Time-domain and morphological analysis of the P wave. Part II: effects of atrial pacing on P-wave features.

Background: The aim of this study was to compare time-domain and morphological descriptors of paced and spontaneous P wave in patients prone to atrial fibrillation (AF).

Methods: Nineteen patients (nine women, aged 72 +/- 10 years) affected by paroxysmal AF and implanted with dual-chamber pacemakers (PM) were studied. Two 5-minute recordings were performed during spontaneous and paced rhythm. Electrocardiogram (ECG) signals were acquired using a 32-lead mapping system. Patients were grouped into two classes: no previous AF and previous AF groups, according to the number of AF episodes in the 6 months before the analysis.

Results And Conclusion: During atrial pacing P wave appeared prolonged and morphologically more complex with respect to sinus rhythm. We also found that in patients at lower risk for AF, the atrial pacing changes the atrial activation to a greater extent than in patients at higher risk for AF. Finally, all time-domain and morphological descriptors of the P wave except one succeed in discriminating "no previous AF" and "previous AF" patients in spontaneous rhythm, while no significant differences have been observed during pacing for any parameters.