Dos and Don'ts of Antiplatelet Use for Secondary Stroke Prevention

FEBRUARY 17, 2016
Despite aggressive public health initiatives aimed at curtailing common risk factors like hypertension, diabetes, and hyperlipidemia, stroke remains the fifth-leading cause of death in the United States.
Roughly 80% of all strokes are ischemic in etiology, and thus antiplatelets are the backbone pharmacologic agents for the prevention of recurrent strokes.2 Several antiplatelet agents are available, including aspirin, clopidogrel, and the combination of aspirin and extended-release dipyridamole (Aggrenox). 
The following are the dos and don’ts of antiplatelet use in patients who have experienced an ischemic stroke. 
DO use aspirin as first-line therapy.
Data from meta-regression analysis demonstrate that aspirin therapy produces a 15% relative reduction in the rate of any subsequent stroke in patients with a previous stroke.3 
This benefit was seen across doses ranging from 50 mg/day to 1500 mg/ day, although the risk of toxicity was elevated with higher doses. For patients taking ≤325 mg/day, the risk of serious gastrointestinal hemorrhage was about 0.4% per year. 
Aspirin also costs significantly less than the other available antiplatelet agents. Given the drug’s favorable efficacy, safety, and cost profile, the American Heart Association (AHA) recommends aspirin monotherapy (50-325 mg/day) as initial therapy after a stroke or transient ischemic attack (TIA) for prevention of future stroke (Class I recommendation, level of evidence A).2
DO consider adding clopidogrel to an aspirin regimen early after TIA or minor stroke.
Two recently published trials explored the value of early dual-antiplatelet therapy with aspirin and clopidogrel in the early period after minor stroke and TIA.
While the FASTER trial was terminated early, the larger CHANCE trial demonstrated that this dual therapy significantly reduced the risk of secondary stroke (8.6%) compared with aspirin monotherapy (11.7%).4 Rates of moderate and severe bleeding were similar between groups.
It is worth noting that the therapy was started early (within 24 hours of presentation) and dual therapy was only continued for 21 days. The CHANCE study was also exclusively conducted in China, making extrapolation to other countries difficult. 
In light of these findings, the AHA suggests that the combination of clopidogrel and aspirin might be considered within 24 hours of a minor ischemic stroke or TIA and continued for up to 21 days (Class IIb recommendation, level of evidence B).2

Douglas Jennings, PharmD, FCCP, FAHA
Douglas Jennings, PharmD, FCCP, FAHA
Douglas Jennings, PharmD, FCCP, FAHA, FACC, currently practices as the clinical pharmacy manager in heart transplant and mechanical circulatory support at New York Presbyterian Columbia University Medical Center. He is a past chair of the American College of Clinical Pharmacy (ACCP) Cardiology PRN, and he is a fellow of ACCP, the American Heart Association, and the American College of Cardiology.