Journal of electrocardiology
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Comparative Study
Assessment of ischemic changes by ambulatory ECG-monitoring: comparison with 12-lead ECG during exercise testing.
The accuracy of commercially available ambulatory electrocardiographic monitoring (AEM) systems for reproducing ischemic changes has been questioned. Since these systems are widely used for evaluation of ST-segment changes, both for prognostic purposes and for assessment of the efficacy of antiischemic drugs, such doubts must be clarified. For this purpose, we recorded electrocardiograms (ECGs) during exercise testing, using split leads, simultaneously with a 12-lead electrocardiograph and with the Marquette AEM recorder. ⋯ Of the 19 patients with negative exercise tests only 1 patient had a 1-mm ST-segment depression on AEM. Thus, of the 48 patients studied, similar responses were observed in 47. The results of indicate that the Marquette AEM system is as accurate as the 12-lead ECG in detecting ischemic changes and in assessing their severity.
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Comparative Study
Effect of electrode positioning on ECG interpretation by computer.
The aim of this study was to assess the variability in automated electrocardiogram (ECG) interpretation due to electrode positioning variations. Such variations were simulated by using a set of 746 body surface potential mappings from apparently healthy individuals and patients with myocardial infarction or left ventricular hypertrophy. Four types of electrode position changes were simulated, and the effect on ECG measurements and diagnostic classifications was determined by a computer program. ⋯ In the 40 cases with large diagnostic changes, the cardiologist made no change in 18 cases. The effect of electrode position changes on ECG classification by an expert cardiologist was about half of the effect determined by computerized ECG classification. The effects on classification are significant; therefore, correct placement of chest electrodes remains mandatory.