Benefit of Combination Ezetimibe/Simvastatin Among High-Risk Populations: Lessons from the IMPROVE-IT Trial

The Improved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT) demonstrated the clinical benefit of the combination of ezetimibe-simvastatin compared to placebo-simvastatin following acute coronary syndrome (ACS). This review highlights key findings from this study with particular attention to the practice-changing impact on guidelines for low-density lipoprotein cholesterol (LDL-C) reduction after ACS, especially among high-risk populations.

Consistent reductions in LDL-C have been reported with newer lipid-lowering therapies (proprotein convertase subtilisin/kexin type 9 inhibitors, cholesterol ester transfer proteins, bempedoic acid) in combination with statin in high-risk subgroups. Since high-risk subgroups remain a focus of guidelines, exploration of high-risk subgroups can help define the optimal use of new therapies. Ezetimibe reduced the LDL-C by 16.7 mg/dL compared to placebo at 1 year, resulting in a significant reduction in the primary composite endpoint (absolute risk difference 2.0%; relative risk difference 6.4%, hazard ratio, 0.936; 95% confidence interval, 0.89 to 0.99; P = 0.016). The benefits achieved with ezetimibe in both LDL-C reduction and the primary clinical composite across 10 pre-specified high-risk subgroups, including the elderly; women; patients with diabetes, prior coronary artery bypass graft, history of stroke, polyvascular disease, low baseline LDL-C, renal dysfunction, prior heart failure, and an elevated TIMI risk score for secondary prevention, were similar or greater than in the corresponding non-high-risk subgroups. Safety events were similar between ezetimibe and placebo across the high-risk subgroups. These data support the addition of ezetimibe to statin therapy in high-risk patients who require additional therapy to lower the LDL-C post-ACS.