Background Raising the cholesterol of HDL contaminants is targeted being a coronary disease prevention technique. healthy women initially. Throughout a median follow-up of 17 years 969 situations of occurrence CHD (myocardial infarction revascularization AVL-292 and CHD loss of life) were ascertained. In Cox models that modified for age race/ethnicity blood pressure smoking postmenopausal status and hormone therapy associations with event CHD were inverse (<0.0001) to ? 0.26 (for the very small HDL subclass <0.0001). In comparison total HDL-P (the sum of the HDL subclasses) experienced the strongest correlation with the medium and large HDL subclasses (for those <0.0001. The correlation coefficients for the five HDL particle subclasses with each other ranged from 0.38 to ? 0.37 for those <0.0001. The HDL subclasses also AVL-292 differed in the direction and magnitude of correlation with LDL cholesterol and particle concentration ApoB triglycerides and BMI going from bad (=0.0003). Related results were acquired when the HDL subclasses were examined per 1-SD increments. Stratified Analyses Event rates differed in participants with AVL-292 ApoB<90 versus ≥90 mg/dL (1.4% and 4.9% respectively). The associations of HDL subclasses with event CHD were significant only among participants with ApoB ≥90mg/dL (Furniture 4 and ?and5) 5 with statistically significant relationships by ApoB for the association of total HDL-P and the large HDL subclass with event CHD (for connection =0.01 and 0.003 respectively). CHD events rates were related in baseline users and non-users of HRT (3.7%). Somewhat attenuated associations were seen among HRT users with only the large HDL subclass having statistically significant connection by HRT use (for connection =0.02 data not shown). Table 4 Association of HDL particle subclasses with event CHD AVL-292 in participants with apolipoprotein B ≥ 90mg/dL (N=17 227 CHD events =838) Table 5 Association of HDL particle subclasses with event CHD in participants with apolipoprotein B < 90 mg/dL (N=9 100 CHD events =131) DISCUSSION With this prospective study of 26 332 in the beginning healthy women adopted for any median duration of 17 years differential associations with event CHD events were found for baseline concentrations of five HDL subclasses measured by NMR spectroscopy and grouped relating to a newly proposed classification plan. Before accounting for the correlations of the HDL subclasses with each other and with AVL-292 metabolic and lipoprotein variables the very large large and medium HDL subclasses Tnf experienced inverse association with CHD while small and very small HDL subclasses experienced positive association. Once the correlations were accounted for associations for the spectrum of large medium and small HDL subclasses showed a inclination towards a AVL-292 reduced risk of CHD (p-tendency<0.05 for large and small 0.07 for medium) while the subclasses at either end of the spectrum were not associated with CHD (p-tendency =0.97 and 0.21 for very large and very small HDL respectively). These findings underscore the heterogeneity of HDL particle subclasses in conveying medical CHD risk info. This is the 1st study to examine event CHD associations in relation to NMR-measured HDL particle subclasses grouped according to the five subclasses that were recently recommended.8 Related studies that have assessed the association between HDL subclasses and CHD risk by NMR spectroscopy have previously grouped HDL particles into three subclasses (large medium and small).9 13 19 The previously designated NMR derived “large” HDL subclass corresponds to the “very large” HDL subclass assessed in the present study while the previously designated “small” HDL particle subclass is a combination of both the “very small” and “small” HDL subclasses assessed in the present study.8 Using the new classification scheme additionally identified a very small HDL subclass which was not associated with CHD in our study and refined the range of medium to large HDL subclasses. Hence this new HDL subclass distribution may provide better assessment of CHD risk attributable to specific HDL particle subclasses. In a previous case-control study of high-risk men with established CHD and low HDL-C all three subclasses tended towards a reduced risk of CHD although only small.