Question 3

those who have had an acute myocardial infarction or stent placement

Correct.  Several studies have shown that, as compared to aspirin alone, dual antiplatelet therapy reduces the risk of cardiovascular events in patients with acute coronary syndromes, including acute myocardial infarction and percutaneous coronary intervention (PCI).

those with a recent stroke

Incorrect.  In patients with recent stroke, clopidogrel or aspirin plus dipyridamole both appear effective for the prevention of recurrent vascular events.  As compared to these therapies, clopidogrel plus aspirin does not appear to substantially reduce the rate of ischemic events in patients with a prior ischemic stroke, but does increase bleeding risk.  Combination clopidogrel plus aspirin is generally not recommended to reduce ischemic events in patients witha recent stroke.

those without coronary artery disease but with multiple coronary risk factors

Incorrect. The CHARISMA trial found no additional benefit of adding clopidogrel to aspirin for primary prevention of cardiovascular events in patients with multiple vascular risk factors.

those with atrial fibrillation who are candidates for anticoagulation with warfarin

Incorrect.  As compared to dual antiplatelet therapy in patients with atrial fibrillation, warfarin plus a single antiplatelet therapy reduces the rate of cardiovascular events withonly a slight increase in major bleeding risk. Further, the WOEST trial, which compared multiple treatment strategies in patients with atrial fibrillation, found that compared to warfarin plus a single antiplatelet agent, triple therapy (i.e., warfarin and dual antiplatelet therapy) did not further reduce the risk of thromboembolic events, though it did increase the risk of bleeding events.