Determinants of Spatial Dispersion of P-Wave, QRS Complex, and QT-Interval on 12-Lead Electrocardiogram in Apparently Healthy Adults

Abstract

Background: The spatial dispersion of P-wave, QRS complex, and QT interval on 12-lead electrocardiogram are related to the electrical instability in cardiac conducting tissues and elevated parameters are associated with increased risk of cardiovascular morbidity and mortality. Objectives: We sought to evaluate the dispersion of P-wave, QRS complex, and QT interval in healthy adult Nigerians and assess their relationship to age, gender, anthropometric and some physiologic parameters. Methods: A total of 128 subjects were recruited for the study. The participants consist of two groups; a young age group of 62 apparently healthy individuals (aged 18-35 years) and an elderly age group of 66 participants (aged 60-89 years) drawn from attendees to the quarterly medical lectures of the Ebreime Foundation for the Elderly, a non-Governmental organization. The exclusion criteria for the study were presence of acute or chronic illnesses and medications capable of affecting electrocardiogram. All subjects had background medical history assessment, clinical examination and resting 12-lead electrocardiography. The dispersion of P-wave, QRS and QT intervals were measured manually under magnifying glass by one observer and were taken as the difference between the maximum and minimum values of each parameter on standard 12lead electrocardiogram. Results: The elderly subjects had significantly higher body mass index compared to the young subjects. Blood pressure indices were comparable in the two groups. The dispersions of P-wave, QRS and QT on 12-lead electrocardiography were all significantly increased in the elderly. Significant gender variations were noted in QRS dispersion, QTc interval and QT dispersion which were all significantly increased in women. A significant correlation was noted between QT dispersion and body mass index (r = 0.280; p = 0.023). Conclusion: Age, gender and body mass index are significant determinants of P-wave, QRS, and QT dispersion in the adult population. Identification of high risk individuals for cardiovascular disease for prompt preventive intervention is of prime importance.