BACKGROUND: LDL cholesterol is a well established risk factor for atherosclerotic cardiovascular disease. How much one should or safely can lower this risk factor remains debated. We aimed to explore the relationship between progressively lower LDL-cholesterol concentrations achieved at 4 weeks and clinical efficacy and safety in the FOURIER trial of evolocumab, a monoclonal antibody to proprotein convertase subtilisin-kexin type 9 (PCSK9). METHODS: In this prespecified secondary analysis of 25 982 patients from the randomised FOURIER trial, the relationship between achieved LDL-cholesterol concentration at 4 weeks and subsequent cardiovascular outcomes (primary endpoint was the composite of cardiovascular death, myocardial infarction, stroke, coronary revascularisation, or unstable angina; key secondary endpoint was the composite of cardiovascular death, myocardial infarction, or stroke) and ten prespecified safety events of interest was examined over a median of 2·2 years of follow-up. We used multivariable modelling to adjust for baseline factors associated with achieved LDL cholesterol. This trial is registered with ClinicalTrials.gov, number NCT01764633. FINDINGS: Between Feb 8, 2013, and June 5, 2015, 27 564 patients were randomly assigned a treatment in the FOURIER study. 1025 (4%) patients did not have an LDL cholesterol measured at 4 weeks and 557 (2%) had already had a primary endpoint event or one of the ten prespecified safety events before the week-4 visit. From the remaining 25 982 patients (94% of those randomly assigned) 13 013 were assigned evolocumab and 12 969 were assigned placebo. 2669 (10%) of 25 982 patients achieved LDL-cholesterol concentrations of less than 0·5 mmol/L, 8003 (31%) patients achieved concentrations between 0·5 and less than 1·3 mmol/L, 3444 (13%) patients achieved concentrations between 1·3 and less than 1·8 mmol/L, 7471 (29%) patients achieved concentrations between 1·8 to less than 2·6 mmol/L, and 4395 (17%) patients achieved concentrations of 2·6 mmol/L or higher. There was a highly significant monotonic relationship between low LDL-cholesterol concentrations and lower risk of the primary and secondary efficacy composite endpoints extending to the bottom first percentile (LDL-cholesterol concentrations of less than 0·2 mmol/L; p=0·0012 for the primary endpoint, p=0·0001 for the secondary endpoint). Conversely, no significant association was observed between achieved LDL cholesterol and safety outcomes, either for all serious adverse events or any of the other nine prespecified safety events. INTERPRETATION: There was a monotonic relationship between achieved LDL cholesterol and major cardiovascular outcomes down to LDL-cholesterol concentrations of less than 0·2 mmol/L. Conversely, there were no safety concerns with very low LDL-cholesterol concentrations over a median of 2·2 years. These data support further LDL-cholesterol lowering in patients with cardiovascular disease to well below current recommendations. FUNDING: Amgen.

1st Department of Medicine University of Pécs Pécs Hungary

Amgen Thousand Oaks CA USA

Center of Preventive Cardiology 3rd Department Internal Medicine University General Hospital and 1st Medical Faculty Prague Czech Republic

Department of Internal Medicine Hypertension and Vascular Diseases The Medical University of Warsaw Warsaw Poland

Department of Molecular Medicine University of Pavia and Cardiac Intensive Care Unit and Laboratories for Experimental Cardiology IRCCS Fondazione Policlinico San Matteo Pavia Italy

Hopital Cantonal Hopitaux Universitaires de Geneva Geneva Switzerland

International Centre for Circulatory Health National Heart and Lung Institute Imperial College London London UK

Lipids and Atherosclerosis Unit Maimonides Biomedical Research Institute of Cordoba Reina Sofia University Hospital University of Cordoba CIBEROBN Cordoba Spain

Oslo University Hospital Ullevål and Medical Faculty University of Oslo Oslo Norway

Polyclinic for Endocrinology Diabetes and Preventive Medicine University of Cologne Cologne Germany

Rhode Island Hospital Department of Neurology Alpert Medical School of Brown University Providence RI USA

Sydney Medical School National Health and Medical Research Council Clinical Trials Centre University of Sydney Sydney NSW Australia

TIMI Study Group Division of Cardiovascular Medicine Brigham and Women's Hospital Boston MA USA

University Hospital Center Besançon Besançon France

Nat Rev Cardiol. 2017 Nov;14(11):630-631. doi: 10.1038/nrcardio.2017.149. PubMed

Lancet. 2018 Mar 10;391(10124):933-934. doi: 10.1016/S0140-6736(18)30530-0. PubMed

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ClinicalTrials.gov
NCT01764633