Alirocumab and Cardiovascular Outcomes after Acute Coronary Syndrome (ODYSSEY Outcomes)

The ODYSSEY Outcomes trial randomized 18,924 patients who had experienced an acute coronary syndrome (ACS) 1–12 months prior and were on high-intensity statin therapy to alirocumab or placebo, with median follow-up of 2.8 years.

Alirocumab was titrated to achieve LDL-C of 25–50 mg/dL, or reduced if LDL-C fell below 15 mg/dL. The primary endpoint — cardiovascular death, MI, ischemic stroke, or hospitalization for unstable angina — was reduced by 15% (HR 0.85, p<0.001). All-cause mortality was nominally reduced (HR 0.85, 3.5% vs. 4.1%, p=0.026). Individual components showed significant reductions in MI and ischemic stroke; unstable angina hospitalization was reduced 39%.

Critically, the subgroup with baseline LDL-C ≥100 mg/dL derived the greatest absolute benefit — consistent with LDL-C-driven risk, where those furthest from target have the most to gain from additional lowering. In the overall trial, the absolute risk reduction was 1.6 percentage points over 2.8 years.

ODYSSEY Outcomes is the twin to FOURIER in establishing the PCSK9 inhibitor class in secondary prevention. Its post-ACS design tests the agents in the highest-risk window — immediately after a qualifying event — and demonstrates significant mortality reduction where FOURIER (with a median 2.2-year follow-up) did not. The nominally significant all-cause mortality result, while modest in absolute terms, is clinically meaningful in a trial of this size.

We rate the evidence strong. A landmark PCSK9 inhibitor outcomes trial demonstrating significant cardiovascular event reduction after ACS, with nominally significant all-cause mortality benefit — establishing alirocumab’s role in the highest-risk secondary prevention setting.