Left Atrial Size and Function After Spontaneous Cardioversion of Atrial Fibrillation and Their Relation to N-Terminal Atrial Natriuretic Peptide Anna Vittoria Mattioli, MD, Silvia Bonatti, MD, Lorenzo Bonetti, MD, Paola Borella, MD, and Giorgio Mattioli, MD L eft atrial (LA) stunning after cardioversion of atrial fibrillation (AF) has been reported during sponta- neous conversion to sinus rhythm. 1 This observation suggest that atrial stunning is a function of underlying arrhythmia and not of the mode of cardioversion. It is known that AF causes atrial dilation, and progressive LA enlargement occurs when AF becomes chronic. 2 Recently, it has been shown that multiple factors con- tribute to LA enlargement, including the presence and persistence of arrhythmia. 3 Many reports suggest that if sinus rhythm is restored then dilation may regress. 4 The Framingham Study showed a relation between LA size and the risk of stroke in men and the risk of death in both genders. 5–7 Previous studies have sug- gested that N-terminal atrial natriuretic peptide (N- ANP) levels are elevated in patients with AF. 8,9 It is unclear whether AF rather than LA dilation, 10 hemo- dynamic impairment, 11 or another hormonal alter- ation, can result in the elevation of N-ANP levels. 8 The present report evaluates the changes in LA size and function after spontaneous cardioversion of AF and their relation to N-ANP. ••• Hemodynamically stable patients referred for cardio- version for nonrheumatic AF between September 1997 and March 2000 were considered for inclusion in this investigation. The initial study group included 202 con- secutive patients; 98 patients spontaneously recovered sinus rhythm within 48 hours from the onset of arrhyth- mia and were selected for the study (Group A). The study population included 57 men and 41 women of mean age 60  16 years; patients were compared with 98 age- and gender-matched control subjects (mean age 61  16 years) who underwent pharmacologic cardio- version within 48 hours from the onset of arrhythmia (Group B). Patients received intravenous propafenone 2 mg/kg of body weight; the drug was dissolved in 100 ml of 5% glucose and infused over 30 minutes. Exclusion criteria were: atrial flutter, valvular stenosis, valvular prosthesis, significant valvular insufficiency, atrial and/or left ventricular thrombosis, spontaneous echo contrast, patent foramen ovale or an atrial septal aneurysm, or decreased LV function (ejection fraction 45%). No patients received long-term therapy with antiarrhythmic drugs. Demographic and clinical characteristics of the patients are listed in Table 1. Clinical records included age, gender, time and circumstances of the onset of symptoms related to AF, and the duration of AF esti- mated from the initial onset of symptoms until the time of the in-hospital conversion. The protocol was approved by the Ethical Committee of our university and all pa- tients signed an informed consent form. The initial Doppler echocardiographic study was performed during AF and after cardioversion (mean 3  1.5 hours). A complete mono- and 2-dimensional color Doppler echocardiogram was performed in each patient using a commercial Hewlett-Packard echocar- diograph (Andover, Massachusetts) with a 2.5-MHz probe. LA function was assessed using these parameters: (1) transmitral pulsed Doppler recorded from the api- cal 4-chamber view with the sample volume posi- tioned between the tips of the mitral leaflets; peak early filling (E) and atrial filling (A) velocities; and From the Departments of Cardiology and Biomedics, University of Modena and Reggio Emilia, Modena, Italy. Dr. Mattioli’s address is: Department of Cardiology, University of Modena, Via del pozzo, 71, 41100 Modena, Italy. E-mail: mattioli.annavittoria@ unimo.it. Manu- script received December 17, 2002; revised manuscript received and accepted March 3, 2003. TABLE 1 Demographics and Clinical Characteristics Group A (n  98) Group B (n  98) Age (yrs) 60  16 61  16 Men/women 57/41 58/40 Height (cm) 169  13 171  9 Weight (kg) 85  19 87  20 Body mass index (kg/m 2 ) 26  3 25  2 Mean ventricular rate (beats/min) 98  24 97  26 Systemic hypertension 24 (24%) 29 (29%) Diabetes mellitus 9 (9%) 10 (10%) Coronary artery disease 3 (3%) 1 (1%) Mean duration of AF (h) 27  10 29  9 FIGURE 1. LA border traced in the apical 4-chamber view; LA volume calculated using Simpson’s formula. 1478 ©2003 by Excerpta Medica, Inc. All rights reserved. 0002-9149/03/$–see front matter The American Journal of Cardiology Vol. 91 June 15, 2003 doi:10.1016/S0002-9149(03)00404-1