P-wave dynamics of the electrocardiogram during the annual cycle in Northern European women

Dynamic alterations in the bioelectrical activity of the atrial myocardium exhibit annual variation, a phenomenon that remains largely unexplored in women. This study aimed to investigate the influence of climate on the annual and seasonal dynamics of P-wave amplitude and duration, P-Q duration, and heart rate (HR). The study cohort comprised 313 apparently healthy women (age 40.9 ± 2.1 y) residing in the European North (62° N, 51° E). Electrocardiograms were recorded monthly using the standard 12-lead configuration. Annual drift in P-wave amplitude was observed in leads I - and V4-6 (p < 0.05-0.001). The P-wave amplitude was significantly greater in winter (December‒February) than in autumn (September‒November): 0.076 ± 0.037 mV and 0.061 ± 0.023 mV, respectively, representing a 56.5% increase (p < 0.001). Grouped by season the amplitudes of the P wave were the lowest in autumn (0.061 + 0.023 mV), then increased in winter (0.076 + 0.037 Mv) by 24.6% (p < 0.001). P-Q segment duration, P-Q interval duration, P-wave duration, and HR did not differ seasonally (p > 0.05). During the winter, the P-wave amplitude correlated with the ambient temperature (-0.254, p < 0.05), whereas in autumn, it correlated with the relative humidity (-0.213, p < 0.05). These findings suggest that variability in P-wave amplitude in healthy women is associated with adaptive responses to meteorological variations throughout the year.