Nearly a quarter of Americans who have a stroke have had one previously. That’s about 185,000 people who experience recurrent stroke in the average year. The most important step in preventing recurrent stroke is initiating antiplatelet therapy in all patients who have had a stroke or transient ischemic attack (TIA), which reduces the risk by 22%, according to a recent article in the American Family Physician (AFP). Despite the clear benefit, nearly one-third of patients will stop taking antiplatelet therapy.
Pharmacists can play a key role in helping patients continue their medications as prescribed. A meta-analysis of 29 studies found that the most common factors for discontinuation were treatment concerns, lack of support with medication intake, and challenges with multiple medications—all of which pharmacists can address.
According to the AFP article, “the selection of antiplatelet therapy should be based on timing, safety, effectiveness, cost, patient characteristics, and patient preference.” The FDA has approved three antiplatelet therapies for secondary stroke prevention: aspirin, clopidogrel, and an aspirin/dipyridamole combination. Discussing the advantages, side effects, and other concerns associated with each of these can boost patient adherence.
Aspirin is the first choice for therapy, but it may cause gastrointestinal bleeding and the risk rises with the dose. For patients with allergies to aspirin, the authors recommend clopidogrel. Both agents have comparable rates of gastrointestinal upset. Using aspirin and clopidogrel together is not advised for more than 2 or 3 years, as the combination substantially elevates the risk of major or life-threatening bleeding without improving effectiveness. Proton pump inhibitors decrease the effectiveness of clopidogrel, and a histamine H2 blocker or pantoprazole should be used instead in patients with gastroesophageal reflux disease (GERD).
The aspirin/dipyridamole combination appears to be at least as effective as aspirin alone, but a quarter of patients experience headache with it. The combination also increases the risk of intracranial and extracranial hemorrhage.
The authors do not recommend vitamin K antagonists such as warfarin for prevention of most recurrent ischemic strokes because of their increased risk of bleeding compared to antiplatelet therapy.
For the 15% of patients who have had ischemic strokes caused by atrial fibrillation, however, the American Heart Association, American College of Cardiology, and the European Society of Cardiology recommend the use of anticoagulants, whether vitamin K antagonists or direct oral anticoagulants such as dabigatran, apixaban, edoxaban, or rivaroxaban. The American College of Neurology recommends use of anticoagulants in patients who have had transient ischemic attacks as well. The oral medications apixaban, dabigatran, edoxaban, and rivaroxaban have all been demonstrated to prevent stroke as well or better than warfarin and to pose a lower risk of intracranial hemorrhage.
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