Invited Review ArticleNovel K+ Channel Targets in Atrial Fibrillation Drug Development—Where Are We?El-Haou, Said PhD; Ford, John W. PhD; Milnes, James T. PhDAuthor Information Xention Ltd, Cambridge, United Kingdom. Reprints: John W. Ford, PhD, Xention Ltd, Iconix Park, London Road, Pampisford, Cambridge CB22 3EG, United Kingdom (e-mail: email@example.com). The authors are employees of Xention Ltd and therefore have a financial interest in one or more of the products mentioned within this article. Received January 16, 2015 Accepted April 16, 2015 Journal of Cardiovascular Pharmacology: November 2015 - Volume 66 - Issue 5 - p 412-431 doi: 10.1097/FJC.0000000000000277 Buy Metrics Abstract Abstract: There is a clear unmet medical need for new pharmacologic therapies with improved efficacy and safety for the treatment of atrial fibrillation. Considerable research efforts have been undertaken to discover and develop new safe and effective antiarrhythmic drugs that specifically target atrial K+ channels. To realize the full value of these novel atrial-specific therapeutic drug targets, demonstration of clinical efficacy and safety is required for a new breed of atrial-selective antiarrhythmic drugs. The reward for demonstrating this in a pivotal phase III trial, on regulatory approval, will be “first-in-class” status. This article reviews the development status of new and novel K+ channel inhibitors currently in drug development as atrial-selective antiarrhythmics for the treatment of atrial fibrillation. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.