Atrial flutter with spontaneous 1:1 atrioventricular conduction in adults: an uncommon but frequently missed cause for syncope/presyncope.

Summary AFl with 1:1 AVC is an uncommon but chal-lenging arrhythmia. The best criterion for a cor-rect diagnosis is to be aware of its different pre-sentations and to always consider the diagnosisin patients with history of syncope/presyncope/palpitationswhopresentwithnarroworwideQRStachycardia at rates ≥220 beats/min. References 1. KrappM,KohlT,SimpsonJM,SharlandGK,KatalinicA,GembruchU. Review of diagnosis, treatment, and outcome of fetal atrial ﬂuttercompared with supraventricular tachycardia. Heart 2003, 89:913–917.2. Casey FA, McCrindle BW, Hamilton RM, Gow RM. Neonatal atrialﬂutter: Signiﬁcant early morbidity and excellent long-term progno-sis. Am Heart J 1997; 133:302–306.3. Parmeggiani L, Adamec R, Perrenoud JJ. 1:1 atrial ﬂutter in an el-derly patient: One of the methods of discovering Wolff-Parkinson-White Syndrome. A propos of a case in an adult. Arch Mal CoeurVaiss 1984; 77: 111–117.4. Feld GK, Chen PS, Nicod P, Fleck P, Meyer D. Possible atrial proar-rhythmic affects of class IC antiarrhythmic drugs. Am J Cardiol1990; 66:378–383.5. Brembilla-Perrot B, Houriez P, Beurrier D, Claudon O, Terrier dela Chaise A, Louis P. Predictors of atrial ﬂutter with 1:1 conduc-tion in patients treated with class I antiarrhythmic drugs for atrialtachyarrhythmias. Int J Cardiol 2001; 80:7–15.6. Greenberg HB, Antin SH. 1:1 conduction in atrial ﬂutter afterintravenous injection of aminophylline. J Electrocardiol 1972;5:391–393.7. Finkelstein D, Gold H, Billet S. Atrial ﬂutter with 1:1 AV conduc-tion: Report of six cases. Am J Med 1956; 20:65–76.8. Kennelly BM, Lane G. Electrophysiologic studies in four patientswith atrial ﬂutter with 1:1 atrioventricular conduction. Am Heart J1978; 96:723–730.9. Blanc JJ, Fontalirau F, Gerbaux A, Boschat J, Penther P.Atrial ﬂutter with 1:1 atrioventricular conduction: Electrophys-iologic and histologic correlation. Am Heart J 1984; 109:1045–1049.10. Aranda JM, Moleiro F, Castellanos A, Befeler B. Electrophysiologicstudies in a patient with atrial ﬂutter and 1:1 atrioventricular con-duction. Chest 1975; 68:200–206.11. Pahlajani DB, Miller RA, Serratto M. Patterns of atrioventricularconduction in children. Am Heart J 1975; 90:165–171.12. Chen RH, Chen KP, Wang FZ, Hua W, Chen X, Zhang S. Incidenceand causes of inappropriate detection and therapy by implantabledeﬁbrillators in patients with ventricular tachyarrhythmia. ChinMed J 2006; 119:557–563.13. BatsfordWP,AkhtarM,CaractaAR,JosephsonME,SeidesSF,Dam-ato AN. Effect of atrial stimulation site on the electrophysiologicalproperties of the atrioventricular node in man. Circulation 1974;50:283–292.14. Lister JW, Stein E, Kosowsky BD, Lau SH, Damato AN. Atrioven-tricular conduction in man: Effect of rate, exercise, isoproterenoland atropine on the PR interval. Am J Cardiol 1965; 16:516–523.15. Schoels W, Offner B, Brachmann J, Kuebler W, El-Sherif N. Circusmovement atrial ﬂutter in the sterile pericarditis model. Relationof characteristics of the surface electrogram and conduction prop-erties of the reentrant pathway. J Am Coll Cardiol 1994;23:799–808.