Redefining the ECG in urban South Africans: Electrocardiographic findings in heart disease-free Africans

Karen Sliwa, Geraldine A. Lee, Melinda J. Carrington, Pro Obel, Andrzej Okreglicki, Simon Stewart

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Abstract

Background: The 12-lead electrocardiogram (ECG) represents an important diagnostic tool for detecting heart disease, but the "normal" ECG in those of African descent has yet to be definitively described. Methods: We systematically analysed 12-lead ECGs from 387 urban South Africans determined to be heart disease free (using the Minnesota code) following advanced cardiologic assessment, including echocardiography, at the Baragwanath Hospital in Soweto, South Africa. Results: 123 males (32%, 41.2 ± 14.5 years) and 264 females (37.4 ± 14.2 years) were studied. Most were in sinus rhythm (87%) and had normal axis (89%). Mean interval data were: PR interval (156 ± 28 ms; 95% CI: 153-159 ms), QRS duration (82 ± 16 ms; 95% CI: 80-84 ms), QT interval (379 ± 48 ms; 95% CI: 374-384 ms) and QTc interval (426 ± 32 ms; 95% CI: 423-429 ms). Overall, 199 (51%; 95% CI: 46.0% to 56.0%) subjects had an ECG "abnormality" or normal variant and 67 ECGs (17%; 95% CI: 13.3% to 20.7%) had major and minor abnormalities. ECG changes normally ascribed to myocardial ischaemia were: i) ST elevation (9.3%; 95% CI: 6.2 to 11.9%), ii) Q waves (7.4%; 95% CI: 4.4 to 9.5%) and iii) ST depression (2.3%; 95% CI: 0.8 to 3.8%). Sokolow-Lyon Index voltage exceeding 38 mm indicative of left ventricular hypertrophy was more prominent in males than females (23.6% vs. 6.4%; OR = 4.5; 95% CI: 2.3-8.5). Conclusions: These data provide a contemporary reference to the 12-lead ECG in urban South Africans found to be heart disease free, with both major and minor abnormalities detected.

Original languageEnglish
Pages (from-to)2204-2209
Number of pages6
JournalInternational Journal of Cardiology
Volume167
Issue number5
DOIs
Publication statusPublished - 1 Sep 2013
Externally publishedYes

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Keywords

  • 12-lead ECG
  • Minnesota coding
  • Urban Africans

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