Low density lipoprotein particle size and risk of early-onset myocardial infarction in women

Previous studies of middle-aged men have shown a univariate association bet ween low density lipoprotein (LDL) particle diameter (size) and coronary he art disease, but this association has yet to be examined in younger women. Using a subsample from a population-based case-control study of women livin g in western Washington State, the authors examined the association between LDL particle size and risk of early-onset myocardial infarction (MI) in 19 92-1995. Gradient gel electrophoresis was used to characterize LDL subclass es in nonfasting blood samples from 72 MI cases and 159 controls aged 20-44 years. Mean LDL particle size in cases was significantly smaller compared with controls (26.4 vs. 26.9 nm, p < 0.001), with an odds ratio of 2.3 (p < 0.0001) for a 1-nm smaller LDL particle size. These results were independe nt of age, menopausal status, smoking, diabetes, hypertension, and LDL chol esterol (odds ratios = 1.9-2.3 for a l-nm smaller LDL particle size, all p < 0.02) but were not independent of body mass index, high density lipoprote in cholesterol, or triglyceride (odds ratios = 1.4, 1.4, and 1.1, respectiv ely; all p > 0.05). Therefore, in age-adjusted analyses, smaller LDL partic le size was associated with MI in young women, but the risk was attenuated after adjustments for metabolic factors related to both LDL particle size a nd MI.