Background: Elevated lipoprotein(a) (Lp[a]) concentrations are associated with increased cardiovascular event risk even in the presence of well-controlled low-density lipoprotein cholesterol levels, but few treatments are documented to reduce this residual risk., Objectives: The aim of this post hoc analysis of REDUCE-IT (Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial) was to explore the cardiovascular benefit of icosapent ethyl (IPE) across a range of Lp(a) levels., Methods: A total of 8,179 participants receiving statin therapy with established cardiovascular disease or age ≥50 years with diabetes and ≥1 additional risk factor, fasting triglyceride 1.69 to 5.63 mmol/L, and low-density lipoprotein cholesterol 1.06 to 2.59 mmol/L were randomized to receive 2 g twice daily of IPE or matching placebo. Relationships between continuous baseline Lp(a) mass concentration and risk for first and total (first and subsequent) major adverse cardiovascular events (MACE) were analyzed, along with the effects of IPE on first MACE among those with Lp(a) concentrations ≥50 or <50 mg/dL., Results: Among 7,026 participants (86% of those randomized) with baseline Lp(a) assessments, the median concentration was 11.6 mg/dL (Q1-Q3: 5.0-37.4 mg/dL). Lp(a) had significant relationships with first and total MACE (P < 0.0001), while event reductions with IPE did not vary across the range of Lp(a) (interaction P > 0.10). IPE significantly reduced first MACE in subgroups with concentrations ≥50 and <50 mg/dL., Conclusions: Baseline Lp(a) concentration was prognostic for MACE among participants with elevated triglyceride levels receiving statin therapy. Importantly, IPE consistently reduced MACE across a range of Lp(a) levels, including among those with clinically relevant elevations., Competing Interests: Funding Support and Author Disclosures This work was supported by Amarin. Dr Szarek serves as a consultant for and/or has received research support from CiVi, Resverlogix, Lexicon, Baxter, Esperion, Amarin, NewAmsterdam, Silence, Sanofi, and Regeneron Pharmaceuticals. Dr Bhatt served as chair of REDUCE-IT, with research funding paid to Brigham and Women’s Hospital and the Icahn School of Medicine at Mount Sinai; is an advisory board member for Angiowave, Bayer, Boehringer Ingelheim, CellProthera, Cereno Scientific, Elsevier Practice Update Cardiology, High Enroll, Janssen, Level Ex, McKinsey, Medscape Cardiology, Merck, MyoKardia, NirvaMed, Novo Nordisk, PhaseBio, PLx Pharma, and Stasys; is a member of the boards of directors for the American Heart Association, Angiowave (with stock options), Bristol Myers Squibb (with stock), DRS.LINQ (with stock options), and High Enroll (with stock); is a consultant for Broadview Ventures, GlaxoSmithKline, Hims, SFJ Pharmaceuticals, and Youngene Therapeutics; is a member of data and safety monitoring committees for Acesion Pharma, Assistance Publique–Hôpitaux de Paris, the Baim Institute for Clinical Research (formerly the Harvard Clinical Research Institute, for the PORTICO trial, funded by St. Jude Medical, now Abbott), Boston Scientific (chair, PEITHO trial), the Cleveland Clinic, Contego Medical (chair, PERFORMANCE 2), the Duke Clinical Research Institute, the Mayo Clinic, Mount Sinai School of Medicine (for the ENVISAGE trial, funded by Daiichi-Sankyo; for the ABILITY-DM trial, funded by Concept Medical; and for ALLAY-HF, funded by Alleviant Medical), Novartis, the Population Health Research Institute, and Rutgers University (for the National Institutes of Health–funded MINT trial); has received honoraria from the American College of Cardiology (senior associate editor, Clinical Trials and News, ACC.org; chair, American College of Cardiology Accreditation Oversight Committee), the Arnold and Porter law firm (work related to Sanofi/Bristol Myers Squibb clopidogrel litigation), the Baim Institute for Clinical Research (formerly the Harvard Clinical Research Institute, RE-DUAL PCI clinical trial steering committee funded by Boehringer Ingelheim, and AEGIS-II executive committee funded by CSL Behring), Belvoir Publications (editor-in-chief, Harvard Heart Letter), the Canadian Medical and Surgical Knowledge Translation Research Group (clinical