Guidelines are written and presented in a modular knowledge chunk format, in which each chunk includes a table of recom- mendations, a brief synopsis, recommendation-specific supportive text, and, when appropriate, flow diagrams or additional tables. Hyperlinked references are provided for each modular knowledge chunk to facilitate quick access and review. Other modifications to the guidelines include the addition of Knowledge Gaps and Future Research segments in some sections and a web guideline supple- ment (Data Supplement) for useful but noncritical tables and figures. Sepideh Amin-Hanjani, MD, FAHA Immediate Past Chair, AHA Stroke Council Scientific Statement Oversight Committee Joseph P. Broderick, MD, FAHA Chair, AHA Stroke Council Scientific Statement Oversight Committee Each year, 795000 individuals in the United States experience a stroke, of which 87% (690000) are isch- emic and 185000 are recurrent.1 individuals experience a transient ischemic attack (TIA) The risk of recurrent stroke or TIA is high but can be mitigated with appropriate secondary stroke *The American Stroke Association is a division of the American Heart Association. CLINICAL STATEMENTS AND GUIDELINES Kleindorfer prevention. In fact, cohort studies have shown a reduc- tion in recurrent stroke and TIA rates in recent years as secondary stroke prevention strategies have improved.3,4 A meta-analysis of randomized controlled trials (RCTs) of secondary stroke prevention therapies published from 1960 to 2009 showed a reduction in annual stroke recurrence from 8.7% in the 1960s to 5.0% in the 2000s, with the reduction driven largely by improved blood pressure (BP) control and use of antiplatelet ther- The changes may have been influenced by changes in diagnostic criteria and differing sensitivities of diag- nostic tests over the years. The overwhelming majority of strokes can be pre- vented through BP control, a healthy diet, regular physi- cal activity, and smoking cessation. 