BACKGROUND:

Although angiographic evidence of coronary atherosclerosis is one of the best predictors of clinical events, non-invasive imaging of this arterial bed is not yet possible. The availability of non-invasive methods for imaging the carotid arteries, and the intra-individual similarity of extent of disease in the coronary and carotid arteries provides rationale for this study that assesses the usefulness of B-mode ultrascan evaluation of extracranial carotid artery atherosclerosis as an independent predictor of clinical sequelae such as fatal and non-fatal myocardial infarction and stroke.

DESIGN NARRATIVE:

Pilot data from an ongoing case-comparison study of risk factors for coronary and carotid atherosclerosis as defined by angiography and B-mode ultrasound provided a background for this project. Patients from the pilot study were used in this study. Beginning in 1986, traditional risk factors such as lipids, lipoproteins, blood pressure, diabetes, and smoking were measured as were non-traditional risk factors such as apolipoproteins and genetic markers. The cohort was followed for 3.5 to 8.5 years for incidence of clinical events. Multivariate techniques were used to relate disease or risk factor status to all-cause mortality, fatal and non-fatal myocardial infarction, and fatal and non-fatal stroke. The same subjects were re-evaluated periodically by B-mode for extent of carotid atherosclerosis. A fifty percent random sample of patients positive for both cerebrovascular disease and coronary artery disease and a fifty percent random sample of patients negative for both cerebrovascular disease and coronary artery disease had repeat B-mode measurements at 2.5 years. All patients surviving at the end of five years had repeat B-mode scans.

The study was renewed in 1996 through April 1999 to conduct a longitudinal study testing the following hypotheses: 1.) Incidence of cardiovascular events (bypass surgery, angioplasty, fatal and non-fatal myocardial infarction, and stroke and endarterectomy) in men and women with extensive carotid wall thickening (CWT) at baseline exceeds that of those with less extensive baseline carotid wall thickening; the relation of carotid wall thickening to outcome is independent of coronary artery disease and/or coronary artery disease risk factors; and, 2.) carotid wall thickening progresses more rapidly in males and females with coronary artery disease and/or coronary artery disease risk factors than in coronary artery disease/risk factor free controls.

The investigators intend to: 1) follow-up a cohort of 670 individuals with defined coronary anatomy, extent of carotid wall thickening, and coronary artery disease risk factors over 5-10 years for fatal and non-fatal cardiovascular events. Coronary artery disease, carotid wall thickening, and coronary artery disease risk factor status at accession will be related to outcome; and, 2.) In a separate (new) cohort of 280 volunteers with and without coronary artery disease they will evaluate carotid wall thickening yearly for three years, and use multivariable analysis to relate accession status to progression rate. Availability of a unique sample of patients largely already characterized for coronary status (at angiography), coronary artery disease risk factors, and carotid wall thickening, and development of B-mode methods for quantifying carotid wall thickening and biostatistical approaches for quantifying progression of carotid wall thickening over a short time span (three years) provide opportunity for this project. Recent pilot data support its feasibility.