trial steering committees), CSL Behring (American Heart Association lecture), Cowen & Company, the Duke Clinical Research Institute (clinical trial steering committees, including for the PRONOUNCE trial, funded by Ferring Pharmaceuticals), HMP Global (editor-in-chief, Journal of Invasive Cardiology), the Journal of the American College of Cardiology (guest editor, associate editor), K2P (cochair, interdisciplinary curriculum), Level Ex, Medtelligence/ReachMD (continuing medical education steering committees), MJH Life Sciences, Oakstone CME (course director, Comprehensive Review of Interventional Cardiology), Piper Sandler, the Population Health Research Institute (for the COMPASS operations committee, publications committee, steering committee, and U.S. national coleader, funded by Bayer), WebMD (continuing medical education steering committees), and John Wiley (steering committee); is deputy editor of Clinical Cardiology; is named on a patent for sotagliflozin assigned to Brigham and Women’s Hospital, which assigned to Lexicon (neither Dr Bhatt nor Brigham and Women’s Hospital receives any income from this patent); has received research funding from 89Bio, Abbott, Acesion Pharma, Afimmune, Aker Biomarine, Alnylam, Amarin, Amgen, AstraZeneca, Bayer, Beren, Boehringer Ingelheim, Boston Scientific, Bristol Myers Squibb, Cardax, CellProthera, Cereno Scientific, Chiesi, CinCor, Cleerly, CSL Behring, Eisai, Ethicon, Faraday Pharmaceuticals, Ferring Pharmaceuticals, Forest Laboratories, Fractyl, Garmin, HLS Therapeutics, Idorsia, Ironwood, Ischemix, Janssen, Javelin, Lexicon, Lilly, Medtronic, Merck, Moderna, MyoKardia, NirvaMed, Novartis, Novo Nordisk, Otsuka, Owkin, Pfizer, PhaseBio, PLx Pharma, Recardio, Regeneron, the Reid Hoffman Foundation, Roche, Sanofi, Stasys, Synaptic, The Medicines Company, and Youngene; has received royalties from Elsevier (editor, Braunwald’s Heart Disease); is a site coinvestigator for Abbott, Biotronik, Boston Scientific, CSI, Endotronix, St. Jude Medical (now Abbott), Philips, SpectraWAVE, Svelte, and Vascular Solutions; is a trustee of the American College of Cardiology; and has conducted unfunded research for FlowCo. Dr Miller has received consulting fees from 89Bio, Amarin, and Pfizer. Dr Brinton has received speaker fees from Amarin, Amgen, Amryt, and Esperion; and has received consulting fees from 89Bio, Amarin, Amgen, Amryt, DelCor, Esperion, Immunovant, Ionis, Merck, NovoNordisk, and Pfizer. Dr Jacobson has received consulting fees from Amgen, Esperion, Novartis, Regeneron, and Sanofi. Dr Tardif has received grants from Amarin, AstraZeneca, Ceapro, DalCor Pharmaceuticals, Esperion, Ionis, Novartis, Pfizer, and RegenXBio; has received honoraria from AstraZeneca, DalCor Pharmaceuticals, HLS Pharmaceuticals, Pendopharm, and Pfizer; holds minor equity interest in DalCor Pharmaceuticals; and holds patents on pharmacogenomics-guided cholesteryl ester transfer protein inhibition and the use of colchicine-12 after myocardial infarction. Dr Ballantyne has received grant and research support (all significant and paid to the institution) from Abbott Diagnostic, Akcea, Amgen, Arrowhead, Esperion, Ionis, Merck, Novartis, Novo Nordisk, Regeneron, Roche Diagnostic, the National Institutes of Health, the American Heart Association, and the American Diabetes Association; is a consultant (modest except as noted) for 89Bio, Abbott Diagnostics, Alnylam Pharmaceuticals, Althera, Amarin, Amgen, Arrowhead, AstraZeneca, Denka Seiken (significant), Esperion, Genentech, Gilead, Illumina, Ionis, Matinas BioPharma, Merck, New Amsterdam (significant), Novartis, Novo Nordisk, Pfizer, Regeneron, and Roche Diagnostic. Dr Mason has received research funding or consulting fees from Amarin, Lexicon, Esperion, and HLS Therapeutics. Dr Ph. Gabriel Steg has received grants, personal fees, and nonfinancial support from Sanofi; has received grants and personal fees from Amarin, Servier, and Bayer; and has received personal fees from Amgen, AstraZeneca, Bristol Myers Squibb, Boehringer Ingelheim, Idorsia, Pfizer, and Novartis. Dr Ketchum, Dr Lira Pineda, and Mr Doyle are employees and stockholders of Amarin Pharma., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)