The Diagnostic Yield of Routine Electrocardiography in Hypertension and Implications for Care in a Southwestern Nigerian Practice

Abstract

Background: Nigeria, like other developing nations, has an increasing burden of hypertension. Electrocardiography is an integral part of the diagnostic work-up for the newly diagnosed hypertensive subjects. The aim of this study was to determine the diagnostic yield of electrocardiography in hypertensive patients of a southwestern Nigerian hospital. Patients and Methods: This was a retrospective descriptive study of electrocardiographs of hypertensive patients over a six-year period. Electrographic variables of interest were cardiac rhythm and rate, left ventricular hypertrophy (LVH), left atrial enlargement (LAE), T wave abnormalities, cardiac axis, blocks, complexes, QT segment abnormalities, atrial fibrillation (AF)/flutter, supraventricular tachycardia and pre-excitation syndrome. The Pearson's chi square was used to test for differences across age groups (15-44yrs, 45-64yrs and >65yrs) and between male and female subjects with the significance level set at 5% (p< 0.05). Results: Hypertension was the indication for 40% of electrocardiographs completed and comprised of 3713 electrocardiograms (ECG) over a six-year period. The commonest abnormalities were left axis deviation (LAD) (32.2%), LVH (20.7%), rhythm abnormalities (16.7%) and LAE (14.5%). The diagnostic yield (presence of at least one electrographic abnormality) was 51% in 15-44 yrs age group, 64% in middle aged and 76.5% in the >65 yrs age group. While the male subjects in this study had a slightly increased likelihood of having an abnormal finding (odds ratio 1.18: 95% CI 1.02-1.35), the odds ratio for an abnormal ECG in subjects younger than 45 years was 0.48 (95% CI 0.41-0.57). Conclusion:The diagnostic yield of electrocardiography in this study was considerable, although lowest in subjects younger than 45 years and increased with age. This may reflect an increased burden and earlier onset of hypertension and its complications. This should also engender prompt and aggressive management of hypertension, especially in the elderly in whom the cardiovascular complications from hypertension is most severe.