Electrocardiographic Abnormalities in Disease-Free Black South Africans and Correlations With Echocardiographic Indexes and Early Repolarization

Electrocardiographic abnormalities, and specifically early repolarization (ER) patterns, are increasingly found to be common variants in healthy populations free of heart disease or risk factors. Data are sparse in subjects of African descent, for which no increase in adverse cardiovascular outcomes have been demonstrated. A database of healthy disease-free adult volunteers of sub-Saharan African descent had 12 lead electrocardiograms (ECGs) and transthoracic echocardiograms performed. Statistical tests were then performed on the data to elicit associations; 396 volunteers (63.1% women) with a mean age of 37.4 years met the inclusion and exclusion criteria. An abnormal ECG was identified in 50.5% of volunteers, largely because of underlying ST elevation at the J point (ER), left ventricular hypertrophy (LVH) by voltage criteria, and T-wave inversion. Men were more likely to have abnormal ECGs (odds ratio [OR] 1.75; p <0.001), axes (OR 2.05; p = 0.023), display LVH by Sokolow-Lyon voltage criteria (OR 5.45; p <0.001), and have ER patterns (OR 11.61; p <0.001). Additionally, younger adults were also more likely to display LVH by voltage criteria and ER patterns. Volunteers with LVH by ECG had 5.7% higher LV mass indexes (p = 0.047). An abnormal ECG was not associated with a reduced left ventricular ejection fraction or diastolic dysfunction. ECG abnormalities, especially ER patterns, in black adults of Sub-Saharan descent are common, occurring in half of the normal adults.