Lp(a): Summary and Gaps Elevated Lp(a) is associated with a higher risk of stroke. Although niacin lowers Lp(a), randomized trials have not showed that niacin supplementation lowers the risk of stroke. Elevated Lp(a): Recommendations 1. The use of niacin, which lowers Lp(a), might be reasonable for the prevention of ischemic stroke in patients with high Lp(a), but its effectiveness is not well established (Class IIb; Level of Evidence B). 2. The clinical benefit of using Lp(a) in stroke risk pre- diction is not well established (Class IIb; Level of Evidence B). Hypercoagulability The acquired and hereditary hypercoagulable states (thrombo- philias) are associated with venous thrombosis, but a relation- ship with arterial cerebral infarction is based largely on case series or case-control studies. Of these, the presence of aPLs, generally an acquired condition, is most strongly associated with arterial thrombosis. aCL (more prevalent but less spe- cific) and lupus anticoagulant (less prevalent but more spe- cific) are most frequently used to detect aPLs. Retrospective and prospective studies suggested an association between aCL and first ischemic stroke.814,815 From limited, often uncon- trolled data that include predominantly patients with SLE and potentially other vascular risk factors that are poorly detailed, asymptomatic patients with aPL are estimated to have a 0% to Acquired Hypercoagulable State: Relationship to Ischemic Stroke Case-control studies of aPL in young stroke patients have uni- formly demonstrated an association, as have most studies of unselected stroke populations. However, this is not the case for case-control studies among older adults with ischemic stroke. The Sneddon syndrome was formerly thought to be a manifes- tation of aPL syndrome, but it may be present in patients with or without aPLs,817 and the risk of ischemic stroke is increased only in those patients with increased aPLs. 