CONCLUSION AND RELEVANCE: The findings of this cohort study suggest that in patients with TIA and minor ischemic stroke, the coexistence of atherosclerosis, SVD, cardiac pathology, dissection, or other causes is substantial, and the 5-year risk of a major vascular event varies considerably across the 5 categories of underlying diseases. These findings further suggest the need for secondary prevention strategies based on pathophysiology rather than a one-size-fits-all …