Apolipoprotein B, Residual Cardiovascular Risk After Acute Coronary Syndrome, and Effects of Alirocumab

BACKGROUND: Apolipoprotein B (apoB) provides an integrated measure of atherogenic risk. Whether apoB levels and apoB lowering hold incremental predictive information on residual risk after acute coronary syndrome beyond that provided by low-density lipoprotein cholesterol is uncertain. METHODS: The ODYSSEY OUTCOMES trial (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) compared the proprotein convertase subtilisin/kexin type 9 inhibitor alirocumab with placebo in 18 924 patients with recent acute coronary syndrome and elevated atherogenic lipoproteins despite optimized statin therapy. Primary outcome was major adverse cardiovascular events (MACE; coronary heart disease death, nonfatal myocardial infarction, fatal/nonfatal ischemic stroke, hospitalization for unstable angina). Associations between baseline apoB or apoB at 4 months and MACE were assessed in adjusted Cox proportional hazards and propensity score-matched models. RESULTS: Median follow-up was 2.8 years. In proportional hazards analysis in the placebo group, MACE incidence increased across increasing baseline apoB strata (3.2 [95% CI, 2.9-3.6], 4.0 [95% CI, 3.6-4.5], and 5.5 [95% CI, 5.0-6.1] events per 100 patient-years in strata <75, 75-<90, >= 90 mg/dL, respectively; P-trend<0.0001) and after adjustment for low-density lipoprotein cholesterol (P-trend=0.035). Higher baseline apoB stratum was associated with greater relative (P-trend<0.0001) and absolute reduction in MACE with alirocumab versus placebo. In the alirocumab group, the incidence of MACE after month 4 decreased monotonically across decreasing achieved apoB strata (4.26 [95% CI, 3.78-4.79], 3.09 [95% CI, 2.69-3.54], and 2.41 [95% CI, 2.11-2.76] events per 100 patient-years in strata >= 50, >35-<50, and <= 35 mg/dL, respectively). Compared with propensity score-matched patients from the placebo group, treatment hazard ratios for alirocumab also decreased monoto