Atherosclerotic aortic arch debris has been implicated as a risk factor for ischemic stroke. Stroke associated with arch debris afflicts over 100,000 Americans annually, but is has not been established whether arch debris is an independent mechanism of focal cerebral ischemia warranting specific investigation and treatment or simply a marker of generalized atherosclerosis. This large population-based case-control and cohort study will use the resources of the Rochester Epidemiology Project and Mayo Echocardiography Laboratory to: 1) determine whether arch debris is an independent risk factor and mechanism of first focal cerebral ischemia (TIA, ischemic stroke, cryptogenic stroke) independent of evidence of generalized atherosclerosis; and 2) determine the rates of subsequent stroke occurrence among individuals with first focal cerebral ischemia who have arch debris compared to the rates for individuals with first focal cerebral ischemia who have no arch debris. Cases are 510 residents 50 years and older with a biplane or multiplane transesophageal echocardiogram (TEE) performed to evaluate a first ischemic stroke or TIA from 1993-99. The multiple logistic models of the case-control study analyses will be repeated with and without controlling for generalized atherosclerosis and using two different types of controls without stroke or TIA: 1) 1000 residents 50 years and older with a biplane or multiplane TEE performed for clinical indications other than stroke or TIA; and 2) 560 randomly selected residents who had a biplane or multiplane TEE for the SPARC study. The ratio of the odds of first focal cerebral ischemia for those with arch debris to the odds for those without arch debris derived with and without controlling for evidence of generalized atherosclerosis and using the two different types of controls will be compared. The investigators note that the study will therefore not only determine whether arch debris is a risk factor for first focal cerebral ischemia independent of atherosclerosis in general, but will also test different approaches to the design of population-based case-control studies. The cohort study of 570 individuals of all ages with first focal cerebral ischemia will compare the Kaplan-Meier estimates of survival free of subsequent stroke for those who have arch debris to those who do not, and the proportional hazards model will determine whether arch debris is an independent determinant of subsequent stroke adjusting for confounding variables, including age and evidence of generalized atherosclerosis. The investigators state that the study will also determine if clinical trials aimed at primary and secondary stroke prevention in these patients are warranted, and if so, assist in their design.
