This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/pace.13346. This article is protected by copyright. All rights reserved. Response to adenosine during narrow QRS tachycardia and sinus rhythm: what is the mechanism? Serkan TOPALOGLU, MD a Serhat KOCA, MD a Ozcan OZEKE, MD a Serkan CAY, MD a Firat OZCAN, MD a Dursun ARAS, MD a a Health Science University, Turkiye Yuksek Ihtisas Training and Research Hospital, Department of Electrophysiology, Ankara, Turkey Key Words: Adenosine; supraventricular tachycardia; narrow QRS complex; upper common pathway; atrioventricular reentrant tachycardia, AVNRT Any relationship with industry: No Corresponding to: Ozcan Ozeke, MD Türkiye Yüksek İhtisas Hastanesi Kardiyoloji Klinigi, Ankara, 06100, TURKIYE Tel:+90 505 383 67 73 Fax: +90 312 310 1010 E-mail: ozcanozeke@gmail.com