The American College of Cardiology requests that this document be cited as follows: Maddox TM, Januzzi JL Jr., Allen LA, Breathett K, Butler J, Davis LL, Fonarow GC, Ibrahim NE, Lindenfeld J, Masoudi FA, Motiwala SR, Oliveros E, Patterson JH, Walsh MN, Wasserman A, Yancy CW, Youmans QR. 2021 update to the 2017 ACC expert consensus decision pathway for optimization of heart failure treatment: answers to 10 pivotal issues about heart failure with reduced ejection fraction: a report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol 2021;77:772 810. Copies: This document is available on the website of the American College of Cardiology (http://www.acc.org). For copies of this document, please contact Elsevier Inc. Reprint Department via fax (212 633-3820) or e-mail (reprints@elsevier.com). Permissions: Multiple copies, modi cation, alteration, enhancement, and/or distribution of this document are not permitted without the express permission of the American College of Cardiology. Requests may be completed online via the Elsevier site (https://www.elsevier.com/about/policies/ copyright/permissions). J O U R N A L O F T H E A M E R I C A N C O L L E G E O F C A R D I O L O G Y V O L . 7 7 , N O . 6 , 2 0 2 1 2 0 2 1 B Y T H E A M E R I C A N C O L L E G E O F C A R D I O L O G Y F O U N D A T I O N P U B L I S H E D B Y E L S E V I E R TABLE OF CONTENTS PREFACE 773 ABSTRACT 774 1. INTRODUCTION 774 2. METHODS 775 3. 