Malondialdehyde-modified LBL as a marker of acute coronary syndromes

Context Release of circulating malondialdehyde (MDA)-modified low-density l ipoprotein (LDL) may reflect endothelial injury or plaque instability. Objective To determine the usefulness of MDA-modified LDL for identifying p atients with unstable angina and acute myocardial infarction (AMI). Design Blinded comparison of MDA-modified LDL, C-reactive protein, and trop onin I followed by multiple receiver operating curve analysis. Setting University hospital. Participants A total of 104 consecutive patients with acute coronary syndro mes (42 with unstable angina and 62 with AMI), and 64 patients with stable coronary artery disease (CAD) without evidence of ischemia. Main Outcome Measures Ability of MDA-modified LDL, C-reactive protein, and troponin I to discriminate patients with stable CAD, unstable angina, or AM I, Results Malondialdehyde-modified LDL (chi(2) = 10.2; P = .001), but not tro ponin I or C-reactive protein, discriminated between stable CAD and unstabl e angina. Troponin I (chi(2) = 14.5; P<.001), but not MDA-modified LDL or C -reactive protein, discriminated between unstable angina and AMI. Both MDA- modified LDL and troponin I (chi(2) = 14.5; P<.001 and chi(2) = 5.3; P = .0 2, respectively) but not C-reactive protein discriminated between stable CA D and AMI. The sensitivity of MDA-modified LDL was 95% for unstable angina and 95% for AMI, with a specificity of 95%. Values for troponin I were 38% and 90%, respectively, with a specificity of 95%. The combination of MDA-mo dified LDL and troponin I had a sensitivity of 98% for unstable angina and 100% for AMI, with a specificity of 99%. Conclusion The combination of MDA-modified LDL, which may reflect endotheli al injury or plaque instability, and troponin I, which reflects myocardial cell injury, allows better discrimination between stable CAD and acute coro nary syndromes than troponin I alone.