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What Is The CHA..

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Transient ischemic attacks (TIAs) and minor strokes are associated with subsequent risk of stroke especially within the first 3 months.1 The role of dual antiplatelet therapy (clopidogrel and aspirin) for secondary stroke prevention has been studied in several trials, including the MATCH trial and the SPS3 trial.2,3 Dual therapy in both trials was not found to significantly reduce the risk of recurrent strokes and increased the risk of bleeding.2,3 Based on the results of these trials, the American Heart Association and the American Stroke Association guidelines for stroke prevention recommend avoiding this combination for secondary prophylaxis.4 However, the role of combination therapy during the high-risk period immediately following a TIA or minor strokes has not been studied. Therefore, the CHANCE trial (Clopidogrel in High risk patients with Acute Nondisabling Cerebrovascular Events) was designed to see if clopidogrel and aspirin can be effective when initiated early compared to aspirin monotherapy.1

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The CHANCE trial was a randomized, double-blind, double-dummy, placebo-controlled trial conducted at 114 centers in China. Patients were randomized into two groups within 24 hrs after a TIA or minor stroke. The treatment arms were divided into two groups, clopidogrel and aspirin or aspirin alone, for 3 months. On day 1, both groups received aspirin (dose range of 75-300 mg). Patients that received combination therapy received a loading dose of 300 mg of clopidogrel on day 1, with 75 mg per day from days 2- 90 and aspirin 75 mg daily for days 2-21 and placebo aspirin for days 22-90. The aspirin group received a placebo version of clopidogrel from day 1-90 and 75 mg aspirin from days 2-90. The inclusion criteria consisted of patients who were 40 years of age or older and diagnosed with a minor acute ischemic stroke or high-risk TIA and the ability to start the drug therapy within 24 hrs after symptom onset. Patients were excluded from the study if they had active bleeding, were at high risk of bleeding, had an indication to receive anticoagulation, long-term requirement of non-study antiplatelet agents or NSAIDs, or contraindications to study medications. The primary efficacy outcome was the appearance of a new stroke (ischemic or hemorrhagic) within 90 days. The secondary efficacy outcome was a composite of new clinical vascular events (ischemic stroke, hemorrhagic stroke, MI, or vascular death). The primary safety outcome of this trial was moderate-to-severe bleeding events using the GUSTO criteria. Severe hemorrhage was defined as intracranial hemorrhage or hemorrhage, which required blood transfusions, while moderate bleeding was defined as bleeding requiring a transfusion of blood but without hemodynamic compromise requiring intervention.1

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The overall patient sample had a median age of 62 years and was well-matched; 27.9% of the patients had a TIA with a median time to randomization of 13 hours. Patients on dual antiplatelet therapy had a lower stroke event of 8.2% compared to aspirin monotherapy, which had an event rate of 11.7% (HR 0.68, CI, 0.57-0.81, p <0.01). Similar results were found in individuals with a TIA or minor stroke. New vascular events also favored combination therapy (HR 0.69, CI, 0.58-0.82, p <0.001). Both combination therapy and aspirin had similar rates of moderate to severe bleeding (0.3% in both groups). However, the rate of overall bleeding events was higher in the combination group compared to the aspirin group (2.3% vs. 1.6%) but did not reach statistical significance (HR 1.41, CI, 0.95- 2.10; P= 0.09).1...

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