Background: Aficamten is a cardiac myosin inhibitor that mitigates left ventricular outflow gradients in obstructive hypertrophic cardiomyopathy (oHCM). The clinical efficacy of aficamten across multiple outcome domains in oHCM has not been fully defined., Objectives: This responder analysis from the SEQUOIA-HCM (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic oHCM) trial characterizes the clinical impact of aficamten., Methods: Patients who were symptomatic of oHCM were randomized to aficamten (n = 142) or placebo (n = 140) daily for 24 weeks. Outcomes assessed included the proportion of patients with complete hemodynamic response (rest and Valsalva gradient <30 mm Hg and <50 mm Hg, respectively), relief in limiting symptoms (≥1 improvement in NYHA functional class and/or ≥10-point change in Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score), enhanced exercise capacity (≥1.5 mL/kg/min change in peak oxygen uptake), and ≥50% reduction in N-terminal pro-B-type natriuretic peptide. Eligibility for septal reduction therapy was also evaluated., Results: At 24 weeks, patients treated with aficamten vs placebo showed significant improvement in limiting symptoms (71% vs 42%), were more likely to have complete hemodynamic response (68% vs 7%), demonstrated enhanced exercise capacity (47% vs 24%), and showed a decrease ≥50% in N-terminal pro-B-type natriuretic peptide (84% vs 8%) (P ≤ 0.002 for all). An improvement in ≥1 of these outcome measures was achieved in 97% of patients treated with aficamten (vs 59% placebo), including 23% on aficamten who achieved all 4 outcomes compared with none in placebo. Among 32 patients receiving aficamten and 29 patients receiving placebo who were eligible for septal reduction therapy, 28 (88%) from the aficamten group were no longer eligible at 24 weeks compared with 15 (52%) from the placebo group (P = 0.002)., Conclusions: Treatment with aficamten was associated with substantial improvements across a broad range of clinically relevant efficacy measures. These results underscore the wide-ranging potential of aficamten for treatment of patients with symptomatic oHCM (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults with oHCM [SEQUOIA-HCM]; NCT05186818)., Competing Interests: Funding Support and Author Disclosures The SEQUOIA-HCM study was funded by Cytokinetics, Incorporated. Dr Maron has received consultant/advisor fees from Imbria, Edgewise, and BioMarin; and has received steering committee fees for SEQUIOA-HCM from Cytokinetics. Dr Masri has received consultant/advisor fees from Tenaya, Attralus, Cytokinetics, Bristol Myers Squibb, and Ionis; and has received research grants from Ionis, Akcea, Pfizer, Ultromics, and the Wheeler Foundation. Dr Nassif has received research and grant support from AstraZeneca and Cytokinetics; and has received consulting/advisory fees from Vifor and Cytokinetics. Dr Barriales-Villa has received consultant/advisor fees from MyoKardia/Bristol Myers Squibb. Dr Arad has received consulting and lecture fees from Bristol Myers Squibb. Dr Cardim has received consultant/advisor fees from Cytokinetics, Bristol Myers Squibb, Pfizer, Menarini, Boehinger Ingelheim, and Bial. Dr Coats has received speaker fees from Alnylam and Roche; and has received advisor fees from Cytokinetics. Dr Düngen has received grants from Novartis, CSL Behring, and Cytokinetics. Dr Garcia-Pavia has received speakers’ bureau fees from Pfizer, AstraZeneca, Novo Nordisk, Ionis, Bridgebio, Bristol Myers Squibb, Intelllia, and Alnylam; has received consulting/advisor fees from Pfizer, Alnylam, MyoKardia/Bristol Myers Squibb, Cytokinetics, Neuroimmune, Intellia, Ionis, Bridgebio, Lexeo, Rocket, Attralus, and AstraZeneca; and has received research/educational grants to his institution from Pfizer, AstraZeneca, Novo Nordisk, BridgeBio, and Alnylam. Dr Hagège has received consulting/advisor fees from Alnylam, Amicus Therapeutics, Bayer, MyoKardia/Bristol Myers Squibb, Pfizer, and