Association between carotid artery bifurcation disease and risk factors for atherosclerosis

Patients referred to the vascular laboratory for carotid duplex scanning may have identifiable risk factors for atherosclerosis. The presence of these risk factors may be associated with a higher risk of significant carotid bifurcation atherosclerosis. Furthermore, physicians have widely varying thresholds for requesting duplex scanning, and patient characteristics are likely to be highly variable from one vascular laboratory to another. The authors examined the relationship between significant carotid disease and atherosclerotic risk factors in patients referred to a community hospital vascular laboratory. Complete information was available for selected atherosclerotic risk factors including gender, diabetes, hypertension, cigarette smoking, cardiac disease, and prior stroke for 68 men and 78 women undergoing initial carotid duplex scanning between 4/1/93 and 11/11/93. The authors examined the possible correlation of these risk factors with the presence of severe carotid disease (greater than or equal to 50% stenosis including internal carotid occlusion) in at least one distal common carotid artery, bulb, or proximal internal carotid. Severe disease was present in 34 (23%) of 146 patients. Patients with severe carotid disease tended to be older (76.2 +/- 1.3 vs 73.4 +/- 0.9 years, mean +/- SEM), but this difference was not significant (P = 0.11). Patients with severe carotid disease tended to have more total risk factors (3.2 vs 2.1, P < 0.01). Hypertension was the best predictor of severe carotid disease (36% with, 10% without hypertension, P < 0.01). Trends toward greater likelihood of severe carotid disease in men, smokers, and in patients with cardiac disease were not significant. Risk factors may be valuable predictors of the presence or absence of significant carotid bifurcation disease. Hypertension and the total number of atherosclerotic risk factors were strong predictors of significant carotid disease in the laboratory. However, patient characteristics in individual vascular laboratories may be highly skewed and vastly different from other vascular laboratories and the population. Individual vascular laboratories should tabulate atherosclerotic risk factors in addition to indications for carotid duplex scanning so that the importance of these risk factors in each laboratory may be determined.