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Prevalence of Interatrial Block in Healthy School-Aged Children: Definition by P-Wave Duration or Morphological Analysis


Address for correspondence: Polychronis Dilaveris, M.D., F.E.S.C., Department of Cardiology, Hippokration Hospital, 22, Miltiadou Str., 15561, Athens, Greece. Fax: +302-10-748-5039; E-mail:


Background: P waves ≥110 ms in adults and ≥90 ms in children are considered abnormal, signifying interatrial block, particularly in the first case.

Methods: To evaluate the prevalence of interatrial block in healthy school-aged children, we obtained 12-lead digital ECGs (Cardioperfect 1.1, CardioControl NV, Delft, The Netherlands) of 664 healthy children (349 males/315 females, age range 6–14 years old). P-wave analysis indices [mean, maximum and minimum (in the 12 leads) P-wave duration, P-wave dispersion, P-wave morphology in the derived orthogonal (X, Y, Z) leads, as well the amplitude of the maximum spatial P-wave vector] were calculated in all study participants.

Results: P-wave descriptor values were: mean P-wave duration 84.9 ± 9.5 ms, maximum P-wave duration 99.0 ± 9.8 ms, P dispersion 32.2 ± 12.5 ms, spatial P amplitude 182.7 ± 69.0 μV. P-wave morphology distribution in the orthogonal leads were: Type I 478 (72.0%), Type II 178 (26.8%), Type III 1 (0.2%), indeterminate 7 (1%). Maximum P-wave duration was positively correlated to age (P < 0.001) and did not differ between sexes (P = 0.339). Using the 90-ms value as cutoff for P-wave duration, 502 (75.6%) children would be classified as having maximum P-wave duration above reference range. The 95th and the 99th percentiles were in the overall population 117 ms and 125 ms, respectively. P-wave morphology type was not in any way correlated to P-wave duration (P = 0.715).

Conclusions: Abnormal P-wave morphology signifying the presence of interatrial block is very rare in a healthy pediatric population, while widened P waves are quite common, although currently classified as abnormal.

Ann Noninvasive Electrocardiol 2010;15(1):17–25