507 Noninvasive Mapping of Human Atrial Fibrillation MARIA S. GUILLEM, M.S., ∗ ANDREU M. CLIMENT, M.S., ∗ FRANCISCO CASTELLS, Ph.D., ∗ DANIELA HUSSER, M.D.,† JOSE MILLET, Ph.D., ∗ ARASH ARYA, M.D.,† CHRISTOPHER PIORKOWSKI, M.D.,† and ANDREAS BOLLMANN, M.D.† From the ∗ Instituto ITACA, Universidad Polit´ ecnica de Valencia, Valencia, Spain; and †Department of Electrophysiology, Heart Center, Leipzig University, Leipzig, Germany Noninvasive Mapping of Human AF. Introduction: Invasive high-density mapping of atrial fibrilla- tion (AF) has revealed different patterns of atrial activation ranging from single wavefronts to disorganized activation with multiple simultaneous wavefronts. Whether or not similar activation patterns can also be observed using body surface recordings is currently unknown, and was consequently evaluated in this study. Methods and Results: Surface electrocardiographic mapping was performed in 14 patients (age 68 ± 14 years) with persistent AF (AF duration 12 ± 18 months). A total of 56 electrocardiographic leads were placed on the chest over the atria on the front (n = 40) and on the back (n = 16). Using 240-second recordings, wavefront propagation maps were automatically computed and visually classified as either type I (single wavefront), II (single wavefront with wave breakages and splitting), or III (multiple simultaneous wavefronts). Almost half of the patients (n = 6) presented most predominantly type III atrial activation, while six patients mostly presented type I activation. The rest of the patients (n = 2) presented mixed type I and type III activations. This classification showed to be highly reproducible over 4 minutes. Conclusions: Using electrocardiographic body surface mapping during AF, interindividual differences of atrial fibrillatory activation can be observed. The surface activation pattern during AF shows an excellent short-term reproducibility. (J Cardiovasc Electrophysiol, Vol. 20, pp. 507-513, May 2009) atrial fibrillation, atrial wavefronts, body surface potential mapping, electrocardiogram Introduction Atrial fibrillation (AF) is a supraventricular arrhythmia in which the electrical activation shows an uncoordinated pat- tern. The surface electrocardiogram is a valuable tool for its diagnosis. 1-3 In particular, lead V1 is the most com- monly used lead, as fibrillatory waves appear with higher amplitude compared with other leads. 4 However, the 12-lead ECG offers a limited amount of information about the or- ganization degree in the atria in an individual or for further understanding of the mechanisms maintaining AF in each patient. Optical mapping and modeling studies have shown that the electrical activity observed in AF can be maintained by anatomical or functional barriers that may provide a substrate This work was supported by Spanish Ministry of Education and Science under TEC2005-08401 and Universidad Polit´ ecnica de Valencia through its research initiative program. Dr. Husser was supported by the Volkswagen Foundation, Germany and research grants (HU 1679/1-1, DFG and NBL Formel.1-109, Leipzig University). Drs. Guillem and Millet report authorship of a patent on electrode holder system for multielectrode recordings. Address for correspondence: Mar´ ıa de la Salud Guillem S´ anchez, M.S., In- stituto ITACA, Ciudad Polit´ ecnica de la Innovaci´ on, Universidad Polit´ ecnica de Valencia, Camino de Vera s/n, 46022, Valencia, Spain. Fax: (+34) 963877279; E-mail: mguisan@eln.upv.es Manuscript received 12 June 2008; Revised manuscript received 22 Septem- ber 2008; Accepted for publication 22 September 2008. doi: 10.1111/j.1540-8167.2008.01356.x for reentry. 5-7 Observed rotors and spiral waves are thought to be important mechanisms for AF maintenance. 8-14 Different degrees of organization have been observed in epicardial mapping in humans during AF. 15 Previous noninvasive studies have attempted to increase the amount of information recorded in the standard elec- trocardiogram by replacing the electrodes into nonstandard positions. 16,17 Also, the vectorcardiogram (VCG) has been proposed as a tool for the evaluation of atrial wavefronts. 18,19 However, electrical activity during AF is far from being dipo- lar and the use of the VCG for AF characterization should be questioned. Body surface potential mapping (BSPM) has been previously applied to the study of many cardiac dis- eases. 20-25 Despite the advantages of body surface electrical maps over the conventional ECG, they have not been applied so far for the characterization of activation patterns during AF. In this study, we present, for the first time, the potential of body surface maps obtained with a custom-made lead system for the noninvasive evaluation of activation patterns in patients with AF. Methods Patients This study included 14 consecutive patients with persis- tent AF. Their clinical and echocardiographic characteristics are summarized in Table 1. Baseline recordings were acquired in 10 patients for 4 minutes and in four patients for 2 minutes with the pa- tients in a supine position after a 5-minute resting period.