The incidence of ischemic stroke in the United States is estimated to be more than 795,000 events each year.1 After an initial stroke, the rate of recurrence is 5% to 20% within the first year, with the greatest prevalence in the first 90 days following an event.2-5 Although dual antiplatelet therapy, often with aspirin and a P2Y12 inhibitor such as clopidogrel, reduces the risk for recurrent cardiovascular events, cerebrovascular events, and death following acute coronary syndromes and percutaneous intervention, the role of combination antiplatelet therapy for secondary prevention of ischemic stroke continues to be debated.6 Reconciling currently available data can be challenging, as many studies vary considerably in both the time to antiplatelet initiation and duration of therapy.
For many years, aspirin alone was the drug of choice for secondary prevention of noncardioembolic ischemic stroke.7 Efficacy is similar at dosages anywhere between 50 and 1500 mg/d; higher doses incur a greater risk for gastrointestinal hemorrhage.7 Current secondary prevention guidelines recommend a dosage of aspirin somewhere between 50 and 325 mg/d.7
Alternative agents have also been evaluated for secondary stroke prevention, but only clopidogrel is currently considered an acceptable alternative for monotherapy based on a subgroup analysis of the CAPRIE (Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events) trial.7,8 Other alternatives, including cilostazol, ticlopidine, and ticagrelor, are limited by a lack of data, adverse drug reactions, or unproven efficacy and are not recommended in current guidelines.7,9 The ongoing THALES (Acute Stroke or Transient Ischaemic Attack Treated with Ticagrelor and Aspirin for Prevention of Stroke and Death) trial, assessing combination ticagrelor and aspirin, may identify an additional option for antiplatelet therapy following acute stroke.10
The current guidelines from the American Heart Association/American Stroke Association (AHA/ASA) support the combination of aspirin and extended-release dipyridamole (ASA-ERDP) as a long-term alternative to aspirin monotherapy.7,11 Additionally, the combination of clopidogrel and aspirin (CLO-ASA) is now recommended for limited duration in the early management of ischemic stroke.11
This review will explore the role of dual antiplatelet therapy for secondary prevention of noncardioembolic ischemic stroke or transient ischemic attack (TIA), with particular focus on acute use of CLO-ASA.
Clopidogrel and aspirin: When to initiate, when to stop
The combined use of clopidogrel and aspirin has been well-studied for secondary prevention of ischemic stroke and TIA. However, interpreting and applying the results of these trials can be challenging given key differences in both time to treatment initiation and the duration of combination therapy. Highlights of the major randomized controlled trials (RCTs) evaluating the safety and efficacy of CLO-ASA are detailed in TABLE 1.4,5,12-15
Initial trials evaluating CLO-ASA for secondary stroke prevention, including the MATCH (Management of ATherothrombosis with Clopidogrel in High-risk patients),12 SPS3 (Secondary Prevention of Small Subcortical Strokes),13 and CHARISMA (Clopidogrel for High Atherothrombotic Risk and Ischaemic Stabilization, Management and Avoidance)14 trials assessed the long-term benefits of combination therapy, with most patients initiating treatment a month or more following an initial stroke and continuing therapy for at least 18 months.12-14 Results from these trials indicate that long-term use (> 18 months) of CLO-ASA does not reduce recurrent events but increases rates of clinically significant bleeding.12-14
Continue to: A look at Tx timing