Biomarkers and Clinical Cardiovascular Outcomes With Ezetimibe in the IMPROVE-IT Trial

Abstract

Background: Addition of ezetimibe to statin therapy reduces the risk of recurrent cardiovascular (CV) events in patients with prior acute coronary syndrome (ACS). The role of biomarkers in identifying subsets of patients who may derive greater clinical benefit with ezetimibe is unknown.

Objectives: This study sought to evaluate the role of established CV biomarkers in assessing likely benefit with ezetimibe added to statin therapy in post-ACS patients.

Methods: In a pre-specified nested analysis within a randomized, double-blind trial of ezetimibe/simvastatin versus placebo/simvastatin (IMPROVE-IT [Improved Reduction of Outcomes: Vytorin Efficacy International Trial]), high-sensitivity troponin T, N-terminal pro-B-type natriuretic peptide, growth-differentiation factor-15, and high-sensitivity C-reactive protein was measured in 7,195 patients stabilized (1 month post-randomization) after ACS. A multimarker approach based on biomarker values was used to examine the risk of recurrent CV events and clinical benefit with ezetimibe.

Results: Elevated levels of each biomarker were independently associated with higher risks of CV death/myocardial infarction/stroke and CV death/heart failure (p_trend < 0.001 for each). There was a pattern of greater absolute risk reduction in CV death/myocardial infarction/stroke with the addition of ezetimibe to statin therapy in patients at higher risk on the basis of biomarker levels. High-risk patients (≥3 biomarkers "positive"; n = 1,437) had an absolute risk difference of -7.3% (95% confidence interval: -13.8% to -0.8%; p = 0.02) with ezetimibe, and intermediate-risk patients (1 to 2 biomarkers positive; n = 3,842) had an absolute risk difference of -4.4% (95% confidence interval: -9.7% to 0.8%), translating into numbers needed to treat at 7 years of 14 and 23, respectively. Low-risk patients (0 biomarkers positive; n = 1,916) did not appear to benefit from the addition of ezetimibe to statin therapy.

Conclusions: A biomarker-based strategy identifies a gradient of risk among patients post-ACS, offering the potential to identify higher-risk patients with a correspondingly high absolute benefit from the addition of ezetimibe to statin therapy.

Keywords: SIHD; biomarkers; personalized medicine; secondary prevention.