Prediction of right ventricular and posterior wall ST elevation by coronary care nurses: The 12-lead electrocardiograph versus the 18-lead electrocardiograph

Abstract

Objective 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 inferior 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 of 86% to 1 mm of ST elevation in the RV leads. ST depression in V 1, V 2, and V 3 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.