15289-s-bos

90 | Chapter 6 Blood analyses Fasting blood was collected, processed the same day and EDTA plasma samples were stored at -80 o C. Within 30 months Lp(a) levels were determined in once thawed samples using an apo(a)-size independent immunoturbidimetric assay (Lp(a) 21 FS, DiaSys, Holzheim, Germany). Other lipid levels were measured according to the standard laboratory techniques. Carotid ultrasonography All carotid ultrasound measurements were performed on the Panasonic CardioHealthStation (Yokohama, Japan), with a validated automated C-IMT capturing method [20] (figure 1). Subjects were examined in supine position with their head positioned in an angle of approximately 45 degrees. A plaque scan was performed by placing the transducer transversally, visualizing the common, internal, and external carotid artery. Plaques were defined as a local enlargement of the C-IMT of more than 50% of the surrounding C-IMT, or if the C-IMT was above 1.5 mm, and were scored as present or absent. The mean C-IMT was measured over 1 cm length, at least 0.5 cm proximal of the bifurcation in the common carotid artery. Both sides were measured in two angles: anterior (170°-190°), and lateral (right: 120°-145°; left: 210°-235°), as indicated in real time by the device (Figure 1). In the present study, the C-IMT indicates the mean of the left and right mean C-IMT. Statistical analysis: Data with a normal distribution were expressed as mean (±SD), and data with a skewed distribution as median (IQR). Groups were compared a Chi-Square test or ANOVA. Skewed data was logistically transformed. High baseline Lp(a) was defined as > 0.3 g/L and low as ≤ 0.3 g/L. This level has been reported to be the approximate median Lp(a) level in the general population [21, 22]. The associations between Lp(a) and the presence of carotid plaques and C-IMT were examined by logistic and linear regression methods, respectively. Additionally, these analyses were repeated in a subgroup of those with an LCL-C above 4mmol/L. Finally, associations between other variables and the presence of carotid plaques and C-IMT were assessed.