after the onset of symptoms to receive clopidogrel (300 mg immediately, followed by 75 mg once daily) (6259 patients) or placebo (6303 patients) in addition to aspirin for 3 to 12 months. RESULTS: The first primary outcome--a composite of death from cardiovascular causes, nonfatal myocardial infarction, or stroke--occurred in 9.3 percent of the patients in the clopidogrel group and 11.4 percent of the patients in the placebo group (relative risk with clopidogrel as compared with placebo, 0.80; 95 percent confidence interval, 0.72 to 0.90; P<0.001). The second primary outcome--the first primary outcome or refractory ischemia--occurred in 16.5 percent of the patients in the clopidogrel group and 18.8 percent of the patients in the placebo group (relative risk, 0.86; 95 percent confidence interval, 0.79 to 0.94; P<0.001). The percentages of patients with in-hospital refractory or severe ischemia, heart failure, and revascularization procedures were also significantly lower with clopidogrel. There were significantly more patients with major bleeding in the clopidogrel group than in the placebo group (3.7 percent vs. 2.7 percent; relative risk, 1.38; P=0.001), but there were not significantly more patients with episodes of life-threatening bleeding (2.2 percent [corrected] vs. 1.8 percent; P=0.13) or hemorrhagic strokes (0.1 percent vs. 0.1 percent). CONCLUSIONS: The antiplatelet agent clopidogrel has beneficial effects in patients with acute coronary syndromes without ST-segment elevation. However, the risk of major bleeding is increased among patients treated with clopidogrel.

Effects of pretreatment with clopidogrel and aspirin followed by long-term therapy in patients undergoing percutaneous coronary intervention: the PCI-CURE study.

BACKGROUND: Despite the use of aspirin, there is still a risk of ischaemic events after percutaneous coronary intervention (PCI). We aimed to find out whether, in addition to aspirin, pretreatment with clopidogrel followed by long-term therapy after PCI is superior to a strategy of no pretreatment and short-term therapy for only 4 weeks after PCI. METHODS: 2658 patients with non-ST-elevation acute coronary syndrome undergoing PCI in the CURE study had been randomly assigned double-blind treatment with clopidogrel (n=1313) or placebo (n=1345). Patients were pretreated with aspirin and study drug for a median of 6 days before PCI during the initial hospital admission, and for a median of 10 days overall. After PCI, most patients (>80%) in both groups received open-label thienopyridine for about 4 weeks, after which study drug was restarted for a mean of 8 months. The primary endpoint was a composite of cardiovascular death, myocardial infarction, or urgent target-vessel revascularisation within 30 days of PCI. The main analysis was by intention to treat. FINDINGS: There were no drop-outs. 59 (4.5%) patients in the clopidogrel group had the primary endpoint, compared with 86 (6.4%) in the placebo group (relative risk 0.70 [95% CI 0.50-0.97], p=0.03). Long-term administration of clopidogrel after PCI was associated with a lower rate of cardiovascular death, myocardial infarction, or any revascularisation (p=0.03), and of cardiovascular death or myocardial infarction (p=0.047). Overall (including events before and after PCI) there was a 31% reduction cardiovascular death or myocardial infarction (p=0.002). There was less use of glycoprotein IIb/IIIa inhibitor in the clopidogrel group (p=0.001). At follow-up, there was no significant difference in major bleeding between the groups (p=0.64). INTERPRETATION: In patients with acute coronary syndrome receiving aspirin, a strategy of clopidogrel pretreatment followed by long-term therapy is beneficial in reducing major cardiovascular events, compared with placebo.