P Wave Duration and Dispersion as a Useful Conventional Electrocardiographic Marker for Atrial Fibrillation Prediction

that can be associated with atrial arrhythmias and AF. P-wave dispersion (PWD) is considered a noninvasive electrocardiographic (ECG) marker for atrial remodeling and predictor for AF. 12-15 PWD reflects disturbances of intra-atrial and inter-atrial conduction, and it is defined as the difference between the wider and the narrower P-wave duration recorded from the 12 ECG leads at a paper speed of 50mm/s. The correct measurement of PWD is derived by subtracting the minimum P-wave duration from the maximum in any of the 12 standard surface ECG leads in supine position following 15min of rest and room temperature and lighting kept constant. The onset of the P-wave is defined as the point of first detectable upward or downward slope from the isoelectric line for positive or negative waveforms, respectively. Return to the isoelectric line is considered as the end of the P-wave. PWD can be calculated by manual measurements with hand-held calipers or computerized methods. Manual measurement with hand-held calipers is performed by increasing the ECG rate to 50mm/s and the voltage to 1mV/cm, accompanied by the use of magnification. The normal value of PWD was found to be 29 9ms, and values greater than 40ms indicate the presence of heterogeneous electrical activity in different regions of the atrium that might cause AF to develop. ]