P Wave Dispersion: A Valuable Non-Invasive Marker of Vulnerability to Atrial Arrhythmias

The prolongation of intraatrial and interatrial conduction time and the non-homogeneous propagation of sinus impulses are well known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation (AF). Previous studies have demonstrated that individuals with clinical history of paroxysmal AF show a significantly increased P wave duration in 12-lead surface electrocardiograms (ECG) and signal-averaged ECG recordings. The inhomogeneous and discontinuous atrial conduction in patients with atrial arrhythmias has been studied, during the last years, with a new ECG index, P wave dispersion. P wave dispersion is defined as the difference between the longest and the shortest P wave duration recorded from multiple different surface ECG leads. Extensive clinical evaluation of P wave dispersion has been performed in the assessment of the risk for AF in patients without apparent heart disease, in hypertensive patients, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. P wave dispersion has proven to be a sensitive and specific ECG predictor of AF in the various clinical settings. However, the methodology used for the calculation of P wave dispersion has not been standardized so far and more efforts to improve the reliability and reproducibility of P wave dispersion measurements are needed. In conclusion, P wave dispersion constitutes a significant contribution to the field of non-invasive electrocardiology and seems to be quite promising in the field of AF prediction. I N T R O D U C T I O N Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. One of the mechanisms implicated in its pathogenesis is the presence of multiple, randomly reentrant wavelets that propagate, become extinct, or fractionate within the atrial tissue. The correlation between the presence of atrial conduction abnormalities and the induction of paroxysmal AF has been well documented [1]. Although markedly prolonged intraand interatrial conduction time can be recognized by prolongation of the surface P wave duration, the question arises as to whether non-homogeneous atrial conduction could be identified by variation in P wave duration between differently oriented surface ECG leads. Regional delays in atrial depolarization might produce a heterogeneous P wave duration because surface P waves in different locations could REvIEw From the 1st University Department of Cardiology, Hippokration Hospital, Athens, Greece HOSPITAL CHRONICLES 2006, 1(3): 130–137 Address for correspondence: Polychronis E. Dilaveris, M.D., 22 Miltiadou Str., GR-15561 Holargos, Athens, Greece Tel/Fax (+301)-6531377 E-mail: [email protected] KEy wORDS: P wave duration, P wave dispersion, atrial fibrillation, atrial