Sex and Age Differences in Electrocardiographic Parameters Among Adults With Normal
ECGs
at a Single Diagnostic Centre in Owerri, Nigeria: A Retrospective Cross‐Sectional Study
Jovita Eghe Egharevba, Clinton Nwanaga Uche, Chosen Nwaeze Egwim, Acomo Grace, Gerald Olwit, Ivaan Pitua, James Nelson Okema ABSTRACT
Background
Electrocardiographic (ECG) reference values used in Nigerian diagnostic centres are derived from European and North American cohorts, and age‐ and sex‐stratified Nigerian data are scarce.
Methods
In this retrospective cross‐sectional study, 313 12‐lead ECGs reported as normal by a cardiologist at a diagnostic centre in Owerri, Nigeria, were grouped by age (18–40 years, n = 164; ≥ 60 years, n = 149) and sex. Heart rate, P‐wave duration, PR interval, QRS duration and machine‐reported QTc were compared using t ‐tests or Mann–Whitney U tests and two‐way ANOVA, with Bonferroni correction. Sensitivity analyses applied conventional limits uniformly.
Results
Heart rate, P‐wave duration, PR interval and QRS duration did not differ between age groups (all p > 0.09). QTc was longer in older adults (433.7 ± 17.4 vs. 427.4 ± 18.3 ms; p = 0.008), also after heart‐rate adjustment (8.3 ms; 95% CI 4.8 to 11.8). Females had longer QTc than males in both age groups (by 14.6 and 11.6 ms; both p < 0.001) in all analyses. Males had wider QRS than females only in younger adults (95.7 vs. 89.5 ms; p < 0.001), but this age‐by‐sex interaction ( p = 0.007) was not significant when limits were applied uniformly ( p = 0.076). PR stopped at 200 ms in both age groups, consistent with selection.
Conclusion
The female‐longer QTc was the most consistent finding, and older adults had modestly longer QTc. Age‐related conduction differences may have been masked by selection; unselected multicentre data are needed before reference intervals are adopted.