Many individuals suffer myocardial infarction (MI) in spite of optimal to borderline cholesterol levels. Newer tests have been proposed as adjuncts to the NCEP III guidelines to improve risk stratification for primary prevention. However, many of these tests, including advanced lipoprotein testing and carotid ultrasound (CU) have not been tested in the same population, and thus their incremental value to the guidelines remains unknown.
212 young adults (women ≤ age 65; men ≤ 55) scheduled for elective coronary angiogram had CU and labs for LDL particle concentration, size, and VLDL subtypes. Per NCEP III, 93% were stratified as low-risk for a 10-year event. Abnormal angiography was defined as stenosis severity of ≥ 50%. Group 1 (n=61) had abnormal angiograms. Group 2 (n=151) had negative angiograms.
Sensitivity for CU was 75%, specificity was 52%, and negative predictive value was 82%. Mean LDL (124 mg/dL) and total cholesterol (197 mg/dL) were optimal. Group 1 had significantly higher levels for triglyceride (172 vs. 140 mg/dL), large VLDL (70 vs. 48 mg/dL), and LDL particle concentration (LPRT) (1511 vs. 1330 nmol/L). Group 1 had significantly lower values for HDL (48 vs. 53 mg/dL), large HDL (17 vs. 21 mg/dL), and LDL particle size (20.5 vs. 20.8 nm). The OR for high LPRT compared to low was 2.9; CI: 1.3 – 6.9 (p = 0.01). Stepwise regression showed that LPRT (OR 3.1; CI: 1.2 – 7.9; p = 0.02) and CU (OR 3.9; CI: 1.7 – 8.9; p =0.001) were independently predictive of severe CAD.CONCLUSIONS: The guidelines only identified 7% at moderate or high risk. Advanced lipoprotein testing by NMR and CU independently predict angiographic CAD. Abnormal CU identifies individuals with angiographic CAD and a negative finding on CU virtually excludes CAD.
K.O. Akosah, KOS Pharmaceuticals, grant monies.