Mechanisms of ischemic stroke in HIV-infected patients

Objective: To evaluate the types and mechanisms of stroke in a large population of HIV-infected patients. Methods: We reviewed records of consecutive HIV-infected patients with acute stroke admitted to a large metropolitan hospital between 1996 and 2004. Stroke mechanism was defined by consensus between two cerebrovascular neurologists using TOAST classification. Results: A total of 82 patients were included, 77 with ischemic stroke and 5 with intracerebral hemorrhage. Mean age was 42 years and 89% were African American. Previous diagnosis of HIV infection was documented in 91% and AIDS diagnosis in 80%. Mean CD4 count was 113 cells/mm(3) and 85% had CD4 count < 200 cells/mm(3). A total of 61% of patients had received combination antiretroviral treatment (CART). The mechanism of ischemic stroke was large artery atherosclerosis in 12%, cardiac embolism in 18%, small vessel occlusion in 18%, other determined etiology in 23%, and undetermined in 29% (including 19% with incomplete evaluation). Vasculitis was deemed responsible for the stroke in 10 patients (13%) and hypercoagulability in 7 (9%). Protein S deficiency was noted in 10/22 (45%) and anticardiolipin antibodies in 9/31 (29%) tested patients. When comparing patients with large or small vessel disease (atherothrombotic strokes) vs the rest of the population, there were no differences in exposure to CART or CD4 count, but patients with non-atherothrombotic strokes were younger (p = 0.04). Recent cocaine exposure was less common among patients with atherothrombotic strokes (p = 0.02). Strokes were fatal or severely disabling in 35% of cases. Conclusions: Stroke mechanisms are variable in HIV-infected patients, with a relatively high incidence of vasculitis and hypercoagulability. In our population of severely immunodepressed patients, exposure to combination antiretroviral treatment did not significantly influence the mechanism of stroke.