P Wave Analysis in the Era of Atrial Fibrillation Ablation Fabio M. Leonelli, MD a , Emanuela T. Locati, MD, PhD b , Giuseppe Bagliani, MD c,d, *, Roberto De Ponti, MD, FHRS e , Luigi Padeletti, MD f , Laura Cipolletta, MD g , Alessandro Capucci, MD g INTRODUCTION Atrial fibrillation (AF), affecting 1% to 2% of general population, is the most common sustained arrhythmia. It is also related to increased hospital- izations and mortality, causing a significant in- crease in health care financial resources spent for AF treatment. Its prevalence and incidence of associated morbidity dramatically increases with age. 1 The usual role of the electrocardiogram (ECG) in the management of AF is to diagnose this arrhythmia, to monitor the effects of antiar- rhythmic drugs (AADs), and to assess the ventric- ular response during episodes of AF. In a patient complaining of palpitations, AF episodes can be suspected by simple pulse palpation by the patient or relatives, or by documenting heart rate by using modern sphygmomanometers that are able to identify irregular cardiac rhythms. The suspicion of AF can then be confirmed by a 12-lead ECG, which can differentiate between AF and other irregular rhythms. More recently, single-lead tracings can be ob- tained using small tools attached to a smartphone, allowing low-cost continuous monitoring of pa- tients with arrhythmias. Despite its obvious limitations, surface ECG and its applications remains a very valuable tool, not only in the diagnosis of AF but also in the definition of its proarrhythmic substrate and response to therapy. a Cardiology Department, James A. Haley Veterans’ Hospital, Cardiology Department University South Florida, Tampa, FL, USA; b Electrophysiology Unit, Cardiovascular Department, Niguarda Hospital, Milan, Italy; c Cardiology Department, Arrhythmology Unit, Foligno General Hospital, Foligno, Italy; d Cardiovascular Dis- eases Department, University of Perugia, Perugia, Italy; e Cardiology Department, University of Insubria, Var- ese, Italy; f Heart and Vessels Department, University of Florence, IRCCS Multimedica, Sesto San Giovanni, Florence, Italy; g Cardiology and Arrhythmology Clinic, Marche Polytechnic University, University Hospital “Ospedali Riuniti”, Ancona, Italy * Corresponding author. Cardiology Department, Arrhythmology Unit, Foligno General Hospital, Foligno, Italy. E-mail address: Giuseppe.bagliani@tim.it KEYWORDS  Atrial fibrillation  Atrial remodeling  Holter recording  P wave KEY POINTS  Atrial fibrillation (AF) is a complex arrhythmia not yet completely understood.  The role of surface electrocardiogram (ECG) is only apparently limited by the disorganized nature of AF.  Attentive analysis of the ECG can greatly help in the diagnosis and management of AF.  Electrocardiographic techniques useful in characterizing and managing AF include Holter moni- toring and frequency domain analysis of atrial electrograms. Card Electrophysiol Clin 10 (2018) 299–316 https://doi.org/10.1016/j.ccep.2018.02.015 1877-9182/18/Ó 2018 Elsevier Inc. All rights reserved. cardiacEP.theclinics.com