Vectorial theory surpasses the local theory in explaining the origin of P-wave dispersion.

Abstract Background Local theory and the vectorial theory are used to explain the origin of P-wave dispersion (PWD). There are no previous studies that analyze both at the same time. Objectives We set out to determine the implication of local and vectorial theories in the origin of PWD. Methods Cross-sectional study in 153 randomly selected patients aged 18–70 years, undergoing electrophysiological study. Inhomogeneous atrial conduction was evaluated by atrial electrogram dispersion in terms of duration (EGMdurdis) and morphology (EGMmorph dis). P-distal coronary sinus interval (P-DCS) was also measured. P-wave was measured twice, firstly at a calibration of 20 mm/mV and a sweep speed of 50 mm/s, enhancement 10× (basic measurement [BM]), and second time at sweep speed of 150 mm/s, enhancement 80-160× (high precision measurement [HPM]). Results PWD with BM was 48 ms [36–54 ms] while with HPM it was 4 ms [0–10 ms], p Conclusion Vectorial theory explains almost entirely the PWD phenomenon. Inhomogeneous conduction could be an additional mechanism to explain PWD, but its contribution is small.