ASA failure: does the combination ASA/clopidogrel confer better long-term vascular protection?

Abstract

Objective: To assess whether adding clopidogrel to acetylsalicylic acid (ASA) has a long-term protective vascular effect in patients with lacunar stroke while taking ASA.

Methods: Post hoc analysis of 838 patients with ASA failure and recent lacunar stroke from the Secondary Prevention of Small Subcortical Strokes Trial (SPS3) cohort randomly allocated to aspirin (325 mg/day) and clopidogrel (75 mg/day) or placebo. Primary efficacy outcome was stroke recurrence (ischemic and intracranial hemorrhage) and main safety outcome was major extracranial hemorrhage. Patients were followed for a mean period of 3.5 years.

Results: The ASA failure group had a significantly higher risk of vascular events including ischemic stroke when compared with the non-ASA failure group (n = 2,151) in SPS3 (p = 0.03). Mean age was 65.6 years and 65% were men. The risk of recurrent stroke was not reduced in the dual antiplatelet group, 3.1% per year, compared to the aspirin-only group, 3.3% per year (hazard ratio [HR] 0.91; 95% confidence interval [CI] 0.61-1.37). There was also no difference between groups for ischemic stroke (HR 0.90; 95% CI 0.59-1.38). The risk of gastrointestinal bleeding was higher in the dual antiplatelet group (HR 2.7; 95% CI 1.1-6.9); however, the risk of intracranial hemorrhage was not different.

Conclusions: In patients with a recent lacunar stroke while taking ASA, the addition of clopidogrel did not result in reduction of vascular events vs continuing ASA only.

Classification of evidence: This study provides Class I evidence that for patients with recent lacunar stroke while taking ASA, adding clopidogrel as compared to continuing ASA alone does not reduce the risk of recurrent stroke.

Figure. Probability of the primary outcome (all strokes) for ASA failure and non–ASA failure groups

The hazard ratio for the primary outcome, recurrent stroke, was 0.91 (95% confidence interval [CI] 0.61–1.37) for the acetylsalicylic acid (ASA) failure group and 0.92 (95% CI 0.67–1.24) for the non–ASA failure group.