Plasma sphingomyelin and subclinical atherosclerosis: findings from the multi-ethnic study of atherosclerosis.

Plasma sphingomyelin has been shown to be an independent risk factor for coronary heart disease, but the relation of plasma sphingomyelin to earlier, subclinical atherosclerotic disease has not been reported. The authors examined the association between plasma sphingomyelin and three measures of subclinical cardiovascular disease (carotid intimal-medial wall thickness, ankle-arm blood pressure index, and Agatston coronary artery calcium score) among 6,814 middle-aged, asymptomatic adults in the Multi-Ethnic Study of Atherosclerosis, which was initiated in 2000. The sphingomyelin level was positively correlated with lipids and the Framingham risk score (p < 0.01 for both), and the mean level was higher in women than men (50 (standard deviation (SD), 16) vs. 45 (SD, 15) mg/dl) (p < 0.01) and higher in never versus current smokers (49 (SD, 16) vs. 45 (SD, 17) mg/dl) (p < 0.01). Women with sphingomyelin levels of 60 or more mg/dl had more severe subclinical disease by all three measures than did the referent group with sphingomyelin levels of 39 or less mg/dl, although associations were not significant after multivariate adjustment for standard cardiovascular disease risk factors. Men with sphingomyelin levels of 60 or more mg/dl versus those with sphingomyelin levels of 39 or less mg/dl had higher calcium scores (135 vs. 99 Agatston units) (p = 0.01). These observations are consistent with the hypothesis that plasma sphingomyelin is in the biologic pathway that mediates the risk for subclinical disease attributable to standard cardiovascular disease risk factors.