Sanofi Genzyme; and has received steering committee fees for SEQUOIA-HCM from Cytokinetics. Dr Januzzi is funded in part by the Hutter Family Professorship; is a Trustee of the American College of Cardiology; has served as a board member for Imbria Pharmaceuticals; has served as a Director at Jana Care; has received grant support from Abbott, Applied Therapeutics, HeartFlow, Innolife, and Roche Diagnostics; has received consulting fees from Abbott, Beckman, Bristol Myers Squibb, Boehringer Ingelheim, Janssen, Novartis, Pfizer, Merck, Roche Diagnostics, and Siemens; and has participated in clinical endpoint committees/data safety monitoring boards for Abbott, AbbVie, CVRx, Intercept, and Takeda. Dr Lee has received research grants through his institution from AstraZeneca, Boehringer Ingelheim, and Roche Diagnostics; has been a member of a Clinical Endpoints Committee for Bayer; and has been a member of the Trial Steering Committee for Cytokinetics. Dr Lewis has received research funding from the National Institutes of Health (R01-HL 151841, R01-HL131029, and R01-HL159514), American Heart Association (15GPSGC-24800006), Amgen, Cytokinetics, Applied Therapeutics, AstraZeneca, and SoniVie; has received honoraria for advisory boards from Pfizer, Merck, Boehringer Ingelheim, Novartis, American Regent, Cyclerion, Cytokinetics, and Amgen; and has received royalties from UpToDate for scientific content authorship related to exercise physiology. Dr Michels has received consulting/advisor fees from Bristol Myers Squibb, Cytokinetics, and Pfizer; and has received research grant funding from Bristol Myers Squibb. Dr Olivotto has received speakers’ bureau fees from Bristol Myers Squibb, Amicus, and Sanofi Genzyme; has received consulting/advisor fees from Bristol Myers Squibb, Cytokinetics, Sanofi Genzyme, Amicus, Bayer, Tenaya, Rocket Pharma, and Lexeo; and has received research grant funding from Bristol Myers Squibb, Cytokinetics, Sanofi Genzyme, Amicus, Bayer, Menarini International, Chiesi, and Boston Scientific. Dr Oreziak has received investigator fees from Cytokinetics and MyoKardia/Bristol Myers Squibb. Dr Owens has received consulting/advisor fees from Cytokinetics, Bristol Myers Squibb/MyoKardia. Dr Spertus is the principal investigator of grants from the NIH, Abbott Vascular, and the American College of Cardiology Foundation; has received consulting fees from Janssen, Novartis, Amgen, Myokardia, AstraZeneca, Bayer, and Merck; has served on the Scientific Advisory Board of United Healthcare and the Board of Directors for Blue Cross Blue Shield of Kansas City; owns the copyright to the KCCQ, SAQ, and PAQ; and has an equity interest in Health Outcomes Sciences. Dr Solomon has received consulting/advisor fees from Abbott, Action, Akros, Alnylam, Amgen, Arena, AstraZeneca, Bayer, Boehringer Ingelheim, Bristol Myers Squibb, Cardior, Cardurion, Corvia, Cytokinetics, Daiichi-Sankyo, GlaxoSmithKline, Lilly, Merck, MyoKardia, Novartis, Roche, Theracos, Quantum Genomics, Cardurion, Janssen, Cardiac Dimensions, Tenaya, Sanofi-Pasteur, DiNAQOR, Tremeau, CellProThera, Moderna, American Regent, Sarepta, Lexicon, Anacardio, Akros, and Puretech Health; and has received research grants from Actelion, Alnylam, Amgen, AstraZeneca, Bellerophon, Bayer, Bristol Myers Squibb, Celladon, Cytokinetics, Eidos, Gilead, GlaxoSmithKline, Ionis, Lilly, Mesoblast, MyoKardia, NIH/NHLBI, Neurotronik, Novartis, Novo Nordisk, Respicardia, Sanofi Pasteur, Theracos, and US2.AI. Dr Tfelt-Hansen has received consulting fees from Leo Pharma, MicroPort, and Johnson and Johnson. Ms van Sinttruije is a patient advisory committee member and a SEQUOIA-HCM Steering Committee member for Cytokinetics. Dr Watkins has received consulting/advisor fees from Cytokinetics, BioMarin, and BridgeBio. Drs Jacoby, Heitner, Kupfer, Malik, and Meng and Ms Wohltman are employees of Cytokinetics Incorporated and hold stock in Cytokinetics. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)