Spatial pattern of P waves in paroxysmal atrial fibrillation patients in sinus rhythm and controls.

BACKGROUND: Measuring body surface potentials in the assessment of the electrical activity of the heart is the most commonly used noninvasive method for diagnosing cardiac arrhythmias. Paroxysmal atrial fibrillation (PAF) patients have disturbed cardiac electrophysiology but the detailed characteristics of atrial activation on the body surface are unknown.
METHODS: P waves from 60 sites on the body surface were analyzed from 10 PAF patients in sinus rhythm (PAF group) and 10 healthy controls (HC group). Evolution of atrial depolarization was described qualitatively by maps of P-wave amplitudes. P-wave dipole evolution was described quantitatively by measuring the changing location (body site) and amplitude of the dipole positive and negative pole peaks.
RESULTS: Both groups exhibited similar dipolar structure with an area of positive and an area of negative potentials. Over the depolarization cycle, there were significant changes in the location of the dipole with the positive pole rotating anteriorly right to left by two electrode sites (10 cm) (P = 0.001). There were significant differences between groups with the positive pole in PAF offset to the right of the chest by 0.43 (0.38) strips compared to HC (P < 0.007). Compared to controls, the PAF group positive poles reached peak amplitude sooner (49 [11] ms vs 65 [14] ms, P = 0.012) and negative poles reached peak amplitude later (74 [13] ms vs 62 [8] ms, P = 0.019).
CONCLUSION: Atrial depolarization is characterized by a single dipole with time-varying amplitude and orientation with significant differences in dipole trajectory between patients with PAF and HCs. ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.