A new terminology for left ventricular walls and location of myocardial infarcts that present Q wave based on the standard of cardiac magnetic resonance imaging: a statement for healthcare professionals from a committee appointed by the International Society for Holter and Noninvasive Electrocardiography.

The ECG is the most frequently used tool for evaluating myocardial infarction (MI). The ECG provides an opportunity to describe location and extent of infarction expressed as pathological Q waves or their equivalents. The terminology used for the left ventricular (LV) walls has varied over time,1–7 although the most currently accepted terms by electrocardiographists have been anterior, septal, lateral, and inferior.8–15 However, terminology has been complicated by use of posterior to refer to either the basal lateral or the basal inferior wall (see below). On the basis of correlations with the postmortem anatomic gold standard reported 50 years ago16 and confirmed later,17,18 the presence of abnormal Q waves in leads V1 and V2 was related to septal wall MI; in V3 and V4 to anterior wall MI; in V5 and V6, I, and aVL to lateral wall MI (I, aVL high lateral; V5 and V6, low lateral); and in II, III, and aVF to inferior wall MI. The presence of abnormally increased R waves in V1 and V2 as a mirror image of Q waves in posterior leads was called a posterior wall infarction. Although similar considerations may be applied for ECG location of ST-segment deviation, this report focuses only on ECG localization of the QRScomplex abnormalities indicative of established MI as depicted by cardiac magnetic resonance (CMR) imaging. Although attempts to standardize the terminology applied to the LV walls have been reported,19,20 differences persist among the terms used by anatomists, pathologists, electrocardiographists, cardiac imagers, and clinicians. However, the pathologist’s view of infarcted myocardium lacks insights into the in vivo positioning of the LV walls. CMR imaging with delayed contrast enhancement (CECMR) has emerged as a new anatomic gold standard technique that provides precise identification of infarcted myocardium in vivo. It is therefore appropriate to use CMR verification of the accuracy of ECG localization on infarction to form the basis for a consensus among healthcare professionals regarding the terminology of the LV walls identified by the Q-wave or Q-wave-equivalent MI patterns on the standard 12-lead ECG. This consensus document is based on the experience of all the members of the committee and a review of the literature about this topic.