P-Wave Dispersion and Atrial Fibrillation Risk: Methodological Considerations

READERS’ COMMENTS P-Wave Dispersion and Atrial Fibrillation Risk: Methodological Considerations We read with great interest the report of Magnani et al1 on P-wave duration and risk for longitudinal atrial fibrillation (AF) in patients aged ⱖ60 years from the Framingham Heart Study. Using a single-channel electrocardiographic (ECG) recording, the investigators found that maximum P-wave duration at the upper fifth percentile was associated with long-term AF risk in an elderly community-based cohort. Moreover, they found no significant associations between P-wave dispersion and the incidence of AF or mortality. Although the results are interesting, we believe that they should be considered cautiously because of the lack of simultaneous recording of all 12 ECG leads. Simultaneous recording of ECG leads has been considered a prerequisite to calculate any “P-wave dispersion index” since the early report of Buxton and Josephson.2 They introduced the isoelectric interval, which was derived by subtracting the longest P-wave duration in the standard limb lead from the total P-wave duration, measured from the earliest onset to the latest end of the P wave in any of the simultaneously recorded leads I, II, and III.2 Our research group has introduced P-wave dispersion as a simple ECG predictor of paroxysmal lone AF.3 Although acceptable intraobserver and interobserver error in the measurement of P-wave duration on 12-lead electrocardiography

have been reported,3 well-known difficulties in defining P-wave onset and offset may restrict the accuracy and reproducibility of the measurements. To overcome some of these restrictions, averaging techniques used in advanced recording devices and magnified graticules on standard computer screens have proved useful in the accurate evaluation of common P-wave descriptors.4 In any case, simultaneous recording of all 12 ECG leads is mandatory to reduce the time-related well-known lability of P-wave features. The lability of P-wave characteristics in normal subjects has been reported previously.5 Changes in P-wave amplitude during physical daily activities, such as positional changes, respiration, and exercise, have already been demonstrated.6 Finally, the circadian behavior of P-wave characteristics may also induce possible imprecision in measurements when a single-channel ECG recording is used.7 To achieve greater precision in measuring P-wave dispersion, we believe that simultaneous recording of all 12 ECG leads is mandatory to examine AF risk, particularly when a single ECG is recorded in each patient. Polychronis Dilaveris, MD Christodoulos Stefanadis, MD Athens, Greece 29 January 2011

1. Magnani JW, Johnson VM, Sullivan LM, Gorodeski EZ, Schnabel RB, Lubitz SA, Levy D, Ellinor PT, Benjamin EJ. P wave duration and risk of longitudinal atrial fibrillation risk in persons ⱖ60 years old (from

Am J Cardiol 2011;107:1405–1407 0002-9149/11/$ – see front matter © 2011 Elsevier Inc. All rights reserved.

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the Framingham Heart Study). Am J Cardiol In press. Buxton AE, Josephson ME. The role of P wave duration as a predictor of postoperative atrial arrhythmias. Chest 1981;80:68 –73. Dilaveris PE, Gialafos EJ, Sideris SK, Theopistou AM, Andrikopoulos GK, Kyriakidis M, Gialafos JE, Toutouzas PK. Simple electrocardiographic markers for the prediction of paroxysmal idiopathic atrial fibrillation. Am Heart J 1998;135:733–738. Dilaveris P, Batchvarov V, Gialafos J, Malik M. Comparison of different methods for manual P wave duration measurement in 12-lead electrocardiograms. Pacing Clin Electrophysiol 1999;22:1532–1538. Forfang K, Erikseen J. Significance of P wave terminal force in presumably healthy men. Am Heart J 1978;96:739 –743. Shandling AH, Florio J, Castellanet MJ, Messenger JC, Crump R, Evans K, Rylaarsdarm A, Nolasco M. Physical determinants of the endocardial P wave. Pacing Clin Electrophysiol 1990;13:1585–1589. Dilaveris PE, Färbom P, Batchvarov V, Ghuran A, Malik M. Circadian behavior of P-wave duration, P-wave area, and PR interval in healthy subjects. Ann Noninvas Electrocardiol 2001;6:92–97. doi:10.1016/j.amjcard.2011.02.001

Erratum for Tatsumi et al. “Utility of Comprehensive Assessment of Strain Dyssynchrony Index by Speckle Tracking Imaging for Predicting Response to Cardiac Resynchronization Therapy” Am J Cardiol 2011;107:439 – 446. The images for Figures 1, 2, and 4 were not correctly depicted. The correct images are shown on the following 2 pages. doi:10.1016/j.amjcard.2011.01.036

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