Kaplan-Meier estimates of the probability of remaining stroke-free among patients receiving transfusion and patients on standard care. The P value was calculated by log-rank test. Tick marks indicate the lengths of observation of patients who did not have a stroke. Four patients were not included in this analysis: 1 patient from the standard care group who experienced intracerebral hematoma as noted on baseline MRI, and 3 patients who developed stroke after change in treatment during the posttrial follow-up (2 from the standard care and 1 from the transfusion group).