Abstract 1190: Low HDL Cholesterol Concentrations are associated with Increased Risk of Coronary Artery Calcification and CAD - Results from the Heinz Nixdorf Recall (HNR) Study
Objective: We wanted to know in as much low HDL cholesterol levels (<35 mg/dl) contribute to coronary artery calcification (CAC) and CAD in a prospective population-based cohort study (HNR study) performed to clarify the predictive value of CAC for future cardiac events by means of electron beam computed tomography (EBCT).
Methods: The study population of 4814 persons was a random sample obtained from mandatory citizen registries in 3 German cities (Ruhr area), recruited from 12/00 to 8/03. Missing HDL-C values in 24 subjects resulted to an effective sample size of 4790 (45–74 y., 50% females). Study participants underwent standardized personal interviews. We used standard enzymatic methods to quantify cholesterol, HDL-Cl, and triglycerides. C-reactive protein (hsCRP) was measured by immunonephelometry, and fibrinogen functionally. EBCT scans were done with a C-150 scanner (GE Imatron, San Francisco) using Agatston score for quantification. Qualitative variables were analyzed with Chi-Square tests, quantitative valuables using Mann-Whitney-U-tests.
Results: HDL-C < 35 mg/dl (n=284) represents the lower fifth percentile of the distribution of the cohort with a clear dominance of males (87%, n=246) over females (p<.0001). Participants with low HDL-C had significantly higher CAC scores (median:105) than those with normal HDL-C levels (median:16) (p<.0001). In the former group, the upper quartile comprises CAC scores >441 indicating a high risk for future cardiac events. Median CAC score in males with low HDL-C was 126, in women only 16 (p<.01). Low HDL-C levels were associated with elevated triglycerides (p<.0001), fibrinogen (p<.0001), hsCRP (p<.0001), lipid lowering medication (p<.0008) and diabetes (p<.0001). Of the total cohort, 325 participants (6.78%) had CAD. Among the CAD patients, 15% had low HDL-C levels and 6% normal HDL-C levels:15 vs. 6% (p<.0001).
Conclusion: HDL-C levels < 35 mg/dl, found in 5.9 % of participants of the HNR study, are correlated significantly with coronary artery calcification and CAD, early indicating subclinical atherosclerosis, especially in males. Low HDL-C levels seem to reflect a profound imbalance of lipid and carbohydrate metabolism with subsequent inflammatory and clotting activation.