High intensity statin-ezetimibe combination therapy reduces mortality in patients with ischaemic heart disease and elevated Lipoprotein(a)

Abstract

Abstract Background Early and prompt reduction of low-density lipoprotein cholesterol concentrations (LDL-C) using combination lipid-lowering therapy (LLT) is recommended to lower cardiovascular risk in patients with ischaemic heart disease (IHD) and elevated LDL-C. Lowering LDL-C is also an important cardiovascular risk mitigation strategy in patients with elevated lipoprotein(a) [Lp(a)]. However, it is unknown if combination LLT reduces mortality in patients with elevated Lp(a). Aim To undertake an observational study to investigate the effect of combination LLT using high intensity statin with ezetimibe on cardiovascular outcomes in patients with and without elevated Lp(a). Methods Serum Lp(a) concentrations were measured in 520 consecutively recruited patients with IHD admitted to hospital, half of whom were admitted for acute myocardial infarction. Patients treated with high intensity statin and ezetimibe within the 1st year from admission to hospital (‘HI statin-ezetimibe group’, n=157) were compared with the rest of patients who had less intensive lipid lowering regimen (‘Others group’, n=363) for cardiovascular outcomes. Results During the 2-year follow-up period, 14.6%, 6.5%, and 53.1% of patients had all-cause mortality, cardiovascular mortality, and major adverse cardiovascular events (MACE) respectively. Median age was 63.5 years and 82.3% were male. Multivariable Cox regression showed that baseline Lp(a) ≥70 nmol/L was associated with increased risk of all-cause mortality (HR 1.97, 95% CI 1.20-3.22, P=0.007). Compared with a less intensive regimen, HI statin-ezetimibe was associated with reduced risk of all-cause mortality (HR 0.44 [0.21-0.89], P=0.023) and MACE (HR 0.71 [0.52-0.95], P=0.027), with no statistically significant effect on cardiovascular mortality (HR 0.43, P=0.142). Notably, the cardiovascular benefits of HI statin-ezetimibe were more pronounced in patients with elevated Lp(a); a greater reduction in risk of MACE was seen for patients with Lp(a) ≥70 nmol/L (HR 0.51, P=0.007) or Lp(a) ≥100 nmol/L (HR 0.36, P=0.009), and in all-cause mortality risk for those with Lp(a) ≥70 nmol/L (HR 0.24, P=0.025). Although LDL-C reduction >50% was associated with reduced risk of all-cause mortality (p=0.027), this could not fully explain the overall cardiovascular benefit of HI statin-ezetimibe use in patients with or without elevated Lp(a). Conclusion Intensification of lipid-lowering therapy with high-intensity statin and ezetimibe improves cardiovascular outcomes in patients at very high cardiovascular risk, particularly those with elevated Lp(a). Larger studies are required to confirm our findings that this cardiovascular benefit is partially independent of LDL-C lowering.