Inherited Hypercoagulable State: Treatment for Primary Prevention of Stroke There is very little evidence to guide the management of asymptomatic people with thrombophilia. A systematic review of prospective observational studies indicated that most venous thromboembolic events occurred during periods of high risk such as surgery, trauma, or pregnancy.834 These studies and expert opinion suggest that antithrombotic pro- phylaxis during these periods would be likely to be effec- However, the effect of prophylaxis on the incidence of stroke or TIA in these subjects is not known. Hypercoagulability: Summary and Gaps Inherited and acquired hypercoagulable states are associated with venous thrombosis, but their association with arterial cerebral infarction is uncertain. Young women with isch- emic stroke have a higher prevalence of aPL. The majority of case-control studies have not found an association between acquired or hereditary hypercoagulable states and stroke in other patient populations. The relationship between the pres- ence of PFO and thrombophilia deserves further study because it may affect primary and secondary stroke prevention strate- gies. Large prospective studies should be undertaken to refine the risks and to establish the associations of thrombophilias with venous thromboembolism and first ischemic stroke. Although the pathogenic role of prothrombotic abnormalities in childhood and young adult ischemic stroke is increasingly becoming evident, the lack of any clinical trial data precludes definitive recommendations for screening or treatment. Hypercoagulability: Recommendations 1. The usefulness of genetic screening to detect inher- ited hypercoagulable states for the prevention of first stroke is not well established (Class IIb; Level of Evidence C). 2. The usefulness of specific treatments for primary stroke prevention in asymptomatic patients with a hereditary or acquired thrombophilia is not well established (Class IIb; Level of Evidence C). 3. 