High pre-β1 HDL concentrations and low lecithin: Cholesterol acyltransferase activities are strong positive risk markers for ischemic heart disease and independent of HDL-cholesterol

Abstract

BACKGROUND: We hypothesized that patients with high HDL-cholesterol (HDL-C) and ischemic heart disease (IHD) may have dysfunctional HDL or unrecognized nonconventional risk factors. METHODS: Individuals with IHD (Copenhagen University Hospital) and either high HDL-C (n = 53; women ≥735 mg/L; men ≥619 mg/L) or low HDL-C (n = 42; women ≤387 mg/L; men ≤341 mg/L) were compared with individuals without IHD (Copenhagen City Heart Study) matched by age, sex, and HDL-C concentrations (n = 110). All participants had concentrations within reference intervals for LDL-C (<1600 mg/L) and triglyceride (<1500 mg/L), and none were treated with lipid-lowering medications. Pre-β1 HDL and phospholipid transfer protein concentrations were measured by using commercial kits and lecithin:cholesterol acyltransferase (LCAT) activity by using a proteoliposome cholesterol esterification assay. RESULTS: Pre-β1 HDL concentrations were 2-fold higher in individuals with IHD vs no IHD in both the high [63 (5.7) vs 35 (2.3) mg/L; P < 0.0001] and low HDL-C [49 (5.0) vs 27 (1.5) mg/L; P = 0.001] groups. Low LCAT activity was also associated with IHD in the high [95.2 (6.7) vs 123.0 (5.3) μmol·L-1·h-1; P = 0.002] and low [93.4 (8.3) vs 113.5 (4.9) μmol·L-1·h -1; P = 0.03] HDL-C groups. ROC curves for pre-β1 HDL in the high-HDL-C groups yielded an area under the curve of 0.71 (95% CI: 0.61-0.81) for predicting IHD, which increased to 0.92 (0.87-0.97) when LCAT was included. Similar results were obtained for low HDL-C groups. An inverse correlation between LCAT activity and pre-β1 HDL was observed (r2 = 0.30; P < 0.0001) in IHD participants, which was stronger in the low HDL-C group (r2 = 0.56; P < 0.0001). CONCLUSIONS: IHD was associated with high pre-β1 HDL concentrations and low LCAT levels, yielding correct classification in more than 90% of the IHD cases for which both were measured, thus making pre-β1 HDL concentration and LCAT activity level potentially useful diagnostic markers for cardiovascular disease. © 2010 American Association for Clinical Chemistry.