Prevalence and Sex-Specific Distribution of Electrocardiographic Variants in Normotensive Nigerian University Students: A Cross-Sectional Study

Abstract

Background: Electrocardiographic (ECG) variants occurring in the absence of known cardiac disease are common in healthy young adults but remain poorly characterized in sub-Saharan African populations. Contemporary ECG reference standards are predominantly derived from Caucasian cohorts, and their direct application to individuals of African descent risks misclassification of physiologically normal findings as pathological, with consequent unnecessary investigations and healthcare burden. Objective: To determine the prevalence and sex-specific distribution of ECG variants among apparently healthy, normotensive undergraduate students at a Nigerian federal university, and to assess associations between ECG variant status and demographic variables. Methods: A cross-sectional study was conducted among 102 normotensive undergraduate students (55 males, 47 females; mean age 22.4 ± 2.8 years) at the Federal University of Technology, Owerri (FUTO), Imo State, Nigeria. Resting 12-lead ECGs were acquired using standardized protocols and interpreted by a blinded, board-certified cardiologist applying pre-specified diagnostic criteria. Sex-stratified comparisons used chi-square or Fisher's exact tests with Bonferroni correction. Logistic regression assessed independent predictors of key variants. Results: Excluding normal sinus rhythm, at least one ECG variant was identified in 71 participants (69.6%; 95% CI 59.8-78.3%). Juvenile T-wave pattern was the most prevalent variant (37.3%; 95% CI 27.9-47.4%), followed by high QRS voltage (22.5%; 95% CI 14.7-32.0%). Juvenile T-wave pattern was more prevalent in females (48.9% vs 27.3%; p=0.02 uncorrected; OR 0.41, 95% CI 0.19-0.91), while high QRS voltage predominated in males (30.9% vs 12.8%; p=0.02 uncorrected; OR 3.18, 95% CI 1.18-8.55); neither finding survived Bonferroni correction (threshold p<0.006) and both are considered exploratory. Twelve participants (11.8%) exhibited borderline QTc prolongation; structured clinical evaluation confirmed no true pathological QTc prolongation in any participant. Early repolarization was absent in this cohort. Age and BMI were not independently associated with variant prevalence. Conclusion: ECG variants occur in approximately 70% of healthy, normotensive predominantly Igbo university students in south-eastern Nigeria and demonstrate sex-specific patterns. These findings contribute population-specific descriptive data and highlight the need for ethnically informed ECG interpretation to reduce diagnostic misclassification in this population. Multi-center studies across Nigerian and West African cohorts are required to confirm and generalize these observations.