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Mayo Clin Proc. 1999 Sep;74(9):862-9.

Prevalence of potential risk factors for stroke assessed by transesophageal echocardiography and carotid ultrasonography: the SPARC study. Stroke Prevention: Assessment of Risk in a Community.

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Department of Neurology, Mayo Clinic Rochester, Minn 55905, USA.



The SPARC (Stroke Prevention: Assessment of Risk in a Community) study was designed to identify risk factors for stroke and cardiovascular disease using transesophageal echocardiography and carotid ultrasonography. This protocol was undertaken to establish a cohort in which putative risk factors for stroke were identified so that subsequent follow-up could discern the roles these risk factors play in stroke incidence.


This was a prospective, population-based study. A randomly selected cohort comprised 1475 Olmsted County, Minnesota, residents aged 45 years or older, of whom 588 agreed to participate. Transesophageal echocardiography and carotid ultrasonography were used for evaluation of the subjects. Prevalences of various cardiovascular and cerebrovascular conditions were determined.


Transesophageal echocardiography was successfully completed in 581 subjects. The prevalence (+/-SE) of patent foramen ovale was 25.6% (+/-1.9%), and that of atrial septal aneurysm was 2.2% (+/-0.6%). The prevalence of aortic atherosclerosis increased with age and was most common in the descending aorta, particularly in subjects 75 to 84 years old. The prevalence of strands on native valve was 46.4% (+/-2.2%). Carotid ultrasonography data for 567 participants revealed minimal atherosclerotic disease. Most subjects had minimal or mild carotid occlusive disease. The prevalence of moderate (50%-79%) and severe (80%-99%) stenosis was 7.7% (+/-1.1%) and 0.3% (+/-0.2 %), respectively.


This prospective study defines the prevalence of multiple potential cardiovascular and cerebrovascular risk factors, providing population-based data for ongoing follow-up of the risk of stroke.

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