Objectives: To determine the value of routine versus selective use of the 18-lead electrocardiogram in determining the size of an acute inferior myocardial infarction (MI). Design: Prospective, quasi-experimental, random assignment. Setting: The coronary care unit (CCU) of a major teaching hospital in South Australia. Patients: Fifty-two patients admitted to the CCU with acute evolving interior MI. Outcome Measures: Correlation and comparison of the predictions of right ventricular (RV) and posterior wall (PW) lead ST elevation with prospectively chosen markers on the 12-lead electrocardiogram-ST elevation in lead III > II and precordial ST depression, and the predictions by coronary care nurses. Procedure: The results of 18-lead electrocardiograms of 52 consecutive patients admitted to the CCU with acute evolving inferior MI were classified according to prospectively chosen criteria. Coronary care nurses were randomly assigned four 12-lead electrocardiograms and asked to 'blindly' predict ST elevation in the concurrent RV and PW leads. Results: ST elevation in lead III > II demonstrated a sensitivity and positive predictive accuracy ot 86% to 1 mm of ST elevation in the RV leads. ST depression in V1, V2, and V3 similarly demonstrated a 75% sensitivity and 89% positive predictive accuracy to 1 mm of ST elevation in the PW leads. In comparison, coronary care nurses proved to be as accurate in their predictions of additional PW ST elevation (p = 0.73), but were significantly less able to predict RV ST elevation (p = 0.049). These predictions were independent of the level of experience and qualifications. Conclusions: Discriminating between smaller and larger types of inferior MIs has the potential to alter patient management: Thirty-two percent of patients in the study demonstrated additional ST elevation in both the RV and PW leads. Both of the 12-lead electrocardiogram markers used in this study proved reasonably accurate in predicting additional ST elevation in the leads that normally comprise the 18-lead electrocardiogram. Recognition of these markers has the potential to expedite the need for the additional 18-lead electrocardiogram when rapid assessment of infarction size is required. However, the routine use of the 18-lead electrocardiogram is supported by this study.
|Number of pages||10|
|Journal||Heart and Lung: Journal of Acute and Critical Care|
|Publication status||Published - 1 Jan 1996|