Hindawi Publishing Corporation Case Reports in Medicine Volume 2011, Article ID 935951, 2 pages doi:10.1155/2011/935951 Case Report Electrocardiographic Characteristics of Ventricular Arrhythmia Originating from the Left Coronary Cusp Antoine Kossaify,1 Nadir Saoudi,2 and Sami Succar1 1 Electrophysiology Unit, Cardiology Division, CHU-NDS/USEK, Byblos 00003, Lebanon 2 Electrophysiology Unit, Cardiology Division, CH Princess Grace, Monaco 98007, Monaco Correspondence should be addressed to Antoine Kossaify, antoinekossaify@yahoo.com Received 15 June 2011; Accepted 22 September 2011 Academic Editor: Aaron S. Dumont Copyright © 2011 Antoine Kossaify et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Aortic cusps originating arrhythmias are rare; they have special electrocardiogram features that help to locate the site of origin. We report on a 20-year-old male patient without structural heart disease presenting with accelerated idioventricular rhythm; electrocardiogram analysis was typical of left coronary cusp origin. 1. Introduction Outﬂow tract ventricular arrhythmias (VAs) usually have a benign course when occurring in the setting of normal structural heart. Left coronary cusp (LCC) originating arrhythmias have special electrocardiogram (EKG) charac- teristics; these are well established in the literature [1]; recognition of these characteristics is essential for accurate diagnosis and management. 2. Case Presentation We report on a 20-year-old male patient presenting with palpitations; his EKG (Figure S1, which is avialable online at doi: 10.1155/2011/935951) showed accelerated idioventricu- lar rhythm with EKG characteristics compatible with a LCC origin (Figure S2). The patient had no relevant past medical history; physical examination was normal, cardiac echogram showed no structural heart disease, and laboratory param- eters including cardiac markers were normal. Reversion to sinus rhythm occurred with a 75 mg bolus of Xylocaine. Given the refusal of any electrophysiological procedure (diagnostic or therapeutic), the patient was discharged home on day 3 with verapamil. Holter and stress test on days 10 and 30 after discharge showed no VA and were normal. 3. Discussion Supravalvular left ventricular outﬂow tract arrhythmias originate usually from the aortic sinus of valsalva (aortic cusps) [2]. VA originating from the right or left ventricular outﬂow tracts (RVOT and LVOT) can be resembling on surface EKG because these two structures are anatomically adjacent [3]. Both LVOT-VA and RVOT-VA exhibit right axis; RVOT-VA usually displays a typical left bundle branch block pattern without (r) wave in V1 because the activation pattern is typically from the right to the left ventricle [1]. LCC-VA is known to be the most common form of coronary cusp arrhythmia; it exhibits an (r) wave in V1 [1] (so-called atypical left bundle branch block pattern) because the activation vector is directed from posterior to anterior and from the left to the right (LCC is located posteriorly). Right coronary cusp and non-coronary cusp VAs do not exhibit an (r) wave in V1 [1] (these two anatomical structures are located more anteriorly compared to LCC) (Figure S2). LVOT-VA displays earlier precordial transition zones (median V3 versus V5) compared to RVOT-VA [2]; this feature is due to earlier left to right activation pattern in case of LVOT-VA resulting in an earlier (r) wave consequently in precordial leads [3].