There is an ongoing primary prevention trial of warfarin therapy (INR, 2.0 2.5) to decrease thromboembolic events in patients with lupus and aPL.825 The Antiphospholipid Antibody Acetylsalicylic Acid (APLASA) study was a small, multicenter, double-blind, pla- cebo-controlled trial for the primary prevention of thrombosis in asymptomatic patients who were persistently aPL positive that compared low-dose aspirin (81 mg/d; n=48) with placebo (n=50) over an average follow-up of 2.30 0.95 years.816 The rates of acute thrombosis were 2.75 per 100 patient-years for the aspirin-treated subjects and 0 per 100 patient-years for placebo- sample size was relatively small; thus, the study insufficiently powered. A parallel and separate observational study published within the APLASA study816 found no reduction in the rate of first thrombotic events with low-dose (81 mg/d) aspirin over placebo in persistently aPL-positive asymptomatic individuals. These individuals also appeared to have a low overall annual incidence rate of acute thrombosis and often developed vascular events in the setting of additional thrombotic risk factors. Inherited Hypercoagulable State: Relationship to Ischemic Stroke Inherited hypercoagulable states that have been associated with stroke include fibrinogen level, the -chain 455 G/A fibrinogen, factor VIII levels, factor XIII Val34Leu, von Willebrand factor small polymorphism in intron 2, tissue-type plasminogen activator 7351 C/T, thrombotic thrombocyto- penic purpura, and heparin-induced thrombocytopenia.826 The majority of case-control studies have not found an association between arterial stroke and other hereditary hypercoagulable states such as factor V Leiden or prothrombin 20210 muta- tions or deficiencies of protein C, protein S, or antithrom- One study suggests that hypercoagulable states may be more frequent in stroke patients with PFO compared with those without PFO. That study found no difference in the prevalence of either the factor V Leiden mutation or the pro- thrombin 20210 mutation in patients with cryptogenic strokes compared with control subjects. 