Persistent arterial wall inflammation in patients with elevated lipoprotein(a) despite strong low-density lipoprotein cholesterol reduction by proprotein convertase subtilisin/kexin type 9 antibody treatment

Abstract

Aims: Subjects with lipoprotein(a) [Lp(a)] elevation have increased arterial wall inflammation and cardiovascular risk. In patients at increased cardiovascular risk, arterial wall inflammation is reduced following lipid-lowering therapy by statin treatment or lipoprotein apheresis. However, it is unknown whether lipid-lowering treatment in elevated Lp(a) subjects alters arterial wall inflammation. We evaluated whether evolocumab, which lowers both low-density lipoprotein cholesterol (LDL-C) and Lp(a), attenuates arterial wall inflammation in patients with elevated Lp(a).

Methods and results: In this multicentre, randomized, double-blind, placebo-controlled study, 129 patients {median [interquartile range (IQR)]: age 60.0 [54.0-67.0] years, Lp(a) 200.0 [155.5-301.5] nmol/L [80.0 (62.5-121.0) mg/dL]; mean [standard deviation (SD)] LDL-C 3.7 [1.0] mmol/L [144.0 (39.7) mg/dL]; National Cholesterol Education Program high risk, 25.6%} were randomized to monthly subcutaneous evolocumab 420 mg or placebo. Compared with placebo, evolocumab reduced LDL-C by 60.7% [95% confidence interval (CI) 65.8-55.5] and Lp(a) by 13.9% (95% CI 19.3-8.5). Among evolocumab-treated patients, the Week 16 mean (SD) LDL-C level was 1.6 (0.7) mmol/L [60.1 (28.1) mg/dL], and the median (IQR) Lp(a) level was 188.0 (140.0-268.0) nmol/L [75.2 (56.0-107.2) mg/dL]. Arterial wall inflammation [most diseased segment target-to-background ratio (MDS TBR)] in the index vessel (left carotid, right carotid, or thoracic aorta) was assessed by 18F-fluoro-deoxyglucose positron-emission tomography/computed tomography. Week 16 index vessel MDS TBR was not significantly altered with evolocumab (-8.3%) vs. placebo (-5.3%) [treatment difference -3.0% (95% CI -7.4% to 1.4%); P = 0.18].

Conclusion: Evolocumab treatment in patients with median baseline Lp(a) 200.0 nmol/L led to a large reduction in LDL-C and a small reduction in Lp(a), resulting in persistent elevated Lp(a) levels. The latter may have contributed to the unaltered arterial wall inflammation.

Keywords: Arterial wall inflammation; Atherosclerosis; Evolocumab; Lipoprotein(a); PCSK9 antibodies.

Figure 1

Mean change from baseline in (A) low-density lipoprotein cholesterol and (B) lipoprotein(a) over time. Vertical bar indicates 95% confidence interval. QM, monthly.

Figure 2

Least squares mean percentage change from baseline in most diseased segment target-to-background ratio of index vessel P = 0.18 for evolocumab vs. placebo). Vertical bar indicates 95% confidence interval.

Take home figure

The combination of lowering low-density lipoprotein cholesterol by 61% compared with placebo to a mean of 1.6 mmol/L (60 mg/dL), and lipoprotein(a) by 14% compared with placebo to a median of 188 nmol/L (75 mg/dL) with PCSK9 inhibition does not reduce inflammatory activity in the arterial wall of patients with lipoprotein(a) elevation, highlighting an unmet need for potent lipoprotein(a)-lowering interventions in order to adequately test the benefit of such an intervention.