HDL Particle Number in Patients with Angiographic Coronary Artery Disease on Lipid-Lowering Medication

Background: Measures of LDL particle concentration (LDL-P) have been shown to better predict the risk of future cardiovascular events than LDL cholesterol (LDL-C). Many patients with coronary artery disease are treated with lipid-lowering drugs to reduce LDL-C to treatment goals below 80 mg/dL. However despite successful LDL-C lowering, many patients continue to experience cardiovascular events (i.e. residual cardiovascular risk). Drugs that effectively reduce LDL-C to target goals (e.g., statins) often do not reduce LDL-P to the same extent. Thus, more aggressive treatment regimes may be required to achieve LDL-P goals. Objective: To assess variations in lipoprotein particle concentrations in patients with coronary artery disease diagnosed by angiography who are receiving lipid-lowering therapy, in order to determine residual cardiovascular risk. Methods: Data were derived from a single laboratory database (Cardiology of Atlanta, PC). Cases were patients diagnosed with coronary artery disease by angiography who were on lipid-lowering therapy and whose serum was analyzed for lipoprotein concentrations using NMR between June 2010 and March 2012. Total cholesterol, triglycerides and HDL cholesterol were measured using standard automated methods and LDL-C was calculated using the Friedewald equation. The NMR lipoprotein profile was determined using a 400-MHz proton NMR analyzer. Results: Among the 83 patients meeting inclusion criteria, 78% were men and the mean age was 64 years old. Mean LDL-C was 85 + 30 mg/dL, mean HDL-C was 47 + 14 mg/dL and mean LDL-P was 1364 + 510 nmol/L. Most patients had LDL-C levels within the target goal for high risk patients: 64% had LDL-C levels th MESA percentile) while 52% had LDL-C levels th MESA percentile). However, LDL-P levels for most patients were higher than goals: Only 18% had LDL-P levels th MESA percentile) and 6% had LDL-P levels th MESA percentile). Conclusion: The majority of patients in this high risk cohort with angiographic coronary artery disease on lipid-lowering therapy met LDL-C target goals, but failed to achieve LDL-P goals suggesting that they harbor residual risk for cardiovascular events.